atomic nitrogen doping: Topics by WorldWideScience.org

Sample records for atomic nitrogen doping

Electronic structure of graphene nanoribbons doped with nitrogen atoms: a theoretical insight.

Science.gov (United States)

Torres, A E; Fomine, S

2015-04-28

The electronic structure of graphene nanoribbons doped with a graphitic type of nitrogen atoms has been studied using B3LYP, B2PLYP and CAS methods. In all but one case the restricted B3LYP solutions were unstable and the CAS calculations provided evidence for the multiconfigurational nature of the ground state with contributions from two dominant configurations. The relative stability of the doped nanoribbons depends mostly on the mutual position of the dopant atoms and notably less on the position of nitrogen atoms within the nanoribbon. N-graphitic doping affects cationic states much more than anionic ones due the participation of the nitrogen atoms in the stabilization of the positive charge, resulting in a drop in ionization energies (IPs) for N-graphitic doped systems. Nitrogen atoms do not participate in the negative charge stabilization of anionic species and, therefore, the doping does not affect the electron affinities (EAs). The unrestricted B3LYP method is the method of choice for the calculation of IPs and EAs. Restricted B3LYP and B2PLYP produces unreliable results for both IPs and EAs while CAS strongly underestimates the electron affinities. This is also true for the reorganization energies where restricted B3LYP produces qualitatively incorrect results. Doping changes the reorganization energy of the nanoribbons; the hole reorganization energy is generally higher than the corresponding electron reorganization energy due to the participation of nitrogen atoms in the stabilization of the positive charge.
Direct visualization of atomically precise nitrogen-doped graphene nanoribbons

International Nuclear Information System (INIS)

Zhang, Yi; Zhang, Yanfang; Li, Geng; Lu, Jianchen; Du, Shixuan; Gao, Hong-Jun; Lin, Xiao; Berger, Reinhard; Feng, Xinliang; Müllen, Klaus

2014-01-01

We have fabricated atomically precise nitrogen-doped chevron-type graphene nanoribbons by using the on-surface synthesis technique combined with the nitrogen substitution of the precursors. Scanning tunneling microscopy and spectroscopy indicate that the well-defined nanoribbons tend to align with the neighbors side-by-side with a band gap of 1.02 eV, which is in good agreement with the density functional theory calculation result. The influence of the high precursor coverage on the quality of the nanoribbons is also studied. We find that graphene nanoribbons with sufficient aspect ratios can only be fabricated at sub-monolayer precursor coverage. This work provides a way to construct atomically precise nitrogen-doped graphene nanoribbons.
The atomic and electronic structure of nitrogen- and boron-doped phosphorene.

Science.gov (United States)

Boukhvalov, Danil W

2015-10-28

First principles modeling of nitrogen- and boron-doped phosphorene demonstrates the tendency toward the formation of highly ordered structures. Nitrogen doping leads to the formation of -N-P-P-P-N- lines. Further transformation into -P-N-P-N- lines across the chains of phosphorene occurs with increasing band gap and increasing nitrogen concentration, which coincides with the decreasing chemical activity of N-doped phosphorene. In contrast to the case of nitrogen, boron atoms prefer to form -B-B- pairs with the further formation of -P-P-B-B-P-P- patterns along the phosphorene chains. The low concentration of boron dopants converts the phosphorene from a semiconductor into a semimetal with the simultaneous enhancement of its chemical activity. Co-doping of phosphorene by both boron and nitrogen starts from the formation of -B-N- pairs, which provides flat bands and further transformation of these pairs into hexagonal BN lines and ribbons across the phosphorene chains.
Ultraviolet electroluminescence from nitrogen-doped ZnO-based heterojuntion light-emitting diodes prepared by remote plasma in situ atomic layer-doping technique.

Science.gov (United States)

Chien, Jui-Fen; Liao, Hua-Yang; Yu, Sheng-Fu; Lin, Ray-Ming; Shiojiri, Makoto; Shyue, Jing-Jong; Chen, Miin-Jang

2013-01-23

Remote plasma in situ atomic layer doping technique was applied to prepare an n-type nitrogen-doped ZnO (n-ZnO:N) layer upon p-type magnesium-doped GaN (p-GaN:Mg) to fabricate the n-ZnO:N/p-GaN:Mg heterojuntion light-emitting diodes. The room-temperature electroluminescence exhibits a dominant ultraviolet peak at λ ≈ 370 nm from ZnO band-edge emission and suppressed luminescence from GaN, as a result of the decrease in electron concentration in ZnO and reduced electron injection from n-ZnO:N to p-GaN:Mg because of the nitrogen incorporation. The result indicates that the in situ atomic layer doping technique is an effective approach to tailoring the electrical properties of materials in device applications.
Control of work function of graphene by plasma assisted nitrogen doping

International Nuclear Information System (INIS)

Akada, Keishi; Terasawa, Tomo-o; Imamura, Gaku; Obata, Seiji; Saiki, Koichiro

2014-01-01

Nitrogen doping is expected to provide several intriguing properties to graphene. Nitrogen plasma treatment to defect-free and defective highly oriented pyrolytic graphite (HOPG) samples causes doping of nitrogen atom into the graphene layer. Nitrogen atoms are initially doped at a graphitic site (inside the graphene) for the defect-free HOPG, while doping to a pyridinic or a pyrrolic site (edge of the graphene) is dominant for the defective HOPG. The work function of graphene correlates strongly with the site and amount of doped nitrogen. Nitrogen atoms doped at a graphitic site lower the work function, while nitrogen atoms at a pyridinic or a pyrrolic site increase the work function. Control of plasma treatment time and the amount of initial defect could change the work function of graphite from 4.3 eV to 5.4 eV, which would open a way to tailor the nature of graphene for various industrial applications
Sub-ambient carbon dioxide adsorption properties of nitrogen doped graphene

Energy Technology Data Exchange (ETDEWEB)

Tamilarasan, P.; Ramaprabhu, Sundara, E-mail: ramp@iitm.ac.in [Alternative Energy and Nanotechnology Laboratory (AENL), Nano Functional Materials Technology Centre (NFMTC), Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)

2015-04-14

Carbon dioxide adsorption on carbon surface can be enhanced by doping the surface with heterogeneous atoms, which can increase local surface affinity. This study presents the carbon dioxide adsorption properties of nitrogen doped graphene at low pressures (<100 kPa). Graphene was exposed to nitrogen plasma, which dopes nitrogen atoms into carbon hexagonal lattice, mainly in pyridinic and pyrrolic forms. It is found that nitrogen doping significantly improves the CO{sub 2} adsorption capacity at all temperatures, due to the enrichment of local Lewis basic sites. In general, isotherm and thermodynamic parameters suggest that doped nitrogen sites have nearly same adsorption energy of surface defects and residual functional groups. The isosteric heat of adsorption remains in physisorption range, which falls with surface coverage, suggesting the distribution of magnitude of adsorption energy. The absolute values of isosteric heat and entropy of adsorption are slightly increased upon nitrogen doping.
Nitrogen-doped porous carbon from Camellia oleifera shells with enhanced electrochemical performance

International Nuclear Information System (INIS)

Zhai, Yunbo; Xu, Bibo; Zhu, Yun; Qing, Renpeng; Peng, Chuan; Wang, Tengfei; Li, Caiting; Zeng, Guangming

2016-01-01

Nitrogen doped porous activated carbon was prepared by annealing treatment of Camellia oleifera shell activated carbon under NH 3 . We found that nitrogen content of activated carbon up to 10.43 at.% when annealed in NH 3 at 800 °C. At 600 °C or above, the N-doped carbon further reacts with NH 3 , leads to a low surface area down to 458 m 2 /g and low graphitization degree. X-ray photoelectron spectroscope (XPS) analysis indicated that the nitrogen functional groups on the nitrogen-doped activated carbons (NACs) were mostly in the form of pyridinic nitrogen. We discovered that the oxygen groups and carbon atoms at the defect and edge sites of graphene play an important role in the reaction, leading to nitrogen atoms incorporated into the lattice of carbon. When temperatures were lower than 600 °C the nitrogen atoms displaced oxygen groups and formed nitrogen function groups, and when temperatures were higher than 600 °C and ~ 4 at.% carbon atoms and part of oxygen function groups reacted with NH 3 . When compared to pure activated carbon, the nitrogen doped activated carbon shows nearly four times the capacitance (191 vs 51 F/g). - Highlights: • The nitrogen content up to 10.43 at % during CAC pyrolysis under NH3 at 800 °C. • The oxygen groups and carbon atoms played an important role in the nitrogen doping. • NAC-600 shows a much higher specific capacitance than CAC.
Nitrogen doping in atomic layer deposition grown titanium dioxide films by using ammonium hydroxide

Energy Technology Data Exchange (ETDEWEB)

Kaeaeriaeinen, M.-L., E-mail: marja-leena.kaariainen@lut.fi; Cameron, D.C.

2012-12-30

Titanium dioxide films have been created by atomic layer deposition using titanium chloride as the metal source and a solution of ammonium hydroxide in water as oxidant. Ammonium hydroxide has been used as a source of nitrogen for doping and three thickness series have been deposited at 350 Degree-Sign C. A 15 nm anatase dominated film was found to possess the highest photocatalytic activity in all film series. Furthermore almost three times better photocatalytic activity was discovered in the doped series compared to undoped films. The doped films also had lower resistivity. The results from X-ray photoemission spectroscopy showed evidence for interstitial nitrogen in the titanium dioxide structure. Besides, there was a minor red shift observable in the thickest samples. In addition the film conductivity was discovered to increase with the feeding pressure of ammonium hydroxide in the oxidant precursor. This may indicate that nitrogen doping has caused the decrease in the resistivity and therefore has an impact as an enhanced photocatalytic activity. The hot probe test showed that all the anatase or anatase dominant films were p-type and all the rutile dominant films were n-type. The best photocatalytic activity was shown by anatase-dominant films containing a small amount of rutile. It may be that p-n-junctions are formed between p-type anatase and n-type rutile which cause carrier separation and slow down the recombination rate. The combination of nitrogen doping and p-n junction formation results in superior photocatalytic performance. - Highlights: Black-Right-Pointing-Pointer We found all N-doped and undoped anatase dominating films p-type. Black-Right-Pointing-Pointer We found all N-doped and undoped rutile dominating films n-type. Black-Right-Pointing-Pointer We propose that p-n junctions are formed in anatase-rutile mixture films. Black-Right-Pointing-Pointer We found that low level N-doping has increased TiO{sub 2} conductivity. Black
Nitrogen-doped graphene by microwave plasma chemical vapor deposition

International Nuclear Information System (INIS)

Kumar, A.; Voevodin, A.A.; Paul, R.; Altfeder, I.; Zemlyanov, D.; Zakharov, D.N.; Fisher, T.S.

2013-01-01

Rapid synthesis of nitrogen-doped, few-layer graphene films on Cu foil is achieved by microwave plasma chemical vapor deposition. The films are doped during synthesis by introduction of nitrogen gas in the reactor. Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy and scanning tunneling microscopy reveal crystal structure and chemical characteristics. Nitrogen concentrations up to 2 at.% are observed, and the limit is linked to the rigidity of graphene films on copper surfaces that impedes further nitrogen substitutions of carbon atoms. The entire growth process requires only a few minutes without supplemental substrate heating and offers a promising path toward large-scale synthesis of nitrogen-doped graphene films. - Highlights: ► Rapid synthesis of nitrogen doped few layer graphene on Cu foil. ► Defect density increment on 2% nitrogen doping. ► Nitrogen doped graphene is a good protection to the copper metallic surface
Nitrogen-doped graphene by microwave plasma chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Kumar, A., E-mail: kumar50@purdue.edu [Birck Nanotechnolgy Center, Purdue University, West Lafayette, IN 47907 (United States); Voevodin, A.A. [Birck Nanotechnolgy Center, Purdue University, West Lafayette, IN 47907 (United States); Materials and Manufacturing Directorate, Air Force Research Laboratory, WPAFB, OH 45433 (United States); Paul, R. [Birck Nanotechnolgy Center, Purdue University, West Lafayette, IN 47907 (United States); Altfeder, I. [Materials and Manufacturing Directorate, Air Force Research Laboratory, WPAFB, OH 45433 (United States); Zemlyanov, D.; Zakharov, D.N. [Birck Nanotechnolgy Center, Purdue University, West Lafayette, IN 47907 (United States); Fisher, T.S., E-mail: tsfisher@purdue.edu [Birck Nanotechnolgy Center, Purdue University, West Lafayette, IN 47907 (United States); Materials and Manufacturing Directorate, Air Force Research Laboratory, WPAFB, OH 45433 (United States)

2013-01-01

Rapid synthesis of nitrogen-doped, few-layer graphene films on Cu foil is achieved by microwave plasma chemical vapor deposition. The films are doped during synthesis by introduction of nitrogen gas in the reactor. Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy and scanning tunneling microscopy reveal crystal structure and chemical characteristics. Nitrogen concentrations up to 2 at.% are observed, and the limit is linked to the rigidity of graphene films on copper surfaces that impedes further nitrogen substitutions of carbon atoms. The entire growth process requires only a few minutes without supplemental substrate heating and offers a promising path toward large-scale synthesis of nitrogen-doped graphene films. - Highlights: ► Rapid synthesis of nitrogen doped few layer graphene on Cu foil. ► Defect density increment on 2% nitrogen doping. ► Nitrogen doped graphene is a good protection to the copper metallic surface.
Nitrogen-doped porous carbon from Camellia oleifera shells with enhanced electrochemical performance

Energy Technology Data Exchange (ETDEWEB)

Zhai, Yunbo, E-mail: ybzhai@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Xu, Bibo [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Zhu, Yun [Office of Scientific R& D, Hunan University, Changsha 410082 (China); Qing, Renpeng; Peng, Chuan; Wang, Tengfei; Li, Caiting; Zeng, Guangming [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China)

2016-04-01

Nitrogen doped porous activated carbon was prepared by annealing treatment of Camellia oleifera shell activated carbon under NH{sub 3}. We found that nitrogen content of activated carbon up to 10.43 at.% when annealed in NH{sub 3} at 800 °C. At 600 °C or above, the N-doped carbon further reacts with NH{sub 3}, leads to a low surface area down to 458 m{sup 2}/g and low graphitization degree. X-ray photoelectron spectroscope (XPS) analysis indicated that the nitrogen functional groups on the nitrogen-doped activated carbons (NACs) were mostly in the form of pyridinic nitrogen. We discovered that the oxygen groups and carbon atoms at the defect and edge sites of graphene play an important role in the reaction, leading to nitrogen atoms incorporated into the lattice of carbon. When temperatures were lower than 600 °C the nitrogen atoms displaced oxygen groups and formed nitrogen function groups, and when temperatures were higher than 600 °C and ~ 4 at.% carbon atoms and part of oxygen function groups reacted with NH{sub 3}. When compared to pure activated carbon, the nitrogen doped activated carbon shows nearly four times the capacitance (191 vs 51 F/g). - Highlights: • The nitrogen content up to 10.43 at % during CAC pyrolysis under NH3 at 800 °C. • The oxygen groups and carbon atoms played an important role in the nitrogen doping. • NAC-600 shows a much higher specific capacitance than CAC.
Nitrogen-doped carbon monolith for alkaline supercapacitors and understanding nitrogen-induced redox transitions.

Science.gov (United States)

Wang, Da-Wei; Li, Feng; Yin, Li-Chang; Lu, Xu; Chen, Zhi-Gang; Gentle, Ian R; Lu, Gao Qing; Cheng, Hui-Ming

2012-04-23

A nitrogen-doped porous carbon monolith was synthesized as a pseudo-capacitive electrode for use in alkaline supercapacitors. Ammonia-assisted carbonization was used to dope the surface with nitrogen heteroatoms in a way that replaced carbon atoms but kept the oxygen content constant. Ammonia treatment expanded the micropore size-distributions and increased the specific surface area from 383 m(2) g(-1) to 679 m(2) g(-1). The nitrogen-containing porous carbon material showed a higher capacitance (246 F g(-1)) in comparison with the nitrogen-free one (186 F g(-1)). Ex situ electrochemical spectroscopy was used to investigate the evolution of the nitrogen-containing functional groups on the surface of the N-doped carbon electrodes in a three-electrode cell. In addition, first-principles calculations were explored regarding the electronic structures of different nitrogen groups to determine their relative redox potentials. We proposed possible redox reaction pathways based on the calculated redox affinity of different groups and surface analysis, which involved the reversible attachment/detachment of hydroxy groups between pyridone and pyridine. The oxidation of nitrogen atoms in pyridine was also suggested as a possible reaction pathway. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Tailoring thermal transport properties of graphene by nitrogen doping

Energy Technology Data Exchange (ETDEWEB)

Zhang, Tingting; Li, Jianhua; Cao, Yuwei; Zhu, Liyan, E-mail: lyzhu@hytc.edu.cn; Chen, Guibin, E-mail: gbchen@hytc.edu.cn [Huaiyin Normal University, School of Physics and Electronic & Electrical Engineering (China)

2017-02-15

The influence of two different nitrogen doping configurations, graphite-like and pyridinic-like nitrogen doping (denoted as graphite-N and pyridinic-N hereafter, respectively), on the thermal conduction of graphene is carefully studied via non-equilibrium molecular dynamic (NEMD) simulations. The thermal conductivity is more strongly suppressed in the pyridinic-N-doped graphene than that in the graphite-N-doped sample, which can be well understood from the changes in bond strength between nitrogen and carbon atoms, phonon group velocities, phonon density of states, participation ratio, and phonon transmission. Our study indicates that the pyridinic-N doping is an efficient method to tune the thermal conduction in graphene, especially for the situation where low thermal conductivity is requested, e.g., thermoelectric applications and thermal shielding.
Growth of nitrogen-doped graphene on copper: Multiscale simulations

Science.gov (United States)

Gaillard, P.; Schoenhalz, A. L.; Moskovkin, P.; Lucas, S.; Henrard, L.

2016-02-01

We used multiscale simulations to model the growth of nitrogen-doped graphene on a copper substrate by chemical vapour deposition (CVD). Our simulations are based on ab-initio calculations of energy barriers for surface diffusion, which are complemented by larger scale Kinetic Monte Carlo (KMC) simulations. Our results indicate that the shape of grown doped graphene flakes depends on the temperature and deposition flux they are submitted during the process, but we found no significant effect of nitrogen doping on this shape. However, we show that nitrogen atoms have a preference for pyridine-like sites compared to graphite-like sites, as observed experimentally.
Structures of Pt clusters on graphene doped with nitrogen, boron, and silicon: a theoretical study

Institute of Scientific and Technical Information of China (English)

Dai Xian-Qi; Tang Ya-Nan; Dai Ya-Wei; Li Yan-Hui; Zhao Jian-Hua; Zhao Bao; Yang Zong-Xian

2011-01-01

The structures of Pt clusters on nitrogen-, boron-, silicon- doped graphenes are theoretically studied using densityfunctional theory. These dopants (nitrogen, boron and silicon) each do not induce a local curvature in the graphene and the doped graphenes all retain their planar form. The formation energy of the silicon-graphene system is lower than those of the nitrogen-, boron-doped graphenes, indicating that the silicon atom is easier to incorporate into the graphene.All the substitutional impurities enhance the interaction between the Pt atom and the graphene. The adsorption energy of a Pt adsorbed on the silicon-doped graphene is much higher than those on the nitrogen- and boron-doped graphenes.The doped silicon atom can provide more charges to enhance the Pt-graphene interaction and the formation of Pt clusters each with a large size. The stable structures of Pt clusters on the doped-graphenes are dimeric, triangle and tetrahedron with the increase of the Pt coverage. Of all the studied structures, the tetrahedron is the most stable cluster which has the least influence on the planar surface of doped-graphene.
Nitrogen induced ferromagnetism in Cobalt doped BaTiO3

Directory of Open Access Journals (Sweden)

Chandrima Mitra

2012-09-01

Full Text Available The electronic structure and magnetism of Cobalt doped BaTiO3 (BaTi1−xCoxO3 is investigated. Substitutional Nitrogen on an Oxygen site is found to play an important role in inducing net magnetic moments in the system. The presence of a Nitrogen atom as nearest neighbour to a Cobalt atom is crucial in producing spin splitting of both the Nitrogen and Cobalt states thereby introducing a net local magnetic moment. The introduction of Nitrogen is further found to enhance ferromagnetic interactions between Cobalt atoms.
Nanopores creation in boron and nitrogen doped polycrystalline graphene: A molecular dynamics study

Science.gov (United States)

Izadifar, Mohammadreza; Abadi, Rouzbeh; Nezhad Shirazi, Ali Hossein; Alajlan, Naif; Rabczuk, Timon

2018-05-01

In the present paper, molecular dynamic simulations have been conducted to investigate the nanopores creation on 10% of boron and nitrogen doped polycrystalline graphene by silicon and diamond nanoclusters. Two types of nanoclusters based on silicon and diamond are used to investigate their effect for the fabrication of nanopores. Therefore, three different diameter sizes of the clusters with five kinetic energies of 10, 50, 100, 300 and 500 eV/atom at four different locations in boron or nitrogen doped polycrystalline graphene nanosheets have been perused. We also study the effect of 3% and 6% of boron doped polycrystalline graphene with the best outcome from 10% of doping. Our results reveal that the diamond cluster with diameter of 2 and 2.5 nm fabricates the largest nanopore areas on boron and nitrogen doped polycrystalline graphene, respectively. Furthermore, the kinetic energies of 10 and 50 eV/atom can not fabricate nanopores in some cases for silicon and diamond clusters on boron doped polycrystalline graphene nanosheets. On the other hand, silicon and diamond clusters fabricate nanopores for all locations and all tested energies on nitrogen doped polycrystalline graphene. The area sizes of nanopores fabricated by silicon and diamond clusters with diameter of 2 and 2.5 nm are close to the actual area size of the related clusters for the kinetic energy of 300 eV/atom in all locations on boron doped polycrystalline graphene. The maximum area and the average maximum area of nanopores are fabricated by the kinetic energy of 500 eV/atom inside the grain boundary at the center of the nanosheet and in the corner of nanosheet with diameters of 2 and 3 nm for silicon and diamond clusters on boron and nitrogen doped polycrystalline graphene.
Nitrogen-Doped Graphene:Effects of nitrogen species on the properties of the vanadium redox flow battery

International Nuclear Information System (INIS)

Shi, Lang; Liu, Suqin; He, Zhen; Shen, Junxi

2014-01-01

Nitrogen-doped graphene nanosheets (NGS), prepared by a simple hydrothermal reaction of graphene oxide (GO) with urea as nitrogen source were studied as positive electrodes in vanadium redox flow battery (VRFB). The synthesized NGS with the nitrogen level as high as 10.12 atom% is proven to be a promising material for VRFB. The structures and electrochemical properties of the materials are investigated by scanning electron microscopy, X-ray photoelectron spectroscopy, cyclic voltammetry and electrochemical impendence spectroscopy. The results demonstrate that not only the nitrogen doping level but the nitrogen type in the NGS are significant for its catalytic activity towards the [VO] 2+ /[VO 2 ] + redox couple reaction. In more detail, among four types of nitrogen species (pyridinic-N, pyrrolic-N, quaternary-N, oxidic-N) doped into the graphene lattice, quaternary-N play mainly roles for improving the catalytic activity toward the [VO] 2+ /[VO 2 ] + couple reaction
Investigation of fluorine adsorption on nitrogen doped MgAl_2O_4 surface by first-principles

International Nuclear Information System (INIS)

Lv, Xiaojun; Xu, Zhenming; Li, Jie; Chen, Jiangan; Liu, Qingsheng

2016-01-01

Graphical abstract: First-principles calculations indicate that MgAl_2O_4 surface is fluorine-loving, but hydrophobic. N doped MgAl_2O_4 (100) surface structure shows the highest fluorine adsorption performance and fluorine atom is more preferentially adsorbed on the Mg-Al bridge site. The fluorine adsorption intensity follow this order: N doped MgAl_2O_4 (100) > Al_2O_3 (0001) > MgAl_2O_4 (100) > MgO (100). N doped MgAl_2O_4 is a promising candidate for fluorine removal. - Highlights: • MgAl_2O_4 surface is fluorine-loving, not hydrophilic. • Fluorine preferentially adsorbs on the Mg-Al bridge site. • Adsorption intensity follow this order: N doped MgAl_2O_4 > Al_2O_3 > MgAl_2O_4 > MgO. • Excellent adsorption performance attributes to electron compensation of N atom. • Nitrogen doped MgAl_2O_4 is a promising candidate for fluorine removal. - Abstract: The nature of fluorine adsorption on pure and N doped MgAl_2O_4 surface has been investigated by first-principles calculations based on the density functional theory. Calculated results indicate that MgAl_2O_4 surface is fluorine-loving, not hydrophilic. Nitrogen doped MgAl_2O_4 (100) surface shows the highest fluorine adsorption performance and fluorine atom preferentially adsorbs on the Mg-Al bridge site. The fluorine adsorption intensity follow this order: Nitrogen doped MgAl_2O_4 (100) > Al_2O_3 (0001) > MgAl_2O_4 (100) > MgO (100). In-depth PDOS analysis suggested that 2p orbitals of F atom strongly hybridized with 3s- and 3p-orbitals of Al atom contribute to its high adsorption intensity. According to the analysis of Hirshfeld charge, the excellent fluorine adsorption performance of nitrogen doped MgAl_2O_4 attributes to the electron compensation effect of nitrogen atom and strong electrostatic interactions. All these evidences demonstrate a fact nitrogen doped MgAl_2O_4 is a promising candidate for fluorine removal.
Changes of the electronic structure of the atoms of nitrogen in nitrogen-doped multiwalled carbon nanotubes under the influence of pulsed ion radiation

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Korusenko, P.M., E-mail: korusenko@obisp.oscsbras.ru [Omsk Scientific Centre, Siberian Branch, Russian Academy of Sciences, Karl Marx Avenue, 15, Omsk 644024 (Russian Federation); Bolotov, V.V.; Nesov, S.N.; Povoroznyuk, S.N. [Omsk Scientific Centre, Siberian Branch, Russian Academy of Sciences, Karl Marx Avenue, 15, Omsk 644024 (Russian Federation); Khailov, I.P. [Tomsk Polytechnic University, Lenin Ave. 2a, Tomsk 634028 (Russian Federation)

2015-09-01

With the use of X-ray photoelectron spectroscopy (XPS) there have been investigated the changes of the chemical state of nitrogen atoms in the structure of nitrogen-doped multiwalled carbon nanotubes (CN{sub x}-MWCNTs) resulting from the impact of pulsed ion beam at various parameters of the beam (energy density, number of pulses). It has been established that irradiation with the pulsed ion beam leads to a reduction of the total amount of nitrogen in CN{sub x} nanotubes. It has been shown that a single pulse irradiation of ion beam at the energy densities of 0.5, 1, 1.5 J/cm{sup 2} leads to restructuring of the nitrogen from pyridinic and pyrrolic configuration to graphitic state. Complete removal of nitrogen (pyridinic, pyrrolic, graphitic) embedded in the structure of the walls of CN{sub x} nanotubes occurs at ten pulses and 1.5 J/cm{sup 2}.

Nitrogen-doped titanium dioxide photocatalysts for visible response prepared by using organic compounds

Directory of Open Access Journals (Sweden)

Yoshio Nosaka, Masami Matsushita, Junichi Nishino and Atsuko Y. Nosaka

2005-01-01

Full Text Available In order to utilize visible light in photocatalytic reactions, nitrogen atoms were doped in commercially available photocatalytic TiO2 powders by using an organic compound such as urea and guanidine. Analysis by X-ray photoelectron spectroscopy (XPS indicated that N atoms were incorporated into two different sites of the bulk phase of TiO2. A significant shift of the absorption edge to a lower energy and a higher absorption in the visible light region were observed. These N-doped TiO2 powders exhibited photocatalytic activity for the decomposition of 2-propanol in aqueous solution under visible light irradiation. The photocatalytic activity increased with the decrease of doped N atoms in O site, while decreased with decrease of the other sites. Degradation of photocatalytic activity based on the release of nitrogen atoms was observed for the reaction in the aqueous suspension system.
First-principles study of structural and work function properties for nitrogen-doped single-walled carbon nanotubes

International Nuclear Information System (INIS)

Shao, Xiji; Li, Detian; Cai, Jianqiu; Luo, Haijun; Dong, Changkun

2016-01-01

Graphical abstract: - Highlights: • Substitutional nitrogen atom doping in capped (5, 5) SWNT is investigated. • Serious defects appear from breaks of C−N bonds with N contents of above 23.3 at.%. • Work function drops after N doping and may reach 4.1 eV. - Abstract: The structural and electronic properties of the capped (5, 5) single-walled carbon nanotube (SWNT), including the structural stability, the work function, and the charge transfer performance, are investigated for the substitutional nitrogen atom doping under different concentrations by first-principles density functional theory. The geometrical structure keeps almost intact with single or two N atom doping, while C−N bonds may break up with serious defects for N concentrations of 23.3 at.% and above. The SWNT remains metallic and the work function drops after doping due to the upward shift of Fermi level, leading to the increase of the electrical conductivity. N doping enhances the oxygen reduction activity stronger than N adsorption because of higher charge transfers.
Investigation of fluorine adsorption on nitrogen doped MgAl{sub 2}O{sub 4} surface by first-principles

Energy Technology Data Exchange (ETDEWEB)

Lv, Xiaojun; Xu, Zhenming [School of Metallurgy and Environment, Central South University, Changsha 410083 (China); Li, Jie, E-mail: 15216105346@163.com [School of Metallurgy and Environment, Central South University, Changsha 410083 (China); Chen, Jiangan [Faculty of Resource and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 (China); Liu, Qingsheng [Faculty of Metallurgical and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 (China)

2016-07-15

Graphical abstract: First-principles calculations indicate that MgAl{sub 2}O{sub 4} surface is fluorine-loving, but hydrophobic. N doped MgAl{sub 2}O{sub 4} (100) surface structure shows the highest fluorine adsorption performance and fluorine atom is more preferentially adsorbed on the Mg-Al bridge site. The fluorine adsorption intensity follow this order: N doped MgAl{sub 2}O{sub 4} (100) > Al{sub 2}O{sub 3} (0001) > MgAl{sub 2}O{sub 4} (100) > MgO (100). N doped MgAl{sub 2}O{sub 4} is a promising candidate for fluorine removal. - Highlights: • MgAl{sub 2}O{sub 4} surface is fluorine-loving, not hydrophilic. • Fluorine preferentially adsorbs on the Mg-Al bridge site. • Adsorption intensity follow this order: N doped MgAl{sub 2}O{sub 4} > Al{sub 2}O{sub 3} > MgAl{sub 2}O{sub 4} > MgO. • Excellent adsorption performance attributes to electron compensation of N atom. • Nitrogen doped MgAl{sub 2}O{sub 4} is a promising candidate for fluorine removal. - Abstract: The nature of fluorine adsorption on pure and N doped MgAl{sub 2}O{sub 4} surface has been investigated by first-principles calculations based on the density functional theory. Calculated results indicate that MgAl{sub 2}O{sub 4} surface is fluorine-loving, not hydrophilic. Nitrogen doped MgAl{sub 2}O{sub 4} (100) surface shows the highest fluorine adsorption performance and fluorine atom preferentially adsorbs on the Mg-Al bridge site. The fluorine adsorption intensity follow this order: Nitrogen doped MgAl{sub 2}O{sub 4} (100) > Al{sub 2}O{sub 3} (0001) > MgAl{sub 2}O{sub 4} (100) > MgO (100). In-depth PDOS analysis suggested that 2p orbitals of F atom strongly hybridized with 3s- and 3p-orbitals of Al atom contribute to its high adsorption intensity. According to the analysis of Hirshfeld charge, the excellent fluorine adsorption performance of nitrogen doped MgAl{sub 2}O{sub 4} attributes to the electron compensation effect of nitrogen atom and strong electrostatic interactions. All these
Rectifying Properties of a Nitrogen/Boron-Doped Capped-Carbon-Nanotube-Based Molecular Junction

International Nuclear Information System (INIS)

Zhao Peng; Zhang Ying; Wang Pei-Ji; Zhang Zhong; Liu De-Sheng

2011-01-01

Based on the non-equilibrium Green's function method and first-principles density functional theory calculations, we investigate the electronic transport properties of a nitrogen/boron-doped capped-single-walled carbon-nanotube-based molecular junction. Obvious rectifying behavior is observed and it is strongly dependent on the doping site. The best rectifying performance can be carried out when the nitrogen/boron atom dopes at a carbon site in the second layer. Moreover, the rectifying performance can be further improved by adjusting the distance between the C 60 nanotube caps. (condensed matter: electronic structure, electrical, magnetic, and optical properties)
Facile preparation of nitrogen-doped hierarchical porous carbon with high performance in supercapacitors

International Nuclear Information System (INIS)

Yan, Kun; Kong, Ling-Bin; Shen, Kui-Wen; Dai, Yan-Hua; Shi, Ming; Hu, Bing; Luo, Yong-Chun; Kang, Long

2016-01-01

Graphical abstract: Preparing and activating process of nitrogen-doped hierarchical porous carbon (NHPC). - Highlights: • The well-defined PAN-b-PMMA copolymer was synthesized by atom transfer radical polymerization with narrow molecular weight distribution. • Nitrogen-doped hierarchical porous structure (NHPC) was prepared through a simple carbonization procedure of PAN-b-PMMA precursor. • NHPC possessed hierarchical porous structure with high BET surface area of 257 m"2 g"−"1 and DFT mesopore size of 14.61 nm. • Effects of activation conditions on supercapacitive behavior were systematically studied. - Abstract: The nitrogen-doped hierarchical porous carbon (NHPC) material was successfully prepared through a simple carbonization procedure of well-defined diblock copolymer precursor containing nitrogen-enriched carbon source, i.e., polyacrylonitrile (PAN), and asacrificial block, i.e., polymethylmethacrylate (PMMA). PAN-b-PMMA diblock copolymer was synthesized by atom transfer radical polymeriation (ATRP) with narrow molecular weight distribution. The as-obtained NHPC possessed nitrogen-doped hierarchical porous structure with high BET surface area of 257 m"2 g"−"1 and Nonlocal density functional theory (NLDFT) mesopore size of 14.61 nm. Surface activated nitrogen-doped hierarchical porous carbon (A-NHPC) materials were obtained by subsequent surface activation with HNO_3 solution. The effects of activation conditions on supercapacitive behavior were systematically studied, a maximum specific capacitance of 314 F g"−"1 at a current density of 0.5 A g"−"1 was achieved in 2 M KOH aqueous electrolyte. Simultaneously, it exhibited excellent rate capability of 67.8% capacitance retention as the current density increased from 0.5 to 20 A g"−"1 and superior cycling performance of 90% capacitance retention after 10,000 cycles at the current density of 2 A g"−"1.
Facile preparation of nitrogen-doped hierarchical porous carbon with high performance in supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Yan, Kun [State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050 (China); Kong, Ling-Bin, E-mail: konglb@lut.cn [State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050 (China); School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050 (China); Shen, Kui-Wen; Dai, Yan-Hua; Shi, Ming; Hu, Bing [State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050 (China); Luo, Yong-Chun; Kang, Long [School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050 (China)

2016-02-28

Graphical abstract: Preparing and activating process of nitrogen-doped hierarchical porous carbon (NHPC). - Highlights: • The well-defined PAN-b-PMMA copolymer was synthesized by atom transfer radical polymerization with narrow molecular weight distribution. • Nitrogen-doped hierarchical porous structure (NHPC) was prepared through a simple carbonization procedure of PAN-b-PMMA precursor. • NHPC possessed hierarchical porous structure with high BET surface area of 257 m{sup 2} g{sup −1} and DFT mesopore size of 14.61 nm. • Effects of activation conditions on supercapacitive behavior were systematically studied. - Abstract: The nitrogen-doped hierarchical porous carbon (NHPC) material was successfully prepared through a simple carbonization procedure of well-defined diblock copolymer precursor containing nitrogen-enriched carbon source, i.e., polyacrylonitrile (PAN), and asacrificial block, i.e., polymethylmethacrylate (PMMA). PAN-b-PMMA diblock copolymer was synthesized by atom transfer radical polymeriation (ATRP) with narrow molecular weight distribution. The as-obtained NHPC possessed nitrogen-doped hierarchical porous structure with high BET surface area of 257 m{sup 2} g{sup −1} and Nonlocal density functional theory (NLDFT) mesopore size of 14.61 nm. Surface activated nitrogen-doped hierarchical porous carbon (A-NHPC) materials were obtained by subsequent surface activation with HNO{sub 3} solution. The effects of activation conditions on supercapacitive behavior were systematically studied, a maximum specific capacitance of 314 F g{sup −1} at a current density of 0.5 A g{sup −1} was achieved in 2 M KOH aqueous electrolyte. Simultaneously, it exhibited excellent rate capability of 67.8% capacitance retention as the current density increased from 0.5 to 20 A g{sup −1} and superior cycling performance of 90% capacitance retention after 10,000 cycles at the current density of 2 A g{sup −1}.
Three-Dimensional Porous Nitrogen-Doped NiO Nanostructures as Highly Sensitive NO2 Sensors

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Van Hoang Luan

2017-10-01

Full Text Available Nickel oxide has been widely used in chemical sensing applications, because it has an excellent p-type semiconducting property with high chemical stability. Here, we present a novel technique of fabricating three-dimensional porous nitrogen-doped nickel oxide nanosheets as a highly sensitive NO2 sensor. The elaborate nanostructure was prepared by a simple and effective hydrothermal synthesis method. Subsequently, nitrogen doping was achieved by thermal treatment with ammonia gas. When the p-type dopant, i.e., nitrogen atoms, was introduced in the three-dimensional nanostructures, the nickel-oxide-nanosheet-based sensor showed considerable NO2 sensing ability with two-fold higher responsivity and sensitivity compared to non-doped nickel-oxide-based sensors.
Nitrogen-doped graphene as transparent counter electrode for efficient dye-sensitized solar cells

International Nuclear Information System (INIS)

Wang, Guiqiang; Fang, Yanyan; Lin, Yuan; Xing, Wei; Zhuo, Shuping

2012-01-01

Graphical abstract: Display Omitted Highlights: ► NG sheets are prepared through a hydrothermal reduction of graphite oxide. ► The transparent NG counter electrodes of DSCs are fabricated at room temperature. ► Transparent NG electrode exhibits excellent catalytic activity for the reduction of I 3 − . ► The DSC with NG electrode achieves a comparable efficiency to that of the Pt-based cell. ► The efficiency of rear illumination is about 85% that of front illumination. -- Abstract: Nitrogen-doped graphene sheets are prepared through a hydrothermal reduction of graphite oxide in the presence of ammonia and applied to fabricate the transparent counter electrode of dye-sensitized solar cells. The atomic percentage of nitrogen in doped graphene sample is about 2.5%, and the nitrogen bonds display pyridine and pyrrole-like configurations. Cyclic voltammetry studies demonstrate a much higher electrocatalytic activity toward I − /I 3 − redox reaction for nitrogen-doped graphene, as compared with pristine graphene. The dye-sensitized solar cell with this transparent nitrogen-doped graphene counter electrode shows conversion efficiencies of 6.12% and 5.23% corresponding to front-side and rear-side illumination, respectively. Meanwhile, the cell with a Pt counter electrode shows a conversion efficiency of 6.97% under the same experimental condition. These promising results highlight the potential application of nitrogen-doped graphene in cost-effective, transparent dye-sensitized solar cells.
How lithium atoms affect the first hyperpolarizability of BN edge-doped graphene.

Science.gov (United States)

Song, Yao-Dong; Wu, Li-Ming; Chen, Qiao-Ling; Liu, Fa-Kun; Tang, Xiao-Wen

2016-01-01

How do lithium atoms affect the first hyperpolarizability (β0) of boron-nitrogen (BN) edge-doped graphene. In this work, using pentacene as graphene model, Lin@BN-1 edge-doped pentacene and Lin@BN-2 edge-doped pentacene (n = 1, 5) were designed to study this problem. First, two models (BN-1 edge-doped pentacene, and BN-2 edge-doped pentacene ) were formed by doping the BN into the pentacene with different order, and then Li@BN-1 edge-doped pentacene and Li@ BN-2 edge-doped pentacene were obtained by substituting the H atom in BN edge-doped pentacene with a Li atom. The results show that the first hyperpolarizabilities of BN-1 edge-doped pentacene and Li@BN-1 edge-doped pentacene were 4059 a.u. and 6249 a.u., respectively; the first hyperpolarizabilities of BN-2 edge-doped pentacene and Li@BN-2 edge-doped pentacene were 2491 a.u. and 4265 a.u., respectively. The results indicate that the effect of Li substitution is to greatly increase the β0 value. To further enhance the first hyperpolarizability, Li5@ BN-1 edge-doped pentacene and Li5@BN-2 edge-doped pentacene were designed, and were found to exhibit considerably larger first hyperpolarizabilities (β0) (12,112 a.u. and 7921a.u., respectively). This work may inspire further study of the nonlinear properties of BN edge-doped graphene.
Effect of nitrogen precursors on the electrochemical performance of nitrogen-doped reduced graphene oxide towards oxygen reduction reaction

International Nuclear Information System (INIS)

Soo, Li Ting; Loh, Kee Shyuan; Mohamad, Abu Bakar; Daud, Wan Ramli Wan; Wong, Wai Yin

2016-01-01

A series of nitrogen-doped reduced graphene oxides (NGs) with different ratios are synthesized by thermal annealing of graphene oxide with melamine or urea. The total nitrogen content in NG is high, with values of up to 5.88 at.%. The NG samples prepared by melamine exhibited thin transparent graphene sheets structure, with consist of higher nitrogen doping level and quaternary N content compared to those NG samples prepared from urea. Electrochemical characterizations show that NG is a promising metal-free electrocatalyst for an oxygen reduction reaction (ORR). Incorporation of nitrogen atoms into graphene basal plane can enhances its electrocatalytic activity toward ORR in alkaline media. The onset potential and mean number of electron transfers on NG 1 are −0.10 V and 3.80 respectively, which is higher than that of reduced graphene oxide (−0.15 V, 3.52). This study suggests that quaternary-N of the NG samples is the active site which determines the ORR activity Moreover, the NG samples with the transparent layer of graphene-like structure have better ORR performances than that of bulk graphite-like NG samples. - Highlights: • Synthesis of nitrogen-doped graphene (NG) via thermal annealing. • The effects of the nitrogen precursors on the synthesized NG are discussed. • Electrochemical performances of the NG are correlated to N doping and EASA. • Graphitic-N is proposed to be the active site for ORR.
Effect of nitrogen precursors on the electrochemical performance of nitrogen-doped reduced graphene oxide towards oxygen reduction reaction

Energy Technology Data Exchange (ETDEWEB)

Soo, Li Ting, E-mail: nicolesoo90@gmail.com [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); Loh, Kee Shyuan, E-mail: ksloh@ukm.edu.my [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); Mohamad, Abu Bakar, E-mail: drab@ukm.edu.my [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); Daud, Wan Ramli Wan, E-mail: wramli@ukm.edu.my [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); Wong, Wai Yin, E-mail: waiyin.wwy@gmail.com [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); School of Engineering, Taylor' s University' s Lakeside Campus, No. 1, Jalan Taylor' s, 46500 Subang Jaya, Selangor (Malaysia)

2016-08-25

A series of nitrogen-doped reduced graphene oxides (NGs) with different ratios are synthesized by thermal annealing of graphene oxide with melamine or urea. The total nitrogen content in NG is high, with values of up to 5.88 at.%. The NG samples prepared by melamine exhibited thin transparent graphene sheets structure, with consist of higher nitrogen doping level and quaternary N content compared to those NG samples prepared from urea. Electrochemical characterizations show that NG is a promising metal-free electrocatalyst for an oxygen reduction reaction (ORR). Incorporation of nitrogen atoms into graphene basal plane can enhances its electrocatalytic activity toward ORR in alkaline media. The onset potential and mean number of electron transfers on NG 1 are −0.10 V and 3.80 respectively, which is higher than that of reduced graphene oxide (−0.15 V, 3.52). This study suggests that quaternary-N of the NG samples is the active site which determines the ORR activity Moreover, the NG samples with the transparent layer of graphene-like structure have better ORR performances than that of bulk graphite-like NG samples. - Highlights: • Synthesis of nitrogen-doped graphene (NG) via thermal annealing. • The effects of the nitrogen precursors on the synthesized NG are discussed. • Electrochemical performances of the NG are correlated to N doping and EASA. • Graphitic-N is proposed to be the active site for ORR.
Controllable nitrogen doping in as deposited TiO{sub 2} film and its effect on post deposition annealing

Energy Technology Data Exchange (ETDEWEB)

Deng, Shaoren; Devloo-Casier, Kilian; Devulder, Wouter; Dendooven, Jolien; Deduytsche, Davy; Detavernier, Christophe, E-mail: Christophe.Detavernier@ugent.be [Department of Solid State Sciences, Ghent University, Krijgslaan 281/S1, B-9000 Gent (Belgium); Verbruggen, Sammy W. [Department of Bio-Engineering Sciences, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium and Center for Surface Chemistry and Catalysis, KU Leuven, Kasteelpark Arenberg 23, B-3001 Heverlee (Belgium); Lenaerts, Silvia [Department of Bio-Engineering Sciences, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Martens, Johan A. [Center for Surface Chemistry and Catalysis, KU Leuven, Kasteelpark Arenberg 23, B-3001 Heverlee (Belgium); Van den Berghe, Sven [SCK-CEN, Boeretang 200, B-2400 Mol (Belgium)

2014-01-15

In order to narrow the band gap of TiO{sub 2}, nitrogen doping by combining thermal atomic layer deposition (TALD) of TiO{sub 2} and plasma enhanced atomic layer deposition (PEALD) of TiN has been implemented. By altering the ratio between TALD TiO{sub 2} and PEALD TiN, the as synthesized TiO{sub x}N{sub y} films showed different band gaps (from 1.91 eV to 3.14 eV). In situ x-ray diffraction characterization showed that the crystallization behavior of these films changed after nitrogen doping. After annealing in helium, nitrogen doped TiO{sub 2} films crystallized into rutile phase while for the samples annealed in air a preferential growth of the anatase TiO{sub 2} along (001) orientation was observed. Photocatalytic tests of the degradation of stearic acid were done to evaluate the effect of N doping on the photocatalytic activity.
Nitrogen Doped Ordered Mesoporous Carbon as Support of PtRu Nanoparticles for Methanol Electro-Oxidation

Directory of Open Access Journals (Sweden)

David Sebastián

2018-04-01

Full Text Available The low oxidation kinetics of alcohols and the need for expensive platinum group metals are still some of the main drawbacks for the commercialization of energy efficient direct alcohol fuel cells. In this work, we investigate the influence of nitrogen doping of ordered mesoporous carbon (CMK as support on the electrochemical activity of PtRu nanoparticles. Nitrogen doping procedures involve the utilization of pyrrole as both nitrogen and carbon precursor by means of a templating method using mesoporous silica. This method allows obtaining carbon supports with up to 14 wt. % nitrogen, with an effective introduction of pyridinic, pyrrolic and quaternary nitrogen. PtRu nanoparticles were deposited by sodium formate reduction method. The presence of nitrogen mainly influences the Pt:Ru atomic ratio at the near surface, passing from 50:50 on the bare (un-doped CMK to 70:30 for the N-doped CMK catalyst. The electroactivity towards the methanol oxidation reaction (MOR was evaluated in acid and alkaline electrolytes. The presence of nitrogen in the support favors a faster oxidation of methanol due to the enrichment of Pt at the near surface together with an increase of the intrinsic activity of PtRu nanoparticles.
Nitrogen-doped carbon aerogels for electrical energy storage

Science.gov (United States)

Campbell, Patrick; Montalvo, Elizabeth; Baumann, Theodore F.; Biener, Juergen; Merrill, Matthew; Reed, Eric W.; Worsley, Marcus A.

2017-10-03

Disclosed here is a method for making a nitrogen-doped carbon aerogel, comprising: preparing a reaction mixture comprising formaldehyde, at least one nitrogen-containing resorcinol analog, at least one catalyst, and at least one solvent; curing the reaction mixture to produce a wet gel; drying the wet gel to produce a dry gel; and thermally annealing the dry gel to produce the nitrogen-doped carbon aerogel. Also disclosed is a nitrogen-doped carbon aerogel obtained according to the method and a supercapacitor comprising the nitrogen-doped carbon aerogel.
Theoretical study of nitrogen-doped graphene nanoflakes: Stability and spectroscopy depending on dopant types and flake sizes.

Science.gov (United States)

Lin, Chih-Kai

2018-03-05

As nitrogen-doped graphene has been widely applied in optoelectronic devices and catalytic reactions, in this work we have investigated where the nitrogen atoms tend to reside in the material and how they affect the electron density and spectroscopic properties from a theoretical point of view. DFT calculations on N-doped hexagonal and rectangular graphene nanoflakes (GNFs) showed that nitrogen atoms locating on zigzag edges are obviously more stable than those on armchair edges or inside flakes, and interestingly, the N-hydrogenated pyridine moiety could be preferable to pure pyridine moiety in large models. The UV-vis absorption spectra of these nitrogen-doped GNFs display strong dependence on flake sizes, where the larger flakes have their major peaks in lower energy ranges. Moreover, the spectra exhibit different connections to various dopant types and positions: the graphitic-type dopant species present large variety in absorption profiles, while the pyridinic-type ones show extraordinary uniform stability and spectra independent of dopant positions/numbers and hence are hardly distinguishable from each other. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.
Thermal conductivity and heat transport properties of nitrogen-doped graphene.

Science.gov (United States)

Goharshadi, Elaheh K; Mahdizadeh, Sayyed Jalil

2015-11-01

In the present study, the thermal conductivity (TC) and heat transport properties of nitrogen doped graphene (N-graphene) were investigated as a function of temperature (107-400K) and N-doped concentration (0.0-7.0%) using equilibrium molecular dynamics simulation based on Green-Kubo method. According to the results, a drastic decline in TC of graphene observed at very low N-doped concentration (0.5 and 1.0%). Substitution of just 1.0% of carbon atoms with nitrogens causes a 77.2, 65.4, 59.2, and 53.7% reduction in TC at 107, 200, 300, and 400K, respectively. The values of TC of N-graphene at different temperatures approach to each other as N-doped concentration increases. The results also indicate that TC of N-graphene is much less sensitive to temperature compared with pristine graphene and the sensitivity decreases as N-doped concentration increases. The phonon-phonon scattering relaxation times and the phonon mean free path of phonons were also calculated. The contribution of high frequency optical phonons for pristine graphene and N-graphene with 7.0% N-doped concentration is 0-2% and 4-8%, respectively. These findings imply that it is potentially feasible to control heat transfer on the nanoscale when designing N-graphene based thermal devices. Copyright © 2015 Elsevier Inc. All rights reserved.
Theoretical Investigation on Single-Wall Carbon Nanotubes Doped with Nitrogen, Pyridine-Like Nitrogen Defects, and Transition Metal Atoms

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Michael Mananghaya

2012-01-01

Full Text Available This study addresses the inherent difficulty in synthesizing single-walled carbon nanotubes (SWCNTs with uniform chirality and well-defined electronic properties through the introduction of dopants, topological defects, and intercalation of metals. Depending on the desired application, one can modify the electronic and magnetic properties of SWCNTs through an appropriate introduction of imperfections. This scheme broadens the application areas of SWCNTs. Under this motivation, we present our ongoing investigations of the following models: (i (10, 0 and (5, 5 SWCNT doped with nitrogen (CNxNT, (ii (10, 0 and (5, 5 SWCNT with pyridine-like defects (3NV-CNxNT, (iii (10, 0 SWCNT with porphyrine-like defects (4ND-CNxNT. Models (ii and (iii were chemically functionalized with 14 transition metals (TMs: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pd, Ag, Pt and Au. Using the spin-unrestricted density functional theory (DFT, stable configurations, deformations, formation and binding energies, the effects of the doping concentration of nitrogen, pyridine-like and porphyrine-like defects on the electronic properties were all examined. Results reveal that the electronic properties of SWCNTs show strong dependence on the concentration and configuration of nitrogen impurities, its defects, and the TMs adsorbed.
Heavily nitrogen doped, graphene supercapacitor from silk cocoon

International Nuclear Information System (INIS)

Sahu, Vikrant; Grover, Sonia; Tulachan, Brindan; Sharma, Meenakshi; Srivastava, Gaurav; Roy, Manas; Saxena, Manav; Sethy, Niroj; Bhargava, Kalpana; Philip, Deepu; Kim, Hansung; Singh, Gurmeet; Singh, Sushil Kumar; Das, Mainak; Sharma, Raj Kishore

2015-01-01

Doping of graphene with nitrogen is of much interest, since it improves the overall conductivity and supercapacitive properties. Besides conductivity, nitrogen doping also enhances the pseudo-capacitance due to fast and reversible surface redox processes. In this work, we have developed a cheap and easy process for synthesizing heavily nitrogen doped graphene (15% nitrogen) from non-mulberry silk cocoon membrane (Tassar, Antheraea mylitta) by pyrolyzing the cocoon at 400 °C in argon atmosphere. Further we have investigated the performance of this heavily ‘nitrogen doped graphene’ (NDG) in a supercapacitor device. Our results suggest that NDG obtained from cocoon has improved supercapacitor performance. The improved performance is due to the high electronegativity of nitrogen that forms dipoles on the graphene surface. These dipoles consequently enhance the tendency of graphene to attract charged species to its surface. This is a green and clean synthesis approach for developing electronic materials for energy applications
Highly enhanced electrochemical activity of Ni foam electrodes decorated with nitrogen-doped carbon nanotubes for non-aqueous redox flow batteries

Science.gov (United States)

Lee, Jungkuk; Park, Min-Sik; Kim, Ki Jae

2017-02-01

Nitrogen-doped carbon nanotubes (NCNTs) are directly grown on the surface of a three-dimensional (3D) Ni foam substrate by floating catalytic chemical vapor deposition (FCCVD). The electrochemical properties of the 3D NCNT-Ni foam are thoroughly examined as a potential electrode for non-aqueous redox flow batteries (RFBs). During synthesis, nitrogen atoms can be successfully doped onto the carbon nanotube (CNT) lattices by forming an abundance of nitrogen-based functional groups. The 3D NCNT-Ni foam electrode exhibits excellent electrochemical activities toward the redox reactions of [Fe (bpy)3]2+/3+ (in anolyte) and [Co(bpy)3]+/2+ (in catholyte), which are mainly attributed to the hierarchical 3D structure of the NCNT-Ni foam electrode and the catalytic effect of nitrogen atoms doped onto the CNTs; this leads to faster mass transfer and charge transfer during operation. As a result, the RFB cell assembled with 3D NCNT-Ni foam electrodes exhibits a high energy efficiency of 80.4% in the first cycle; this performance is maintained up to the 50th cycle without efficiency loss.
Undoped TiO2 and nitrogen-doped TiO2 thin films deposited by atomic layer deposition on planar and architectured surfaces for photovoltaic applications

International Nuclear Information System (INIS)

Tian, Liang; Soum-Glaude, Adurey; Volpi, Fabien; Salvo, Luc; Berthomé, Grégory; Coindeau, Stéphane; Mantoux, Arnaud; Boichot, Raphaël; Lay, Sabine; Brizé, Virginie; Blanquet, Elisabeth; Giusti, Gaël; Bellet, Daniel

2015-01-01

Undoped and nitrogen doped TiO 2 thin films were deposited by atomic layer deposition on planar substrates. Deposition on 3D-architecture substrates made of metallic foams was also investigated to propose architectured photovoltaic stack fabrication. All the films were deposited at 265 °C and nitrogen incorporation was achieved by using titanium isopropoxide, NH 3 and/or N 2 O as precursors. The maximum nitrogen incorporation level obtained in this study was 2.9 at. %, resulting in films exhibiting a resistivity of 115 Ω cm (+/−10 Ω cm) combined with an average total transmittance of 60% in the 400–1000 nm wavelength range. Eventually, TiO 2 thin films were deposited on the 3D metallic foam template

Preparation of nitrogen-doped carbon tubes

Science.gov (United States)

Chung, Hoon Taek; Zelenay, Piotr

2015-12-22

A method for synthesizing nitrogen-doped carbon tubes involves preparing a solution of cyanamide and a suitable transition metal-containing salt in a solvent, evaporating the solvent to form a solid, and pyrolyzing the solid under an inert atmosphere under conditions suitable for the production of nitrogen-doped carbon tubes from the solid. Pyrolyzing for a shorter period of time followed by rapid cooling resulted in a tubes with a narrower average diameter.
A computational study on tuning the field emission and electronic properties of BN nanocones by impurity atom doping

Science.gov (United States)

Ahmadi, S.; Delir Kheirollahi Nezhad, P.; Hosseinian, A.; Vessally, E.

2018-06-01

We have inspected the effect of substituting a boron or nitrogen atom of a BN nanocone (BNNC) by two impurity atoms with lower and higher atomic numbers based on the density functional theory calculations. Our results explain the experimental observations in a molecular level. Orbital and partial density of states analyses show that the doping processes increase the electrical conductivity by creating new states within the gap of BNNC as follows: BeB > ON > CB > CN. The electron emission current from the surface of BNNC is improved after the CB and BeB dopings, and it is decreased by CN and ON dopings. The BeB and CN dopings make the BNNC a p-type semiconductor and the CB and ON dopings make it an n-type one in good agreement with the experimental results. The ON and BeB doping processes are suggested for the field emission current, and electrical conductivity enhancement, respectively.
Nitrogen-doped graphene network supported copper nanoparticles encapsulated with graphene shells for surface-enhanced Raman scattering

Science.gov (United States)

Zhang, Xiang; Shi, Chunsheng; Liu, Enzuo; Li, Jiajun; Zhao, Naiqin; He, Chunnian

2015-10-01

In this study, we demonstrated nitrogen-doped graphene network supported few-layered graphene shell encapsulated Cu nanoparticles (NPs) (Cu@G-NGNs) as a sensing platform, which were constructed by a simple and scalable in situ chemical vapor deposition (CVD) technique with the assistance of a self-assembled three-dimensional (3D) NaCl template. Compared with pure Cu NPs and graphene decorated Cu NPs, the graphene shells can strengthen the plasmonic coupling between graphene and Cu, thereby contributing to an obvious improvement in the local electromagnetic field that was validated by finite element numerical simulations, while the 3D nitrogen-doped graphene walls with a large surface area facilitated molecule adsorption and the doped nitrogen atoms embedded in the graphene lattice can reduce the surface energy of the system. With these merits, a good surface enhanced Raman spectroscopy (SERS) activity of the 3D Cu@G-NGN painting film on glass was demonstrated using rhodamine 6G and crystal violet as model analytes, exhibiting a satisfactory sensitivity, reproducibility and stability. As far as we know, this is the first report on the in situ synthesis of nitrogen-doped graphene/copper nanocomposites and this facile and low-cost Cu-based strategy tends to be a good supplement to Ag and Au based substrates for SERS applications.In this study, we demonstrated nitrogen-doped graphene network supported few-layered graphene shell encapsulated Cu nanoparticles (NPs) (Cu@G-NGNs) as a sensing platform, which were constructed by a simple and scalable in situ chemical vapor deposition (CVD) technique with the assistance of a self-assembled three-dimensional (3D) NaCl template. Compared with pure Cu NPs and graphene decorated Cu NPs, the graphene shells can strengthen the plasmonic coupling between graphene and Cu, thereby contributing to an obvious improvement in the local electromagnetic field that was validated by finite element numerical simulations, while the 3D nitrogen-doped
Synthesis of nitrogen-doped graphene via solid microwave method

Energy Technology Data Exchange (ETDEWEB)

Zhang, Li, E-mail: zhangli379@sohu.com [School of Electrical Engineering, Dalian University of Technology, Dalian, Liaoning 116024 (China); Ji, Bingcheng, E-mail: debbo.jee@outlook.com [School of Electrical Engineering, Dalian University of Technology, Dalian, Liaoning 116024 (China); Wang, Kai [School of Electrical Engineering, Dalian University of Technology, Dalian, Liaoning 116024 (China); Song, Jinyan [School of Information Engineering, Dalian Ocean University, Dalian, Liaoning 116024 (China)

2014-07-01

Graphical abstract: - Highlights: • A direct solid microwave method is developed to prepare nitrogen-doped graphene. • The method consists of two steps, namely the functionalization and microwave irradiation. • Melamine can serve as not only functionalizing agent but also nitrogen source. - Abstract: In this paper, we propose a solid microwave-mediated method for scalable production of nitrogen-doped graphene sheets (NGS) using low-cost industrial material melamine as functionalizing agent and nitrogen source. The strong interaction of microwaves with graphene oxide has been fully utilized to generate in situ heating that induces the decompose melamine and nitrogen doping of graphene. The morphology, structure, and components of the as-produced nitrogen-doped graphene are characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Brunauer–Emmett–Teller (BET), pore-size distribution (PSD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectra (XPS), X-ray diffraction (XRD), and Raman spectroscopy. The results show NGS can be successfully synthesized via this strategy.
Synthesis of nitrogen-doped graphene via solid microwave method

International Nuclear Information System (INIS)

Zhang, Li; Ji, Bingcheng; Wang, Kai; Song, Jinyan

2014-01-01

Graphical abstract: - Highlights: • A direct solid microwave method is developed to prepare nitrogen-doped graphene. • The method consists of two steps, namely the functionalization and microwave irradiation. • Melamine can serve as not only functionalizing agent but also nitrogen source. - Abstract: In this paper, we propose a solid microwave-mediated method for scalable production of nitrogen-doped graphene sheets (NGS) using low-cost industrial material melamine as functionalizing agent and nitrogen source. The strong interaction of microwaves with graphene oxide has been fully utilized to generate in situ heating that induces the decompose melamine and nitrogen doping of graphene. The morphology, structure, and components of the as-produced nitrogen-doped graphene are characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Brunauer–Emmett–Teller (BET), pore-size distribution (PSD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectra (XPS), X-ray diffraction (XRD), and Raman spectroscopy. The results show NGS can be successfully synthesized via this strategy
The fundamental science of nitrogen-doping of niobium superconducting cavities

Science.gov (United States)

Gonnella, Daniel Alfred

Doping of niobium superconducting RF cavities with impurities has been demonstrated to have the ability to significantly improve the cryogenic efficiency of the accelerating structures. Doping SRF cavities with nitrogen is a relatively simple additional step to cavity preparation that can make drastic improvements in a cavity's intrinsic quality factor, Q0. Nitrogen-doping consists of treating SRF cavities at high temperatures in a low nitrogen-atmosphere. This leads to two important effects: an improvement in Q0 at low fields, and the presence of an "anti-Q slope" in which the cryogenic efficiency of doped cavities actually improves at higher fields. After its initial discovery, nitrogen-doping showed real promise but many fundamental scientific questions remained about the process. Nitrogen-doped cavities consistently quenched at lower fields than un-doped cavities, cooling the cavities through their critical temperature slowly led to poor performance, and the mechanism behind the Q0 improvement was not well understood. This dissertation focuses on addressing these issues. Single-cell 1.3 GHz cavities were prepared with different nitrogen-dopings and their effects studied systematically. It was found that nitrogen-doping drastically lowers the mean free path of the RF penetration layer of the niobium, leading to a lowering of the temperature-dependent BCS resistance, RBCS, at low fields. Theoretical work to predict the anti-Q slope was compared with experimental results to more fundamentally understand the nature of the field dependence of RBCS. Nitrogen-doped cavities were found to have a much larger sensitivity of residual resistance from trapped magnetic flux than un-doped cavities. Fast cool downs with large spatial temperature gradients through Tc were found to more efficiently expel magnetic flux. The full dependence of this sensitivity to trapped magnetic flux was studied as a function of changing mean free path and found to be in good agreement with
Revealing the Origin of Activity in Nitrogen-Doped Nanocarbons towards Electrocatalytic Reduction of Carbon Dioxide.

Science.gov (United States)

Xu, Junyuan; Kan, Yuhe; Huang, Rui; Zhang, Bingsen; Wang, Bolun; Wu, Kuang-Hsu; Lin, Yangming; Sun, Xiaoyan; Li, Qingfeng; Centi, Gabriele; Su, Dangsheng

2016-05-23

Carbon nanotubes (CNTs) are functionalized with nitrogen atoms for reduction of carbon dioxide (CO2 ). The investigation explores the origin of the catalyst's activity and the role of nitrogen chemical states therein. The catalysts show excellent performances, with about 90 % current efficiency for CO formation and stability over 60 hours. The Tafel analyses and density functional theory calculations suggest that the reduction of CO2 proceeds through an initial rate-determining transfer of one electron to CO2 , which leads to the formation of carbon dioxide radical anion (CO2 (.-) ). The initial reduction barrier is too high on pristine CNTs, resulting in a very high overpotentials at which the hydrogen evolution reaction dominates over CO2 reduction. The doped nitrogen atoms stabilize the radical anion, thereby lowering the initial reduction barrier and improving the intrinsic activity. The most efficient nitrogen chemical state for this reaction is quaternary nitrogen, followed by pyridinic and pyrrolic nitrogen. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Atmospheric pressure route to epitaxial nitrogen-doped trilayer graphene on 4H-SiC (0001) substrate

International Nuclear Information System (INIS)

Boutchich, M.; Arezki, H.; Alamarguy, D.; Güneş, F.; Alvarez, J.; Kleider, J. P.; Ho, K.-I.; Lai, C. S.; Sediri, H.; Ouerghi, A.

2014-01-01

Large-area graphene film doped with nitrogen is of great interest for a wide spectrum of nanoelectronics applications, such as field effect devices, super capacitors, and fuel cells among many others. Here, we report on the structural and electronic properties of nitrogen doped trilayer graphene on 4H-SiC (0001) grown under atmospheric pressure. The trilayer nature of the growth is evidenced by scanning transmission electron microscopy. X-ray photoelectron spectroscopy shows the incorporation of 1.2% of nitrogen distributed in pyrrolic-N, and pyridinic-N configurations as well as a graphitic-N contribution. This incorporation causes an increase in the D band on the Raman signature indicating that the nitrogen is creating defects. Ultraviolet photoelectron spectroscopy shows a decrease of the work function of 0.3 eV due to the N-type doping of the nitrogen atoms in the carbon lattice and the edge defects. A top gate field effect transistor device has been fabricated and exhibits carrier mobilities up to 1300 cm 2 /V s for holes and 850 cm 2 /V s for electrons at room temperature
Defect concentration in nitrogen-doped graphene grown on Cu substrate: A thickness effect

Energy Technology Data Exchange (ETDEWEB)

Sharma, Dhananjay K., E-mail: dhananjay@ua.pt [Department of Physics & CICECO – Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro (Portugal); Department of Mechanical Engineering & Centre for Mechanical Technology & Automation, University of Aveiro, 3810-193 Aveiro (Portugal); Fateixa, Sara [Department of Chemistry & CICECO – Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro (Portugal); Hortigüela, María J. [Department of Mechanical Engineering & Centre for Mechanical Technology & Automation, University of Aveiro, 3810-193 Aveiro (Portugal); Vidyasagar, Reddithota [Department of Physics & CICECO – Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro (Portugal); Otero-Irurueta, Gonzalo [Department of Mechanical Engineering & Centre for Mechanical Technology & Automation, University of Aveiro, 3810-193 Aveiro (Portugal); Nogueira, Helena I.S. [Department of Chemistry & CICECO – Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro (Portugal); Singh, Manoj Kumar [Department of Mechanical Engineering & Centre for Mechanical Technology & Automation, University of Aveiro, 3810-193 Aveiro (Portugal); Kholkin, Andrei, E-mail: kholkin@ua.pt [Department of Physics & CICECO – Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro (Portugal); School of Natural Sciences and Mathematics, Ural Federal University, 620000 Ekaterinburg (Russian Federation)

2017-05-15

Tuning the band-gap of graphene is a current need for real device applications. Copper (Cu) as a substrate plays a crucial role in graphene deposition. Here we report the fabrication of in-situ nitrogen (N) doped graphene via chemical vapor deposition (CVD) technique and the effect of Cu substrate thickness on the growth mechanism. The ratio of intensities of G and D peaks was used to evaluate the defect concentration based on local activation model associated with the distortion of the crystal lattice due to incorporation of nitrogen atoms into graphene lattice. The results suggest that Cu substrate of 20 µm in thickness exhibits higher defect density (1.86×10{sup 12} cm{sup −2}) as compared to both 10 and 25 µm thick substrates (1.23×10{sup 12} cm{sup −2} and 3.09×10{sup 11} cm{sup −2}, respectively). Furthermore, High Resolution -X-ray Photoelectron Spectroscopy (HR-XPS) precisely affirms ~0.4 at% of nitrogen intercalations in graphene. Our results show that the substitutional type of nitrogen doping dominates over the pyridinic configuration. In addition, X-ray diffraction (XRD) shows all the XRD peaks associated with carbon. However, the peak at ~24° is suppressed by the substrate peaks (Cu). These results suggest that nitrogen atoms can be efficiently incorporated into the graphene using thinner copper substrates, rather than the standard 25 µm ones. This is important for tailoring the properties by graphene required for microelectronic applications.
Manipulation of inherent characteristics of graphene through N and Mg atom co-doping; a DFT study

Science.gov (United States)

Rafique, Muhammad; Mirjat, Nayyar H.; Soomro, Aamir M.; Khokhar, Suhail; Shuai, Yong

2018-04-01

First-principles calculations were performed to investigate the structural, electronic, magnetic and optical properties of nitrogen (N) and magnesium (Mg) atom co-doped graphene systems. We observed that, N and Mg atom co-doping in graphene, introduces half-metallic properties in the electronic structure of graphene, introduces ferromagnetism behavior along with new trends in optical properties of graphene. Doping site and concentration of N and Mg atoms in graphene was changed and resulting effects of these changes on aforementioned properties were investigated. Through density of states plots we observed that, Mg atom sp orbitals mainly induced magnetic moments in graphene. It was revealed that, N/Mg atoms substitution in graphene introduces a red shift in absorption spectrum towards visible range and a finite absorption coefficient quantity value in 0 to 3 eV and 7 to 11 eV energy intervals is also produced, that is unavailable for absorption spectrum of intrinsic graphene. Moreover, N/Mg atoms co-doping produces increment in the reflectivity parameter of graphene in low lying energy region, while producing diminishing behavior in the higher energy range. These results offer a possibility to tune electronic, magnetic and optical characteristics of graphene sufficiently for utilization in graphene based spintronic and optoelectronic devices.
Preparation and characterization of carbon and nitrogen Co-doped TiO/sub 2/ with enhanced visible light activity

International Nuclear Information System (INIS)

Li, D.; Fang, B.; Zhang, K.; Hu, C.

2012-01-01

To make full use of solar light in photocatalysis reactions, carbon and nitrogen co-doped Titanium dioxide nanoparticles were prepared through a facile process. Subsequently the structure and properties of the doped nanoparticles were characterized by UV-Vis spectroscopy, photoluminescence spectra (PL), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. In addition, the photo-catalytic activity of the samples was evaluated by photo-catalytic degradation of methyl orange aqueous solution under visible light irradiation. Results revealed that the calcined temperatures affected the structure and photo-catalytic activity of the nanoparticles and the N, C-co-doped TiO/sub 2/ (400 deg. C) nanoparticles exhibited the highest photo-catalytic activity, which could be attributed to the synergistic effect of co-doped carbon and nitrogen atoms. (author)
Novel nitrogen-doped hierarchically porous coralloid carbon materials as host matrixes for lithium–sulfur batteries

International Nuclear Information System (INIS)

Yang, Jing; Wang, Shuyuan; Ma, Zhipeng; Du, Zhiling; Li, Chunying; Song, Jianjun; Wang, Guiling; Shao, Guangjie

2015-01-01

Highlights: • Nitrogen-doped hierarchically porous coralloid carbon/sulfur composites were prepared • Nitrogen atoms were introduced to improve electrochemical properties • The intriguing structural features benefited discharge capacity and cycling stability - Abstract: Nitrogen-doped hierarchically porous coralloid carbon/sulfur composites (N-HPCC/S) served as attractive cathode materials for lithium–sulfur (Li–S) batteries were fabricated for the first time. The nitrogen-doped hierarchically porous coralloid carbon (N-HPCC) with an appropriate nitrogen content (1.29 wt%) was synthesized via a facile hydrothermal approach, combined with subsequent carbonization–activation. The N-HPCC/S composites prepared by a simple melt–diffusion method displayed an excellent electrochemical performance. With a high sulfur content (58 wt%) in the total electrode weight, the N-HPCC/S cathode delivered a high initial discharge capacity of 1626.8 mA h g −1 and remained high up to 1086.3 mA h g −1 after 50 cycles at 100 mA g −1 , which is about 1.86 times as that of activated carbon. Particularly, the reversible discharge capacity still maintained 607.2 mA h g −1 after 200 cycles even at a higher rate of 800 mA g −1 . The enhanced electrochemical performance was attributed to the synergetic effect between the intriguing hierarchically porous coralloid structure and appropriate nitrogen doping, which could effectively trap polysulfides, alleviate the volume expansion, enhance the electronic conductivity and improve the surface interaction between the carbon matrix and polysulfides
Nitrogen-doped graphene: effect of graphite oxide precursors and nitrogen content on the electrochemical sensing properties.

Science.gov (United States)

Megawati, Monica; Chua, Chun Kiang; Sofer, Zdenek; Klímová, Kateřina; Pumera, Martin

2017-06-21

Graphene, produced via chemical methods, has been widely applied for electrochemical sensing due to its structural and electrochemical properties as well as its ease of production in large quantity. While nitrogen-doped graphenes are widely studied materials, the literature showing an effect of graphene oxide preparation methods on nitrogen quantity and chemical states as well as on defects and, in turn, on electrochemical sensing is non-existent. In this study, the properties of nitrogen-doped graphene materials, prepared via hydrothermal synthesis using graphite oxide produced by various classical methods using permanganate or chlorate oxidants Staudenmaier, Hummers, Hofmann and Brodie oxidation methods, were studied; the resulting nitrogen-doped graphene oxides were labeled as ST-GO, HU-GO, HO-GO and BR-GO, respectively. The electrochemical oxidation of biomolecules, such as ascorbic acid, uric acid, dopamine, nicotinamide adenine nucleotide and DNA free bases, was carried out using cyclic voltammetry and differential pulse voltammetry techniques. The nitrogen content in doped graphene oxides increased in the order ST-GO graphene followed this trend, as shown in the cyclic voltammograms. This is a very important finding that provides insight into the electrocatalytic effect of N-doped graphene. The nitrogen-doped graphene materials exhibited improved sensitivity over bare glassy carbon for ascorbic acid, uric acid and dopamine detection. These studies will enhance our understanding of the effects of graphite oxide precursors on the electrochemical sensing properties of nitrogen-doped graphene materials.
Hierarchically structured, nitrogen-doped carbon membranes

KAUST Repository

Wang, Hong

2017-08-03

The present invention is a structure, method of making and method of use for a novel macroscopic hierarchically structured, nitrogen-doped, nano-porous carbon membrane (HNDCMs) with asymmetric and hierarchical pore architecture that can be produced on a large-scale approach. The unique HNDCM holds great promise as components in separation and advanced carbon devices because they could offer unconventional ﬂuidic transport phenomena on the nanoscale. Overall, the invention set forth herein covers a hierarchically structured, nitrogen-doped carbon membranes and methods of making and using such a membranes.
Nitrogen-Doped Graphene for Photocatalytic Hydrogen Generation.

Science.gov (United States)

Chang, Dong Wook; Baek, Jong-Beom

2016-04-20

Photocatalytic hydrogen (H2 ) generation in a water splitting process has recently attracted tremendous interest because it allows the direct conversion of clean and unlimited solar energy into the ideal energy resource of H2 . For efficient photocatalytic H2 generation, the role of the photocatalyst is critical. With increasing demand for more efficient, sustainable, and cost-effective photocatalysts, various types of semiconductor photocatalysts have been intensively developed. In particular, on the basis of its superior catalytic and tunable electronic properties, nitrogen-doped graphene is a potential candidate for a high-performance photocatalyst. Nitrogen-doped graphene also offers additional advantages originating from its unique two-dimensional sp(2) -hybridized carbon network including a large specific surface area and exceptional charge transport properties. It has been reported that nitrogen-doped graphene can play diverse but positive functions including photo-induced charge acceptor/meditator, light absorber from UV to visible light, n-type semiconductor, and giant molecular photocatalyst. Herein, we summarize the recent progress and general aspects of nitrogen-doped graphene as a photocatalyst for photocatalytic H2 generation. In addition, challenges and future perspectives in this field are also discussed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Structure and photoluminescence of boron and nitrogen co-doped carbon nanorods

Energy Technology Data Exchange (ETDEWEB)

Wang, B.B. [College of Chemistry and Chemical Engineering, Chongqing University of Technology, 69 Hongguang Rd, Lijiatuo, Banan District, Chongqing 400054 (China); Gao, B. [College of Computer Science, Chongqing University, Chongqing 400044 (China); Chongqing Municipal Education Examinations Authority, Chongqing 401147 (China); Zhong, X.X., E-mail: xxzhong@sjtu.edu.cn [Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Shao, R.W.; Zheng, K. [Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124 (China)

2016-07-15

Graphical abstract: Boron- and nitrogen- doped carbon nanorods. - Highlights: • The co-doping of nitrogen and boron in carbon nanorods. • The doping mechanism of nitrogen and boron in carbon nanorods by plasma. • Photoluminescence properties of nitrogen- and boron-doped carbon nanorods. - Abstract: Boron and nitrogen doped carbon nanorods (BNCNRs) were synthesized by plasma-enhanced hot filament chemical vapor deposition, where methane, nitrogen and hydrogen were used as the reaction gases and boron carbide was the boron source. The results of scanning electron microscopy, micro-Raman spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy indicate that boron and nitrogen can be used as co-dopants in amorphous carbon nanorods. Combined with the characterization results, the doping mechanism was studied. The mechanism is used to explain the formation of different carbon materials by different methods. The photoluminescence (PL) properties of BNCNRs were studied. The PL results show that the BNCNRs generate strong green PL bands and weak blue PL bands, and the PL intensity lowered due to the doping of boron. The outcomes advance our knowledge on the synthesis and optical properties of carbon-based nanomaterials and contribute to the development of optoelectronic nanodevices based on nano-carbon mateirals.
High rate capability of TiO{sub 2}/nitrogen-doped graphene nanocomposite as an anode material for lithium–ion batteries

Energy Technology Data Exchange (ETDEWEB)

Cai, Dandan; Li, Dongdong; Wang, Suqing [School of Chemistry and Chemical Engineering, South China University of Technology, Wushan Road, Guangzhou (China); Zhu, Xuefeng; Yang, Weishen [State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian (China); Zhang, Shanqing [Centre for Clean Environment and Energy, Environmental Futures Centre and Griffith School of Environment, Gold Coast Campus, Griffith University, QLD 4222 (Australia); Wang, Haihui, E-mail: hhwang@scut.edu.cn [School of Chemistry and Chemical Engineering, South China University of Technology, Wushan Road, Guangzhou (China)

2013-06-05

Highlights: ► TiO{sub 2}/N-doped graphene composite was synthesized by a gas/liquid interfacial method. ► The nanocomposite was used to fabricate lithium-ion batteries. ► Its electrochemical performance was evaluated for the first time. ► The anode material exhibits a good cycling performance and rate capability. -- Abstract: TiO{sub 2}/nitrogen-doped graphene nanocomposite was synthesized by a facile gas/liquid interface reaction. The structure and morphology of the sample were analyzed by X-ray diffraction analysis, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. The results indicate that nitrogen atoms were successfully doped into graphene sheets. The TiO{sub 2} nanoparticles (8–13 nm in size) were homogenously anchored on the nitrogen-doped graphene sheets through gas/liquid interface reaction. The as-prepared TiO{sub 2}/nitrogen-doped graphene nanocomposite shows a better electrochemical performance than the TiO{sub 2}/graphene nanocomposite and the bare TiO{sub 2} nanoparticles. TiO{sub 2}/nitrogen-doped graphene nanocomposite exhibits excellent cycling stability and shows high capacity of 136 mAh g{sup −1} (at a current density of 1000 mA g{sup −1}) after 80 cycles. More importantly, a high reversible capacity of 109 mAh g{sup −1} can still be obtained even at a super high current density of 5000 mA g{sup −1}. The superior electrochemical performance is attributed to the good electronic conductivity introduced by the nitrogen-doped graphene sheets and the positive synergistic effect between nitrogen-doped graphene sheets and TiO{sub 2} nanoparticles.
Electronic structure and field emission properties of nitrogen doped graphene nano-flakes (GNFs:N) and carbon nanotubes (CNTs:N)

Energy Technology Data Exchange (ETDEWEB)

Ray, Sekhar C., E-mail: Raysc@unisa.ac.za [Department of Physics, College of Science, Engineering and Technology, University of South Africa, Private Bag X6, Florida, 1710, Science Campus, Christiaan de Wet and Pioneer Avenue, Florida Park, Johannesburg (South Africa); Pong, W.F. [Department of Physics, Tamkang University, Tamsui 251, New Taipei City, Taiwan (China); Papakonstantinou, P. [Nanotechnology and Integrated Bio-Engineering Centre, University of Ulster, Shore Road, Newtownabbey BT37 0QB (United Kingdom)

2016-09-01

Highlights: • Nitrogen doped graphene nano-flakes (GNFs:N) and carbon nano-tubes (CNTs:N) are used to study the electronic/bonding structure along with their defects state. • The I{sub D}/I{sub G} ratio obtained from Raman spectroscopy used for the study of the defects states of CNTs:N than GNFs:N. • The electron field emission result shows that the turn on electric field is lower in case of CNTs:N than GNFs:N. • All results are good agreement with XANES and the results obtained from Raman spectra. - Abstract: Substitution of hetero-atom doping is a promising route to modulate the outstanding material properties of carbon nanotubes and graphene for customized applications. Nitrogen-doping has been introduced to ensure tunable work-function, enhanced n-type carrier concentration, diminished surface energy, and manageable polarization. Along with the promising assessment of N-doping effects, research on the N-doped carbon based composite structures is emerging for the synergistic integration with various functional materials. Nitrogen undoped/doped graphene nano-flakes (GNFs/GNFs:N) and multiwall carbon nano-tubes (MWCNTs/MWCNTs:N) are used for comparative study of their electronic/bonding structure along with their defects state. X-ray absorption near edge structure (XANES) spectroscopy shows that the GNFs:N produce mainly pyridine like structure; whereas MWCNTs:N shows graphitic nitrogen atoms are attached with the carbon lattice. The I{sub D}/I{sub G} ratio obtained from Raman spectroscopy shows that the defects is higher in MWCNTs:N than GNFs:N. The electron field emission result shows that the turn on electric field is lower (higher electron emission current) in case of MWCNTs:N than GNFs:N and are good agreement with XANES and the results obtained from Raman spectra.
Nitrogen-Doped Carbon for Red Phosphorous Based Anode Materials for Lithium Ion Batteries

Directory of Open Access Journals (Sweden)

Jiaoyang Li

2018-01-01

Full Text Available Serving as conductive matrix and stress buffer, the carbon matrix plays a pivotal role in enabling red phosphorus to be a promising anode material for high capacity lithium ion batteries and sodium ion batteries. In this paper, nitrogen-doping is proved to effective enhance the interface interaction between carbon and red phosphorus. In detail, the adsorption energy between phosphorus atoms and oxygen-containing functional groups on the carbon is significantly reduced by nitrogen doping, as verified by X-ray photoelectron spectroscopy. The adsorption mechanisms are further revealed on the basis of DFT (the first density functional theory calculations. The RPNC (red phosphorus/nitrogen-doped carbon composite material shows higher cycling stability and higher capacity than that of RPC (red phosphorus/carbon composite anode. After 100 cycles, the RPNC still keeps discharge capacity of 1453 mAh g−1 at the current density of 300 mA g−1 (the discharge capacity of RPC after 100 cycles is 1348 mAh g−1. Even at 1200 mA g−1, the RPNC composite still delivers a capacity of 1178 mAh g−1. This work provides insight information about the interface interactions between composite materials, as well as new technology develops high performance phosphorus based anode materials.
Nitrogen-doped graphene prepared by a transfer doping approach for the oxygen reduction reaction application

Science.gov (United States)

Mo, Zaiyong; Zheng, Ruiping; Peng, Hongliang; Liang, Huagen; Liao, Shijun

2014-01-01

Well defined nitrogen-doped graphene (NG) is prepared by a transfer doping approach, in which the graphene oxide (GO) is deoxidized and nitrogen doped by the vaporized polyaniline, and the GO is prepared by a thermal expansion method from graphite oxide. The content of doped nitrogen in the doped graphene is high up to 6.25 at% by the results of elements analysis, and oxygen content is lowered to 5.17 at%. As a non-precious metal cathode electrocatalyst, the NG catalyst exhibits excellent activity toward the oxygen reduction reaction, as well as excellent tolerance toward methanol. In 0.1 M KOH solution, its onset potential, half-wave potential and limiting current density for the oxygen reduction reaction reach 0.98 V (vs. RHE), 0.87 V (vs. RHE) and 5.38 mA cm-2, respectively, which are comparable to those of commercial 20 wt% Pt/C catalyst. The well defined graphene structure of the catalyst is revealed clearly by HRTEM and Raman spectra. It is suggested that the nitrogen-doping and large surface area of the NG sheets give the main contribution to the high ORR catalytic activity.

First-principles study on silicon atom doped monolayer graphene

Science.gov (United States)

Rafique, Muhammad; Shuai, Yong; Hussain, Nayyar

2018-01-01

This paper illustrates the structural, electronic and optical properties of individual silicon (Si) atom-doped single layer graphene using density functional theory method. Si atom forms tight bonding with graphene layer. The effect of doping has been investigated by varying the concentration of Si atoms from 3.125% to 9.37% (i.e. From one to three Si atoms in 4 × 4 pure graphene supercell containing 32 carbon atoms), respectively. Electronic structure, partial density of states (PDOS) and optical properties of pure and Si atom-doped graphene sheet were calculated using VASP (Vienna ab-initio Simulation Package). The calculated results for pure graphene sheet were then compared with Si atom doped graphene. It is revealed that upon Si doping in graphene, a finite band gap appears at the high symmetric K-point, thereby making graphene a direct band gap semiconductor. Moreover, the band gap value is directly proportional to the concentration of impurity Si atoms present in graphene lattice. Upon analyzing the optical properties of Si atom-doped graphene structures, it is found that, there is significant change in the refractive index of the graphene after Si atom substitution in graphene. In addition, the overall absorption spectrum of graphene is decreased after Si atom doping. Although a significant red shift in absorption is found to occur towards visible range of radiation when Si atom is substituted in its lattice. The reflectivity of graphene improves in low energy region after Si atom substitution in graphene. These results can be useful for tuning the electronic structure and to manipulate the optical properties of graphene layer in the visible region.
Simple method of preparing nitrogen - doped nanosized TiO2 powders of high photocatalytic activity under visible light

International Nuclear Information System (INIS)

Nguyen Van Hung; Dang Thi Thanh Le

2014-01-01

Nitrogen-doped nanosized TiO 2 powders were prepared by a simple thermal treatment method of the mixture of titanium dioxide and urea. The prepared products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectra (UV-Vis-DRS) and Fourier transform infrared (FT-IR) spectroscopy. The results showed that the crystal structure of N-TiO 2 was a mixture of anatase and rutile phases, and the average particle size was 31 nm calculated from XRD results. The UV-vis spectra indicate an increase in absorption of visible light when compared to undoped TiO 2 . The photocatalytic activity of nitrogen-doped TiO 2 powder was evaluated by the decomposition of methylene blue under visible light irradiation. And it was found that nitrogen-doped TiO 2 powders exhibited much higher photocatalytic activity than undoped TiO 2 . Moreover, the study also showed that, the doping N atoms improve the growth of the TiO 2 crystal and phase transformation. (author)
Recognizing nitrogen dopant atoms in graphene using atomic force microscopy

DEFF Research Database (Denmark)

van der Heijden, Nadine J.; Smith, Daniel; Calogero, Gaetano

2016-01-01

Doping graphene by heteroatoms such as nitrogen presents an attractive route to control the position of the Fermi level in the material. We prepared N-doped graphene on Cu(111) and Ir(111) surfaces via chemical vapor deposition of two different molecules. Using scanning tunneling microscopy image...
Giant tunnel-electron injection in nitrogen-doped graphene

DEFF Research Database (Denmark)

Lagoute, Jerome; Joucken, Frederic; Repain, Vincent

2015-01-01

Scanning tunneling microscopy experiments have been performed to measure the local electron injection in nitrogen-doped graphene on SiC(000) and were successfully compared to ab initio calculations. In graphene, a gaplike feature is measured around the Fermi level due to a phonon-mediated tunneling...... and at carbon sites. Nitrogen doping can therefore be proposed as a way to improve tunnel-electron injection in graphene....
Nitrogen-doped Sb-rich Si–Sb–Te phase-change material for high-performance phase-change memory

International Nuclear Information System (INIS)

Zhou, Xilin; Wu, Liangcai; Song, Zhitang; Cheng, Yan; Rao, Feng; Ren, Kun; Song, Sannian; Liu, Bo; Feng, Songlin

2013-01-01

The effects of nitrogen doping on the phase-change performance of Sb-rich Si–Sb–Te materials are systemically investigated, focusing on the chemical state and the role of nitrogen upon crystallization. The tendency of N atoms to bond with Si (SiN x ) in the crystalline film is analyzed by X-ray photoelectron spectroscopy. The microstructures of the materials mixed with Sb 2 Te crystal grains and amorphous Si/SiN x regions are elucidated via in situ transmission electron microscopy, from which a percolation behavior is demonstrated to possibly describe the random crystallization feature in the nucleation-dominated nanocomposite material. The phase-change memory cells based on N-doped Sb-rich Si–Sb–Te materials display more stable and reliable electrical performance than the nitrogen-free ones. An endurance characteristic in the magnitude of 10 7 cycles of the phase-change memory cells is realized with moderate nitrogen addition, meaning that the nitrogen incorporation into Si–Sb–Te material is a suitable method to achieve high-performance phase-change memory for commercial applications
Preparation of nitrogen-doped titania using sol-gel technique and its photocatalytic activity

International Nuclear Information System (INIS)

Qin Haoli; Gu Guobang; Liu Song

2008-01-01

Yellowish nitrogen-doped titania was produced through sol-gel method at room temperature, with the elemental nitrogen derived from aqua ammonia. The titania catalysts were characterized using TG-DSC, XRD, BET, TEM, and UV-vis diffuse reflectance spectrophotometer. Methyl orange (MO) and 2-mercaptobenzothiazole (MBT) were used in this study as model chemicals and both the adsorption isotherm and photocatalytic activity of the nitrogen-doped titania catalysts were evaluated based on the MO and MBT photodegradation in aqueous solution under UV and visible light, respectively. The results showed that all titania catalysts were anatase. The crystallite size of nitrogen-doped ones increased with the increase of N/Ti proportion, both the adsorption capacity and adsorption equilibrium constants of the nitrogen-doped titania catalysts were improved by the doping of nitrogen. The doping of nitrogen could extend the absorption shoulder into the visible-light region, thus nitrogen-doped titania possessed visible-light activity illustrated by that higher capability of degradation of MO and MBT under the irradiation of visible light, whereas the pure ones showed little such kind of visible-light activity. The kinetics of the MO and MBT photodegradation using different nitrogen-doped titania were also studied, the experiments demonstrated that there was an optimum N/Ti proportion of 4 mol% to exhibit the highest visible-light activity. The UV activity of nitrogen-doped titania catalysts were worse than that of the pure one and Degussa P-25. In addition, nitrogen-doped titania had weakened appreciably activity in the visible-light region as the N/Ti proportion increased, while a reverse relationship exists for the UV light. It was concluded that the enhancement of MO and MBT photodegradation using the nitrogen-doped titania catalysts mainly involved in both the improvement of the organic substrate adsorption in catalysts suspension and the enhancement of the separation of electron
Effect of nitrogen doping on titanium carbonitride-derived adsorbents used for arsenic removal

Energy Technology Data Exchange (ETDEWEB)

Han, Jisun [Department of Materials Science and Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of); Lee, Soonjae [Center for Water Resource Cycle Research, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Choi, Keunsu [Computational Science Research Center, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Kim, Jinhong [Samsung Electronics Co.Ltd.,(Maetan dong) 129, Samsung-ro Yeongtong-gu, Suwonsi, Gyeonggi-do 443-742, Repubilc of Korea (Korea, Republic of); Ha, Daegwon [Department of Materials Science and Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of); Lee, Chang-Gu [Center for Water Resource Cycle Research, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); An, Byungryul [Department of Civil Engineering, Sangmyung University, Cheonan, Chungnam 31066 (Korea, Republic of); Lee, Sang-Hyup [Center for Water Resource Cycle Research, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Mizuseki, Hiroshi, E-mail: mizuseki@kist.re.kr [Computational Science Research Center, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Choi, Jae-Woo, E-mail: plead36@kist.re.kr [Center for Water Resource Cycle Research, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Department of Energy and Environmental Engineering, University of Science and Technology (UST), Daejeon 305-350 (Korea, Republic of); Kang, Shinhoo, E-mail: shinkang@snu.ac.kr [Department of Materials Science and Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)

2016-01-25

Highlights: • The N-doping can improve the As adsorption performance of carbon-based materials. • The material features high micro- and small meso-pores with exceptional surface area. • Pyrrolic N atoms distributed uniformly on the micropores act as adsorption sites. • The synthesis temperature affected pore properties and surface functional groups. - Abstract: Arsenic in water and wastewater is considered to be a critical contaminant as it poses harmful health risks. In this regard, to meet the stringent regulation of arsenic in aqueous solutions, nitrogen doped carbon-based materials (CN) were prepared as adsorbents and tested for the removal of arsenic ion from aqueous solutions. Nitrogen-doped carbon (CNs) synthesized by chlorination exhibited well-developed micro- and small meso-pores with uniform pore structures. The structure and characteristics of the adsorbents thus developed were confirmed by field-emission scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. Among the CNs developed, CN700 exhibited high adsorption capacity for arsenic (31.08 mg/g). The adsorption efficiency for arsenic ion was confirmed to be affected by pyrrolic nitrogen and micro-pores. These results suggest that CNs are useful adsorbents for the treatment of arsenic, and in particular, CN700 demonstrates potential for application as an adsorbent for the removal of anionic heavy metals from wastewater and sewage.
Effect of nitrogen doping of graphene oxide on hydrogen and hydroxyl adsorption

Energy Technology Data Exchange (ETDEWEB)

Min, Byeong June; Jeong, Hae Kyung [Daegu University, Kyungsan (Korea, Republic of)

2014-05-15

We investigate how nitrogen-doping affects the hydrogen (H) and the hydroxyl (OH) adsorption on graphene oxide (GO) and on nitrogen-doped GO (NGO) via pseudopotential plane wave density functional calculations within the local spin density approximation. We find that the nitrogen doping brings about drastic changes in the hydrogen and the hydroxyl adsorption energetics, but its effects depend sensitively on the nitrogen configuration in NGO. The H and the OH adsorption energies are comparable only for pyrrolic NGO. In GO and quarternary NGO, the H adsorption energy is greater than the OH adsorption energy while the trend is reversed in pyridinic NGO. Also, the OH adsorption process is less affected by nitrogen-doping than the H adsorption is.
Supercapacitors based on nitrogen-doped reduced graphene oxide and borocarbonitrides

Science.gov (United States)

Gopalakrishnan, K.; Moses, Kota; Govindaraj, A.; Rao, C. N. R.

2013-12-01

Nitrogen-doped reduced graphene oxide (RGO) samples with different nitrogen content, prepared by two different methods, as well as nitrogen-doped few-layer graphene have been investigated as supercapacitor electrodes. Two electrode measurements have been carried out both in aqueous (6M KOH) and in ionic liquid media. Nitrogen-doped reduced graphene oxides exhibit satisfactory specific capacitance, the values reaching 126F/g at a scan rate of 10mV/s in aqueous medium. Besides providing supercapacitor characteristics, the study has shown the nitrogen content and surface area to be important factors. High surface-area borocarbonitrides, BxCyNz, prepared by the urea route appear to be excellent supercapacitor electrode materials. Thus, BC4.5N exhibits a specific capacitance of 169F/g at a scan rate of 10mV/s in aqueous medium. In an ionic liquid medium, nitrogen-doped RGO and BC4.5N exhibit specific capacitance values of 258F/g and 240F/g at a scan rate of 5mV/s. The ionic liquid enables a larger operating voltage range of 0.0-2.5V compared to 0.0-1V in aqueous medium.
Molecular rectification modulated by alternating boron and nitrogen co-doping in a combined heterostructure of two zigzag-edged trigonal graphenes

International Nuclear Information System (INIS)

Wang, Li-hua; Sun, Yan; Zhang, Zi-zhen; Ding, Bing-jun; Guo, Yong

2014-01-01

The rectifying properties of a heterostructure combined with two trigonal graphenes are investigated by first-principles approach. The graphenes have left (left and right) vertical benzenes substituted with alternating nitrogen and boron atoms. The results indicate that co-doping atoms have distinct influences on the rectifying performance of such devices. When the left trigonal graphene is doped and two trigonal graphenes are bound through a BH pair, a reverse rectifying behavior can be observed. However, a forward rectifying behavior is observed when they are bound through an NH (NB) pair. The rectifying effect is more prominent for the NB pair.
Nitrogen-Doped Carbon Dots as A New Substrate for Sensitive Glucose Determination

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Hanxu Ji

2016-05-01

Full Text Available Nitrogen-doped carbon dots are introduced as a novel substrate suitable for enzyme immobilization in electrochemical detection metods. Nitrogen-doped carbon dots are easily synthesised from polyacrylamide in just one step. With the help of the amino group on chitosan, glucose oxidase is immobilized on nitrogen-doped carbon dots-modified carbon glassy electrodes by amino-carboxyl reactions. The nitrogen-induced charge delocalization at nitrogen-doped carbon dots can enhance the electrocatalytic activity toward the reduction of O2. The specific amino-carboxyl reaction provides strong and stable immobilization of GOx on electrodes. The developed biosensor responds efficiently to the presence of glucose in serum samples over the concentration range from 1 to 12 mM with a detection limit of 0.25 mM. This novel biosensor has good reproducibility and stability, and is highly selective for glucose determination under physiological conditions. These results indicate that N-doped quantum dots represent a novel candidate material for the construction of electrochemical biosensors.
Microwave plasma-assisted photoluminescence enhancement in nitrogen-doped ultrananocrystalline diamond film

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Yu Lin Liu

2012-06-01

Full Text Available Optical properties and conductivity of nitrogen-doped ultrananocrystal diamond (UNCD films were investigated following treatment with low energy microwave plasma at room temperature. The plasma also generated vacancies in UNCD films and provided heat for mobilizing the vacancies to combine with the impurities, which formed the nitrogen-vacancy defect centers. The generated color centers were distributed uniformly in the samples. The conductivity of nitrogen-doped UNCD films treated by microwave plasma was found to decrease slightly due to the reduced grain boundaries. The photoluminescence emitted by the plasma treated nitrogen-doped UNCD films was enhanced significantly compared to the untreated films.
Study of Nitrogen Effect on the Boron Diffusion during Heat Treatment in Polycrystalline Silicon/Nitrogen-Doped Silicon Thin Films

Science.gov (United States)

Saci, Lynda; Mahamdi, Ramdane; Mansour, Farida; Boucher, Jonathan; Collet, Maéva; Bedel Pereira, Eléna; Temple-Boyer, Pierre

2011-05-01

The present paper studies the boron (B) diffusion in nitrogen (N) doped amorphous silicon (a-Si) layer in original bi-layer B-doped polycrystalline silicon (poly-Si)/in-situ N-doped Si layers (NIDOS) thin films deposited by low pressure chemical vapor deposition (LPCVD) technique. The B diffusion in the NIDOS layer was investigated by secondary ion mass spectrometry (SIMS) and Fourier transform infrared spectroscopy (FTIR) analysis. A new extended diffusion model is proposed to fit the SIMS profile of the bi-layer films. This model introduces new terms which take into account the effect of N concentration on the complex diffusion phenomena of B atoms in bi-layer films. SIMS results show that B diffusion does not exceed one third of NIDOS layer thickness after annealing. The reduction of the B diffusion in the NIDOS layer is due to the formation of complex B-N as shown by infrared absorption measurements. Electrical measurements using four-probe and Hall effect techniques show the good conductivity of the B-doped poly-Si layer after annealing treatment.
A Nanopore-Structured Nitrogen-Doped Biocarbon Electrocatalyst for Oxygen Reduction from Two-Step Carbonization of Lemna minor Biomass

Science.gov (United States)

Guo, Chaozhong; Li, Zhongbin; Niu, Lidan; Liao, Wenli; Sun, Lingtao; Wen, Bixia; Nie, Yunqing; Cheng, Jing; Chen, Changguo

2016-05-01

So far, the development of highly active and stable carbon-based electrocatalysts for oxygen reduction reaction (ORR) to replace commercial Pt/C catalyst is a hot topic. In this study, a new nanoporous nitrogen-doped carbon material was facilely designed by two-step pyrolysis of the renewable Lemna minor enriched in crude protein under a nitrogen atmosphere. Electrochemical measurements show that the onset potential for ORR on this carbon material is around 0.93 V (versus reversible hydrogen electrode), slightly lower than that on the Pt/C catalyst, but its cycling stability is higher compared to the Pt/C catalyst in an alkaline medium. Besides, the ORR at this catalyst approaches to a four-electron transfer pathway. The obtained ORR performance can be basically attributed to the formation of high contents of pyridinic and graphitic nitrogen atoms inside this catalyst. Thus, this work opens up the path in the ORR catalysis for the design of nitrogen-doped carbon materials utilizing aquatic plants as starting precursors.
Preparation and Photocatalytic Activity of Nitrogen-doped Nano TiO2/Tourmaline Composites

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LIU Xin-wei

2016-06-01

Full Text Available Using Ti(OC4H94 as precursor, CO(NH22 as nitrogen source, tourmaline as support, the nitrogen-doped nano TiO2/tourmaline composites were synthesized by sol-gel method with ultrasound assisted.The structure and performance of composites were characterized by XRD, FT-IR, UV-Vis DRS, SEM, EDS.The effects of calcining temperature, nitrogen-doped content, tourmaline amount, catalyst system on the photocatalytic activity of nitrogen-doped nano TiO2/tourmaline composites were studied.The results show that the photocatalytic activity of nitrogen-doped nano TiO2/tourmaline composites calcined under 500℃, the nitrogen doped amount of 5% (mole fraction, tourmaline added in an amount of 10% (mass fraction, catalyst dosage of 3g/L, under 500W UV light irradiation conditions, the photocatalytic degradation effect of TNT(10mg/L is the best, and has a good recycling performance.
Investigation of corrosion behavior of nitrogen doped and platinum/ruthenium doped diamond-like carbon thin films in Hank's solution

International Nuclear Information System (INIS)

Khun, N.W.; Liu, E.

2011-01-01

Undoped (DLC), nitrogen-doped (N-DLC) and platinum/ruthenium doped diamond-like carbon (PtRu-DLC) thin films were deposited on p-Si (100) substrates using a DC magnetron sputtering deposition system. The chemical composition, bonding structure, surface morphology and adhesion strength of the films were characterized using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM) and micro-scratch test, respectively. The corrosion behavior of the films in a Hank's solution was investigated using potentiodynamic polarization test. The corrosion results revealed that the PtRu-DLC film had the highest corrosion potential among the films used in this study. Highlights: → DLC thin films were deposited on Si substrates via dc magnetron sputtering. → Some DLC films were doped with N and/or Pt/Ru. → The film corrosion behavior was studied in a Hank solution with polarization test. → The PtRu-DLC film showed the highest corrosion potential among the films studied.
Nitrogen-Doped Graphene/Platinum Counter Electrodes for Dye-Sensitized Solar Cells

KAUST Repository

Lin, Chinan; Lee, Chuanpei; Ho, Shute; Wei, Tzuchiao; Chi, Yuwen; Huang, Kunping; He, Jr-Hau

2014-01-01

Nitrogen-doped graphene (NGR) was utilized in dye-sensitized solar cells for energy harvesting. NGR on a Pt-sputtered fluorine-doped tin oxide substrate (NGR/Pt/FTO) as counter electrodes (CEs) achieves the high efficiency of 9.38% via the nitrogen
Evaluation of the Aromaticity of a Non-Planar Carbon Nano-Structure by Nucleus-Independent Chemical Shift Criterion: Aromaticity of the Nitrogen- Doped Corannulene

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A. Reisi-Vanani

2014-04-01

Full Text Available Substitution of two or four carbon atoms by nitrogen in the corannulene molecule as a carbon nanostructure was done and the obtained structures were optimized at MP2/6-31G(d level of theory. Calculations of the nucleus-independent chemical shift (NICS were performed to analyze the aromaticity of the corannulene rings and its derivatives upon doping with N at B3LYP/6-31G(d level of theory. Results showed NICS values in six-membered and five-membered rings of two and four N atoms doped corannulene are different and very dependent to number and position of the N atoms. The values of the mean NICS of all N-doped structures are more positive than intact corannulene that show insertion of N atom to the structures causes to decreasing aromaticity of them.
Nitrogen-Doped Graphene/Platinum Counter Electrodes for Dye-Sensitized Solar Cells

KAUST Repository

Lin, Chinan

2014-12-17

Nitrogen-doped graphene (NGR) was utilized in dye-sensitized solar cells for energy harvesting. NGR on a Pt-sputtered fluorine-doped tin oxide substrate (NGR/Pt/FTO) as counter electrodes (CEs) achieves the high efficiency of 9.38% via the nitrogen doping into graphene. This is due to (i) the hole-cascading transport at the interface of electrolyte/CEs via controlling the valence band maximum of NGR located between the redox potential of the I-/I- redox couple and the Fermi level of Pt by nitrogen doping, (ii) the extended electron transfer surface effect provided by large-surface-area NGR, (iii) the high charge transfer efficiency due to superior catalytic characteristics of NGR via nitrogen doping, and (iv) the superior light-reflection effect of NGR/Pt/FTO CEs, facilitating the electron transfer from CEs to I3 - ions of the electrolyte and light absorption of dye. The result demonstrated that the NGR/Pt hybrid structure is promising in the catalysis field. (Chemical Presented). © 2014 American Chemical Society.
XPS studies of nitrogen doping niobium used for accelerator applications

Science.gov (United States)

Yang, Ziqin; Lu, Xiangyang; Tan, Weiwei; Zhao, Jifei; Yang, Deyu; Yang, Yujia; He, Yuan; Zhou, Kui

2018-05-01

Nitrogen doping study on niobium (Nb) samples used for the fabrication of superconducting radio frequency (SRF) cavities was carried out. The samples' surface treatment was attempted to replicate that of the Nb SRF cavities, which includes heavy electropolishing (EP), nitrogen doping and the subsequent EP with different amounts of material removal. The surface chemical composition of Nb samples with different post treatments has been studied by XPS. The chemical composition of Nb, O, C and N was presented before and after Gas Cluster Ion Beam (GCIB) etching. No signals of poorly superconducting nitrides NbNx was found on the surface of any doped Nb sample with the 2/6 recipe before GCIB etching. However, in the depth range greater than 30 nm, the content of N element is below the XPS detection precision scope even for the Nb sample directly after nitrogen doping treatment with the 2/6 recipe.

Conductivity study of nitrogen-doped calcium zinc oxide prepared by spray pyrolysis

International Nuclear Information System (INIS)

Hsu, Yu-Ting; Lan, Wen-How; Huang, Kai-Feng; Lin, Jia-Ching; Chang, Kuo-Jen

2016-01-01

In this study, the spray pyrolysis method was used to prepare unintentionally doped and nitrogen-doped calcium zinc oxide films by using zinc acetate, calcium nitrate precursor, and ammonium acetate precursor. Morphological and structural analyses were conducted using scanning electron microscopy and X-ray diffraction. The results indicated that film grain size decreased as the nitrogen doping was increased. Both calcium oxide and zinc oxide structures were identified in the unintentionally doped calcium zinc oxide. When nitrogen doping was introduced, the film mainly exhibited a zinc oxide structure with preferred (002) and (101) orientations. The concentration and mobility were investigated using a Hall measurement system. P-type films with a mobility and concentration of 10.6 cm"2 V"−"1 s"−"1 and 2.8×10"1"7 cm"−"3, respectively, were obtained. Moreover, according to a temperature-dependent conductivity analysis, an acceptor state with activation energy 0.266 eV dominated the p-type conduction for the unintentionally doped calcium zinc oxide. By contrast, a grain boundary with a barrier height of 0.274–0.292 eV dominated the hole conduction for the nitrogen-doped calcium zinc oxide films.
Visible-light driven nitrogen-doped petal-morphological ceria nanosheets for water splitting

Science.gov (United States)

Qian, Junchao; Zhang, Wenya; Wang, Yaping; Chen, Zhigang; Chen, Feng; Liu, Chengbao; Lu, Xiaowang; Li, Ping; Wang, Kaiyuan; Chen, Ailian

2018-06-01

Water splitting is a promising sustainable technology for solar-to-chemical energy conversion. Herein, we successfully fabricated nitrogen-doped ultrathin CeO2 nanosheets by using field poppy petals as templates, which exhibit an efficiently catalytic activity for water splitting. Abundant oxygen vacancies and substitutional N atoms were experimentally observed in the film due to its unique biomorphic texture. In view of high efficiency and long durability of the as-prepared photocatalyst, this biotemplate method may provide an alternative technique for using biomolecules to assemble 2D nanomaterials.
Doping monolayer graphene with single atom substitutions

KAUST Repository

Wang, Hongtao

2012-01-11

Functionalized graphene has been extensively studied with the aim of tailoring properties for gas sensors, superconductors, supercapacitors, nanoelectronics, and spintronics. A bottleneck is the capability to control the carrier type and density by doping. We demonstrate that a two-step process is an efficient way to dope graphene: create vacancies by high-energy atom/ion bombardment and fill these vacancies with desired dopants. Different elements (Pt, Co, and In) have been successfully doped in the single-atom form. The high binding energy of the metal-vacancy complex ensures its stability and is consistent with in situ observation by an aberration-corrected and monochromated transmission electron microscope. © 2011 American Chemical Society.
Hierarchically structured, nitrogen-doped carbon membranes

KAUST Repository

Wang, Hong; Wu, Tao

2017-01-01

The present invention is a structure, method of making and method of use for a novel macroscopic hierarchically structured, nitrogen-doped, nano-porous carbon membrane (HNDCMs) with asymmetric and hierarchical pore architecture that can be produced
Clean Nanotube Unzipping by Abrupt Thermal Expansion of Molecular Nitrogen: Graphene Nanoribbons with Atomically Smooth Edges

Energy Technology Data Exchange (ETDEWEB)

Sumpter, Bobby G [ORNL; Meunier, Vincent [ORNL; Terrones, M. [Universidad Carlos III, Madrid, Spain; Endo, M [Shinshu University; Munoz-Sandoval, Emilio [IPICyT; Kim, Y A [Shinshu University; Morelos-Bomez, Aaron [Shinshu University; Vega-Diaz, Sofia [Shinshu University

2012-01-01

We report a novel physicochemical route to produce highly crystalline nitrogen-doped graphene nanoribbons. The technique consists of an abrupt N2 gas expansion within the hollow core of nitrogen-doped multiwalled carbon nanotubes (CNx-MWNTs) when exposed to a fast thermal shock. The multiwalled nanotube unzipping mechanism is rationalized using molecular dynamics and density functional theory simulations, which highlight the importance of open-ended nanotubes in promoting the efficient introduction of N2 molecules by capillary action within tubes and surface defects, thus triggering an efficient and atomically smooth unzipping. The so-produced nanoribbons could be few-layered (from graphene bilayer onward) and could exhibit both crystalline zigzag and armchair edges. In contrast to methods developed previously, our technique presents various advantages: (1) the tubes are not heavily oxidized; (2) the method yields sharp atomic edges within the resulting nanoribbons; (3) the technique could be scaled up for the bulk production of crystalline nanoribbons from available MWNT sources; and (4) this route could eventually be used to unzip other types of carbon nanotubes or intercalated layered materials such as BN, MoS2, WS2, etc.
Eco-Friendly Synthesis of Nitrogen-Doped Mesoporous Carbon for Supercapacitor Application

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Georges Moussa

2018-03-01

Full Text Available A sustainable and simple synthesis procedure involving the co-assembly of green phenolic resin and amphiphilic polymer template in water/ethanol mixture at room temperature to synthesize nitrogen doped mesoporous carbon is reported herein. Guanine is proposed as a novel nitrogen-based precursor which is able to create H-bondings both with the phenolic resin and the template allowing the formation of mesoporous carbons with nitrogen atoms uniformly distributed in their framework. The influence of the synthesis procedure, template amount and annealing temperature on the carbon textural properties, structure and surface chemistry were investigated. For several conditions, carbon materials with ordered pore size and high nitrogen content (up to 10.6 at % could be achieved. The phase separation procedure combined with optimal amount of template favor the formation of ordered mesoporous carbons with higher specific surface area while the increase in the temperature induces a decrease in the surface area and amount of heteroatoms (N and O. The electrochemical performances as electrode in supercapacitors were evaluated in acidic medium and the capacitance was closely related to the material conductivity and surface chemistry.
Nitrogen-Doped Carbon Nanotube and Graphene Materials for Oxygen Reduction Reactions

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Qiliang Wei

2015-09-01

Full Text Available Nitrogen-doped carbon materials, including nitrogen-doped carbon nanotubes (NCNTs and nitrogen-doped graphene (NG, have attracted increasing attention for oxygen reduction reaction (ORR in metal-air batteries and fuel cell applications, due to their optimal properties including excellent electronic conductivity, 4e− transfer and superb mechanical properties. Here, the recent progress of NCNTs- and NG-based catalysts for ORR is reviewed. Firstly, the general preparation routes of these two N-doped carbon-allotropes are introduced briefly, and then a special emphasis is placed on the developments of both NCNTs and NG as promising metal-free catalysts and/or catalyst support materials for ORR. All these efficient ORR electrocatalysts feature a low cost, high durability and excellent performance, and are thus the key factors in accelerating the widespread commercialization of metal-air battery and fuel cell technologies.
A facile approach towards increasing the nitrogen-content in nitrogen-doped carbon nanotubes via halogenated catalysts

International Nuclear Information System (INIS)

Ombaka, L.M.; Ndungu, P.G.; Omondi, B.; McGettrick, J.D.; Davies, M.L.; Nyamori, V.O.

2016-01-01

Nitrogen-doped carbon nanotubes (N-CNTs) have been synthesized at 850 °C via a CVD deposition technique by use of three ferrocenyl derivative catalysts, i.e. para-CN, -CF_3 and -Cl substituted-phenyl rings. The synthesized catalysts have been characterized by NMR, IR, HR-MS and XRD. The XRD analysis of the para-CF_3 catalyst indicates that steric factors influence the X-ray structure of 1,1′-ferrocenylphenyldiacrylonitriles. Acetonitrile or pyridine was used as carbon and nitrogen sources to yield mixtures of N-CNTs and carbon spheres (CS). The N-CNTs obtained from the para-CF_3 catalysts, in pyridine, have the highest nitrogen-doping level, show a helical morphology and are less thermally stable compared with those synthesized by use of the para-CN and -Cl as catalyst. This suggests that fluorine heteroatoms enhance nitrogen-doping in N-CNTs and formation of helical-N-CNTs (H-N-CNTs). The para-CF_3 and para-Cl catalysts in acetonitrile yielded iron-filled N-CNTs, indicating that halogens promote encapsulation of iron into the cavity of N-CNT. The use of acetonitrile, as carbon and nitrogen source, with the para-CN and -Cl as catalysts also yielded a mixture of N-CNTs and carbon nanofibres (CNFs), with less abundance of CNFs in the products obtained using para-Cl catalysts. However, para-CF_3 catalyst in acetonitrile gave N-CNTs as the only shaped carbon nanomaterials. - Graphical abstract: Graphical abstract showing the synthesis of N-CNTs using halogenated-ferrocenyl derivatives as catalyst with pyridine or acetonitrile as nitrogen and carbon sources via the chemical vapour deposition technique. - Highlights: • N-CNTs were synthesized from halogenated ferrocenyl catalysts. • Halogenated catalysts promote nitrogen-doping and pyridinic nitrogen in N-CNTs. • Halogenated catalysts facilitate iron filling of N-CNTs.
Nitrogen-doped graphene films from simple photochemical doping for n-type field-effect transistors

Energy Technology Data Exchange (ETDEWEB)

Li, Xinyu [College of Science, Guilin University of Technology, Guilin 541004 (China); Department of Physics and Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093 (China); Tang, Tao; Li, Ming, E-mail: liming928@163.com, E-mail: lixinyu5260@163.com [College of Science, Guilin University of Technology, Guilin 541004 (China); He, Xiancong, E-mail: liming928@163.com, E-mail: lixinyu5260@163.com [School of Materials Science and Engineering, Nanjing Institute of Technology, Nanjing 211167 (China)

2015-01-05

Highly nitrogen-doped GO (NGO) and n-type graphene field effect transistor (FET) have been achieved by simple irradiation of graphene oxide (GO) thin films in NH{sub 3} atmosphere. The electrical properties of the NGO film were performed on electric field effect measurements, and it displays an n-type FET behavior with a charge neutral point (Dirac point) located at around −8 V. It is suggested that the amino-like nitrogen (N-A) mainly contributes to the n-type behavior. Furthermore, compared to the GO film irradiated in Ar atmosphere, the NGO film is much more capable to improve the electrical conductivity. It may attribute to nitrogen doping and oxygen reduction, both of which can effectively enhance the electrical conductivity.
Biomass derived porous nitrogen doped carbon for electrochemical devices

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Litao Yan

2017-04-01

Full Text Available Biomass derived porous nanostructured nitrogen doped carbon (PNC has been extensively investigated as the electrode material for electrochemical catalytic reactions and rechargeable batteries. Biomass with and without containing nitrogen could be designed and optimized to prepare PNC via hydrothermal carbonization, pyrolysis, and other methods. The presence of nitrogen in carbon can provide more active sites for ion absorption, improve the electronic conductivity, increase the bonding between carbon and sulfur, and enhance the electrochemical catalytic reaction. The synthetic methods of natural biomass derived PNC, heteroatomic co- or tri-doping into biomass derived carbon and the application of biomass derived PNC in rechargeable Li/Na batteries, high energy density LiâS batteries, supercapacitors, metal-air batteries and electrochemical catalytic reaction (oxygen reduction and evolution reactions, hydrogen evolution reaction are summarized and discussed in this review. Biomass derived PNCs deliver high performance electrochemical storage properties for rechargeable batteries/supercapacitors and superior electrochemical catalytic performance toward hydrogen evolution, oxygen reduction and evolution, as promising electrodes for electrochemical devices including battery technologies, fuel cell and electrolyzer. Keywords: Biomass, Nitrogen doped carbon, Batteries, Fuel cell, Electrolyzer
Investigation of corrosion behavior of nitrogen doped and platinum/ruthenium doped diamond-like carbon thin films in Hank's solution

Energy Technology Data Exchange (ETDEWEB)

Khun, N.W.; Liu, E., E-mail: MEJLiu@ntu.edu.sg

2011-10-10

Undoped (DLC), nitrogen-doped (N-DLC) and platinum/ruthenium doped diamond-like carbon (PtRu-DLC) thin films were deposited on p-Si (100) substrates using a DC magnetron sputtering deposition system. The chemical composition, bonding structure, surface morphology and adhesion strength of the films were characterized using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM) and micro-scratch test, respectively. The corrosion behavior of the films in a Hank's solution was investigated using potentiodynamic polarization test. The corrosion results revealed that the PtRu-DLC film had the highest corrosion potential among the films used in this study. Highlights: {yields} DLC thin films were deposited on Si substrates via dc magnetron sputtering. {yields} Some DLC films were doped with N and/or Pt/Ru. {yields} The film corrosion behavior was studied in a Hank solution with polarization test. {yields} The PtRu-DLC film showed the highest corrosion potential among the films studied.
Nitrogen doping on NiO by reactive magnetron sputtering: A new pathway to dynamically tune the optical and electrical properties

Energy Technology Data Exchange (ETDEWEB)

Keraudy, Julien, E-mail: julien.keraudy@liu.se [Institut de Recherche Technologique (IRT), Chemin du Chaffault, 44340, Bouguenais (France); Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, CNRS, 2 rue de la Houssinière, BP32229, 44322, Nantes Cedex 3 (France); Plasma & Coatings Physics Division, IFM Materials Physics, Linköping University, Linköping, SE 581-83 (Sweden); Ferrec, Axel; Richard-Plouet, Mireille; Hamon, Jonathan; Goullet, Antoine; Jouan, Pierre-Yves [Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, CNRS, 2 rue de la Houssinière, BP32229, 44322, Nantes Cedex 3 (France)

2017-07-01

Highlights: • Nitrogen doping into NiO lattice (4 at.%) is achieved by only monitoring the N{sub 2}/O{sub 2} gas ratio in the plasma. • The replacement of O by N leads to a narrowing of the optical band-gap energy from 3.6 to 2.3 eV. • The origin of the narrowing is explained by the presence of an intermediate band and the introduction of occupied N 2p states. • Electrical conductivity of NiO:N samples depends on the amount of nickel vacancies and the nitrogen doping. - Abstract: N-doped nickel oxide (NiO:N) thin films were deposited on glass and silicon substrates by reactive DC magnetron sputtering in Ar/O{sub 2}/N{sub 2} gas atmosphere with a series of N{sub 2}/O{sub 2} gas ratio ranging from 0 to 80%. X-ray diffraction measurements have revealed that the films are constituted of Ni{sub 1-x}O grains and showed enhanced polycrystalline features with increasing N-doping concentration. For the first time, we report here that N-doping in the Ni-deficient NiO (Ni{sub 1-x}O) film leads to a band-gap narrowing from 3.6 to 2.3 eV. X-ray photoelectron spectroscopy (XPS) measurements proved that up to 4 atomic percent (at.%) nitrogen can be incorporated at least at the surface of the NiO:N samples. In addition, XPS valence band spectra and UV–vis transmission measurements have demonstrated that the band-gap narrowing may originates from the contribution of an intermediate band (IB) ∼2.4 eV just above the valence band maximum and the up-shifting of the valence band edge (∼0.3 eV) due to the introduction of occupied N 2p states. Local I–V measurements, carried out by conductive AFM (C-AFM), have revealed that the extrinsic doping of N atoms within the oxide can be a good way to precisely control the electrical conductivity of such p-type materials.
Nitrogen-doped porous carbon derived from biomass waste for high-performance supercapacitor.

Science.gov (United States)

Ma, Guofu; Yang, Qian; Sun, Kanjun; Peng, Hui; Ran, Feitian; Zhao, Xiaolong; Lei, Ziqiang

2015-12-01

High capacitance property and low cost are the pivotal requirements for practical application of supercapacitor. In this paper, a low cost and high capacitance property nitrogen-doped porous carbon with high specific capacitance is prepared. The as-prepared nitrogen-doped porous carbon employing potato waste residue (PWR) as the carbon source, zinc chloride (ZnCl2) as the activating agent and melamine as nitrogen doping agent. The morphology and structure of the carbon materials are studied by scanning electron microscopy (SEM), N2 adsorption/desorption, X-ray diffraction (XRD) and Raman spectra. The surface area of the nitrogen-doped carbon which prepared under 700°C is found to be 1052m(2)/g, and the specific capacitance as high as 255Fg(-1) in 2M KOH electrolyte is obtained utilize the carbon as electrode materials. The electrode materials also show excellent cyclability with 93.7% coulombic efficiency at 5Ag(-1) current density of for 5000cycles. Copyright © 2015 Elsevier Ltd. All rights reserved.
Preparation of nitrogen-doped graphitic carboncages as electrocatalyst for oxygen reduction reaction

International Nuclear Information System (INIS)

Yan, Jing; Meng, Hui; Yu, Wendan; Yuan, Xiaoli; Lin, Worong; Ouyang, Wenpeng; Yuan, Dingsheng

2014-01-01

Nitrogen-doped carbon nanomaterials have been attracted increasing research interests in lithium-O 2 and Zinc-O 2 batteries, ultracapacitors and fuel cells. Herein, nitrogen-doped graphitic carboncages (N-GCs) have been prepared by mesoporous Fe 2 O 3 as a catalyst and lysine as a nitrogen doped carbon source. Due to the catalysis of Fe 2 O 3 , the N-GCs have a high graphitization degree at a low temperature, which is detected by X-ray diffraction and Raman spectrometer. Simultaneously, the heteroatom nitrogen is in-situ doped into carbon network. Therefore, the excellent electrocatalysis performance for oxygen reduction reaction is expected. The electrochemical measurement indicates that The N-GCs for oxygen reduction reaction in O 2 -saturated 0.1 mol L −1 KOH show a four-electron transfer process and exhibit excellent electrocatalytic activity (E ORR = -0.05 V vs. Ag/AgCl) and good stability (i/i 0 = 90% at -0.35 V after 4000 s with a rotation rate of 1600 rpm)
Role of nitrogen vacancies in cerium doped aluminum nitride

Energy Technology Data Exchange (ETDEWEB)

Majid, Abdul, E-mail: abdulmajid40@yahoo.com [Department of Physics, University of Gujrat, Gujrat (Pakistan); Department of Adaptive Machine Systems, Osaka University, Osaka (Japan); Asghar, Farzana [Department of Physics, University of Gujrat, Gujrat (Pakistan); Rana, Usman Ali; Ud-Din Khan, Salah [Sustainable Energy Technologies Center, College of Engineering, King Saud University, PO-Box 800, Riyadh 11421 (Saudi Arabia); Yoshiya, Masato [Department of Adaptive Machine Systems, Osaka University, Osaka (Japan); Hussain, Fayyaz [Physics Department, Bahauddin Zakarya University, Multan (Pakistan); Ahmad, Iftikhar [Department of Mathematics, University of Gujrat, Gujrat (Pakistan)

2016-08-15

In this report, a systematic density functional theory based investigation to explain the character of nitrogen vacancies in structural, electronic and magnetic properties of Ce doped wurtzite AlN is presented. The work demonstrates the modification in the properties of the material upon doping thereby addressing dopant concentration and inter-dopant distance. The presence of anionic vacancy reveals spin polarization and introduction of magnetic character in the structure. The doping produced the magnetic character in the material which was of ferromagnetic nature in most cases except the situation when dopants separated by largest distance of 5.873 Å. The calculated values of total energy and exchange energy suggested the configuration including Ce{sub Al}–V{sub N} complex is more favorable and exhibits ferromagnetic ordering. - Highlights: • Ce doped AlN with and without nitrogen vacancy. • Dopant at nearest neighbor site introduce ferromagnetism. • Ce{sub Al}–V{sub N} complex is favorable in Ce:AlN.
Role of nitrogen vacancies in cerium doped aluminum nitride

International Nuclear Information System (INIS)

Majid, Abdul; Asghar, Farzana; Rana, Usman Ali; Ud-Din Khan, Salah; Yoshiya, Masato; Hussain, Fayyaz; Ahmad, Iftikhar

2016-01-01

In this report, a systematic density functional theory based investigation to explain the character of nitrogen vacancies in structural, electronic and magnetic properties of Ce doped wurtzite AlN is presented. The work demonstrates the modification in the properties of the material upon doping thereby addressing dopant concentration and inter-dopant distance. The presence of anionic vacancy reveals spin polarization and introduction of magnetic character in the structure. The doping produced the magnetic character in the material which was of ferromagnetic nature in most cases except the situation when dopants separated by largest distance of 5.873 Å. The calculated values of total energy and exchange energy suggested the configuration including Ce Al –V N complex is more favorable and exhibits ferromagnetic ordering. - Highlights: • Ce doped AlN with and without nitrogen vacancy. • Dopant at nearest neighbor site introduce ferromagnetism. • Ce Al –V N complex is favorable in Ce:AlN.
The Synthesis of Nitrogen-Doped Multiwalled Carbon Nanotubes ...

African Journals Online (AJOL)

ACVDmethod was used to prepare high-quality nitrogen-doped multiwalled carbon nanotubes (N-MWCNTs) using acetonitrile as the nitrogen and carbon source and acetylene as a carbon source over an Fe-Co/CaCO3 catalyst in the temperature range 700–850 °C. This represents a continuation of earlier work in which ...
Boron and nitrogen doping of graphene via thermal exfoliation of graphite oxide in a BF3 or NH3 atmosphere: contrasting properties

Czech Academy of Sciences Publication Activity Database

Poh, H. L.; Šimek, P.; Sofer, Z.; Tomandl, Ivo; Pumera, M.

2013-01-01

Roč. 1, č. 42 (2013), s. 13146-13153 ISSN 2050-7488 R&D Projects: GA MŠk(XE) LM2011019 Institutional support: RVO:61389005 Keywords : Boron and nitrogen doping * Prompt gamma-ray activation analysis * Graphene lattices Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders
Electrochemical oxidation of nitrogen-heterocyclic compounds at boron-doped diamond electrode.

Science.gov (United States)

Xing, Xuan; Zhu, Xiuping; Li, Hongna; Jiang, Yi; Ni, Jinren

2012-01-01

Nitrogen-heterocyclic compounds (NHCs) are toxic and bio-refractory contaminants widely spread in environment. This study investigated electrochemical degradation of NHCs at boron-doped diamond (BDD) anode with particular attention to the effect of different number and position of nitrogen atoms in molecular structure. Five classical NHCs with similar structures including indole (ID), quinoline (QL), isoquinoline (IQL), benzotriazole (BT) and benzimidazole (BM) were selected as the target compounds. Results of bulk electrolysis showed that degradation of all NHCs was fit to a pseudo first-order equation. The five compounds were degraded with the following sequence: ID>QL>IQL>BT>BM in terms of their rates of oxidation. Quantum chemical calculation was combined with experimental results to describe the degradation character of NHCs at BDD anode. A linear relationship between degradation rate and delocalization energy was observed, which demonstrated that electronic charge was redistributed through the conjugation system and accumulated at the active sites under the attack of hydroxyl radicals produced at BDD anode. Moreover, atom charge was calculated by semi empirical PM3 method and active sites of NHCs were identified respectively. Analysis of intermediates by GC-MS showed agreement with calculation results. Copyright © 2011 Elsevier Ltd. All rights reserved.
Analisis Pengaruh Doping Nitrogen Terhadap Sifat Kapasitif Superkapasitor Berbahan Graphene

Directory of Open Access Journals (Sweden)

Diah Ayu Safitri

2017-03-01

Full Text Available Kebutuhan manusia akan barang elektronik semakin meningkat, sehingga meningkat pula kebutuhan akan media penyimpan listrik. Salah satu media penyimpan energy yaitu kapasitor. Electric Double Layer Capacitor (EDLC merupakan superkapasitor yang memiliki waktu hidup yang lebih lama, rapat daya dan kecepatan charging-discharging tinggi. Graphene telah banyak dieksplorasi sebagai material untuk EDLC, salah satunya yaitu dengan pendopingan. Penelitian ini bertujuan untuk menganalisis pengaruh doping nitrogen terhadap struktur dan morfologi serta pengaruh doping nitrogen terhadap sifat kapasitif dari elektroda superkapasitor berbahan Graphene. Sintesis graphene diawali dari grafit yang dioksidasi menjadi grafit oksida dengan metode Hummer. Grafit oksida lalu direduksi dengan metode hydrotermal menjadi graphene. Penelitian ini memvariasikan doping nitrogen dengan penambahan NH4OH 0.1 ml, 0.3 ml dan 1 ml. Material yang disintesis ini dikarakterisasi menggunakan XRD(X-Ray Diffraction, SEM (Scanning Electron Microscopy , EDS (Energy Disspersive X-Ray analysis, FPP (Four Point Probe, dan FTIR (Fourier Transform Infrared Spectroscopu. Dari hasil karakterisasi menunjukkan bahwa material yang disintesis adalah graphene. Sifat kapasitif Elektroda diukur dengan melakukan uji Cyclic Voltametry (CV dengan rentang scan rate 5, 10, 50 dan 100 mV/s. Dari hasil penelitian didapatkan doping nitrogen pada graphene yang paling optimal adalah dengan penambahan NH4OH 0.3 ml yaitu 5.2%at dengan nilai kapasitansi sebesar 208.47 F/g.

In Situ One-Step Synthesis of Hierarchical Nitrogen-Doped Porous Carbon for High Performance Supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Jeon, Ju Won [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Texas A & M Univ., College Station, TX (United States); Sharma, Ronish [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Meduri, Praveen [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Arey, Bruce W. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Schaef, Herbert T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lutkenhaus, Jodie [Texas A & M Univ., College Station, TX (United States); Lemmon, John P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Thallapally, Praveen K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Nandasiri, Manjula I. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McGrail, B. Peter [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Nune, Satish K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2014-04-30

Electrochemical performance of the existing state-of-the art capacitors is not very high, key scientific barrier is that its charge storage mechanism wholly depends on adsorption of electrolyte on electrode. We present a novel method for the synthesis of nitrogen -doped porous carbons and address the drawback by precisely controlling composition and surface area. Nitrogen-doped porous carbon was synthesized using a self-sacrificial template technique without any additional nitrogen and carbon sources. They exhibited exceptionally high capacitance (239 Fg-1) due to additional pseudocapacitance originating from doped nitrogen. Cycling tests showed no obvious capacitance decay even after 10,000 cycles, which meets the requirement of commercial supercapacitors. Our method is simple and highly efficient for the production of large quantities of nitrogen-doped porous carbons.
A facile fabrication of nitrogen-doped electrospun In{sub 2}O{sub 3} nanofibers with improved visible-light photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Lu, Na; Shao, Changlu, E-mail: clshao@nenu.edu.cn; Li, Xinghua, E-mail: lixh781@nenu.edu.cn; Miao, Fujun; Wang, Kexin; Liu, Yichun

2017-01-01

Highlights: • N-doped In{sub 2}O{sub 3} nanofibers are facilely fabricated by gaseous ammonia treatment. • Adjusting the annealing temperature leads to different N-doped In{sub 2}O{sub 3} nanofibers. • Nitrogen doping was found to be interstitial mode. • N-In{sub 2}O{sub 3} exhibited effective charge carrier separation and photocatalytic activity. • The photocatalysts can be easily separated from the reaction system. - Abstract: Semiconductor photocatalysis demonstrates to be an effective approach for eliminating most types of environment contaminants and for producing hydrogen. Herein, a facile synthesis route combining electrospinning technique and thermal treatment method under NH{sub 3} atmosphere has been presented as a straightforward protocol for the fabrication of nitrogen-doped In{sub 2}O{sub 3} (N-In{sub 2}O{sub 3}) nanofibers, the nitrogen content of which can be well controlled by adjusting the annealing temperature. Photocatalytic tests show that the N-In{sub 2}O{sub 3} nanofibers demonstrate an improved degradation rate of Rhodamine B (RB) compared with pure In{sub 2}O{sub 3} nanofibers under visible-light irradiation. This can be attributed to the nitrogen atom introducing at interstitial sites as well as the generation of oxygen vacancy on the surface of In{sub 2}O{sub 3} nanofibers, resulting in the enhanced utilization of visible light for the N-In{sub 2}O{sub 3} nanofibers. Furthermore, the obtained N-In{sub 2}O{sub 3} nanofibers with the advantage of ultra-long one-dimensional nanostructures can be recycled several times by facile sedimentation and hence present almost no decrease in photocatalytic activity indicative of a well regeneration capability. Therefore, the as-fabricated nitrogen-doped In{sub 2}O{sub 3} nanofibers as a promising photocatalyst present good photocatalytic degradation of organic pollutant in waste water for practical application.
Nitrogen doping of chemical vapor deposition grown graphene on 4H-SiC (0001)

Energy Technology Data Exchange (ETDEWEB)

Urban, J. M.; Binder, J.; Wysmołek, A. [Faculty of Physics, University of Warsaw, ul. Hoża 69, 00-681 Warsaw (Poland); Dąbrowski, P.; Strupiński, W. [Institute of Electronic Materials Technology, ul. Wólczyńska 133, 01-919 Warsaw (Poland); Kopciuszyński, M.; Jałochowski, M. [Institute of Physics, Maria Curie-Skłodowska University, pl. M. Curie-Skłodowskiej 1, 20-031 Lublin (Poland); Klusek, Z. [Faculty of Physics and Applied Informatics, University of Łódź, ul. Pomorska 149/153, 90-236 Łódź (Poland); Baranowski, J. M. [Faculty of Physics, University of Warsaw, ul. Hoża 69, 00-681 Warsaw (Poland); Institute of Electronic Materials Technology, ul. Wólczyńska 133, 01-919 Warsaw (Poland)

2014-06-21

We present optical, electrical, and structural properties of nitrogen-doped graphene grown on the Si face of 4H-SiC (0001) by chemical vapor deposition method using propane as the carbon precursor and N{sub 2} as the nitrogen source. The incorporation of nitrogen in the carbon lattice was confirmed by X-ray photoelectron spectroscopy. Angle-resolved photoemission spectroscopy shows carrier behavior characteristic for massless Dirac fermions and confirms the presence of a graphene monolayer in the investigated nitrogen-doped samples. The structural and electronic properties of the material were investigated by Raman spectroscopy. A systematical analysis of the graphene Raman spectra, including D, G, and 2D bands, was performed. In the case of nitrogen-doped samples, an electron concentration on the order of 5–10 × 10{sup 12} cm{sup −2} was estimated based upon Raman and Hall effect measurements and no clear dependence of the carrier concentration on nitrogen concentration used during growth was observed. This high electron concentration can be interpreted as both due to the presence of nitrogen in graphitic-like positions of the graphene lattice as well as to the interaction with the substrate. A greater intensity of the Raman D band and increased inhomogeneity, as well as decreased electron mobility, observed for nitrogen-doped samples, indicate the formation of defects and a modification of the growth process induced by nitrogen doping.
Three Dimensional Nitrogen-Doped and Nitrogen, Sulfur-Codoped Graphene Hydrogels for Electrode Materials in Supercapacitors.

Science.gov (United States)

Yuan, Zhao; Qiao, Fei; Wang, Guiqiang; Zhou, Jin; Cui, Hongyou; Zhuo, Shuping; Xing, Ling-Bao

2018-08-01

In present work, reduced graphene oxide hydrogels (RGOHs) with three-dimensional (3D) porous structure are prepared through chemical reduction method by using aminourea (NRGOHs) and aminothiourea (NSRGOHs) as reductants. The as-prepared RGOHs are considered not only as promising electrode materials for supercapacitors, but also the doping of nitrogen (aminourea, NRGOHs) or nitrogen/sulfur (aminothiourea, NSRGOHs) can improve electrochemical performance through faradaic pseudocapacitance. The optimized samples have been prepared by controlling the mass ratios of graphene oxide (GO) to aminourea or aminothiourea to be 1:1, 1:2 and 1:5, respectively. With adding different amounts of aminourea or aminothiourea, the obtained RGOHs exhibited different electrochemical performance in supercapacitors. With increasing the dosage of the reductants, the RGOHs revealed better specific capacitances. Moreover, NSRGOHs with nitrogen, sulfur-codoping exhibited better capacitance performance than that of NRGOHs with only nitrogen-doping. NSRGOHs showed excellent capacitive performance with a very high specific capacitance up to 232.2, 323.3 and 345.6 F g-1 at 0.2 A g-1, while NRGOHs showed capacitive performance with specific capacitance up to 220.6, 306.5 and 332.7 F g-1 at 0.2 A g-1. This provides a strategy to improve the capacitive properties of RGOHs significantly by controlling different doping the materials.
Nitrogen and vanadium Co-doped TiO{sub 2} mesosponge layers for enhancement in visible photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Jiasong Zhong [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310018 (China); Xu, Jinrong [Department of Mathematics and Physics, Anhui University of Architecture, Hefei, 230022 (China); Wang, Qingyao, E-mail: wangqingyao0532@163.com [School of Chemistry and Materials Science, Ludong University, Yantai, 264025 (China)

2014-10-01

Graphical abstract: - Highlights: • N and V co-doped TiO{sub 2} mesosponges were prepared by hydrothermal method. • The first-principle was used to investigate the novel porous materials. • N-V-TMSW had a remarkable visible absorption and photocatalytic activity. - Abstract: Novel N and V co-doped TiO{sub 2} mesosponge (N-V-TMSW) layers were successfully prepared by one-step hydrothermal treatment of TiO{sub 2} nanotube arrays, and the phase composition, morphology and optical property were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) and UV–vis diffusion reflectance spectroscopy (DRS). The crystal structure and density of states were studied by means of the first-principle pseudo-potential plane wave. The results indicated that titanium ions and oxygen atoms in TiO{sub 2} were successfully substituted by vanadium ions and nitrogen atoms, respectively. The sample N-V0.1-TMSW showed a remarkable absorption in the visible light range of 400–600 nm and high visible photocatalytic activity.
Unusually high dispersion of nitrogen-doped carbon nanotubes in DNA solution.

Science.gov (United States)

Kim, Jin Hee; Kataoka, Masakazu; Fujisawa, Kazunori; Tojo, Tomohiro; Muramatsu, Hiroyuki; Vega-Díaz, Sofía M; Tristán-López, F; Hayashi, Takuya; Kim, Yoong Ahm; Endo, Morinobu; Terrones, Mauricio; Dresselhaus, Mildred S

2011-12-08

The dispersibility in a DNA solution of bundled multiwalled carbon nanotubes (MWCNTs), having different chemical functional groups on the CNT sidewall, was investigated by optical spectroscopy. We observed that the dispersibility of nitrogen (N)-doped MWCNTs was significantly higher than that of pure MWCNTs and MWCNTs synthesized in the presence of ethanol. This result is supported by the larger amount of adsorbed DNA on N-doped MWCNTs, as well as by the higher binding energy established between nucleobases and the N-doped CNTs. Pure MWCNTs are dispersed in DNA solution via van der Waals and hydrophobic interactions; in contrast, the nitrogenated sites within N-doped MWCNTs provided additional sites for interactions that are important to disperse nanotubes in DNA solutions. © 2011 American Chemical Society
On the electrocatalytic activity of nitrogen-doped reduced graphene ...

Indian Academy of Sciences (India)

The heteroatom-doped graphene/reduced graphene oxide (rGO)is very promising and the nitrogen-doped rGO (N-rGO) is emerging as a new inexpensive electrocatalyst foroxygen reduction reaction (ORR). Herein, we describe the effect of the chemical nature and amount of nitrogenin N-rGO towards ORR in acidic solution ...
Electrical current at micro-/macro-scale of undoped and nitrogen-doped MWPECVD diamond films

Science.gov (United States)

Cicala, G.; Velardi, L.; Senesi, G. S.; Picca, R. A.; Cioffi, N.

2017-12-01

Chemical, structural, morphological and micro-/macro-electrical properties of undoped and nitrogen-(N-)doped diamond films are determined by X-ray photoelectron spectroscopy, Raman and photoluminescence spectroscopies, field emission scanning electron microscopy, atomic force microscopy, scanning capacitance microscopy (SCM) and two points technique for I-V characteristics, respectively. The characterization results are very useful to examine and understand the relationship among these properties. The effect of the nitrogen incorporation in diamond films is investigated through the evolution of the chemical, structural, morphological and topographical features and of the electrical behavior. The distribution of the electrical current is first assessed at millimeter scale on the surface of diamond films and then at micrometer scale on small regions in order to establish the sites where the carriers preferentially move. Specifically, the SCM images indicate a non-uniform distribution of carriers on the morphological structures mainly located along the grain boundaries. A good agreement is found by comparing the electrical currents at the micro- and macro-scale. This work aims to highlight phenomena such as photo- and thermionic emission from N-doped diamond useful for microelectronic engineering.
The Synergistic Effect of Nitrogen Dopant and Calcination Temperature on the Visible-Light-Induced Photoactivity of N-Doped TiO2

Directory of Open Access Journals (Sweden)

Yao-Tung Lin

2013-01-01

Full Text Available The synergistic effect of nitrogen content and calcinations temperature on the N-doped TiO2 catalysts prepared by sol-gel method was investigated. The phase and structure, chemical state, optical properties, and surface area/pore distribution of N-doped TiO2 were characterized using X-ray diffraction spectrometer, high-resolution transmission electron microscope, X-ray photoelectron spectroscopy, UV-vis diffusion reflectance spectroscopy, and Brunauer-Emmett-Teller specific surface area. Finding showed that the photocatalytic activity of N-doped TiO2 was greatly enhanced compared to pure TiO2 under visible irradiation. N dopants could retard the transformation from anatase to rutile phase. Namely, N-doping effect is attributed to the anatase phase stabilization. The results showed nitrogen atoms were incorporated into the interstitial positions of the TiO2 lattice. Ethylene was used to evaluate the photocatalytic activity of samples under visible-light illumination. The results suggested good anatase crystallization, smaller particle size, and larger surface are beneficial for photocatalytic activity of N-doped TiO2. The N-doped TiO2 catalyst prepared with ammonia to titanium isopropoxide molar ratio of 2.0 and calcinated at 400°C showed the best photocatalytic ability.
Influence of nitrogen doping in sumanene framework toward hydrogen storage: A computational study.

Science.gov (United States)

Reisi-Vanani, Adel; Shamsali, Fatemeh

2017-09-01

Two conditions are important to obtain appropriate substances for hydrogen storage; high surface area and fitting binding energy (BE). Doping is a key strategy that improves BE. We investigated hydrogen adsorption onto twenty six nitrogen disubstituted isomers of sumanene (C 19 N 2 H 12 ) by MP2/6-311++G(d,p)//B3LYP/6-31+G(d) and M06-2X/6-31+G(d) levels of theory. Effect of nitrogen doping in different positions of sumanene was checked. To obtain better BE, basis set superposition error (BSSE) and zero point energy (ZPE) corrections were used. Anticipating of adsorption sites and extra details about adsorption process was done by molecular electrostatic potential (MEP) surfaces. Various types of density of state (DOS) diagrams such as total DOS (TDOS), projected DOS (PDOS) and overlap population DOS (OPDOS) and natural bond orbital (NBO) analysis were used to find better insight on the adsorption properties. In addition of temperature depending of the BE, HOMO-LUMO gap (HLG), dipole moment, reactivity and stability, bowl depth and natural population analysis (NPA) of the isomers were studied. A physisorption mechanism for adsorption was proposed and a trivial change was seen. Place of nitrogen atoms in sumanene frame causes to binding energy increases or decreases compared with pristine sumanene. The best and the worst isomers and category of isomers were suggested. Copyright © 2017 Elsevier Inc. All rights reserved.
Phosphorus {delta}-doped silicon: mixed-atom pseudopotentials and dopant disorder effects

Energy Technology Data Exchange (ETDEWEB)

Carter, Damien J; Marks, Nigel A [Nanochemistry Research Institute, Curtin University, PO Box U1987, Perth WA 6845 (Australia); Warschkow, Oliver; McKenzie, David R, E-mail: d.carter@curtin.edu.au [Centre for Quantum Computer Technology, School of Physics, University of Sydney, Sydney, NSW 2006 (Australia)

2011-02-11

Within a full density functional theory framework we calculate the band structure and doping potential for phosphorus {delta}-doped silicon. We compare two different representations of the dopant plane; pseudo-atoms in which the nuclear charge is fractional between silicon and phosphorus, and explicit arrangements employing distinct silicon and phosphorus atoms. While the pseudo-atom approach offers several computational advantages, the explicit model calculations differ in a number of key points, including the valley splitting, the Fermi level and the width of the doping potential. These findings have implications for parameters used in device modelling.
Nitrogen-Doped Three Dimensional Graphene for Electrochemical Sensing.

Science.gov (United States)

Yan, Jing; Chen, Ruwen; Liang, Qionglin; Li, Jinghong

2015-07-01

The rational assembly and doping of graphene play an crucial role in the improvement of electrochemical performance for analytical applications. Covalent assembly of graphene into ordered hierarchical structure provides an interconnected three dimensional conductive network and large specific area beneficial to electrolyte transfer on the electrode surface. Chemical doping with heteroatom is a powerful tool to intrinsically modify the electronic properties of graphene due to the increased free charge-carrier densities. By incorporating covalent assembly and nitrogen doping strategy, a novel nitrogen doped three dimensional reduced graphene oxide nanostructure (3D-N-RGO) was developed with synergetic enhancement in electrochemical behaviors. The as prepared 3D-N-RGO was further applied for catechol detection by differential pulse voltammetry. It exhibits much higher electrocatalytic activity towards catechol with increased peak current and decreased potential difference between the oxidation and reduction peaks. Owing to the improved electro-chemical properties, the response of the electrochemical sensor varies linearly with the catechol concentrations ranging from 5 µM to 100 µM with a detection limit of 2 µM (S/N = 3). This work is promising to open new possibilities in the study of novel graphene nanostructure and promote its potential electrochemical applications.
Nano-Architecture of nitrogen-doped graphene films synthesized from a solid CN source.

Science.gov (United States)

Maddi, Chiranjeevi; Bourquard, Florent; Barnier, Vincent; Avila, José; Asensio, Maria-Carmen; Tite, Teddy; Donnet, Christophe; Garrelie, Florence

2018-02-19

New synthesis routes to tailor graphene properties by controlling the concentration and chemical configuration of dopants show great promise. Herein we report the direct reproducible synthesis of 2-3% nitrogen-doped 'few-layer' graphene from a solid state nitrogen carbide a-C:N source synthesized by femtosecond pulsed laser ablation. Analytical investigations, including synchrotron facilities, made it possible to identify the configuration and chemistry of the nitrogen-doped graphene films. Auger mapping successfully quantified the 2D distribution of the number of graphene layers over the surface, and hence offers a new original way to probe the architecture of graphene sheets. The films mainly consist in a Bernal ABA stacking three-layer architecture, with a layer number distribution ranging from 2 to 6. Nitrogen doping affects the charge carrier distribution but has no significant effects on the number of lattice defects or disorders, compared to undoped graphene synthetized in similar conditions. Pyridinic, quaternary and pyrrolic nitrogen are the dominant chemical configurations, pyridinic N being preponderant at the scale of the film architecture. This work opens highly promising perspectives for the development of self-organized nitrogen-doped graphene materials, as synthetized from solid carbon nitride, with various functionalities, and for the characterization of 2D materials using a significant new methodology.
Industrialization of the nitrogen-doping preparation for SRF cavities for LCLS-II

Science.gov (United States)

Gonnella, D.; Aderhold, S.; Burrill, A.; Daly, E.; Davis, K.; Grassellino, A.; Grimm, C.; Khabiboulline, T.; Marhauser, F.; Melnychuk, O.; Palczewski, A.; Posen, S.; Ross, M.; Sergatskov, D.; Sukhanov, A.; Trenikhina, Y.; Wilson, K. M.

2018-03-01

The Linac Coherent Light Source II (LCLS-II) is a new state-of-the-art coherent X-ray source being constructed at SLAC National Accelerator Laboratory. It employs 280 superconducting radio frequency (SRF) cavities in order operate in continuous wave (CW) mode. To reduce the overall cryogenic cost of such a large accelerator, nitrogen-doping of the SRF cavities is being used. Nitrogen-doping has consistently been shown to increase the efficiency of SRF cavities operating in the 2.0 K regime and at medium fields (15-20 MV/m) in vertical cavity tests and horizontal cryomodule tests. While nitrogen-doping's efficacy for improvement of cavity performance was demonstrated at three independent labs, Fermilab, Jefferson Lab, and Cornell University, transfer of the technology to industry for LCLS-II production was not without challenges. Here we present results from the beginning of LCLS-II cavity production. We discuss qualification of the cavity vendors and the first cavities from each vendor. Finally, we demonstrate that nitrogen-doping has been successfully transferred to SRF cavity vendors, resulting in consistent production of cavities with better cryogenic efficiency than has ever been achieved for a large-scale accelerator.
Effect of reaction temperature on structure and fluorescence properties of nitrogen-doped carbon dots

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yi [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Department of Chemistry and Chemical Engineering, Lyuliang University, Lyuliang 033001 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Wang, Yaling [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Feng, Xiaoting [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Zhang, Feng [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Yang, Yongzhen, E-mail: yyztyut@126.com [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Liu, Xuguang, E-mail: liuxuguang@tyut.edu.cn [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China)

2016-11-30

Highlights: • Nitrogen-doped carbon dots (NCDs) from ammonia solution and citric acid were synthesized at different temperatures. • Quantum yield (QY) of NCDs depends largely on the amount of fluorescent polymer chains (FPC), more FPC gives higher QY. • The law of QY of NCDs first increase and then decrease with the reaction temperature increased is found and explained. • Nitrogen doping plays significant role in getting increased UV–vis absorption and QY. - Abstract: To investigate the effect of reaction temperature and nitrogen doping on the structure and fluorescence properties of carbon dots (CDs), six kinds of nitrogen-doped CDs (NCDs) were synthesized at reaction temperatures of 120, 140, 160, 180, 200 and 220 °C, separately, by using citric acid as carbon source and ammonia solution as nitrogen source. Nitrogen-free CDs (N-free CDs-180) was also prepared at 180 °C by using citric acid as the only carbon source for comparison. Results show that reaction temperature has obvious effect on carbonization degree, quantum yield (QY), ultraviolet-visible (UV–vis) absorption and photoluminescence (PL) spectra but less effect on functional groups, nitrogen doping degree and fluorescence lifetime of NCDs. Compared with N-free CDs-180, NCDs-180 possesses enchanced QY and longer fluorescence lifetime. Doping nitrogen has obvious effect on UV–vis absorption and PL spectra but less effect on particles sizes and carbonization degree. The formation mechanism of NCDs is explored: QY of NCDs depends largely on the number of fluorescent polymer chains (FPC), the competition between FPC formation on the surface of NCDs and carbon core growth leads to the change in number of FPC, and consequently to the NCDs with highest QY at appropriate hydrothermal temperature.
Site-selective substitutional doping with atomic precision on stepped Al (111) surface by single-atom manipulation.

Science.gov (United States)

Chen, Chang; Zhang, Jinhu; Dong, Guofeng; Shao, Hezhu; Ning, Bo-Yuan; Zhao, Li; Ning, Xi-Jing; Zhuang, Jun

2014-01-01

In fabrication of nano- and quantum devices, it is sometimes critical to position individual dopants at certain sites precisely to obtain the specific or enhanced functionalities. With first-principles simulations, we propose a method for substitutional doping of individual atom at a certain position on a stepped metal surface by single-atom manipulation. A selected atom at the step of Al (111) surface could be extracted vertically with an Al trimer-apex tip, and then the dopant atom will be positioned to this site. The details of the entire process including potential energy curves are given, which suggests the reliability of the proposed single-atom doping method.
Nanostructured nitrogen-doped mesoporous carbon derived from polyacrylonitrile for advanced lithium sulfur batteries

Energy Technology Data Exchange (ETDEWEB)

Liu, Ying; Zhao, Xiaohui; Chauhan, Ghanshyam S. [Department of Chemical Engineering and Research Institute for Green Energy Convergence Technology, Gyeongsang National University, 501 Jinju-daero, Jinju 660-701 (Korea, Republic of); Ahn, Jou-Hyeon, E-mail: jhahn@gnu.ac.kr [Department of Chemical Engineering and Research Institute for Green Energy Convergence Technology, Gyeongsang National University, 501 Jinju-daero, Jinju 660-701 (Korea, Republic of); Department of Materials Engineering and Convergence Technology and RIGET, Gyeongsang National University, 501 Jinju-daero, Jinju 660-701 (Korea, Republic of)

2016-09-01

Graphical abstract: Well-ordered nitrogen-doped mesoporous carbon materials were prepared by in-situ polymerization of polyacrylonitrile in SBA-15 template. The composite of sulfur and nitrogen-doped carbon was successfully used as a cathode material for lithium sulfur battery. - Highlights: • N-doped mesoporous carbons were prepared with PAN as carbon source. • Highly ordered pore system facilitates sulfur loading. • Ladder-type carbon matrix provides good structural stability for confining sulfur. • N-doping ensures an improved absorbability of soluble polysulfides. - Abstract: Nitrogen doping in carbon matrix can effectively improve the wettability of electrolyte and increase electric conductivity of carbon by ensuring fast transfer of ions. We synthesized a series of nitrogen-doped mesoporous carbons (CPANs) via in situ polymerization of polyacrylonitrile (PAN) in SBA-15 template followed by carbonization at different temperatures. Carbonization results in the formation of ladder structure which enhances the stability of the matrix. In this study, CPAN-800, carbon matrix synthesized by the carbonization at 800 °C, was found to possess many desirable properties such as high specific surface area and pore volume, moderate nitrogen content, and highly ordered mesoporous structure. Therefore, it was used to prepare S/CPAN-800 composite as cathode material in lithium sulfur (Li-S) batteries. The S/CPAN-800 composite was proved to be an excellent material for Li-S cells which delivered a high initial discharge capacity of 1585 mAh g{sup −1} and enhanced capacity retention of 862 mAh g{sup −1} at 0.1 C after 100 cycles.
Nitrogen-doped porous “green carbon” derived from shrimp shell: Combined effects of pore sizes and nitrogen doping on the performance of lithium sulfur battery

Energy Technology Data Exchange (ETDEWEB)

Qu, Jiangying, E-mail: qujy@lnnu.edu.cn [Faculty of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029 (China); Carbon Research Laboratory, Center for Nano Materials and Science, School of Chemical Engineering, State Key Lab of Fine Chemicals, Dalian University of Technology, Dalian, 116024 (China); Lv, Siyuan; Peng, Xiyue; Tian, Shuo; Wang, Jia [Faculty of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029 (China); Gao, Feng, E-mail: fenggao2003@163.com [Faculty of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029 (China); Carbon Research Laboratory, Center for Nano Materials and Science, School of Chemical Engineering, State Key Lab of Fine Chemicals, Dalian University of Technology, Dalian, 116024 (China)

2016-06-25

Nitrogen-rich porous “green carbons” derived from abundant shrimp shell shows good performance for Li–S batteries. The strategy in this work is highlighted to selective removal of intrinsic CaCO{sub 3} in shrimp shell followed by KOH activation to tune the pore sizes of the obtained carbons. On the basis of the different porous structures, the discharge capacity of the obtained carbons as Li–S cathodes follows the order of micro-mesoporous carbon>mesoporous carbon>microporous carbon. The high capacity of the micro-mesoporous carbon is attributed to its positive characters such as the coexistence of micro-mesoporous structure, the large pore volume and the high specific surface area. Furthermore, well-dispersed nitrogen in the porous carbons is naturally doped and inherited from shrimp shell, and can help to enhance cycle stability when used as cathodes. As a result, all carbon cathodes exhibit the good cycle stability (>78%) due to their nitrogen doping induced chemical adsorption of sulfur on the surface areas of the porous carbons. Among them, mesoporous carbon cathode shows the best cycle stability with 90% retention within 100 cycles, which is mainly attributed to the synergistic effects of its both large pore size (5.12 nm) and high nitrogen content (6.67 wt %). - Highlights: • Nitrogen-rich porous “green carbons” derived from abundant shrimp shell shows good performance for Li–S batteries. • Intrinsic CaCO{sub 3} in shrimp shell as the natural template plays an important role on tailoring of the pore sizes of the porous carbons. • Nitrogen containing polysaccharide in shrimp shell benefits to produce nitrogen-rich carbons. • The effects of pore sizes on the electrochemical performance are investigated in detail. • The carbon-sulfur cathodes exhibit the good cycle stability because of nitrogen doping induced chemical adsorption of sulfur.
Nitrogen-doped porous “green carbon” derived from shrimp shell: Combined effects of pore sizes and nitrogen doping on the performance of lithium sulfur battery

International Nuclear Information System (INIS)

Qu, Jiangying; Lv, Siyuan; Peng, Xiyue; Tian, Shuo; Wang, Jia; Gao, Feng

2016-01-01

Nitrogen-rich porous “green carbons” derived from abundant shrimp shell shows good performance for Li–S batteries. The strategy in this work is highlighted to selective removal of intrinsic CaCO_3 in shrimp shell followed by KOH activation to tune the pore sizes of the obtained carbons. On the basis of the different porous structures, the discharge capacity of the obtained carbons as Li–S cathodes follows the order of micro-mesoporous carbon>mesoporous carbon>microporous carbon. The high capacity of the micro-mesoporous carbon is attributed to its positive characters such as the coexistence of micro-mesoporous structure, the large pore volume and the high specific surface area. Furthermore, well-dispersed nitrogen in the porous carbons is naturally doped and inherited from shrimp shell, and can help to enhance cycle stability when used as cathodes. As a result, all carbon cathodes exhibit the good cycle stability (>78%) due to their nitrogen doping induced chemical adsorption of sulfur on the surface areas of the porous carbons. Among them, mesoporous carbon cathode shows the best cycle stability with 90% retention within 100 cycles, which is mainly attributed to the synergistic effects of its both large pore size (5.12 nm) and high nitrogen content (6.67 wt %). - Highlights: • Nitrogen-rich porous “green carbons” derived from abundant shrimp shell shows good performance for Li–S batteries. • Intrinsic CaCO_3 in shrimp shell as the natural template plays an important role on tailoring of the pore sizes of the porous carbons. • Nitrogen containing polysaccharide in shrimp shell benefits to produce nitrogen-rich carbons. • The effects of pore sizes on the electrochemical performance are investigated in detail. • The carbon-sulfur cathodes exhibit the good cycle stability because of nitrogen doping induced chemical adsorption of sulfur.
Hydrothermal synthesis of highly nitrogen-doped few-layer graphene via solid–gas reaction

International Nuclear Information System (INIS)

Liang, Xianqing; Zhong, Jun; Shi, Yalin; Guo, Jin; Huang, Guolong; Hong, Caihao; Zhao, Yidong

2015-01-01

Highlights: • A novel approach to synthesis of N-doped few-layer graphene has been developed. • The high doping levels of N in products are achieved. • XPS and XANES results reveal a thermal transformation of N bonding configurations. • The developed method is cost-effective and eco-friendly. - Abstract: Nitrogen-doped (N-doped) graphene sheets with high doping concentration were facilely synthesized through solid–gas reaction of graphene oxide (GO) with ammonia vapor in a self-designed hydrothermal system. The morphology, surface chemistry and electronic structure of N-doped graphene sheets were investigated by TEM, AFM, XRD, XPS, XANES and Raman characterizations. Upon hydrothermal treatment, up to 13.22 at% of nitrogen could be introduced into the crumpled few-layer graphene sheets. Both XPS and XANES analysis reveal that the reaction between oxygen functional groups in GO and ammonia vapor produces amide and amine species in hydrothermally treated GO (HTGO). Subsequent thermal annealing of the resultant HTGO introduces a gradual transformation of nitrogen bonding configurations in graphene sheets from amine N to pyridinic and graphitic N with the increase of annealing temperature. This study provides a simple but cost-effective and eco-friendly method to prepare N-doped graphene materials in large-scale for potential applications

Spectroscopic properties of nitrogen doped hydrogenated amorphous carbon films grown by radio frequency plasma-enhanced chemical vapor deposition

International Nuclear Information System (INIS)

Hayashi, Y.; Yu, G.; Rahman, M. M.; Krishna, K. M.; Soga, T.; Jimbo, T.; Umeno, M.

2001-01-01

Nitrogen doped hydrogenated amorphous carbon thin films have been deposited by rf plasma-enhanced chemical vapor deposition using CH 4 as the source of carbon and with different nitrogen flow rates (N 2 /CH 4 gas ratios between 0 and 3), at 300 K. The dependence modifications of the optical and the structural properties on nitrogen incorporation were investigated using different spectroscopic techniques, such as, Raman spectroscopy, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, ultraviolet-visible (UV-VIS) spectroscopy, electron spin resonance (ESR), photoluminescence (PL) and spectroscopic ellipsometry (SE). Raman spectroscopy and IR absorption reveal an increase in sp 2 -bonded carbon or a change in sp 2 domain size with increasing nitrogen flow rate. It is found that the configuration of nitrogen atoms incorporated into an amorphous carbon network gradually changes from nitrogen atoms surrounded by three (σ bonded) to two (π bonded) neighboring carbons with increasing nitrogen flow rate. Tauc optical gap is reduced from 2.6 to 2.0 eV, and the ESR spin density and the peak-to-peak linewidth increase sharply with increasing nitrogen flow rate. Excellent agreement has been found between the measured SE data and modeled spectra, in which an empirical dielectric function of amorphous materials and a linear void distribution along the thickness have been assumed. The influence of nitrogen on the electronic density of states is explained based on the optical properties measured by UV-VIS and PL including nitrogen lone pair band. [copyright] 2001 American Institute of Physics
Plasma-assisted nitrogen doping of VACNTs for efficiently enhancing the supercapacitor performance

Energy Technology Data Exchange (ETDEWEB)

Mashayekhi, Alireza; Hosseini, Seyed Mahmoud [University of Tehran, Nano-fabricated Energy Devices Laboratory, School of Electrical and Computer Engineering, College of Engineering (Iran, Islamic Republic of); Hassanpour Amiri, Morteza; Namdar, Naser [University of Tehran, Thin Film and Nano-electronics Laboratory, Nano-electronics Centre of Excellence, School of Electrical and Computer Engineering, College of Engineering (Iran, Islamic Republic of); Sanaee, Zeinab, E-mail: z.sanaee@ut.ac.ir [University of Tehran, Nano-fabricated Energy Devices Laboratory, School of Electrical and Computer Engineering, College of Engineering (Iran, Islamic Republic of)

2016-06-15

Nitrogen doping of vertically aligned carbon nanotubes (VACNTs) using plasma-enhanced chemical vapour deposition has been investigated to improve the supercapacitance performance of CNTs. Incorporating electrochemical measurements on the open-ended nitrogen-doped CNTs, showed the achievement of 6 times improvement in the capacitance value. For nitrogen-doped CNTs on silicon substrate, specific capacitance of 60 F g{sup −1} was obtained in 0.5 M KCl solution, with capacity retention ratio above 90 % after cycled at 0.1 A g{sup −1} for 5000 cycles. Using this sample, a symmetric supercapacitance was fabricated which showed the power density of 37.5 kW kg{sup −1}. The facile fabrication approach and its excellent capacitance improvement, propose it as an efficient technique for enhancing the supercapacitance performance of the carbon-based electrodes.
Nitrogen plasma-treated multilayer graphene-based field effect transistor fabrication and electronic characteristics

Science.gov (United States)

Su, Wei-Jhih; Chang, Hsuan-Chen; Honda, Shin-ichi; Lin, Pao-Hung; Huang, Ying-Sheng; Lee, Kuei-Yi

2017-08-01

Chemical doping with hetero-atoms is an effective method used to change the characteristics of materials. Nitrogen doping technology plays a critical role in regulating the electronic properties of graphene. Nitrogen plasma treatment was used in this work to dope nitrogen atoms to modulate multilayer graphene electrical properties. The measured I-V multilayer graphene-base field-effect transistor characteristics (GFETs) showed a V-shaped transfer curve with the hole and electron region separated from the measured current-voltage (I-V) minimum. GFETs fabricated with multilayer graphene from chemical vapor deposition (CVD) exhibited p-type behavior because of oxygen adsorption. After using different nitrogen plasma treatment times, the minimum in I-V characteristic shifted into the negative gate voltage region with increased nitrogen concentration and the GFET channel became an n-type semiconductor. GFETs could be easily fabricated using this method with potential for various applications. The GFET transfer characteristics could be tuned precisely by adjusting the nitrogen plasma treatment time.
Synthesis of Nitrogen-doped Carbon Nanotubes with Layered ...

African Journals Online (AJOL)

NICO

Nitrogen-doped carbon nanotubes (CNx) were synthesized by the catalytic chemical vapour deposition ... dispersed metal nanoparticles over oxide matrices can be obtained ..... 18 S.Y. Kim, J. Lee, C.W. Na, J. Park, K. Seo and B. Kim, Chem.
Oxygen vacancy rich Cu2O based composite material with nitrogen doped carbon as matrix for photocatalytic H2 production and organic pollutant removal.

Science.gov (United States)

Lu, Lele; Xu, Xinxin; Yan, Jiaming; Shi, Fa-Nian; Huo, Yuqiu

2018-02-06

A nitrogen doped carbon matrix supported Cu 2 O composite material (Cu/Cu2O@NC) was fabricated successfully with a coordination polymer as precursor through calcination. In this composite material, Cu 2 O particles with a size of about 6-10 nm were dispersed evenly in the nitrogen doped carbon matrix. After calcination, some coordinated nitrogen atoms were doped in the lattice of Cu 2 O and replace oxygen atoms, thus generating a large number of oxygen vacancies. In Cu/Cu2O@NC, the existence of oxygen vacancies has been confirmed by electron spin resonance (ESR) and X-ray photoelectron spectroscopy (XPS). Under visible light irradiation, Cu/Cu2O@NC exhibits excellent H 2 production with the rate of 379.6 μmol h -1 g -1 . Its photocatalytic activity affects organic dyes, such as Rhodamine B (RhB) and methyl orange (MO). In addition to photocatalysis, Cu/Cu2O@NC also exhibits striking catalytic activity in reductive conversion of 4-nitrophenol to 4-aminophenol with in presence of sodium borohydride (NaBH 4 ). The conversion efficiency reaches almost 100% in 250 s with the quantity of Cu/Cu2O@NC as low as 5 mg. The outstanding H 2 production and organic pollutants removal are attributed to the oxygen vacancy. We expect that Cu/Cu2O@NC will find its way as a new resource for hydrogen energy as well as a promising material in water purification.
General Synthesis of Transition-Metal Oxide Hollow Nanospheres/Nitrogen-Doped Graphene Hybrids by Metal-Ammine Complex Chemistry for High-Performance Lithium-Ion Batteries.

Science.gov (United States)

Chen, Jiayuan; Wu, Xiaofeng; Gong, Yan; Wang, Pengfei; Li, Wenhui; Mo, Shengpeng; Peng, Shengpan; Tan, Qiangqiang; Chen, Yunfa

2018-02-09

We present a general and facile synthesis strategy, on the basis of metal-ammine complex chemistry, for synthesizing hollow transition-metal oxides (Co 3 O 4 , NiO, CuO-Cu 2 O, and ZnO)/nitrogen-doped graphene hybrids, potentially applied in high-performance lithium-ion batteries. The oxygen-containing functional groups of graphene oxide play a prerequisite role in the formation of hollow transition-metal oxides on graphene nanosheets, and a significant hollowing process occurs only when forming metal (Co 2+ , Ni 2+ , Cu 2+ , or Zn 2+ )-ammine complex ions. Moreover, the hollowing process is well correlated with the complexing capacity between metal ions and NH 3 molecules. The significant hollowing process occurs for strong metal-ammine complex ions including Co 2+ , Ni 2+ , Cu 2+ , and Zn 2+ ions, and no hollow structures formed for weak and/or noncomplex Mn 2+ and Fe 3+ ions. Simultaneously, this novel strategy can also achieve the direct doping of nitrogen atoms into the graphene framework. The electrochemical performance of two typical hollow Co 3 O 4 or NiO/nitrogen-doped graphene hybrids was evaluated by their use as anodic materials. It was demonstrated that these unique nanostructured hybrids, in contrast with the bare counterparts, solid transition-metal oxides/nitrogen-doped graphene hybrids, perform with significantly improved specific capacity, superior rate capability, and excellent capacity retention. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Nitrogen doping for adhesion improvement of DLC film deposited on Si substrate by Filtered Cathodic Vacuum Arc (FCVA) technique

Energy Technology Data Exchange (ETDEWEB)

Bootkul, D., E-mail: mo_duangkhae@hotmail.com [Department of General Science, Faculty of Science, Srinakharinwirot University, Bangkok 10110 (Thailand); Supsermpol, B.; Saenphinit, N. [Western Digital Company, Ayutthaya 13160 (Thailand); Aramwit, C. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50202 (Thailand); Intarasiri, S., E-mail: saweat@gmail.com [Science and Technology Research Institute, Chiang Mai University, Chiang Mai 50202 (Thailand)

2014-08-15

Diamond-like carbon (DLC) films have been used in many applications due to their attractive combination of properties including chemical inertness, corrosion protection, biocompatibility, high hardness, and low wear rates. However, they still have some limitations such as high internal stresses and low toughness which lead to poor adhesion of films. Synthesis of nitrogen-doped DLC (N-DLC) offers the possibility of overcoming these limitations. In this study, DLC films, namely tetrahedral amorphous carbon (ta-C) and nitrogen doped tetrahedral amorphous carbon (ta-C:N) were deposited on single crystalline Si wafer substrates using the Filtered Cathodic Vacuum Arc (FCVA) technique. Film characterizations were carried out by Raman spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM), triboindenter tester and nano-scratch tester. Measurement results showed that intentionally doping with nitrogen reduced the carbon sp{sup 3} content and increased the surface roughness in comparison with that of pure ta-C films. The hardness measurement confirmed the Raman and AFM analyses that adding nitrogen in ta-C films decreased the hardness, especially with high nitrogen content. However, the nano-scratch test revealed the increasing of the critical load with nitrogen. This work, then, extended its scope to investigate the properties of double-layer ta-C films which were composed of ta-C:N interlayer of various thickness around 10–30 nm and ta-C top-layer with thickness of around 80 nm. Microstructure characterization demonstrated that a ta-C:N interlayer gradually decreased the sp{sup 3} fraction in the films and increased film roughness whenever the ta-C:N interlayer thickness increased. In this structure, the tribological property in terms of adhesion to the Si substrate was significantly improved by about 20–90%, but the mechanical property in terms of hardness was gradually degraded by about 2–10%, compared to pure ta-C film, when the ta
Atomic layer deposition of high-mobility hydrogen-doped zinc oxide

NARCIS (Netherlands)

Macco, B.; Knoops, H.C.M.; Verheijen, M.A.; Beyer, W.; Creatore, M.; Kessels, W.M.M.

2017-01-01

In this work, atomic layer deposition (ALD) has been employed to prepare high-mobility H-doped zinc oxide (ZnO:H) films. Hydrogen doping was achieved by interleaving the ZnO ALD cycles with H2 plasma treatments. It has been shown that doping with H2 plasma offers key advantages over traditional
In situ one-step synthesis of hierarchical nitrogen-doped porous carbon for high-performance supercapacitors.

Science.gov (United States)

Jeon, Ju-Won; Sharma, Ronish; Meduri, Praveen; Arey, Bruce W; Schaef, Herbert T; Lutkenhaus, Jodie L; Lemmon, John P; Thallapally, Praveen K; Nandasiri, Manjula I; McGrail, Benard Peter; Nune, Satish K

2014-05-28

A hierarchically structured nitrogen-doped porous carbon is prepared from a nitrogen-containing isoreticular metal-organic framework (IRMOF-3) using a self-sacrificial templating method. IRMOF-3 itself provides the carbon and nitrogen content as well as the porous structure. For high carbonization temperatures (950 °C), the carbonized MOF required no further purification steps, thus eliminating the need for solvents or acid. Nitrogen content and surface area are easily controlled by the carbonization temperature. The nitrogen content decreases from 7 to 3.3 at % as carbonization temperature increases from 600 to 950 °C. There is a distinct trade-off between nitrogen content, porosity, and defects in the carbon structure. Carbonized IRMOFs are evaluated as supercapacitor electrodes. For a carbonization temperature of 950 °C, the nitrogen-doped porous carbon has an exceptionally high capacitance of 239 F g(-1). In comparison, an analogous nitrogen-free carbon bears a low capacitance of 24 F g(-1), demonstrating the importance of nitrogen dopants in the charge storage process. The route is scalable in that multi-gram quantities of nitrogen-doped porous carbons are easily produced.
Remarkable activity of nitrogen-doped hollow carbon spheres encapsulated Cu on synthesis of dimethyl carbonate: Role of effective nitrogen

Science.gov (United States)

Li, Haixia; Zhao, Jinxian; Shi, Ruina; Hao, Panpan; Liu, Shusen; Li, Zhong; Ren, Jun

2018-04-01

A critical aspect in the improvement of the catalytic performance of Cu-based catalysts for the synthesis of dimethyl carbonate (DMC) is the development of an appropriate support. In this work, nitrogen-doped hollow carbon spheres (NHCSs), with 240 nm average diameter, 17 nm shell thickness, uniform mesoporous structure and a specific surface area of 611 m2 g-1, were prepared via a two-step Stӧber method. By varying the quantity of nitrogen-containing phenols used in the preparation it has been possible to control the nitrogen content and, consequently, the sphericity of the NHCSs. It was found that perfect spheres were obtained for nitrogen contents below 5.4 wt.%. The catalysts (Cu@NHCSs) were prepared by the hydrothermal impregnation method. The catalytic activity towards DMC synthesis was notably enhanced due to the immobilization effect on Cu particles and the enhanced electron transfer effect exercised by the effective nitrogen species, including pyridinic-N and graphitic-N. When the average size of the copper nanoparticles was 7.4 nm and the nitrogen content was 4.0 wt.%, the values of space-time yield of DMC and of turnover frequency (TOF) reached 1528 mg/(g h) and 11.0 h-1, respectively. The TOF value of Cu@NHCSs was 6 times higher than non-doped Cu@Carbon (2.1 h-1). The present work introduces the potential application of nitrogen-doped carbon materials and presents a novel procedure for the preparation of catalysts for DMC synthesis.
A comparison study of rhodamine B photodegradation over nitrogen-doped lamellar niobic acid and titanic acid under visible-light irradiation.

Science.gov (United States)

Li, Xiukai; Kikugawa, Naoki; Ye, Jinhua

2009-01-01

A solid-state reaction method with urea as a nitrogen precursor was used to prepare nitrogen-doped lamellar niobic and titanic solid acids (i.e., HNb(3)O(8) and H(2)Ti(4)O(9)) with different acidities for visible-light photocatalysis. The photocatalytic activities of the nitrogen-doped solid acids were evaluated for rhodamine B (RhB) degradation and the results were compared with those obtained over the corresponding nitrogen-doped potassium salts. Techniques such as XRD, BET, SEM, X-ray photoelectron spectroscopy, and UV-visible diffuse reflectance spectroscopy were adopted to explore the nature of the materials as well as the characteristics of the doped nitrogen species. It was found that the intercalation of the urea precursor helped to stabilize the layered structures of both lamellar solid acids and enabled easier nitrogen doping. The effects of urea intercalation were more significant for the more acidic HNb(3)O(8) sample than for the less acidic H(2)Ti(4)O(9). Compared with the nitrogen-doped KNb(3)O(8) and K(2)Ti(4)O(9) samples, the nitrogen-doped HNb(3)O(8) and H(2)Ti(4)O(9) solid acids absorb more visible light and exhibit a superior activity for RhB photodegradation under visible-light irradiation. The nitrogen-doped HNb(3)O(8) sample performed the best among all the samples. The results of the current study suggest that the protonic acidity of the lamellar solid-acid sample is a key factor that influences nitrogen doping and the resultant visible-light photocatalysis.
A facile fabrication of nitrogen-doped electrospun In2O3 nanofibers with improved visible-light photocatalytic activity

Science.gov (United States)

Lu, Na; Shao, Changlu; Li, Xinghua; Miao, Fujun; Wang, Kexin; Liu, Yichun

2017-01-01

Semiconductor photocatalysis demonstrates to be an effective approach for eliminating most types of environment contaminants and for producing hydrogen. Herein, a facile synthesis route combining electrospinning technique and thermal treatment method under NH3 atmosphere has been presented as a straightforward protocol for the fabrication of nitrogen-doped In2O3 (N-In2O3) nanofibers, the nitrogen content of which can be well controlled by adjusting the annealing temperature. Photocatalytic tests show that the N-In2O3 nanofibers demonstrate an improved degradation rate of Rhodamine B (RB) compared with pure In2O3 nanofibers under visible-light irradiation. This can be attributed to the nitrogen atom introducing at interstitial sites as well as the generation of oxygen vacancy on the surface of In2O3 nanofibers, resulting in the enhanced utilization of visible light for the N-In2O3 nanofibers. Furthermore, the obtained N-In2O3 nanofibers with the advantage of ultra-long one-dimensional nanostructures can be recycled several times by facile sedimentation and hence present almost no decrease in photocatalytic activity indicative of a well regeneration capability. Therefore, the as-fabricated nitrogen-doped In2O3 nanofibers as a promising photocatalyst present good photocatalytic degradation of organic pollutant in waste water for practical application.
Combined effect of nitrogen doping and nanosteps on microcrystalline diamond films for improvement of field emission

International Nuclear Information System (INIS)

Mengui, U.A.; Campos, R.A.; Alves, K.A.; Antunes, E.F.; Hamanaka, M.H.M.O.; Corat, E.J.; Baldan, M.R.

2015-01-01

Highlights: • Hot filament chemical vapor deposition using methane, hydrogen and a solution of urea in methanol produced nitrogen-doped diamond films. • Diamonds had the grain morphology changed for long growth time (28 h), and the nitrogen doping were evaluated by Raman spectroscopy. • Field emission characterization shows a decrease up to 70% in threshold field, related to reference diamond layer. - Abstract: Nitrogen-doped microcrystalline diamond (N-MCD) films were grown on Si substrates using a hot filament reactor with methanol solution of urea as N source. Electrostatic self-assembly seeding of nanocrystalline diamond were used to obtain continuous and uniform films. Simultaneous changes in grains morphology and work function of diamond by nitrogen doping decreased the threshold field and the angular coefficient of Fowler–Nordhein plots. The field emission properties of our N-MCD films are comparable to carbon nanotube films
Combined effect of nitrogen doping and nanosteps on microcrystalline diamond films for improvement of field emission

Energy Technology Data Exchange (ETDEWEB)

Mengui, U.A., E-mail: ursulamengui@gmail.com [INPE – Instituto Nacional de Pesquisas Espaciais Laboratório Associado de Sensores e Materiais – LAS, Av. dos Astronautas 1758, CP 515, CEP 12.245-970, São José dos Campos, SP (Brazil); Campos, R.A.; Alves, K.A.; Antunes, E.F. [INPE – Instituto Nacional de Pesquisas Espaciais Laboratório Associado de Sensores e Materiais – LAS, Av. dos Astronautas 1758, CP 515, CEP 12.245-970, São José dos Campos, SP (Brazil); Hamanaka, M.H.M.O. [Centro de Tecnologia da Informação Renato Archer, Divisão de Superfícies de Interação e Displays, Rodovia D. Pedro I (SP 65) km 143.6, CP 6162, CEP 13089-500, Campinas, SP (Brazil); Corat, E.J.; Baldan, M.R. [INPE – Instituto Nacional de Pesquisas Espaciais Laboratório Associado de Sensores e Materiais – LAS, Av. dos Astronautas 1758, CP 515, CEP 12.245-970, São José dos Campos, SP (Brazil)

2015-04-15

Highlights: • Hot filament chemical vapor deposition using methane, hydrogen and a solution of urea in methanol produced nitrogen-doped diamond films. • Diamonds had the grain morphology changed for long growth time (28 h), and the nitrogen doping were evaluated by Raman spectroscopy. • Field emission characterization shows a decrease up to 70% in threshold field, related to reference diamond layer. - Abstract: Nitrogen-doped microcrystalline diamond (N-MCD) films were grown on Si substrates using a hot filament reactor with methanol solution of urea as N source. Electrostatic self-assembly seeding of nanocrystalline diamond were used to obtain continuous and uniform films. Simultaneous changes in grains morphology and work function of diamond by nitrogen doping decreased the threshold field and the angular coefficient of Fowler–Nordhein plots. The field emission properties of our N-MCD films are comparable to carbon nanotube films.
Self-assembled nitrogen-doped fullerenes and their catalysis for fuel cell and rechargeable metal-air battery applications.

Science.gov (United States)

Noh, Seung Hyo; Kwon, Choah; Hwang, Jeemin; Ohsaka, Takeo; Kim, Beom-Jun; Kim, Tae-Young; Yoon, Young-Gi; Chen, Zhongwei; Seo, Min Ho; Han, Byungchan

2017-06-08

In this study, we report self-assembled nitrogen-doped fullerenes (N-fullerene) as non-precious catalysts, which are active for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), and thus applicable for energy conversion and storage devices such as fuel cells and metal-air battery systems. We screen the best N-fullerene catalyst at the nitrogen doping level of 10 at%, not at the previously known doping level of 5 or 20 at% for graphene. We identify that the compressive surface strain induced by doped nitrogen plays a key role in the fine-tuning of catalytic activity.
Influence of nitrogen dopants on N-doped TiO2 electrodes and their applications in dye-sensitized solar cells

International Nuclear Information System (INIS)

Guo Wei; Shen Yihua; Boschloo, Gerrit; Hagfeldt, Anders; Ma Tingli

2011-01-01

Highlights: → Three different types of nanocrystalline N-doped TiO 2 synthesized by several nitrogen dopants. → N-doped DSCs achieves a high conversion efficiency of 8.32%. → Ammonia acts as good nitrogen dopants. → Enhanced photocurrent of ca. 36% in N-doped DSCs. → Less charge are needed to get a high open-circuit voltage in N-doped films. - Abstract: Three different types of nanocrystalline, N-doped TiO 2 electrodes were synthesized using several nitrogen dopants through wet methods. The obtained nanocrystalline, N-doped TiO 2 electrodes possessed different crystallite sizes, surface areas, and N-doping amounts. Characterizations were performed to reveal the nitrogen-doping processes for the wet methods using ammonia, urea, and triethylamine as the nitrogen dopants. Additionally, a high conversion efficiency of 8.32% was achieved by the dye-sensitized solar cells, based on the N-doped TiO 2 electrodes. For instance, in comparison with the commercial P25 (5.76%) and pure anatase TiO 2 electrodes (7.14%), significant improvements (44% and 17%, respectively) in the efficiencies were obtained. The findings also indicated that the ammonia nitrogen dopant was more efficient than other two nitrogen dopants. The electron transports, electron lifetimes, and charge recombination in the dye-sensitized N-doped TiO 2 solar cells also differed from those in the pure TiO 2 -based dye-sensitized solar cells (DSCs). Specifically, an enhanced photocurrent of ca. 36% in N-doped DSCs resulted from the synergistic effects of the high dye uptake and the efficient electron transport. Moreover, the relationship between charge and voltage revealed that less charge was needed to get a high open-circuit voltage in the N-doping films.
The influence of oxygen and nitrogen doping on GeSbTe phase-change optical recording media properties

Energy Technology Data Exchange (ETDEWEB)

Dimitrov, D.; Shieh, H.-P.D

2004-03-15

Nitrogen and oxygen doped and co-doped GeSbTe (GST) films for phase-change optical recording are investigated. It is found that the crystallization temperature increased as well as the crystalline microstructure refined by doping. The carrier-to-noise ratio (CNR) and erasability of phase-change optical disks are improved being up to 52 and 35 dB, respectively, by using an appropriate nitrogen doping or co-doping concentration in the recording layer. Optical disks with co-doped recording layer are found to be superior in the recording characteristics then the single doped recording layer disks.
Thermoluminescence properties of undoped and nitrogen-doped CVD diamond exposed to gamma radiation

International Nuclear Information System (INIS)

Barboza-Flores, M.; Gastelum, S.; Cruz-Zaragoza, E.; Melendrez, R.; Chernov, V.; Pedroza-Montero, M.; Favalli, A.

2008-01-01

It is known that the thermoluminescence (TL) performance of CVD diamond depends on the impurity concentration and doping materials introduced during growing. We report on the TL properties of undoped and 750 ppm nitrogen-doped CVD diamond grown on (0 0 1) silicon substrate. The samples were exposed to gamma radiation from a Gammacell 200 Nordion irradiator in the 10-500 Gy dose range at 627 mGy/min dose rate. The nitrogen-doped CVD diamond sample exhibited a TL glow curve peaked around 537 K and a small shoulder about 411 K and a linear dose behavior in the 10-60 Gy dose range. In contrast, the undoped specimen showed a 591 K peaked TL glow curve and linear dose response for 10-100 Gy doses. However, both samples displayed a non-linear dose response for doses higher than 100 Gy. The doping effects seem to cause a higher TL efficiency, which may be attributed to the differences in the diamond bonding and amorphous carbon on the CVD samples as well as to the presence of nitrogen. In addition, the nitrogen content may produce some structural and morphological surface effects, which may account for the distinctive TL features and dose response of the diamond samples
Rapid synthesis of nitrogen doped titania with mixed crystal lattice via microwave-assisted hydrothermal method

International Nuclear Information System (INIS)

Zhang Peilin; Liu Bin; Yin Shu; Wang Yuhua; Petrykin, Valery; Kakihana, Masato; Sato, Tsugio

2009-01-01

A microwave-assisted hydrothermal method was employed to synthesize nitrogen doped titania nanoparticles. Due to the high heating efficiency of microwave, rapid synthesis could be achieved in comparison with the conventional oven. Mixed crystal lattice was found existing in the obtained product, and the phase transformation behaviour under calcination was studied by XRD measurement together with Raman spectroscopy in details. The obtained nitrogen doped titania showed high specific surface area, about 300 m 2 g -1 . Photocatalytic activity in destructing NO x gas by the prepared sample exceeded that of commercial titania (P 25) or nitrogen doped titania synthesized by conventional hydrothermal method, under both visible-light and ultraviolet-light irradiation.
Doping Nitrogen in InGaZnO Thin Film Transistor with Double Layer Channel Structure.

Science.gov (United States)

Chang, Sheng-Po; Shan, Deng

2018-04-01

This paper presents the electrical characteristics of doping nitrogen in an amorphous InGaZnO thin film transistor. The IGZO:N film, which acted as a channel layer, was deposited using RF sputtering with a nitrogen and argon gas mixture at room temperature. The optimized parameters of the IGZO:N/IGZO TFT are as follows: threshold voltage is 0.5 V, field effect mobility is 14.34 cm2V-1S-1. The on/off current ratio is 106 and subthreshold swing is 1.48 V/decade. The positive gate bias stress stability of InGaZnO doping with nitrogen shows improvement compared to doping with oxygen.

A co-confined carbonization approach to aligned nitrogen-doped mesoporous carbon nanofibers and its application as an adsorbent

International Nuclear Information System (INIS)

Chen, Aibing; Liu, Chao; Yu, Yifeng; Hu, Yongqi; Lv, Haijun; Zhang, Yue; Shen, Shufeng; Zhang, Jian

2014-01-01

Highlights: • MCNFs were synthesized by a co-confined carbonization method. • The diameter size of MCNFs with bimodal mesoporous structure can be modulated. • The obtained MCNFs manifest better adsorption capacity for SO 2 , CO 2 and Cd 2+ . - Abstract: Nitrogen-doped carbon nanofibers (MCNFs) with an aligned mesoporous structure were synthesized by a co-confined carbonization method using anodic aluminum oxide (AAO) membrane and tetraethylorthosilicate (TEOS) as co-confined templates and ionic liquids as the precursor. The as-synthesized MCNFs with the diameter of 80–120 nm possessed a bulk nitrogen content of 5.3 wt% and bimodal mesoporous structure. The nitrogen atoms were mostly bound to the graphitic network in two forms, i.e. pyridinic and pyrrolic nitrogen, providing adsorption sites for acidic gases like SO 2 and CO 2 . Cyclic experiments revealed a considerable stability of MCNFs over 20 runs of SO 2 adsorption and 15 runs for CO 2 adsorption. The MCNFs also have a preferable adsorption performance for Cd 2+
Thermal stability of atom configurations around Er atoms doped in InP by OMVPE

International Nuclear Information System (INIS)

Ofuchi, Hironori; Ito, Takashi; Kawamoto, Takeshi; Tabuchi, Masao; Fujiwara, Yasufumi; Takeda, Yoshikazu

1999-01-01

It has been found that there is a threshold growth temperature between 550 deg C and 580 deg C for the change of local structure around Er atoms in InP doped Er atoms grown by organometallic vapor phase epitaxy (OMVPE). To understand whether the structure change is induced at the growing surface or during the growth as an in situ annealing, the thermal stability of the local structures around the Er atoms doped in InP by the OMVPE at 530 deg C has been investigated by the extended X-ray absorption fine structure (EXAFS). The EXAFS analysis revealed that the local structure around the Er atoms, which existed substitutionally on In sites in the InP lattice, was stable against the post-growth annealing even for 1 h at 650 deg C. Therefore, it is concluded that the local structures are formed on the growth front, and not in the volume of InP by thermal annealing during or after the growth. (author)
Phosphorus, and nitrogen co-doped carbon dots as a fluorescent probe for real-time measurement of reactive oxygen and nitrogen species inside macrophages.

Science.gov (United States)

Gong, Yunqian; Yu, Bin; Yang, Wen; Zhang, Xiaoling

2016-05-15

Phosphorus and nitrogen doped carbon dots (PN-CDs) were conveniently prepared by carbonization of adenosine-5'-triphosphate using a hydrothermal treatment. The PN-CDs with P/C atomic ratio of ca. 9.2/100 emit blue luminescence with high quantum yields of up to 23.5%. The PN-CDs were used as a novel sensing platform for live cell imaging of reactive oxygen species (ROS) and reactive nitrogen species (RNS), including ClO(-), ONOO(-), and NO in macrophages. The nanosensor design is based on our new finding that the strong fluorescence of the PN-CDs can be sensitively and selectively quenched by ROS and RNS both in vitro and in vivo. These results reveal that the PN-CDs can serve as a sensitive sensor for rapid imaging of ROS and RNS signaling with high selectivity and contrast. Copyright © 2016 Elsevier B.V. All rights reserved.
Facile Synthesis of Nitrogen Doped Graphene Oxide from Graphite Flakes and Powders: A Comparison of Their Surface Chemistry.

Science.gov (United States)

Yokwana, Kholiswa; Ray, Sekhar C; Khenfouch, Mohammad; Kuvarega, Alex T; Mamba, Bhekie B; Mhlanga, Sabelo D; Nxumalo, Edward N

2018-08-01

Nitrogen-doped graphene oxide (NGO) nanosheets were prepared via a facile one-pot modified Hummer's approach at low temperatures using graphite powder and flakes as starting materials in the presence of a nitrogen precursor. It was found that the morphology, structure, composition and surface chemistry of the NGO nanosheets depended on the nature of the graphite precursor used. GO nanosheets doped with nitrogen atoms exhibited a unique structure with few thin layers and wrinkled sheets, high porosity and structural defects. NGO sheets made from graphite powder (NGOp) exhibited excellent thermal stability and remarkably high surface area (up to 240.53 m2 ·g-1) compared to NGO sheets made from graphite flakes (NGOf) which degraded at low temperatures and had an average surface area of 24.70 m2 ·g-1. NGOf sheets had a size range of 850 to 2200 nm while NGOp sheets demonstrated obviously small sizes (460-1600 nm) even when exposed to different pH conditions. The NGO nanosheets exhibited negatively charged surfaces in a wide pH range (1 to 12) and were found to be stable above pH 6. In addition, graphite flakes were found to be more suitable for the production of NGO as they produced high N-doping levels (0.65 to 1.29 at.%) compared to graphite powders (0.30 to 0.35 at.%). This study further demonstrates that by adjusting the amount of N source in the host GO, one can tailor its thermal stability, surface morphology, surface chemistry and surface area.
Hierarchical nitrogen doped bismuth niobate architectures: Controllable synthesis and excellent photocatalytic activity

International Nuclear Information System (INIS)

Hou, Jungang; Cao, Rui; Wang, Zheng; Jiao, Shuqiang; Zhu, Hongmin

2012-01-01

Graphical abstract: Efficient visible-light-driven photocatalysts of peony-like nitrogen doped Bi 3 NbO 7 hierarchical architectures and silver-layered Bi 3 NbO 7−x Nx heterostructures were successfully synthesized in this discovery. Highlights: ► N-Bi 3 NbO 7 architectures were synthesized via two-step hydrothermal process. ► Electronic structure calculations indicated that N replaced O in samples. ► Growth mechanism is proposed for transformation of nanoparticles to microflowers. ► Excellent activities of N-Bi 3 NbO 7 architectures were obtained for degradation. ► Enhanced photocatalytic performance was observed for Ag/N-Bi 3 NbO 7 architectures. - Abstract: Nitrogen doped bismuth niobate (N-Bi 3 NbO 7 ) hierarchical architectures were synthesized via a facile two-step hydrothermal process. XRD patterns revealed that the defect fluorite-type crystal structure of Bi 3 NbO 7 remained intact upon nitrogen doping. Electron microscopy showed the N-Bi 3 NbO 7 architecture has a unique peony-like spherical superstructure composed of numerous nanosheets. UV–vis spectra indicated that nitrogen doping in the compound results in a red-shift of the absorption edge from 450 nm to 470 nm. XPS indicated that [Bi/Nb]-N bonds were formed by inducing nitrogen to replace a small amount of oxygen in Bi 3 NbO 7−x N x , which is explained by electronic structure calculations including energy band and density of states. Based on observations of architectures formation, a possible growth mechanism was proposed to explain the transformation of polyhedral-like nanoparticles to peony-like microflowers via an Ostwald riping mechanism followed by self-assembly. The N-Bi 3 NbO 7 architectures due to the large specific surface area and nitrogen doping exhibited higher photocatalytic activities in the decomposition of organic pollutant under visible-light irradiation than Bi 3 NbO 7 nanoparticles. Furthermore, an enhanced photocatalytic performance was also observed for Ag
Plasmon excitations in doped square-lattice atomic clusters

Science.gov (United States)

Wang, Yaxin; Yu, Ya-Bin

2017-12-01

Employing the tight-binding model, we theoretically study the properties of the plasmon excitations in doped square-lattice atomic clusters. The results show that the dopant atoms would blur the absorption spectra, and give rise to extra plasmon resonant peaks as reported in the literature; however, our calculated external-field induced oscillating charge density shows that no obvious evidences indicate the so-called local mode of plasmon appearing in two-dimensional-doped atomic clusters, but the dopants may change the symmetry of the charge distribution. Furthermore, we show that the disorder of the energy level due to dopant makes the absorption spectrum has a red- or blue-shift, which depends on the position of impurities; disorder of hopping due to dopant makes a blue- or red-shift, a larger (smaller) hopping gives a blue-shift (red-shift); and a larger (smaller) host-dopant and dopant-dopant intersite coulomb repulsion induces a blue-shift (red-shift).
Catalytic activity of Pd-doped Cu nanoparticles for hydrogenation as a single-atom-alloy catalyst.

Science.gov (United States)

Cao, Xinrui; Fu, Qiang; Luo, Yi

2014-05-14

The single atom alloy of extended surfaces is known to provide remarkably enhanced catalytic performance toward heterogeneous hydrogenation. Here we demonstrate from first principles calculations that this approach can be extended to nanostructures, such as bimetallic nanoparticles. The catalytic properties of the single-Pd-doped Cu55 nanoparticles have been systemically examined for H2 dissociation as well as H atom adsorption and diffusion, following the concept of single atom alloy. It is found that doping a single Pd atom at the edge site of the Cu55 shell can considerably reduce the activation energy of H2 dissociation, while the single Pd atom doped at the top site or in the inner layers is much less effective. The H atom adsorption on Cu55 is slightly stronger than that on the Cu(111) surface; however, a larger nanoparticle that contains 147 atoms could effectively recover the weak binding of the H atoms. We have also investigated the H atom diffusion on the 55-atom nanoparticle and found that spillover of the produced H atoms could be a feasible process due to the low diffusion barriers. Our results have demonstrated that facile H2 dissociation and weak H atom adsorption could be combined at the nanoscale. Moreover, the effects of doping one more Pd atom on the H2 dissociation and H atom adsorption have also been investigated. We have found that both the doping Pd atoms in the most stable configuration could independently exhibit their catalytic activity, behaving as two single-atom-alloy catalysts.
Raman spectroscopy of boron-doped single-layer graphene.

Science.gov (United States)

Kim, Yoong Ahm; Fujisawa, Kazunori; Muramatsu, Hiroyuki; Hayashi, Takuya; Endo, Morinobu; Fujimori, Toshihiko; Kaneko, Katsumi; Terrones, Mauricio; Behrends, Jan; Eckmann, Axel; Casiraghi, Cinzia; Novoselov, Kostya S; Saito, Riichiro; Dresselhaus, Mildred S

2012-07-24

The introduction of foreign atoms, such as nitrogen, into the hexagonal network of an sp(2)-hybridized carbon atom monolayer has been demonstrated and constitutes an effective tool for tailoring the intrinsic properties of graphene. Here, we report that boron atoms can be efficiently substituted for carbon in graphene. Single-layer graphene substitutionally doped with boron was prepared by the mechanical exfoliation of boron-doped graphite. X-ray photoelectron spectroscopy demonstrated that the amount of substitutional boron in graphite was ~0.22 atom %. Raman spectroscopy demonstrated that the boron atoms were spaced 4.76 nm apart in single-layer graphene. The 7-fold higher intensity of the D-band when compared to the G-band was explained by the elastically scattered photoexcited electrons by boron atoms before emitting a phonon. The frequency of the G-band in single-layer substitutionally boron-doped graphene was unchanged, which could be explained by the p-type boron doping (stiffening) counteracting the tensile strain effect of the larger carbon-boron bond length (softening). Boron-doped graphene appears to be a useful tool for engineering the physical and chemical properties of graphene.
Improvement in switching characteristics and long-term stability of Zn-O-N thin-film transistors by silicon doping

Directory of Open Access Journals (Sweden)

Hiroshi Tsuji

2017-06-01

Full Text Available The effects of silicon doping on the properties of Zn-O-N (ZnON films and on the device characteristics of ZnON thin-film transistors (TFTs were investigated by co-sputtering silicon and zinc targets. Silicon doping was effective at decreasing the carrier concentration in ZnON films; therefore, the conductivity of the films can be controlled by the addition of a small amount of silicon. Doped silicon atoms also form bonds with nitrogen atoms, which suppresses nitrogen desorption from the films. Furthermore, Si-doped ZnON-TFTs are demonstrated to exhibit less negative threshold voltages, smaller subthreshold swings, and better long-term stability than non-doped ZnON-TFTs.
Tuning the Photoluminescence of Graphene Quantum Dots by Photochemical Doping with Nitrogen

Directory of Open Access Journals (Sweden)

Xiaofen Xu

2017-11-01

Full Text Available Nitrogen-doped graphene quantum dots (NGQDs were synthesized by irradiating graphene quantum dots (GQDs in an NH3 atmosphere. The photoluminescence (PL properties of the GQDs and the NGQDs samples were investigated. Compared with GQDs, a clear PL blue-shift of NGQDs could be achieved by regulating the irradiating time. The NGQDs obtained by irradiation of GQDs for 70 min had a high N content of 15.34 at % and a PL blue-shift of about 47 nm. This may be due to the fact that photochemical doping of GQDs with nitrogen can significantly enhance the contents of pyridine-like nitrogen, and also effectively decrease the contents of oxygen functional groups of NGQDs, thus leading to the observed obvious PL blue-shift.
Application of nitrogen-doped TiO{sub 2} nano-tubes in dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Tran, Vy Anh; Truong, Trieu Thinh; Phan, Thu Anh Pham; Nguyen, Trang Ngoc [Faculty of Chemistry, University of Science, Vietnam National University, Ho Chi Minh City (Viet Nam); Huynh, Tuan Van [Faculty of Physics and Engineering Physics, University of Science, Vietnam National University, Ho Chi Minh City (Viet Nam); Agresti, Antonio; Pescetelli, Sara [CHOSE (Centre for Hybrid and Organic Solar Energy), Department of Electronic Engineering, University of Rome Tor Vergata (Italy); Le, Tien Khoa [Faculty of Chemistry, University of Science, Vietnam National University, Ho Chi Minh City (Viet Nam); Di Carlo, Aldo [CHOSE (Centre for Hybrid and Organic Solar Energy), Department of Electronic Engineering, University of Rome Tor Vergata (Italy); Lund, Torben [Department of Science and Environment, Roskilde University, DK-4000 (Denmark); Le, So-Nhu [Faculty of Chemistry, University of Science, Vietnam National University, Ho Chi Minh City (Viet Nam); Nguyen, Phuong Tuyet, E-mail: ngtuyetphuong@gmail.com [Faculty of Chemistry, University of Science, Vietnam National University, Ho Chi Minh City (Viet Nam)

2017-03-31

Highlights: • N-doped TiO{sub 2} nanotubes are synthesized by alkaline hydrothermal and reflux method. • Formation of TiO{sub 2} nanotube morphology and anatase phase is shown by TEM, XRD, Raman. • Coordination of NH{sub 4}{sup +} via Ti−O−NH{sub 4}{sup +} or H{sub 4}N{sup +}−Ti−O bonds is indicated by FT-IR and XPS. • Blocking effect of N-doped toward electron transfer on TiO{sub 2} anode is studied by CV. • N-doped TiO{sub 2} improved DSC performance up to 30–40% mainly due to an increase in J{sub sc}. - Abstract: Our research aimed to improve the overall energy conversion efficiency of DSCs by applying nitrogen-doped TiO{sub 2} nano-tubes (N-TNT) for the preparation of DSCs photo-anodes. The none-doped TiO{sub 2} nano-tubes (TNTs) were synthesized by alkaline hydrothermal treatment of Degussa P25 TiO{sub 2} particles in 10 M NaOH. The nano-tubes were N-doped by reflux in various concentrations of NH{sub 4}NO{sub 3}. The effects of nitrogen doping on the structure, morphology, and crystallography of N-TNT were analyzed by transmission electron microscopy (TEM), infrared spectroscopy (IR), Raman spectroscopy, and X-ray photoelectron spectra (XPS). DSCs fabricated with doped N-TNT and TNT was characterized by J-V measurements. Results showed that nitrogen doping significantly enhanced the efficiency of N-TNT cells, reaching the optimum value (η = 7.36%) with 2 M nitrogen dopant, compared to η = 4.75% of TNT cells. The high efficiency of the N-TNT cells was attributed to increased current density due to the reduction of dark current in the DSCs.
High capacity and high rate capability of nitrogen-doped porous hollow carbon spheres for capacitive deionization

International Nuclear Information System (INIS)

Zhao, Shanshan; Yan, Tingting; Wang, Hui; Chen, Guorong; Huang, Lei; Zhang, Jianping; Shi, Liyi; Zhang, Dengsong

2016-01-01

Graphical abstract: - Highlights: • The nitrogen-doped porous hollow carbon spheres were prepared. • The obtained materials have a good capacitive deionization performance. • The electrodes show high salt adsorption rate and good regeneration performance. - Abstract: In this work, nitrogen-doped porous hollow carbon spheres (N-PHCS) were well prepared by using polystyrene (PS) spheres as hard templates and dopamine hydrochloride as carbon and nitrogen sources. Field emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images demonstrate that the N-PHCS have a uniform, spherical and hollow structure. Nitrogen adsorption–desorption analysis shows that the N-PHCS have a high specific area of 512 m 2 /g. X-ray photoelectron spectroscopy result reveals that the nitrogen doping amount is 2.92%. The hollow and porous structure and effective nitrogen doping can contribute to large accessible surface area, efficient ion transport and good conductivity. In the electrochemical tests, we can conclude that the N-PHCS have a high specific capacitance value, a good stability and low inner resistance. The N-PHCS electrodes present a high salt adsorption capacity of 12.95 mg/g at a cell voltage of 1.4 V with a flow rate of 40 mL/min in a 500 mg/L NaCl aqueous solution. Moreover, the N-PHCS electrodes show high salt adsorption rate and good regeneration performance in the CDI process. With high surface specific area and effective nitrogen doping, the N-PHCS is promising to the CDI and other electrochemical applications.
High capacity and high rate capability of nitrogen-doped porous hollow carbon spheres for capacitive deionization

Energy Technology Data Exchange (ETDEWEB)

Zhao, Shanshan; Yan, Tingting; Wang, Hui; Chen, Guorong; Huang, Lei; Zhang, Jianping; Shi, Liyi; Zhang, Dengsong, E-mail: dszhang@shu.edu.cn

2016-04-30

Graphical abstract: - Highlights: • The nitrogen-doped porous hollow carbon spheres were prepared. • The obtained materials have a good capacitive deionization performance. • The electrodes show high salt adsorption rate and good regeneration performance. - Abstract: In this work, nitrogen-doped porous hollow carbon spheres (N-PHCS) were well prepared by using polystyrene (PS) spheres as hard templates and dopamine hydrochloride as carbon and nitrogen sources. Field emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images demonstrate that the N-PHCS have a uniform, spherical and hollow structure. Nitrogen adsorption–desorption analysis shows that the N-PHCS have a high specific area of 512 m{sup 2}/g. X-ray photoelectron spectroscopy result reveals that the nitrogen doping amount is 2.92%. The hollow and porous structure and effective nitrogen doping can contribute to large accessible surface area, efficient ion transport and good conductivity. In the electrochemical tests, we can conclude that the N-PHCS have a high specific capacitance value, a good stability and low inner resistance. The N-PHCS electrodes present a high salt adsorption capacity of 12.95 mg/g at a cell voltage of 1.4 V with a flow rate of 40 mL/min in a 500 mg/L NaCl aqueous solution. Moreover, the N-PHCS electrodes show high salt adsorption rate and good regeneration performance in the CDI process. With high surface specific area and effective nitrogen doping, the N-PHCS is promising to the CDI and other electrochemical applications.
Nitrogen-doped carbon capsules via poly(ionic liquid)-based layer-by-layer assembly.

Science.gov (United States)

Zhao, Qiang; Fellinger, Tim-Patrick; Antonietti, Markus; Yuan, Jiayin

2012-07-13

Layer-by-layer (LbL) assembly technique is applied for the first time for the preparation of nitrogen-doped carbon capsules. This approach uses colloid silica as template and two polymeric deposition components, that is, poly(ammonium acrylate) and a poly (ionic liquid) poly(3-cyanomethyl-1-vinylimidazolium bromide), which acts as both the carbon precursor and nitrogen source. Nitrogen-doped carbon capsules are prepared successfully by polymer wrapping, subsequent carbonization and template removal. The as-synthesized carbon capsules contain ≈7 wt% of nitrogen and have a structured specific surface area of 423 m(2) g(-1). Their application as supercapacitor has been briefly introduced. This work proves that LbL assembly methodology is available for preparing carbon structures of complex morphology. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Atomic nitrogen encapsulated in fullerenes: realization of a chemical Faraday cage

International Nuclear Information System (INIS)

Lips, K.

2000-01-01

Fullerenes, C 60 and C 70 , are ideal containers for atomic nitrogen. We will show by electron paramagnetic resonance (EPR) experiments that nitrogen in C 60 keeps its atomic ground state configuration and resides in the center of the cage. This is the first time that atomic nitrogen is stabilized at ambient conditions. The inert shell of the fullerene protects the highly reactive nitrogen from undergoing chemical reactions with the surroundings. The fullerene cage is the chemical analogue of the Faraday cage in case of electrical fields, i.e. it shields off the chemical reactivity. As for the free nitrogen atom, the spins of the three p-electrons of nitrogen in C 60 are parallel (S = 3/2) and the atom has spherical symmetry. Due to the center position of nitrogen in C 60 , extremely sharp EPR lines are observed. This reflects the absence of a strong host-guest interaction and shows that the individuality of nitrogen in the fullerenes is preserved. Further evidence for the almost interaction-free suspension of nitrogen in the fullerene cages is provided by g-factor measurements. These investigations show that magnetic shielding of the host molecules can account for the observed differences between N rate at C 60 and N rate at C 70 . The fullerene cage can be chemically modified without destroying the endohedral complex. The chemical modifications change the symmetry of the molecule which is observed through an additional fine structure in the EPR spectrum. Influences of the modifications on the stability of N rate at C 60 will be discussed. (orig.)
Synthesis of nitrogen-doped and amino acid-functionalized graphene quantum dots from glycine, and their application to the fluorometric determination of ferric ion

International Nuclear Information System (INIS)

Li, Linbo; Li, Lin; Wang, Chao; Liu, Kangyu; Zhu, Ruohua; Qiang, Hong; Lin, Yuqing

2015-01-01

We report on a single-step thermolysis strategy to prepare highly luminescent nitrogen-doped and amino acid-functionalized graphene quantum dots (NA-GQDs) by using glycine as both carbon and nitrogen source. The NA-GQDs display an excitation wavelength-dependent fluorescence with maximum excitation and emission wavelengths of 380 and 450 nm, respectively, and a quantum yield of ∼16 %. Fluorescence is quenched by Fe(III) and Hg(II), and the effect was used to develop a method for the determination of Fe(III). Quenching by Fe(III) is attributed to its higher thermodynamic affinity (compared to other transition-metal ions) for the ligands on the GQDs in which nitrogen atoms mainly act as the chelating atoms. A linear relationship was observed between fluorescence intensity and the concentration of Fe(III) over the 0.5 μM to 0.5 mM range. The detection limit is 0.1 μM. (author)
Electronic and magnetic properties of nonmetal atoms doped blue phosphorene: First-principles study

Energy Technology Data Exchange (ETDEWEB)

Zheng, Huiling; Yang, Hui [Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), Department of Physics, Jilin University, Changchun 130012 (China); Wang, Hongxia [College of Mathematics, Physics and Information Science, Zhejiang Ocean University, Zhoushan 316000 (China); Du, Xiaobo [Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), Department of Physics, Jilin University, Changchun 130012 (China); Yan, Yu, E-mail: yanyu@jlu.edu.cn [Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), Department of Physics, Jilin University, Changchun 130012 (China)

2016-06-15

Using first-principles calculations, we study the geometrical structure, electronic structure and magnetic properties of substitutionally doped blue phosphorene with a series of nonmetallic atoms, including F, Cl, B, N, C, Si and O. The calculated formation energies and molecular dynamics simulations indicate that F, Cl, B, N, C, Si and O doped blue phosphorene are stable. Moreover, the substitutional doping of F, Cl, B and N cannot induce the magnetism in blue phosphorene due to the saturation or pairing of the valence electron of dopant and its neighboring P atoms. In contrast, ground states of C, Si and O doped blue phosphorene are spin-polarized and the magnetic moments induced by a doping atom are all 1.0 μ{sub B}, which is attributed to the appearance of an unpaired valence electron of C and Si and the formation of a nonbonding 3p electron of a neighboring P atom around O. Furthermore, the magnetic coupling between the moments induced by two C, Si and O are found to be long-range anti-ferromagnetic and the origin of the coupling can be attributed to the p–p hybridization interaction involving polarized electrons. - Highlights: • F, Cl, B, N, C, Si and O doped blue phosphorene are stable. • Substitutional doping of C, Si and O can produce the magnetism in blue phosphorene. • Magnetic coupling between two C, Si and O is long-range anti-ferromagnetic.
Defect-induced Catalysis toward the Oxygen Reduction Reaction in Single-walled Carbon Nanotube: Nitrogen doped and Non-nitrogen doped

International Nuclear Information System (INIS)

Lu, Di; Wu, Dan; Jin, Jian; Chen, Liwei

2016-01-01

Single-walled carbon nanotubes (SWNTs) are post-treated by argon (Ar) or ammonia (NH 3 ) plasma irradiation to introduce defects that are potentially related to catalysis towards the oxygen reduction reaction (ORR). Electrochemical characterization in alkali medium suggests that the plasma irradiated SWNTs demonstrate enhanced catalytic activity toward the ORR with a positively shifted threshold potential. Moreover the enhanced desired four-electron pathway catalytic activity, which exhibited as the positive shifted threshold potential, is independent of the nitrogen dopant. The nature of the defects is probed with Raman and X-ray photoelectron spectroscopy. The results indicate that the non-nitrogen doped defects of SWNTs contribute to the actual active site for the ORR.
Hierarchical porous nitrogen-doped partial graphitized carbon monoliths for supercapacitor

Energy Technology Data Exchange (ETDEWEB)

Yu, Yifeng; Du, Juan; Liu, Lei; Wang, Guoxu; Zhang, Hongliang; Chen, Aibing, E-mail: chen-ab@163.com [Hebei University of Science and Technology, College of Chemical and Pharmaceutical Engineering (China)

2017-03-15

Porous carbon monoliths have attracted great interest in many fields due to their easy availability, large specific surface area, desirable electronic conductivity, and tunable pore structure. In this work, hierarchical porous nitrogen-doped partial graphitized carbon monoliths (N–MC–Fe) with ordered mesoporous have been successfully synthesized by using resorcinol-formaldehyde as precursors, iron salts as catalyst, and mixed triblock copolymers as templates via a one-step hydrothermal method. In the reactant system, hexamethylenetetramine (HMT) is used as nitrogen source and one of the carbon precursors under hydrothermal conditions instead of using toxic formaldehyde. The N–MC–Fe show hierarchically porous structures, with interconnected macroporous and ordered hexagonally arranged mesoporous. Nitrogen element is in situ doped into carbon through decomposition of HMT. Iron catalyst is helpful to improve the graphitization degree and pore volume of N–MC–Fe. The synthesis strategy is user-friendly, cost-effective, and can be easily scaled up for production. As supercapacitors, the N–MC–Fe show good capacity with high specific capacitance and good electrochemical stability.
Interactions between nitrogen molecules and barium atoms on Ru (0001) surface

International Nuclear Information System (INIS)

Zhao Xinxin; Mi Yiming; Xu Hongxia; Wang Lili; Ren Li; Tao Xiangming; Tan Mingqiu

2011-01-01

We had performed first principles calculations on interactions between nitrogen molecules and barium atoms on Ru (0001) surface using density function theory methods. It was shown that effects of barium atoms weakened the bond strength of nitrogen molecules. The bond length of nitrogen molecule increases from 0.113 nm on Ru (001)-N 2 to 0.120 nm on Ru (001)-N 2 /Ba surface. While stretch vibrational frequency of nitrogen molecule decreased from 2222 cm -1 and charge transfer toward nitrogen molecule increased from 0.3 e to 1.1 e. Charge was mainly translated from 6 s orbitals of barium atoms to 4 d orbitals of substrate, which enhanced the hybridization between 4 d and 2 π orbitals and increased the dipole moment of 5 σ and d π orbitals of nitrogen molecule. The molecular dipole moment of nitrogen molecule was increased by -0.136 e Anstrom. It was suggested that barium had some characters to be an electronic promoter on the process of activating nitrogen molecules on Ru (0001) surface. (authors)

Reduction Expansion Synthesis as Strategy to Control Nitrogen Doping Level and Surface Area in Graphene

Directory of Open Access Journals (Sweden)

Russell Canty

2015-10-01

Full Text Available Graphene sheets doped with nitrogen were produced by the reduction-expansion (RES method utilizing graphite oxide (GO and urea as precursor materials. The simultaneous graphene generation and nitrogen insertion reactions are based on the fact that urea decomposes upon heating to release reducing gases. The volatile byproducts perform two primary functions: (i promoting the reduction of the GO and (ii providing the nitrogen to be inserted in situ as the graphene structure is created. Samples with diverse urea/GO mass ratios were treated at 800 °C in inert atmosphere to generate graphene with diverse microstructural characteristics and levels of nitrogen doping. Scanning electron microscopy (SEM and transmission electron microscopy (TEM were used to study the microstructural features of the products. The effects of doping on the samples structure and surface area were studied by X-ray diffraction (XRD, Raman Spectroscopy, and Brunauer Emmet Teller (BET. The GO and urea decomposition-reduction process as well as nitrogen-doped graphene stability were studied by thermogravimetric analysis (TGA coupled with mass spectroscopy (MS analysis of the evolved gases. Results show that the proposed method offers a high level of control over the amount of nitrogen inserted in the graphene and may be used alternatively to control its surface area. To demonstrate the practical relevance of these findings, as-produced samples were used as electrodes in supercapacitor and battery devices and compared with conventional, thermally exfoliated graphene.
Carbonization-dependent nitrogen-doped hollow porous carbon nanospheres synthesis and electrochemical study for supercapacitors

Science.gov (United States)

Zhou, Lingyun; Xie, Guohong; Chen, Xiling

2018-05-01

In this paper, a nitrogen-doped hollow microporous carbon nanospheres was synthesized via the combination of hyper-crosslinking mediated self-assembly and further pyrolysis using polylactide-b-polystyrene (PLA-b-PS) copolymers and aniline monomers as precursor. The pore structure and the correlative electrochemical performance of nitrogen-doped hollow microporous carbon nanospheres were affected by the molar mass ratio of aniline and PS in block copolymers and the carbonization conditions. The electrochemical measurements results showed that the obtained PLA150-PS250-N4-900-10H sample with nitrogen content of 3.57% and the BET surface area of 945 m2 g-1 displays the best capacitance performance. At a current density of 1.0 Ag-1, the resultant specific capacitance is 250 Fg-1. In addition, it also exhibits high capacitance retention of 98% after charging-discharging 1500 times at 25 Ag-1. The results demonstrate the nitrogen-doped hollow microporous carbon nanospheres can be used as promising supercapacitor electrode materials for high performance energy storage devices.
Structural Transformation upon Nitrogen Doping of Ultrananocrystalline Diamond Films by Microwave Plasma CVD

Directory of Open Access Journals (Sweden)

Chien-Chung Teng

2009-01-01

Full Text Available The molecular properties and surface morphology of undoped and N-doped ultra-nanocrystalline diamond (UNCD films deposited by microwave plasma CVD with addition of nitrogen are investigated with various spectroscopic techniques. The results of spatially resolved Raman scattering, ATR/FT-IR and XPS spectra show more amorphous and sp2/sp3 ratio characteristics in N-doped UNCD films. The surface morphology in AFM scans shows larger nanocrystalline diamond clusters in N-doped UNCD films. Incorporation of nitrogen into UNCD films has promoted an increase of amorphous sp2-bonded carbons in the grain boundaries and the size of nanocrystalline diamond grains that are well correlated to the reported enhancement of conductivity and structural changes of UNCD films.
Cysteine detection using a high-fluorescence sensor based on a nitrogen-doped graphene quantum dot–mercury(II) system

Energy Technology Data Exchange (ETDEWEB)

Liu, Zhenzhen; Gong, Yan; Fan, Zhefeng, E-mail: zhefengfan@126.com

2016-07-15

A novel and highly sensitive fluorescence sensor, which was based on the recovered fluorescence of a nitrogen-doped graphene quantum dot–Hg(II) system, was developed for cysteine detection. An easy, green, one-pot synthesis of nitrogen-doped graphene quantum dots was established by using citric acid and urea as carbon and nitrogen sources, respectively. The fluorescence of nitrogen-doped graphene quantum dots was significantly quenched by Hg(II) because of the efficient electron transfer between nitrogen-doped graphene quantum dots and Hg(II). Subsequently, fluorescence was recovered gradually upon cysteine addition to form a stable complex with Hg(II). The fluorescence sensor showed a response to cysteine within a wide concentration range of 0.05–30 μmol L{sup −1}, with a detection limit of 1.3 nmol L{sup −1}. The sensor was successfully applied to detect cysteine in honey and beer samples, with a recovery range of 98–105%.
Cysteine detection using a high-fluorescence sensor based on a nitrogen-doped graphene quantum dot–mercury(II) system

International Nuclear Information System (INIS)

Liu, Zhenzhen; Gong, Yan; Fan, Zhefeng

2016-01-01

A novel and highly sensitive fluorescence sensor, which was based on the recovered fluorescence of a nitrogen-doped graphene quantum dot–Hg(II) system, was developed for cysteine detection. An easy, green, one-pot synthesis of nitrogen-doped graphene quantum dots was established by using citric acid and urea as carbon and nitrogen sources, respectively. The fluorescence of nitrogen-doped graphene quantum dots was significantly quenched by Hg(II) because of the efficient electron transfer between nitrogen-doped graphene quantum dots and Hg(II). Subsequently, fluorescence was recovered gradually upon cysteine addition to form a stable complex with Hg(II). The fluorescence sensor showed a response to cysteine within a wide concentration range of 0.05–30 μmol L −1 , with a detection limit of 1.3 nmol L −1 . The sensor was successfully applied to detect cysteine in honey and beer samples, with a recovery range of 98–105%.
Reactivity of amino acid anions with nitrogen and oxygen atoms.

Science.gov (United States)

Wang, Zhe-Chen; Li, Ya-Ke; He, Sheng-Gui; Bierbaum, Veronica M

2018-02-14

For many decades, astronomers have searched for biological molecules, including amino acids, in the interstellar medium; this endeavor is important for investigating the hypothesis of the origin of life from space. The space environment is complex and atomic species, such as nitrogen and oxygen atoms, are widely distributed. In this work, the reactions of eight typical deprotonated amino acids (glycine, alanine, cysteine, proline, aspartic acid, histidine, tyrosine, and tryptophan) with ground state nitrogen and oxygen atoms are studied by experiment and theory. These amino acid anions do not react with nitrogen atoms. However, the reactions of these ions with oxygen atoms show an intriguing variety of ionic products and the reaction rate constants are of the order of 10 -10 cm 3 s -1 . Density functional calculations provide detailed mechanisms of the reactions, and demonstrate that spin conversion is essential for some processes. Our study provides important data and insights for understanding the kinetic and dynamic behavior of amino acids in space environments.
Electrical properties of MOS structures on nitrogen-doped Czochralski-grown silicon: A positron annihilation study

International Nuclear Information System (INIS)

Slugen, V.; Harmatha, L.; Tapajna, M.; Ballo, P.; Pisecny, P.; Sik, J.; Koegel, G.; Krsjak, V.

2006-01-01

Measurements of interface trap density, effective generation lifetime (GL) and effective surface generation velocity have been performed using different methods on selected MOS structures prepared on nitrogen-doped Czochralski-grown (NCz) silicon. The application of the positron annihilation technique using a pulsed low energy positron system (PLEPS) focused on the detection of nitrogen-related defects in NCz silicon in the near surface region. In the case of p-type Cz silicon, all the results could be used for the testing of homogeneity. In n-type Cz silicon, positron annihilation was found insensitive to nitrogen doping
In situ self-sacrificed template synthesis of vanadium nitride/nitrogen-doped graphene nanocomposites for electrochemical capacitors.

Science.gov (United States)

Liu, Hong-Hui; Zhang, Hong-Ling; Xu, Hong-Bin; Lou, Tai-Ping; Sui, Zhi-Tong; Zhang, Yi

2018-03-15

Vanadium nitride and graphene have been widely used as pseudo-capacitive and electric double-layer capacitor electrode materials for electrochemical capacitors, respectively. However, the poor cycling stability of vanadium nitride and the low capacitance of graphene impeded their practical applications. Herein, we demonstrated an in situ self-sacrificed template method for the synthesis of vanadium nitride/nitrogen-doped graphene (VN/NGr) nanocomposites by the pyrolysis of a mixture of dicyandiamide, glucose, and NH 4 VO 3 . Vanadium nitride nanoparticles of the size in the range of 2 to 7 nm were uniformly embedded into the nitrogen-doped graphene skeleton. Furthermore, the VN/NGr nanocomposites with a high specific surface area and pore volume showed a high specific capacitance of 255 F g -1 at 10 mV s -1 , and an excellent cycling stability (94% capacitance retention after 2000 cycles). The excellent capacitive properties were ascribed to the excellent conductivity of nitrogen-doped graphene, high surface area, high pore volume, and the synergistic effect between vanadium nitride and nitrogen-doped graphene.
A co-confined carbonization approach to aligned nitrogen-doped mesoporous carbon nanofibers and its application as an adsorbent

Energy Technology Data Exchange (ETDEWEB)

Chen, Aibing [College of Chemical and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang 050018 (China); Liu, Chao [College of Gemmology and Material Technics, Shijiazhuang University of Economic, Huaian Road 136, Shijiazhuang 050031 (China); Yu, Yifeng; Hu, Yongqi; Lv, Haijun; Zhang, Yue; Shen, Shufeng [College of Chemical and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang 050018 (China); Zhang, Jian [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

2014-07-15

Highlights: • MCNFs were synthesized by a co-confined carbonization method. • The diameter size of MCNFs with bimodal mesoporous structure can be modulated. • The obtained MCNFs manifest better adsorption capacity for SO{sub 2}, CO{sub 2} and Cd{sup 2+}. - Abstract: Nitrogen-doped carbon nanofibers (MCNFs) with an aligned mesoporous structure were synthesized by a co-confined carbonization method using anodic aluminum oxide (AAO) membrane and tetraethylorthosilicate (TEOS) as co-confined templates and ionic liquids as the precursor. The as-synthesized MCNFs with the diameter of 80–120 nm possessed a bulk nitrogen content of 5.3 wt% and bimodal mesoporous structure. The nitrogen atoms were mostly bound to the graphitic network in two forms, i.e. pyridinic and pyrrolic nitrogen, providing adsorption sites for acidic gases like SO{sub 2} and CO{sub 2}. Cyclic experiments revealed a considerable stability of MCNFs over 20 runs of SO{sub 2} adsorption and 15 runs for CO{sub 2} adsorption. The MCNFs also have a preferable adsorption performance for Cd{sup 2+}.
Defect-meditated efficient catalytic activity toward p-nitrophenol reduction: A case study of nitrogen doped calcium niobate system

International Nuclear Information System (INIS)

Su, Yiguo; Huang, Shushu; Wang, Tingting; Peng, Liman; Wang, Xiaojing

2015-01-01

Graphical abstract: A series of nitrogen doped Ca 2 Nb 2 O 7 was successfully prepared via ion-exchange method, which was found to be an efficient and green noble-metal-free catalyst toward catalytic reduction of p-nitrophenol. - Highlights: • Nitrogen doped Ca 2 Nb 2 O 7 was found to be an efficient and green noble-metal-free catalyst toward catalytic reduction of p-nitrophenol. • Defective nitrogen and oxygen species were found to play synergetic roles in the reduction of p-nitrophenol. • Nitrogen doped Ca 2 Nb 2 O 7 showed photo-synergistic promotion effects toward p-nitrophenol reduction under UV light irradiation. - Abstract: This work reported on the synthesis of a series of nitrogen doped Ca 2 Nb 2 O 7 with tunable nitrogen content that were found to be efficient and green noble-metal-free catalysts toward catalytic reduction of p-nitrophenol. XPS and ESR results indicated that the introduction of nitrogen in Ca 2 Nb 2 O 7 gave rise to a large number of defective nitrogen and oxygen species. Defective nitrogen and oxygen species were found to play synergetic roles in the reduction of p-nitrophenol. The underlying mechanism is completely different from those reported for metallic nanoparticles. Moreover, the more negative conduction band edge potential enabled nitrogen doped Ca 2 Nb 2 O 7 to show photo-synergistic effects that could accelerate the reduction rate toward p-nitrophenol under UV light irradiation. This work may provide a strategy for tuning the catalytic performance by modulating the chemical composition, electronic structure as well as surface defect chemistry
Well-dispersed NiO nanoparticles supported on nitrogen-doped carbon nanotube for methanol electrocatalytic oxidation in alkaline media

Energy Technology Data Exchange (ETDEWEB)

Wang, Pengcheng; Zhou, Yingke, E-mail: zhouyk888@hotmail.com; Hu, Min; Chen, Jian

2017-01-15

Highlights: • Nitrogen-doped carbon nanotube supporting ultrafine NiO nanoparticles with high dispersity are facile synthesized. • The nitrogen doping, calcination temperature and NiO loading present great effects on the catalyst morphology, structure and electrochemical performance. • NiO-NCNT-3x-400 demonstrates remarkable catalytic activity and stability for the methanol electrolytic oxidation reaction. - Abstract: Nitrogen-doped carbon nanotube supporting NiO nanoparticles were synthesized by a chemical precipitation process coupled with subsequent calcination. The morphology and structure of the composites were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and the electrochemical performance was evaluated using cyclic voltammetry and chronoamperometric technique. The effects of nitrogen doping, calcination temperature and content of NiO nanoparticles on the electrocatalytic activity toward methanol oxidation were systematically studied. The results show that the uniformly dispersed ultrafine NiO nanoparticles supported on nitrogen-doped carbon nanotube are obtained after calcination at 400 °C. The optimized composite catalysts present high electrocatalytic activity, fast charge-transfer process, excellent accessibility and stability for methanol oxidation reaction, which are promising for application in the alkaline direct methanol fuel cells.
Thermal and chemical durability of nitrogen-doped carbon nanotubes

International Nuclear Information System (INIS)

Liu Hao; Zhang Yong; Li Ruying; Sun Xueliang; Abou-Rachid, Hakima

2012-01-01

Nitrogen-doped carbon nanotubes (CN x tubes) with nitrogen content of 7.6 at.% are synthesized on carbon papers. Thermal and chemical stability of the nanotubes are investigated by thermogravimetric analysis, differential scanning calorimetry and X-ray photoelectron spectroscopy techniques. The results indicate that the nitrogen can be firmly kept in the nanotubes after annealing at 300 °C in air. Under an argon atmosphere, the nitrogen would not release until 670 °C, and half of the nitrogen incorporated is released after annealing at 700 °C for 30 min. Chemical stability investigation indicates that the nitrogen incorporated in the nanotubes is very stable under the thermal and acid environment comparable to working condition of proton exchange membrane (PEM) fuel cells. Profile of the nitrogen species inside the nanotubes reveals that graphite-like nitrogen releases slower than any other kind of nitrogen in the nanotubes during the chemical stability measurement. These CN x tubes synthesized by this simple chemical vapor deposition method are expected to be suitable for many applications, such as PEM fuel cells that work under both thermal and corrosive conditions and some other mild thermal environments.
Ion beam deposition of DLC and nitrogen doped DLC thin films for enhanced haemocompatibility on PTFE

International Nuclear Information System (INIS)

Srinivasan, S.; Tang, Y.; Li, Y.S.; Yang, Q.; Hirose, A.

2012-01-01

Diamond-like carbon (DLC) and N-doped DLC (DLC:N) thin films have been synthesized on polytetrafluroethylene (PTFE) and silicon wafers using ion beam deposition. Raman spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy and scanning electron microscopy were used to study the structural and morphological properties of the coated surface. The results show that the ion beam deposited DLC thin films exhibit high hardness and Young's modulus, low coefficient of friction and high adhesion to the substrate. Low concentration of nitrogen doping in DLC improves the mechanical properties and reduces the surface roughness. DLC coating decreases the surface energy and improves the wettability of PTFE. The platelet adhesion results show that the haemocompatibility of DLC coated PTFE, especially DLC:N coated PTFE, has been significantly enhanced as compared with uncoated PTFE. SEM observations show that the platelet reaction on the DLC and DLC:N coated PTFE was minimized as the platelets were much less aggregated and activated.
One-Step Synthesis of Microporous Carbon Monoliths Derived from Biomass with High Nitrogen Doping Content for Highly Selective CO2 Capture

OpenAIRE

Geng, Zhen; Xiao, Qiangfeng; Lv, Hong; Li, Bing; Wu, Haobin; Lu, Yunfeng; Zhang, Cunman

2016-01-01

The one-step synthesis method of nitrogen doped microporous carbon monoliths derived from biomass with high-efficiency is developed using a novel ammonia (NH3)-assisted activation process, where NH3 serves as both activating agent and nitrogen source. Both pore forming and nitrogen doping simultaneously proceed during the process, obviously superior to conventional chemical activation. The as-prepared nitrogen-doped active carbons exhibit rich micropores with high surface area and high nitrog...
A comparative investigation on the effects of nitrogen-doping into graphene on enhancing the electrochemical performance of SnO2/graphene for sodium-ion batteries.

Science.gov (United States)

Xie, Xiuqiang; Su, Dawei; Zhang, Jinqiang; Chen, Shuangqiang; Mondal, Anjon Kumar; Wang, Guoxiu

2015-02-21

SnO2/nitrogen-doped graphene nanohybrids have been synthesized by an in situ hydrothermal method, during which the formation of SnO2 nanocrystals and nitrogen doping of graphene occur simultaneously. The as-prepared SnO2/nitrogen-doped graphene nanohybrids exhibit enhanced electrochemical performance for sodium-ion batteries compared to SnO2/graphene nanocomposites. A systematic comparison between SnO2/nitrogen-doped graphene nanohybrids and the SnO2/graphene counterpart as anode materials for sodium-ion batteries has been conducted. The comparison is in a reasonable framework, where SnO2/nitrogen-doped graphene nanohybrids and the SnO2/graphene counterpart have the same SnO2 ratio, similar SnO2 crystallinity and particle size, close surface area and pore size. The results clearly manifest that the improved electron transfer efficiency of SnO2/nitrogen-doped graphene due to nitrogen-doping plays a more important role than the increased electro-active sites within graphene network in enhancing the electro-activity of SnO2/nitrogen-doped graphene nanohybrids compared to the SnO2/graphene counterpart. In contrast to the previous reports which often ascribe the enhanced electro-activity of nitrogen-doped graphene based composites to two nitrogen-doping effects (improving the electron transfer efficiency and increasing electro-active sites within graphene networks) in one single declaration, this work is expected to provide more specific information for understanding the effects of nitrogen-doping into graphene on improving the electrochemical performance of graphene based composites.
Nitrogen-doping effects on the growth, structure and electrical performance of carbon nanotubes obtained by spray pyrolysis method

Energy Technology Data Exchange (ETDEWEB)

Ionescu, Mihnea Ioan; Zhang Yong; Li Ruying [Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON N6A 5B9 (Canada); Abou-Rachid, Hakima [Defense Research and Development Canada - Valcartier, 2459 Boulevard PieXI Nord, Quebec, QC G3J 1X5 (Canada); Sun Xueliang, E-mail: xsun@eng.uwo.ca [Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON N6A 5B9 (Canada)

2012-03-01

Vertically aligned nitrogen-doped carbon nanotubes (CNTs) with modulated nitrogen content have been synthesized in a large scale by using spray pyrolysis chemical vapor deposition technique. The effects of nitrogen doping on the growth, structure and electrical performance of carbon nanotubes have been systematically examined. Field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman techniques have been employed to characterize the morphology, composition, and vibrational properties of nanotubes. The results indicate that the nitrogen incorporation significantly influences the growth rate, morphology, size and structure of nanotubes. Electrical measurement investigation of the nanotubes indicates that the change in electrical resistance increases with temperature and pressure as the nitrogen concentration increases inside the tubes. This work presents a versatile, safe, and easy way to scale up route of growing carbon nanotubes with controlled nitrogen content and modulated structure, and may provide an insight in developing various nitrogen-doped carbon-based nanodevices.
The nitrogen doping effect on the properties of Ge-In-Sb-Te phase-change recording media investigated by blue-light laser

International Nuclear Information System (INIS)

Yeh, T.-T.; Hsieh, T.-E.; Shieh, H.-P.D.

2005-01-01

This work investigates the thermal, optical and recrystallization properties as well as the microstructure of nitrogen-doped Ge-In-Sb-Te (GIST) phase-change material when irradiated by blue-light laser. The experimental results showed that nitrogen doping at the condition of N 2 /Ar sputtering gas flow ratio equals to 3% might enhance the recrystallization speed of GIST recording layer up to 1.5 times. However, the disk failed when too much nitrogen (N 2 /Ar ≥ 5.0%) was introduced. The data obtained by differential scanning calorimetry, X-ray diffraction and ellipsometry revealed changes of thermal and optical properties due to the nitrogen doping in GIST. When appropriate amount of nitrogen was added, the activation energy (E a ) of amorphous-crystalline phase transition of GIST decreased and the optical constants of amorphous and crystalline phases (except the k value of amorphous phase) gradually reduced with the increase of wavelength in the range of 600-750 nm. Modulation simulation based on the reflectively of doped GIST layers obtained from static test indicated that appropriate nitrogen doping benefited the signal characteristics of optical disks. Transmission electron microscopy observed numerous tiny precipitates uniformly distributed in the doped GIST layers. These were believed to be nitride particles generated by nitrogen doping that might offer the preferential sites for amorphous-crystalline phase transition so that the recrystallization speed was accelerated
Biexciton emission from single isoelectronic traps formed by nitrogen-nitrogen pairs in GaAs

Energy Technology Data Exchange (ETDEWEB)

Takamiya, Kengo; Fukushima, Toshiyuki; Yagi, Shuhei; Hijikata, Yasuto; Yaguchi, Hiroyuki [Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku , Saitama 338-8570 (Japan); Mochizuki, Toshimitsu; Yoshita, Masahiro; Akiyama, Hidefumi [Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Kuboya, Shigeyuki; Onabe, Kentaro [Department of Advanced Materials Science, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Katayama, Ryuji [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

2013-12-04

We have studied photoluminescence (PL) from individual isoelectronic traps formed by nitrogen-nitrogen (NN) pairs in GaAs. Sharp emission lines due to exciton and biexciton were observed from individual isoelectronic traps in nitrogen atomic-layer doped (ALD) GaAs. The binding energy of biexciton bound to individual isoelectronic traps was approximately 8 meV. Both the exciton and biexciton luminescence lines show completely random polarization and no fine-structure splitting. These results are desirable to the application to the quantum cryptography used in the field of quantum information technology.
Green synthesis of sulfur- and nitrogen-co-doped carbon dots using ionic liquid as a precursor and their application in Hg2+ detection

International Nuclear Information System (INIS)

Zhuo, Kelei; Sun, Dong; Xu, Panpan; Wang, Chunfeng; Cao, Yingying; Chen, Yujuan; Liu, Jianming

2017-01-01

A facile and environment-friendly method was developed to synthesize sulfur- and nitrogen-co-doped carbon dots (S/N-CDs) via one step hydrothermal treatment of 1-butyl-3-methylimidazolium 2-amino-3-mercaptopropionic acid salt ionic liquid and polyethylene glycol. It was found that the prepared S/N-CDs were nearly spherical nanoparticles. And then the size of the as-prepared S/N-CDs became smaller with the extension of reaction time, the amorphous carbon was gradually transformed into a crystal structure of carbon dots and a higher reaction temperature favors the formation of carbon dots with higher quantum yields. It was also found that sulfur atoms in the S/N-CDs change the surface structures of CDs to some extent. Higher quantum yield of the S/N-CDs should attribute to the synergistic effect of co-doped nitrogen and sulfur atoms. The S/N-CDs display stable and strong florescence, high water solubility, excitation-dependent emission behavior, particularly the up-conversion photoluminescence performance. Furthermore, the as-prepared S/N-CDs were used as a sensitive probe for Hg 2+ detection in aqueous solutions, with high selectivity and sensitivity. Particularly, the detection limit could reach as low as 0.6 nM (S/N=3).
A first-principles study on the magnetic properties of nonmetal atom doped phosphorene monolayers.

Science.gov (United States)

Zheng, Huiling; Zhang, Jianmin; Yang, Baishun; Du, Xiaobo; Yan, Yu

2015-07-07

In order to induce magnetism in two-dimensional semiconductors for their applications in spintronic devices and novel chemical and electronic properties of semiconducting phosphorene, the geometrical structure, electronic and magnetic properties of doped phosphorene monolayers with a series of nonmetal atoms, including H, F, Cl, Br, I, B, C, Si, N, As, O, S and Se, were systematically investigated using first-principles calculations. The results show that although the substitutional doping of H, F, Cl, Br, I, B, N, O, S or Se results in large structural deformation at the doping sites of phosphorene monolayers, all neutral nonmetal atom doped systems are stable. The calculated formation energies reveal that the substitutional doping of numerous nonmetal atoms in phosphorene monolayer are possible under appropriate experimental conditions, and the charged dopants C(-), Si(-), S(+) and Se(+) are stable. Moreover, the substitutional doping of H, F, Cl, Br, I, B, N, As, C(-), Si(-), S(+) or Se(+) cannot induce magnetism in phosphorene monolayer due to the saturation or pairing of valence electrons of dopant and its neighboring P atoms, whereas ground states of neutral C, Si, O, S or Se doped systems are magnetic due to the appearance of an unpaired valence electron of C and Si or the formation of a nonbonding 3p electron of a neighboring P atom around O, S and Se. Furthermore, the magnetic coupling between the moments induced by two Si, O, S or Se are long-range anti-ferromagnetic and the coupling can be attributed to the hybridization interaction involving polarized electrons, whereas the coupling between the moments induced by two C is weak.

Polymer-mediated synthesis of a nitrogen-doped carbon aerogel with highly dispersed Pt nanoparticles for enhanced electrocatalytic activity

International Nuclear Information System (INIS)

2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" data-affiliation=" (World Class University (WCU) Program of Chemical Convergence for Energy & Environment C2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" >Kim, Gil-Pyo; 2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" data-affiliation=" (World Class University (WCU) Program of Chemical Convergence for Energy & Environment C2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" >Lee, Minzae; Lee, Yoon Jae; 2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" data-affiliation=" (World Class University (WCU) Program of Chemical Convergence for Energy & Environment C2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" >Bae, Seongjun; 2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" data-affiliation=" (World Class University (WCU) Program of Chemical Convergence for Energy & Environment C2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" >Song, Hyeon Dong; Song, In Kyu; 2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" data-affiliation=" (World Class University (WCU) Program of Chemical Convergence for Energy & Environment C2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" >Yi, Jongheop

2016-01-01

Highlights: • Highly dispersed Pt nanoparticles on N-doped carbon aerogel were synthesized for ORR. • Poly(ethyleneimine) was used as nitrogen source and as nucleation sites for Pt. • Precise discussion were conducted to clarify the effect of poly(ethyleneimine). • High Pt dispersion and N-doping results in superior electrocatalytic activity. - Abstract: A simple chemical process for the direct synthesis of a nitrogen (N)-doped carbon aerogel (NCA) with highly dispersed Pt nanoparticles via a poly(ethyleneimine) (PEI)-assisted strategy is described. A resorcinol-formaldehyde (RF) gel was treated with water soluble cationic PEI, which mainly functions as an anchoring site for metal ions. The functionalized PEI chains on the surface of the RF gel resulted in the unique formation of chemical complexes, with PtCl 6 2− anchored to the RF gel, and subsequent homogeneous metal nanoparticle growth. The abundant amino groups containing PEI grafted to the RF gel also allowed the nitrogen atoms to be incorporated into the carbon framework, which can directly be converted into a NCA. The spherical Pt nanoparticles in the resulting material (Pt/NCA) were highly dispersed on the surface of the NCA without any evidenced of agglomeration, even after a thermal annealing at 900 °C. Compared with a Pt/CA synthesized by a conventional reduction method, the Pt/NCA showed enhanced electrochemical performance with a high electrochemically active surface area (191.1 cm 2 g −1 ) and electrocatalytic activity (V onset = 0.95 V vs. RHE) with respect to oxygen reduction. The superior electrocatalytic activities of the Pt/NCA can be attributed to the synergistic effect of the highly dispersed Pt nanoparticles and the N-doped carbon supports that were prepared using the PEI-assisted strategy. The findings reported herein suggest that the use of PEI can be effectively extended to broad applications that require the homogeneous deposition of metal nanoparticles.
Synthesis and Doping of Ligand-Protected Atomically-Precise Metal Nanoclusters

KAUST Repository

Aljuhani, Maha A.

2016-05-01

Rapidly expanding research in nanotechnology has led to exciting progress in a versatile array of applications from medical diagnostics to catalysis. This success resulted from the manipulation of the desired properties of nanomaterials by controlling their size, shape, and composition. Among the most thriving areas of research about nanoparticle is the synthesis and doping of the ligand-protected atomically-precise metal nanoclusters. In this thesis, we developed three different novel metal nanoclusters, such as doped Ag29 with five gold (Au) atoms leading to enhance its quantum yield with remarkable stability. We also developed half-doped (alloyed) cluster of Ni6 nanocluster with molybdenum (Mo). This enabled enhanced stability and better catalytic activity. The third metal nanocluster that we synthesized was Au28 nanocluster by using di-thiolate as the ligand stabilizer instead of mono-thiolate. The new metal clusters obtained have been characterized by spectroscopic, electrochemical and crystallographic methods.
The origin of the enhanced performance of nitrogen-doped MoS_2 in lithium ion batteries

International Nuclear Information System (INIS)

Liu, Qiuhong; Weijun, Xia; Wu, Zhenjun; Huo, Jia; Liu, Dongdong; Wang, Shuangyin; Wang, Qiang

2016-01-01

MoS_2 with a similar layered structure to graphene has been widely applied in various areas including lithium ion batteries. However, low conductivity, capacity fading and poor rate performance are still the main challenges for MoS_2 anode materials. In this work, for the first time, we prepared nitrogen-doped MoS_2 (N-MoS_2) nanosheets through a simple two-step method involving the preparation of MoS_2 with defects by the hydrothermal method, followed by sintering in a NH_3 atmosphere. Our electrochemical characterizations and density functional theory calculations demonstrated that nitrogen doping could enhance the electron conductivity and showed higher specific capacity than pristine MoS_2 as anode materials of lithium ion batteries, which can be attributed to the faster transportation of electrons and ions because of nitrogen doping. This work helps us understand the origin of the enhanced performance of N-doped MoS_2 in lithium ion batteries. (paper)
Highly n -doped graphene generated through intercalated terbium atoms

Science.gov (United States)

Daukiya, L.; Nair, M. N.; Hajjar-Garreau, S.; Vonau, F.; Aubel, D.; Bubendorff, J. L.; Cranney, M.; Denys, E.; Florentin, A.; Reiter, G.; Simon, L.

2018-01-01

We obtained highly n -type doped graphene by intercalating terbium atoms between graphene and SiC(0001) through appropriate annealing in ultrahigh vacuum. After terbium intercalation angle-resolved-photoelectron spectroscopy (ARPES) showed a drastic change in the band structure around the K points of the Brillouin zone: the well-known conical dispersion band of a graphene monolayer was superposed by a second conical dispersion band of a graphene monolayer with an electron density reaching 1015cm-2 . In addition, we demonstrate that atom intercalation proceeds either below the buffer layer or between the buffer layer and the monolayer graphene. The intercalation of terbium below a pure buffer layer led to the formation of a highly n -doped graphene monolayer decoupled from the SiC substrate, as evidenced by ARPES and x-ray photoelectron spectroscopy measurements. The band structure of this highly n -doped monolayer graphene showed a kink (a deviation from the linear dispersion of the Dirac cone), which has been associated with an electron-phonon coupling constant one order of magnitude larger than those usually obtained for graphene with intercalated alkali metals.
Half-metallic ferromagnetism in nitrogen - doped ionic insulator (Li2O): a DFT study

International Nuclear Information System (INIS)

Eithiraj, R.D.; Kalpana, G.

2010-01-01

The tight binding linear muffin-tin orbital (TB-LMTO) method, is used to study the electronic structure and magnetism in nitrogen - doped Li 2 O (antifluorite - CaF 2 structure). Total energy calculations show that the antifluorite ferromagnetic state is more stable than the antifluorite non-magnetic state at equilibrium volume. Ground state properties such as equilibrium lattice constant and bulk modulus were calculated. The calculations reveal that non-magnetic impurities can induce stable half-metallic ferromagnetic ground state in Li 2 O. The magnetic moment of nitrogen doped Li 2 O can be tuned over a range between 1.00 μ B and 3.00 μ B by changing the concentration of nitrogen from 25% to 75%. (author)
A comparison of nitrogen-doped sonoelectrochemical and chemical graphene nanosheets as hydrogen peroxide sensors.

Science.gov (United States)

Wu, Yi-Shan; Liu, Zhe-Ting; Wang, Tzu-Pei; Hsu, Su-Yang; Lee, Chien-Liang

2018-04-01

Nitrogen-doped graphene nanosheet (N-SEGN) with pyrrolic nitrogen and 5-9 vacancy defects has been successfully prepared from a hydrothermal reaction of tetra-2-pyridinylpyrazine and sonoelectrochemistry-exfoliated graphene nanosheet, with point defects. Additionally, based on the same reaction using chemically reduced graphene oxide, nitrogen-doped chemically reduced graphene oxide (N-rGO) with graphitic nitrogen was prepared. The N-SEGN and N-rGO were used as a non-enzymatic H 2 O 2 sensors. The sensitivity of the N-SEGN was 231.3 μA·mM -1 ·cm -2 , much greater than 57.3 μA·mM -1 ·cm -2 of N-rGO. The N-SEGN showed their potential for being a H 2 O 2 sensor. Copyright © 2017 Elsevier B.V. All rights reserved.
Interplay of Nitrogen-Atom Inversion and Conformational Inversion in Enantiomerization of 1H-1-Benzazepines.

Science.gov (United States)

Ramig, Keith; Subramaniam, Gopal; Karimi, Sasan; Szalda, David J; Ko, Allen; Lam, Aaron; Li, Jeffrey; Coaderaj, Ani; Cavdar, Leyla; Bogdan, Lukasz; Kwon, Kitae; Greer, Edyta M

2016-04-15

A series of 2,4-disubstituted 1H-1-benzazepines, 2a-d, 4, and 6, were studied, varying both the substituents at C2 and C4 and at the nitrogen atom. The conformational inversion (ring-flip) and nitrogen-atom inversion (N-inversion) energetics were studied by variable-temperature NMR spectroscopy and computations. The steric bulk of the nitrogen-atom substituent was found to affect both the conformation of the azepine ring and the geometry around the nitrogen atom. Also affected were the Gibbs free energy barriers for the ring-flip and the N-inversion. When the nitrogen-atom substituent was alkyl, as in 2a-c, the geometry of the nitrogen atom was nearly planar and the azepine ring was highly puckered; the result was a relatively high-energy barrier to ring-flip and a low barrier to N-inversion. Conversely, when the nitrogen-atom substituent was a hydrogen atom, as in 2d, 4, and 6, the nitrogen atom was significantly pyramidalized and the azepine ring was less puckered; the result here was a relatively high energy barrier to N-inversion and a low barrier to ring-flip. In these N-unsubstituted compounds, it was found computationally that the lowest-energy stereodynamic process was ring-flip coupled with N-inversion, as N-inversion alone had a much higher energy barrier.
High electrocatalytic performance of nitrogen-doped carbon nanofiber-supported nickel oxide nanocomposite for methanol oxidation in alkaline medium

Energy Technology Data Exchange (ETDEWEB)

Al-Enizi, Abdullah M. [Department of Chemistry, King Saud University, PO Box: 2455, Riyadh 11451 (Saudi Arabia); Elzatahry, Ahmed A., E-mail: aelzatahry@ksu.edu.sa [Materials Science and Technology Program, College of Arts and Science, Qatar University, Doha 2713 (Qatar); Advanced Technology and New Materials Research Institute, City of Scientific Research and Technology Applications, New Borg El-Arab City, Alexandria 21934 (Egypt); Abdullah, Aboubakr M., E-mail: bakr@qu.edu.qa [Center for Advanced Materials, Qatar University, Doha 2713 (Qatar); Vinu, Ajayan [Future Industries Institute, University of South Australia, Building X-X2-09, Mawson Lakes Campus, Mawson Lakes 5095 SA (Australia); Iwai, Hideo [Materials Analysis Station, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047 (Japan); Al-Deyab, Salem S. [Petrochemical Research Chair, Department of Chemistry, King Saud University, PO Box: 2455, Riyadh 11451 (Saudi Arabia)

2017-04-15

Highlights: • A mixture of Polyvinylpyrrolidone (PVP), graphene and emeraldine base polyaniline (PANi) was electrospun and used as starting materials to prepare a nitrogen-doped carbon nanofiber (N-CNF). • Nickel oxide was loaded on the N-CNF to form a nanocomposite which was calcined later at different temperatures. • The effect of calcination temperature on the electrocatalytic behavior of the nanocomposite was studied which shows that the nanocomposite calcined at 500 °C was proved to be very high compared to the other calcination temperatures. • The stability of catalyst was excellent and its resistance to the adsorption of the intermediates generated from the methanol oxidation was very high. - Abstract: Nitrogen-Doped Carbon Nanofiber (N-CNF)–supported NiO composite was prepared by electrospinning a sol-gel mixture of graphene and polyaniline (PANi) with aqueous solutions of Polyvinylpyrrolidone (PVP) followed by a high-temperature annealing process. The electrospun was stabilized for 2 h at 280 °C, carbonized for 5 h at 1200 °C then loaded by 10% NiO. The electrocatalytic activities of the produced nanocomposite have been studied using cyclic voltammetry, and chronoamperometry. Also, N-CNF was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface area (BET), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), and scanning-electron microscopy (SEM). The obtained N-doped carbon nanofiber was found to have a nitrogen content of 2.6 atomic% with a diameter range of (140–160) nm, and a surface area (393.3 m{sup 2} g{sup −1}). In addition, it showed a high electrocatalytic behavior towards methanol oxidation reaction in alkaline medium and high stability and resistivity to the adsorption of intermediates.
Methanol electrocatalytic oxidation on Pt nanoparticles on nitrogen doped graphene prepared by the hydrothermal reaction of graphene oxide with urea

International Nuclear Information System (INIS)

Xu, Xiao; Zhou, Yingke; Yuan, Tao; Li, Yawei

2013-01-01

A facile hydrothermal reaction of graphene oxide with urea was used to produce nitrogen doped graphene, and Pt nanoparticles were deposited on the obtained nitrogen doped graphene by the NaBH 4 reduction route. The morphology and microstructure of the synthesized catalysts were characterized by transmission electron microscopy, X-ray powder diffraction and X-ray photoelectron spectroscopy, while the functional groups on the surface of the catalysts were investigated by the Fourier transform infrared spectroscopy and ultraviolet-visible absorption spectra. Cyclic voltammetry, chronoamperometry and electrochemical impedance techniques were carried out to evaluate the methanol electrocatalytic oxidation activity and durability of Pt catalysts supported on the nitrogen doped graphene. The results showed that nitrogen doping and reduction of GO were achieved simultaneously by the facile hydrothermal reaction, which had beneficial effects for the deposition process and electrocatalytic activity of Pt nanoparticles. The Pt catalysts supported on the nitrogen doped graphene substrate presented excellent activity and durability of methanol oxidation reaction, which might be promising for application in direct methanol fuel cells
Biocompatibility and antibacterial activity of nitrogen-doped titanium dioxide nanoparticles for use in dental resin formulations.

Science.gov (United States)

Zane, Andrew; Zuo, Ranfang; Villamena, Frederick A; Rockenbauer, Antal; Digeorge Foushee, Ann Marie; Flores, Kristin; Dutta, Prabir K; Nagy, Amber

The addition of antibacterial functionality to dental resins presents an opportunity to extend their useful lifetime by reducing secondary caries caused by bacterial recolonization. In this study, the potential efficacy of nitrogen-doped titanium dioxide nanoparticles for this purpose was determined. Nitrogen doping was carried out to extend the ultraviolet absorbance into longer wavelength blue light for increased biocompatibility. Titanium dioxide nanoparticles (approximately 20-30 nm) were synthesized with and without nitrogen doping using a sol-gel method. Ultraviolet-Visible spectroscopy indicated a band of trap states, with increasing blue light absorbance as the concentration of the nitrogen dopant increased. Electron paramagnetic resonance measurements indicated the formation of superoxide and hydroxyl radicals upon particle exposure to visible light and oxygen. The particles were significantly toxic to Escherichia coli in a dose-dependent manner after a 1-hour exposure to a blue light source (480 nm). Intracellular reactive oxygen species assay demonstrated that the particles caused a stress response in human gingival epithelial cells when exposed to 1 hour of blue light, though this did not result in detectable release of cytokines. No decrease in cell viability was observed by water-soluble tetrazolium dye assay. The results show that nitrogen-doped titanium dioxide nanoparticles have antibacterial activity when exposed to blue light, and are biocompatible at these concentrations.
Mesoporous nitrogen-doped carbon microfibers derived from Mg-biquinoline-dicarboxy compound for efficient oxygen electroreduction

Energy Technology Data Exchange (ETDEWEB)

Kong, Aiguo, E-mail: agkong@chem.ecnu.edu.cn [School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241 (China); Fan, Xiaohong; Chen, Aoling [School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241 (China); Zhang, Hengiang [School of Chemistry and Chemical Engineering, Hebei Normal University for Nationalities, Chengde 067000 (China); Shan, Yongkui, E-mail: agkong@chem.ecnu.edu.cn [School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241 (China)

2017-02-15

An in-situ MgO-templating synthesis route was introduced to obtain the mesoporous nitrogen-doped carbon microfibers by thermal conversion of new Mg-2,2′-biquinoline 4,4-dicarboxy acid coordination compound (Mg-DCA) microfibers. The investigated crystal structure of Mg-DCA testified that the assembling of Mg{sup 2+} and DCA through Mg-O coordination bond and hydrogen bond contributed to the formation of one-dimensional (1D) crystalline Mg-DCA microfibers. The nitrogen-doped carbons derived from the pyrolysis of Mg-DCA showed the well-defined microfiber morphology with high mesopore-surface area. Such mesoporous microfibers exhibited the efficient catalytic activity for oxygen reduction reaction (ORR) in alkaline solutions with better stability and methanol-tolerance performance. - Graphical abstract: Mesoporous nitrogen-doped carbon microfibers with efficient oxygen electroreduction activity were prepared by thermal conversion of new Mg-biquinoline-based coordination compound microfibers.
Investigation of Physical Properties and Electrochemical Behavior of Nitrogen-Doped Diamond-Like Carbon Thin Films

Directory of Open Access Journals (Sweden)

Rattanakorn Saensak

2014-03-01

Full Text Available This work reports characterizations of diamond-like carbon (DLC films used as electrodes for electrochemical applications. DLC thin films are prepared on glass slides and silicon substrates by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD using a gas mixture of methane and hydrogen. In addition, the DLC films are doped with nitrogen in order to reduce electrical resistivity. Compared to the undoped DLC films, the electrical resistivity of nitrogen-doped (N-doped DLC films is decreased by three orders of magnitude. Raman spectroscopy and UV/Vis spectroscopy analyses show the structural transformation in N-doped DLC films that causes the reduction of band gap energy. Contact angle measurement at N-doped DLC films indicates increased hydrophobicity. The results obtained from the cyclic voltammetry measurements with Fe(CN63-/Fe(CN64- redox species exhibit the correlation between the physical properties and electrochemical behavior of DLC films.
First-principles study of nitrogen doping in cubic and amorphous Ge2Sb2Te5

Science.gov (United States)

Caravati, S.; Colleoni, D.; Mazzarello, R.; Kühne, T. D.; Krack, M.; Bernasconi, M.; Parrinello, M.

2011-07-01

We investigated the structural, electronic and vibrational properties of amorphous and cubic Ge2Sb2Te5 doped with N at 4.2 at.% by means of large scale ab initio simulations. Nitrogen can be incorporated in molecular form in both the crystalline and amorphous phases at a moderate energy cost. In contrast, insertion of N in the atomic form is very energetically costly in the crystalline phase, though it is still possible in the amorphous phase. These results support the suggestion that N segregates at the grain boundaries during the crystallization of the amorphous phase, resulting in a reduction in size of the crystalline grains and an increased crystallization temperature.
Synthesis of ultrathin nitrogen-doped graphitic carbon nanocages as advanced electrode materials for supercapacitor.

Science.gov (United States)

Tan, Yueming; Xu, Chaofa; Chen, Guangxu; Liu, Zhaohui; Ma, Ming; Xie, Qingji; Zheng, Nanfeng; Yao, Shouzhuo

2013-03-01

Synthesis of nitrogen-doped carbons with large surface area, high conductivity, and suitable pore size distribution is highly desirable for high-performance supercapacitor applications. Here, we report a novel protocol for template synthesis of ultrathin nitrogen-doped graphitic carbon nanocages (CNCs) derived from polyaniline (PANI) and their excellent capacitive properties. The synthesis of CNCs involves one-pot hydrothermal synthesis of Mn3O4@PANI core-shell nanoparticles, carbonization to produce carbon coated MnO nanoparticles, and then removal of the MnO cores by acidic treatment. The CNCs prepared at an optimum carbonization temperature of 800 °C (CNCs-800) have regular frameworks, moderate graphitization, high specific surface area, good mesoporosity, and appropriate N doping. The CNCs-800 show high specific capacitance (248 F g(-1) at 1.0 A g(-1)), excellent rate capability (88% and 76% capacitance retention at 10 and 100 A g(-1), respectively), and outstanding cycling stability (~95% capacitance retention after 5000 cycles) in 6 M KOH aqueous solution. The CNCs-800 can also exhibit great pseudocapacitance in 0.5 M H2SO4 aqueous solution besides the large electrochemical double-layer capacitance. The excellent capacitance performance coupled with the facile synthesis of ultrathin nitrogen-doped graphitic CNCs indicates their great application potential in supercapacitors.
Rational Design of Single Molybdenum Atoms Anchored on N-Doped Carbon for Effective Hydrogen Evolution Reaction.

Science.gov (United States)

Chen, Wenxing; Pei, Jiajing; He, Chun-Ting; Wan, Jiawei; Ren, Hanlin; Zhu, Youqi; Wang, Yu; Dong, Juncai; Tian, Shubo; Cheong, Weng-Chon; Lu, Siqi; Zheng, Lirong; Zheng, Xusheng; Yan, Wensheng; Zhuang, Zhongbin; Chen, Chen; Peng, Qing; Wang, Dingsheng; Li, Yadong

2017-12-11

The highly efficient electrochemical hydrogen evolution reaction (HER) provides a promising pathway to resolve energy and environment problems. An electrocatalyst was designed with single Mo atoms (Mo-SAs) supported on N-doped carbon having outstanding HER performance. The structure of the catalyst was probed by aberration-corrected scanning transmission electron microscopy (AC-STEM) and X-ray absorption fine structure (XAFS) spectroscopy, indicating the formation of Mo-SAs anchored with one nitrogen atom and two carbon atoms (Mo 1 N 1 C 2 ). Importantly, the Mo 1 N 1 C 2 catalyst displayed much more excellent activity compared with Mo 2 C and MoN, and better stability than commercial Pt/C. Density functional theory (DFT) calculation revealed that the unique structure of Mo 1 N 1 C 2 moiety played a crucial effect to improve the HER performance. This work opens up new opportunities for the preparation and application of highly active and stable Mo-based HER catalysts. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Atomic layer deposition of Al-doped ZnO thin films

Energy Technology Data Exchange (ETDEWEB)

Tynell, Tommi; Yamauchi, Hisao; Karppinen, Maarit; Okazaki, Ryuji; Terasaki, Ichiro [Department of Chemistry, Aalto University, FI-00076 Aalto (Finland); Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)

2013-01-15

Atomic layer deposition has been used to fabricate thin films of aluminum-doped ZnO by depositing interspersed layers of ZnO and Al{sub 2}O{sub 3} on borosilicate glass substrates. The growth characteristics of the films have been investigated through x-ray diffraction, x-ray reflection, and x-ray fluorescence measurements, and the efficacy of the Al doping has been evaluated through optical reflectivity and Seebeck coefficient measurements. The Al doping is found to affect the carrier density of ZnO up to a nominal Al dopant content of 5 at. %. At nominal Al doping levels of 10 at. % and higher, the structure of the films is found to be strongly affected by the Al{sub 2}O{sub 3} phase and no further carrier doping of ZnO is observed.
Nitrogen-Doped Carbon Nanotube/Graphite Felts as Advanced Electrode Materials for Vanadium Redox Flow Batteries.

Science.gov (United States)

Wang, Shuangyin; Zhao, Xinsheng; Cochell, Thomas; Manthiram, Arumugam

2012-08-16

Nitrogen-doped carbon nanotubes have been grown, for the first time, on graphite felt (N-CNT/GF) by a chemical vapor deposition approach and examined as an advanced electrode for vanadium redox flow batteries (VRFBs). The unique porous structure and nitrogen doping of N-CNT/GF with increased surface area enhances the battery performance significantly. The enriched porous structure of N-CNTs on graphite felt could potentially facilitate the diffusion of electrolyte, while the N-doping could significantly contribute to the enhanced electrode performance. Specifically, the N-doping (i) modifies the electronic properties of CNT and thereby alters the chemisorption characteristics of the vanadium ions, (ii) generates defect sites that are electrochemically more active, (iii) increases the oxygen species on CNT surface, which is a key factor influencing the VRFB performance, and (iv) makes the N-CNT electrochemically more accessible than the CNT.
A one-step carbonization route towards nitrogen-doped porous carbon hollow spheres with ultrahigh nitrogen content for CO 2 adsorption

KAUST Repository

Wang, Yu

2015-01-01

© The Royal Society of Chemistry 2015. Nitrogen doped porous carbon hollow spheres (N-PCHSs) with an ultrahigh nitrogen content of 15.9 wt% and a high surface area of 775 m² g^-1 were prepared using Melamine-formaldehyde nanospheres as hard templates and nitrogen sources. The N-PCHSs were completely characterized and were found to exhibit considerable CO2 adsorption performance (4.42 mmol g^-1).
Fast Conversion of Ionic Liquids and Poly(Ionic Liquid)s into Porous Nitrogen-Doped Carbons in Air.

Science.gov (United States)

Men, Yongjun; Ambrogi, Martina; Han, Baohang; Yuan, Jiayin

2016-04-08

Ionic liquids and poly(ionic liquid)s have been successfully converted into nitrogen-doped porous carbons with tunable surface area up to 1200 m²/g at high temperatures in air. Compared to conventional carbonization process conducted under inert gas to produce nitrogen-doped carbons, the new production method was completed in a rather shorter time without noble gas protection.
Mechanical properties and electronic structure of edge-doped graphene nanoribbons with F, O, and Cl atoms.

Science.gov (United States)

Piriz, Sebastián; Fernández-Werner, Luciana; Pardo, Helena; Jasen, Paula; Faccio, Ricardo; Mombrú, Álvaro W

2017-08-16

In this study, we present the structural, electronic, and mechanical properties of edge-doped zigzag graphene nanoribbons (ZGNRs) doped with fluorine, oxygen, and chlorine atoms. To the best of our knowledge, to date, no experimental results concerning the mechanical properties of graphene-derived nanoribbons have been reported in the literature. Simulations indicate that Cl- and F-doped ZGNRs present an equivalent 2-dimensional Young's modulus E 2D , which seems to be higher than those of graphene and H-doped ZGNRs. This is a consequence of the electronic structure of the system, particularly originating from strong interactions between the dopant atoms localized at the edges. The interaction between dopant atoms located at the edges is higher for Cl and lower for F and O atoms. This is the origin of the observed trend, in which E > E > E for all the analyzed ZGNRs.

Bottom-up synthesis of nitrogen-doped graphene sheets for ultrafast lithium storage

Science.gov (United States)

Tian, Lei-Lei; Wei, Xian-Yong; Zhuang, Quan-Chao; Jiang, Chen-Hui; Wu, Chao; Ma, Guang-Yao; Zhao, Xing; Zong, Zhi-Min; Sun, Shi-Gang

2014-05-01

A facile bottom-up strategy was developed to fabricate nitrogen-doped graphene sheets (NGSs) from glucose using a sacrificial template synthesis method. Three main types of nitrogen dopants (pyridinic, pyrrolic and graphitic nitrogens) were introduced into the graphene lattice, and an inimitable microporous structure of NGS with a high specific surface area of 504 m2 g-1 was obtained. Particularly, with hybrid features of lithium ion batteries and Faradic capacitors at a low rate and features of Faradic capacitors at a high rate, the NGS presents a superior lithium storage performance. During electrochemical cycling, the NGS electrode afforded an enhanced reversible capacity of 832.4 mA h g-1 at 100 mA g-1 and an excellent cycling stability of 750.7 mA h g-1 after 108 discharge-charge cycles. Furthermore, an astonishing rate capability of 333 mA h g-1 at 10 000 mA g-1 and a high rate cycle performance of 280.6 mA h g-1 even after 1200 cycles were also achieved, highlighting the significance of nitrogen doping on the maximum utilization of graphene-based materials for advanced lithium storage.
Bottom-up synthesis of nitrogen-doped graphene sheets for ultrafast lithium storage.

Science.gov (United States)

Tian, Lei-Lei; Wei, Xian-Yong; Zhuang, Quan-Chao; Jiang, Chen-Hui; Wu, Chao; Ma, Guang-Yao; Zhao, Xing; Zong, Zhi-Min; Sun, Shi-Gang

2014-06-07

A facile bottom-up strategy was developed to fabricate nitrogen-doped graphene sheets (NGSs) from glucose using a sacrificial template synthesis method. Three main types of nitrogen dopants (pyridinic, pyrrolic and graphitic nitrogens) were introduced into the graphene lattice, and an inimitable microporous structure of NGS with a high specific surface area of 504 m(2) g(-1) was obtained. Particularly, with hybrid features of lithium ion batteries and Faradic capacitors at a low rate and features of Faradic capacitors at a high rate, the NGS presents a superior lithium storage performance. During electrochemical cycling, the NGS electrode afforded an enhanced reversible capacity of 832.4 mA h g(-1) at 100 mA g(-1) and an excellent cycling stability of 750.7 mA h g(-1) after 108 discharge-charge cycles. Furthermore, an astonishing rate capability of 333 mA h g(-1) at 10,000 mA g(-1) and a high rate cycle performance of 280.6 mA h g(-1) even after 1200 cycles were also achieved, highlighting the significance of nitrogen doping on the maximum utilization of graphene-based materials for advanced lithium storage.
From nanoscale to macroscale: Engineering biomass derivatives with nitrogen doping for tailoring dielectric properties and electromagnetic absorption

Science.gov (United States)

Wang, Yana; Zhou, Zhili; Chen, Mingji; Huang, Yixing; Wang, Changxian; Song, Wei-Li

2018-05-01

Since achievement in electromagnetic (EM) technology dramatically promotes the critical requirement in developing advanced EM response materials, which are required to hold various advantageous features in light weight, small thickness, strong reflection loss and broadband absorption, the most important requirements, i.e. strong reflection loss and broadband absorption, are still highly pursued because of the intrinsic shortage in conventional EM absorbers. For addressing such critical problems, a unique three-dimensional nitrogen doped carbon monolith was demonstrated to understand the effects of the nitrogen doping on the dielectric and microwave absorption performance. The chemical components of the nitrogen doped carbon monoliths have been quantitatively determined for fully understanding the effects of nanoscale structures on the macroscopic composites. A modified Cole-Cole plot is plotted for guiding the chemical doping and material process, aiming to realizing the best matching conditions. The results have promised a universal route for achieving advanced materials with strong and broadband EM absorption.
Nitrogen doping efficiency during vapor phase epitaxy of 4H-SiC

Energy Technology Data Exchange (ETDEWEB)

Rowland, L.B.; Brandt, C.D. [Northrop Grumman Science and Technology Center, Pittsburgh, PA (United States); Burk, A.A. Jr. [Northrop Grumman Advanced Technology Lab., Baltimore, MD (United States)

1998-06-01

This work examines the interrelationships among doping efficiency, mole fraction, and Si/C ratio for intentional doping of 4H-SiC during vapor phase epitaxy using N{sub 2}. For four Si/C ratios, the doping concentration increased linearly as a function of increasing N{sub 2} partial pressure with a slope of 1.0 {+-} 0.03. Variation of propane mole fraction while the SiH{sub 4} and N{sub 2} mole fractions were kept constant revealed two different modes of nitrogen incorporation, corresponding to carbon-rich and silicon-rich conditions. (orig.) 14 refs.
Interference effects on the photoionization cross sections between two neighbouring atoms: nitrogen as an example

International Nuclear Information System (INIS)

Jian-Hua, Wu; Jian-Min, Yuan

2009-01-01

Interference effects on the photoionization cross sections between two neighbouring atoms are considered based on the coherent scattering of the ionized electrons by the two nuclei when their separation is less than or comparable to the de Broglie wave length of the ionized electrons. As an example, the single atomic nitrogen ionization cross section and the total cross sections of two nitrogen atoms with coherently added photoionization amplitudes are calculated from the threshold to about 60 Å (1 Å = 0.1 nm) of the photon energy. The photoionization cross sections of atomic nitrogen are obtained by using the close-coupling R-matrix method. In the calculation 19 states are included. The ionization energy of the atomic nitrogen and the photoionization cross sections agree well with the experimental results. Based on the R-matrix results of atomic nitrogen, the interference effects between two neighbouring nitrogen atoms are obtained. It is shown that the interference effects are considerable when electrons are ionized just above the threshold, even for the separations between the two atoms are larger than two times of the bond length of N 2 molecules. Therefore, in hot and dense samples, effects caused by the coherent interference between the neighbours are expected to be observable for the total photoionization cross sections. (atomic and molecular physics)
Ferromagnetism in Fe-doped transition metal nitrides

Science.gov (United States)

Sharma, Ramesh; Sharma, Yamini

2018-04-01

Early transition metal mononitrides ScN and YN are refractory compounds with high hardness and melting points as well semiconducting properties. The presence of nitrogen vacancies in ScN/YN introduces asymmetric peaks in the density of states close to Fermi level, the same effects can be achieved by doping by Mn or Fe-atoms. Due to the substitution of TM atoms at Sc/Y sites, it was found that the p-d hybridization induces small magnetic moments at both Sc/Y and N sites giving rise to magnetic semiconductors (MS). From the calculated temperature dependent transport properties, the power factor and ZT is found to be lowered for doped ScN whereas it increases for doped YN. It is proposed that these materials have promising applications as spintronics and thermoelectric materials.
Phase stability and lattice thermal conductivity reduction in CoSb{sub 3} skutterudites, doped with chalcogen atoms

Energy Technology Data Exchange (ETDEWEB)

Battabyal, M., E-mail: manjusha.battabyal@project.arci.res.in; Priyadarshini, B.; Gopalan, R. [International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), IIT M Research Park, Taramani, Chennai-600113 (India); Pradipkanti, L.; Satapathy, Dillip K. [Department of Physics, Indian Institute of Technology Madras, Chennai-600036 (India)

2016-07-15

We report a significant reduction in the lattice thermal conductivity of the CoSb{sub 3} skuttertudites, doped with chalcogen atoms. Te/Se chalcogen atoms doped CoSb{sub 3} skutterudite samples (Te{sub 0.1}Co{sub 4}Sb{sub 12}, Se{sub 0.1}Co{sub 4}Sb{sub 12}, Te{sub 0.05}Se{sub 0.05}Co{sub 4}Sb{sub 12}) are processed by ball milling and spark plasma sintering. X-ray diffraction data combined with energy dispersive X-ray spectra indicate the doping of Te/Se chalcogen atoms in the skutterudite. The temperature dependent X-ray diffraction confirms the stability of the Te/Se doped CoSb{sub 3} skutterudite phase and absence of any secondary phase in the temperature range starting from 300 K to 773 K. The Raman spectroscopy reveals that different chalcogen dopant atoms cause different resonant optical vibrational modes between the dopant atom and the host CoSb{sub 3} skutterudite lattice. These optical vibrational modes do scatter heat carrying acoustic phonons in a different spectral range. It was found that among the Te/Se chalcogen atoms, Te atoms alter the host CoSb{sub 3} skutterudite lattice vibrations to a larger extent than Se atoms, and can potentially scatter more Sb related acoustic phonons. The Debye model of lattice thermal conductivity confirms that the resonant phonon scattering has important contributions to the reduction of lattice thermal conductivity in CoSb{sub 3} skutterudites doped with Te/Se chalcogen atoms. Lattice thermal conductivity ∼ 0.9 W/mK at 773 K is achieved in Te{sub 0.1}Co{sub 4}Sb{sub 12} skutterudites, which is the lowest value reported so far in CoSb{sub 3} skutterudites, doped with single Te chalcogen atom.
Hydrothermal Synthesis of Nitrogen-Doped Titanium Dioxide and Evaluation of Its Visible Light Photocatalytic Activity

Directory of Open Access Journals (Sweden)

Junjie Qian

2012-01-01

Full Text Available Nitrogen-doped titanium dioxide (N-doped TiO2 photocatalyst was synthesized from nanotube titanic acid (denoted as NTA; molecular formula H2Ti2O5·H2O precursor via a hydrothermal route in ammonia solution. As-synthesized N-doped TiO2 catalysts were characterized by means of X-ray diffraction, transmission electron microscopy, diffuse reflectance spectrometry, X-ray photoelectron spectroscopy, electron spin resonance spectrometry and Fourier transform infrared spectrometry. It was found that nanotube ammonium titanate (NAT was produced as an intermediate during the preparation of N-doped TiO2 from NTA, as evidenced by the N1s X-ray photoelectron spectroscopic peak of NH4 + at 401.7 eV. The catalyst showed much higher activities to the degradation of methylene blue and p-chlorophenol under visible light irradiation than Degussa P25. This could be attributed to the enhanced absorption of N-doped TiO2 in visible light region associated with the formation of single-electron-trapped oxygen vacancies and the inhibition of recombination of photo-generated electron-hole pair by doped nitrogen.
Synthesis of 2D Nitrogen-Doped Mesoporous Carbon Catalyst for Oxygen Reduction Reaction

Directory of Open Access Journals (Sweden)

Zhipeng Yu

2017-02-01

Full Text Available 2D nitrogen-doped mesoporous carbon (NMC is synthesized by using a mesoporous silica film as hard template, which is then investigated as a non-precious metal catalyst for the oxygen reduction reaction (ORR. The effect of the synthesis conditions on the silica template and carbon is extensively investigated. In this work, we employ dual templates—viz. graphene oxide and triblock copolymer F127—to control the textural features of a 2D silica film. The silica is then used as a template to direct the synthesis of a 2D nitrogen-doped mesoporous carbon. The resultant nitrogen-doped mesoporous carbon is characterized by transmission electron microscopy (TEM, nitrogen ad/desorption isotherms, X-ray photoelectron spectroscopy (XPS, cyclic voltammetry (CV, and rotating disk electrode measurements (RDE. The electrochemical test reveals that the obtained 2D-film carbon catalyst yields a highly electrochemically active surface area and superior electrocatalytic activity for the ORR compared to the 3D-particle. The superior activity can be firstly attributed to the difference in the specific surface area of the two catalysts. More importantly, the 2D-film morphology makes more active sites accessible to the reactive species, resulting in a much higher utilization efficiency and consequently better activity. Finally, it is noted that all the carbon catalysts exhibit a higher ORR activity than a commercial Pt catalyst, and are promising for use in fuel cells.
High performance supercapacitor using N-doped graphene prepared via supercritical fluid processing with an oxime nitrogen source

International Nuclear Information System (INIS)

Balaji, S. Suresh; Elavarasan, A.; Sathish, M.

2016-01-01

Graphical abstract: N-doped graphene prepared via supercritical fluid processing with oxime nitrogen source (DMG) showed enhanced performance in electrochemical supercapacitor application. A maximum specific capacitance of 286 F g"−"1 at a current density of 0.5 A/g was achieved with a high specific capacity retention of 98% after 1000 cycles at 5 A/g. - Highlights: • N-functionalised graphene synthesized via supercritical fluid processing. • DMG, an oxime based nitrogen precursor. • Maximum specific capacitance of 286 F/g at 0.5 A/g in aqueous solution. • Pyridinic as well as quarternary nitrogen for enhanced capacitance. - Abstract: Heteroatom doped graphene has been proved for its promising applications in electrochemical energy storage systems. Here, nitrogen (N) doped graphene was prepared via two different techniques namely supercritical fluid assisted processing and hydrothermal heat treatment using dimethylglyoxime (DMG) as an oxime nitrogen precursor. The FT-IR and Raman spectra showed the N-containing functional group in the graphene. The XRD analysis revealed the complete reduction of graphene oxide during the supercritical fluid processing. The elemental analysis and X-ray photoelectron spectroscopy revealed the amount and nature of N-doping in the graphene, respectively. The surface morphology and physical nature of the samples were analyzed using scanning and transmission electron microscopic analysis. The electrochemical performance of prepared electrode materials was evaluated using cyclic voltammetry, galvanostatic charge-discharge analysis and electrochemical impedance spectroscopy. The N-doped graphene prepared via supercritical fluid assisted processing exhibit enhanced capacitive behaviour with a maximum specific capacitance of 286 F g"−"1 at a current density of 0.5 A/g. The cycling studies showed 98% specific capacity retention with 100% coulombic efficiency over 1000 cycles at 5 A/g. The enhanced specific capacitance of N-doped
Synergistically enhanced activity of nitrogen-doped carbon dots/graphene composites for oxygen reduction reaction

Science.gov (United States)

Liu, Hui; Zhao, Qingshan; Liu, Jingyan; Ma, Xiao; Rao, Yuan; Shao, Xiaodong; Li, Zhongtao; Wu, Wenting; Ning, Hui; Wu, Mingbo

2017-11-01

With rapid dissociative adsorption of oxygen, nitrogen-doped carbon nanomaterials have been demonstrated to be efficient alternative catalysts for oxygen reduction reaction (ORR) in fuel cells. Herein, we developed a mild hydrothermal strategy to construct nitrogen-doped carbon dots/graphene (NCDs-NG) composites towards ORR. Carbon dots (CDs) were derived from petroleum coke via acid oxidation while graphene oxide (GO) was obtained from graphite by modified Hummer's method. Graphene was employed as a conductive substrate to disperse CDs during hydrothermal reducing reaction while ammonia was utilized as N source to dope both graphene and CDs. The synergistic effects, i.e. CDs as pillars for graphene and catalytic sites for ORR, the high conductivity of graphene, the quick O2 adsorption on doped pyridinic nitrogen endow the NCDs-NG composites with enhanced ORR catalytic performance in alkaline electrolyte. The onset potential of -95 mV and kinetic current density of 12.7 mA cm-2 at -0.7 V (vs. Ag/AgCl) can be compared to those of the commercial 20 wt% Pt/C catalyst. The electron transfer number is about 3.9, revealing a four-electron pathway for ORR. The optimal NCDs-NG catalyst shows superior durability and methanol tolerance than 20 wt% Pt/C. This work demonstrates a feasible and effective strategy to prepare metal-free efficient ORR electrocatalysts for fuel cell applications.
Nitrogen doped graphene supported palladium-cobalt as a promising catalyst for methanol oxidation reaction: Synthesis, characterization and electrocatalytic performance

International Nuclear Information System (INIS)

Kiyani, Roya; Rowshanzamir, Soosan; Parnian, Mohammad Javad

2016-01-01

In this work, palladium and palladium-cobalt supported on nitrogen doped graphene as anode materials in direct methanol fuel cells is reported. A simple and low temperature solvothermal method is used to directly prepare nanoflower-like NG and then, Pd and Pd−Co nanoparticles are precipitated onto the surface of NG using a modified polyol reduction method. The synthesized electrocatalysts are characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) are used to measure electrocatalytic methanol oxidation activity and the durability of electrocatalysts. The results show that Pd−Co/NG has better electrocatalytic activity than Pd/NG toward methanol oxidation reaction (MOR) in alkaline media that is related at the presence of cobalt atoms. In addition, chronoamperometric results indicate that Pd−Co/NG is more stable than commercial Pt/C for MOR. - Highlights: • Nitrogen doped graphene (NG) was prepared by a simple solvothermal method. • Pd and Pd−Co nanoparticles were deposited on NG by polyol reduction method. • Promoting effects of cobalt over Pd/NG for MOR were investigated. • Higher activity and enhanced durability was observed for Pd−Co/NG catalyst.
Nitrogen-doped hierarchical lamellar porous carbon synthesized from the fish scale as support material for platinum nanoparticle electrocatalyst toward the oxygen reduction reaction.

Science.gov (United States)

Liu, Haijing; Cao, Yinliang; Wang, Feng; Huang, Yaqin

2014-01-22

Novel hierarchical lamellar porous carbon (HLPC) with high BET specific surface area of 2730 m(2) g(-1) and doped by nitrogen atoms has been synthesized from the fish scale without any post-synthesis treatment, and applied to support the platinum (Pt) nanoparticle (NP) catalysts (Pt/HLPC). The Pt NPs could be highly dispersed on the porous surface of HLPC with a narrow size distribution centered at ca. 2.0 nm. The results of the electrochemical analysis reveal that the electrochemical active surface area (ECSA) of Pt/HLPC is larger than the Pt NP electrocatalyst supported on the carbon black (Pt/Vulcan XC-72). Compared with the Pt/Vulcan XC-72, the Pt/HLPC exhibits larger current density, lower overpotential, and enhanced catalytic activity toward the oxygen reduction reaction (ORR) through the direct four-electron pathway. The improved catalytic activity is mainly attributed to the high BET specific surface area, hierarchical porous structures and the nitrogen-doped surface property of HLPC, indicating the superiority of HLPC as a promising support material for the ORR electrocatalysts.
Application of nitrogen-doped TiO2 nano-tubes in dye-sensitized solar cells

DEFF Research Database (Denmark)

Tran, Vy Anh; Thinh Troung, Trieu; Pham Phan, Thu Anh

2017-01-01

Our research aimed to improve the overall energy conversion efficiency of DSCs by applying nitrogen-doped TiO2 nano-tubes (N-TNT) for the preparation of DSCs photo-anodes. The none-doped TiO2 nano-tubes (TNTs) were synthesized by alkaline hydrothermal treatment of Degussa P25 TiO2 particles in 10...
Synthesis of Nitrogen-Doped Carbon Nano tubes Using Injection-Vertical Chemical Vapor Deposition: Effects of Synthesis Parameters on the Nitrogen Content

International Nuclear Information System (INIS)

Hachimi, A.; Hakeem, A.; Merzougui, B.; Atieh, M. A.; Merzougui, B.; Atieh, M. A.; Laoui, A.; Swain, G.M.; Chang, Q.; Shao, M.

2015-01-01

Nitrogen-doped CNTs (N-CNTs) were synthesized using an injection-vertical chemical vapor deposition (IV-CVD) reactor. This type of reactor is quite useful for the continuous mass production of CNTs. In this work, the optimum deposition conditions for maximizing the incorporation of nitrogen were identified. Ferrocene served as the source of the Fe catalyst and was dissolved in acetonitrile, which served as both the hydrocarbon and nitrogen sources. Different concentrations of ferrocene in acetonitrile were introduced into the top of a vertically aligned reactor at a constant flow rate with hydrogen serving as the carrier. The effects of hydrogen flow rate, growth temperature, and catalyst loading (Fe from the ferrocene) on the microstructure, elemental composition, and yield of N-CNTs were investigated. The N-CNTs possessed a bamboo-like microstructure with a nitrogen doping level as high as 14 at.% when using 2.5 to 5 mg/m L of the ferrocene/acetonitrile mixture at 800 degree under a 1000 sccm flow of hydrogen. A production rate of 100 mg/h was achieved under the optimized synthesis conditions.
Simulation of N-atom production in dielectric-barrier discharge in nitrogen at atmospheric pressure

International Nuclear Information System (INIS)

Tsyganov, Dmitry; Pancheshnyi, Sergey

2012-01-01

A plasma-chemical model of atomic nitrogen production in a Townsend dielectric-barrier discharge in nitrogen at atmospheric pressure is presented. On the basis of the comparison with measured densities, a significant discrepancy between the calculated and the measured production rate of nitrogen atoms is observed and discussed. (paper)
Commercial and home-made nitrogen modified titanias. A short reflection about the advantageous/disadvantageous properties of nitrogen doping in the frame of their applicability

Science.gov (United States)

Pap, Zs.; Mogyorósi, K.; Veréb, G.; Dombi, A.; Hernádi, K.; Danciu, V.; Baia, L.

2014-09-01

As visible light driven photocatalysis became more and more intensively studied, the first commercial products showed up on the market. Simultaneously controversial results appeared in the literature generating an intensive debate regarding the advantages and draw-backs of nitrogen doping of titania. Hence, the present work focuses on two commercially available and four sol-gel made nitrogen modified titania powders regarding their structure and activity. It is demonstrated that the interstitial nitrogen entities “leak out” from the catalysts if the material is irradiated with UV light, while substitutional nitrogen remains stable. However, the latter one was proven to be less important in the photocatalytic point of view. These observations were also valid in the case of sol-gel made nitrogen modified titanias. Furthermore, the results obtained after applying different spectroscopic methods (IR, XPS and DRS) shown that the yellow color of the titanias, does not necessary mean that a successful doping is achieved.
Production mechanism of atomic nitrogen in atmospheric pressure pulsed corona discharge measured using two-photon absorption laser-induced fluorescence

International Nuclear Information System (INIS)

Teramoto, Yoshiyuki; Ono, Ryo; Oda, Tetsuji

2012-01-01

To study the production mechanism of atomic nitrogen, the temporal profile and spatial distribution of atomic nitrogen are measured in atmospheric pressure pulsed positive corona discharge using two-photon absorption laser-induced fluorescence. The absolute atomic nitrogen density in the streamer filaments is estimated from decay rate of atomic nitrogen in N 2 discharge. The results indicate that the absolute atomic nitrogen density is approximately constant against discharge energy. When the discharge voltage is 21.5 kV, production yield of atomic nitrogen produced by an N 2 discharge pulse is estimated to be 2.9 - 9.8 × 10 13 atoms and the energy efficiency of atomic nitrogen production is estimated to be about 1.8 - 6.1 × 10 16 atoms/J. The energy efficiency of atomic nitrogen production in N 2 discharge is constant against the discharge energy, while that in N 2 /O 2 discharge increases with discharge energy. In the N 2 /O 2 discharge, two-step process of N 2 dissociation plays significant role for atomic nitrogen production.
Synthesis of Nitrogen-Doped Carbon Nanotubes Using Injection-Vertical Chemical Vapor Deposition: Effects of Synthesis Parameters on the Nitrogen Content

Directory of Open Access Journals (Sweden)

Abdouelilah Hachimi

2015-01-01

Full Text Available Nitrogen-doped CNTs (N-CNTs were synthesized using an injection-vertical chemical vapor deposition (IV-CVD reactor. This type of reactor is quite useful for the continuous mass production of CNTs. In this work, the optimum deposition conditions for maximizing the incorporation of nitrogen were identified. Ferrocene served as the source of the Fe catalyst and was dissolved in acetonitrile, which served as both the hydrocarbon and nitrogen sources. Different concentrations of ferrocene in acetonitrile were introduced into the top of a vertically aligned reactor at a constant flow rate with hydrogen serving as the carrier. The effects of hydrogen flow rate, growth temperature, and catalyst loading (Fe from the ferrocene on the microstructure, elemental composition, and yield of N-CNTs were investigated. The N-CNTs possessed a bamboo-like microstructure with a nitrogen doping level as high as 14 at.% when using 2.5 to 5 mg/mL of the ferrocene/acetonitrile mixture at 800°C under a 1000 sccm flow of hydrogen. A production rate of 100 mg/h was achieved under the optimized synthesis conditions.
The charge-transfer property and the performance of dye-sensitized solar cells of nitrogen doped zinc oxide

Energy Technology Data Exchange (ETDEWEB)

Zhang Lingyun [Department of Chemistry, Harbin Institute of Technology, Harbin 150001 (China); School of Chemical Engineering, Northeast Dianli University, Jilin 132012 (China); Yang Yulin, E-mail: ylyang@hit.edu.cn [Department of Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Fan Ruiqing, E-mail: fanruiqing@hit.edu.cn [Department of Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Chen Haiyan [Department of Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Jia Ruokun [School of Chemical Engineering, Northeast Dianli University, Jilin 132012 (China); Wang Yonghui [Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China); Ma Liqun; Wang Yazhen [School of Material Science of Engineering, Qiqihar University, Qiqihar 161006 (China)

2012-07-25

Highlights: Black-Right-Pointing-Pointer Two methods (the solution and annealing methods) are used to prepare nitrogen-doped ZnO. Black-Right-Pointing-Pointer The charge-transfer properties of N-doping ZnO are investigated. Black-Right-Pointing-Pointer The overall conversion efficiency of N-doped ZnO-based dye-sensitized solar cells is successfully improved by N doping. - Abstract: In this study two methods, namely the solution and annealing methods, were used to prepare nitrogen-doped ZnO. The X-ray photoelectron spectroscopy (XPS) was performed to identify the composition and chemical states of N-doped ZnO. The N doping by the solution method was found to effectively decrease the acceptor effects. Surface photovoltage measurements (SPS) revealed a redshift of the threshold wavelength for the N-doped ZnO. And the recombination of photoinduced electron-hole pairs in this semiconductor material was obviously suppressed. The N-doped ZnO (solution method) exhibits the best performances among all the materials, even superior to N-doped ZnO (annealing method). Its J{sub sc} and {eta} values (9.35 mA/cm{sup 2} and 2.64%) have enhanced by several times compared with un-doped ZnO (J{sub sc}, 2.85 mA/cm{sup 2}; {eta}, 0.67%). The overall conversion efficiency of ZnO-based dye-sensitized solar cells was successfully improved by the N doping.

The charge-transfer property and the performance of dye-sensitized solar cells of nitrogen doped zinc oxide

International Nuclear Information System (INIS)

Zhang Lingyun; Yang Yulin; Fan Ruiqing; Chen Haiyan; Jia Ruokun; Wang Yonghui; Ma Liqun; Wang Yazhen

2012-01-01

Highlights: ► Two methods (the solution and annealing methods) are used to prepare nitrogen-doped ZnO. ► The charge-transfer properties of N-doping ZnO are investigated. ► The overall conversion efficiency of N-doped ZnO-based dye-sensitized solar cells is successfully improved by N doping. - Abstract: In this study two methods, namely the solution and annealing methods, were used to prepare nitrogen-doped ZnO. The X-ray photoelectron spectroscopy (XPS) was performed to identify the composition and chemical states of N-doped ZnO. The N doping by the solution method was found to effectively decrease the acceptor effects. Surface photovoltage measurements (SPS) revealed a redshift of the threshold wavelength for the N-doped ZnO. And the recombination of photoinduced electron–hole pairs in this semiconductor material was obviously suppressed. The N-doped ZnO (solution method) exhibits the best performances among all the materials, even superior to N-doped ZnO (annealing method). Its J sc and η values (9.35 mA/cm 2 and 2.64%) have enhanced by several times compared with un-doped ZnO (J sc , 2.85 mA/cm 2 ; η, 0.67%). The overall conversion efficiency of ZnO-based dye-sensitized solar cells was successfully improved by the N doping.
Complex Boron Redistribution in P+ Doped-polysilicon / Nitrogen Doped Silicon Bi-layers during Activation Annealing

Science.gov (United States)

Abadli, S.; Mansour, F.; Perrera, E. Bedel

We have investigated and modeled the complex phenomenon of boron (B) redistribution process in strongly doped silicon bilayers structure. A one-dimensional two stream transfer model well adapted to the particular structure of bi- layers and to the effects of strong-concentrations has been developed. This model takes into account the instantaneous kinetics of B transfer, trapping, clustering and segregation during the thermal B activation annealing. The used silicon bi-layers have been obtained by low pressure chemical vapor deposition (LPCVD) method, using in-situ nitrogen- doped-silicon (NiDoS) layer and strongly B doped polycrystalline-silicon (P+) layer. To avoid long redistributions, thermal annealing was carried out at relatively lowtemperatures (600 °C and 700 °C) for various times ranging between 30 minutes and 2 hours. The good adjustment of the simulated profiles with the experimental secondary ion mass spectroscopy (SIMS) profiles allowed a fundamental understanding about the instantaneous physical phenomena giving and disturbing the complex B redistribution profiles-shoulders kinetics.
High-Surface-Area Nitrogen-Doped Reduced Graphene Oxide for Electric Double-Layer Capacitors.

Science.gov (United States)

Youn, Hee-Chang; Bak, Seong-Min; Kim, Myeong-Seong; Jaye, Cherno; Fischer, Daniel A; Lee, Chang-Wook; Yang, Xiao-Qing; Roh, Kwang Chul; Kim, Kwang-Bum

2015-06-08

A two-step method consisting of solid-state microwave irradiation and heat treatment under NH3 gas was used to prepare nitrogen-doped reduced graphene oxide (N-RGO) with a high specific surface area (1007 m(2) g(-1) ), high electrical conductivity (1532 S m(-1) ), and low oxygen content (1.5 wt %) for electrical double-layer capacitor applications. The specific capacitance of N-RGO was 291 F g(-1) at a current density of 1 A g(-1) , and a capacitance of 261 F g(-1) was retained at 50 A g(-1) , which indicated a very good rate capability. N-RGO also showed excellent cycling stability and preserved 96 % of the initial specific capacitance after 100 000 cycles. Near-edge X-ray absorption fine-structure spectroscopy results provided evidenced for the recovery of π conjugation in the carbon networks with the removal of oxygenated groups and revealed chemical bonding of the nitrogen atoms in N-RGO. The good electrochemical performance of N-RGO is attributed to its high surface area, high electrical conductivity, and low oxygen content. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Synthesis of diamonds in Fe–C systems using nitrogen and hydrogen co-doped impurities under HPHT

International Nuclear Information System (INIS)

Sun Shi-Shuai; Xu Zhi-Hui; Cui Wen; Jia Xiao-Peng; Ma Hong-An

2017-01-01

In this study, we investigate the effect of nitrogen and hydrogen impurities on colors, morphologies, impurity structures and synthesis conditions of diamond crystals in Fe–C systems with C 3 N 6 H 6 additives at pressures in the range 5.0–6.5 GPa and temperatures of 1400–1700 °C in detail. Our results reveal that the octahedron diamond nucleation in a Fe–C system is evidently inhibited by co-doped N–H elements, thereby resulting in the increase of minimum pressure and temperature of diamond synthesis by spontaneous nucleation. The octahedron diamond crystals synthesized from a pure Fe–C system are colorless, while they become green in the system with C 3 N 6 H 6 additive. The surface defects of diamond will deteriorate when the nitrogen and hydrogen atoms simultaneously incorporate in the diamond growth environment in the Fe–C system. We believe that this study will provide some important information and be beneficial for the deep understanding of the crystallization of diamonds from different component systems. (paper)
Effect of nitrogen doping on the thermal conductivity of GeTe thin films

Energy Technology Data Exchange (ETDEWEB)

Fallica, Roberto; Longo, Massimo; Wiemer, Claudia [Laboratorio MDM, IMM-CNR, Agrate Brianza (Italy); Varesi, Enrico; Fumagalli, Luca; Spadoni, Simona [Micron Semiconductor Italia, Agrate Brianza (Italy)

2013-12-15

The 3{omega} method was employed to determine the effect of nitrogen doping (5 at.%) on the thermal conductivity of sputtered thin films of stoichiometric GeTe (a material of interest for phase change memories). It was found that nitrogen doping has a detrimental effect on the thermal conductivity of GeTe in both phases, but less markedly in the amorphous (-25%) than in the crystalline one (-40%). On the opposite, no effect could be detected on the measured thermal boundary resistance between these films and SiO{sub 2}, within the experimental error. Our results agree with those obtained by molecular dynamic simulation of amorphous GeTe. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Highly nitrogen-doped carbon capsules: scalable preparation and high-performance applications in fuel cells and lithium ion batteries.

Science.gov (United States)

Hu, Chuangang; Xiao, Ying; Zhao, Yang; Chen, Nan; Zhang, Zhipan; Cao, Minhua; Qu, Liangti

2013-04-07

Highly nitrogen-doped carbon capsules (hN-CCs) have been successfully prepared by using inexpensive melamine and glyoxal as precursors via solvothermal reaction and carbonization. With a great promise for large scale production, the hN-CCs, having large surface area and high-level nitrogen content (N/C atomic ration of ca. 13%), possess superior crossover resistance, selective activity and catalytic stability towards oxygen reduction reaction for fuel cells in alkaline medium. As a new anode material in lithium-ion battery, hN-CCs also exhibit excellent cycle performance and high rate capacity with a reversible capacity of as high as 1046 mA h g(-1) at a current density of 50 mA g(-1) after 50 cycles. These features make the hN-CCs developed in this study promising as suitable substitutes for the expensive noble metal catalysts in the next generation alkaline fuel cells, and as advanced electrode materials in lithium-ion batteries.
Room temperature ferromagnetism and absorption red-shift in nitrogen-doped TiO2 nanoparticles

International Nuclear Information System (INIS)

Gómez-Polo, C.; Larumbe, S.; Monge, M.

2014-01-01

Highlights: • N-doped TiO 2 anatase nanoparticles were obtained by sol–gel. • The nanoparticle size, controlled by the N doping, determines lattice parameters. • Correlation between room temperature ferromagnetism and absorption red-shift. • Oxygen vacancies reinforce both phenomena. • Metal transition impurities contribute to the room temperature ferromagnetism. - Abstract: In this work, room-temperature ferromagnetism and the red-shift of the optical absorption is analyzed in nitrogen doped TiO 2 semiconductor nanoparticles. The nanoparticles were synthesized by the sol–gel method using urea as the nitrogen source. Titanium Tetraisopropoxide (TTIP) was employed as the alkoxyde precursor and dissolved in ethanol. The as prepared gels were dried and calcined in air at 300 °C. Additionally, post-annealing treatments under vacuum atmosphere were performed to modify the oxygen stoichiometry of the samples. The anatase lattice parameters, analyzed by means of powder X-ray diffractometry, depend on the nanometer grain size of the nanoparticles (increase and decrease, respectively, of the tetragonal a and c lattice parameters with respect to the bulk values). The diffuse reflectance ultraviolet–visible (UV–Vis) absorbance spectra show a clear red-shift as consequence of the nitrogen and the occurrence of intragap energy levels. The samples display ferromagnetic features at room temperature that are reinforced with the nitrogen content and after the post annealings in vacuum. The results indicate a clear correlation between the room temperature ferromagnetism and the shift of the absorbance spectrum. In both phenomena, oxygen vacancies (either induced by the nitrogen doping or by the post vacuum annealings) play a dominant role. However, we conclude the existence of very low concentration of diluted transition metal impurities that determine the room ferromagnetic response (bound magnetic polaron BMP model). The contraction of the c soft axis of the
Ruthenium supported on nitrogen-doped carbon nanotubes for the oxygen reduction reaction in alkaline electrolyte; Poster

CSIR Research Space (South Africa)

Mabena, LF

2012-07-01

Full Text Available . Recently, several researchers have shown that nitrogen modified carbon nanotubes (CNTs) are good electrocatalyst supports and that they enhance the electrocatalytic activity for the ORR. Nitrogen-doped carbon nanotubes (N-CNTs) prepared via thermal chemical...
Three dimensional nitrogen-doped graphene aerogels functionalized with melamine for multifunctional applications in supercapacitors and adsorption

Energy Technology Data Exchange (ETDEWEB)

Xing, Ling-Bao; Hou, Shu-Fen; Zhou, Jin; Zhang, Jing-Li; Si, Weijiang; Dong, Yunhui, E-mail: hgxydyh@sdut.edu.cn; Zhuo, Shuping, E-mail: zhuosp_academic@yahoo.com

2015-10-15

In present work, we demonstrate an efficient and facile strategy to fabricate three-dimensional (3D) nitrogen-doped graphene aerogels (NGAs) based on melamine, which serves as reducing and functionalizing agent of graphene oxide (GO) in an aqueous medium with ammonia. Benefiting from well-defined and cross-linked 3D porous network architectures, the supercapacitor based on the NGAs exhibited a high specific capacitance of 170.5 F g{sup −1} at 0.2 A g{sup −1}, and this capacitance also showed good electrochemical stability and a high degree of reversibility in the repetitive charge/discharge cycling test. More interestingly, the prepared NGAs further exhibited high adsorption capacities and high recycling performance toward several metal ions such as Pb{sup 2+}, Cu{sup 2+} and Cd{sup 2+}. Moreover, the hydrophobic carbonized nitrogen-doped graphene aerogels (CNGAs) showed outstanding adsorption and recycling performance for the removal of various oils and organic solvents. - Graphical abstract: Three-dimensional nitrogen-doped graphene aerogels were prepared by using melamine as reducing and functionalizing agent in an aqueous medium with ammonia, which showed multifunctional applications in supercapacitors and adsorption. - Highlights: • Three-dimensional nitrogen-doped graphene aerogels (NGAs) were prepared. • Melamine was used as reducing and functionalizing agent. • NGAs exhibited relatively good electrochemical properties in supercapacitor. • NGAs exhibited high adsorption performance toward several metal ions. • CNGAs showed outstanding adsorption capacities for various oils and solvents.
Visible Light Irradiation-Mediated Drug Elution Activity of Nitrogen-Doped TiO2 Nano tubes

International Nuclear Information System (INIS)

Oh, S.; Moon, K.S.; Bae, J.M.; Moon, J.H.; Jin, S.

2013-01-01

We have developed nitrogen-doped TiO 2 nano tubes showing photo catalytic activity in the visible light region and have investigated the triggered release of antibiotics from these nano tubes in response to remote visible light irradiation. Scanning electron microscopy (SEM) observations indicated that the structure of TiO 2 nano tubes was not destroyed on the conditions of 0.05 and 0.1 M diethanolamine treatment. The results of X-ray photoelectron spectroscopy (XPS) confirmed that nitrogen, in the forms of nitrite (TiO 2 ) and nitrogen monoxide (NO), had been incorporated into the TiO 2 nano tube surface. A drug-release test revealed that the antibiotic-loaded TiO 2 nano tubes showed sustained and prolonged drug elution with the help of polylactic acid. Visible light irradiation tests showed that the antibiotic release from nitrogen-doped nano tubes was significantly higher than that from pure TiO 2 nano tubes (ρ ≨ 0.05).
Synthesis and Doping of Ligand-Protected Atomically-Precise Metal Nanoclusters

KAUST Repository

Aljuhani, Maha A.

2016-01-01

by controlling their size, shape, and composition. Among the most thriving areas of research about nanoparticle is the synthesis and doping of the ligand-protected atomically-precise metal nanoclusters. In this thesis, we developed three different novel metal
Effect of substrate temperature on corrosion performance of nitrogen doped amorphous carbon thin films in NaCl solution

Energy Technology Data Exchange (ETDEWEB)

Khun, N.W. [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Liu, E., E-mail: MEJLiu@ntu.edu.s [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

2009-07-01

Nitrogen doped amorphous carbon (a-C:N) thin films were deposited on p-Si substrates by DC magnetron sputtering at varying substrate temperature from room temperature (RT) to 300 {sup o}C. The bonding structure, surface morphology and adhesion strength of the a-C:N films were investigated by using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM) and micro-scratch testing. The corrosion behavior of the a-C:N films was evaluated by potentiodynamic polarization test in a 0.6 M NaCl solution. The results indicated that the corrosion resistance of the films depended on the sp{sup 3}-bonded cross-link structure that was significantly affected by the substrate temperature.
Effect of substrate temperature on corrosion performance of nitrogen doped amorphous carbon thin films in NaCl solution

International Nuclear Information System (INIS)

Khun, N.W.; Liu, E.

2009-01-01

Nitrogen doped amorphous carbon (a-C:N) thin films were deposited on p-Si substrates by DC magnetron sputtering at varying substrate temperature from room temperature (RT) to 300 o C. The bonding structure, surface morphology and adhesion strength of the a-C:N films were investigated by using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM) and micro-scratch testing. The corrosion behavior of the a-C:N films was evaluated by potentiodynamic polarization test in a 0.6 M NaCl solution. The results indicated that the corrosion resistance of the films depended on the sp 3 -bonded cross-link structure that was significantly affected by the substrate temperature.
A high-performance mesoporous carbon supported nitrogen-doped carbon electrocatalyst for oxygen reduction reaction

Science.gov (United States)

Xu, Jingjing; Lu, Shiyao; Chen, Xu; Wang, Jianan; Zhang, Bo; Zhang, Xinyu; Xiao, Chunhui; Ding, Shujiang

2017-12-01

Investigating low-cost and highly active electrocatalysts for oxygen reduction reactions (ORR) is of crucial importance for energy conversion and storage devices. Herein, we design and prepare mesoporous carbon supported nitrogen-doped carbon by pyrolysis of polyaniline coated on CMK-3. This electrocatalyst exhibits excellent performance towards ORR in alkaline media. The optimized nitrogen-doped mesoporous electrocatalyst show an onset potential (E onset) of 0.95 V (versus reversible hydrogen electrode (RHE)) and half-wave potential (E 1/2) of 0.83 V (versus RHE) in 0.1 M KOH. Furthermore, the as-prepared catalyst presents superior durability and methanol tolerance compared to commercial Pt/C indicating its potential applications in fuel cells and metal-air batteries.
Nitrogen Atom Energy Distributions in a Hollow-cathode Planar Sputtering Magnetron

International Nuclear Information System (INIS)

Ruzic, D.N.; Goeckner, M.J.; Cohen, S.A.; Wang, Zhehui

1999-01-01

Energy distributions of N atoms in a hollow-cathode planar sputtering magnetron were obtained by use of optical emission spectroscopy. A characteristic line, N I 8216.3 , well-separated from molecular nitrogen emission bands, was identified. Jansson's nonlinear spectral deconvolution method, refined by minimization of χ w ampersand sup2; , was used to obtain the optimal deconvolved spectra. These showed nitrogen atom energies from 1 eV to beyond 500 eV. Based on comparisons with VFTRIM results, we propose that the energetic N atoms are generated from N 2 + ions after these ions are accelerated through the sheath and dissociatively reflect from the cathode
Effect of substrate temperature on structural and optical properties of nitrogen doped SnO2 thin film

International Nuclear Information System (INIS)

Thakur, Anup; Kumar, Varinder; Kang, Se Jun; Lee, Ik-Jae; Gautam, Sanjeev; Chae, K. H.; Shin, Hyun Joon

2014-01-01

Nitrogen doped SnO 2 thin films (thickness ∼ 250 nm) were deposited at different substrate temperature by radio frequency (rf) sputtering method. Crystal structure, morphology and optical properties of these films were investigated by x-ray diffraction (XRD), atomic force microscopy (AFM) and UV-VIS-NIR spectrophotometer, respectively. XRD measurement suggests that the film deposited at room temperature was amorphous in nature and films deposited at higher temperature were crystalline in nature. The film deposited at RT and 200 °C have transparency more than 90% in visible region but the film deposited at 400 °C has lesser transparency. Red shift was observed in the absorption edge may be due to decrease in ionicity due to the formation of the Sn-N bond
Nitrogen-doped reduced graphene oxide electrodes for electrochemical supercapacitors.

Science.gov (United States)

Nolan, Hugo; Mendoza-Sanchez, Beatriz; Ashok Kumar, Nanjundan; McEvoy, Niall; O'Brien, Sean; Nicolosi, Valeria; Duesberg, Georg S

2014-02-14

Herein we use Nitrogen-doped reduced Graphene Oxide (N-rGO) as the active material in supercapacitor electrodes. Building on a previous work detailing the synthesis of this material, electrodes were fabricated via spray-deposition of aqueous dispersions and the electrochemical charge storage mechanism was investigated. Results indicate that the functionalised graphene displays improved performance compared to non-functionalised graphene. The simplicity of fabrication suggests ease of up-scaling of such electrodes for commercial applications.
En route to controlled catalytic CVD synthesis of densely packed and vertically aligned nitrogen-doped carbon nanotube arrays

Directory of Open Access Journals (Sweden)

Slawomir Boncel

2014-03-01

Full Text Available The catalytic chemical vapour deposition (c-CVD technique was applied in the synthesis of vertically aligned arrays of nitrogen-doped carbon nanotubes (N-CNTs. A mixture of toluene (main carbon source, pyrazine (1,4-diazine, nitrogen source and ferrocene (catalyst precursor was used as the injection feedstock. To optimize conditions for growing the most dense and aligned N-CNT arrays, we investigated the influence of key parameters, i.e., growth temperature (660, 760 and 860 °C, composition of the feedstock and time of growth, on morphology and properties of N-CNTs. The presence of nitrogen species in the hot zone of the quartz reactor decreased the growth rate of N-CNTs down to about one twentieth compared to the growth rate of multi-wall CNTs (MWCNTs. As revealed by electron microscopy studies (SEM, TEM, the individual N-CNTs (half as thick as MWCNTs grown under the optimal conditions were characterized by a superior straightness of the outer walls, which translated into a high alignment of dense nanotube arrays, i.e., 5 × 108 nanotubes per mm2 (100 times more than for MWCNTs grown in the absence of nitrogen precursor. In turn, the internal crystallographic order of the N-CNTs was found to be of a ‘bamboo’-like or ‘membrane’-like (multi-compartmental structure morphology. The nitrogen content in the nanotube products, which ranged from 0.0 to 3.0 wt %, was controlled through the concentration of pyrazine in the feedstock. Moreover, as revealed by Raman/FT-IR spectroscopy, the incorporation of nitrogen atoms into the nanotube walls was found to be proportional to the number of deviations from the sp2-hybridisation of graphene C-atoms. As studied by XRD, the temperature and the [pyrazine]/[ferrocene] ratio in the feedstock affected the composition of the catalyst particles, and hence changed the growth mechanism of individual N-CNTs into a ‘mixed base-and-tip’ (primarily of the base-type type as compared to the purely �
En route to controlled catalytic CVD synthesis of densely packed and vertically aligned nitrogen-doped carbon nanotube arrays.

Science.gov (United States)

Boncel, Slawomir; Pattinson, Sebastian W; Geiser, Valérie; Shaffer, Milo S P; Koziol, Krzysztof K K

2014-01-01

The catalytic chemical vapour deposition (c-CVD) technique was applied in the synthesis of vertically aligned arrays of nitrogen-doped carbon nanotubes (N-CNTs). A mixture of toluene (main carbon source), pyrazine (1,4-diazine, nitrogen source) and ferrocene (catalyst precursor) was used as the injection feedstock. To optimize conditions for growing the most dense and aligned N-CNT arrays, we investigated the influence of key parameters, i.e., growth temperature (660, 760 and 860 °C), composition of the feedstock and time of growth, on morphology and properties of N-CNTs. The presence of nitrogen species in the hot zone of the quartz reactor decreased the growth rate of N-CNTs down to about one twentieth compared to the growth rate of multi-wall CNTs (MWCNTs). As revealed by electron microscopy studies (SEM, TEM), the individual N-CNTs (half as thick as MWCNTs) grown under the optimal conditions were characterized by a superior straightness of the outer walls, which translated into a high alignment of dense nanotube arrays, i.e., 5 × 10(8) nanotubes per mm(2) (100 times more than for MWCNTs grown in the absence of nitrogen precursor). In turn, the internal crystallographic order of the N-CNTs was found to be of a 'bamboo'-like or 'membrane'-like (multi-compartmental structure) morphology. The nitrogen content in the nanotube products, which ranged from 0.0 to 3.0 wt %, was controlled through the concentration of pyrazine in the feedstock. Moreover, as revealed by Raman/FT-IR spectroscopy, the incorporation of nitrogen atoms into the nanotube walls was found to be proportional to the number of deviations from the sp(2)-hybridisation of graphene C-atoms. As studied by XRD, the temperature and the [pyrazine]/[ferrocene] ratio in the feedstock affected the composition of the catalyst particles, and hence changed the growth mechanism of individual N-CNTs into a 'mixed base-and-tip' (primarily of the base-type) type as compared to the purely 'base'-type for undoped
Biomass-Derived Oxygen and Nitrogen Co-Doped Porous Carbon with Hierarchical Architecture as Sulfur Hosts for High-Performance Lithium/Sulfur Batteries

Directory of Open Access Journals (Sweden)

Yan Zhao

2017-11-01

Full Text Available In this work, a facile strategy to synthesize oxygen and nitrogen co-doped porous carbon (ONPC is reported by one-step pyrolysis of waste coffee grounds. As-prepared ONPC possesses highly rich micro/mesopores as well as abundant oxygen and nitrogen co-doping, which is applied to sulfur hosts as lithium/sulfur batteries’ appropriate cathodes. In battery testing, the sulfur/oxygen and nitrogen co-doped porous carbon (S/ONPC composite materials reveal a high initial capacity of 1150 mAh·g−1 as well as a reversible capacity of 613 mAh·g−1 after the 100th cycle at 0.2 C. Furthermore, when current density increases to 1 C, a discharge capacity of 331 mAh·g−1 is still attainable. Due to the hierarchical porous framework and oxygen/nitrogen co-doping, the S/ONPC composite exhibits a high utilization of sulfur and good electrochemical performance via the immobilization of the polysulfides through strong chemical binding.

One pot synthesis of ilmenite-type NiMnO3-"nitrogen-doped" graphene nanocomposite as next generation supercapacitors.

Science.gov (United States)

Giri, Soumen; Ghosh, Debasis; Das, Chapal Kumar

2013-10-28

NiMnO3-nitrogen doped graphene composite has been synthesized by a simple hydrothermal method and its supercapacitor performance investigated. The composite exhibits a specific capacitance of 750.2 F g(-1) in 1 M Na2SO4 at a scan rate of 1 mV s(-1). Nitrogen insertion inside the carbon lattice plays a crucial role in the enhancement of the overall specific capacitance and its long-term stability. This reproducible and superior performance of NiMnO3-nitrogen doped graphene composite make it attractive as a candidate for energy storage materials.
One unit-cell seed layer induced epitaxial growth of heavily nitrogen doped anatase TiO{sub 2} films

Energy Technology Data Exchange (ETDEWEB)

Chen, T L; Hirose, Y; Hitosugi, T; Hasegawa, T [Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan)], E-mail: chen@ksp.or.jp

2008-03-21

We present a novel way to obtain heavily nitrogen doped anatase TiO{sub 2} films by using a solid-state nitrogen source. Epitaxial growth of the films was realized by introducing one unit-cell seed layer, which was indicated by reflection high-energy electron diffraction as intensity oscillation. Results of x-ray diffraction and x-ray photoelectron spectroscopy confirmed that the films were in the anatase phase heavily doped with nitrogen of {approx}15 at%. The films obtained exhibited considerable narrowing of the optical bandgap, resulting in an enhancement of absorption in the visible-light region. (fast track communication)
A highly efficient electrocatalyst for oxygen reduction reaction: phosphorus and nitrogen co-doped hierarchically ordered porous carbon derived from an iron-functionalized polymer

Science.gov (United States)

Deng, Chengwei; Zhong, Hexiang; Li, Xianfeng; Yao, Lan; Zhang, Huamin

2016-01-01

Heteroatom-doped carbon materials have shown respectable activity for the oxygen reduction reaction (ORR) in alkaline media. However, the performances of these materials are not satisfactory for energy conversion devices, such as fuel cells. Here, we demonstrate a new type of phosphorus and nitrogen co-doped hierarchically ordered porous carbon (PNHOPC) derived from an iron-functionalized mesoporous polymer through an evaporation-induced self-assembly process that simultaneously combines the carbonization and nitrogen doping processes. The soft template and the nitrogen doping process facilitate the formation of the hierarchically ordered structure for the PNHOPC. The catalyst possesses a large surface area (1118 cm2 g-1) and a pore volume of 1.14 cm3 g-1. Notably, it exhibits excellent ORR catalytic performance, superior stability and methanol tolerance in acidic electrolytes, thus making the catalyst promising for fuel cells. The correlations between the unique pore structure and the nitrogen and phosphorus configuration of the catalysts with high catalytic activity are thoroughly investigated.Heteroatom-doped carbon materials have shown respectable activity for the oxygen reduction reaction (ORR) in alkaline media. However, the performances of these materials are not satisfactory for energy conversion devices, such as fuel cells. Here, we demonstrate a new type of phosphorus and nitrogen co-doped hierarchically ordered porous carbon (PNHOPC) derived from an iron-functionalized mesoporous polymer through an evaporation-induced self-assembly process that simultaneously combines the carbonization and nitrogen doping processes. The soft template and the nitrogen doping process facilitate the formation of the hierarchically ordered structure for the PNHOPC. The catalyst possesses a large surface area (1118 cm2 g-1) and a pore volume of 1.14 cm3 g-1. Notably, it exhibits excellent ORR catalytic performance, superior stability and methanol tolerance in acidic
Effective visible light-active nitrogen and samarium co-doped BiVO4 for the degradation of organic pollutants

International Nuclear Information System (INIS)

Wang, Min; Niu, Chao; Liu, Jun; Wang, Qianwu; Yang, Changxiu; Zheng, Haoyan

2015-01-01

Nitrogen and samarium co-doped BiVO 4 (N–xSm–BiVO 4 ) nanoparticles were synthesized using a sol–gel method with a corn stem template. The physicochemical properties of the resultant N–xSm–BiVO 4 particles were characterized using various methods: XPS, XRD, SEM, BET, and UV–Vis DRS analyses. The visible-light photocatalytic activity was successfully demonstrated by degrading a model dye, namely, methyl orange. The dopant content was optimized, and the nitrogen and samarium co-doped BiVO 4 extended the light absorption spectrum toward the visible region, significantly enhancing the photodegradation of the model dye. The Sm and N co-doped BiVO 4 exhibited the highest photocatalytic activity compared to materials with a single dopant or no dopant. The significantly enhanced photocatalytic activity of the N–Sm co-doped BiVO 4 under visible-light irradiation can be attributed to the synergistic effects of the nitrogen and samarium. - Highlights: • The N–Sm codoped BiVO 4 were synthesized using a sol–gel method with a corn stem template. • The N and Sm codoped BiVO 4 has excellent photocatalytic activity of methyl orange degradation. • The maximum activity was observed when the molar ratio of Sm/Bi was 1.0. • The high photocatalytic activity was caused by the synergistic effects between N doping and Sm doping
Facile preparation of nitrogen-doped porous carbon from waste tobacco by a simple pre-treatment process and their application in electrochemical capacitor and CO2 capture

International Nuclear Information System (INIS)

Sha, Yunfei; Lou, Jiaying; Bai, Shizhe; Wu, Da; Liu, Baizhan; Ling, Yun

2015-01-01

Highlights: • A pre-treatment process is used to prepared N-doped carbon from waste biomass. • Waste tobaccos, which are limited for the disposal, are used as the raw materials. • The product shows a specific surface area and nitrogen content. • Its electrochemical performance is better than commercial activated carbon. • Its CO 2 sorption performance is also better than commercial activated carbon. - Abstract: Preparing nitrogen-doped porous carbons directly from waste biomass has received considerable interest for the purpose of realizing the atomic economy. In this study, N-doped porous carbons have been successfully prepared from waste tobaccos (WT) by a simple pre-treatment process. The sample calcinated at 700 °C (WT-700) shows a micro/meso-porous structures with a BET surface area of 1104 m 2 g −1 and a nitrogen content of ca. 19.08 wt.% (EDS). Performance studies demonstrate that WT-700 displays 170 F g −1 electrocapacitivity at a current density of 0.5 A g −1 (in 6 M KOH), and a CO 2 capacity of 3.6 mmol g −1 at 0 °C and 1 bar, and a selectivity of ca. 32 for CO 2 over N 2 at 25 °C. Our studies indicate that it is feasible to prepare N-enriched porous carbons from waste natural crops by a pre-treatment process for potential industrial application
Microporous MOFs Engaged in the Formation of Nitrogen-Doped Mesoporous Carbon Nanosheets for High-Rate Supercapacitors.

Science.gov (United States)

Hou, Ya-Nan; Zhao, Zongbin; Yu, Zhengfa; Zhang, Su; Li, Shaofeng; Yang, Juan; Zhang, Han; Liu, Chang; Wang, Zhiyu; Qiu, Jieshan

2018-02-21

Nitrogen-doped mesoporous carbon nanosheets (NMCS) have been fabricated from zinc-based microporous metal-organic frameworks (ZIF-8) by pyrolysis in a molten salt medium. The as-prepared NMCS exhibit significantly improved specific capacitance (NMCS-8: 232 F g -1 at 0.5 A g -1 ) and capacitance retention ratio (75.9 % at 50 A g -1 ) compared with the micropore-dominant nitrogen-doped porous carbon polyhedrons (NPCP-5: 178 F g -1 at 0.5 A g -1 , 15.9 % at 20 A g -1 ) obtained by direct pyrolysis of nanocrystalline ZIF-8. The excellent capacitive performance and high rate performance of the NMCS can be attributed to their unique combination of structure and composition, that is, the two-dimensional and hierarchically porous structure provides a short ion-transport pathway and facilitates the supply of electrolyte ions, and the nitrogen-doped polar surface improves the interface wettability when used as an electrode. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Nitrogen-doped graphene forests as electrodes for high-performance wearable supercapacitors

International Nuclear Information System (INIS)

Wang, Mei; Ma, Yifei

2017-01-01

Highlights: •N-doped graphene forest (GF) is successfully synthesized by in-situ PECVD process. •Morphology of N-doped GF electrode realizes a better in-plane electron transfer. •Areal and volumetric capacitances increase 26% and 89% by the N-doping of GF. •Energy and power densities increase 87% and 50% by the N-doping of GF. •The N-doped GF-based EDLC shows excellent bendability and reliable durability. -- Abstract: Recently, a graphene forest (GF) is synthesized by a plasma enhanced chemical vapor deposition (PECVD) process, which subverts the stereotyped morphology of vertical graphene. The GF is demonstrated to possess excellent performance in flexible and bendable electrical double-layer capacitors (EDLCs). In this work, synthesis process of the GF has been optimized and N-doped GF is successfully achieved by introducing NH 3 as the nitrogen precursor during the PECVD process. The N-doping obviously affects the morphology of the GF and the in-plane conductivity of GF is desirably enhanced. The specific area capacitances and volumetric capacitances of N-doped GF-based EDLC increases 26% and 89% in average, respectively, at different current densities compared with the non-doped GF-based EDLC. In addition, both the energy and power densities are improved, and impressively, the energy densities improve 87% by the N-doping of GF electrodes. The GF-based EDLC also provides the desirable stability that no degradation can be observed within 10,000 cycles. Finally, the flexible N-doped GF-based EDLC is also tested as a wearable supercapacitor, exhibiting no capacitance decrease under the dynamic bending situation. Our approach to synthesize the N-doped GF electrodes can achieve the fine-scale nano-structured GF electrodes and provide a new way forward for improved energy storage devices.
Improved Electrochemical Performance of LiFePO4@N-Doped Carbon Nanocomposites Using Polybenzoxazine as Nitrogen and Carbon Sources.

Science.gov (United States)

Wang, Ping; Zhang, Geng; Li, Zhichen; Sheng, Wangjian; Zhang, Yichi; Gu, Jiangjiang; Zheng, Xinsheng; Cao, Feifei

2016-10-03

Polybenzoxazine is used as a novel carbon and nitrogen source for coating LiFePO 4 to obtain LiFePO 4 @nitrogen-doped carbon (LFP@NC) nanocomposites. The nitrogen-doped graphene-like carbon that is in situ coated on nanometer-sized LiFePO 4 particles can effectively enhance the electrical conductivity and provide fast Li + transport paths. When used as a cathode material for lithium-ion batteries, the LFP@NC nanocomposite (88.4 wt % of LiFePO 4 ) exhibits a favorable rate performance and stable cycling performance.
Electronic and magnetic properties of 1T-HfS{sub 2} by doping transition-metal atoms

Energy Technology Data Exchange (ETDEWEB)

Zhao, Xu, E-mail: zhaoxu@htu.cn [College of Physics and Electronic Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Wang, Tianxing; Wang, Guangtao [College of Physics and Electronic Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Dai, Xianqi [College of Physics and Electronic Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Department of Physics, Zhengzhou Normal University, Zhengzhou, Henan 450044 (China); Xia, Congxin [College of Physics and Electronic Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Yang, Lin [School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang 453007 (China)

2016-10-15

Highlights: • Pristine 1T-HfS{sub 2} is a semiconductor with indirect gaps of 1.250 eV • Magnetism can be observed for V, Cr, Mn, Fe, Co, and Cu doping. • Strong p–d hybridization was found between TM 3d orbitals and S 3p orbitals. • V-doped 1T-HfS{sub 2} is ideal for spin injection. - Abstract: We explored the electronic and magnetic properties of 1T-HfS{sub 2} doped by transition metal (TM) atom using the first-principles calculation. We doped the transition metal atoms from the IIIB to VIB groups in nonmagnetic 1T-HfS{sub 2}. Numerical results show that the pristine 1T-HfS{sub 2} is a semiconductor with indirect gaps of 1.250 eV. Magnetism can be observed for V, Cr, Mn, Fe, Co, and Cu doping. The polarized charges mainly arise from the localized 3d electrons of the TM atom. The strong p–d hybridization was found between the 3d orbitals of TM and 3p orbitals of S. The substituted 1T-HfS{sub 2} can be a metal, semiconductor or half-metal. Analysis of the band structure and magnetic properties indicates that TM-doped HfS{sub 2} (TM = V, Fe, Cu) are promising systems to explore two-dimensional diluted magnetic semiconductors. The formation energy calculations also indicate that it is energetically favorable and relatively easier to incorporate transition metal atom into the HfS{sub 2} under S-rich experimental conditions. In contrast, V-doped HfS{sub 2} has relatively wide half-metallic gap and low formation energy. So V-doped 1T-HfS{sub 2} is ideal for spin injection, which is important for application in semiconductor spintronics.
Nitrogen-doped carbon based on peptides of hair as electrode materials for surpercapacitors

International Nuclear Information System (INIS)

Guo, Zihan; Zhou, Qingwen; Wu, Zhaojun; Zhang, Zhiguo; Zhang, Wen; Zhang, Yao; Li, Lijun; Cao, Zhenzhu; Wang, Hong; Gao, Yanfang

2013-01-01

Highlights: • Hair was directly carbonized by environmental and energy-saving methods. • Hair was utilized to prepare nitrogen-doped carbon materials for supercapacitor. • A new approache for preparing nitrogen-rich active carbon from biomass waste of hair-like precursor. • Hair-based carbon having a non-crystalline layered structure and excellent capacitive performance. -- Abstract: Hair, a high-nitrogen energetic material, is utilized as a precursor for nitrogen-doped porous carbon. The preparation procedures for obtaining carbon from hair are very simple, namely, reductant or deionized water activation process followed by hair carbonization under argon atmosphere at 800 °C for 2 h. The samples are characterized through scanning electron microscopy, transmission electron microscopy, X-ray diffraction, nitrogen adsorption, and X-ray photoelectron microscopy. The carbon samples are tested as electrode materials in supercapacitors in a three-electrode system. The carbon (soaked in deionized water at 80 °C) presents relatively low specific surface areas (441.34 m 2 g −1 ) and shows higher capacitance (154.5 F g −1 ) compared with nitrogen-free commercial activated carbons (134.5 F g −1 ) at 5 A g −1 . The capacitance remains at 130.5 F g −1 even when the current load is increased to 15 A g −1 . The capacitance loss is only 5% in 6 M KOH after 10,000 charge and discharge cycles at 5 A g −1 . It is the unique microstructure after activation processing and electroactive nitrogen functionalities that enable the carbon obtained through a simple, ecological, and economical process to be utilized as a potential electrode material for electrical double-layer capacitors
Adsorption configurations of two nitrogen atoms on graphene

International Nuclear Information System (INIS)

Rani, Babita; Jindal, V. K.; Dharamvir, Keya

2014-01-01

We present calculations for different possible configurations of two nitrogen adatoms on graphene using the code VASP, based on Density Functional Theory (DFT). Two N atoms adsorbed on the graphene sheet can share a bond in two ways. They take positions either just above two adjacent carbon atoms or they form a bridge across opposite bonds of a hexagon in the graphene sheet. Both these configurations result into structural distortion of the sheet. Another stable configuration involving two N atoms consists of an N 2 molecule which is physisorbed at a distance 3.69 Å on the graphene sheet. Two N atoms can also be adsorbed on alternate bridge sites of neighbouring hexagons of graphene. This configuration again leads to distortion of the sheet in perpendicular direction
Facile hydrothermal method for synthesizing nitrogen-doped graphene nanoplatelets using aqueous ammonia: dispersion, stability in solvents and thermophysical performances

Science.gov (United States)

Shafiah Shazali, Siti; Amiri, Ahmad; Zubir, Mohd. Nashrul Mohd; Rozali, Shaifulazuar; Zakuan Zabri, Mohd; Sabri, Mohd Faizul Mohd

2018-03-01

A simple and green approach has been developed to synthesize nitrogen-doped graphene nanoplatelets (N-doped GNPs) for mass production with a very high stability in different solvents e.g. water, ethylene glycol, methanol, ethanol, and 1-hexanol. The strategy is based on mild oxidation of GNPs using hydrogen peroxide and doping with nitrogen using hydrothermal process. The modification of N-doped GNPs was demonstrated by FTIR, TGA, XPS, Raman spectroscopy and high resolution-transmission electron microscope (HRTEM). Further study was carried out by using N-doped GNPs as an additive to prepare different colloidal dispersions. Water-based N-doped GNPs, methanol-based N-doped GNPs, ethanol-based N-doped GNPs, ethylene-glycol based N-doped GNPs and 1-hexanol-based N-doped GNPs dispersions at 0.01 wt.% shown great colloidal stabilities, indicating 17%, 29%, 33%, 18%, and 43% sedimentations after a 15-days period, respectively. The thermophysical properties e.g., viscosity and thermal conductivity of water-based N-doped GNP nanofluids were also evaluated for different weight concentrations of 0.100, 0.075, 0.050, and 0.025 wt.%. Through this, it is found that the obtained dispersions have great potential to be used as working fluids for industrial thermal systems.
Palladium on Nitrogen-Doped Mesoporous Carbon: A Bifunctional Catalyst for Formate-Based, Carbon-Neutral Hydrogen Storage.

Science.gov (United States)

Wang, Fanan; Xu, Jinming; Shao, Xianzhao; Su, Xiong; Huang, Yanqiang; Zhang, Tao

2016-02-08

The lack of safe, efficient, and economical hydrogen storage technologies is a hindrance to the realization of the hydrogen economy. Reported herein is a reversible formate-based carbon-neutral hydrogen storage system that is established over a novel catalyst comprising palladium nanoparticles supported on nitrogen-doped mesoporous carbon. The support was fabricated by a hard template method and nitridated under a flow of ammonia. Detailed analyses demonstrate that this bicarbonate/formate redox equilibrium is promoted by the cooperative role of the doped nitrogen functionalities and the well-dispersed, electron-enriched palladium nanoparticles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Synthesis of nitrogen-doped graphene–ZnS quantum dots composites with highly efficient visible light photodegradation

Energy Technology Data Exchange (ETDEWEB)

Jiang, Shu-Dong; Tang, Gang [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); Ma, Yi-Fei [CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026 (China); Hu, Yuan, E-mail: yuanhu@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, 166 Ren' ai Road, Suzhou, Jiangsu 215123 (China); Song, Lei [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China)

2015-02-01

Nitrogen-doped graphene–ZnS quantum dots (NG–ZnS QDs) were synthesized by a one-pot hydrothermal process using graphene oxide and [(Zn{sub 2}S{sub 2}) (pa)] nanosheets as precursors. The results demonstrated that ZnS QDs deposited on the surface of the nitrogen-doped graphene (NG). Combined with series of our analysis and characterization, we found that [(Zn{sub 2}S{sub 2}) (pa)] nanosheets were used not only as the sources of ZnS QDs but also as the sources of nitrogen. Moreover, photocatalytic experiment of NG–ZnS QDs for organic dyes was conducted under visible light irradiation, and the results exhibited that the photocatalytic activities of resultant composites could be remarkably enhanced. This simple and catalyst-free approach for depositing ZnS QDs onto NG may provide an alternative way for preparation of other composites based on NG under mild conditions, which showed their potential applications in wastewater treatment. - Graphical abstract: Schematic of the four-step process of the photon-driven CT model for NG–ZnS QDs. - Highlights: • A new strategy was present to synthesize nitrogen-doped graphene–ZnS quantum dots (NG–ZnS QDs) composites. • [(Zn{sub 2}S{sub 2}) (pa)] nanosheets were used not only as the sources of ZnS QDs but also as the sources of nitrogen. • The photocatalytic activities of NG–ZnS QDs could be remarkably enhanced.
Biomass derived nitrogen-doped hierarchical porous carbon sheets for supercapacitors with high performance.

Science.gov (United States)

Wang, Cunjing; Wu, Dapeng; Wang, Hongju; Gao, Zhiyong; Xu, Fang; Jiang, Kai

2018-08-01

A facile potassium chloride salt-locking technique combined with hydrothermal treatment on precursors was explored to prepare nitrogen-doped hierarchical porous carbon sheets in air from biomass. Benefiting from the effective synthesis strategy, the as-obtained carbon possesses a unique nitrogen-doped thin carbon sheet structure with abundant hierarchical pores and large specific surface areas of 1459 m 2  g -1 . The doped nitrogen in carbon framework has a positive effect on the electrochemical properties of the electrode material, the thin carbon sheet structure benefits for fast ion transfer, the abundant meso-pores provide convenient channels for rapid charge transportation, large specific surface area and lots of micro-pores guarantee sufficient ion-storage sites. Therefore, applied for supercapacitors, the carbon electrode material exhibits an outstanding specific capacitance of 451 F g -1 at 0.5 A g -1 in a three-electrode system. Moreover, the assembled symmetric supercapacitor based on two identical carbon electrodes also displays high specific capacitance of 309 F g -1 at 0.5 A g -1 , excellent rate capacity and remarkable cycling stability with 99.3% of the initial capacitance retention after 10,000 cycles at 5 A -1 . The synthesis strategy avoids expensive inert gas protection and the use of corrosive KOH and toxic ZnCl 2 activated reagents, representing a promising green route to design advanced carbon electrode materials from biomass for high-capacity supercapacitors. Copyright © 2018. Published by Elsevier Inc.
Energetic Metastable Oxygen and Nitrogen Atoms in the Terrestrial Atmosphere

Science.gov (United States)

Kharchenko, Vasili; Dalgarno, A.

2005-01-01

This report summarizes our research performed under NASA Grant NAG5-11857. The three-year grant have been supported by the Geospace Sciences SR&T program. We have investigated the energetic metastable oxygen and nitrogen atoms in the terrestrial stratosphere, mesosphere and thermosphere. Hot atoms in the atmosphere are produced by solar radiation, the solar wind and various ionic reactions. Nascent hot atoms arise in ground and excited electronic states, and their translational energies are larger by two - three orders of magnitude than the thermal energies of the ambient gas. The relaxation kinetics of hot atoms determines the rate of atmospheric heating, the intensities of aeronomic reactions, and the rate of atom escape from the planet. Modeling of the non-Maxwellian energy distributions of metastable oxygen and nitrogen atoms have been focused on the determination of their impact on the energetics and chemistry of the terrestrial atmosphere between 25 and 250 km . At this altitudes, we have calculated the energy distribution functions of metastable O and N atoms and computed non-equilibrium rates of important aeronomic reactions, such as destruction of the water molecules by O(1D) atoms and production of highly excited nitric oxide molecules. In the upper atmosphere, the metastable O(lD) and N(2D) play important role in formation of the upward atomic fluxes. We have computed the upward fluxes of the metastable and ground state oxygen atoms in the upper atmosphere above 250 km. The accurate distributions of the metastable atoms have been evaluated for the day and night-time conditions.
First-principles study of nitrogen doping in cubic and amorphous Ge{sub 2}Sb{sub 2}Te{sub 5}

Energy Technology Data Exchange (ETDEWEB)

Caravati, S; Mazzarello, R; Kuehne, T D; Parrinello, M [Computational Science, Department of Chemistry and Applied Biosciences, ETH Zurich, USI Campus, Via Giuseppe Buffi 13, CH-6900 Lugano (Switzerland); Colleoni, D; Bernasconi, M [Dipartimento di Scienza dei Materiali, Universita di Milano-Bicocca, Via R Cozzi 53, I-20125 Milano (Italy); Krack, M [Paul Scherrer Institut, CH-5232 Villigen (Switzerland)

2011-07-06

We investigated the structural, electronic and vibrational properties of amorphous and cubic Ge{sub 2}Sb{sub 2}Te{sub 5} doped with N at 4.2 at.% by means of large scale ab initio simulations. Nitrogen can be incorporated in molecular form in both the crystalline and amorphous phases at a moderate energy cost. In contrast, insertion of N in the atomic form is very energetically costly in the crystalline phase, though it is still possible in the amorphous phase. These results support the suggestion that N segregates at the grain boundaries during the crystallization of the amorphous phase, resulting in a reduction in size of the crystalline grains and an increased crystallization temperature.
Effect of sputtering power on structure, adhesion strength and corrosion resistance of nitrogen doped diamond-like carbon thin films.

Science.gov (United States)

Khun, N W; Liu, E

2011-06-01

Nitrogen doped diamond-like carbon (DLC:N) thin films were deposited on highly conductive p-Si substrates using a DC magnetron sputtering deposition system. The DLC:N films were characterized using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM), contact angle measurement and micro-scratch test. The XPS and Raman results indicated that the sputtering power significantly influenced the properties of the films in terms of bonding configuration in the films. The corrosion performance of the DLC:N films was investigated in a 0.6 M NaCl solution by means of potentiodynamic polarization testing. It was found that the corrosion performance of the films could be enhanced by higher sputtering powers.
Nitrogen-tuned bonding mechanism of Li and Ti adatom embedded graphene

International Nuclear Information System (INIS)

Lee, Sangho; Chung, Yong-Chae

2013-01-01

The effects of nitrogen defects on the bonding mechanism and resultant binding energy between the metal and graphene layer were investigated using density functional theory (DFT) calculations. For the graphitic N-doped graphene, Li adatom exhibited ionic bonding character, while Ti adatom showed features of covalent bonding similar to that of pristine graphene. However, in the cases of pyridinic and pyrrolic structures, partially covalent bonding characteristic occurred around N atoms in the process of binding with metals, and this particular bond formation enhanced the bond strength of metal on the graphene layer as much as it exceeded the cohesive energy of the metal bulk. Thus, Li and Ti metals are expected to be dispersed with atomic accuracy on the pyridinic and pyrrolic N-doped graphene layers. These results demonstrate that the bonding mechanism of metal–graphene complex can change according to the type of N defect, and this also affects the binding results. - Graphical abstract: Display Omitted - Highlights: • Nitrogen defects changed the bonding mechanism between metal and graphene. • Bonding character and binding results were investigated using DFT calculations. • Covalent bonding character occurred around pyridinic and pyrrolic N-doped graphene. • Pyridinic and pyrrolic N atoms are effective for metal dispersion on the graphene
Room temperature ferromagnetism and absorption red-shift in nitrogen-doped TiO{sub 2} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Gómez-Polo, C., E-mail: gpolo@unavarra.es [Departamento de Física, Universidad Pública de Navarra, Campus de Arrosadia, 31006 Pamplona (Spain); Larumbe, S. [Departamento de Física, Universidad Pública de Navarra, Campus de Arrosadia, 31006 Pamplona (Spain); Monge, M. [Departamento de Química, Universidad de la Rioja, Centro de Investigación en Síntesis Química (CISQ), Complejo Científico Tecnológico, 26006 Logroño (Spain)

2014-11-05

Highlights: • N-doped TiO{sub 2} anatase nanoparticles were obtained by sol–gel. • The nanoparticle size, controlled by the N doping, determines lattice parameters. • Correlation between room temperature ferromagnetism and absorption red-shift. • Oxygen vacancies reinforce both phenomena. • Metal transition impurities contribute to the room temperature ferromagnetism. - Abstract: In this work, room-temperature ferromagnetism and the red-shift of the optical absorption is analyzed in nitrogen doped TiO{sub 2} semiconductor nanoparticles. The nanoparticles were synthesized by the sol–gel method using urea as the nitrogen source. Titanium Tetraisopropoxide (TTIP) was employed as the alkoxyde precursor and dissolved in ethanol. The as prepared gels were dried and calcined in air at 300 °C. Additionally, post-annealing treatments under vacuum atmosphere were performed to modify the oxygen stoichiometry of the samples. The anatase lattice parameters, analyzed by means of powder X-ray diffractometry, depend on the nanometer grain size of the nanoparticles (increase and decrease, respectively, of the tetragonal a and c lattice parameters with respect to the bulk values). The diffuse reflectance ultraviolet–visible (UV–Vis) absorbance spectra show a clear red-shift as consequence of the nitrogen and the occurrence of intragap energy levels. The samples display ferromagnetic features at room temperature that are reinforced with the nitrogen content and after the post annealings in vacuum. The results indicate a clear correlation between the room temperature ferromagnetism and the shift of the absorbance spectrum. In both phenomena, oxygen vacancies (either induced by the nitrogen doping or by the post vacuum annealings) play a dominant role. However, we conclude the existence of very low concentration of diluted transition metal impurities that determine the room ferromagnetic response (bound magnetic polaron BMP model). The contraction of the c soft axis

First-principle study of single TM atoms X (X=Fe, Ru or Os) doped monolayer WS2 systems

Science.gov (United States)

Zhu, Yuan-Yan; Zhang, Jian-Min

2018-05-01

We report the structural, magnetic and electronic properties of the pristine and single TM atoms X (X = Fe, Ru or Os) doped monolayer WS2 systems based on first-principle calculations. The results show that the W-S bond shows a stronger covalent bond, but the covalency is obviously weakened after the substitution of W atom with single X atoms, especially for Ru (4d75s1) with the easily lost electronic configuration. The smaller total energies of the doped systems reveal that the spin-polarized states are energetically favorable than the non-spin-polarized states, and the smallest total energy of -373.918 eV shows the spin-polarized state of the Os doped monolayer WS2 system is most stable among three doped systems. In addition, although the pristine monolayer WS2 system is a nonmagnetic-semiconductor with a direct band gap of 1.813 eV, single TM atoms Fe and Ru doped monolayer WS2 systems transfer to magnetic-HM with the total moments Mtot of 1.993 and 1.962 μB , while single TM atom Os doped monolayer WS2 systems changes to magnetic-metal with the total moments Mtot of 1.569 μB . Moreover, the impurity states with a positive spin splitting energies of 0.543, 0.276 and 0.1999 eV near the Fermi level EF are mainly contributed by X-dxy and X-dx2-y2 states hybridized with its nearest-neighbor atom W-dz2 states for Fe, Ru and Os doped monolayer WS2 system, respectively. Finally, we hope that the present study on monolayer WS2 will provide a useful theoretical guideline for exploring low-dimensional spintronic materials in future experiments.
Facile preparation of nitrogen-doped porous carbon from waste tobacco by a simple pre-treatment process and their application in electrochemical capacitor and CO{sub 2} capture

Energy Technology Data Exchange (ETDEWEB)

Sha, Yunfei; Lou, Jiaying [Technical Center, Shanghai Tobacco Group Co., Ltd., Shanghai 200082 (China); Bai, Shizhe [Department of Chemistry, Fudan University, Shanghai 200433 (China); Wu, Da, E-mail: wud@sh.tobacco.com.cn [Technical Center, Shanghai Tobacco Group Co., Ltd., Shanghai 200082 (China); Liu, Baizhan [Technical Center, Shanghai Tobacco Group Co., Ltd., Shanghai 200082 (China); Ling, Yun, E-mail: yunling@fudan.edu.cn [Department of Chemistry, Fudan University, Shanghai 200433 (China)

2015-04-15

Highlights: • A pre-treatment process is used to prepared N-doped carbon from waste biomass. • Waste tobaccos, which are limited for the disposal, are used as the raw materials. • The product shows a specific surface area and nitrogen content. • Its electrochemical performance is better than commercial activated carbon. • Its CO{sub 2} sorption performance is also better than commercial activated carbon. - Abstract: Preparing nitrogen-doped porous carbons directly from waste biomass has received considerable interest for the purpose of realizing the atomic economy. In this study, N-doped porous carbons have been successfully prepared from waste tobaccos (WT) by a simple pre-treatment process. The sample calcinated at 700 °C (WT-700) shows a micro/meso-porous structures with a BET surface area of 1104 m{sup 2} g{sup −1} and a nitrogen content of ca. 19.08 wt.% (EDS). Performance studies demonstrate that WT-700 displays 170 F g{sup −1} electrocapacitivity at a current density of 0.5 A g{sup −1} (in 6 M KOH), and a CO{sub 2} capacity of 3.6 mmol g{sup −1} at 0 °C and 1 bar, and a selectivity of ca. 32 for CO{sub 2} over N{sub 2} at 25 °C. Our studies indicate that it is feasible to prepare N-enriched porous carbons from waste natural crops by a pre-treatment process for potential industrial application.
Nitrogen-doped graphene by ball-milling graphite with melamine for energy conversion and storage

International Nuclear Information System (INIS)

Xue, Yuhua; Chen, Hao; Qu, Jia; Dai, Liming

2015-01-01

N-doped graphene was prepared by ball milling of graphite with melamine. It was found that ball-milling reduced the size of graphite particles from 30 to 1 μm and facilitated the exfoliation of the resultant small particles into few-layer N-doped graphene nanosheets under ultrasonication. The as-prepared N-doped graphene nanoplatelets (NGnPs) exhibited a nitrogen content as high as 11.4 at.%, making them attractive as efficient electrode materials in supercapacitors for energy storage and as highly-active metal-free catalysts for oxygen reduction in fuel cells for energy conversion. (paper)
Enhanced Doping Efficiency of Al-Doped ZnO by Atomic Layer Deposition Using Dimethylaluminum Isopropoxide as an Alternative Aluminum Precursor

NARCIS (Netherlands)

Wu, Y.; Potts, S.E.; Hermkens, P.M.; Knoops, H.C.M.; Roozeboom, F.; Kessels, W.M.M.

2013-01-01

Atomic layer deposition offers the unique opportunity to control, at the atomic level, the 3D distribution of dopants in highly uniform and conformal thin films. Here, it is demonstrated that the maximum doping efficiency of Al in ZnO can be improved from ∼10% to almost 60% using dimethylaluminum
Effect of nitrogen doping on the microstructure and visible light photocatalysis of titanate nanotubes by a facile cohydrothermal synthesis via urea treatment

International Nuclear Information System (INIS)

Hu, Cheng-Ching; Hsu, Tzu-Chien; Lu, Shan-Yu

2013-01-01

A facile one-step cohydrothermal synthesis via urea treatment has been adopted to prepare a series of nitrogen-doped titanate nanotubes with highly efficient visible light photocatalysis of rhodamine B, in an effect to identify the effect of nitrogen doping on the photodegradation efficiency. The morphology and microstructure of the thus-prepared N-doped titanates were characterized by nitrogen adsorption/desorption isotherms, transmission electron microscopy, and scanning electron microscopy. With increasing urea loadings, the N-doped titanates change from a porous multi-layer and nanotube-shaped to a dense and aggregated particle-shaped structure, accompanied with reduced specific surface area and pore volume and enhanced pore diameter. Interstitial linkage to titanate via Ti-O-N and Ti-N-O is confirmed by X-ray photoelectron spectroscopy. Factors governing the photocatalytic degradation such as the specific surface area of the catalyst and the degradation pathway are analyzed, a mechanistic illustration on the photodegradation is provided, and a 3-stage degradation mechanism is identified. The synergistic contribution due to the enhanced deethylation and chromophore cleavage on rhodamine B molecules and the reduced band gap on the catalyst TiO 2 by interstitial nitrogen-doping has been accounted for the high photodegradation efficiency of the N-doped titanate nanotubes.
The relation between the production efficiency of nitrogen atoms and the electrical characteristics of a dielectric barrier discharge

NARCIS (Netherlands)

Peeters, F.J.J.; Yang, R.; van de Sanden, M.C.M.

2015-01-01

In a nitrogen plasma jet, atomic nitrogen is the longest lived radical species and, through recombination, gives rise to highly reactive excited nitrogen species. In this paper, the atomic nitrogen concentration in the effluent of a nitrogen-fed dielectric barrier discharge (DBD) is determined by
Effect of nitrogen doping on the structural, optical and electrical properties of indium tin oxide films prepared by magnetron sputtering for gallium nitride light emitting diodes

Science.gov (United States)

Tian, Lifei; Cheng, Guoan; Wang, Hougong; Wu, Yulong; Zheng, Ruiting; Ding, Peijun

2017-01-01

The indium tin oxide (ITO) films are prepared by the direct current magnetron sputtering technology with an ITO target in a mixture of argon and nitrogen gas at room temperature. The blue transmittance at 455 nm rises from 63% to 83% after nitrogen doping. The resistivity of the ITO film reduces from 4.6 × 10-3 (undoped film) to 5.7 × 10-4 Ω cm (N-doped film). The X-ray photoelectron spectroscopy data imply that the binding energy of the In3d5/2 peak is declined 0.05 eV after nitrogen doping. The high resolution transmission electron microscope images show that the nitrogen loss density of the GaN/ITO interface with N-doped ITO film is smaller than that of the GaN/ITO interface with undoped ITO film. The forward turn-on voltage of gallium nitride light emitting diode reduces by 0.5 V after nitrogen doping. The fabrication of the N-doped ITO film is conducive to modify the N component of the interface between GaN and ITO layer.
First-principles investigation of adsorption and diffusion of Li on doped silicenes: Prospective materials for lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Momeni, Mohammad Jafar; Mousavi-Khoshdel, Morteza, E-mail: mmousavi@iust.ac.ir; Targholi, Ehsan

2017-05-01

In this report, we investigate the adsorption energies and diffusion characteristics of Li atom on doped silicenes using first principles density functional theory (DFT) calculations. Our results show that the Li adsorption energy on doped silicenes is larger than pristine silicene. Based on our calculations, Al- and B-doped silicenes, due to creating an electron-deficient center in silicene, show a stronger interaction with Li atom compared to P- and N-doped silicenes. The obtained data for surface and perpendicular diffusion of Li atom show the easier mobility of Li on some doped silicenes compared to pristine silicene. According to our results, doping silicene with nitrogen and phosphorus atoms facilitates the Li surface mobility (diffusion barrier of 0.05 and 0.11 eV, respectively versus 0.18 eV for pure silicene) while, doping with aluminum, speed Li perpendicular diffusion (1.47 eV versus 1.67 eV for pristine silicene). The adsorption energy and diffusion barrier values, show the advantage of doped silicenes for use in LIBs with respect to pure silicene. - Highlights: • Calculation of adsorption energy of lithium on pristine and doped silicenes. • Surface and perpendicular diffusion barrier of Li on doped silicenes. • Examination of electronic structure of Li adsorbed doped silicenes.
First-principles investigation of adsorption and diffusion of Li on doped silicenes: Prospective materials for lithium-ion batteries

International Nuclear Information System (INIS)

Momeni, Mohammad Jafar; Mousavi-Khoshdel, Morteza; Targholi, Ehsan

2017-01-01

In this report, we investigate the adsorption energies and diffusion characteristics of Li atom on doped silicenes using first principles density functional theory (DFT) calculations. Our results show that the Li adsorption energy on doped silicenes is larger than pristine silicene. Based on our calculations, Al- and B-doped silicenes, due to creating an electron-deficient center in silicene, show a stronger interaction with Li atom compared to P- and N-doped silicenes. The obtained data for surface and perpendicular diffusion of Li atom show the easier mobility of Li on some doped silicenes compared to pristine silicene. According to our results, doping silicene with nitrogen and phosphorus atoms facilitates the Li surface mobility (diffusion barrier of 0.05 and 0.11 eV, respectively versus 0.18 eV for pure silicene) while, doping with aluminum, speed Li perpendicular diffusion (1.47 eV versus 1.67 eV for pristine silicene). The adsorption energy and diffusion barrier values, show the advantage of doped silicenes for use in LIBs with respect to pure silicene. - Highlights: • Calculation of adsorption energy of lithium on pristine and doped silicenes. • Surface and perpendicular diffusion barrier of Li on doped silicenes. • Examination of electronic structure of Li adsorbed doped silicenes.
Nitrogen-doped carbon nanotubes as a metal catalyst support

CSIR Research Space (South Africa)

Mabena, LF

2011-05-01

Full Text Available ., which are among the most commonly used heterogeneous catalyst supports (Mart??nez-Me?ndez et al. 2006). Catalyst activity depends on the particle size and appropriate dis- tance between each particle. These catalysts deposited on a support... supported Pt electrodes. Appl Catal B Environ 80:286?295 Maldonado S, Morin S, Stevenson KJ (2006) Structure, composition, and chemical reactivity of carbon nanotubes by selective nitrogen doping. Carbon 44:1429?1437 Mart??nez-Me?ndez S, Henr??quez Y...
Facile fabrication of palladium-ionic liquids-nitrogen-doped graphene nanocomposites as enhanced electro-catalyst for ethanol oxidation

Science.gov (United States)

Li, Shuwen; Yang, Honglei; Ren, Ren; Ma, Jianxin; Jin, Jun; Ma, Jiantai

2015-10-01

The palladium-ionic liquids-nitrogen-doped graphene nanocomposites are facile fabricated as enhanced electro-catalyst for ethanol oxidation. First, the ionic liquids functionalized nitrogen-doping graphene nanosheets (PDIL-NGS) with few layers is synthesized through a facile and effective one-pot hydrothermal method with graphene oxide as raw material, urea as reducing-doping agents and ionic liquids (ILs) derived from 3,4,9,10-perylene tetracarboxylic acid as functional molecules. The results of systematic characterization reveal that the PDIL molecules not only can functionalize NGS by π-π stacking with no affecting the nitrogen doping but also prevent the agglomeration of NGS. More importantly, the processing performance and the property of electron transfer are remarkably enhanced duo to introducing a large number of ILs groups. Then, the enhanced electrocatalytic Pd nanoparticles are successfully anchored on PDIL-NGS by a facile and surfactant-free synthetic technique. As an anode catalyst, the novel catalyst exhibits better kinetics, more superior electrocatalytic performance, higher tolerance and electrochemical stability than the other catalysts toward ethanol electrooxidation, owing to the role of PDIL molecules. Therefore, the new catalyst is believed to have the potential use for direct alcohol fuel cells in the future and the functionalized NGS is promising useful materials applied in other fields.
Photoluminescence of phosphorus atomic layer doped Ge grown on Si

Science.gov (United States)

Yamamoto, Yuji; Nien, Li-Wei; Capellini, Giovanni; Virgilio, Michele; Costina, Ioan; Schubert, Markus Andreas; Seifert, Winfried; Srinivasan, Ashwyn; Loo, Roger; Scappucci, Giordano; Sabbagh, Diego; Hesse, Anne; Murota, Junichi; Schroeder, Thomas; Tillack, Bernd

2017-10-01

Improvement of the photoluminescence (PL) of Phosphorus (P) doped Ge by P atomic layer doping (ALD) is investigated. Fifty P delta layers of 8 × 1013 cm-2 separated by 4 nm Ge spacer are selectively deposited at 300 °C on a 700 nm thick P-doped Ge buffer layer of 1.4 × 1019 cm-3 on SiO2 structured Si (100) substrate. A high P concentration region of 1.6 × 1020 cm-3 with abrupt P delta profiles is formed by the P-ALD process. Compared to the P-doped Ge buffer layer, a reduced PL intensity is observed, which might be caused by a higher density of point defects in the P delta doped Ge layer. The peak position is shifted by ˜0.1 eV towards lower energy, indicating an increased active carrier concentration in the P-delta doped Ge layer. By introducing annealing at 400 °C to 500 °C after each Ge spacer deposition, P desorption and diffusion is observed resulting in relatively uniform P profiles of ˜2 × 1019 cm-3. Increased PL intensity and red shift of the PL peak are observed due to improved crystallinity and higher active P concentration.
Nitrogen Doped Graphene Supported Pt Nanoflowers as Electrocatalysts for Oxidation of Formaldehyde.

Science.gov (United States)

Xie, Aijuan; Zhou, Wenting; Luo, Shiping; Chen, Yu; Zhou, Xiaoqing; Chao, Yao

2017-02-01

A facile Pt nanoflowers/nitrogen-doped graphene (PtNFs/NG) electrocatalyst was prepared via depositing Pt nanoflowers (PtNFs) onto the nitrogen-doped graphene (NG) matrix with urea as the nitrogen source and PtNFs/NG modified glassy carbon electrode (GCE) was prepared by electro-chemical method. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscope, X-ray photoelectron spectroscopy (XPS) and Scanning electron microscope (SEM) were used to characterize the resulting composites. Also oxidation of formaldehyde on the resulting PtNFs/NG modified electrode was investigated. The influence of deposition time, electrodeposition potential and formaldehyde concentration on electrooxidation of formaldehyde was detected, the experimental results indicate the high performance of PtNFs/NG catalyst for formaldehyde oxidation is at electrodeposition time of 300 s with the applied potential of −0.3 V. Electrochemical process, electrocatalytic stability and chronoamperometry were also inspected, it was indicated that formalde-hyde oxidation reaction on the PtNFs/NG electrode is diffusion-controlled and PtNFs/NG exhibits a high catalytic activity, stability as well as excellent poisoning-tolerance towards formaldehyde oxidation, which is attributed to the synergistic effect of PtNFs and NG. It turns out that PtNFs/NG can be used in direct liquid-feed fuel cells as a promising alternative catalyst.
Atomic layer deposition of B-doped ZnO using triisopropyl borate as the boron precursor and comparison with Al-doped ZnO

NARCIS (Netherlands)

Garcia - Alonso, D.; Potts, S.E.; Helvoirt, van C.A.A.; Verheijen, M.A.; Kessels, W.M.M.

2015-01-01

Doped ZnO films are an important class of transparent conductive oxides, with many applications demanding increased growth control and low deposition temperatures. Therefore, the preparation of B-doped ZnO films by atomic layer deposition (ALD) at 150 °C was studied. The B source was triisopropyl
Facile Synthesis of ZnO Nanoparticles on Nitrogen-Doped Carbon Nanotubes as High-Performance Anode Material for Lithium-Ion Batteries

Directory of Open Access Journals (Sweden)

Haipeng Li

2017-09-01

Full Text Available ZnO/nitrogen-doped carbon nanotube (ZnO/NCNT composite, prepared though a simple one-step sol-gel synthetic technique, has been explored for the first time as an anode material. The as-prepared ZnO/NCNT nanocomposite preserves a good dispersity and homogeneity of the ZnO nanoparticles (~6 nm which deposited on the surface of NCNT. Transmission electron microscopy (TEM reveals the formation of ZnO nanoparticles with an average size of 6 nm homogeneously deposited on the surface of NCNT. ZnO/NCNT composite, when evaluated as an anode for lithium-ion batteries (LIBs, exhibits remarkably enhanced cycling ability and rate capability compared with the ZnO/CNT counterpart. A relatively large reversible capacity of 1013 mAh·g−1 is manifested at the second cycle and a capacity of 664 mAh·g−1 is retained after 100 cycles. Furthermore, the ZnO/NCNT system displays a reversible capacity of 308 mAh·g−1 even at a high current density of 1600 mA·g−1. These electrochemical performance enhancements are ascribed to the reinforced accumulative effects of the well-dispersed ZnO nanoparticles and doping nitrogen atoms, which can not only suppress the volumetric expansion of ZnO nanoparticles during the cycling performance but also provide a highly conductive NCNT network for ZnO anode.
Synthesis of boron and nitrogen co-doped carbon nanofiber as efficient metal-free electrocatalyst for the VO"2"+/VO_2"+ Redox Reaction

International Nuclear Information System (INIS)

Shi, Lang; Liu, Suqin; He, Zhen; Yuan, Hao; Shen, Junxi

2015-01-01

Boron or nitrogen mono-doped carbon nanofiber (CNF), and boron, nitrogen co-doped CNF are intentionally prepared as positive electrodes in a vanadium redox flow battery (VRFB). The structures and electrochemical properties of the materials are investigated by Scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, cyclic voltammetry and electrochemical impendence spectroscopy. The experimental results indicate that either B or N mono-doped CNF shown better electrochemical performance than untreated one. Interestingly, for the B and N co-doped CNF, the separated case exhibited an outstanding electrochemical activity better than either B or N mono-doped case, while the bonded case leading to a sharp drop in conductivity and shown poor electrochemical performances. These results demonstrated that not the total amount of incorporated B and N but how the B and N are incorporated into carbon nanostructures determines the catalytic activity toward VO"2"+/VO_2"+ reaction. Moreover, the individual mechanism of the nitrogen and boron containing functional groups act as active sites have been analyzed.
Characterization of N-doped multilayer graphene grown on 4H-SiC (0001)

International Nuclear Information System (INIS)

Arezki, Hakim; Jaffré, Alexandre; Alamarguy, David; Alvarez, José; Kleider, Jean-Paul; Boutchich, Mohamed; Ho, Kuan-I; Lai, Chao-Sung

2015-01-01

Large-area graphene film doped with hetero-atoms is of great interest for a wide spectrum of nanoelectronics applications, such as field effect devices, super capacitors, fuel cells among many others. Here, we report the structural and electronic properties of nitrogen doped multilayer graphene on 4H-SiC (0001). The incorporation of nitrogen during the growth causes an increase in the D band on the Raman signature indicating that the nitrogen is creating defects. The analysis of micro-Raman mapping of G, D, 2D bands shows a predominantly trilayer graphene with a D band inherent to doping and inhomogeneous dopant distribution at the step edges. Ultraviolet photoelectron spectroscopy (UPS) indicates an n type work function (WF) of 4.1 eV. In addition, a top gate FET device was fabricated showing n-type I-V characteristic after the desorption of oxygen with high electron and holes mobilities
A first-principles study of group IV and VI atoms doped blue phosphorene

Science.gov (United States)

Bai, Ruimin; Chen, Zheng; Gou, Manman; Zhang, Yixin

2018-02-01

Using first-principles calculations, we have systematically investigated the structural, electronic and magnetic properties of blue phosphorene doped by group IV and VI atoms, including C, Si, Ge, Sn, O, S, Se and Te. All the doped systems are energetically stable. Only C, Si, Ge and O-substituted systems show the characteristics of spin polarization and the magnetic moments are all 1.0 μB. Moreover, we found that C, Si, Ge and O doped systems are indirect bandgap semiconductors, while Sn, S, Se and Te doped systems present metallic property. These results show that blue phosphorene can be used prospectively in optoelectronic and spintronic devices.
Low-Temperature Sol-Gel Synthesis of Nitrogen-Doped Anatase/Brookite Biphasic Nanoparticles with High Surface Area and Visible-Light Performance

Directory of Open Access Journals (Sweden)

Liang Jiang

2017-12-01

Full Text Available Nitrogen doping in combination with the brookite phase or a mixture of TiO2 polymorphs nanomaterials can enhance photocatalytic activity under visible light. Generally, nitrogen-dopedanatase/brookite mixed phases TiO2 nanoparticles obtained by hydrothermal or solvothermal method need to be at high temperature and with long time heating treatment. Furthermore, the surface areas of them are low (<125 m2/g. There is hardly a report on the simple and direct preparation of N-doped anatase/brookite mixed phase TiO2 nanostructures using sol-gel method at low heating temperature. In this paper, the nitrogen-doped anatase/brookite biphasic nanoparticles with large surface area (240 m2/g were successfully prepared using sol-gel method at low temperature (165 °C, and with short heating time (4 h under autogenous pressure. The obtained sample without subsequent annealing at elevated temperatures showed enhanced photocatalytic efficiency for the degradation of methyl orange (MO with 4.2-, 9.6-, and 7.5-fold visible light activities compared to P25 and the amorphous samples heated in muffle furnace with air or in tube furnace with a flow of nitrogen at 165 °C, respectively. This result was attributed to the synergistic effects of nitrogen doping, mixed crystalline phases, and high surface area.
Rectification induced in N2AA-doped armchair graphene nanoribbon device

International Nuclear Information System (INIS)

Chen, Tong; Wang, Ling-Ling; Luo, Kai-Wu; Xu, Liang; Li, Xiao-Fei

2014-01-01

By using non-equilibrium Green function formalism in combination with density functional theory, we investigated the electronic transport properties of armchair graphene nanoribbon devices in which one lead is undoped and the other is N 2 AA -doped with two quasi-adjacent substitutional nitrogen atoms incorporating pairs of neighboring carbon atoms in the same sublattice A. Two kinds of N 2 AA -doped style are considered, for N dopants substitute the center or the edge carbon atoms. Our results show that the rectification behavior with a large rectifying ratio can be found in these devices and the rectifying characteristics can be modulated by changing the width of graphene nanoribbons or the position of the N 2 AA dopant. The mechanisms are revealed to explain the rectifying behaviors.

Improved Electrochemical Performance of Biomass-Derived Nanoporous Carbon/Sulfur Composites Cathode for Lithium-Sulfur Batteries by Nitrogen Doping

International Nuclear Information System (INIS)

Geng, Zhen; Xiao, Qiangfeng; Wang, Dabin; Yi, Guanghai; Xu, Zhigang; Li, Bing; Zhang, Cunman

2016-01-01

A two-step method with high-efficiency is developed to prepare nitrogen doped activated carbons (NACs) with high surface area and nitrogen content. Based on the method, series of NACs with similar surface area and pore texture but different nitrogen content and nitrogen group species are successfully prepared. The influence of nitrogen doping on electrochemical performance of carbon/sulfur composites cathode is studied deeply under the conditions of similar surface area and pore texture. It presents the directly experimental demonstration that both nitrogen content and nitrogen group species play crucial roles on electrochemical performance of carbon/sulfur composites cathode. NAC/sulfur composites show the much improved cycling performance, which is about 3.5 times as that of nitrogen free carbon. Improved electrochemical performance is due to synergistic effects between nitrogen content and effective nitrogen groups, which enables effective trapping of lithium polysulfides within carbon framework. Besides, it is found that oxygen groups exist in carbon materials obviously influence electrochemical performance of cathode, which could be ignored in most of studies. Based on above, it can be concluded that enhanced chemisorption to lithium polysulfides by functional groups modification is the effective route to improve the electrochemical performance of Li-S battery.
Strategy for designing stable and powerful nitrogen-rich high-energy materials by introducing boron atoms.

Science.gov (United States)

Wu, Wen-Jie; Chi, Wei-Jie; Li, Quan-Song; Li, Ze-Sheng

2017-06-01

One of the most important aims in the development of high-energy materials is to improve their stability and thus ensure that they are safe to manufacture and transport. In this work, we theoretically investigated open-chain N 4 B 2 isomers using density functional theory in order to find the best way of stabilizing nitrogen-rich molecules. The results show that the boron atoms in these isomers are aligned linearly with their neighboring atoms, which facilitates close packing in the crystals of these materials. Upon comparing the energies of nine N 4 B 2 isomers, we found that the structure with alternating N and B atoms had the lowest energy. Structures with more than one nitrogen atom between two boron atoms had higher energies. The energy of N 4 B 2 increases by about 50 kcal/mol each time it is rearranged to include an extra nitrogen atom between the two boron atoms. More importantly, our results also show that boron atoms stabilize nitrogen-rich molecules more efficiently than carbon atoms do. Also, the combustion of any isomer of N 4 B 2 releases more heat than the corresponding isomer of N 4 C 2 does under well-oxygenated conditions. Our study suggests that the three most stable N 4 B 2 isomers (BN13, BN24, and BN34) are good candidates for high-energy molecules, and it outlines a new strategy for designing stable boron-containing high-energy materials. Graphical abstract The structural characteristics, thermodynamic stabilities, and exothermic properties of nitrogen-rich N 4 B 2 isomers were investigated by means of density functional theory.
Carbohydrazide-dependent reductant for preparing nitrogen-doped graphene hydrogels as electrode materials in supercapacitor

Energy Technology Data Exchange (ETDEWEB)

Jiang, Man [Resources and Environmental Engineering, Shandong University of Technology, Zibo 255049 (China); Xing, Ling-Bao, E-mail: lbxing@sdut.edu.cn [School of Chemical Engineering, Shandong University of Technology, Zibo 255049 (China); Zhang, Jing-Li; Hou, Shu-Fen; Zhou, Jin; Si, Weijiang; Cui, Hongyou [School of Chemical Engineering, Shandong University of Technology, Zibo 255049 (China); Zhuo, Shuping, E-mail: zhuosp_academic@yahoo.com [School of Chemical Engineering, Shandong University of Technology, Zibo 255049 (China)

2016-04-15

Graphical abstract: - Highlights: • Three-dimensional nitrogen-doped graphene hydrogels (NGHs) were prepared. • Carbohydrazide was used as reducing and doping agents. • NGHs exhibited relatively good electrochemical properties in supercapacitor. • NGHs with different doping of N demonstrated different performances in supercapacitors. - Abstract: Three-dimensional (3D) nitrogen-doped graphene hydrogels (NGHs) are designed and synthesized in an efficient and fast way by using a strong reductant of carbohydrazide as reducing and doping agent in an aqueous solution of graphene oxide (GO). The transformation of GO suspension to the hydrogels can be completed in 1 h, which can be confirmed by X-ray powder diffraction (XRD), Raman spectroscopy, and Fourier transform infrared spectroscopy (FT-IR). With adding different amounts of carbohydrazide, the obtained NGHs behave different doping of N and unlike performances in supercapacitors, which can be demonstrated by elemental analysis and X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), N{sub 2} sorption experiments, and electrochemical measurements, respectively. According to the network architectures, the NGHs all exhibited high specific capacitance, NGHs-1, NGHs-2, NGHs-5 and NGHs-10 showed specific capacitance at 167.7, 156.8, 140.4 and 119.3 F g{sup −1} at 1 A g{sup −1} in KOH electrolyte. The specific capacitance can still be maintained for 80.5, 79.5, 80.3 and 78.6% with an increase of the discharging current density of 10 A g{sup −1}, respectively. More interestingly, the NGHs-1 based supercapacitor also exhibited good electrochemical stability and high degree of reversibility in the long-term cycling test (81.5% retention after 4000 cycles).
Carbohydrazide-dependent reductant for preparing nitrogen-doped graphene hydrogels as electrode materials in supercapacitor

International Nuclear Information System (INIS)

Jiang, Man; Xing, Ling-Bao; Zhang, Jing-Li; Hou, Shu-Fen; Zhou, Jin; Si, Weijiang; Cui, Hongyou; Zhuo, Shuping

2016-01-01

Graphical abstract: - Highlights: • Three-dimensional nitrogen-doped graphene hydrogels (NGHs) were prepared. • Carbohydrazide was used as reducing and doping agents. • NGHs exhibited relatively good electrochemical properties in supercapacitor. • NGHs with different doping of N demonstrated different performances in supercapacitors. - Abstract: Three-dimensional (3D) nitrogen-doped graphene hydrogels (NGHs) are designed and synthesized in an efficient and fast way by using a strong reductant of carbohydrazide as reducing and doping agent in an aqueous solution of graphene oxide (GO). The transformation of GO suspension to the hydrogels can be completed in 1 h, which can be confirmed by X-ray powder diffraction (XRD), Raman spectroscopy, and Fourier transform infrared spectroscopy (FT-IR). With adding different amounts of carbohydrazide, the obtained NGHs behave different doping of N and unlike performances in supercapacitors, which can be demonstrated by elemental analysis and X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), N_2 sorption experiments, and electrochemical measurements, respectively. According to the network architectures, the NGHs all exhibited high specific capacitance, NGHs-1, NGHs-2, NGHs-5 and NGHs-10 showed specific capacitance at 167.7, 156.8, 140.4 and 119.3 F g"−"1 at 1 A g"−"1 in KOH electrolyte. The specific capacitance can still be maintained for 80.5, 79.5, 80.3 and 78.6% with an increase of the discharging current density of 10 A g"−"1, respectively. More interestingly, the NGHs-1 based supercapacitor also exhibited good electrochemical stability and high degree of reversibility in the long-term cycling test (81.5% retention after 4000 cycles).
Mn doped InSb studied at the atomic scale by cross-sectional scanning tunneling microscopy

International Nuclear Information System (INIS)

Mauger, S. J. C.; Bocquel, J.; Koenraad, P. M.; Feeser, C. E.; Parashar, N. D.; Wessels, B. W.

2015-01-01

We present an atomically resolved study of metal-organic vapor epitaxy grown Mn doped InSb. Both topographic and spectroscopic measurements have been performed by cross-sectional scanning tunneling microscopy (STM). The measurements on the Mn doped InSb samples show a perfect crystal structure without any precipitates and reveal that Mn acts as a shallow acceptor. The Mn concentration of the order of ∼10 20 cm −3 obtained from the cross-sectional STM data compare well with the intended doping concentration. While the pair correlation function of the Mn atoms showed that their local distribution is uncorrelated beyond the STM resolution for observing individual dopants, disorder in the Mn ion location giving rise to percolation pathways is clearly noted. The amount of clustering that we see is thus as expected for a fully randomly disordered distribution of the Mn atoms and no enhanced clustering or second phase material was observed
Spin-dependent electronic transport properties of transition metal atoms doped α-armchair graphyne nanoribbons

Science.gov (United States)

Fotoohi, Somayeh; Haji-Nasiri, Saeed

2018-04-01

Spin-dependent electronic transport properties of single 3d transition metal (TM) atoms doped α-armchair graphyne nanoribbons (α-AGyNR) are investigated by non-equilibrium Green's function (NEGF) method combined with density functional theory (DFT). It is found that all of the impurity atoms considered in this study (Fe, Co, Ni) prefer to occupy the sp-hybridized C atom site in α-AGyNR, and the obtained structures remain planar. The results show that highly localized impurity states are appeared around the Fermi level which correspond to the 3d orbitals of TM atoms, as can be derived from the projected density of states (PDOS). Moreover, Fe, Co, and Ni doped α-AGyNRs exhibit magnetic properties due to the strong spin splitting property of the energy levels. Also for each case, the calculated current-voltage characteristic per super-cell shows that the spin degeneracy in the system is obviously broken and the current becomes strongly spin dependent. Furthermore, a high spin-filtering effect around 90% is found under the certain bias voltages in Ni doped α-AGyNR. Additionally, the structure with Ni impurity reveals transfer characteristic that is suitable for designing a spin current switch. Our findings provide a high possibility to design the next generation spin nanodevices with novel functionalities.
Graphene oxide quantum dot-derived nitrogen-enriched hybrid graphene nanosheets by simple photochemical doping for high-performance supercapacitors

Science.gov (United States)

Xu, Yongjie; Li, Xinyu; Hu, Guanghui; Wu, Ting; Luo, Yi; Sun, Lang; Tang, Tao; Wen, Jianfeng; Wang, Heng; Li, Ming

2017-11-01

Nitrogen-enriched graphene was fabricated via a facile strategy. Graphene oxide (GO) nanosheets and graphene oxide quantum dots (GQDs) were used as a structure-directing agent and in situ activating agent, respectively, after photoreduction under NH3 atmosphere. The combination of photoreduction and NH3 not only reduced GO and GQD composites (GO/GQDs) within a shorter duration but also doped a high level of nitrogen on the composites (NrGO/GQDs). The nitrogen content of NrGO/GQDs reached as high as 18.86 at% within 5 min of irradiation. Benefiting from the nitrogen-enriched GO/GQDs hybrid structure, GQDs effectively prevent the agglomeration of GO sheets and increased the numbers of ion channels in the material. Meanwhile, the high levels of nitrogen improved electrical conductivity and strengthened the binding energy between GQD and GO sheets. Compared with reduced GO and low nitrogen-doped reduced GO, NrGO/GQD electrodes exhibited better electrochemical characteristics with a high specific capacitance of 344 F g-1 at a current density of 0.25 A g-1. Moreover, the NrGO/GQD electrodes exhibited 82% capacitance retention after 3000 cycles at a current density of 0.8 A g-1 in 6 M KOH electrolyte. More importantly, the NrGO/GQD electrodes deliver a high energy density of 43 Wh kg-1 at a power density of 417 W kg-1 in 1 M Li2SO4 electrolyte. The nitrogen-doped graphene and corresponding supercapacitor presented in this study are novel materials with potential applications in advanced energy storage systems.
Atmospheric spatial atomic layer deposition of in-doped ZnO

NARCIS (Netherlands)

Illiberi, A.; Scherpenborg, R.; Roozeboom, F.; Poodt, P.

2014-01-01

Indium-doped zinc oxide (ZnO:In) has been grown by spatial atomic layer deposition at atmospheric pressure (spatial-ALD). Trimethyl indium (TMIn), diethyl zinc (DEZ) and deionized water have been used as In, Zn and O precursor, respectively. The metal content of the films is controlled in the range
Synthesis of boron, nitrogen co-doped porous carbon from asphaltene for high-performance supercapacitors

Science.gov (United States)

Zhou, Ying; Wang, Dao-Long; Wang, Chun-Lei; Jin, Xin-Xin; Qiu, Jie-Shan

2014-08-01

Oxidized asphaltene (OA), a thermosetting material with plenty of functional groups, is synthesized from asphaltene (A) using HNO3/H2SO4 as the oxidizing agent. Boron, nitrogen co-doped porous carbon (BNC—OA) is prepared by carbonization of the mixture of boric acid and OA at 1173 K in an argon atmosphere. X-ray photoelectron spectroscopy (XPS) characterization reveals that the BNC—OA has a nitrogen content of 3.26 at.% and a boron content of 1.31 at.%, while its oxidation-free counterpart (BNC—SA) has a nitrogen content of 1.61 at.% and a boron content of 3.02 at.%. The specific surface area and total pore volume of BNC—OA are 1103 m2·g-1 and 0.921 cm3·g-1, respectively. At a current density of 0.1 A·g-1, the specific capacitance of BNC-OA is 335 F·g-1 and the capacitance retention can still reach 83% at 1 A·g-1. The analysis shows that the superior electrochemical performance of the BNC—OA is attributed to the pseudocapacitance behavior of surface heteroatom functional groups and an abundant pore-structure. Boron, nitrogen co-doped porous carbon is a promising electrode material for supercapacitors.
Synthesis of Nitrogen-Doped Mesoporous Carbon for the Catalytic Oxidation of Ethylbenzene

Science.gov (United States)

Wang, Ruicong; Yu, Yifeng; Zhang, Yue; Lv, Haijun; Chen, Aibing

2017-06-01

Nitrogen-doped ordered mesoporous carbon (NOMC) was fabricated via a simple hard-template method by functionalized ionic liquids as carbon and nitrogen source, SBA-15 as a hard-template. The obtained NOMC materials have a high nitrogen content of 5.55 %, a high surface area of 446.2 m2 g-1, and an excellent performance in catalysing oxidation of ethylbenzene. The conversion rate of ethylbenzene can be up to 84.5% and the yield of acetophenone can be up to 69.9%, the results indicated that the NOMC materials have a faster catalytic rate and a higher production of acetophenone than catalyst-free and CMK-3, due to their uniform pore size, high surface area and rich active sites in the carbon pore walls.
Preparation of nitrogen-doped graphene/activated carbon composite papers to enhance energy storage in supercapacitors

Science.gov (United States)

Li, Yong-feng; Liu, Yan-zhen; Liang, Yu; Guo, Xiao-hui; Chen, Cheng-meng

2017-09-01

This report presents a facile and effective method to synthesize freestanding nitrogen-doped reduced graphene oxide (rGO)/activated carbon (AC) composite papers for supercapacitors by a method combining vacuum filtration with post-annealing in NH3 atmosphere. The effect of activated carbon contents on the microstructure and capacitive behavior of the resulting composite papers before and after the annealing was investigated by X-ray diffraction, scanning electron microscopy, and Raman and X-ray photoelectron spectroscopy. Results show that the composite paper with a 30% activated carbon loading has a high nitrogen content of 14.6 at% and superior capacitive performance (308 F/g, 1 A/g) to the other composite papers with various activated carbon loadings. Nitrogen was doped and GO reduced during the annealing. The rGO nanosheets acted as a framework, and the AC particles served as spacers to avoid agglomeration of graphene sheets. The high capacitance of the composite paper is ascribed to the electric double-layer behavior and the reversible redox reactions of the nitrogen and oxygen groups. The entire process is simple, environmental friendly and easily scalable for mass production.
The synergistic effect of nitrogen-doped titanium dioxide/mercaptobenzoic acid/silver nanocomplexes for surface-enhanced Raman scattering

Science.gov (United States)

Feng, Jun; Bao, Wenyuan; Li, Lijun; Cheng, Hao; Huang, Wenyi; Kong, Hongxing; Li, Yanqing

2018-03-01

We synthesized titanium dioxide (TiO2) and nitrogen-doped TiO2 nanoparticles (N-TiO2 NPs) via a sol-hydrothermal method using ammonium chloride (NH4Cl) as the nitrogen (N) source. Furthermore, an N-TiO2/4-mercaptobenzoic acid (4-MBA)/silver (Ag) nanocomplex served as an active substrate for surface-enhanced Raman scattering (SERS) and was prepared by self-assembly. During SERS, the Raman signals of 4-MBA of the N-TiO2/MBA/Ag nanocomplexes exhibited higher intensity and sensitivity than pure TiO2/MBA/Ag, with 1% N doping in N-TiO2, producing the strongest Raman signals. We characterized the N-TiO2 hybrid materials by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and ultraviolet-visible diffuse reflectance spectra. N doping did not influence the phase of the TiO2 crystal. The doped N entered into the crystal lattice of the TiO2, replacing some oxygen (O) to form Ti-O-N or Ti-N-O linkage. The results indicated that an appropriate amount of N doping could enhance the SERS performance of the TiO2 SERS substrate via N substitution doping. These doping forms were beneficial to the molecular charge transfer (CT), and this resulted in improved SERS performance for N-doped TiO2 NPs. We attributed this improvement to the formation of N-doping energy levels that were beneficial to the process of TiO2 to MBA molecule CT. This work not only enriched the nonmetal-doped CT mechanism in SERS but also provided several reference values for practical applications. [Figure not available: see fulltext.
Effective visible light-active nitrogen and samarium co-doped BiVO{sub 4} for the degradation of organic pollutants

Energy Technology Data Exchange (ETDEWEB)

Wang, Min; Niu, Chao [College of Environmental and Chemical Engineering, Shenyang Ligong University, Shenyang 110165 (China); Liu, Jun, E-mail: minwang62@msn.com [Shenyang Military General Hospital, Shenyang 110016 (China); Wang, Qianwu; Yang, Changxiu; Zheng, Haoyan [College of Environmental and Chemical Engineering, Shenyang Ligong University, Shenyang 110165 (China)

2015-11-05

Nitrogen and samarium co-doped BiVO{sub 4} (N–xSm–BiVO{sub 4}) nanoparticles were synthesized using a sol–gel method with a corn stem template. The physicochemical properties of the resultant N–xSm–BiVO{sub 4} particles were characterized using various methods: XPS, XRD, SEM, BET, and UV–Vis DRS analyses. The visible-light photocatalytic activity was successfully demonstrated by degrading a model dye, namely, methyl orange. The dopant content was optimized, and the nitrogen and samarium co-doped BiVO{sub 4} extended the light absorption spectrum toward the visible region, significantly enhancing the photodegradation of the model dye. The Sm and N co-doped BiVO{sub 4} exhibited the highest photocatalytic activity compared to materials with a single dopant or no dopant. The significantly enhanced photocatalytic activity of the N–Sm co-doped BiVO{sub 4} under visible-light irradiation can be attributed to the synergistic effects of the nitrogen and samarium. - Highlights: • The N–Sm codoped BiVO{sub 4} were synthesized using a sol–gel method with a corn stem template. • The N and Sm codoped BiVO{sub 4} has excellent photocatalytic activity of methyl orange degradation. • The maximum activity was observed when the molar ratio of Sm/Bi was 1.0. • The high photocatalytic activity was caused by the synergistic effects between N doping and Sm doping.
Discrete impurity band from surface danging bonds in nitrogen and phosphorus doped SiC nanowires

Science.gov (United States)

Li, Yan-Jing; Li, Shu-Long; Gong, Pei; Li, Ya-Lin; Cao, Mao-Sheng; Fang, Xiao-Yong

2018-04-01

The electronic structure and optical properties of the nitrogen and phosphorus doped silicon carbide nanowires (SiCNWs) are investigated using first-principle calculations based on density functional theory. The results show doping can change the type of the band gap and improve the conductivity. However, the doped SiCNWs form a discrete impurity levels at the Fermi energy, and the dispersion degree decreases with the diameter increasing. In order to reveal the root of this phenomenon, we hydrogenated the doped SiCNWs, found that the surface dangling bonds were saturated, and the discrete impurity levels are degeneracy, which indicates that the discrete impurity band of the doped SiCNWs is derived from the dangling bonds. The surface passivation can degenerate the impurity levels. Therefore, both doping and surface passivation can better improve the photoelectric properties of the SiCNWs. The result can provide additional candidates in producing nano-optoelectronic devices.
Study on the nitrogen-doped W-Sb-Te material for phase change memory application

Energy Technology Data Exchange (ETDEWEB)

Ren, Kun; Xia, Mengjiao; Ding, Keyuan; Ji, Xinglong [State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100080 (China); Rao, Feng, E-mail: fengrao@mail.com.ac.cn; Song, Zhitang; Wu, Liangcai; Liu, Bo; Feng, Songlin [State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

2014-04-28

N doping is proposed to enlarge sensing margin of W{sub 0.08}(Sb{sub 2}Te){sub 0.92} based high-temperature phase-change memories (PCMs). The sensing margin is increased from 30 to 5 × 10{sup 3}, with an increase from 145 °C to 158 °C in data retention. The grain size is reduced to 10 nm. The PCM based on N-W{sub 0.08}(Sb{sub 2}Te){sub 0.92} shows the fast operation speed of 30 ns and good cycling ability of >10{sup 3}. By X-ray photoelectron spectroscopy and ab initio calculation, the W atoms are suggested to locate in the Sb positions and interstices of the lattice. The W atoms in interstice will bond to N atoms during N doping.
A first principle simulation of competitive adsorption of SF6 decomposition components on nitrogen-doped anatase TiO2 (101) surface

Science.gov (United States)

Dong, Xingchen; Zhang, Xiaoxing; Cui, Hao; Zhang, Jun

2017-11-01

Gas insulated switchgear has been widely used in modern electric systems due to its significantly excellent performances such as compact structure and low land occupation as well as the security stability. However, inside defects caused during manufacture process can lead to partial discharge which might develop into serious insulation failure. Online monitoring method on basis of gas sensors is considered a promising way of detecting partial discharge for alarm ahead of time. Research has found that TiO2 nanotubes sensors show good response to SO2, SOF2, SO2F2, the decomposition components as a result of partial discharge. In order to investigate the gas-sensing mechanism of nitrogen-doped TiO2 prepared via plasma treatment methods to SO2, SOF2, and SO2F2, the adsorption structures of both three gas molecules and anatase TiO2 (101) surface were built, and DFT calculations were then carried out for calculation and analysis of adsorption parameters. Adsorption property comparison of anatase TiO2 (101) surface after nitrogen doping with Au doping and without doping shows that nitrogen doping can obviously enhance the adsorption energy for SO2 and SOF2 adsorption and no charge transfer for SO2F2 adsorption, further explaining the adsorption mechanism and doping influence of different doping elements.
Visible light induced electron transfer process over nitrogen doped TiO2 nanocrystals prepared by oxidation of titanium nitride

International Nuclear Information System (INIS)

Wu Zhongbiao; Dong Fan; Zhao Weirong; Guo Sen

2008-01-01

Nitrogen doped TiO 2 nanocrystals with anatase and rutile mixed phases were prepared by incomplete oxidation of titanium nitride at different temperatures. The as-prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), core level X-ray photoelectron spectroscopy (CL XPS), valence band X-ray photoelectron spectroscopy (VB XPS), UV-vis diffuse reflectance spectra (UV-vis DRS), and visible light excited photoluminescence (PL). The photocatalytic activity was evaluated for photocatalytic degradation of toluene in gas phase under visible light irradiation. The visible light absorption and photoactivities of these nitrogen doped TiO 2 nanocrystals can be clearly attributed to the change of the additional electronic (N - ) states above the valence band of TiO 2 modified by N dopant as revealed by the VB XPS and visible light induced PL. A band gap structure model was established to explain the electron transfer process over nitrogen doped TiO 2 nanocrystals under visible light irradiation, which was consistent with the previous theoretical and experimental results. This model can also be applied to understand visible light induced photocatalysis over other nonmetal doped TiO 2
One - Step synthesis of nitrogen doped reduced graphene oxide with NiCo nanoparticles for ethanol oxidation in alkaline media.

Science.gov (United States)

Kakaei, Karim; Marzang, Kamaran

2016-01-15

Development of anode catalysts and catalyst supporting carbonaceous material containing non-precious metal have attracted tremendous attention in the field of direct ethanol fuel cells (DEFCs). Herein, we report the synthesis and electrochemical properties of nitrogen-doped reduced graphene oxide (NRGO) supported Co, Ni and NiCo nanocomposites. The metal NRGO nanocomposites, in which metal nanoparticles are embedded in the highly porous nitrogen-doped graphene matrix, have been synthesized by simply and one-pot method at a mild temperature using GO, urea choline chloride and urea as reducing and doping agent. The fabricated NiCo/NRGO exhibit remarkable electrocatalytic activity (with Tafel slope of 159.1mVdec(-1)) and high stability for the ethanol oxidation reaction (EOR). The superior performance of the alloy based NRGO is attributed to high surface area, well uniform distribution of high-density nitrogen, metal active sites and synergistic effect. Copyright © 2015 Elsevier Inc. All rights reserved.
One step synthesis of chlorine-free Pt/Nitrogen-doped graphene composite for oxygen reduction reaction

KAUST Repository

Varga, Tamá s; Varga, Á gnes Tí mea; Ballai, Gergő; Haspel, Henrik; Kukovecz, Á kos; Kó nya, Z.

2018-01-01

Chlorine-free Platinum/nitrogen-doped graphene oxygen reduction reaction catalysts were synthesized by a one step method of annealing a mixture of platinum acetylacetonate and graphene oxide under ammonia atmosphere. Nanoparticles with close
First-Principles Study on the Structural and Electronic Properties of N Atoms Doped-Rutile TiO2 of Oxygen Vacancies

Directory of Open Access Journals (Sweden)

Zhong-Liang Zeng

2015-01-01

Full Text Available For the propose of considering the actual situation of electronic neutral, a simulation has been down on the basis of choosing the position of dual N and researching the oxygen vacancy. It is found that the reason why crystal material gets smaller is due to the emergence of impurity levels. By introducing the oxygen vacancy to the structure, the results show that while the oxygen vacancy is near the two nitrogen atoms which have a back to back position, its energy gets the lowest level and its structure gets the most stable state. From its energy band structure and density, the author finds that the impurity elements do not affect the migration of Fermi level while the oxygen vacancy has been increased. Instead of that, the conduction band of metal atoms moves to the Fermi level and then forms the N-type semiconductor material, but the photocatalytic activity is not as good as the dual N-doping state.

Energetics of a Li Atom adsorbed on B/N doped graphene with monovacancy

International Nuclear Information System (INIS)

Rani, Babita; Jindal, V.K.; Dharamvir, Keya

2016-01-01

We use density functional theory (DFT) to study the adsorption properties and diffusion of Li atom across B/N-pyridinic graphene. Regardless of the dopant type, B atoms of B-pyridinic graphene lose electron density. On the other hand, N atoms (p-type dopants) have tendency to gain electron density in N-pyridinic graphene. Higher chemical reactivity and electronic conductivity of B/N-pyridinic graphene are responsible for stronger binding of Li with the substrates as compared to pristine graphene. The binding energy of Li with B/N-pyridinic graphene exceeds the cohesive energy of bulk Li, making it energetically unfavourable for Li to form clusters on these substrates. Li atom gets better adsorbed on N-pyridinic graphene due to an additional p-p hybridization of the orbitals while Li on B-pyridinic prefers the ionic bonding. Also, significant distortion of N-pyridinic graphene upon Li adsorption is a consequence of the change in bonding mechanism between Li atom and the substrate. Our results show that bonding character and hence binding energies between Li and graphene can be tuned with the help of B/N doping of monovacancy defects. Further, the sites for most stable adsorption are different for the two types of doped and defective graphene, leading to greater Li uptake capacity of B-pyridinic graphene near the defect. In addition, B-pyridinic graphene offering lower diffusion barrier, ensures better Li kinetics. Thus, B-pyridinic graphene presents itself as a better anode material for LIBs as compared to N-pyridinic graphene. - Graphical abstract: Adsorption and diffusion of Li atom across the B/N doped monovacancy graphene is studied using ab-initio DFT calculations. Our results show that bonding mechanism and binding of Li with graphene can be tuned with the help of N/B doping of defects. Also, B-pyridinic graphene presents itself as a better anode material for lithium ion batteries as compared to N-pyridinic graphene. Display Omitted - Highlights: • Density
Energetics of a Li Atom adsorbed on B/N doped graphene with monovacancy

Energy Technology Data Exchange (ETDEWEB)

Rani, Babita, E-mail: babitabaghla15@gmail.com [Department of Physics, Panjab University, Chandigarh 160014 (India); Department of Physics, Punjabi University, Patiala 147002 (India); Jindal, V.K. [Department of Physics, Panjab University, Chandigarh 160014 (India); Dharamvir, Keya, E-mail: keya@pu.ac.in [Department of Physics, Panjab University, Chandigarh 160014 (India)

2016-08-15

We use density functional theory (DFT) to study the adsorption properties and diffusion of Li atom across B/N-pyridinic graphene. Regardless of the dopant type, B atoms of B-pyridinic graphene lose electron density. On the other hand, N atoms (p-type dopants) have tendency to gain electron density in N-pyridinic graphene. Higher chemical reactivity and electronic conductivity of B/N-pyridinic graphene are responsible for stronger binding of Li with the substrates as compared to pristine graphene. The binding energy of Li with B/N-pyridinic graphene exceeds the cohesive energy of bulk Li, making it energetically unfavourable for Li to form clusters on these substrates. Li atom gets better adsorbed on N-pyridinic graphene due to an additional p-p hybridization of the orbitals while Li on B-pyridinic prefers the ionic bonding. Also, significant distortion of N-pyridinic graphene upon Li adsorption is a consequence of the change in bonding mechanism between Li atom and the substrate. Our results show that bonding character and hence binding energies between Li and graphene can be tuned with the help of B/N doping of monovacancy defects. Further, the sites for most stable adsorption are different for the two types of doped and defective graphene, leading to greater Li uptake capacity of B-pyridinic graphene near the defect. In addition, B-pyridinic graphene offering lower diffusion barrier, ensures better Li kinetics. Thus, B-pyridinic graphene presents itself as a better anode material for LIBs as compared to N-pyridinic graphene. - Graphical abstract: Adsorption and diffusion of Li atom across the B/N doped monovacancy graphene is studied using ab-initio DFT calculations. Our results show that bonding mechanism and binding of Li with graphene can be tuned with the help of N/B doping of defects. Also, B-pyridinic graphene presents itself as a better anode material for lithium ion batteries as compared to N-pyridinic graphene. Display Omitted - Highlights: • Density
Complex boron redistribution kinetics in strongly doped polycrystalline-silicon/nitrogen-doped-silicon thin bi-layers

Energy Technology Data Exchange (ETDEWEB)

Abadli, S. [Department of Electrical Engineering, University Aout 1955, Skikda, 21000 (Algeria); LEMEAMED, Department of Electronics, University Mentouri, Constantine, 25000 (Algeria); Mansour, F. [LEMEAMED, Department of Electronics, University Mentouri, Constantine, 25000 (Algeria); Pereira, E. Bedel [CNRS-LAAS, 7 avenue du colonel Roche, 31077 Toulouse (France)

2012-10-15

We have investigated the complex behaviour of boron (B) redistribution process via silicon thin bi-layers interface. It concerns the instantaneous kinetics of B transfer, trapping, clustering and segregation during the thermal B activation annealing. The used silicon bi-layers have been obtained by low pressure chemical vapor deposition (LPCVD) method at 480 C, by using in-situ nitrogen-doped-silicon (NiDoS) layer and strongly B doped polycrystalline-silicon (P{sup +}) layer. To avoid long-range B redistributions, thermal annealing was carried out at relatively low-temperatures (600 C and 700 C) for various times ranging between 30 min and 2 h. To investigate the experimental secondary ion mass spectroscopy (SIMS) doping profiles, a redistribution model well adapted to the particular structure of two thin layers and to the effects of strong-concentrations has been established. The good adjustment of the simulated profiles with the experimental SIMS profiles allowed a fundamental understanding about the instantaneous physical phenomena giving and disturbing the complex B redistribution profiles-shoulders. The increasing kinetics of the B peak concentration near the bi-layers interface is well reproduced by the established model. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Nitrogen-doped ordered mesoporous carbon with a high surface area, synthesized through organic-inorganic coassembly, and its application in supercapacitors.

Science.gov (United States)

Song, Yanfang; Li, Li; Wang, Yonggang; Wang, Congxiao; Guo, Zaipin; Xia, Yongyao

2014-07-21

A new nitrogen-doped ordered mesoporous carbon (N-doped OMC) is synthesized by using an organic-inorganic coassembly method, in which resol is used as the carbon precursor, dicyandiamide as the nitrogen precursor, silicate oligomers as the inorganic precursors, and F127 as the soft template. The N-doped OMC possesses a surface area as high as 1374 m(2) g(-1) and a large pore size of 7.4 nm. As an electrode material for supercapacitors, the obtained carbon exhibits excellent cycling stability and delivers a reversible specific capacitance as high as 308 F g(-1) in 1 mol L(-1) H(2)SO(4) aqueous electrolyte, of which 58 % of the capacity is due to pseudo-capacitance. The large specific capacitance is attributed to proper pore size distributions, large surface area, and high nitrogen content. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Effect of doping of N and B atoms on thermoelectric properties of ...

Indian Academy of Sciences (India)

In this work, the doping effect on the thermoelectric properties of the C60 molecule ... mopower and thermal conductance of atomic sized metallic contacts, 1D wires, single ..... For negative energies, the sign of thermopower is positive while.
Three-Dimensional Nitrogen-Doped Hierarchical Porous Carbon as an Electrode for High-Performance Supercapacitors.

Science.gov (United States)

Tang, Jing; Wang, Tao; Salunkhe, Rahul R; Alshehri, Saad M; Malgras, Victor; Yamauchi, Yusuke

2015-11-23

A facile and sustainable procedure for the synthesis of nitrogen-doped hierarchical porous carbons with a three-dimensional interconnected framework (NHPC-3D) was developed. The strategy, based on a colloidal crystal-templating method, utilizes nitrogenous dopamine as the precursor due to its unique properties, including self-polymerization under mild alkaline conditions, coating onto various surfaces, a high carbonization yield, and well-preserved nitrogen doping after heat treatment. The obtained NHPC-3D possesses a high surface area of 1056 m(2) g(-1) , a large pore volume of 2.56 cm(3) g(-1) , and a high nitrogen content of 8.2 wt %. The NHPC-3D is implemented as the electrode material of a supercapacitor and exhibits a specific capacitance as high as 252 F g(-1) at a current density of 2 A g(-1) . The device also shows a high capacitance retention of 75.7 % at a higher current density of 20 A g(-1) in aqueous electrolyte due to a sufficient surface area for charge accommodation, reversible pseudocapacitance, and minimized ion-transport resistance, as a result of the advantageous interconnected hierarchical porous texture. These results showcase NHPC-3D as a promising candidate for electrode materials in supercapacitors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Synthesis of nitrogen-doped porous carbon nanofibers as an efficient electrode material for supercapacitors.

Science.gov (United States)

Chen, Li-Feng; Zhang, Xu-Dong; Liang, Hai-Wei; Kong, Mingguang; Guan, Qing-Fang; Chen, Ping; Wu, Zhen-Yu; Yu, Shu-Hong

2012-08-28

Supercapacitors (also known as ultracapacitors) are considered to be the most promising approach to meet the pressing requirements of energy storage. Supercapacitive electrode materials, which are closely related to the high-efficiency storage of energy, have provoked more interest. Herein, we present a high-capacity supercapacitor material based on the nitrogen-doped porous carbon nanofibers synthesized by carbonization of macroscopic-scale carbonaceous nanofibers (CNFs) coated with polypyrrole (CNFs@polypyrrole) at an appropriate temperature. The composite nanofibers exhibit a reversible specific capacitance of 202.0 F g(-1) at the current density of 1.0 A g(-1) in 6.0 mol L(-1) aqueous KOH electrolyte, meanwhile maintaining a high-class capacitance retention capability and a maximum power density of 89.57 kW kg(-1). This kind of nitrogen-doped carbon nanofiber represents an alternative promising candidate for an efficient electrode material for supercapacitors.
Effect of substrate temperature on the properties of pyrolytically deposited nitrogen-doped zinc oxide thin films

Energy Technology Data Exchange (ETDEWEB)

Golshahi, S., E-mail: golshahi@iaurasht.ac.ir [Department of Physics, Rasht Branch, Islamic Azad University, Rasht (Iran, Islamic Republic of); Rozati, S.M. [Department of Physics, University of Guilan, 41335-1914 Rasht (Iran, Islamic Republic of); Botelho do Rego, A.M. [Centro de Quimica-Fisica Molecular and IN, Technical University of Lisbon, IST 1049-001 Lisboa (Portugal); Wang, J. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Elangovan, E.; Martins, R.; Fortunato, E. [CENIMAT/I3N, Departamento de Ciencia dos Materiais, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa (UNL), 2829-516 Caparica (Portugal)

2013-01-01

Highlights: Black-Right-Pointing-Pointer Hall-effect measurement introduces the optimum temperature of 450 Degree-Sign C for fabricating p-type high quality ZnO films. Black-Right-Pointing-Pointer X-ray photoelectron spectroscopy (XPS) proved the nitrogen presence at the surface of doped ZnO thin films at all substrate temperatures. Black-Right-Pointing-Pointer Films prepared at lower substrate temperature (300 Degree-Sign C and 350 Degree-Sign C) own wider band gaps. Black-Right-Pointing-Pointer Surface roughness strongly is affected by substrate temperature variations. - Abstract: The effect of substrate temperature (T{sub s}) on the properties of pyrolytically deposited nitrogen (N) doped zinc oxide (ZnO) thin films was investigated. The T{sub s} was varied from 300 Degree-Sign C to 500 Degree-Sign C, with a step of 50 Degree-Sign C. The positive sign of Hall coefficient confirmed the p-type conductivity in the films deposited at 450 Degree-Sign C and 500 Degree-Sign C. X-ray diffraction studies confirmed the ZnO structure with a dominant peak from (1 0 0) crystal plane, irrespective of the variation in T{sub s}. The presence of N in the ZnO structure was evidenced through X-ray photoelectron spectroscopy (XPS) analysis. The obtained high N concentration reveals that the 450 Degree-Sign C is the optimal T{sub s}. Atomic force microscope (AFM) analysis showed that the surface roughness was increased with the increasing T{sub s} until 400 Degree-Sign C but then decreased. It is found that the transmittance of the deposited films is increased with the increasing T{sub s}. The optical band gap calculated from the absorption edge showed that the films deposited with T{sub s} of 300 Degree-Sign C and 350 Degree-Sign C possess higher values than those deposited at higher T{sub s}.
Effect of substrate temperature on the properties of pyrolytically deposited nitrogen-doped zinc oxide thin films

International Nuclear Information System (INIS)

Golshahi, S.; Rozati, S.M.; Botelho do Rego, A.M.; Wang, J.; Elangovan, E.; Martins, R.; Fortunato, E.

2013-01-01

Highlights: ► Hall-effect measurement introduces the optimum temperature of 450 °C for fabricating p-type high quality ZnO films. ► X-ray photoelectron spectroscopy (XPS) proved the nitrogen presence at the surface of doped ZnO thin films at all substrate temperatures. ► Films prepared at lower substrate temperature (300 °C and 350 °C) own wider band gaps. ► Surface roughness strongly is affected by substrate temperature variations. - Abstract: The effect of substrate temperature (T s ) on the properties of pyrolytically deposited nitrogen (N) doped zinc oxide (ZnO) thin films was investigated. The T s was varied from 300 °C to 500 °C, with a step of 50 °C. The positive sign of Hall coefficient confirmed the p-type conductivity in the films deposited at 450 °C and 500 °C. X-ray diffraction studies confirmed the ZnO structure with a dominant peak from (1 0 0) crystal plane, irrespective of the variation in T s . The presence of N in the ZnO structure was evidenced through X-ray photoelectron spectroscopy (XPS) analysis. The obtained high N concentration reveals that the 450 °C is the optimal T s . Atomic force microscope (AFM) analysis showed that the surface roughness was increased with the increasing T s until 400 °C but then decreased. It is found that the transmittance of the deposited films is increased with the increasing T s . The optical band gap calculated from the absorption edge showed that the films deposited with T s of 300 °C and 350 °C possess higher values than those deposited at higher T s .
Synergistic interaction and controllable active sites of nitrogen and sulfur co-doping into mesoporous carbon sphere for high performance oxygen reduction electrocatalysts

Science.gov (United States)

Oh, Taeseob; Kim, Myeongjin; Park, Dabin; Kim, Jooheon

2018-05-01

Nitrogen and sulfur co-doped mesoporous carbon sphere (NSMCS) was prepared as a metal-free catalyst by an economical and facile pyrolysis process. The mesoporous carbon spheres were derived from sodium carboxymethyl cellulose as the carbon source and the nitrogen and sulfur dopants were derived from urea and p-benzenedithiol, respectively. The doping level and chemical states of nitrogen and sulfur in the prepared NSMCS can be easily adjusted by controlling the pyrolysis temperature. The NSMCS pyrolyzed at 900 °C (NSMCS-900) exhibited higher oxygen reduction reaction activity than the mesoporous carbon sphere doped solely with nitrogen or sulfur, due to the synergistic effect of co-doping. Among all the NSMCS samples, NSMCS-900 exhibited excellent ORR catalytic activity owing to the presence of a highly active site, consisting of pyridinic N, graphitic N, and thiophene S. Remarkably, the NSMCS-900 catalyst was comparable with commercial Pt/C, in terms of the onset and the half-wave potentials and showed better durability than Pt/C for ORR in an alkaline electrolyte. The approach demonstrated in this work could be used to prepare promising metal-free electrocatalysts for application in energy conversion and storage.
Effect of working pressure on corrosion behavior of nitrogen doped diamond-like carbon thin films deposited by DC magnetron sputtering.

Science.gov (United States)

Khun, N W; Liu, E

2011-06-01

Nitrogen doped diamond-like carbon thin films were deposited on highly conductive p-silicon(100) substrates using a DC magnetron sputtering deposition system by varying working pressure in the deposition chamber. The bonding structure, adhesion strength, surface roughness and corrosion behavior of the films were investigated by using X-ray photoelectron spectroscopy, micro-Raman spectroscopy, micro-scratch test, atomic force microscopy and potentiodynamic polarization test. A 0.6 M NaCl electrolytic solution was used for the corrosion tests. The optimum corrosion resistance of the films was found at a working pressure of 7 mTorr at which a good balance between the kinetics of the sputtered ions and the surface mobility of the adatoms promoted a microstructure of the films with fewer porosities.
PtRu nanoparticles dispersed on nitrogen-doped carbon nanohorns as an efficient electrocatalyst for methanol oxidation reaction

International Nuclear Information System (INIS)

Zhang, Linwei; Gao, Ang; Liu, Yan; Wang, Yuan; Ma, Jiantai

2014-01-01

Highlights: • A novel anode catalyst is synthesized using N-doped carbon nanohorns as support. • PtRu/NCNHs exhibits an excellent activity for MOR relative to PtRu/C catalysts. • The enhancement is due to the electronic interaction between NCNHs and PtRu NPs. - Abstract: A novel anode catalyst (PtRu/NCNHs) assembled with nitrogen-doped carbon nanohorns (NCNHs) and PtRu nanoparticles (1.9 nm) exhibits an obvious enhancement in the tolerance to carbonaceous intermediates and the electocatalytic activity for methanol oxidation reaction (MOR) in comparison to a commercial PtRu/C-JM catalyst and a home-made PtRu/Vulcan catalyst. The MOR mass activity of PtRu/NCNHs (850 mA mg −1 PtRu ) is 2.5 times as high as that of PtRu/C-JM (341 mA mg −1 PtRu ). The MOR specific activity of PtRu/NCNHs is 1.8 times as high as that of PtRu/Vulcan having similar Pt/Ru atomic ratios, specific electrochemical surface areas and particle sizes of PtRu NPs. The electronic interaction between PtRu NPs and NCNHs is responsible for the enhancement in the MOR activity of PtRu/NCNHs
Highly efficient synthesis of ordered nitrogen-doped mesoporous carbons with tunable properties and its application in high performance supercapacitors

Science.gov (United States)

Liu, Dan; Zeng, Chao; Qu, Deyu; Tang, Haolin; Li, Yu; Su, Bao-Lian; Qu, Deyang

2016-07-01

Nitrogen-doped ordered mesoporous carbons (OMCs) have been synthesized via aqueous cooperative assembly route in the presence of basic amino acids as either polymerization catalysts or nitrogen dopants. This method allows the large-scale production of nitrogen-doped OMCs with tunable composition, structure and morphology while maintaining highly ordered mesostructures. For instances, the nitrogen content can be varied from ∼1 wt% to ∼6.3 wt% and the mesophase can be either 3-D body-centered cubic or 2-D hexagonal. The specific surface area for typical OMCs is around 600 m2 g-1, and further KOH activation can significantly enhance the surface area to 1866 m2 g-1 without destroying the ordered mesostructures. Benefiting from hierarchically ordered porous structure, nitrogen-doping effect and large-scale production availability, the synthesized OMCs show a great potential towards supercapacitor application. When measured in a symmetrical two-electrode configuration with an areal mass loading of ∼3 mg cm-2, the activated OMC exhibits high capacitance (186 F g-1 at 0.25 A g-1) and good rate capability (75% capacity retention at 20 A g-1) in ionic liquid electrolyte. Even as the mass loading is up to ∼12 mg cm-2, the OMC electrode still yields a specific capacitance of 126 F g-1 at 20 A g-1.
Controlled doping by self-assembled dendrimer-like macromolecules

Science.gov (United States)

Wu, Haigang; Guan, Bin; Sun, Yingri; Zhu, Yiping; Dan, Yaping

2017-02-01

Doping via self-assembled macromolecules might offer a solution for developing single atom electronics by precisely placing individual dopants at arbitrary location to meet the requirement for circuit design. Here we synthesize dendrimer-like polyglycerol macromolecules with each carrying one phosphorus atom in the core. The macromolecules are immobilized by the coupling reagent onto silicon surfaces that are pre-modified with a monolayer of undecylenic acid. Nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) are employed to characterize the synthesized macromolecules and the modified silicon surfaces, respectively. After rapid thermal annealing, the phosphorus atoms carried by the macromolecules diffuse into the silicon substrate, forming dopants at a concentration of 1017 cm-3. Low-temperature Hall effect measurements reveal that the ionization process is rather complicated. Unlike the widely reported simple ionization of phosphorus dopants, nitrogen and carbon are also involved in the electronic activities in the monolayer doped silicon.
Enhanced photocatalytic degradation of dye under visible light on mesoporous microspheres by defects in manganese- and nitrogen-co-doped TiO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Feng, Lu; Jiang, Heng, E-mail: hjiang78@hotmail.com [Liaoning Shihua University, School of Chemistry and Materials Science (China); Zou, Mingming; Xiong, Fengqiang; Ganeshraja, Ayyakannu Sundaram; Pervaiz, Erum [Chinese Academy of Sciences, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics (China); Liu, Yinan; Zou, Shunying [Dalian Environmental Protection Laboratory (China); Yang, Minghui, E-mail: myang@dicp.ac.cn [Chinese Academy of Sciences, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics (China)

2016-09-15

Manganese- and nitrogen-co-doped mesoporous TiO{sub 2} microsphere photocatalysts are prepared by a simple sol–gel method with controllable sizes in the range of 400–500 nm and high surface area of 112 m{sup 2} g{sup −1}. Manganous acetate is the Mn source, and ammonia gas is the nitrogen source used. The dopants are found to be uniformly distributed in the TiO{sub 2} matrix. Interestingly, in (Mn,N)-co-doped TiO{sub 2}, we observe an effective indirect band gap of ~2.58 eV. (Mn,N)-co-doped mesoporous TiO{sub 2} microspheres show higher photocatalytic activity than Mn–TiO{sub 2} microspheres under visible light irradiation. Among the samples reported in this work, 0.2 at.% Mn doping and 500 °C 2-h nitriding condition give the highest photocatalytic activity. The observed photocatalytic activity in the (Mn,N)-co-doped TiO{sub 2} is attributed to the contribution from improved absorption due to trap levels of Mn, oxygen vacancies and N doping.Graphical AbstractManganese- and nitrogen-co-doped mesoporous TiO{sub 2} microspheres containing substitutional N, interstitial N and O vacancies show high visible light photocatalytic activity.
Nitrogen-Doped Banana Peel–Derived Porous Carbon Foam as Binder-Free Electrode for Supercapacitors

OpenAIRE

Bingzhi Liu; Lili Zhang; Peirong Qi; Mingyuan Zhu; Gang Wang; Yanqing Ma; Xuhong Guo; Hui Chen; Boya Zhang; Zhuangzhi Zhao; Bin Dai; Feng Yu

2016-01-01

Nitrogen-doped banana peel?derived porous carbon foam (N-BPPCF) successfully prepared from banana peels is used as a binder-free electrode for supercapacitors. The N-BPPCF exhibits superior performance including high specific surface areas of 1357.6 m2/g, large pore volume of 0.77 cm3/g, suitable mesopore size distributions around 3.9 nm, and super hydrophilicity with nitrogen-containing functional groups. It can easily be brought into contact with an electrolyte to facilitate electron and io...
Oxygen- and nitrogen-co-doped activated carbon from waste particleboard for potential application in high-performance capacitance

International Nuclear Information System (INIS)

Shang, Tong-Xin; Ren, Ru-Quan; Zhu, Yue-Mei; Jin, Xiao-Juan

2015-01-01

Graphical abstract: All electrodes showed excellent capacitance and retention versus discharge current density from 0.05 to 5 A/g. - Abstract: Oxygen- and nitrogen-co-doped activated carbons were obtained from phosphoric acid treated nitrogen-doped activated carbons which were prepared from waste particleboard bonded with urea-formaldehyde resin adhesives. The activated carbon samples obtained were tested as supercapacitors in two-electrode cell and extensive wetting 7 M KOH electrolytes. Their structural properties and surface chemistry, before the electrical testing, were investigated using elemental analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, X-ray diffraction, Raman spectra, and adsorption of nitrogen. Activated carbon treated by 4 M phosphoric acid of the highest capacitance (235 F/g) was measured in spite of a relatively lower surface (1360 m 2 /g) than that of the activated carbon treated by 2 M phosphoric acid (1433 m 2 /g). The surface chemistry, and especially oxygen- and nitrogen-containing functional groups, was found of paramount importance for the capacitive behavior and for the effective pore space utilization by the electrolyte ions
Boron diffusion into nitrogen doped silicon films for P{sup +} polysilicon gate structures

Energy Technology Data Exchange (ETDEWEB)

Mansour, Farida; Mahamdi, Ramdane; Jalabert, Laurent; Temple-Boyer, Pierre

2003-06-23

This paper deals with the study of the boron diffusion in nitrogen doped silicon (NIDOS) deposited from disilane Si{sub 2}H{sub 6} and ammonia NH{sub 3} for the development of P{sup +} polysilicon gate metal oxide semiconductor (MOS) devices. NIDOS films with varied nitrogen content have been boron implanted, then annealed and finally analysed by secondary ion mass spectroscopy (SIMS). In order to simulate the experimental SIMS of boron concentration profiles in the NIDOS films, a model adapted to the particular conditions of the samples elaboration, i.e. the very high boron concentration and the nitrogen content, has been established. The boron diffusion reduction in NIDOS films with increasing nitrogen rates has been evidenced by the profiles as well as by the obtained diffusion coefficients, which shows that the nitrogen incorporation reduces the boron diffusion. This has been confirmed by capacitance-voltage (C-V) measurements performed on MOS capacitors: the higher the nitrogen content, the lower the flat-band voltage. Finally, these results demonstrate that the improvement of the gate oxide quality occurs with the suppression of the boron penetration.
Characterization of epitaxial GaAs MOS capacitors using atomic layer-deposited TiO2/Al2O3 gate stack: study of Ge auto-doping and p-type Zn doping.

Science.gov (United States)

Dalapati, Goutam Kumar; Shun Wong, Terence Kin; Li, Yang; Chia, Ching Kean; Das, Anindita; Mahata, Chandreswar; Gao, Han; Chattopadhyay, Sanatan; Kumar, Manippady Krishna; Seng, Hwee Leng; Maiti, Chinmay Kumar; Chi, Dong Zhi

2012-02-02

Electrical and physical properties of a metal-oxide-semiconductor [MOS] structure using atomic layer-deposited high-k dielectrics (TiO2/Al2O3) and epitaxial GaAs [epi-GaAs] grown on Ge(100) substrates have been investigated. The epi-GaAs, either undoped or Zn-doped, was grown using metal-organic chemical vapor deposition method at 620°C to 650°C. The diffusion of Ge atoms into epi-GaAs resulted in auto-doping, and therefore, an n-MOS behavior was observed for undoped and Zn-doped epi-GaAs with the doping concentration up to approximately 1017 cm-3. This is attributed to the diffusion of a significant amount of Ge atoms from the Ge substrate as confirmed by the simulation using SILVACO software and also from the secondary ion mass spectrometry analyses. The Zn-doped epi-GaAs with a doping concentration of approximately 1018 cm-3 converts the epi-GaAs layer into p-type since the Zn doping is relatively higher than the out-diffused Ge concentration. The capacitance-voltage characteristics show similar frequency dispersion and leakage current for n-type and p-type epi-GaAs layers with very low hysteresis voltage (approximately 10 mV).PACS: 81.15.Gh.
Photocatalytic equipment with nitrogen-doped titanium dioxide for air cleaning and disinfecting

International Nuclear Information System (INIS)

Le, Thanh Son; Ngo, Quoc Buu; Nguyen, Viet Dung; Nguyen, Hoai Chau; Dao, Trong Hien; Tran, Xuan Tin; Kabachkov, E N; Balikhin, I L

2014-01-01

Nitrogen-doped TiO 2 nanoparticle photocatalysts were synthesized by a sol–gel procedure using tetra-n-butyl orthotitanate as a titanium precursor and urea as a nitrogen source. Systematic studies for the preparation parameters and their impact on the material's structure were carried out by multiple techniques: thermogravimetric and differential scanning calorimetric analysis, x-ray diffraction, scanning electron microscope, transmission electron microscopy, energy dispersive x-ray spectroscopy and UV–Vis diffuse reflectance spectrophotometry showed that the nitrogen-doped TiO 2 calcined at 500 °C for 3 h exhibited a spherical form with a particle size about 15–20 nm and crystal phase presented a mixture of 89.12% anatase. The obtained product was deposited on a porous quartz tube (D = 74 mm; l = 418 mm) to manufacture an air photocatalytic cleaner as a prototype of the TIOKRAFT company's equipment. The created air cleaner was able to remove 60% of 10 ppm acetone within 390 min and degrade 98.5% of bacteria (total aerobic bacteria and fungi, 300 cfu m −3 ) within 120 min in a 10 m 3 box. These photodegradation activities of N-TiO 2 are higher than that of the commercial nano-TiO 2 (Skyspring Inc., USA, particle size of 5–10 nm). (paper)

Suppression of temperature instability in InGaZnO thin-film transistors by in situ nitrogen doping

International Nuclear Information System (INIS)

Raja, Jayapal; Jang, Kyungsoo; Yi, Junsin; Balaji, Nagarajan

2013-01-01

We have investigated the effect of nitrogen doping on the behavior of hysteresis curve and its suppression of temperature instability in amorphous InGaZnO thin-film transistors (a-IGZO TFTs). The in situ nitrogen doping reduced the temperature induced abnormal sub threshold leakage current and traps generation. Large falling-rate (F R ) ∼ 0.26 eV V −1 , low activation energy (E a ) ∼ 0.617 eV and a small hysteresis compared to the pure a-IGZO TFTs, shows the best immunity to thermal instability. This is mainly attributed to the reduction of interface trap density and oxygen vacancies due to the passivation of defects and/dangling bonds. (paper)
Heterogeneous photocatalytic degradation of toluene in static environment employing thin films of nitrogen-doped nano-titanium dioxide

Science.gov (United States)

Kannangara, Yasun Y.; Wijesena, Ruchira; Rajapakse, R. M. G.; de Silva, K. M. Nalin

2018-04-01

Photocatalytic semiconductor thin films have the ability to degrade volatile organic compounds (VOCs) causing numerous health problems. The group of VOCs called "BTEX" is abundant in houses and indoor of automobiles. Anatase phase of TiO2 has a band gap of 3.2 eV and UV radiation is required for photogeneration of electrons and holes in TiO2 particles. This band gap can be decreased significantly when TiO2 is doped with nitrogen (N-TiO2). Dopants like Pd, Cd, and Ag are hazardous to human health but N-doped TiO2 can be used in indoor pollutant remediation. In this research, N-doped TiO2 nano-powder was prepared and characterized using various analytical techniques. N-TiO2 was made in sol-gel method and triethylamine (N(CH2CH3)3) was used as the N-precursor. Modified quartz cell was used to measure the photocatalytic degradation of toluene. N-doped TiO2 nano-powder was illuminated with visible light (xenon lamp 200 W, λ = 330-800 nm, intensity = 1 Sun) to cause the degradation of VOCs present in static air. Photocatalyst was coated on a thin glass plate, using the doctor-blade method, was inserted into a quartz cell containing 2.00 µL of toluene and 35 min was allowed for evaporation/condensation equilibrium and then illuminated for 2 h. Remarkably, the highest value of efficiency 85% was observed in the 1 μm thick N-TiO2 thin film. The kinetics of photocatalytic degradation of toluene by N-TiO2 and P25-TiO2 has been compared. Surface topology was studied by varying the thickness of the N-TiO2 thin films. The surface nanostructures were analysed and studied with atomic force microscopy with various thin film thicknesses.
Growth feature of ionic nitrogen doped CN_x bilayer films with Ti and TiN interlayer by pulse cathode arc discharge

International Nuclear Information System (INIS)

Zhou, Bing; Liu, Zhubo; Piliptsou, D.G.; Rogachev, A.V.; Yu, Shengwang; Wu, Yanxia; Tang, Bin; Rudenkov, A.S.

2016-01-01

Graphical abstract: - Highlights: • Ti/ and TiN/CN_x (N"+) bilayers are prepared at various frequencies by pulse cathode arc. • Ti interlayer facilitates the introduction of N atoms into the CN_x (N"+) films. • The most N-sp"2C bonds (mainly graphite-like N) present in the TiN/CN_x (N"+, 3 Hz) film. • Ti/CN_x (N"+, 3 Hz) bilayer possesses small size and disordering of Csp"2 clusters. • The higher hardness and the lower stress presents in the TiN/CN_x (N"+, 10 Hz) bilayer. - Abstract: Using nano-scaled Ti and TiN as interlayer, ionic nitrogen doped carbon (CN_x (N"+)) bilayer films were prepared at various pulse frequencies by cathode arc technique. Elemental distribution at the interface, bonding compositions, microstructure, and mechanical properties of CN_x (N"+) bilayer films were investigated in dependence of interlayer and pulse frequency by Auger electron spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, nanoindentation, and surface profilometer. The results showed that the diffusion extent of C atoms at the interface of CN_x (N"+) bilayers is higher than for the α-C and CN_x (N_2) bilayers with the same interlayer. Nitrogen atoms could diffuse throughout the pre-deposited Ti and TiN layers into the Si substrate for all CN_x (N"+) bilayers. Ti interlayer facilitates the introduction of N atoms into the CN_x (N"+) films and exhibits a certain catalytic effect on the coordination of N atoms with sp"2- and sp"3-C binding. More nitrogenated and intense CN bonding configurations (mainly graphite-like N) form in the TiN/CN_x (N"+) bilayer. Ti/CN_x (N"+) bilayer prepared at low frequency possesses small size and disordering of Csp"2 clusters but TiN interlayer weakens the formation of Csp"2 bonding and increases the disordering of Csp"2 clusters in the films. The residual stress in the bilayer is lower than for CN_x (N"+) monolayer. The higher hardness and the lower residual stress are present in the TiN/CN_x (N"+, 10 Hz) bilayer.
Green synthesis of nitrogen-doped carbon dots from lotus root for Hg(II) ions detection and cell imaging

Energy Technology Data Exchange (ETDEWEB)

Gu, Dan; Shang, Shaoming, E-mail: smshang@jiangnan.edu.cn; Yu, Qin; Shen, Jie

2016-12-30

Graphical abstract: Fluorescent nitrogen-doped carbon dots were synthesized by a facile, green, and fast microwave method, using lotus root as carbon source. These nitrogen-doped carbon dots can be used for Hg{sup 2+} detection and cell imaging. - Highlights: • A green, fast strategy for synthesizing carbon dots was established. • A simple, sensitive, selective and wide linear range sensing of Hg{sup 2+} was developed. • The sensor system was demonstrated to detect Hg{sup 2+} in environmental water sample. • The carbon dots could serve for multicolor fluorescence bioimaging. - Abstract: Herein, a facile, green, and fast method was developed in the synthesis of fluorescent nitrogen-doped carbon dots (CDs) with nitrogen content of 5.23%, using one-pot microwave treatment of lotus root (LR), without using any other surface passivation agents. The results show that these LR-CDs (with an average diameter of 9.41 nm) possess many outstanding features and have a high quantum yield of 19.0%. We further demonstrated applications of LR-CDs as probes for heavy metal ion detection. The LR-CDs exhibit captivating sensitivity and selectivity toward Hg{sup 2+} with a linear range from 0.1 to 60.0 μM and a detection limit of 18.7 nM. Eventually, the LR-CDs were applied for multicolor cell imaging, demonstrating their potential toward diverse applications.
Enrichment of Pyrrolic Nitrogen by Hole Defects in Nitrogen and Sulfur Co-Doped Graphene Hydrogel for Flexible Supercapacitors.

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Tran, Ngoc Quang; Kang, Bong Kyun; Woo, Moo Hyun; Yoon, Dae Ho

2016-08-23

The effect of the doping configuration and concentration of nitrogen (N) and sulfur (S) on the electrochemical performance of 3 D N and S co-doped hole defect graphene hydrogel (NS-HGH) electrodes is investigated. Surprisingly, by introducing a hole defect on the graphene surface, the difference in the doping concentrations of N and S can be used to effectively modulate the electrochemical behavior of the NS-HGH. The hole defects provide a rapid ion diffusion path. Finally, we showed that the intriguing specific capacitance (536 F g(-1) ) of the NS-HGH could enhance the overall performance of the pseudocapacitance and electric double layer capacitance. The rational design of the NS-HGH-based flexible solid state supercapacitor results in not only outstanding electrochemical performance with a maximum energy density of 14.8 Wh kg(-1) and power density of 5.2 KW kg(-1) but also in extraordinary mechanical flexibility and excellent cycle stability. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Decorating Mg/Fe oxide nanotubes with nitrogen-doped carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Cao Yong, E-mail: caoyangel@126.com [Institute of Environment and Municipal Engineering, North China Institute of Water Conservancy and Hydroelectric Power, Zhengzhou 450011 (China); Jiao Qingze, E-mail: jiaoqz@bit.edu.cn [School of Chemical Engineering and the Environment, Beijing Institute of Technology, Beijing 100081 (China); Zhao Yun [School of Chemical Engineering and the Environment, Beijing Institute of Technology, Beijing 100081 (China); Dong Yingchao [Materials and Surface Science Institute (MSSI), University of Limerick, Limerick (Ireland)

2011-09-22

Graphical abstract: Highlights: > Mg/Fe oxide nanotubes arrayed parallel to each other were prepared by an AAO template method. > The Mg/Fe oxide nanotubes decorated with CN{sub x} were realized by CVD of ethylenediamine on the outer surface of oxide nanotubes. > The magnetic properties of Mg/Fe oxide nanotubes were highly improved after being decorated. - Abstract: Mg/Fe oxide nanotubes decorated with nitrogen-doped carbon nanotubes (CN{sub x}) were fabricated by catalytic chemical vapor deposition of ethylenediamine on the outer surface of oxide nanotubes. Mg/Fe oxide nanotubes were prepared using a 3:1 molar precursor solution of Mg(NO{sub 3}){sub 2} and Fe(NO{sub 3}){sub 3} and anodic aluminum oxide as the substrate. The obtained samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM). The XRD pattern shows that the oxide nanotubes are made up of MgO and Fe{sub 2}O{sub 3}. TEM and SEM observations indicate the oxide nanotubes are arrayed roughly parallel to each other, and the outer surface of oxide nanotubes are decorated with CN{sub x}. XPS results show the nitrogen-doped level in CN{sub x} is about 7.3 at.%. Magnetic measurements with VSM demonstrate the saturated magnetization, remanence and coercivity of oxide nanotubes are obvious improved after being decorated with CN{sub x}.
Hydrothermal synthesis of NiCo2O4 nanowires/nitrogen-doped graphene for high-performance supercapacitor

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Yu, Mei; Chen, Jianpeng; Ma, Yuxiao; Zhang, Jingdan; Liu, Jianhua; Li, Songmei; An, Junwei

2014-09-01

NiCo2O4 nanowires/nitrogen-doped graphene (NCO/NG) composite materials were synthesized by hydrothermal treatment in a water-glycerol mixed solvent and subsequent thermal transformation. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. The electrochemical performance of the composites was evaluated by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectrum techniques. NiCo2O4 nanowires are densely coated by nitrogen-doped graphene and the composite displays good electrochemical performance. The maximum specific capacitance of NCO/NG is 1273.13 F g-1 at 0.5 A g-1 in 6 M KOH aqueous solution, and it exhibits good capacity retention without noticeable degradation after 3000 cycles at 4 A g-1.
Photocatalytic activity and RNO dye degradation of nitrogen-doped TiO{sub 2} prepared by ionothermal synthesis

Energy Technology Data Exchange (ETDEWEB)

Pipi, Angelo; Ruotolo, Luis, E-mail: pluis@ufscar.br [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia Quimica; Byzynski, Gabriela [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Araraquara, SP (Brazil)

2017-05-15

This work concerns the preparation a nitrogen-doped TiO{sub 2} by ionothermal synthesis methods and the photocatalytic studies. In this procedure, alkoxide was used as a titanium source, and a deep eutectic mixture of choline chloride and urea (molar ratio 1:2) served as a solvent and source of nitrogen. Different samples were synthesized varying the percentages of the eutectic mixture, titanium butoxide, and water, as well as temperature and reaction time. The catalysts were characterized by X-ray diffraction, Raman spectrometry, scanning electron microscopy, and diffuse reflectance spectroscopy. N-doping was confirmed by X-ray photoelectron spectroscopy. The photocatalytic activity of the N-TiO{sub 2} nanoparticles was evaluated in the oxidation of N,N-dimethyl-4-nitrosoaniline (RNO) dye. The best photocatalytic activity under illumination by UV and visible light was found for the catalysts prepared under reflux in the presence of water, and for the catalysts prepared hydrothermally using intermediate percentages of the nitrogen source (the eutectic mixture). (author)
[Influence of deposition time on chromatics during nitrogen-doped diamond like carbon coating on pure titanium].

Science.gov (United States)

Yin, Lu; Yao, Jiang-wu; Xu, De-wen

2010-10-01

The aim of this study was to observed the influence of deposition time on chromatics during nitrogen-doped diamond like carbon coating (N-DLC) on pure titanium by multi impulse are plasma plating machine. Applying multi impulse are plasma plating machine to produce TiN coatings on pure titanium in nitrogen atmosphere, then filming with nitrogen-doped DLC on TiN in methane (10-80 min in every 5 min). The colors of N-DLC were evaluated in the CIE1976 L*a*b* uniform color scale and Mussell notation. The surface morphology of every specimen was analyzed using scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). When changing the time of N-DLC coating deposition, N-DLC surface showed different color. Golden yellow was presented when deposition time was 30 min. SEM showed that crystallization was found in N-DLC coatings, the structure changed from stable to clutter by varying the deposition time. The chromatics of N-DLC coatings on pure titanium could get golden yellow when deposition time was 30 min, then the crystallized structure was stable.
Liquid Phase Plasma Synthesis of Iron Oxide Nanoparticles on Nitrogen-Doped Activated Carbon Resulting in Nanocomposite for Supercapacitor Applications.

Science.gov (United States)

Lee, Heon; Lee, Won-June; Park, Young-Kwon; Ki, Seo Jin; Kim, Byung-Joo; Jung, Sang-Chul

2018-03-25

Iron oxide nanoparticles supported on nitrogen-doped activated carbon powder were synthesized using an innovative plasma-in-liquid method, called the liquid phase plasma (LPP) method. Nitrogen-doped carbon (NC) was prepared by a primary LPP reaction using an ammonium chloride reactant solution, and an iron oxide/NC composite (IONCC) was prepared by a secondary LPP reaction using an iron chloride reactant solution. The nitrogen component at 3.77 at. % formed uniformly over the activated carbon (AC) surface after a 1 h LPP reaction. Iron oxide nanoparticles, 40~100 nm in size, were impregnated homogeneously over the NC surface after the LPP reaction, and were identified as Fe₃O₄ by X-ray photoelectron spectroscopy and X-ray diffraction. NC and IONCCs exhibited pseudo-capacitive characteristics, and their specific capacitance and cycling stability were superior to those of bare AC. The nitrogen content on the NC surface increased the compatibility and charge transfer rate, and the composites containing iron oxide exhibited a lower equivalent series resistance.
Gas adsorption, energetics and electronic properties of boron- and nitrogen-doped bilayer graphenes

Energy Technology Data Exchange (ETDEWEB)

Fujimoto, Yoshitaka, E-mail: fujimoto@stat.phys.titech.ac.jp [Department of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro-ku, Tokyo 152-8551 (Japan); Saito, Susumu [Department of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro-ku, Tokyo 152-8551 (Japan); International Research Center for Nanoscience and Quantum Physics, Tokyo Institute of Technology, 2-12-1 Oh-okayama, Meguro-ku, Tokyo 152-8551 (Japan); Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503 (Japan)

2016-10-20

We study stabilities and electronic properties of several environmental polluting or toxic gas molecules (CO, CO{sub 2}, NO, and NO{sub 2}) adsorbed on B and N atoms in bilayer graphene using first-principles electronic-structure calculations. We find that NO and NO{sub 2} molecules can be bound chemically on B-doped bilayer graphene with large adsorption energies, while CO and CO{sub 2} molecules are not adsorbed chemically on B-doped one. In the case of the N-doped graphene, all four gases do not bind with chemical bonds but adsorb rather physically with small adsorption energies at long distances between gases and graphene. The adsorptions of NO and NO{sub 2} molecules on B-doped bilayer graphene induce the acceptor states above the Fermi energy, and we also find that the charge transfer takes place when the NO and the NO{sub 2} molecules are adsorbed. Thereby, the B-doped bilayer graphene is expected to be useful for NO and NO{sub 2} gas sensor materials.
Synthesis of biocompatible and highly photoluminescent nitrogen doped carbon dots from lime: Analytical applications and optimization using response surface methodology

Energy Technology Data Exchange (ETDEWEB)

Barati, Ali [Faculty of Chemistry, Institute for Advanced Studies in Basic Sciences, Zanjan (Iran, Islamic Republic of); Shamsipur, Mojtaba, E-mail: mshamsipur@yahoo.com [Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Arkan, Elham [Nano Drug Delivery Research Center Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of); Hosseinzadeh, Leila [Novel Drug Delivery Research Center, Faculty of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of); Abdollahi, Hamid, E-mail: abd@iasbs.ac.ir [Faculty of Chemistry, Institute for Advanced Studies in Basic Sciences, Zanjan (Iran, Islamic Republic of)

2015-02-01

Herein, a facile hydrothermal treatment of lime juice to prepare biocompatible nitrogen-doped carbon quantum dots (N-CQDs) in the presence of ammonium bicarbonate as a nitrogen source has been presented. The resulting N-CQDs exhibited excitation and pH independent emission behavior; with the quantum yield (QY) up to 40%, which was several times greater than the corresponding value for CQDs with no added nitrogen source. The N-CQDs were applied as a fluorescent probe for the sensitive and selective detection of Hg{sup 2+} ions with a detection limit of 14 nM. Moreover, the cellular uptake and cytotoxicity of N-CQDs at different concentration ranges from 0.0 to 0.8 mg/ml were investigated by using PC12 cells as a model system. Response surface methodology was used for optimization and systematic investigation of the main variables that influence the QY, including reaction time, reaction temperature, and ammonium bicarbonate weight. - Highlights: • High fluorescent N-doped CQDs from lime juice have been prepared. • Response surface methodology was used to optimize and model the main factors. • N-doped CQDs were used in the selective and sensitive detection of Hg(II). • The biocompatibility of prepared N-doped CQDs was conformed using PC12 cells.
Electrochemical oxidation of dihydronicotinamide adenine dinucleotide at nitrogen-doped carbon nanotube electrodes.

Science.gov (United States)

Goran, Jacob M; Favela, Carlos A; Stevenson, Keith J

2013-10-01

Nitrogen-doped carbon nanotubes (N-CNTs) substantially lower the overpotential necessary for dihydronicotinamide adenine dinucleotide (NADH) oxidation compared to nondoped CNTs or traditional carbon electrodes such as glassy carbon (GC). We observe a 370 mV shift in the peak potential (Ep) from GC to CNTs and another 170 mV shift from CNTs to 7.4 atom % N-CNTs in a sodium phosphate buffer solution (pH 7.0) with 2.0 mM NADH (scan rate 10 mV/s). The sensitivity of 7.4 atom % N-CNTs to NADH was measured at 0.30 ± 0.04 A M(-1) cm(-2), with a limit of detection at 1.1 ± 0.3 μM and a linear range of 70 ± 10 μM poised at a low potential of -0.32 V (vs Hg/Hg2SO4). NADH fouling, known to occur to the electrode surface during NADH oxidation, was investigated by measuring both the change in Ep and the resulting loss of electrode sensitivity. NADH degradation, known to occur in phosphate buffer, was characterized by absorbance at 340 nm and correlated with the loss of NADH electroactivity. N-CNTs are further demonstrated to be an effective platform for dehydrogenase-based biosensing by allowing glucose dehydrogenase to spontaneously adsorb onto the N-CNT surface and measuring the resulting electrode's sensitivity to glucose. The glucose biosensor had a sensitivity of 0.032 ± 0.003 A M(-1) cm(-2), a limit of detection at 6 ± 1 μM, and a linear range of 440 ± 50 μM.
A fluorescence probe based on the nitrogen-doped carbon dots prepared from orange juice for detecting Hg2+ in water

International Nuclear Information System (INIS)

Li, Zhili; Zhang, Ying; Niu, Qianqian; Mou, Mingyao; Wu, Yi; Liu, Xiaoxuan; Yan, Zhengyu; Liao, Shenghua

2017-01-01

An excellent biocompatible nitrogen-doped carbon dots (N-CDs) was successfully synthesized from orange juice and ethylenediamine by hydrothermal decomposition method. The as-prepared N-CDs were mono-dispersed spherical nanoparticles with a narrow size distribution of 0.5–3.0 nm and showed a good dispersion and stability in aqueous solution with the pH value ranging from 3.0 to 13.0. Photoluminescence spectra of as-prepared N-CDs demonstrated that the fluorescence intensity of N-CDs was increased with the doped nitrogen atoms and the FL-QY (fluorescence quantum yield) of N-CDs was up to 31.7%. Compared with Gly-CQDs(CQDs synthesied by Gly), which were prepared from chemical carbon source via hydrothermal decomposition method, the as-prepared N-CDs showed much lower cytotoxicity for Human THP-1 macrophage cells. These results indicated N-CDs prepared by our proposed method have excellent compatibility and more suitable for the application in biolabeling and bioimage. Due to the fluorescence quenching of N-CDs by mercury (II) ion (Hg 2+ ), a sensitive and selective method was developed for detecting Hg 2+ . The results indicated that the fluorescence intensity ratio of N-CDs was proportional to the concentration of Hg 2+ in the range from 4.0 μg/mL to 32.0 μg/mL and the recovery of spiked samples was ranged from 102.0% to 103.0%, which hinted our proposed method has a good sensitivity and accuracy and was suitable for detecting Hg 2+ with satisfactory in tap water.
Electrocatalytic analysis of superoxide anion radical using nitrogen-doped graphene supported Prussian Blue as a biomimetic superoxide dismutase

International Nuclear Information System (INIS)

Liu, Tingting; Niu, Xiangheng; Shi, Libo; Zhu, Xiang; Zhao, Hongli; Lana, Minbo

2015-01-01

Graphical abstract: Prussian Blue (PB) cubes supported on nitrogen-doped graphene sheets (NGS) were synthesized using a simple and scalable method, and the utilization of the PB-NGS hybrid as an efficient superoxide dismutase mimic in the electrochemical sensing of O 2 ·− was demonstrated. - Highlights: • Facile and scalable synthesis of Prussian Blue cubes supported on nitrogen-doped graphene; • Nitrogen-doped graphene supported Prussian Blue as an efficient biomimetic superoxide dismutase for the electrocatalytic sensing of superoxide anion; • Good sensitivity, excellent selectivity and attractive long-term stability for superoxide anion sensing. - Abstract: Considering the double-sided roles of superoxide anion radical, monitoring of its track in living systems is attracting increasing academic and practical interest. Here we synthesized Prussian Blue (PB) cubes that were supported on nitrogen-doped graphene sheets (NGS) using a facile and scalable method, and explored their potential utilization in the electrochemical sensing of superoxide anion. As an efficient superoxide dismutase mimic, direct electron transfer of the prepared PB-NGS hybrid immobilized on a screen-printed gold electrode was harvested in physiological media. With the bifunctional activities, the synthetic mimic could catalyze the dismutation of superoxide anion via the redox cycle of active iron. By capturing the electro-reduction amperometric responses of superoxide anion radical to hydrogen peroxide in the cathodic polarization, highly sensitive determination (a sensitivity of as high as 0.32 μA cm −2 μM −1 ) of the target was achieved, with no interference from common coexisting species including ascorbic acid, dopamine, and uric acid observed. Compared to natural superoxide dismutases, the artificial enzyme mimic exhibited favorable activity stability, indicating its promising applications in the in vivo long-term monitoring of superoxide anion
Advanced Sulfur Cathode Enabled by Highly Crumpled Nitrogen-Doped Graphene Sheets for High-Energy-Density Lithium-Sulfur Batteries.

Science.gov (United States)

Song, Jiangxuan; Yu, Zhaoxin; Gordin, Mikhail L; Wang, Donghai

2016-02-10

Herein, we report a synthesis of highly crumpled nitrogen-doped graphene sheets with ultrahigh pore volume (5.4 cm(3)/g) via a simple thermally induced expansion strategy in absence of any templates. The wrinkled graphene sheets are interwoven rather than stacked, enabling rich nitrogen-containing active sites. Benefiting from the unique pore structure and nitrogen-doping induced strong polysulfide adsorption ability, lithium-sulfur battery cells using these wrinkled graphene sheets as both sulfur host and interlayer achieved a high capacity of ∼1000 mAh/g and exceptional cycling stability even at high sulfur content (≥80 wt %) and sulfur loading (5 mg sulfur/cm(2)). The high specific capacity together with the high sulfur loading push the areal capacity of sulfur cathodes to ∼5 mAh/cm(2), which is outstanding compared to other recently developed sulfur cathodes and ideal for practical applications.
Quantification of Humic Substances in Natural Water Using Nitrogen-Doped Carbon Dots.

Science.gov (United States)

Guan, Yan-Fang; Huang, Bao-Cheng; Qian, Chen; Yu, Han-Qing

2017-12-19

Dissolved organic matter (DOM) is ubiquitous in aqueous environments and plays a significant role in pollutant mitigation, transformation and organic geochemical circulation. DOM is also capable of forming carcinogenic byproducts in the disinfection treatment processes of drinking water. Thus, efficient methods for DOM quantification are highly desired. In this work, a novel sensor for rapid and selective detection of humic substances (HS), a key component of DOM, based on fluorescence quenching of nitrogen-doped carbon quantum dots was developed. The experimental results show that the HS detection range could be broadened to 100 mg/L with a detection limit of 0.2 mg/L. Moreover, the detection was effective within a wide pH range of 3.0 to 12.0, and the interferences of ions on the HS measurement were negligible. A good detection result for real surface water samples further validated the feasibility of the developed detection method. Furthermore, a nonradiation electron transfer mechanism for quenching the nitrogen-doped carbon-dots fluorescence by HS was elucidated. In addition, we prepared a test paper and proved its effectiveness. This work provides a new efficient method for the HS quantification than the frequently used modified Lowry method in terms of sensitivity and detection range.
Amorphous Oxide Thin Film Transistors with Nitrogen-Doped Hetero-Structure Channel Layers

Directory of Open Access Journals (Sweden)

Haiting Xie

2017-10-01

Full Text Available The nitrogen-doped amorphous oxide semiconductor (AOS thinfilm transistors (TFTs with double-stacked channel layers (DSCL were prepared and characterized. The DSCL structure was composed of nitrogen-doped amorphous InGaZnO and InZnO films (a-IGZO:N/a-IZO:N or a-IZO:N/a-IGZO:N and gave the corresponding TFT devices large field-effect mobility due to the presence of double conduction channels. The a-IZO:N/a-IGZO:N TFTs, in particular, showed even better electrical performance (µFE = 15.0 cm2・V−1・s−1, SS = 0.5 V/dec, VTH = 1.5 V, ION/IOFF = 1.1 × 108 and stability (VTH shift of 1.5, −0.5 and −2.5 V for positive bias-stress, negative bias-stress, and thermal stress tests, respectively than the a-IGZO:N/a-IZO:N TFTs. Based on the X-ray photoemission spectroscopy measurements and energy band analysis, we assumed that the optimized interface trap states, the less ambient gas adsorption, and the better suppression of oxygen vacancies in the a-IZO:N/a-IGZO:N hetero-structures might explain the better behavior of the corresponding TFTs.
Carbon Nitrogen Co-Doped P25: Parameter Study on Photodegradation of Reactive Red 4

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Azami M. S.

2016-01-01

Full Text Available Photocatalytic degradation rate of reactive red 4 (RR4 using carbon coated nitrogen doped TiO2 (C N co-doped TiO2 in photocatalysis process is main goal on this research. The main operating the parameters such as effect of initial dye concentration, catalyst loading, aeration flow rate and initial pH on degradation of RR4 under 45 W fluorescent lamp was investigated. photocatalytic activity of RR4 dye decreased with increasing RR4 dye concentration. The optimum loading is around 0.04 g and optimum aeration rate is about 25 mL min-1 of C N co-doped TiO2. Effect of pH was conducted based on the optimum loading and conclude that the photocatalytic degradation of RR4 became faster at pH 2 - 7. For the future work, the modification of doping with others element like non-metal or metal with C N co-doped TiO2 can be enhanced toward the higher efficieny of photodegradation under visible light. Moreover, the immobilized technique can be used in future to overcome the difficulty of filtration on suspension.
Chemical Analysis of Impurity Boron Atoms in Diamond Using Soft X-ray Emission Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Muramatsu, Yasuji; Iihara, Junji; Takebe, Toshihiko; Denlinger, Jonathan D.

2008-03-29

To analyze the local structure and/or chemical states of boron atoms in boron-doped diamond, which can be synthesized by the microwave plasma-assisted chemical vapor deposition method (CVD-B-diamond) and the temperature gradient method at high pressure and high temperature (HPT-B-diamond), we measured the soft X-ray emission spectra in the CK and BK regions of B-diamonds using synchrotron radiation at the Advanced Light Source (ALS). X-ray spectral analyses using the fingerprint method and molecular orbital calculations confirm that boron atoms in CVD-B-diamond substitute for carbon atoms in the diamond lattice to form covalent B-C bonds, while boron atoms in HPT-B-diamond react with the impurity nitrogen atoms to form hexagonal boron nitride. This suggests that the high purity diamond without nitrogen impurities is necessary to synthesize p-type B-diamond semiconductors.

Nitrogen-doped amorphous carbon-silicon core-shell structures for high-power supercapacitor electrodes.

Science.gov (United States)

Tali, S A Safiabadi; Soleimani-Amiri, S; Sanaee, Z; Mohajerzadeh, S

2017-02-10

We report successful deposition of nitrogen-doped amorphous carbon films to realize high-power core-shell supercapacitor electrodes. A catalyst-free method is proposed to deposit large-area stable, highly conformal and highly conductive nitrogen-doped amorphous carbon (a-C:N) films by means of a direct-current plasma enhanced chemical vapor deposition technique (DC-PECVD). This approach exploits C 2 H 2 and N 2 gases as the sources of carbon and nitrogen constituents and can be applied to various micro and nanostructures. Although as-deposited a-C:N films have a porous surface, their porosity can be significantly improved through a modification process consisting of Ni-assisted annealing and etching steps. The electrochemical analyses demonstrated the superior performance of the modified a-C:N as a supercapacitor active material, where specific capacitance densities as high as 42 F/g and 8.5 mF/cm 2 (45 F/cm 3 ) on silicon microrod arrays were achieved. Furthermore, this supercapacitor electrode showed less than 6% degradation of capacitance over 5000 cycles of a galvanostatic charge-discharge test. It also exhibited a relatively high energy density of 2.3 × 10 3 Wh/m 3 (8.3 × 10 6 J/m 3 ) and ultra-high power density of 2.6 × 10 8 W/m 3 which is among the highest reported values.
Influence of Nitrogen Doping on Device Operation for TiO2-Based Solid-State Dye-Sensitized Solar Cells: Photo-Physics from Materials to Devices

Directory of Open Access Journals (Sweden)

Jin Wang

2016-02-01

Full Text Available Solid-state dye-sensitized solar cells (ssDSSC constitute a major approach to photovoltaic energy conversion with efficiencies over 8% reported thanks to the rational design of efficient porous metal oxide electrodes, organic chromophores, and hole transporters. Among the various strategies used to push the performance ahead, doping of the nanocrystalline titanium dioxide (TiO2 electrode is regularly proposed to extend the photo-activity of the materials into the visible range. However, although various beneficial effects for device performance have been observed in the literature, they remain strongly dependent on the method used for the production of the metal oxide, and the influence of nitrogen atoms on charge kinetics remains unclear. To shed light on this open question, we synthesized a set of N-doped TiO2 nanopowders with various nitrogen contents, and exploited them for the fabrication of ssDSSC. Particularly, we carefully analyzed the localization of the dopants using X-ray photo-electron spectroscopy (XPS and monitored their influence on the photo-induced charge kinetics probed both at the material and device levels. We demonstrate a strong correlation between the kinetics of photo-induced charge carriers probed both at the level of the nanopowders and at the level of working solar cells, illustrating a direct transposition of the photo-physic properties from materials to devices.
Pseudocapacitance of amorphous TiO2@nitrogen doped graphene composite for high rate lithium storage

International Nuclear Information System (INIS)

Li, Sheng; Xue, Pan; Lai, Chao; Qiu, Jingxia; Ling, Min; Zhang, Shanqing

2015-01-01

The high rate applications such as electric vehicles of the traditional lithium ion batteries (LIBs) are commonly limited by their insufficient electron conductivity and slow mass transport of lithium ions in bulk electrode materials. In order to address these issues, in this work, a simple and up-scalable wet-mechanochemical (wet-ball milling) route has been developed for fabrication of amorphous porous TiO 2 @nitrogen doped graphene (TiO 2 @N-G) nanocomposites. The amorphous phase, unique porous structure of TiO 2 and the surface defects from nitrogen doping to graphene planes have incurred surface controlled reactions, contributing pseudocapacitance to the total capacity of the battery. It plays a dominant role in producing outstanding high rate electrochemical performance, e.g., 182.7 mAh/g (at 3.36 A/g) after 100 cycles. The design and synthesis of electrode materials with enhanced conductivity and surface pseudocapacitance can be a promising way for high rate LIBs.
Three-dimensional Nitrogen-Doped Reduced Graphene Oxide/Carbon Nanotube Composite Catalysts for Vanadium Flow Batteries

Energy Technology Data Exchange (ETDEWEB)

Fu, Shaofang [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Zhu, Chengzhou [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Song, Junhua [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Engelhard, Mark H. [Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354 USA.; Du, Dan [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Lin, Yuehe [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354 USA.

2017-02-22

The development of vanadium redox flow battery is limited by the sluggish kinetics of the reaction, especially the cathodic VO2+/VO2+ redox couples. Therefore, it is vital to develop new electrocatalyst with enhanced activity to improve the battery performance. Herein, we first synthesized the hydrogel precursor by a facile hydrothermal method. After the following carbonization, nitrogen-doped reduced graphene oxide/carbon nanotube composite was obtained. By virtue of the large surface area and good conductivey, which are ensured by the unique hybrid structure, as well as the proper nitrogen doping, the as-prepared composite presents enhanced catalytic performance toward the VO2+/VO2+ redox reaction. We also demonstrated the composite with carbon nanotube loading of 2 mg/mL exhibits the highest activity and remarkable stability in aqueous solution due to the strong synergy between reduced graphene oxide and carbon nanotubes, indicating that this composite might show promising applications in vanadium redox flow battery.
Prussian blue-nitrogen-doped graphene nanocomposite as hybrid electrode for energy storage applications

International Nuclear Information System (INIS)

Sookhakian, M.; Basirun, W.J.; Teridi, Mohd Asri Mat; Mahmoudian, M.R.; Azarang, Majid; Zalnezhad, Erfan; Yoon, G.H.; Alias, Y.

2017-01-01

Highlights: • Novel and inexpensive Prussian blue-N-graphene composite for hybrid battery- supercapacitor. • Prussian blue leads to a significant increase of the capacity. • Prussian blue leads to enhancement of cycling stability of N-graphene. - Abstract: Water-soluble Prussian blue nanoparticles (PB NPs) supported on nitrogen-doped graphene (N-graphene) with high dispersion was fabricated for high performance energy storage hybrid electrodes. An efficient loading of the PB NPs and nitrogen doping of graphene were achieved. The structure and morphology of the composite was determined by X-ray diffraction, transmission electron microscopy, Raman spectrometry and X-ray photoelectron spectrometry. The energy storage performance was assessed by cyclic voltammetry and galvanostatic charge/discharge techniques. The nanocomposite was fabricated as a hybrid battery-supercapacitor electrode and exhibited excellent performance with the highest capacity of 660 C g −1 at 1 A g −1 , which was higher than pure PB NPs and N-graphene electrodes. Moreover, the synergistic effect of N-graphene and the PB NPs prevented the N-graphene from shrinking and swelling and increased the cycle stability to 84.7% retention after 1500 cycles at 6 A g −1 , compared to the pure N-graphene.
Nitrogen doped activated carbon from pea skin for high performance supercapacitor

Science.gov (United States)

Ahmed, Sultan; Ahmed, Ahsan; Rafat, M.

2018-04-01

In this work, nitrogen doped porous carbon (NDC) has been synthesized employing a facile two-step process. Firstly, carbon precursor (pea skin) was heated with melamine (acting as nitrogen source) followed by activation with KOH in different ratios. The dependence of porosity and nitrogen content on impregnation ratio was extensively studied. Other textural properties of prepared NDC sample were studied using standard techniques of material characterization. The electrochemical performance of NDC sample as an electrode was studied in two-electrode symmetric supercapacitor system. 1 M LiTFSI (lithium bis-trifluoromethanesulfonimide) solution in IL EMITFSI (1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide), was used as electrolyte. It was found that the fabricated supercapacitor cell offers high values of specific capacitance (141.1 F g‑1), specific energy (19.6 Wh kg‑1) and specific power (25.4 kW kg‑1) at current density of 1.3 A g‑1. More importantly, the fabricated supercapacitor cell shows capacitance retention of ∼75%, for more than 5000 cycles. The enhanced performance of NDC sample is primarily due to large surface area with favorable surface structure (contributing to double layer capacitance) and presence of nitrogen functionalities (contributing to pseudo-capacitance). Such important features make the synthesized NDC sample, an attractive choice for electrode material in high performance supercapacitor.
Nucleus-staining with biomolecule-mimicking nitrogen-doped carbon dots prepared by a fast neutralization heat strategy.

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Kang, Yan-Fei; Fang, Yang-Wu; Li, Yu-Hao; Li, Wen; Yin, Xue-Bo

2015-12-11

Biomolecule-mimicking nitrogen-doped carbon dots (N-Cdots) were synthesized from dopamine by a neutralization heat strategy. Fluorescence imaging of various cells validated their nucleus-staining efficiency. The dopamine-mimicking N-Cdots "trick" nuclear membranes to achieve nuclear localization and imaging.
Visible-light activity of N-LiInO{sub 2}: Band structure modifications through interstitial nitrogen doping

Energy Technology Data Exchange (ETDEWEB)

Xu, Kaiqiang [College of Material Science and Engineering, Hunan University, Changsha, 410082 (China); Xu, Difa, E-mail: xudifa@sina.com [Hunan Key Laboratory of Applied Environmental Photocatalysis, Changsha University, Changsha, 410022 (China); Zhang, Xiangchao; Luo, Zhuo; Wang, Yutang [Hunan Key Laboratory of Applied Environmental Photocatalysis, Changsha University, Changsha, 410022 (China); Zhang, Shiying, E-mail: cdzhangshiying@163.com [College of Material Science and Engineering, Hunan University, Changsha, 410082 (China); Hunan Key Laboratory of Applied Environmental Photocatalysis, Changsha University, Changsha, 410022 (China)

2017-01-01

Highlights: • The interstitial nitrogen doping into LiInO{sub 2} is achieved at low temperature. • The band gap narrowing to an extent of 2.8 eV from 3.5 eV is observed. • The doping favours charge carrier separation and photocatalytic activity. • Superoxide radical is the dominant active specie in the pollutant degradation. - Abstract: Element doping is a promising strategy to improve the photo-response and photocatalytic activity of semiconductor photocatalyst with a wide band gap. To reduce the band gap of LiInO{sub 2} that is considered as a novel photocatalyst, nitrogen-doped LiInO{sub 2} (N-LiInO{sub 2}) is successfully fabricated by treating LiInO{sub 2} and urea at 200 °C. It is found that interstitial instead of substitutional configurations are formed in the crystal structure of N-LiInO{sub 2} due to the low-treating temperature and rich-oxygen conditions. The interstitial N-doping forms a doping state with 0.6 eV above the valence band maximum and a defect state with 0.1 eV below the conduction band minimum, reducing the band gap of LiInO{sub 2} from 3.5 to 2.8 eV. N-LiInO{sub 2} exhibits higher photocatalytic activity towards methylene blue (MB) degradation under 380 nm light irradiation, which is 1.4 times that of pure LiInO{sub 2}. The enhanced photocatalytic activity of N-LiInO{sub 2} is attributed to the extended light absorption and the improved charge carrier separation, which result in more reactive species participating in the photcatalytic process. This work provides a further understanding on tuning the band structure of semiconductor photocatalyst by N-doping strategies.
Oxidation Properties of Nitrogen-Doped Silicon Films Deposited from Si2H6 and NH3

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Scheid, Emmanuel; Boyer, Pierre; Samitier, Josep; Hassani, Ahmed

1994-03-01

Si2H6/NH3 gas mixture was employed to obtain, by low-pressure chemical vapor deposition (LPCVD) at low temperature, nitrogen-doped silicon (NIDOS) films with various N/Si ratios. Thermal oxide was grown in dry oxygen at 900°C and 1100°C on NIDOS films. The result indicates that the nitrogen content of NIDOS films, assessed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR), greatly influences their oxidation rate.
Visible-light induced photocatalysis of AgCl@Ag/titanate nanotubes/nitrogen-doped reduced graphite oxide composites

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Pan, Hongfei; Zhao, Xiaona; Fu, Zhanming; Tu, Wenmao; Fang, Pengfei; Zhang, Haining

2018-06-01

High recombination rate of photogenerated electron-hole pairs and relatively narrow photoresponsive range of TiO2-based photocatalysts are the remaining challenges for their practical applications. To address such challenges, photocatalysts consisting of AgCl covered Ag nanoparticles (AgCl@Ag), titanate nanotubes (TiNT), and nitrogen-doped reduced graphite oxide (rGON) are fabricated through alkaline hydrothermal process, followed by deposition and in situ surface-oxidation of silver nanoparticles. In the synthesized photocatalysts, the titanate nanotubes have average length of about 100 nm with inner diameters of about 5 nm and the size of the formed silver nanoparticles is in the range of 50-100 nm. The synthesized photocatalyst degrades almost all the model organic pollutant Rhodamine B in 35 min and remains 90% of photocatalytic efficiency after 5 degradation cycles under visible light irradiation. Since the oxidant FeCl3 applied for oxidation of surface Ag to AgCl is difficult to be completely removed due to the high adsorption capacity of TiNT and rGON, the effect of reside Fe atoms on photocatalytic activity is evaluated and the results reveal that the residue Fe atom only affect the initial photodegradation performance. Nevertheless, the results demonstrate that the formed composite catalyst is a promising candidate for antibiosis and remediation in aquatic environmental contamination.
Transforming waste biomass with an intrinsically porous network structure into porous nitrogen-doped graphene for highly efficient oxygen reduction.

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Zhou, Huang; Zhang, Jian; Amiinu, Ibrahim Saana; Zhang, Chenyu; Liu, Xiaobo; Tu, Wenmao; Pan, Mu; Mu, Shichun

2016-04-21

Porous nitrogen-doped graphene with a very high surface area (1152 m(2) g(-1)) is synthesized by a novel strategy using intrinsically porous biomass (soybean shells) as a carbon and nitrogen source via calcination and KOH activation. To redouble the oxygen reduction reaction (ORR) activity by tuning the doped-nitrogen content and type, ammonia (NH3) is injected during thermal treatment. Interestingly, this biomass-derived graphene catalyst exhibits the unique properties of mesoporosity and high pyridine-nitrogen content, which contribute to the excellent oxygen reduction performance. As a result, the onset and half-wave potentials of the new metal-free non-platinum catalyst reach -0.009 V and -0.202 V (vs. SCE), respectively, which is very close to the catalytic activity of the commercial Pt/C catalyst in alkaline media. Moreover, our catalyst has a higher ORR stability and stronger CO and CH3OH tolerance than Pt/C in alkaline media. Importantly, in acidic media, the catalyst also exhibits good ORR performance and higher ORR stability compared to Pt/C.
Preparation of three-dimensional nitrogen-doped graphene layers by gas foaming method and its electrochemical capactive behavior

International Nuclear Information System (INIS)

Hao, Junnan; Shu, Dong; Guo, Songtao; Gao, Aimei; He, Chun; Zhong, Yayun; Liao, Yuqing; Huang, Yulan; Zhong, Jie

2016-01-01

Highlights: • A three-dimensional porous graphene layers was prepared via a gas foaming method. • Melamine was the nitrogen source to synthesize the N-doped 3D graphene layers. • The specific surface area of 3D N-doped graphene material is as high as 1196 m 2 g −1 . • The 3D N-doped graphene specific capacitance is 335 F g −1 in three-electrode system. • The energy density of 3D N-doped graphene reaches 58.1 Wh kg −1 in a symmetric cell. - Abstract: A porous graphene layers with a three-dimensional structure (3DG) was prepared via a gas foaming method based on a polymeric predecessor. This intimately interconnected 3DG structure not only significantly increases the specific surface area but also provides more channels to facilitate electron transport. In addition, 3D N-doped (3DNG) layers materials were synthesized using melamine as a nitrogen source. The nitrogen content in the 3DNG layers significantly influenced the electrochemical performance. The sample denoted as 3DNG-2 exhibited a specific capacitance of 335.2 F g −1 at a current density of 1 A g −1 in a three-electrode system. Additionally, 3DNG-2 exhibited excellent electrochemical performance in aqueous and organic electrolytes using a two-electrode symmetric cell. An energy density of 58.1 Wh kg −1 at a power density of 2500 W kg −1 was achieved, which is approximately 3 times that (19.6 Wh kg −1 ) in an aqueous electrolyte in a two-electrode system. After 1000 cycles, the capacity retention in aqueous electrolyte was more than 99.0%, and this retention in organic electrolytes was more than 89.4%, which demonstrated its excellent cycle stability. This performance makes 3DNG-2 a promising candidate as an electrode material in high-power and high-energy supercapacitor applications.
Three dimensional nitrogen-doped graphene aerogels functionalized with melamine for multifunctional applications in supercapacitors and adsorption

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Xing, Ling-Bao; Hou, Shu-Fen; Zhou, Jin; Zhang, Jing-Li; Si, Weijiang; Dong, Yunhui; Zhuo, Shuping

2015-10-01

In present work, we demonstrate an efficient and facile strategy to fabricate three-dimensional (3D) nitrogen-doped graphene aerogels (NGAs) based on melamine, which serves as reducing and functionalizing agent of graphene oxide (GO) in an aqueous medium with ammonia. Benefiting from well-defined and cross-linked 3D porous network architectures, the supercapacitor based on the NGAs exhibited a high specific capacitance of 170.5 F g-1 at 0.2 A g-1, and this capacitance also showed good electrochemical stability and a high degree of reversibility in the repetitive charge/discharge cycling test. More interestingly, the prepared NGAs further exhibited high adsorption capacities and high recycling performance toward several metal ions such as Pb2+, Cu2+ and Cd2+. Moreover, the hydrophobic carbonized nitrogen-doped graphene aerogels (CNGAs) showed outstanding adsorption and recycling performance for the removal of various oils and organic solvents.
Kinetic-limited etching of magnesium doping nitrogen polar GaN in potassium hydroxide solution

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Jiang, Junyan; Zhang, Yuantao; Chi, Chen; Yang, Fan; Li, Pengchong; Zhao, Degang; Zhang, Baolin; Du, Guotong

2016-01-01

KOH based wet etchings were performed on both undoped and Mg-doped N-polar GaN films grown by metal-organic chemical vapor deposition. It is found that the etching rate for Mg-doped N-polar GaN gets slow obviously compared with undoped N-polar GaN. X-ray photoelectron spectroscopy analysis proved that Mg oxide formed on N-polar GaN surface is insoluble in KOH solution so that kinetic-limited etching occurs as the etching process goes on. The etching process model of Mg-doped N-polar GaN in KOH solution is tentatively purposed using a simplified ideal atomic configuration. Raman spectroscopy analysis reveals that Mg doping can induce tensile strain in N-polar GaN films. Meanwhile, p-type N-polar GaN film with a hole concentration of 2.4 ÿ 1017 cm⿿3 was obtained by optimizing bis-cyclopentadienyl magnesium flow rates.
Locations of oxygen, nitrogen and carbon atoms in vanadium determined by neutron diffraction

International Nuclear Information System (INIS)

Hiraga, K.; Onozuka, T.; Hirabayashi, M.

1977-01-01

The occupation sites of oxygen, nitrogen, and carbon atoms dissolved interstitially in vanadium have been determined by means of neutron diffraction with use of single crystals of VOsub(0.032), VNsub(0.013) and VCsub(0.006). It is revealed that the interstitial atoms occupy, randomly, the octahedral sites in the b.c.c. host lattice of the three crystals. Neutron diffraction is advantageous for the present purpose, since the coherent scattering amplitudes of the solute atoms are much larger than that of the vanadium atom. (Auth.)
Preparation of raspberry-like γ-Fe2O3/crackled nitrogen-doped carbon capsules and their application as supports to improve catalytic activity.

Science.gov (United States)

Zhang, Junshuai; Yao, Tongjie; Zhang, Hui; Zhang, Xiao; Wu, Jie

2016-11-10

In this manuscript, we have introduced a novel method to improve the catalytic activity of metal nanoparticles via optimizing the support structure. To this end, raspberry-like γ-Fe 2 O 3 /crackled nitrogen-doped carbon (CNC) capsules were prepared by a two-step method. Compared with traditional magnetic capsules, in γ-Fe 2 O 3 /CNC capsules, the γ-Fe 2 O 3 nanoparticles were embedded in a CNC shell; therefore, they neither occupied the anchoring sites for metal nanoparticles nor came into contact with them, which was beneficial for increasing the metal nanoparticle loading. Numerous tiny cracks appeared on the porous CNC shell, which effectively improved the mass diffusion and transport in catalytic reactions. Additionally, the coordination interaction could be generated between the precursor metal ions and doped-nitrogen atoms in the capsule shell. With the help of these structural merits, γ-Fe 2 O 3 /CNC capsules were ideal supports for Pd nanoparticles, because they were beneficial for improving the Pd loading, reducing the nanoparticle size, increasing their dispersity and maximizing the catalytic performance of Pd nanoparticles anchored on the inner shell surface. As expected, γ-Fe 2 O 3 /CNC@Pd catalysts exhibited a dramatically enhanced catalytic activity towards hydrophilic 4-nitrophenol and hydrophobic nitrobenzene. The reaction rate constant k was compared with recent work and the corresponding reference samples. Moreover, they could be easily recycled by using a magnet and reused without an obvious loss of catalytic activity.
Nitrogen Doped Macroporous Carbon as Electrode Materials for High Capacity of Supercapacitor

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Yudong Li

2017-01-01

Full Text Available Nitrogen doped carbon materials as electrodes of supercapacitors have attracted abundant attention. Herein, we demonstrated a method to synthesize N-doped macroporous carbon materials (NMC with continuous channels and large size pores carbonized from polyaniline using multiporous silica beads as sacrificial templates to act as electrode materials in supercapacitors. By the nice carbonized process, i.e., pre-carbonization at 400 °C and then pyrolysis at 700/800/900/1000 °C, NMC replicas with high BET specific surface areas exhibit excellent stability and recyclability as well as superb capacitance behavior (~413 F ⋅ g−1 in alkaline electrolyte. This research may provide a method to synthesize macroporous materials with continuous channels and hierarchical pores to enhance the infiltration and mass transfer not only used as electrode, but also as catalyst somewhere micro- or mesopores do not work well.
In-depth nanocrystallization enhanced Li-ions batteries performance with nitrogen-doped carbon coated Fe3O4 yolk-shell nanocapsules

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Wu, Qianhui; Zhao, Rongfang; Liu, Wenjie; Zhang, Xiue; Shen, Xiao; Li, Wenlong; Diao, Guowang; Chen, Ming

2017-03-01

In this paper nitrogen-doped carbon-encapsulation Fe3O4 yolk-shell magnetic nanocapsules (Fe3O4@C-N nanocapsules) have been successfully constructed though a facile hydrothermal method and subsequent annealing process. Fe3O4 nanoparticles are completely enclosed in nitrogen-doped carbon shells with void space between the nanoparticle and the shell. The yolk-shell structure allows Fe3O4 nanoparticles to expand freely without breaking the outer carbon shell during the lithiation/delithiation processes. The volume expansion of Fe3O4 results in the in-depth nanocrystallization. Fortunately, the new generated small nanoparticles can increase the capability with the cycle increase due to the unique confinement effect and excellent electronic conductivity of the nitrogen-doped carbon shells. Hence, after 150 cycles, the discharge capacity of Fe3O4@C-N-700 nanocapsules still remained 832 mA h g-1 at 500 mA g-1, which corresponds to 116.7% of the lowest capacity (713 mA h g-1) at the 16th cycle. We believe that the yolk-shell structure is conducive to enhance the capacity of easy pulverization metal oxidation during the charge/discharge processes.
Sulfur and Nitrogen Co-Doped Graphene Electrodes for High-Performance Ionic Artificial Muscles.

Science.gov (United States)

Kotal, Moumita; Kim, Jaehwan; Kim, Kwang J; Oh, Il-Kwon

2016-02-24

Sulfur and nitrogen co-doped graphene electrodes for bioinspired ionic artificial muscles, which exhibit outstanding actuation performances (bending strain of 0.36%, 4.5 times higher than PSS electrodes, and 96% of initial strain after demonstration over 18 000 cycles), provide remarkable electro-chemo-mech anical properties: specific capacitance, electrical conductivity, and large surface area with mesoporosity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Co@Co3O4 nanoparticle embedded nitrogen-doped carbon architectures as efficient bicatalysts for oxygen reduction and evolution reactions

Science.gov (United States)

Qi, Chunling; Zhang, Li; Xu, Guancheng; Sun, Zhipeng; Zhao, Aihua; Jia, Dianzeng

2018-01-01

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play crucial roles in efficient energy conversion and storage solutions. Here, Co@Co3O4 nanoparticle embedded nitrogen-doped carbon architectures (denoted as Co@Co3O4/NCs) are prepared via a simple two-step and in situ approach by carbonization and subsequent oxidation of Co-MOF containing high contents of carbon and nitrogen. When evaluated as electrocatalyst towards both ORR and OER in a KOH electrolyte solution, the as-fabricated Co@Co3O4/NC-2 exhibits similar ORR catalytic activity to the commercial Pt/C catalyst, but superior stability and good methanol tolerance. Furthermore, the as-fabricated catalysts also show promising catalytic activity for OER. The effective catalytic activities originate from the synergistic effects between well wrapped Co@Co3O4 nanoparticles and nitrogen doped carbon structures.

Nitrogen-doped diamond electrode shows high performance for electrochemical reduction of nitrobenzene

International Nuclear Information System (INIS)

Zhang, Qing; Liu, Yanming; Chen, Shuo; Quan, Xie; Yu, Hongtao

2014-01-01

Highlights: • A metal-free nitrogen-doped diamond electrode was synthesized. • The electrode exhibits high electrocatalytic activity for nitrobenzene reduction. • The electrode exhibits high selectivity for reduction of nitrobenzene to aniline. • High energy efficiency was obtained compared with graphite electrode. -- Abstract: Effective electrode materials are critical to electrochemical reduction, which is a promising method to pre-treat anti-oxidative and bio-refractory wastewater. Herein, nitrogen-doped diamond (NDD) electrodes that possess superior electrocatalytic properties for reduction were fabricated by microwave-plasma-enhanced chemical vapor deposition technology. Nitrobenzene (NB) was chosen as the probe compound to investigate the material's electro-reduction activity. The effects of potential, electrolyte concentration and pH on NB reduction and aniline (AN) formation efficiencies were studied. NDD exhibited high electrocatalytic activity and selectivity for reduction of NB to AN. The NB removal efficiency and AN formation efficiency were 96.5% and 88.4% under optimal conditions, respectively; these values were 1.13 and 3.38 times higher than those of graphite electrodes. Coulombic efficiencies for NB removal and AN formation were 27.7% and 26.1%, respectively; these values were 4.70 and 16.6 times higher than those of graphite electrodes under identical conditions. LC–MS analysis revealed that the dominant reduction pathway on the NDD electrode was NB to phenylhydroxylamine (PHA) to AN
Negative differential resistance in BN co-doped coaxial carbon nanotube field effect transistor

Science.gov (United States)

Shah, Khurshed A.; Parvaiz, M. Shunaid

2016-12-01

The CNTFETs are the most promising advanced alternatives to the conventional FETs due to their outstanding structure and electrical properties. In this paper, we report the I-V characteristics of zig-zag (4, 0) semiconducting coaxial carbon nanotube field effect transistor (CNTFET) using the non-equilibrium Green's function formalism. The CNTFET is co-doped with two, four and six boron-nitrogen (BN) atoms separately near the electrodes using the substitutional doping method and the I-V characteristics were calculated for each model using Atomistic Tool Kit software (version 13.8.1) and its virtual interface. The results reveal that all models show negative differential resistance (NDR) behavior with the maximum peak to valley current ratio (PVCR) of 3.2 at 300 K for the four atom doped model. The NDR behavior is due to the band to band tunneling (BTBT) in semiconducting CNTFET and decreases as the doping in the channel increases. The results are beneficial for next generation designing of nano devices and their potential applications in electronic industry.
Ultra-high Rates and Reversible Capacity of Li-S Battery with a Nitrogen-doping Conductive Lewis Base Matrix

International Nuclear Information System (INIS)

Cao, Yong; Li, Xi-long; Zheng, Ming-sen; Yang, Mao-ping; Yang, Xu-lai; Dong, Quan-feng

2016-01-01

Highlights: • A polypyrrole/reduced graphene oxide (PPy/rGO) composite was prepared from in-situ hybridization of graphene oxide and pyrrole without additional oxidant. • Nitrogen doped graphene (NG) was obtained from the calcination of the PPy/rGO composite under 1500 °C and was confirmed with abundant pyridinic type nitrogen doping. • NG was employed as a conductive Lewis base matrix of sulfur cathode and the obtained composite cathode exhibited ultra-high rates and reversible capacity. • The excellent electrochemical performance can be attributed to the efficient adsorption of Li 2 S n (n=4-8) on the pyridinic-N enriched NG surface. - Abstract: To improve the electrochemical performance of lithium sulfur batteries, a conductive Lewis base matrix, nitrogen doped graphene (NG), was prepared here through a facile strategy of annealing a polypyrrole/reduced graphene oxide composite. The obtained NG was demonstrated with enriched pyridinic-N doping and was employed as the matrix of sulfur cathode with ultra-high rates, reversible capacity and high coulombic efficiency. The improved performance can be attributed to the high conductivity of the NG and the enhanced adsorption energy of Li 2 S n (n=4-8) on the NG surface. The NG can act not only as an electronic conductive network but also as a Lewis base “catalyst” matrix that promotes the higher Li 2 S n to be further oxidized completely to S 8 as demonstrated in the cyclic voltammetry curve, which can thus significantly improve the sulfur utilization and cyclic stability even at a high sulfur loading of 75% (w/w) in the S@NG composite.
Honeycomb-like Nitrogen and Sulfur Dual-Doped Hierarchical Porous Biomass-Derived Carbon for Lithium-Sulfur Batteries.

Science.gov (United States)

Chen, Manfang; Jiang, Shouxin; Huang, Cheng; Wang, Xianyou; Cai, Siyu; Xiang, Kaixiong; Zhang, Yapeng; Xue, Jiaxi

2017-04-22

Honeycomb-like nitrogen and sulfur dual-doped hierarchical porous biomass-derived carbon/sulfur composites (NSHPC/S) are successfully fabricated for high energy density lithium-sulfur batteries. The effects of nitrogen, sulfur dual-doping on the structures and properties of the NSHPC/S composites are investigated in detail by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and charge/discharge tests. The results show that N, S dual-doping not only introduces strong chemical adsorption and provides more active sites but also significantly enhances the electronic conductivity and hydrophilic properties of hierarchical porous biomass-derived carbon, thereby significantly enhancing the utilization of sulfur and immobilizing the notorious polysulfide shuttle effect. Especially, the as-synthesized NSHPC-7/S exhibits high initial discharge capacity of 1204 mA h g -1 at 1.0 C and large reversible capacity of 952 mA h g -1 after 300 cycles at 0.5 C with an ultralow capacity fading rate of 0.08 % per cycle even at high sulfur content (85 wt %) and high active material areal mass loading (2.8 mg cm -2 ) for the application of high energy density Li-S batteries. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Ultrathin nitrogen-doped graphitized carbon shell encapsulating CoRu bimetallic nanoparticles for enhanced electrocatalytic hydrogen evolution

Science.gov (United States)

Xu, You; Li, Yinghao; Yin, Shuli; Yu, Hongjie; Xue, Hairong; Li, Xiaonian; Wang, Hongjing; Wang, Liang

2018-06-01

Design of highly active and cost-effective electrocatalysts is very important for the generation of hydrogen by electrochemical water-splitting. Herein, we report the fabrication of ultrathin nitrogen-doped graphitized carbon shell encapsulating CoRu bimetallic nanoparticles (CoRu@NCs) and demonstrate their promising feasibility for efficiently catalyzing the hydrogen evolution reaction (HER) over a wide pH range. The resultant CoRu@NC nanohybrids possess an alloy–carbon core–shell structure with encapsulated low-ruthenium-content CoRu bimetallic alloy nanoparticles (10–30 nm) as the core and ultrathin nitrogen-doped graphitized carbon layers (2–6 layers) as the shell. Remarkably, the optimized catalyst (CoRu@NC-2 sample) with a Ru content as low as 2.04 wt% shows superior catalytic activity and excellent durability for HER in acidic, neutral, and alkaline conditions. This work offers a new method for the design and synthesis of non-platium-based electrocatalysts for HER in all-pH.
Sulfur and nitrogen co-doped carbon dots sensors for nitric oxide fluorescence quantification

Energy Technology Data Exchange (ETDEWEB)

Simões, Eliana F.C. [Centro de Investigação em Química da Universidade do Porto (CIQ-UP), Faculdade de Farmácia da Universidade de Coimbra, Pólo das Ciências da Saúde, 3000-548 Coimbra (Portugal); Centro de Investigação em Química da Universidade do Porto (CIQ-UP), Departamento de Geociências, Ambiente e Ordenamento do Território, Faculdade de Ciências da Universidade do Porto, R. Campo Alegre 687, 4169-007 Porto (Portugal); Leitão, João M.M., E-mail: jleitao@ff.uc.pt [Centro de Investigação em Química da Universidade do Porto (CIQ-UP), Faculdade de Farmácia da Universidade de Coimbra, Pólo das Ciências da Saúde, 3000-548 Coimbra (Portugal); Esteves da Silva, Joaquim C.G. [Centro de Investigação em Química da Universidade do Porto (CIQ-UP), Departamento de Geociências, Ambiente e Ordenamento do Território, Faculdade de Ciências da Universidade do Porto, R. Campo Alegre 687, 4169-007 Porto (Portugal)

2017-04-01

Microwave synthetized sulfur and nitrogen co-doped carbon dots responded selectively to nitric oxide (NO) at pH 7. Citric acid, urea and sodium thiosulfate in the proportion of 1:1:3 were used respectively as carbon, nitrogen and sulfur sources in the carbon dots microwave synthesis. For this synthesis, the three compounds were diluted in 15 mL of water and exposed for 5 min to a microwave radiation of 700 W. It is observed that the main factor contributing to the increased sensitivity and selectivity response to NO at pH 7 is the sodium thiosulfate used as sulfur source. A linear response range from 1 to 25 μM with a sensitivity of 16 μM{sup −1} and a detection limit of 0.3 μM were obtained. The NO quantification capability was assessed in standard and in fortified serum solutions. - Highlights: • S,N co-doped CDs were microwave synthetized from citric acid, urea and sodium thiosulfate. • The NO fluorescence sensing was evaluated at pH 7. • The selective and sensitive detection of NO at pH 7 was achieved. • Good NO quantification results in serum samples were obtained.
Sulfur and nitrogen co-doped carbon dots sensors for nitric oxide fluorescence quantification

International Nuclear Information System (INIS)

Simões, Eliana F.C.; Leitão, João M.M.; Esteves da Silva, Joaquim C.G.

2017-01-01

Microwave synthetized sulfur and nitrogen co-doped carbon dots responded selectively to nitric oxide (NO) at pH 7. Citric acid, urea and sodium thiosulfate in the proportion of 1:1:3 were used respectively as carbon, nitrogen and sulfur sources in the carbon dots microwave synthesis. For this synthesis, the three compounds were diluted in 15 mL of water and exposed for 5 min to a microwave radiation of 700 W. It is observed that the main factor contributing to the increased sensitivity and selectivity response to NO at pH 7 is the sodium thiosulfate used as sulfur source. A linear response range from 1 to 25 μM with a sensitivity of 16 μM"−"1 and a detection limit of 0.3 μM were obtained. The NO quantification capability was assessed in standard and in fortified serum solutions. - Highlights: • S,N co-doped CDs were microwave synthetized from citric acid, urea and sodium thiosulfate. • The NO fluorescence sensing was evaluated at pH 7. • The selective and sensitive detection of NO at pH 7 was achieved. • Good NO quantification results in serum samples were obtained.
Cement Pastes and Mortars Containing Nitrogen-Doped and Oxygen-Functionalized Multiwalled Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Mauricio Martínez-Alanis

2016-01-01

Full Text Available Cement pastes and mortars based on ordinary Portland cement containing nitrogen-doped multiwalled carbon nanotubes (MWCNT-Nx or oxygen-functionalized multiwalled carbon nanotubes (MWCNT-Ox are investigated. To incorporate MWCNTs into the cementitious matrix, the as-produced carpets are dispersed over periods of 1 and 2 hours in distilled water at pH levels of 1 and 7. The cement pastes are prepared by adding 0.1 wt% of MWCNTs to cement powder, followed by characterization with SEM and X-ray diffraction (XRD at an early age (first hours of hydration. The mortars are mechanically characterized during the hydration process for a period of 28 days. SEM characterization of cement pastes revealed that the carbon nanotubes are well incorporated in the cementitious matrix, with the hydrated cement grains interconnected by long carbon nanotubes. XRD characterizations demonstrated that, during the hydration of cement pastes, different peaks emerged that were associated with ettringite, hydrated calcium silicate, and calcium hydroxide, among other structures. Results of the compressive strength measurements for mortars simultaneously mixed with MWCNT-Nx and MWCNT-Ox reached an increment of approximately 30% in compressive strength. In addition, density functional theory calculations were performed in nitrogen-doped and oxygen-functionalized carbon nanotubes interacting with a cement grain.
Role of nitrogen distribution in asymmetric stone-wales defects on electronic transport of graphene nanoribbons

Energy Technology Data Exchange (ETDEWEB)

Zeng, Hui; Zhao, Jun; Xu, Dahai [College of Physical Science and Technology, Yangtze University, Jingzhou, Hubei 434023 (China); Wei, Jianwei [College of Optoelectronic Information, Chongqing University of Technology, Chongqing 400054 (China)

2012-01-15

The authors performed first principles calculation to investigate the influences of nitrogen dopant distribution in the asymmetric Stone-Wales (SW) defect on the electronic transport of zigzag-edged graphene nanoribbon (ZGNR). The stability of doped configurations are evaluated in terms of total energies. It is found that the dopant placed near the edge of the ribbon is the most energetically favorable site. Our results reveal that the doped nanostructures can be substantially modulated as a result of modifications on electronic bands induced by substitutional dopant. Moreover, the individual dopant gives rise to one or two complete electron backscattering centers associated with impurity states in the doped configurations, and the location is determined by the dopant site. Schematics of the atomic structure after asymmetric Stone-Wales defects introduced and different nitrogen substitutional sites. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Rod-like polyaniline supported on three-dimensional boron and nitrogen-co-doped graphene frameworks for high-performance supercapacitors

Science.gov (United States)

Liao, Kexuan; Gao, Jialu; Fan, Jinchen; Mo, Yao; Xu, Qunjie; Min, Yulin

2017-12-01

In this work, novel three-dimensional (3D) boron and nitrogen-co-doped three-dimensional (3D) graphene frameworks (BN-GFs) supporting rod-like polyaniline (PANI) are facilely prepared and used as electrodes for high-performance supercapacitors. The results demonstrated that BN-GFs with tuned electronic structure can not only provide a large surface area for rod-like PANI to anchor but also effectively facilitate the ion transfer and charge storage in the electrode. The PANI/BN-GF composite with wrinkled boron and nitrogen-co-doped graphene sheets interconnected by rod-like PANI exhibits excellent capacitive properties with a maximum specific capacitance of 596 F/g at a current density of 0.5 A/g. Notably, they also show excellent cycling stability with more than 81% capacitance retention after 5000 charge-discharge cycles.
Slow-light solitons in atomic media and doped optical fibers

International Nuclear Information System (INIS)

Korolkova, N.; Sinclair, G.F.; Leonhardt, U.

2005-01-01

Full text: We show how to generate optical solitons in atomic media that can be slowed down or accelerated at will. Such slow-light soliton is a polarization structure propagating with a speed that is proportional to the total intensity of the incident light. Ultimately, this method will allow the storage, retrieval and possibly the manipulation of the quantum information in atomic media. Solitons with controllable speed are constructed generalizing the theory of slow-light propagation to an integrable regime of nonlinear dynamics. For the first time, the inverse scattering method for slow-light solitons is developed. In contrast to the pioneering experimental demonstrations of slow light, we consider strong spin modulations where the non-linear dynamics of light and atoms creates polarization solitons. We also analyze how this scheme can be implemented in optical fibers doped with Lambda-atoms. In quantum-information applications, such slow-light solitons could complement the use of quantum solitons in fibres with the advantage of storing quantum information in media and complement methods for quantum memory with the advantages of non-linear dynamics, in particular the intrinsic stability of solitons. (author)
One-step synthesis of shell/core structural boron and nitrogen co-doped graphitic carbon/nanodiamond as efficient electrocatalyst for the oxygen reduction reaction in alkaline media

International Nuclear Information System (INIS)

Liu, Xiaoxu; Wang, Yanhui; Dong, Liang; Chen, Xi; Xin, Guoxiang; Zhang, Yan; Zang, Jianbing

2016-01-01

Shell/core structural boron and nitrogen co-doped graphitic carbon/nanodiamond (BN-C/ND) non-noble metal catalyst has been synthesized by a simple one-step heat-treatment of the mixture with nanodiamond, melamine, boric acid and FeCl 3 . In the process of the surface graphitization of nanodiamond with catalysis by FeCl 3 , B and N atoms from the decomposition of boric acid and melamine were directly introduced into the graphite lattice to form B, N co-doped graphitic carbon shell, while the core still retained the diamond structure. Electrochemical measurements of the BN-C/ND catalyst show much higher electrocatalytic activities towards oxygen reduction reaction (ORR) in alkaline medium than its analogues doped with B or N alone (B-C/ND or N-C/ND). The high catalytic activity of BN-C/ND is attributed to the synergetic effect caused by co-doping of C/ND with B and N. Meanwhile, the BN-C/ND exhibits an excellent electrochemical stability due to the special shell/core structure. There is almost no alteration occurred in the cyclic voltammetry measurements for BN-C/ND before and after 5000 cycles. All experimental results prove that the BN-C/ND may be exploited as a potentially efficient and inexpensive non-noble metal cathode catalyst for ORR to substitute Pt-based catalysts in fuel cells.
Nitrogen-doped porous carbon monoliths from polyacrylonitrile (PAN) and carbon nanotubes as electrodes for supercapacitors

Science.gov (United States)

Wang, Yanqing; Fugetsu, Bunshi; Wang, Zhipeng; Gong, Wei; Sakata, Ichiro; Morimoto, Shingo; Hashimoto, Yoshio; Endo, Morinobu; Dresselhaus, Mildred; Terrones, Mauricio

2017-01-01

Nitrogen-doped porous activated carbon monoliths (NDP-ACMs) have long been the most desirable materials for supercapacitors. Unique to the conventional template based Lewis acid/base activation methods, herein, we report on a simple yet practicable novel approach to production of the three-dimensional NDP-ACMs (3D-NDP-ACMs). Polyacrylonitrile (PAN) contained carbon nanotubes (CNTs), being pre-dispersed into a tubular level of dispersions, were used as the starting material and the 3D-NDP-ACMs were obtained via a template-free process. First, a continuous mesoporous PAN/CNT based 3D monolith was established by using a template-free temperature-induced phase separation (TTPS). Second, a nitrogen-doped 3D-ACM with a surface area of 613.8 m2/g and a pore volume 0.366 cm3/g was obtained. A typical supercapacitor with our 3D-NDP-ACMs as the functioning electrodes gave a specific capacitance stabilized at 216 F/g even after 3000 cycles, demonstrating the advantageous performance of the PAN/CNT based 3D-NDP-ACMs. PMID:28074847
Undoped and doped poly(tetraphenylbenzidine) as sensitive material for an impedimetric nitrogen dioxide gas dosimeter

Energy Technology Data Exchange (ETDEWEB)

Marr, I.; Moos, R., E-mail: functional.materials@uni-bayreuth.de [Department of Functional Materials, University of Bayreuth, Bayreuth 95440 (Germany); Neumann, K.; Thelakkat, M. [Department of Macromolecular Chemistry I, Applied Functional Polymers, University of Bayreuth, Bayreuth 95440 (Germany)

2014-09-29

This article presents a nitrogen dioxide (NO{sub 2}) detecting gas dosimeter based on poly(tetraphenylbenzidine) poly(TPD) as nitrogen oxide (NO{sub x}) sensitive layer. Gas dosimeters are suitable devices to determine reliably low levels of analytes over a long period of time. During NO{sub x} exposure, the analyte molecules are accumulated irreversibly in the sensing layer of the dosimeter enhancing the conductivity of the hole conducting poly(TPD), which can be measured by impedance spectroscopy. Due to their possibility for low cost production by simple printing techniques and very good physical, photochemical, and electrochemical properties, poly(TPD)s are suitable for application in gas dosimeters operated at room temperature. We studied the effect of doping with a Co(III)-complex in combination with a conducting salt on the dosimeter behavior. Compared to the undoped material, a strong influence of the doping can be observed: the conductivity of the sensing material increases significantly, the noise of the signal decreases and an unwanted recovery of the sensor signal can be prevented, leading to a NO{sub x} detection limit <10 ppm.
Nitrogen-doped porous carbon monoliths from polyacrylonitrile (PAN) and carbon nanotubes as electrodes for supercapacitors.

Science.gov (United States)

Wang, Yanqing; Fugetsu, Bunshi; Wang, Zhipeng; Gong, Wei; Sakata, Ichiro; Morimoto, Shingo; Hashimoto, Yoshio; Endo, Morinobu; Dresselhaus, Mildred; Terrones, Mauricio

2017-01-11

Nitrogen-doped porous activated carbon monoliths (NDP-ACMs) have long been the most desirable materials for supercapacitors. Unique to the conventional template based Lewis acid/base activation methods, herein, we report on a simple yet practicable novel approach to production of the three-dimensional NDP-ACMs (3D-NDP-ACMs). Polyacrylonitrile (PAN) contained carbon nanotubes (CNTs), being pre-dispersed into a tubular level of dispersions, were used as the starting material and the 3D-NDP-ACMs were obtained via a template-free process. First, a continuous mesoporous PAN/CNT based 3D monolith was established by using a template-free temperature-induced phase separation (TTPS). Second, a nitrogen-doped 3D-ACM with a surface area of 613.8 m 2 /g and a pore volume 0.366 cm 3 /g was obtained. A typical supercapacitor with our 3D-NDP-ACMs as the functioning electrodes gave a specific capacitance stabilized at 216 F/g even after 3000 cycles, demonstrating the advantageous performance of the PAN/CNT based 3D-NDP-ACMs.
Hydrothermal synthesis of two photoluminescent nitrogen-doped graphene quantum dots emitted green and khaki luminescence

International Nuclear Information System (INIS)

Zhu, Xiaohua; Zuo, Xiaoxi; Hu, Ruiping; Xiao, Xin; Liang, Yong; Nan, Junmin

2014-01-01

A simple and effective chemical synthesis of the photoluminescent nitrogen-doped graphene quantum dots (N-GQDs) biomaterial is reported. Using the hydrothermal treatment of graphene oxide (GO) in the presence of hydrogen peroxide (H 2 O 2 ) and ammonia, the N-GQDs are synthesized through H 2 O 2 exfoliating the GO into nanocrystals with lateral dimensions and ammonia passivating the generated active surface. Then, after a dialytic separation, two water-soluble N-GQDs with average size of about 2.1 nm/6.2 nm, which emit green/khaki luminescence and exhibit excitation dependent/independent photoluminescence (PL) behaviors, are obtained. In addition, it is also demonstrated that these two N-GQDs are stable over a broad pH range and have the upconversion PL property, showing this approach provides a simple and effective method to synthesize the functional N-GQDs. - Highlights: • Nitrogen-doped graphene quantum dots (N-GQDs) are prepared by hydrothermal routine. • Two N-GQDs with different size distribution emit green/khaki photoluminescence. • Two N-GQDs exhibit excitation-dependent/independent photoluminescence behaviors
Kinetic-limited etching of magnesium doping nitrogen polar GaN in potassium hydroxide solution

International Nuclear Information System (INIS)

Jiang, Junyan; Zhang, Yuantao; Chi, Chen; Yang, Fan; Li, Pengchong; Zhao, Degang; Zhang, Baolin; Du, Guotong

2016-01-01

Graphical abstract: - Highlights: • Effects of Mg doping on wet etching of N-polar GaN are illustrated and analysed. • Etching process model of Mg-doped N-polar GaN in KOH solution is purposed. • It is found that Mg doping can induce tensile strain in N-polar GaN film. • N-polar p-GaN film with a hole concentration of 2.4 × 10"1"7 cm"−"3 is obtained. - Abstract: KOH based wet etchings were performed on both undoped and Mg-doped N-polar GaN films grown by metal-organic chemical vapor deposition. It is found that the etching rate for Mg-doped N-polar GaN gets slow obviously compared with undoped N-polar GaN. X-ray photoelectron spectroscopy analysis proved that Mg oxide formed on N-polar GaN surface is insoluble in KOH solution so that kinetic-limited etching occurs as the etching process goes on. The etching process model of Mg-doped N-polar GaN in KOH solution is tentatively purposed using a simplified ideal atomic configuration. Raman spectroscopy analysis reveals that Mg doping can induce tensile strain in N-polar GaN films. Meanwhile, p-type N-polar GaN film with a hole concentration of 2.4 × 10"1"7 cm"−"3 was obtained by optimizing bis-cyclopentadienyl magnesium flow rates.
Kinetic-limited etching of magnesium doping nitrogen polar GaN in potassium hydroxide solution

Energy Technology Data Exchange (ETDEWEB)

Jiang, Junyan; Zhang, Yuantao; Chi, Chen; Yang, Fan; Li, Pengchong [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Qianjin Street 2699, Changchun 130012 (China); Zhao, Degang [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Science, PO Box 912, Beijing 100083 (China); Zhang, Baolin; Du, Guotong [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Qianjin Street 2699, Changchun 130012 (China)

2016-01-01

Graphical abstract: - Highlights: • Effects of Mg doping on wet etching of N-polar GaN are illustrated and analysed. • Etching process model of Mg-doped N-polar GaN in KOH solution is purposed. • It is found that Mg doping can induce tensile strain in N-polar GaN film. • N-polar p-GaN film with a hole concentration of 2.4 × 10{sup 17} cm{sup −3} is obtained. - Abstract: KOH based wet etchings were performed on both undoped and Mg-doped N-polar GaN films grown by metal-organic chemical vapor deposition. It is found that the etching rate for Mg-doped N-polar GaN gets slow obviously compared with undoped N-polar GaN. X-ray photoelectron spectroscopy analysis proved that Mg oxide formed on N-polar GaN surface is insoluble in KOH solution so that kinetic-limited etching occurs as the etching process goes on. The etching process model of Mg-doped N-polar GaN in KOH solution is tentatively purposed using a simplified ideal atomic configuration. Raman spectroscopy analysis reveals that Mg doping can induce tensile strain in N-polar GaN films. Meanwhile, p-type N-polar GaN film with a hole concentration of 2.4 × 10{sup 17} cm{sup −3} was obtained by optimizing bis-cyclopentadienyl magnesium flow rates.
First-principles study on the interaction of nitrogen atom with α–uranium: From surface adsorption to bulk diffusion

International Nuclear Information System (INIS)

Su, Qiulei; Deng, Huiqiu; Xiao, Shifang; Li, Xiaofan; Hu, Wangyu; Ao, Bingyun; Chen, Piheng

2014-01-01

Experimental studies of nitriding on uranium surfaces show that the modified layers provide considerable protection against air corrosion. The bimodal distribution of nitrogen is affected by both its implantation and diffusion, and the diffusion of nitrogen during implantation is also governed by vacancy trapping. In the present paper, nitrogen adsorption, absorption, diffusion, and vacancy trapping on the surface of and in the bulk of α–uranium are studied with a first-principles density functional theory approach and the climbing image nudged elastic band method. The calculated results indicate that, regardless of the nitrogen coverage, a nitrogen atom prefers to reside at the hollow1 site and octahedral (Oct) site on and below the surface, respectively. The lowest energy barriers for on-surface and penetration diffusion occur at a coverage of 1/2 monolayer. A nitrogen atom prefers to occupy the Oct site in bulk α–uranium. High energy barriers are observed during the diffusion between neighboring Oct sites. A vacancy can capture its nearby interstitial nitrogen atom with a low energy barrier, providing a significant attractive nitrogen-vacancy interaction at the trapping center site. This study provides a reference for understanding the nitriding process on uranium surfaces
Investigation of hydrogen peroxide reduction reaction on graphene and nitrogen doped graphene nanoflakes in neutral solution

Science.gov (United States)

Amirfakhri, Seyed Javad; Binny, Dustin; Meunier, Jean-Luc; Berk, Dimitrios

2014-07-01

H2O2 reduction reaction (HPRR) is studied on both graphene (GNF) and nitrogen doped graphene nanoflakes in 0.1 M Na2SO4 solution by rotating disk electrode. The XPS results indicate that N-doped graphene nanoflakes with high nitrogen content, 32 at%N (N-GNF32), are synthesised successfully by an inductively-coupled thermal plasma (ICP) reactor. Pyridinic, pyrrolic and graphitic N species contribute up to 67% of the total nitrogen. Kinetic parameters such as Tafel slope and stoichiometric number suggest that HPRR occurs by the same mechanism on both GNF and N-GNF32. Although nitrogen does not change the mechanism of HPRR, the results indicate that the reaction rate of H2O2 reduction is enhanced on N-GNF32. The exchange current density of H2O2 reduction based on the active surface area of N-GNF32 is (8.3 ± 0.3) × 10-9 A cm-2, which is 6 times higher than the value determined for GNF. The apparent number of electrons involved in the process suggests that H2O2 decomposition competes with H2O2 reduction on both catalysts. Evaluation of the apparent heterogeneous reaction rate constant and the Tafel slope indicate that simultaneous reduction of O2 and H2O2 is negligible on the N-GNF32. On the other hand, the reduction of O2 and H2O2 occurs simultaneously on the GNF surface.

Osmium Atoms and Os2 Molecules Move Faster on Selenium-Doped Compared to Sulfur-Doped Boronic Graphenic Surfaces.

Science.gov (United States)

Barry, Nicolas P E; Pitto-Barry, Anaïs; Tran, Johanna; Spencer, Simon E F; Johansen, Adam M; Sanchez, Ana M; Dove, Andrew P; O'Reilly, Rachel K; Deeth, Robert J; Beanland, Richard; Sadler, Peter J

2015-07-28

We deposited Os atoms on S- and Se-doped boronic graphenic surfaces by electron bombardment of micelles containing 16e complexes [Os(p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-diselenate/dithiolate)] encapsulated in a triblock copolymer. The surfaces were characterized by energy-dispersive X-ray (EDX) analysis and electron energy loss spectroscopy of energy filtered TEM (EFTEM). Os atoms moved ca. 26× faster on the B/Se surface compared to the B/S surface (233 ± 34 pm·s(-1) versus 8.9 ± 1.9 pm·s(-1)). Os atoms formed dimers with an average Os-Os distance of 0.284 ± 0.077 nm on the B/Se surface and 0.243 ± 0.059 nm on B/S, close to that in metallic Os. The Os2 molecules moved 0.83× and 0.65× more slowly than single Os atoms on B/S and B/Se surfaces, respectively, and again markedly faster (ca. 20×) on the B/Se surface (151 ± 45 pm·s(-1) versus 7.4 ± 2.8 pm·s(-1)). Os atom motion did not follow Brownian motion and appears to involve anchoring sites, probably S and Se atoms. The ability to control the atomic motion of metal atoms and molecules on surfaces has potential for exploitation in nanodevices of the future.
DFT study of stabilization effects on N-doped graphene for ORR catalysis

DEFF Research Database (Denmark)

Reda, Mateusz; Hansen, Heine Anton; Vegge, Tejs

2018-01-01

Noble metal free catalysts, such as N-doped graphene, have drawn a lot of attention as a promising replacement for platinum in low temperature fuel cells. Computational prediction of catalytic activity requires accurate description of the oxygen reduction reaction (ORR) intermediates adsorption...... energies. Two stabilizing effects, immanently present in experimental ORR setups with basal plane N-doped graphene catalyst, are studied systematically by means of density functional theory. Distant nitrogen with no adsorbates on neighboring carbon atoms selectively stabilizes *O and *O2 adsorbates. Water...... solvation stabilizes all ORR intermediates, having a greater impact on *O and *O2, than on *OH and *OOH, in contrast to metal and oxide catalysts. Synergistic stabilization of *O caused by both effects reaches remarkably a high value of 1.5 eV for nitrogen concentrations above 4.2% N. Such a strong effect...
Effect of substrate roughness and working pressure on photocatalyst of N-doped TiOx films prepared by reactive sputtering with air

International Nuclear Information System (INIS)

Lee, Seon-Hong; Yamasue, Eiji; Okumura, Hideyuki; Ishihara, Keiichi N.

2015-01-01

Highlights: • Effect of substrate roughness and working pressure on the physical properties and the photocatalytic properties of the N-doped TiO x films are investigated. • Surface roughness of glass substrate has little influence on the film properties, but significant influence on the photocatalytic ability. • Working pressure has little influence on the produced phases and the atomic bonding configurations, but significant influence on the atomic concentration of the N-doped TiO x film. • High photocatalysis of N-doped TiO x film requires the permissible range of the N doping concentration which shows the interstitial complex N doping states in TiO 2 . - Abstract: N-doped TiO x films on the glass substrate were prepared by radio-frequency (RF) magnetron reactive sputtering of Ti target in a mixed gas of argon and dry air. The effect of substrate roughness and working pressure on the physical properties and the photocatalytic properties of the N-doped TiO x films was investigated. The surface roughness of glass substrate has little influence on the film properties such as produced phases, lattice parameters, introduced nitrogen contents, and atomic bonding configurations, but significant influence on the surface roughness of film resulting in the variation of the photocatalytic ability. The working pressure has little influence on the produced phases and the atomic bonding configurations, but significant influence on the atomic concentration of the N-doped TiO x film, resulting in the large variation of optical, structural, and photocatalytic properties. It is suggested that the high photocatalysis of N-doped TiO x film requires a certain range of the N doping concentration which shows the interstitial complex N doping states in TiO 2
Magnetic engineering in InSe/black-phosphorus heterostructure by transition-metal-atom Sc-Zn doping in the van der Waals gap

Science.gov (United States)

Ding, Yi-min; Shi, Jun-jie; Zhang, Min; Zhu, Yao-hui; Wu, Meng; Wang, Hui; Cen, Yu-lang; Guo, Wen-hui; Pan, Shu-hang

2018-07-01

Within the framework of the spin-polarized density-functional theory, we have studied the electronic and magnetic properties of InSe/black-phosphorus (BP) heterostructure doped with 3d transition-metal (TM) atoms from Sc to Zn. The calculated binding energies show that TM-atom doping in the van der Waals (vdW) gap of InSe/BP heterostructure is energetically favorable. Our results indicate that magnetic moments are induced in the Sc-, Ti-, V-, Cr-, Mn- and Co-doped InSe/BP heterostructures due to the existence of non-bonding 3d electrons. The Ni-, Cu- and Zn-doped InSe/BP heterostructures still show nonmagnetic semiconductor characteristics. Furthermore, in the Fe-doped InSe/BP heterostructure, the half-metal property is found and a high spin polarization of 100% at the Fermi level is achieved. The Cr-doped InSe/BP has the largest magnetic moment of 4.9 μB. The Sc-, Ti-, V-, Cr- and Mn-doped InSe/BP heterostructures exhibit antiferromagnetic ground state. Moreover, the Fe- and Co-doped systems display a weak ferromagnetic and paramagnetic coupling, respectively. Our studies demonstrate that the TM doping in the vdW gap of InSe/BP heterostructure is an effective way to modify its electronic and magnetic properties.
A first-principles study of structure, orbital interactions and atomic oxygen and OH adsorption on Mo-, Sc- and Y-doped nickel bimetallic clusters

International Nuclear Information System (INIS)

Das, Nishith Kumar; Shoji, Tetsuo

2013-01-01

Highlights: •Mo-doped nickel clusters are energetically more stable than the Sc and Y-doped clusters (n ⩾ 10). •Mo atom exhibits center at the cluster rather than edge, while Sc and Y atom sit at the edge. •The metallic s, d orbitals are mainly dominated on the stability of nanoclusters. •The oxygen and OH adsorption energy of Mo-doped cluster are higher than those of other nanoclusters. •2p Orbitals are strongly bonds with Mo 4d, and a weakly interacts with Ni 3d, 4s and Mo 5s orbitals. -- Abstract: Density functional theory (DFT) has been used to study the stability, orbitals interactions and oxygen and hydroxyl chemisorption properties of Ni n M (1 ⩽ n ⩽ 12) clusters. A single atom doped-nickel clusters increase the stability, and icosahedral Ni 12 Mo cluster is the most stable structure. Molybdenum atom prefers to exhibit center at the cluster (n ⩾ 10) rather than edge, while Sc and Y atom remain at the edge. The Ni–Mo bond lengths are smaller than the Ni–Sc and Ni–Y. The pDOS results show that the d–d orbitals interactions are mainly dominating on the stability of clusters, while p orbitals have a small effect on the stability. The Mo-doped nanoclusters have the highest oxygen and OH chemisorption energy, and the most favorable adsorption site is on the top Mo site. The larger cluster distortion is found for the Sc- and Y-doped structures compared to other clusters. The oxygen 2p orbitals are strongly hybridizing with the Mo 4d orbitals (n < 9) and a little interaction between oxygen 2p and Ni 3d, 4s and Mo 5s orbitals. The Mo-doped clusters are significantly increased the chemisorption energies that might improve the passive film adherence of nanoalloys
Hollow Amorphous MnSnO3 Nanohybrid with Nitrogen-Doped Graphene for High-Performance Lithium Storage

International Nuclear Information System (INIS)

Liu, Peng; Hao, Qingli; Xia, Xifeng; Lei, Wu; Xia, Hui; Chen, Ziyang; Wang, Xin

2016-01-01

Graphical abstract: A novel hybrid of hollow amorphous MnSnO 3 nanoparticles and nitrogen-doped reduced graphene oxide was fabricated. The unique structure and well-combination of both components account for the ultra long-term cyclic life with high reversible capacity of 610 mAh g −1 over 1000 cycles at 400 mA g −1 . - Highlights: • Novel hybrid of MnSnO 3 and nitrogen-doped reduced graphene oxide was fabricated. • The MnSnO 3 nanoparticles possess amorphous and hollow structure in the composite. • The excellent electrochemical performance benefits from unique nanostructure. • The reversible capacity of as-prepared hybrid is 610 mAh g −1 after 1000 cycles. • A long-term life with 97.3% capacity retention over 1000 cycles was obtained. - Abstract: Tin-based metal oxides usually suffer from severe capacity fading resulting from aggregation and considerable volume variation during the charge/discharge process in lithium ion batteries. In this work, a novel nanocomposite (MTO/N-RGO) of hollow amorphous MnSnO 3 (MTO) nanoparticles and nitrogen-doped reduced graphene oxide (N-RGO) has been designed and synthesized by a two-step method. Firstly, the nitrogen-doped graphene nanocomposite (MTO/N-RGO-P) with MnSn(OH) 6 crystal nanoparticles was synthesized by a facile solvothermal method. Subsequently, the MTO/N-RGO nanocomposite was obtained through the post heat treatment of MTO/N-RGO-P. The designed heterostructure and well-combination of the hollow amorphous MTO and N-RGO matrix can accelerate the ionic and electronic transport, and simultaneously accommodate the aggregation and volume variation of MTO nanoparticles during the lithiation–delithiation cycles. The as-prepared hybrid of MTO and N-RGO (MTO/N-RGO) exhibits a high reversible capacity of 707 mAh g −1 after 110 cycles at 200 mA g −1 , superior rate capability, and long-term cyclic life with high capacity of 610 mAh g −1 over 1000 cycles at 400 mA g −1 . Superior capacity retention of
Reactive template synthesis of nitrogen-doped graphene-like carbon nanosheets derived from hydroxypropyl methylcellulose and dicyandiamide as efficient oxygen reduction electrocatalysts

Science.gov (United States)

Hu, Chun; Zhou, Yao; Ma, Ruguang; Liu, Qian; Wang, Jiacheng

2017-03-01

Oxygen reduction reaction (ORR) plays a dominant role in proton exchange membrane fuel cells (PEMFCs). Thus, the design and preparation of efficient ORR electrocatalysts is of high importance. In this work, we successfully prepared a series of nitrogen-doped graphene-like carbon nanosheets (NCNSs) with large pore volumes of up to 1.244 cm3 g-1 and high level of N dopants (5.3-6.8 at%) via a one-step, in-situ reactive template strategy by co-pyrolysis of hydroxypropyl methylcellulose (HPMC) and dicyandiamide (DICY) as the precursors at 1000 °C. The DICY-derived graphitic carbon nitride (g-C3N4) nanosheets could act as the hard template for the confined growth of 2D carbon nanosheets, and the further increase in the pyrolysis temperature could directly remove off the g-C3N4 template by complete decomposition and simultaneously dope N atoms within the carbon nanosheets. The pyridinic and graphitic nitrogen groups are dominant among various N functional groups in the NCNSs. The NCNS_1:10 prepared with the HPMC/DICY mass ratio of 1/10 can be used as the metal-free ORR electrocatalysts with optimal activity (onset potential: -0.1 V vs. SCE; limiting current density: 4.8 mA cm-2) in O2-saturated 0.1 M KOH electrolyte among the NCNSs. Moreover, the NCNS_1:10 demonstrates a dominant four-electron reduction process, as well as excellent long-term operation stability and outstanding methanol crossover resistance. The excellent ORR activity of the NCNS_1:10 should be mainly owing to high contents of pyridinic and graphitic N dopants, large pore volume, hierarchical structures, and microstructural defects.
Ab Initio Assessment of the Bonding in Disulfonates Containing Divalent Nitrogen and Phosphorus Atoms

DEFF Research Database (Denmark)

Andersen, Vinca Bonde; Berg, Rolf W.; Shim, Irene

2017-01-01

The iminodisulfonate, [N(SO3)2]3–, and phosphinodisulfonate, [P(SO3)2]3–, ions have been investigated by performing ab initio MP2/6-311+G**calculations. The nitrogen and phosphorus atoms as part of the ions are shown to be divalent with a negative charge and two lone pairs on the nitrogen...
Highly concentrated, stable nitrogen-doped graphene for supercapacitors: Simultaneous doping and reduction

Energy Technology Data Exchange (ETDEWEB)

Jiang Baojiang [College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin (China); Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education of the People' s Republic of China, Heilongjiang University, Harbin (China); Tian Chungui; Wang Lei; Sun Li; Chen Chen; Nong Xiaozhen [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education of the People' s Republic of China, Heilongjiang University, Harbin (China); Qiao Yingjie, E-mail: qiaoyingjie@hrbeu.edu.cn [College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin (China); Fu Honggang, E-mail: fuhg@vip.sina.com [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education of the People' s Republic of China, Heilongjiang University, Harbin (China)

2012-02-01

In this work, we developed a concentrated ammonia-assisted hydrothermal method to obtain N-doped graphene sheets by simultaneous N-doping and reduction of graphene oxide (GO) sheets. The effects of hydrothermal temperature on the surface chemistry and the structure of N-doped graphene sheets were also investigated. X-ray photoelectron spectroscopy (XPS) study of N-doped graphene reveals that the highest doping level of 7.2% N is achieved at 180 Degree-Sign C for 12 h. N binding configurations of sample consist of pyridine N, quaternary N, and pyridine-N oxides. N doping is accompanied by the reduction of GO with decreases in oxygen levels from 34.8% in GO down to 8.5% in that of N-doped graphene. Meanwhile, the sample exhibits excellent N-doped thermal stability. Electrical measurements demonstrate that products have higher capacitive performance than that of pure graphene, the maximum specific capacitance of 144.6 F/g can be obtained which ascribe the pseudocapacitive effect from the N-doping. The samples also show excellent long-term cycle stability of capacitive performance.
Highly concentrated, stable nitrogen-doped graphene for supercapacitors: Simultaneous doping and reduction

Science.gov (United States)

Jiang, Baojiang; Tian, Chungui; Wang, Lei; Sun, Li; Chen, Chen; Nong, Xiaozhen; Qiao, Yingjie; Fu, Honggang

2012-02-01

In this work, we developed a concentrated ammonia-assisted hydrothermal method to obtain N-doped graphene sheets by simultaneous N-doping and reduction of graphene oxide (GO) sheets. The effects of hydrothermal temperature on the surface chemistry and the structure of N-doped graphene sheets were also investigated. X-ray photoelectron spectroscopy (XPS) study of N-doped graphene reveals that the highest doping level of 7.2% N is achieved at 180 °C for 12 h. N binding configurations of sample consist of pyridine N, quaternary N, and pyridine-N oxides. N doping is accompanied by the reduction of GO with decreases in oxygen levels from 34.8% in GO down to 8.5% in that of N-doped graphene. Meanwhile, the sample exhibits excellent N-doped thermal stability. Electrical measurements demonstrate that products have higher capacitive performance than that of pure graphene, the maximum specific capacitance of 144.6 F/g can be obtained which ascribe the pseudocapacitive effect from the N-doping. The samples also show excellent long-term cycle stability of capacitive performance.
Magnetic properties of Mg{sub 12}O{sub 12} nanocage doped with transition metal atoms (Mn, Fe, Co and Ni): DFT study

Energy Technology Data Exchange (ETDEWEB)

Javan, Masoud Bezi, E-mail: javan.masood@gmail.com

2015-07-01

Binding energy of the Mg{sub 12}O{sub 12} nanocage doped with transition metals (TM=Mn, Fe, Co and Ni) in endohedrally, exohedrally and substitutionally forms were studied using density functional theory with the generalized gradient approximation exchange-correlation functional along 6 different paths inside and outside of the Mg{sub 12}O{sub 12} nanocage. The most stable structures were determined with full geometry optimization near the minimum of the binding energy curves of all the examined paths inside and outside of the Mg{sub 12}O{sub 12} nanocage. The results reveal that for all stable structures, the Ni atom has a larger binding energy than the other TM atoms. It is also found that for all complexes additional peaks contributed by TM-3d, 4s and 4p states appear in the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) gap of the host MgO cluster. The mid-gap states are mainly due to the hybridization between TM-3d, 4s and 4p orbitals and the cage π orbitals. The magnetic moment of the endohedrally doped TM atoms in the Mg{sub 12}O{sub 12} are preserved to some extent due to the interaction between the TM and Mg{sub 12}O{sub 12} nanocage, in contrast to the completely quenched magnetic moment of the Fe and Ni atoms in the Mg{sub 11}(TM)O{sub 12} complexes. Furthermore, charge population analysis shows that charge transfer occurs from TM atom to the cage for endohedrally and substitutionally doping. - Highlights: • Binding energy of the Mg{sub 12}O{sub 12} nanocage doped with transition metals was studied. • The most stable structures were determined near the minimum of the binding energy. • The encapsulated Ni atom has a larger binding energy than the other TM atoms. • Magnetic moment of the endohedrally doped TM atoms in the Mg{sub 12}O{sub 12} are preserved.
Electrocatalytic activity of atomic layer deposited Pt-Ru catalysts onto N-doped carbon nanotubes

NARCIS (Netherlands)

Johansson, A.-C.; Larsen, J.V.; Verheijen, M.A.; Haugshøj, K.B.; Clausen, H.; Kessels, W.M.M.; Christensen, L.H.; Thomsen, E.V.

2014-01-01

Pt-Ru catalysts of various compositions, between 0 and 100 at.% of Ru, were deposited onto N-doped multi-walled carbon nanotubes (N-CNTs) by atomic layer deposition (ALD) at 250 C. The Pt and Ru precursors were trimethyl(methylcyclopentadienyl)platinum (MeCpPtMe3) and
Properties of Nitrogen-Doped Zinc Telluride Films for Back Contact to Cadmium Telluride Photovoltaics

Science.gov (United States)

Shimpi, Tushar M.; Drayton, Jennifer; Swanson, Drew E.; Sampath, Walajabad S.

2017-08-01

Zinc telluride (ZnTe) films have been deposited onto uncoated glass superstrates by reactive radiofrequency (RF) sputtering with different amounts of nitrogen introduced into the process gas, and the structural and electronic transport properties of the resulting nitrogen-doped ZnTe (ZnTe:N) films characterized. Based on transmission and x-ray diffraction measurements, it was observed that the crystalline quality of the ZnTe:N films decreased with increasing nitrogen in the deposition process. The bulk carrier concentration of the ZnTe:N films determined from Hall-effect measurements showed a slight decrease at 4% nitrogen flow rate. The effect of ZnTe:N films as back contact to cadmium telluride (CdTe) solar cells was also investigated. ZnTe:N films were deposited before or after CdCl2 passivation on CdTe/CdS samples. Small-area devices were characterized for their electronic properties. Glancing-angle x-ray diffraction measurements and energy-dispersive spectroscopy analysis confirmed substantial loss of zinc from the samples where CdCl2 passivation was carried out after ZnTe:N film deposition.
Determination of the nitrogen vacancy as a shallow compensating center in GaN doped with divalent metals.

Science.gov (United States)

Buckeridge, J; Catlow, C R A; Scanlon, D O; Keal, T W; Sherwood, P; Miskufova, M; Walsh, A; Woodley, S M; Sokol, A A

2015-01-09

We report accurate energetics of defects introduced in GaN on doping with divalent metals, focusing on the technologically important case of Mg doping, using a model that takes into consideration both the effect of hole localization and dipolar polarization of the host material, and includes a well-defined reference level. Defect formation and ionization energies show that divalent dopants are counterbalanced in GaN by nitrogen vacancies and not by holes, which explains both the difficulty in achieving p-type conductivity in GaN and the associated major spectroscopic features, including the ubiquitous 3.46 eV photoluminescence line, a characteristic of all lightly divalent-metal-doped GaN materials that has also been shown to occur in pure GaN samples. Our results give a comprehensive explanation for the observed behavior of GaN doped with low concentrations of divalent metals in good agreement with relevant experiment.
Determination of the Nitrogen Vacancy as a Shallow Compensating Center in GaN Doped with Divalent Metals

Science.gov (United States)

Buckeridge, J.; Catlow, C. R. A.; Scanlon, D. O.; Keal, T. W.; Sherwood, P.; Miskufova, M.; Walsh, A.; Woodley, S. M.; Sokol, A. A.

2015-01-01

We report accurate energetics of defects introduced in GaN on doping with divalent metals, focusing on the technologically important case of Mg doping, using a model that takes into consideration both the effect of hole localization and dipolar polarization of the host material, and includes a well-defined reference level. Defect formation and ionization energies show that divalent dopants are counterbalanced in GaN by nitrogen vacancies and not by holes, which explains both the difficulty in achieving p -type conductivity in GaN and the associated major spectroscopic features, including the ubiquitous 3.46 eV photoluminescence line, a characteristic of all lightly divalent-metal-doped GaN materials that has also been shown to occur in pure GaN samples. Our results give a comprehensive explanation for the observed behavior of GaN doped with low concentrations of divalent metals in good agreement with relevant experiment.
Superior supercapacitors based on nitrogen and sulfur co-doped hierarchical porous carbon: Excellent rate capability and cycle stability

Science.gov (United States)

Zhang, Deyi; Han, Mei; Wang, Bing; Li, Yubing; Lei, Longyan; Wang, Kunjie; Wang, Yi; Zhang, Liang; Feng, Huixia

2017-08-01

Vastly improving the charge storage capability of supercapacitors without sacrificing their high power density and cycle performance would bring bright application prospect. Herein, we report a nitrogen and sulfur co-doped hierarchical porous carbon (NSHPC) with very superior capacitance performance fabricated by KOH activation of nitrogen and sulfur co-doped ordered mesoporous carbon (NSOMC). A high electrochemical double-layer (EDL) capacitance of 351 F g-1 was observed for the reported NSHPC electrodes, and the capacitance remains at 288 F g-1 even under a large current density of 20 A g-1. Besides the high specific capacitance and outstanding rate capability, symmetrical supercapacitor cell based on the NSHPC electrodes also exhibits an excellent cycling performance with 95.61% capacitance retention after 5000 times charge/discharge cycles. The large surface area caused by KOH activation (2056 m2 g-1) and high utilized surface area owing to the ideal micro/mesopores ratio (2.88), large micropores diameter (1.38 nm) and short opened micropores structure as well as the enhanced surface wettability induced by N and S heteroatoms doping and improved conductivity induced by KOH activation was found to be responsible for the very superior capacitance performance.
Enhanced non-enzymatic glucose sensing based on copper nanoparticles decorated nitrogen-doped graphene.

Science.gov (United States)

Jiang, Ding; Liu, Qian; Wang, Kun; Qian, Jing; Dong, Xiaoya; Yang, Zhenting; Du, Xiaojiao; Qiu, Baijing

2014-04-15

Copper nanoparticles (NPs) decorated nitrogen-doped graphene (Cu-N-G) was prepared by a facile thermal treatment, and further employed as a novel sensing material for fabricating the sensitive non-enzymatic glucose sensor. Compared with pure Cu NPs, the Cu-N-G showed enhanced electrocatalytic activity to glucose oxidation due to the integration of N-G, which exhibited the oxidation peak current of glucose ca. 23-fold higher than that of pure Cu NPs. The presented sensor showed excellent performances for glucose detection including wide linear range of 0.004-4.5 mM, low detection limit (1.3 μM, S/N=3), high sensitivity (48.13 μA mM(-1)), fast response time (doped graphene as enhanced materials in fabricating sensors for chemical and biochemical analysis. © 2013 Published by Elsevier B.V.
Adsorption of hydrogen in Scandium/Titanium decorated nitrogen doped carbon nanotube

Energy Technology Data Exchange (ETDEWEB)

Mananghaya, Michael, E-mail: mikemananghaya@gmail.com [De La Salle University, 2401 Taft Ave, 0922, Manila (Philippines); DLSU STC Laguna Boulevard, LTI Spine Road Barangays Biñan and Malamig, Biñan City, Laguna (Philippines); DOST-ASTHRDP, PCIEERD, Gen. Santos Ave., Bicutan, Taguig City 1631 (Philippines); Belo, Lawrence Phoa; Beltran, Arnel [De La Salle University, 2401 Taft Ave, 0922, Manila (Philippines); DLSU STC Laguna Boulevard, LTI Spine Road Barangays Biñan and Malamig, Biñan City, Laguna (Philippines)

2016-09-01

Nitrogen doped Carbon Nanotube with divacancy (4ND-CN{sub x}NT) that is decorated with Scandium and Titanium as potential hydrogen storage medium using the pseudo potential density functional method was investigated. Highly localized states near the Fermi level, which are derived from the nitrogen defects, contribute to strong Sc and Ti bindings, which prevent metal aggregation and improve the material stability. A detailed Comparison of the Hydrogen adsorption capability with promising system-weight efficiency of Sc over Ti was elucidated when functionalized with 4ND-CN{sub x}NT. Finally, the (Sc/4ND){sub 10}-CN{sub x}CNT composite material has a thermodynamically favorable adsorption and consecutive adsorption energy for ideal reversible adsorption and desorption of hydrogen at room temperature such that it can hold at least 5.8 wt% hydrogen molecules at the LDA and GGA level. - Highlights: • Carbon Nanotube with divacancy (4ND-CN{sub x}NT) decorated with Sc and Ti. • Nitrogen defects, contribute to strong Sc and Ti bindings. • H{sub 2} and (Sc/4ND){sub 10}-CN{sub x}CNT has a favorable adsorption. • 5.8 wt% adsorption at the LDA and GGA level.
Three-dimensional nitrogen and boron co-doped graphene for high-performance all-solid-state supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Wu, Zhong-Shuai; Chen, Long; Sun, Yi; Muellen, Klaus [Max-Planck-Institut fuer Polymerforschung, Ackermannweg 10, 55128 Mainz (Germany); Winter, Andreas; Turchanin, Andrey [Universitaet Bielefeld, Fakultaet fuer Physik, Physik Supramolekularer Systeme und Oberflaechen, Universitaetsstr. 25D, 33615 Bielefeld (Germany); Feng, Xinliang [Max-Planck-Institut fuer Polymerforschung, Ackermannweg 10, 55128 Mainz (Germany); School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 200240, Shanghai (China)

2012-09-25

A simplified prototype device of high-performance all-solid-state supercapacitors (ASSSs) based on 3D nitrogen and boron co-doped monolithic graphene aerogels (BN-GAs) is demonstrated for the first time. The resulting ASSSs show high specific capacitance, good rate capability, and enhanced energy density or power density. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
N-doped Sb2Te phase change materials for higher data retention

International Nuclear Information System (INIS)

Zhu Min; Wu Liangcai; Rao Feng; Song Zhitang; Li Xuelai; Peng Cheng; Zhou Xilin; Ren Kun; Yao Dongning; Feng Songlin

2011-01-01

Highlights: → Crystallization temperatures of the N-doped Sb 2 Te films increase remarkably. → The E a of N-doped Sb 2 Te films increase first, and then decrease. → The best 10-years lifetime at temperature up to 141 deg. C is found in Sb 2 TeN1 films. → The power consumption of PCRAM test cell based on Sb 2 TeN1 film is low. - Abstract: Crystallization temperatures of the Sb 2 Te films increase remarkably from 139.4 deg. C to 223.0 deg. C as the N 2 flow rates increasing from 0 sccm to 1.5 sccm. Electrical conduction activation energies for amorphous and crystalline states increase by doping nitrogen. A small amount of nitrogen atoms can locate at interstitial sites in the hexagonal structure, generating a strain field, and improving the thermal stability of amorphous state. The best 10-years lifetime at temperature up to 141 deg. C is found in Sb 2 TeN 1 films. Doping excessively high nitrogen in Sb 2 Te film will form nitride and make Te separate out. As a result, the activation energy for crystallization decreases instead, accompanying with the deterioration of thermal stability. The power consumption of PCRAM test cell based on Sb 2 TeN 1 film is ten times lower than that of PCRAM device using Ge 2 Sb 2 Te 5 films.

Nitrogen-doped hierarchical porous carbon materials prepared from meta-aminophenol formaldehyde resin for supercapacitor with high rate performance

International Nuclear Information System (INIS)

Zhou, Jin; Zhang, Zhongshen; Xing, Wei; Yu, Jing; Han, Guoxing; Si, Weijiang; Zhuo, Shuping

2015-01-01

Graphical abstract: N-doped hierarchical porous carbons with high rate capacitive performance are prepared by a combination method of nano-SiO 2 template/KOH activation. - Highlights: • A mass produced nano-SiO 2 is used to prepared hierarchical porous carbon. • N-doped hierarchical porous carbon materials are easily prepared. • The NHPCs materials exhibit a very high capacitance of up to 260.5 F g −1 . • The NHPC-800 sample shows very high rate capability. • Hierarchical porosity and N-doping synergistically enhances the whole capacitance. - Abstract: In this work, nitrogen-doped hierarchical porous carbon materials (NHPCs) are prepared by a two-step method combined of a hard template process and KOH-activation treatment. Low cost and large-scale commercial nano-SiO 2 are used as a hard template. The hierarchical porosity, structure and nitrogen-doped surface chemical properties are proved by a varies of means, such as scanning electron microscopy, transition electron microscopy, N 2 sorption, Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. When the prepared NHPCs materials are used as the electrode materials for supercapacitors in KOH electrolyte, they exhibit very high specific capacitance, good power capability and excellent cyclic stability. NHPC-800 carbon shows a high capacitance of 114.0 F g −1 at the current density of 40 A g −1 , responding to a high energy and power densities of 4.0 Wh kg −1 and 10 000 W kg −1 , and a very short drain time of 1.4 s. The excellent capacitive performance may be due to the synergistic effect of the hierarchical porosity, high effective surface area and heteroatom doping, resulting in both electrochemical double layer and Faradaic capacitance contributions
Nitrogen-doped porous carbons for highly selective CO2 capture from flue gases and natural gas upgrading

NARCIS (Netherlands)

Wang, J.; Krishna, R.; Yang, J.; Dandamudi, K.P.R.; Deng, S.

2015-01-01

Nitrogen-doped microporous activated carbon adsorbents were synthesized by a self-template method with KOH as the porogen agent at pyrolysis temperatures of 600, 700, and 800 degrees C. The carbon adsorbent samples were characterized with N-2 adsorption at 77 K, X-ray diffraction, scanning electron
Metal-Organic-Framework-Mediated Nitrogen-Doped Carbon for CO2 Electrochemical Reduction

KAUST Repository

Wang, Riming; Sun, Xiaohui; Ould-Chikh, Samy; Osadchii, Dmitrii; Bai, Fan; Kapteijn, Freek; Gascon, Jorge

2018-01-01

A nitrogen-doped carbon was synthesized through the pyrolysis of the well-known metal-organic framework ZIF-8, followed by a subsequent acid treatment, and has been applied as a catalyst in the electrochemical reduction of carbon dioxide. The resulting electrode shows Faradaic efficiencies to carbon monoxide as high as ∼78%, with hydrogen being the only byproduct. The pyrolysis temperature determines the amount and the accessibility of N species in the carbon electrode, in which pyridinic-N and quaternary-N species play key roles in the selective formation of carbon monoxide.
Metal-Organic-Framework-Mediated Nitrogen-Doped Carbon for CO2 Electrochemical Reduction

KAUST Repository

Wang, Riming

2018-04-11

A nitrogen-doped carbon was synthesized through the pyrolysis of the well-known metal-organic framework ZIF-8, followed by a subsequent acid treatment, and has been applied as a catalyst in the electrochemical reduction of carbon dioxide. The resulting electrode shows Faradaic efficiencies to carbon monoxide as high as ∼78%, with hydrogen being the only byproduct. The pyrolysis temperature determines the amount and the accessibility of N species in the carbon electrode, in which pyridinic-N and quaternary-N species play key roles in the selective formation of carbon monoxide.
Alteration of the soliton behavior in silica-fibers doped with passive resonant atoms

International Nuclear Information System (INIS)

Torres-Cisneros, G. E.; Nabiev, R.F.

1991-01-01

We have numerically studied for the first time the full dynamics describing the pulse propagation phenomenon in single-mode-silica-fibers doped with passive resonant two level atoms. For the specific case of a 3-order soliton we show that the inclusion of the resonant nonlinearities destroys the fundamental characteristics of the pulse soliton behavior. (Author)
Nitrogen-doped biomass-based ultra-thin carbon nanosheets with interconnected framework for High-Performance Lithium-Ion Batteries

Science.gov (United States)

Guo, Shasha; Chen, Yaxin; Shi, Liluo; Dong, Yue; Ma, Jing; Chen, Xiaohong; Song, Huaihe

2018-04-01

In this paper, a low-cost and environmental friendly synthesis strategy is proposed to fabricate nitrogen-doped biomass-based ultra-thin carbon nanosheets (N-CNS) with interconnected framework by using soybean milk as the carbon precursor and sodium chloride as the template. The interconnected porous nanosheet structure is beneficial for lithium ion transportation, and the defects introduced by pyridine nitrogen doping are favorable for lithium storage. When used as the anodes for lithium-ion batteries, the N-CNS electrode shows a high initial reversible specific capacity of 1334 mAh g-1 at 50 mA g-1, excellent rate performance (1212, 555 and 336 mAh g-1 at 0.05, 0.5 and 2 A g-1, respectively) and good cycling stability (355 mAh g-1 at 1 A g-1 after 1000 cycles). Furthermore, this study demonstrates the prospects of biomass and soybean milk, as the potential anode for the application of electrochemical energy storage devices.
Synthesis of nitrogen doped microporous carbons prepared by activation-free method and their high electrochemical performance

Energy Technology Data Exchange (ETDEWEB)

Kim, Ki-Seok [Department of Chemistry, Inha University, Incheon 402-751 (Korea, Republic of); Park, Soo-Jin, E-mail: sjpark@inha.ac.kr [Department of Chemistry, Inha University, Incheon 402-751 (Korea, Republic of)

2011-11-30

Graphical abstract: This describes the increase of specific capacitance in hybrid electrodes as a function of melamine content. Display Omitted Highlights: > For N-enriched hybrid carbons, co-precursors, PVDF/melamine composites, were used. > Microporous carbons were formed by only carbonization without chemical activation. > The nitrogen content of microporous carbons was controlled by melamine content. > N-doped carbons showed higher specific capacitance compared to microporous carbons. > It was attributed to the easy electron transfer and pseudocapacitance. - Abstract: Nitrogen-doped microporous carbons (N-MCs) were prepared by the carbonization of the polyvinylidene fluoride (PVDF)/melamine mixture without chemical activation. The electrochemical performance of the N-MCs was investigated as a function of PVDF/melamine ratio. It was found that, without additional activation, the N-MCs had a high specific surface area (greater than 560 m{sup 2}/g) because of the micropore formation by the release of fluorine groups. In addition, although the specific surface area decreased, nitrogen groups were increased with increasing melamine content, leading to an enhanced electrochemical performance. Indeed, the N-MCs showed a better electrochemical performance than that of microporous carbons (MCs) prepared by PVDF alone, and the highest specific capacitance (310 F/g) was obtained at a current density of 0.5 A/g, as compared to a value of 248 F/g for MCs. These results indicate that the microporous features of N-MC lead to feasible ion transfer during charge/discharge duration and the presence of nitrogen groups as strong electron donor on the N-MC electrode in electrolyte could provide a pseudocapacitance by the redox reaction.
Unravelling the interplay of geometrical, magnetic and electronic properties of metal-doped graphene nanomeshes

KAUST Repository

Fadlallah, Mohamed M.

2016-12-02

Graphene nanomeshes (GNMs), formed by creating a superlattice of pores in graphene, possess rich physical and chemical properties. Many of these properties are determined by the pore geometry. In this work, we use first principles calculations to study the magnetic and electronic properties of metal-doped nitrogen-passivated GNMs. We find that the magnetic behaviour is dependent on the pore shape (trigonal versus hexagonal) as dictated by the number of covalent bonds formed between the 3d metal and the passivating N atoms. We also find that Cr and V doped trigonal-pore GNMs, and Ti doped GNMs are the most favourable for spintronic applications. The calculated magnetic properties of Fe-doped GNMs compare well with recent experimental observations. The studied systems are useful as spin filters and chemical sensors.
Effect of B, N, Ge, Sn, K doping on electronic-transport properties of (5, 0) zigzag carbon nanotube

Science.gov (United States)

Kamalian, Monir; Seyed Jalili, Yousef; Abbasi, Afshin

2018-04-01

In this paper the effect of impurity on the electronic properties and quantum conductance of zigzag (5, 0) carbon nanotube have been studied by using the Density Functional Theory (DFT) combined with Non-Equilibrium Green’s Function (NEGF) formalism with TranSIESTA software. The effect of Boron (B), Nitrogen (N), Germanium (Ge), Tin (Sn) and Potassium (K) impurities on the CNT conduction behavior and physical characteristics, like density of states (DOS), band structure, transmission coefficients and quantum conductance was considered and discussed simultaneously. The current‑voltage (I‑V) curves of all the proposed models were studied for comparative study under low-bias conditions. The distinct changes in conductance reported as the positions, number and type of dopants was varied in central region of the CNT between two electrodes at different bias voltages. This suggested conductance enhancement mechanism for the charge transport in the doped CNT at different positions is important for the design of CNT based nanoelectronic devices. The results show that Germanium, Tin and Potassium dopant atoms has increased the conductance of the model manifold than other doping atoms furthermore 10 Boron and 10 Nitrogen dopant atoms showed the amazing property of Negative Differential Resistance (NDR).
Nitrogen-Doped Carbon Encapsulated Nickel/Cobalt Nanoparticle Catalysts for Olefin Migration of Allylarenes

DEFF Research Database (Denmark)

Kramer, Søren; Mielby, Jerrik Jørgen; Buss, Kasper Spanggård

2017-01-01

Olefin migration of allylarenes is typically performed with precious metal-based homogeneous catalysts. In contrast, very limited progress has been made using cheap, earth-abundant base metals as heterogeneous catalysts for these transformations - in spite of the obvious economic and environmental...... advantages. Herein, we report on the use of an easily prepared heterogeneous catalyst material for the migration of olefins, in particular allylarenes. The catalyst material consists of nickel/cobalt alloy nanoparticles encapsulated in nitrogen-doped carbon shells. The encapsulated nanoparticles are stable...
Atomic scale insight into the amorphous structure of Cu doped GeTe phase-change material

International Nuclear Information System (INIS)

Zhang, Linchuan; Sa, Baisheng; Zhou, Jian; Sun, Zhimei; Song, Zhitang

2014-01-01

GeTe shows promising application as a recording material for phase-change nonvolatile memory due to its fast crystallization speed and extraordinary amorphous stability. To further improve the performance of GeTe, various transition metals, such as copper, have been doped in GeTe in recent works. However, the effect of the doped transition metals on the stability of amorphous GeTe is not known. Here, we shed light on this problem for the system of Cu doped GeTe by means of ab initio molecular dynamics calculations. Our results show that the doped Cu atoms tend to agglomerate in amorphous GeTe. Further, base on analyzing the pair correlation functions, coordination numbers and bond angle distributions, remarkable changes in the local structure of amorphous GeTe induced by Cu are obviously seen. The present work may provide some clues for understanding the effect of early transition metals on the local structure of amorphous phase-change compounds, and hence should be helpful for optimizing the structure and performance of phase-change materials by doping transition metals.
Electrochemical properties of N-doped hydrogenated amorphous carbon films fabricated by plasma-enhanced chemical vapor deposition methods

Energy Technology Data Exchange (ETDEWEB)

Tanaka, Yoriko; Furuta, Masahiro; Kuriyama, Koichi; Kuwabara, Ryosuke; Katsuki, Yukiko [Division of Environmental Science and Engineering, Graduate School of Science and Engineering, Yamaguchi University, 1677-1 Yoshida, Yamaguchi-shi, Yamaguchi 753-8512 (Japan); Kondo, Takeshi [Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda 278-8510 (Japan); Fujishima, Akira [Kanagawa Advanced Science and Technology (KAST), 3-2-1, Sakato, Takatsu-ku, Kawasaki-shi, Kanagawa 213-0012 (Japan); Honda, Kensuke, E-mail: khonda@yamaguchi-u.ac.j [Division of Environmental Science and Engineering, Graduate School of Science and Engineering, Yamaguchi University, 1677-1 Yoshida, Yamaguchi-shi, Yamaguchi 753-8512 (Japan)

2011-01-01

Nitrogen-doped hydrogenated amorphous carbon thin films (a-C:N:H, N-doped DLC) were synthesized with microwave-assisted plasma-enhanced chemical vapor deposition widely used for DLC coating such as the inner surface of PET bottles. The electrochemical properties of N-doped DLC surfaces that can be useful in the application as an electrochemical sensor were investigated. N-doped DLC was easily fabricated using the vapor of nitrogen contained hydrocarbon as carbon and nitrogen source. A N/C ratio of resulting N-doped DLC films was 0.08 and atomic ratio of sp{sup 3}/sp{sup 2}-bonded carbons was 25/75. The electrical resistivity and optical gap were 0.695 {Omega} cm and 0.38 eV, respectively. N-doped DLC thin film was found to be an ideal polarizable electrode material with physical stability and chemical inertness. The film has a wide working potential range over 3 V, low double-layer capacitance, and high resistance to electrochemically induced corrosion in strong acid media, which were the same level as those for boron-doped diamond (BDD). The charge transfer rates for the inorganic redox species, Fe{sup 2+/3+} and Fe(CN){sub 6}{sup 4-/3-} at N-doped DLC were sufficiently high. The redox reaction of Ce{sup 2+/3+} with standard potential higher than H{sub 2}O/O{sub 2} were observed due to the wider potential window. At N-doped DLC, the change of the kinetics of Fe(CN){sub 6}{sup 3-/4-} by surface oxidation is different from that at BDD. The rate of Fe(CN){sub 6}{sup 3-/4-} was not varied before and after oxidative treatment on N-doped DLC includes sp{sup 2} carbons, which indicates high durability of the electrochemical activity against surface oxidation.
Non-platinum nanocatalyst on porous nitrogen-doped carbon fabricated by cathodic vacuum arc plasma technique

Energy Technology Data Exchange (ETDEWEB)

Sirirak, Reungruthai [Material Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Sarakonsri, Thapanee, E-mail: tsarakonsri@gmail.com [Material Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Medhesuwakul, Min [Plasma & Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

2015-11-30

Highlights: • High surface area porous coral-like nitrogen-doped carbon (NC) and non-platinum nanocatalysts were fabricated on proton exchange membrane using the cathodic vacuum arc plasma (CVAP) technique. • It is a one-step catalysts preparation directly on nafion proton exchange membrane. This CVAP technique is the first new method that was applied in a polymer electrolyte membrane fuel cells (PEMFCs) catalysts preparation. • Due to these excellent characteristics of nitrogen-doped carbon, it is expected to exhibit a good catalyst supporter for PEMFC. • In addition, the Fe–NC catalysts fabricated via this CVAP technique are sphere-like nanoparticle and well disperse on coral-like NC film, which particularity exhibits that these prepared catalysts ought to be a good oxygen reduction reaction (ORR) catalyst for PEMFC. • This approach can be extended to the synthesis of other non-platinum ORR catalyst for broad range applications in energy conversion. - Abstract: Polymer electrolyte membrane fuel cells (PEMFCs) convert chemical energy directly into electrical energy where catalysts composing of non-noble transition metals, nitrogen, and carbon compounds are the most promising materials to replace the expensive platinum catalysts for oxygen reduction reaction (ORR). In this research, cathodic vacuum arc plasma (CVAP) technique was used to fabricate porous nitrogen doped carbon (NC) and non-platinum catalyst on porous NC (Fe–NC) directly on ion exchange membrane for being used as an ORR catalyst at the cathode. The porous NC layer was fabricated on silicon wafer at 0.05 mTorr, 0.1 mTorr, 0.5 mTorr, 1 mTorr, and 5 mTorr of nitrogen gas inlet. The AFM, and SEM images are observed to be regularly big with quite high hillocks and thin NC layers; these results indicate that the optimum process pressure of nitrogen gas inlet is 5 mTorr for porous NC fabrication. The SEM–EDS detects Fe, N, and C elements in the prepared catalysts, and the XRD pattern reviews
Non-platinum nanocatalyst on porous nitrogen-doped carbon fabricated by cathodic vacuum arc plasma technique

International Nuclear Information System (INIS)

Sirirak, Reungruthai; Sarakonsri, Thapanee; Medhesuwakul, Min

2015-01-01

Highlights: • High surface area porous coral-like nitrogen-doped carbon (NC) and non-platinum nanocatalysts were fabricated on proton exchange membrane using the cathodic vacuum arc plasma (CVAP) technique. • It is a one-step catalysts preparation directly on nafion proton exchange membrane. This CVAP technique is the first new method that was applied in a polymer electrolyte membrane fuel cells (PEMFCs) catalysts preparation. • Due to these excellent characteristics of nitrogen-doped carbon, it is expected to exhibit a good catalyst supporter for PEMFC. • In addition, the Fe–NC catalysts fabricated via this CVAP technique are sphere-like nanoparticle and well disperse on coral-like NC film, which particularity exhibits that these prepared catalysts ought to be a good oxygen reduction reaction (ORR) catalyst for PEMFC. • This approach can be extended to the synthesis of other non-platinum ORR catalyst for broad range applications in energy conversion. - Abstract: Polymer electrolyte membrane fuel cells (PEMFCs) convert chemical energy directly into electrical energy where catalysts composing of non-noble transition metals, nitrogen, and carbon compounds are the most promising materials to replace the expensive platinum catalysts for oxygen reduction reaction (ORR). In this research, cathodic vacuum arc plasma (CVAP) technique was used to fabricate porous nitrogen doped carbon (NC) and non-platinum catalyst on porous NC (Fe–NC) directly on ion exchange membrane for being used as an ORR catalyst at the cathode. The porous NC layer was fabricated on silicon wafer at 0.05 mTorr, 0.1 mTorr, 0.5 mTorr, 1 mTorr, and 5 mTorr of nitrogen gas inlet. The AFM, and SEM images are observed to be regularly big with quite high hillocks and thin NC layers; these results indicate that the optimum process pressure of nitrogen gas inlet is 5 mTorr for porous NC fabrication. The SEM–EDS detects Fe, N, and C elements in the prepared catalysts, and the XRD pattern reviews
Enhanced CO2 Adsorption by Nitrogen-Doped Graphene Oxide Sheets (N-GOs Prepared by Employing Polymeric Precursors

Directory of Open Access Journals (Sweden)

Abdulaziz Ali Alghamdi

2018-04-01

Full Text Available Nitrogen-doped graphene oxide sheets (N-GOs are prepared by employing N-containing polymers such as polypyrrole, polyaniline, and copolymer (polypyrrole-polyaniline doped with acids such as HCl, H2SO4, and C6H5-SO3-K, which are activated using different concentrations of KOH and carbonized at 650 °C; characterized using SEM, TEM, BET, TGA-DSC, XRD, and XPS; and employed for the removal of environmental pollutant CO2. The porosity of the N-GOs obtained were found to be in the range 1–3.5 nm when the KOH employed was in the ratio of 1:4, and the XRD confirmed the formation of the layered like structure. However, when the KOH employed was in the ratio of 1:2, the pore diameter was found to be in the range of 50–200 nm. The SEM and TEM analysis reveal the porosity and sheet-like structure of the products obtained. The nitrogen-doped graphene oxide sheets (N-GOs prepared by employing polypyrrole doped with C6H5-SO3-K were found to possess a high surface area of 2870 m2/g. The N-GOs displayed excellent CO2 capture property with the N-GOs; PPy/Ar-1 displayed ~1.36 mmol/g. The precursor employed, the dopant used, and the activation process were found to affect the adsorption property of the N-GOs obtained. The preparation procedure is simple and favourable for the synthesis of N-GOs for their application as adsorbents in greenhouse gas removal and capture.
Study of the metastable singlet of molecular nitrogen and of oxygen atoms in discharges and post-discharges

International Nuclear Information System (INIS)

Magne, Lionel

1991-01-01

Whereas discharges in nitrogen, in oxygen and in their mixtures are used in many different industrial processes (surface treatment, nitridation, oxidation, and so on), in order to get a better knowledge on nitrogen electronic states, this research thesis reports the study of the metastable singlet state of molecular nitrogen, and of oxygen atoms in their fundamental state. The molecular metastable has been observed by far-UV optical emission spectroscopy, in the positive column of a continuous discharge and in time post-discharge. As far as continuous discharge is concerned, the author measured the vibrational distribution of this state. A kinetic model has been developed, and calculated vibrational distributions are in good agreement with measurements. The density of oxygen atoms in fundamental state in time post-discharge has been measured by far-UV absorption optical spectroscopy. The probability of atom re-association of glass walls is deduced from the obtained results [fr
Nitrogen-doped graphene-wrapped iron nanofragments for high-performance oxygen reduction electrocatalysts

Energy Technology Data Exchange (ETDEWEB)

Lee, Jang Yeol [Korea Institute of Science and Technology, Photo-Electronic Hybrid Research Center (Korea, Republic of); Kim, Na Young [Korea Institute of Science and Technology, Fuel Cell Research Center (Korea, Republic of); Shin, Dong Yun [Chungbuk National University, Department of Environmental Engineering (Korea, Republic of); Park, Hee-Young [Korea Institute of Science and Technology, Fuel Cell Research Center (Korea, Republic of); Lee, Sang-Soo [Korea Institute of Science and Technology, Photo-Electronic Hybrid Research Center (Korea, Republic of); Joon Kwon, S. [Korea Institute of Science and Technology, Nanophotonics Research Center (Korea, Republic of); Lim, Dong-Hee [Chungbuk National University, Department of Environmental Engineering (Korea, Republic of); Bong, Ki Wan [Korea University, Department of Chemical and Biological Engineering (Korea, Republic of); Son, Jeong Gon, E-mail: jgson@kist.re.kr [Korea Institute of Science and Technology, Photo-Electronic Hybrid Research Center (Korea, Republic of); Kim, Jin Young, E-mail: jinykim@kist.re.kr [Korea Institute of Science and Technology, Fuel Cell Research Center (Korea, Republic of)

2017-03-15

Transition metals, such as iron (Fe)- or cobalt (Co)-based nanomaterials, are promising electrocatalysts for oxygen reduction reactions (ORR) in fuel cells due to their high theoretical activity and low cost. However, a major challenge to using these metals in place of precious metal catalysts for ORR is their low efficiency and poor stability, thus new concepts and strategies should be needed to address this issue. Here, we report a hybrid aciniform nanostructures of Fe nanofragments embedded in thin nitrogen (N)-doped graphene (Fe@N-G) layers via a heat treatment of graphene oxide-wrapped iron oxide (Fe{sub 2}O{sub 3}) microparticles with melamine. The heat treatment leads to transformation of Fe{sub 2}O{sub 3} microparticles to nanosized zero-valent Fe fragments and formation of core-shell structures of Fe nanofragments and N-doped graphene layers. Thin N-doped graphene layers massively promote electron transfer from the encapsulated metals to the graphene surface, which efficiently optimizes the electronic structure of the graphene surface and thereby triggers ORR activity at the graphene surface. With the synergistic effect arising from the N-doped graphene and Fe nanoparticles with porous aciniform nanostructures, the Fe@N-G hybrid catalyst exhibits high catalytic activity, which was evidenced by high E{sub 1/2} of 0.82 V, onset potential of 0.93 V, and limiting current density of 4.8 mA cm{sup −2} indicating 4-electron ORR, and even exceeds the catalytic stability of the commercial Pt catalyst.
Nitrogen-doped mesoporous carbons for high performance supercapacitors

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Wu, Kai; Liu, Qiming

2016-08-01

The mesoporous carbons have been synthesized by using α-D(+)-Glucose, D-Glucosamine hydrochloride or their mixture as carbon precursors and mesoporous silicas (SBA-15 or MCF) as hard templates. The as-prepared products show a large pore volume (0.59-0.97 cm3 g-1), high surface areas (352.72-1152.67 m2 g-1) and rational nitrogen content (ca. 2.5-3.9 wt.%). The results of electrochemical tests demonstrate that both heteroatom doping and suitable pore structure play a decisive role in the performance of supercapacitors. The representative sample of SBA-15 replica obtained using D-Glucosamine hydrochloride only exhibits high specific capacitance (212.8 F g-1 at 0.5 A g-1) and good cycle durability (86.1% of the initial capacitance after 2000 cycles) in 6 M KOH aqueous electrolyte, which is attributed to the contribution of double layer capacitance and pseudo-capacitance. The excellent electrochemical performance makes it a promising electrode material for supercapacitors.
Porous Hierarchical Nitrogen-doped Carbon Coated ZnFe_2O_4 Composites as High Performance Anode Materials for Lithium Ion Batteries

International Nuclear Information System (INIS)

Yue, Hongyun; Wang, Qiuxian; Shi, Zhenpu; Ma, Chao; Ding, Yanmin; Huo, Ningning; Zhang, Jun; Yang, Shuting

2015-01-01

Porous hierarchical and nitrogen-doped carbon coated ZnFe_2O_4 (ZnFe_2O_4@NC) was obtained by combustion method and unique carbon coating technology. Gum Arabic was firstly introduced in the carbon coating process as an additive, which played an important role to control the uniformity of carbon coating layer. The nitrogen-doped carbon layer was obtained through the pyrolysis of glycine. The elemental composition and content of the nitrogen-doped carbon in composites were characterized by X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS) and thermal gravimetric analysis (TGA). The galvanostatic charge/discharge cycling was used to test the electrochemical performance of ZnFe_2O_4@NC and pure ZnFe_2O_4. The sub-micro size ZnFe_2O_4@NC with unique porous structure showed an excellent electrochemical performance as an anode material, which was higher than that of pure ZnFe_2O_4. ZnFe_2O_4@NC could maintain the specific discharge capacity of 1477 mAh g"−"1 at 0.1 A g"−"1 after 100 cycles and 705 mAh g"−"1 at 1 A g"−"1 after 1000 cycles, respectively.
Indirect electrocatalytic degradation of cyanide at nitrogen-doped carbon nanotube electrodes.

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Wiggins-Camacho, Jaclyn D; Stevenson, Keith J

2011-04-15

Nitrogen-doped carbon nanotube (N-CNT) mat electrodes exhibit high catalytic activity toward O(2) reduction, which can be exploited for the remediation of free cyanide (CN(-)). During the electrochemical O(2) reduction process, the hydroperoxide anion (HO(2)(-)) is formed and then reacts to chemically oxidize cyanide (CN(-)) to form cyanate (OCN(-)). The proposed electrochemical-chemical (EC) mechanism for CN(-) remediation at N-CNTs is supported by cyclic voltammetry and bulk electrolysis, and the formation of OCN(-) is confirmed via spectroscopic methods and electrochemical simulations. Our results indicate that by exploiting their catalytic behavior for O(2) reduction, N-CNTs can efficiently convert toxic CN(-) to the nontoxic OCN(-).

Atomic Iron Catalysis of Polysulfide Conversion in Lithium-Sulfur Batteries.

Science.gov (United States)

Liu, Zhenzhen; Zhou, Lei; Ge, Qi; Chen, Renjie; Ni, Mei; Utetiwabo, Wellars; Zhang, Xiaoling; Yang, Wen

2018-06-13

Lithium-sulfur batteries have been regarded as promising candidates for energy storage because of their high energy density and low cost. It is a main challenge to develop long-term cycling stability battery. Here, a catalytic strategy is presented to accelerate reversible transformation of sulfur and its discharge products in lithium-sulfur batteries. This is achieved with single-atomic iron active sites in porous nitrogen-doped carbon, prepared by polymerizing and carbonizing diphenylamine in the presence of iron phthalocyanine and a hard template. The Fe-PNC/S composite electrode exhibited a high discharge capacity (427 mAh g -1 ) at a 0.1 C rate after 300 cycles with the Columbic efficiency of above 95.6%. Besides, the electrode delivers much higher capacity of 557.4 mAh g -1 at 0.5 C over 300 cycles. Importantly, the Fe-PCN/S has a smaller phase nucleation overpotential of polysulfides than nitrogen-doped carbon alone for the formation of nanoscale of Li 2 S as revealed by ex situ SEM, which enhance lithium-ion diffusion in Li 2 S, and therefore a high rate performance and remarkable cycle life of Li-sulfur batteries were achieved. Our strategy paves a new way for polysulfide conversion with atomic iron catalysis to exploit high-performance lithium-sulfur batteries.
Electrodeposited nitrogen-doped graphene/carbon nanotubes nanocomposite as enhancer for simultaneous and sensitive voltammetric determination of caffeine and vanillin

Energy Technology Data Exchange (ETDEWEB)

Jiang, Lin; Ding, Yaping, E-mail: wdingyp@sina.com; Jiang, Feng; Li, Li; Mo, Fan

2014-06-23

Graphical abstract: A nanocomposite of nitrogen-doped graphene (NGR) and nitrogen-doped carbon nanotubes (NCNTs) was first modified onto an electrode through electrodeposition method and employed to sensitively detect caffeine and vanillin simultaneously for the first time. - Highlights: • The first electrochemical sensor for caffeine (CAF) and vanillin (VAN). • NGR–NCNTs was modified through electrodeposition for the first time. • The sensor was qualified for real sample determination with satisfactory results. - Abstract: A nitrogen-doped graphene/carbon nanotubes (NGR–NCNTs) nanocomposite was employed into the study of the electrochemical sensor via electrodeposition for the first time. The morphology and structure of NGR–NCNTs nanocomposite were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. Meanwhile, the electrochemical performance of the glassy carbon electrode (GCE) modified with electrodeposited NGR–NCNTs (ENGR–NCNTs/GCE) towards caffeine (CAF) and vanillin (VAN) determination was demonstrated by cyclic voltammetry (CV) and square wave voltammetry (SWV). Under optimal condition, ENGR–NCNTs/GCE exhibited a wide linearity of 0.06–50 μM for CAF and 0.01–10 μM for VAN with detection limits of 0.02 μM and 3.3 × 10{sup −3} μM, respectively. Furthermore, the application of the proposed sensor in food products was proven to be practical and reliable. The desirable results show that the ENGR–NCNTs nanocomposite has promising potential in electrocatalytic biosensor application.
Electrodeposited nitrogen-doped graphene/carbon nanotubes nanocomposite as enhancer for simultaneous and sensitive voltammetric determination of caffeine and vanillin

International Nuclear Information System (INIS)

Jiang, Lin; Ding, Yaping; Jiang, Feng; Li, Li; Mo, Fan

2014-01-01

Graphical abstract: A nanocomposite of nitrogen-doped graphene (NGR) and nitrogen-doped carbon nanotubes (NCNTs) was first modified onto an electrode through electrodeposition method and employed to sensitively detect caffeine and vanillin simultaneously for the first time. - Highlights: • The first electrochemical sensor for caffeine (CAF) and vanillin (VAN). • NGR–NCNTs was modified through electrodeposition for the first time. • The sensor was qualified for real sample determination with satisfactory results. - Abstract: A nitrogen-doped graphene/carbon nanotubes (NGR–NCNTs) nanocomposite was employed into the study of the electrochemical sensor via electrodeposition for the first time. The morphology and structure of NGR–NCNTs nanocomposite were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. Meanwhile, the electrochemical performance of the glassy carbon electrode (GCE) modified with electrodeposited NGR–NCNTs (ENGR–NCNTs/GCE) towards caffeine (CAF) and vanillin (VAN) determination was demonstrated by cyclic voltammetry (CV) and square wave voltammetry (SWV). Under optimal condition, ENGR–NCNTs/GCE exhibited a wide linearity of 0.06–50 μM for CAF and 0.01–10 μM for VAN with detection limits of 0.02 μM and 3.3 × 10 −3 μM, respectively. Furthermore, the application of the proposed sensor in food products was proven to be practical and reliable. The desirable results show that the ENGR–NCNTs nanocomposite has promising potential in electrocatalytic biosensor application
Nitrogen and phosphorus co-doped graphene quantum dots: synthesis from adenosine triphosphate, optical properties, and cellular imaging.

Science.gov (United States)

Ananthanarayanan, Arundithi; Wang, Yue; Routh, Parimal; Sk, Mahasin Alam; Than, Aung; Lin, Ming; Zhang, Jie; Chen, Jie; Sun, Handong; Chen, Peng

2015-05-07

Graphene quantum dots (GQDs) are emerging zero-dimensional materials promising a wide spectrum of applications, particularly, as superior fluorescent reporters for bio-imaging and optical sensing. Heteroatom doping can endow GQDs with new or improved photoluminescence properties. Here, we demonstrate a simple strategy for the synthesis of nitrogen and phosphorus co-doped GQDs from a single biomolecule precursor (adenosine triphosphate - ATP). Such ATP-GQDs exhibit high fluorescence quantum yield, strong two-photon upconversion, small molecular weight, high photostability, and good biocompatibility. Furthermore, transferrin conjugated ATP-GQDs have been used for imaging and real-time tracking of transferrin receptors in live cells.
Optical patterning of trapped charge in nitrogen-doped diamond

Science.gov (United States)

Jayakumar, Harishankar; Henshaw, Jacob; Dhomkar, Siddharth; Pagliero, Daniela; Laraoui, Abdelghani; Manson, Neil B.; Albu, Remus; Doherty, Marcus W.; Meriles, Carlos A.

2016-08-01

The nitrogen-vacancy (NV) centre in diamond is emerging as a promising platform for solid-state quantum information processing and nanoscale metrology. Of interest in these applications is the manipulation of the NV charge, which can be attained by optical excitation. Here, we use two-colour optical microscopy to investigate the dynamics of NV photo-ionization, charge diffusion and trapping in type-1b diamond. We combine fixed-point laser excitation and scanning fluorescence imaging to locally alter the concentration of negatively charged NVs, and to subsequently probe the corresponding redistribution of charge. We uncover the formation of spatial patterns of trapped charge, which we qualitatively reproduce via a model of the interplay between photo-excited carriers and atomic defects. Further, by using the NV as a probe, we map the relative fraction of positively charged nitrogen on localized optical excitation. These observations may prove important to transporting quantum information between NVs or to developing three-dimensional, charge-based memories.
Fe Isolated Single Atoms on S, N Codoped Carbon by Copolymer Pyrolysis Strategy for Highly Efficient Oxygen Reduction Reaction.

Science.gov (United States)

Li, Qiheng; Chen, Wenxing; Xiao, Hai; Gong, Yue; Li, Zhi; Zheng, Lirong; Zheng, Xusheng; Yan, Wensheng; Cheong, Weng-Chon; Shen, Rongan; Fu, Ninghua; Gu, Lin; Zhuang, Zhongbin; Chen, Chen; Wang, Dingsheng; Peng, Qing; Li, Jun; Li, Yadong

2018-06-01

Heteroatom-doped Fe-NC catalyst has emerged as one of the most promising candidates to replace noble metal-based catalysts for highly efficient oxygen reduction reaction (ORR). However, delicate controls over their structure parameters to optimize the catalytic efficiency and molecular-level understandings of the catalytic mechanism are still challenging. Herein, a novel pyrrole-thiophene copolymer pyrolysis strategy to synthesize Fe-isolated single atoms on sulfur and nitrogen-codoped carbon (Fe-ISA/SNC) with controllable S, N doping is rationally designed. The catalytic efficiency of Fe-ISA/SNC shows a volcano-type curve with the increase of sulfur doping. The optimized Fe-ISA/SNC exhibits a half-wave potential of 0.896 V (vs reversible hydrogen electrode (RHE)), which is more positive than those of Fe-isolated single atoms on nitrogen codoped carbon (Fe-ISA/NC, 0.839 V), commercial Pt/C (0.841 V), and most reported nonprecious metal catalysts. Fe-ISA/SNC is methanol tolerable and shows negligible activity decay in alkaline condition during 15 000 voltage cycles. X-ray absorption fine structure analysis and density functional theory calculations reveal that the incorporated sulfur engineers the charges on N atoms surrounding the Fe reactive center. The enriched charge facilitates the rate-limiting reductive release of OH* and therefore improved the overall ORR efficiency. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Adsorption of CH4 on nitrogen- and boron-containing carbon models of coal predicted by density-functional theory

Science.gov (United States)

Liu, Xiao-Qiang; Xue, Ying; Tian, Zhi-Yue; Mo, Jing-Jing; Qiu, Nian-Xiang; Chu, Wei; Xie, He-Ping

2013-11-01

Graphene doped by nitrogen (N) and/or boron (B) is used to represent the surface models of coal with the structural heterogeneity. Through the density functional theory (DFT) calculations, the interactions between coalbed methane (CBM) and coal surfaces have been investigated. Several adsorption sites and orientations of methane (CH4) on graphenes were systematically considered. Our calculations predicted adsorption energies of CH4 on graphenes of up to -0.179 eV, with the strongest binding mode in which three hydrogen atoms of CH4 direct to graphene surface, observed for N-doped graphene, compared to the perfect (-0.154 eV), B-doped (-0.150 eV), and NB-doped graphenes (-0.170 eV). Doping N in graphene increases the adsorption energies of CH4, but slightly reduced binding is found when graphene is doped by B. Our results indicate that all of graphenes act as the role of a weak electron acceptor with respect to CH4. The interactions between CH4 and graphenes are the physical adsorption and slightly depend upon the adsorption sites on graphenes and the orientations of methane as well as the electronegativity of dopant atoms in graphene.
Nitrogen-Doped Holey Graphene Film-Based Ultrafast Electrochemical Capacitors.

Science.gov (United States)

Zhou, Qinqin; Zhang, Miao; Chen, Ji; Hong, Jong-Dal; Shi, Gaoquan

2016-08-17

The commercialized aluminum electrolytic capacitors (AECs) currently used for alternating current (AC) line-filtering are usually the largest components in the electronic circuits because of their low specific capacitances and bulky sizes. Herein, nitrogen-doped holey graphene (NHG) films were prepared by thermal annealing the composite films of polyvinylpyrrolidone (PVP), graphene oxide (GO), and ferric oxide (Fe2O3) nanorods followed by chemical etching with hydrochloride acid. The typical electrochemical capacitor with NHG electrodes exhibited high areal and volumetric specific capacitances of 478 μF cm(-2) and 1.2 F cm(-3) at 120 Hz, ultrafast frequency response with a phase angle of -81.2° and a resistor-capacitor time constant of 203 μs at 120 Hz, as well as excellent cycling stability. Thus, it is promising to replace conventional AEC for AC line-filtering in miniaturized electronics.
Fabrication of Nitrogen-Doped Hollow Mesoporous Spherical Carbon Capsules for Supercapacitors.

Science.gov (United States)

Chen, Aibing; Xia, Kechan; Zhang, Linsong; Yu, Yifeng; Li, Yuetong; Sun, Hexu; Wang, Yuying; Li, Yunqian; Li, Shuhui

2016-09-06

A novel "dissolution-capture" method for the fabrication of nitrogen-doped hollow mesoporous spherical carbon capsules (N-HMSCCs) with high capability for supercapacitor is developed. The fabrication process is performed by depositing mesoporous silica on the surface of the polyacrylonitrile nanospheres, followed by a dissolution-capture process occurring in the polyacrylonitrile core and silica shell. The polyacrylonitrile core is dissolved by dimethylformamide treatment to form a hollow cavity. Then, the polyacrylonitrile is captured into the mesochannel of silica. After carbonization and etching of silica, N-HMSCCs with uniform mesopore size are produced. The N-HMSCCs show a high specific capacitance of 206.0 F g(-1) at a current density of 1 A g(-1) in 6.0 M KOH due to its unique hollow nanostructure, high surface area, and nitrogen content. In addition, 92.3% of the capacitance of N-HMSCCs still remains after 3000 cycles at 5 A g(-1). The "dissolution-capture" method should give a useful enlightenment for the design of electrode materials for supercapacitor.
Strong coupling between bi-dimensional electron gas and nitrogen localized states in heavily doped GaAs1-xN x structures

International Nuclear Information System (INIS)

Hamdouni, A.; Bousbih, F.; Ben Bouzid, S.; Oueslati, M.; Chtourou, R.; Harmand, J.C.

2005-01-01

We report a low-temperature photoluminescence spectra (LTPL) of GaAs 1-x N x layers and two-dimension electron gas (2DEG) GaAs 1-x N x /AlGaAs modulation doped heterostructure grown on GaAs substrates by molecular beam epitaxy (MBE) with low nitrogen content [N] = 2 x 10 18 cm -3 . At low temperature, PL spectra of GaAs 1-x N x layers are governed by several features associate to the excitons bound to nitrogen complexes, these features disappear in (2DEG) GaAs 1-x N x /AlGaAs modulation doped heterostructure and the PL peak energy decrease with the laser power excitation. This effect is explained by the strongly coupling of the (2DEG) fundamental state with the nitrogen localized states. An activated energy of about 55 meV is deduced by photoluminescence measurements in the 10-300 K range for a laser power excitation P = 6 W/cm 2
Nitrogen grain-boundary passivation of In-doped ZnO transparent conducting oxide

Science.gov (United States)

Ali, D.; Butt, M. Z.; Coughlan, C.; Caffrey, D.; Shvets, I. V.; Fleischer, K.

2018-04-01

We have investigated the properties and conduction limitations of spray pyrolysis grown, low-cost transparent conducting oxide ZnO thin films doped with indium. We analyze the optical, electrical, and crystallographic properties as functions of In content with a specific focus on postgrowth heat treatment of these thin films at 320 ∘C in an inert, nitrogen atmosphere, which improves the films electrical properties considerably. The effect was found to be dominated by nitrogen-induced grain-boundary passivation, identified by a combined study using i n situ resistance measurement upon annealing, x-ray photoelectron spectroscopy, photoluminescence, and x-ray diffraction studies. We also highlight the chemical mechanism of morphologic and crystallographic changes found in films with high indium content. By optimizing growth conditions according to these findings, ZnO:In with a resistivity as low as 2 ×10 -3Ω cm , high optical quality (T ≈90 % ), and sheet resistance of 32 Ω /□ has been obtained without any need for postgrowth treatments.
Nucleation, Growth Mechanism, and Controlled Coating of ZnO ALD onto Vertically Aligned N-Doped CNTs.

Science.gov (United States)

Silva, R M; Ferro, M C; Araujo, J R; Achete, C A; Clavel, G; Silva, R F; Pinna, N

2016-07-19

Zinc oxide thin films were deposited on vertically aligned nitrogen-doped carbon nanotubes (N-CNTs) by atomic layer deposition (ALD) from diethylzinc and water. The study demonstrates that doping CNTs with nitrogen is an effective approach for the "activation" of the CNTs surface for the ALD of metal oxides. Conformal ZnO coatings are already obtained after 50 ALD cycles, whereas at lower ALD cycles an island growth mode is observed. Moreover, the process allows for a uniform growth from the top to the bottom of the vertically aligned N-CNT arrays. X-ray photoelectron spectroscopy demonstrates that ZnO nucleation takes place at the N-containing species on the surface of the CNTs by the formation of the Zn-N bonds at the interface between the CNTs and the ZnO film.
Nitrogen doped silicon-carbon multilayer protective coatings on carbon obtained by TVA method

Science.gov (United States)

Ciupina, Victor; Vasile, Eugeniu; Porosnicu, Corneliu; Lungu, Cristian P.; Vladoiu, Rodica; Jepu, Ionut; Mandes, Aurelia; Dinca, Virginia; Caraiane, Aureliana; Nicolescu, Virginia; Cupsa, Ovidiu; Dinca, Paul; Zaharia, Agripina

2017-08-01

Protective nitrogen doped Si-C multilayer coatings on carbon, used to improve the oxidation resistance of carbon, were obtained by Thermionic Vacuum Arc (TVA) method. The initial carbon layer having a thickness of 100nm has been deposed on a silicon substrate in the absence of nitrogen, and then a 3nm Si thin film to cover carbon layer was deposed. Further, seven Si and C layers were alternatively deposed in the presence of nitrogen ions, each having a thickness of 40nm. In order to form silicon carbide at the interface between silicon and carbon layers, all carbon, silicon and nitrogen ions energy has increased up to 150eV . The characterization of microstructure and electrical properties of as-prepared N-Si-C multilayer structures were done using Transmission Electron Microscopy (TEM, STEM) techniques, Thermal Desorption Spectroscopy (TDS) and electrical measurements. Oxidation protection of carbon is based on the reaction between oxygen and silicon carbide, resulting in SiO2, SiO and CO2, and also by reaction involving N, O and Si, resulting in silicon oxynitride (SiNxOy) with a continuously variable composition, and on the other hand, since nitrogen acts as a trapping barrier for oxygen. To perform electrical measurements, 80% silver filled two-component epoxy-based glue ohmic contacts were attached on the N-Si-C samples. Electrical conductivity was measured in constant current mode. The experimental data show the increase of conductivity with the increase of the nitrogen content. To explain the temperature behavior of electrical conductivity we assumed a thermally activated electric transport mechanism.
Adsorption Energies of Carbon, Nitrogen, and Oxygen Atoms on the Low-temperature Amorphous Water Ice: A Systematic Estimation from Quantum Chemistry Calculations

Science.gov (United States)

Shimonishi, Takashi; Nakatani, Naoki; Furuya, Kenji; Hama, Tetsuya

2018-03-01

We propose a new simple computational model to estimate the adsorption energies of atoms and molecules to low-temperature amorphous water ice, and we present the adsorption energies of carbon (3 P), nitrogen (4 S), and oxygen (3 P) atoms based on quantum chemistry calculations. The adsorption energies were estimated to be 14,100 ± 420 K for carbon, 400 ± 30 K for nitrogen, and 1440 ± 160 K for oxygen. The adsorption energy of oxygen is consistent with experimentally reported values. We found that the binding of a nitrogen atom is purely physisorption, while that of a carbon atom is chemisorption, in which a chemical bond to an O atom of a water molecule is formed. That of an oxygen atom has a dual character, with both physisorption and chemisorption. The chemisorption of atomic carbon also implies the possibility of further chemical reactions to produce molecules bearing a C–O bond, though this may hinder the formation of methane on water ice via sequential hydrogenation of carbon atoms. These properties would have a large impact on the chemical evolution of carbon species in interstellar environments. We also investigated the effects of newly calculated adsorption energies on the chemical compositions of cold dense molecular clouds with the aid of gas-ice astrochemical simulations. We found that abundances of major nitrogen-bearing molecules, such as N2 and NH3, are significantly altered by applying the calculated adsorption energy, because nitrogen atoms can thermally diffuse on surfaces, even at 10 K.
Effects of doping in 25-atom bimetallic nanocluster catalysts for carbon–carbon coupling reaction of iodoanisole and phenylacetylene

Directory of Open Access Journals (Sweden)

Zhimin Li

2016-10-01

Full Text Available We here report the catalytic effects of foreign atoms (Cu, Ag, and Pt doped into well-defined 25-gold-atom nanoclusters. Using the carbon-carbon coupling reaction of p-iodoanisole and phenylacetylene as a model reaction, the gold-based bimetallic MxAu25−x(SR18 (–SR=–SCH2CH2Ph nanoclusters (supported on titania were found to exhibit distinct effects on the conversion of p-iodoanisole as well as the selectivity for the Sonogashira cross-coupling product, 1-methoxy-4-(2-phenylethynylbenzene. Compared to Au25(SR18, the centrally doped Pt1Au24(SR18 causes a drop in catalytic activity but with the selectivity retained, while the AgxAu25−x(SR18 nanoclusters gave an overall performance comparable to Au25(SR18. Interestingly, CuxAu25−x(SR18 nanoclusters prefer the Ullmann homo-coupling pathway and give rise to product 4,4′-dimethoxy-1,1′-biphenyl, which is in opposite to the other three nanocluster catalysts. Our overall conclusion is that the conversion of p-iodoanisole is largely affected by the electronic effect in the bimetallic nanoclusters’ 13-atom core (i.e., Pt1Au12, CuxAu13−x, and Au13, with the exception of Ag doping, and that the selectivity is primarily determined by the type of atoms on the MxAu12−x shell (M=Ag, Cu, and Au in the nanocluster catalysts.
Heavily Graphitic-Nitrogen Self-doped High-porosity Carbon for the Electrocatalysis of Oxygen Reduction Reaction

Science.gov (United States)

Feng, Tong; Liao, Wenli; Li, Zhongbin; Sun, Lingtao; Shi, Dongping; Guo, Chaozhong; Huang, Yu; Wang, Yi; Cheng, Jing; Li, Yanrong; Diao, Qizhi

2017-11-01

Large-scale production of active and stable porous carbon catalysts for oxygen reduction reaction (ORR) from protein-rich biomass became a hot topic in fuel cell technology. Here, we report a facile strategy for synthesis of nitrogen-doped porous nanocarbons by means of a simple two-step pyrolysis process combined with the activation of zinc chloride and acid-treatment process, in which kidney bean via low-temperature carbonization was preferentially adopted as the only carbon-nitrogen sources. The results show that this carbon material exhibits excellent ORR electrocatalytic activity, and higher durability and methanol-tolerant property compared to the state-of-the-art Pt/C catalyst for the ORR, which can be mainly attributed to high graphitic-nitrogen content, high specific surface area, and porous characteristics. Our results can encourage the synthesis of high-performance carbon-based ORR electrocatalysts derived from widely-existed natural biomass.
Synthesis of nitrogen doped microporous carbons prepared by activation-free method and their high electrochemical performance

International Nuclear Information System (INIS)

Kim, Ki-Seok; Park, Soo-Jin

2011-01-01

Graphical abstract: This describes the increase of specific capacitance in hybrid electrodes as a function of melamine content. Display Omitted Highlights: → For N-enriched hybrid carbons, co-precursors, PVDF/melamine composites, were used. → Microporous carbons were formed by only carbonization without chemical activation. → The nitrogen content of microporous carbons was controlled by melamine content. → N-doped carbons showed higher specific capacitance compared to microporous carbons. → It was attributed to the easy electron transfer and pseudocapacitance. - Abstract: Nitrogen-doped microporous carbons (N-MCs) were prepared by the carbonization of the polyvinylidene fluoride (PVDF)/melamine mixture without chemical activation. The electrochemical performance of the N-MCs was investigated as a function of PVDF/melamine ratio. It was found that, without additional activation, the N-MCs had a high specific surface area (greater than 560 m 2 /g) because of the micropore formation by the release of fluorine groups. In addition, although the specific surface area decreased, nitrogen groups were increased with increasing melamine content, leading to an enhanced electrochemical performance. Indeed, the N-MCs showed a better electrochemical performance than that of microporous carbons (MCs) prepared by PVDF alone, and the highest specific capacitance (310 F/g) was obtained at a current density of 0.5 A/g, as compared to a value of 248 F/g for MCs. These results indicate that the microporous features of N-MC lead to feasible ion transfer during charge/discharge duration and the presence of nitrogen groups as strong electron donor on the N-MC electrode in electrolyte could provide a pseudocapacitance by the redox reaction.
Pomelo peels-derived porous activated carbon microsheets dual-doped with nitrogen and phosphorus for high performance electrochemical capacitors

Science.gov (United States)

Wang, Zhen; Tan, Yongtao; Yang, Yunlong; Zhao, Xiaoning; Liu, Ying; Niu, Lengyuan; Tichnell, Brandon; Kong, Lingbin; Kang, Long; Liu, Zhen; Ran, Fen

2018-02-01

In this work, biomass pomelo peel is used to fabricate the porous activated carbon microsheets, and diammonium hydrogen phosphate (DHP) is employed to dual-dope carbon with nitrogen and phosphorus elements. With the benefit of DHP inducement and dual-doping of nitrogen and phosphorus, the prepared carbon material has a higher carbon yield, and exhibits higher specific surface area (about 807.7 m2/g), and larger pore volume (about 0.4378 cm3/g) with hierarchically structure of interconnected thin microsheets compared to the pristine carbon. The material exhibits not only high specific capacitance (240 F/g at 0.5 A/g), but also superior cycling performance (approximately 100% of capacitance retention after 10,000 cycles at 2 A/g) in 2 M KOH aqueous electrolyte. Furthermore, the assembled symmetric electrochemical capacitor in 1 M Na2SO4 aqueous electrolyte exhibits a high energy density of 11.7 Wh/kg at a power density of 160 W/kg.
Iron and Nitrogen doped Titania an Overview of Function and Application

International Nuclear Information System (INIS)

Kasap, M.

2008-01-01

Titanium dioxide is an exceptional material, featuring high transparency in the visible-IR range, high photo activity and superhidrophilicity, physical and chemical stability, low cost, non-toxicity. It is mostly applied in selective oxidation and reduction of an organic and organic materials, photovoltaics, photocatalytic sterilization, and sensors. Upon illumination of the TiO 2 surface with UV photons having energies in excess of 3.0 - 3.2 eV, electron-hole pairs are generated by interband transitions. The charge carriers migrate to the surface and react with the adsorbed water and oxygen, the -OH radicals thus formed being responsible for the highly enhanced chemical reactions with other adsorbates. To extend the amount of usable solar energy involved in TiO 2 surface catalyse, shifting the absorption edge towards the blue range of the visible spectrum (λ≥390-450 nm), several means have been proposed (attaching various organic dyes to the surface, reduction by hydrogenation, doping with various anions/cations etc.), each means with specific advantages and drawbacks. The most important restriction in all cases is the need to keep the lower limit of the conduction band non altered by band gap narrowing. Adequate doping of the titania materials may result in high-efficiency stable photocatalytic materials, sensitive enough to be photo-activated by low-level indoor light sources. We report here some of our latest results in preparing and characterizing Fe:TiO 2 and N:TiO-2 thin films using the RF magnetron sputtering and distinct growth conditions (pellet and discharge gas mixing, respectively). The as-deposited Fe:TiO 2 films, 300 nm thick, had a Fe/Ti concentration ratio ranging between 0.0% and 0.9%. While the low Fe-content samples were amorphous, an anatase Fe-rich nanophase dispersed in the amorphous phase was present in the high-content Fe films. Crystalline anatase and rutile nanodomains have been found in the nitrogen-containing titania films, with the
Reactions of Ground State Nitrogen Atoms N(4S) with Astrochemically-Relevant Molecules on Interstellar Dusts

Science.gov (United States)

Krim, Lahouari; Nourry, Sendres

2015-06-01

In the last few years, ambitious programs were launched to probe the interstellar medium always more accurately. One of the major challenges of these missions remains the detection of prebiotic compounds and the understanding of reaction pathways leading to their formation. These complex heterogeneous reactions mainly occur on icy dust grains, and their studies require the coupling of laboratory experiments mimicking the extreme conditions of extreme cold and dilute media. For that purpose, we have developed an original experimental approach that combine the study of heterogeneous reactions (by exposing neutral molecules adsorbed on ice to non-energetic radicals H, OH, N...) and a neon matrix isolation study at very low temperatures, which is of paramount importance to isolate and characterize highly reactive reaction intermediates. Such experimental approach has already provided answers to many questions raised about some astrochemically-relevant reactions occurring in the ground state on the surface of dust grain ices in dense molecular clouds. The aim of this new present work is to show the implication of ground state atomic nitrogen on hydrogen atom abstraction reactions from some astrochemically-relevant species, at very low temperatures (3K-20K), without providing any external energy. Under cryogenic temperatures and with high barrier heights, such reactions involving N(4S) nitrogen atoms should not occur spontaneously and require an initiating energy. However, the detection of some radicals species as byproducts, in our solid samples left in the dark for hours at 10K, proves that hydrogen abstraction reactions involving ground state N(4S) nitrogen atoms may occur in solid phase at cryogenic temperatures. Our results show the efficiency of radical species formation stemming from non-energetic N-atoms and astrochemically-relevant molecules. We will then discuss how such reactions, involving nitrogen atoms in their ground states, might be the first key step

Self-doped carbon architectures with heteroatoms containing nitrogen, oxygen and sulfur as high-performance anodes for lithium- and sodium-ion batteries

International Nuclear Information System (INIS)

Lu, Mingjie; Yu, Wenhua; Shi, Jing; Liu, Wei; Chen, Shougang; Wang, Xin; Wang, Huanlei

2017-01-01

Highlights: •Self-doped carbon architectures with nitrogen, oxygen, and sulfur are derived from Carrageen. •The obtained carbon materials exhibit excellent electrochemical property. •The strategy provides a one-step synthesis route to design advanced anodes for batteries. -- Abstract: Nitrogen, oxygen and sulfur tridoped porous carbons have been successfully synthesized from natural biomass algae-Carrageen by using a simultaneous carbonization and activation procedure. The doped carbons with sponge-like interconnected architecture, partially ordered graphitic structure, and abundant heteroatom doping perform outstanding features for electrochemical energy storage. When tested as lithium-ion battery anodes, a high reversible capacity of 839 mAh g −1 can be obtained at the current density of 0.1 A g −1 after 100 cycles, while a high capacity of 228 mAh g −1 can be maintained at 10 A g −1 . Tested against sodium, a high specific capacity of 227 can be delivered at 0.1 A g −1 after 100 cycles, while a high capacity of 109 mAh g −1 can be achieved at 10 A g −1 . These results turn out that the doped carbons would be potential anode materials for lithium- and sodium-ion batteries, which can be achieved by a one-step and large-scale synthesis route. Our observation indicates that heteroatom doping (especially sulfur) can significantly promote ion storage and reduce irreversible ion trapping to some extent. This work gives a general route for designing carbon nanostructures with heteroatom doping for efficient energy storage.
An all-carbon vdW heterojunction composed of penta-graphene and graphene: Tuning the Schottky barrier by electrostatic gating or nitrogen doping

Science.gov (United States)

Guo, Yaguang; Wang, Fancy Qian; Wang, Qian

2017-08-01

The non-zero band gap together with other unique properties endows penta-graphene with potential for device applications. Here, we study the performance of penta-graphene as the channel material contacting with graphene to form a van der Waals heterostructure. Based on first-principles calculations, we show that the intrinsic properties of penta-graphene are preserved in the heterojunction, which is different from the conventional contact with metal surfaces. The stacked system forms an n-type Schottky barrier (Φe) at the vertical interface, while a negative band bending occurs at the lateral interface in a current-in-plane model. From the device point of view, we further demonstrate that a low-Φe or an Ohmic contact can be realized by applying an external electric field or doping graphene with nitrogen atoms. This allows the control of the Schottky barrier height, which is essential in fabricating penta-graphene-based nanotransistors.
In Situ High-Level Nitrogen Doping into Carbon Nanospheres and Boosting of Capacitive Charge Storage in Both Anode and Cathode for a High-Energy 4.5 V Full-Carbon Lithium-Ion Capacitor.

Science.gov (United States)

Sun, Fei; Liu, Xiaoyan; Wu, Hao Bin; Wang, Lijie; Gao, Jihui; Li, Hexing; Lu, Yunfeng

2018-05-02

To circumvent the imbalances of electrochemical kinetics and capacity between Li + storage anodes and capacitive cathodes for lithium-ion capacitors (LICs), we herein demonstrate an efficient solution by boosting the capacitive charge-storage contributions of carbon electrodes to construct a high-performance LIC. Such a strategy is achieved by the in situ and high-level doping of nitrogen atoms into carbon nanospheres (ANCS), which increases the carbon defects and active sites, inducing more rapidly capacitive charge-storage contributions for both Li + storage anodes and PF 6 - storage cathodes. High-level nitrogen-doping-induced capacitive enhancement is successfully evidenced by the construction of a symmetric supercapacitor using commercial organic electrolytes. Coupling a pre-lithiated ANCS anode with a fresh ANCS cathode enables a full-carbon LIC with a high operating voltage of 4.5 V and high energy and power densities thereof. The assembled LIC device delivers high energy densities of 206.7 and 115.4 Wh kg -1 at power densities of 0.225 and 22.5 kW kg -1 , respectively, as well as an unprecedented high-power cycling stability with only 0.0013% capacitance decay per cycle within 10 000 cycles at a high power output of 9 kW kg -1 .
The atomic weight and isotopic composition of nitrogen and their variation in nature

International Nuclear Information System (INIS)

Holden, N.E.

1987-01-01

Two stable isotopes of nitrogen exist in nature, 14 N and 15 N. The less abundant isotope, 15 N, was discovered in 1929 by Naude, who studied the band spectra of nitric oxide, NO. However, the main source of a standard for this element is the air in the atmosphere, which is made up of approximately 78% N 2 . Reviewed in this paper is the measurements of the isotopic composition in air and its variation around the world. Also investigated is the variation of the isotopic composition in the various compounds or sources of nitrogen compared to the value in air. Data on the atomic weight and non-terrestrial data for nitrogen is also reviewed
Advanced Mechanical Properties of a Powder Metallurgy Ti-Al-N Alloy Doped with Ultrahigh Nitrogen Concentration

Science.gov (United States)

Shen, J.; Chen, B.; Umeda, J.; Kondoh, K.

2018-03-01

Titanium and its alloys are recognized for their attractive properties. However, high-performance Ti alloys are often alloyed with rare or noble-metal elements. In the present study, Ti alloys doped with only ubiquitous elements were produced via powder metallurgy. The experimental results showed that pure Ti with 1.5 wt.% AlN incorporated exhibited excellent tensile properties, superior to similarly extruded Ti-6Al-4V. Further analysis revealed that its remarkably advanced strength could primarily be attributed to nitrogen solid-solution strengthening, accounting for nearly 80% of the strength increase of the material. In addition, despite the ultrahigh nitrogen concentration up to 0.809 wt.%, the Ti-1.5AlN sample showed elongation to failure of 10%. This result exceeds the well-known limitation for nitrogen (over 0.45 wt.%) that causes embrittlement of Ti alloys.
Ultrasmall Tin Nanodots Embedded in Nitrogen-Doped Mesoporous Carbon: Metal-Organic-Framework Derivation and Electrochemical Application as Highly Stable Anode for Lithium Ion Batteries

International Nuclear Information System (INIS)

Dai, Ruoling; Sun, Weiwei; Wang, Yong

2016-01-01

Highlights: • Sn-based metal-organic-framework (MOF) is prepared. • Ultrasmall tin nanodots (2–3 nm) are embedded in nitrogen-doped mesoporous carbon. • The Sn/C composite anode shows high capacity and ultralong cycle life. - Abstract: This work reports a facile metal-organic-framework based approach to synthesize Sn/C composite, in which ultrasmall Sn nanodots with typical size of 2–3 nm are uniformly embedded in the nitrogen-doped porous carbon matrix (denoted as Sn@NPC). The effect of thermal treatment and nitrogen doping are also explored. Owing to the delicate size control and confined volume change within carbon matrix, the Sn@NPC composite can exhibit reversible capacities of 575 mAh g −1 (Sn contribution: 1091 mAh g −1 ) after 500 cycles at 0.2 A g −1 and 507 mAh g −1 (Sn contribution: 1077 mAh g −1 ) after 1500 cycles at 1 A g −1 . The excellent long-life electrochemical stability of the Sn@NPC anode has been mainly attributed to the uniform distribution of ultrasmall Sn nanodots and the highly-conductive and flexible N-doped carbon matrix, which can effectively facilitate lithium ion/electron diffusion, buffer the large volume change and improve the structure stability of the electrode during repetitive cycling with lithium ions.
Hydrothermal synthesis of NiCo2O4 nanowires/nitrogen-doped graphene for high-performance supercapacitor

International Nuclear Information System (INIS)

Yu, Mei; Chen, Jianpeng; Ma, Yuxiao; Zhang, Jingdan; Liu, Jianhua; Li, Songmei; An, Junwei

2014-01-01

Highlights: • NCO/NG composites were synthesized in a water–glycerol mixed solvent via hydrothermal treatment and subsequent calcination. • NiCo 2 O 4 nanowires are dispersed on NG nanosheets and the composite has porous structure. • The NCO/NG composite exhibits a high specific capacitance and long cycling performance. - Abstract: NiCo 2 O 4 nanowires/nitrogen-doped graphene (NCO/NG) composite materials were synthesized by hydrothermal treatment in a water–glycerol mixed solvent and subsequent thermal transformation. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. The electrochemical performance of the composites was evaluated by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectrum techniques. NiCo 2 O 4 nanowires are densely coated by nitrogen-doped graphene and the composite displays good electrochemical performance. The maximum specific capacitance of NCO/NG is 1273.13 F g −1 at 0.5 A g −1 in 6 M KOH aqueous solution, and it exhibits good capacity retention without noticeable degradation after 3000 cycles at 4 A g −1
Enhanced photocatalytic activity for H2 evolution under irradiation of UV-vis light by Au-modified nitrogen-doped TiO2.

Science.gov (United States)

Zhao, Weirong; Ai, Zhuyu; Dai, Jiusong; Zhang, Meng

2014-01-01

Photocatalytic water splitting for hydrogen evolution is a potential way to solve many energy and environmental issues. Developing visible-light-active photocatalysts to efficiently utilize sunlight and finding proper ways to improve photocatalytic activity for H2 evolution have always been hot topics for research. This study attempts to expand the use of sunlight and to enhance the photocatalytic activity of TiO2 by N doping and Au loading. Au/N-doped TiO2 photocatalysts were synthesized and successfully used for photocatalytic water splitting for H2 evolution under irradiation of UV and UV-vis light, respectively. The samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and photoelectrochemical characterizations. DRS displayed an extension of light absorption into the visible region by doping of N and depositing with Au, respectively. PL analysis indicated electron-hole recombination due to N doping and an efficient inhibition of electron-hole recombination due to the loaded Au particles. Under the irradiation of UV light, the photocatalytic hydrogen production rate of the as-synthesized samples followed the order Au/TiO2 > Au/N-doped TiO2 > TiO2 > N-doped TiO2. While under irradiation of UV-vis light, the N-TiO2 and Au/N-TiO2 samples show higher H2 evolution than their corresponding nitrogen-free samples (TiO2 and Au/TiO2). This inconsistent result could be attributed to the doping of N and the surface plasmonic resonance (SPR) effect of Au particles extending the visible light absorption. The photoelectrochemical characterizations further indicated the enhancement of the visible light response of Au/N-doped TiO2. Comparative studies have shown that a combination of nitrogen doping and Au loading enhanced the visible light response of TiO2 and increased the utilization of solar energy, greatly
Enhanced photocatalytic activity for H2 evolution under irradiation of UV-vis light by Au-modified nitrogen-doped TiO2.

Directory of Open Access Journals (Sweden)

Weirong Zhao

Full Text Available BACKGROUND PURPOSE: Photocatalytic water splitting for hydrogen evolution is a potential way to solve many energy and environmental issues. Developing visible-light-active photocatalysts to efficiently utilize sunlight and finding proper ways to improve photocatalytic activity for H2 evolution have always been hot topics for research. This study attempts to expand the use of sunlight and to enhance the photocatalytic activity of TiO2 by N doping and Au loading. METHODS: Au/N-doped TiO2 photocatalysts were synthesized and successfully used for photocatalytic water splitting for H2 evolution under irradiation of UV and UV-vis light, respectively. The samples were characterized using X-ray diffraction (XRD, transmission electron microscopy (TEM, X-ray photoelectron spectroscopy (XPS, UV-vis diffuse reflectance spectroscopy (DRS, photoluminescence spectroscopy (PL, and photoelectrochemical characterizations. RESULTS: DRS displayed an extension of light absorption into the visible region by doping of N and depositing with Au, respectively. PL analysis indicated electron-hole recombination due to N doping and an efficient inhibition of electron-hole recombination due to the loaded Au particles. Under the irradiation of UV light, the photocatalytic hydrogen production rate of the as-synthesized samples followed the order Au/TiO2 > Au/N-doped TiO2 > TiO2 > N-doped TiO2. While under irradiation of UV-vis light, the N-TiO2 and Au/N-TiO2 samples show higher H2 evolution than their corresponding nitrogen-free samples (TiO2 and Au/TiO2. This inconsistent result could be attributed to the doping of N and the surface plasmonic resonance (SPR effect of Au particles extending the visible light absorption. The photoelectrochemical characterizations further indicated the enhancement of the visible light response of Au/N-doped TiO2. CONCLUSION: Comparative studies have shown that a combination of nitrogen doping and Au loading enhanced the visible light response of
Iron, nitrogen and silicon doped diamond like carbon (DLC) thin films: A comparative study

International Nuclear Information System (INIS)

Ray, Sekhar C.; Pong, W.F.; Papakonstantinou, P.

2016-01-01

The X-ray absorption near edge structure (XANES), X-ray photoelectron spectroscopy (XPS), valence band photoemission (VB-PES) and Raman spectroscopy results show that the incorporation of nitrogen in pulsed laser deposited diamond like carbon (DLC) thin films, reverts the sp"3 network to sp"2 as evidenced by an increase of the sp"2 cluster and I_D/I_G ratio in C K-edge XANES and Raman spectra respectively which reduces the hardness/Young's modulus into the film network. Si-doped DLC film deposited in a plasma enhanced chemical vapour deposition process reduces the sp"2 cluster and I_D/I_G ratio that causes the decrease of hardness/Young's modulus of the film structure. The Fe-doped DLC films deposited by dip coating technique increase the hardness/Young's modulus with an increase of sp"3-content in DLC film structure. - Highlights: • Fe, N and Si doped DLC films deposited by dip, PLD and PECVD methods respectively • DLC:Fe thin films have higher hardness/Young's modulus than DLC:N(:Si) thin films. • sp"3 and sp"2 contents are estimated from C K-edge XANES and VB-PES measurements.
Large magnetoresistance effect in nitrogen-doped silicon

Directory of Open Access Journals (Sweden)

Tao Wang

2017-05-01

Full Text Available In this work, we reported a large magnetoresistance effect in silicon by ion implantation of nitrogen atoms. At room temperature, the magnetoresistance of silicon reaches 125 % under magnetic field 1.7 T and voltage bias -80 V. By applying an alternating magnetic field with a frequency (f of 0.008 Hz, we find that the magnetoresistance of silicon is divided into f and 2f two signal components, which represent the linear and quadratic magnetoresistance effects, respectively. The analysis based on tuning the magnetic field and the voltage bias reveals that electric-field-induced space-charge effect plays an important role to enhance both the linear and quadratic magnetoresistance effects. Observation as well as a comprehensive explanation of large MR in silicon, especially based on semiconductor CMOS implantation technology, will be an important progress towards magnetoelectronic applications.
Towards the atomic-scale characterization of isolated iron sites confined in a nitrogen-doped graphene matrix

Energy Technology Data Exchange (ETDEWEB)

Liu, Qingfei; Liu, Yun; Li, Haobo [State Key Laboratory of Catalysis, CAS Center for Excellence in Nanoscience, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023 (China); University of Chinese Academy of Sciences, Beijing, 100039 (China); Li, Lulu [College of Chemistry, Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian, 116023 (China); Deng, Dehui [State Key Laboratory of Catalysis, CAS Center for Excellence in Nanoscience, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023 (China); Yang, Fan, E-mail: fyang@dicp.ac.cn [State Key Laboratory of Catalysis, CAS Center for Excellence in Nanoscience, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023 (China); Bao, Xinhe, E-mail: xhbao@dicp.ac.cn [State Key Laboratory of Catalysis, CAS Center for Excellence in Nanoscience, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023 (China)

2017-07-15

Highlights: • Local atomic and electronic structure of the Fe-N-C catalyst characterized by STM and STS. • The combination of air-AFM, UHV-STM and DFT calculations for the characterization of powder catalysts. • The selection of solvent is vital to the homogeneous dispersion of powder catalyst on a planar support. - Abstract: Atomic scale characterization of the surface structure of powder catalysts is essential to the identification of active sites, but remains a major challenge in catalysis research. We described here a procedure that combines atomic force microscopy (AFM), operated in air, and scanning tunneling microscopy (STM), operated in UHV, to obtain the atomic structure and local electronic properties of powder catalysts. The atomically dispersed Fe-N-C catalyst was used as an example, which was synthesized by low temperature ball milling methods. We discussed the effect of solvents in the dispersion of powder catalysts on a planar support, which is key to the subsequent atomic characterization. From the morphology, atomic structure and local electronic properties of the Fe-N-C catalyst, our combined measurements also provide an insight for the effect of ball milling in the preparation of atomically dispersed metal catalysts.
Synergistic effect of oxygen vacancy and nitrogen doping on enhancing the photocatalytic activity of Bi{sub 2}O{sub 2}CO{sub 3} nanosheets with exposed {0 0 1} facets for the degradation of organic pollutants

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yafei [School of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062 (China); Zhu, Gangqiang, E-mail: zgq2006@snnu.edu.cn [School of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062 (China); Hojamberdiev, Mirabbos [School of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062 (China); Department of Natural and Mathematic Sciences, Turin Polytechnic University in Tashkent, Kichik Halqa Yo’li 17, Tashkent 100095 (Uzbekistan); Gao, Jianzhi [School of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062 (China); Hao, Jing [Xi' an Rejee Industry Development Co., Ltd., Xi’an 710016 (China); Zhou, Jianping; Liu, Peng [School of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062 (China)

2016-05-15

Highlights: • Nitrogen-doped Bi{sub 2}O{sub 2}CO{sub 3} flower-like microstructures were synthesized by hydrothermal method. • Surface oxygen vacancy were obtained by irradiating the nitrogen-doped Bi{sub 2}O{sub 2}CO{sub 3} with UV light. • Photocatalytic activity was studied by degrading Rhodamine B. • A synergistic effect between oxygen vacancy and nitrogen doping in Bi{sub 2}O{sub 2}CO{sub 3}. - Abstract: Single-crystalline bare Bi{sub 2}O{sub 2}CO{sub 3} (BOC) nanosheets with exposed {0 0 1} facets and nitrogen-doped Bi{sub 2}O{sub 2}CO{sub 3} (NBOC) flower-like microstructures were synthesized by a simple hydrothermal method. The nitrogen-doped Bi{sub 2}O{sub 2}CO{sub 3} flower-like microstructures with oxygen vacancy (UV-NBOC) were obtained by irradiating the NBOC microstructures with UV light for 2 h in ethanol. The UV–vis diffuse reflectance spectra showed that the NBOC and UV-NBOC nanosheets exhibit an obvious red shift in light absorption band compared with the pure BOC nanosheets. Rhodamine B (RhB) was chosen as a model organic pollutant to verify the influence of oxygen vacancy and nitrogen doping on the photocatalytic activity of Bi{sub 2}O{sub 2}CO{sub 3} under simulated solar light irradiation. Judging from the kinetics of RhB photodegradation over the synthesized samples, a synergistic effect between oxygen vacancy and nitrogen doping was found with a remarkable increase (more than 10 and 2 times) in the photocatalytic activity of UV-NBOC compared with BOC and NBOC, respectively. Moreover, the UV-NBOC also exhibited an excellent cyclability and superior photocatalytic activity toward degradation of other organic pollutants (methylene blue, Congo red, Bisphenol A) under simulated solar light irradiation.
Solvent-induced synthesis of nitrogen-doped hollow carbon spheres with tunable surface morphology for supercapacitors

Science.gov (United States)

Liu, Feng; Yuan, Ren-Lu; Zhang, Ning; Ke, Chang-Ce; Ma, Shao-Xia; Zhang, Ru-Liang; Liu, Lei

2018-04-01

Nitrogen doped hollow carbon spheres (NHCSs) with tunable surface morphology have been prepared through one-pot carbonization method by using melamine-formaldehyde spheres as template and resorcinol-based resin as carbon precursor in ethanol-water solution. Well-dispersed NHCSs with particle size of 800 nm were obtained and the surface of NHCSs turn from smooth to tough, wrinkled, and finally concave by increasing the ethanol concentration. The fabricated NHCSs possessed high nitrogen content (3.99-4.83%) and hierarchical micro-dual mesoporous structure with surface area range of 265-405 m2 g-1 and total pore volume of 0.18-0.29 cm3 g-1, which contributed to high specific capacitance, excellent rate capability and long cycle life.
Visible sub-band gap photoelectron emission from nitrogen doped and undoped polycrystalline diamond films

Energy Technology Data Exchange (ETDEWEB)

Elfimchev, S., E-mail: sergeyel@tx.technion.ac.il; Chandran, M.; Akhvlediani, R.; Hoffman, A.

2017-07-15

Highlights: • Nitrogen related centers in diamond film are mainly responsible for visible sub-band-gap photoelectron emission. • The influence of film thickness and substrate on the measured photoelectron emission yields was not found. • Nanocrystalline diamonds have low electron emission yields most likely because of high amount of defects. • Visible sub-band gap photoelectron emission may increase with temperature due to electron trapping/detrapping processes. - Abstract: In this study the origin of visible sub-band gap photoelectron emission (PEE) from polycrystalline diamond films is investigated. The PEE yields as a function of temperature were studied in the wavelengths range of 360–520 nm. Based on the comparison of electron emission yields from diamond films deposited on silicon and molybdenum substrates, with different thicknesses and nitrogen doping levels, we suggested that photoelectrons are generated from nitrogen related centers in diamond. Our results show that diamond film thickness and substrate material have no significant influence on the PEE yield. We found that nanocrystalline diamond films have low electron emission yields, compared to microcrystalline diamond, due to the presence of high amount of defects in the former, which trap excited electrons before escaping into the vacuum. However, the low PEE yield of nanocrystalline diamond films was found to increase with temperature. The phenomenon was explained by the trap assisted photon enhanced thermionic emission (ta-PETE) model. According to the ta-PETE model, photoelectrons are trapped by shallow traps, followed by thermal excitation at elevated temperatures and escape into the vacuum. Activation energies of trap levels were estimated for undoped nanocrystalline, undoped microcrystalline and N-doped diamond films using the Richardson-Dushman equation, which gives 0.13, 0.39 and 0.04 eV, respectively. Such low activation energy of trap levels makes the ta-PETE process very
Surface passivation of n-type doped black silicon by atomic-layer-deposited SiO2/Al2O3 stacks

Science.gov (United States)

van de Loo, B. W. H.; Ingenito, A.; Verheijen, M. A.; Isabella, O.; Zeman, M.; Kessels, W. M. M.

2017-06-01

Black silicon (b-Si) nanotextures can significantly enhance the light absorption of crystalline silicon solar cells. Nevertheless, for a successful application of b-Si textures in industrially relevant solar cell architectures, it is imperative that charge-carrier recombination at particularly highly n-type doped black Si surfaces is further suppressed. In this work, this issue is addressed through systematically studying lowly and highly doped b-Si surfaces, which are passivated by atomic-layer-deposited Al2O3 films or SiO2/Al2O3 stacks. In lowly doped b-Si textures, a very low surface recombination prefactor of 16 fA/cm2 was found after surface passivation by Al2O3. The excellent passivation was achieved after a dedicated wet-chemical treatment prior to surface passivation, which removed structural defects which resided below the b-Si surface. On highly n-type doped b-Si, the SiO2/Al2O3 stacks result in a considerable improvement in surface passivation compared to the Al2O3 single layers. The atomic-layer-deposited SiO2/Al2O3 stacks therefore provide a low-temperature, industrially viable passivation method, enabling the application of highly n- type doped b-Si nanotextures in industrial silicon solar cells.
Green synthesis of nitrogen-doped graphitic carbon sheets with use of Prunus persica for supercapacitor applications

Energy Technology Data Exchange (ETDEWEB)

Atchudan, Raji, E-mail: atchudanr@yu.ac.kr [School of Chemical Engineering, Yeungnam University, Gyeongsan 38541 (Korea, Republic of); Edison, Thomas Nesakumar Jebakumar Immanuel [School of Chemical Engineering, Yeungnam University, Gyeongsan 38541 (Korea, Republic of); Perumal, Suguna [Department of Applied Chemistry, Kyungpook National University, Daegu 41566 (Korea, Republic of); Lee, Yong Rok, E-mail: yrlee@yu.ac.kr [School of Chemical Engineering, Yeungnam University, Gyeongsan 38541 (Korea, Republic of)

2017-01-30

Highlights: • N-GCSs was synthesized from the unripe Prunus persica by direct hydrothermal method. • The resulting N-GCSs-2 exhibit an excellent graphitization with 9.33% of nitrogen. • N-GCSs-2 provide high C{sub s} of 176 F g{sup −1} at current density of 0.1 A g{sup −1} in 1 M H{sub 2}SO{sub 4}. • N-GCSs-2 have high capacitance retention and 20% capacity growth after 2000 cycles. • First time, N-GCSs resulted from peach via green route for flexible supercapacitors. - Abstract: Nitrogen-doped graphitic carbon sheets (N-GCSs) were prepared from the extract of unripe Prunus persica fruit by a direct hydrothermal method. The synthesized N-GCSs were examined by high resolution transmission electron microscopy (HRTEM), nitrogen adsorption-desorption isotherms, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FT-IR) spectroscopy. HRTEM showed that the synthesized carbon sheets were graphitic with lattice fringes and an inter-layer distance of 0.36 nm. Doping with the nitrogen moiety present over the synthesized GCSs was confirmed by XPS, FT-IR spectroscopy, and energy dispersive X-ray spectroscopy elemental mapping. The fruit extract associated with hydrothermal-carbonization method is economical and eco-friendly with a single step process. The resulting carbon sheets could be modified and are promising candidates for nano-electronic applications, including supercapacitors. The synthesized N-GCSs-2 provided a high specific capacitance of 176 F g{sup −1} at a current density of 0.1 A g{sup −1}. This electrode material has excellent cyclic stability, even after 2000 cycles of charge-discharge at a current density of 0.5 A g{sup −1}.
Single Cobalt Atoms with Precise N-Coordination as Superior Oxygen Reduction Reaction Catalysts.

Science.gov (United States)

Yin, Peiqun; Yao, Tao; Wu, Yuen; Zheng, Lirong; Lin, Yue; Liu, Wei; Ju, Huanxin; Zhu, Junfa; Hong, Xun; Deng, Zhaoxiang; Zhou, Gang; Wei, Shiqiang; Li, Yadong

2016-08-26

A new strategy for achieving stable Co single atoms (SAs) on nitrogen-doped porous carbon with high metal loading over 4 wt % is reported. The strategy is based on a pyrolysis process of predesigned bimetallic Zn/Co metal-organic frameworks, during which Co can be reduced by carbonization of the organic linker and Zn is selectively evaporated away at high temperatures above 800 °C. The spherical aberration correction electron microscopy and extended X-ray absorption fine structure measurements both confirm the atomic dispersion of Co atoms stabilized by as-generated N-doped porous carbon. Surprisingly, the obtained Co-Nx single sites exhibit superior ORR performance with a half-wave potential (0.881 V) that is more positive than commercial Pt/C (0.811 V) and most reported non-precious metal catalysts. Durability tests revealed that the Co single atoms exhibit outstanding chemical stability during electrocatalysis and thermal stability that resists sintering at 900 °C. Our findings open up a new routine for general and practical synthesis of a variety of materials bearing single atoms, which could facilitate new discoveries at the atomic scale in condensed materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
A three-dimensional nitrogen-doped graphene structure: a highly efficient carrier of enzymes for biosensors

Science.gov (United States)

Guo, Jingxing; Zhang, Tao; Hu, Chengguo; Fu, Lei

2015-01-01

In recent years, graphene-based enzyme biosensors have received considerable attention due to their excellent performance. Enormous efforts have been made to utilize graphene oxide and its derivatives as carriers of enzymes for biosensing. However, the performance of these sensors is limited by the drawbacks of graphene oxide such as slow electron transfer rate, low catalytic area and poor conductivity. Here, we report a new graphene-based enzyme carrier, i.e. a highly conductive 3D nitrogen-doped graphene structure (3D-NG) grown by chemical vapour deposition, for highly effective enzyme-based biosensors. Owing to the high conductivity, large porosity and tunable nitrogen-doping ratio, this kind of graphene framework shows outstanding electrical properties and a large surface area for enzyme loading and biocatalytic reactions. Using glucose oxidase (GOx) as a model enzyme and chitosan (CS) as an efficient molecular binder of the enzyme, our 3D-NG based biosensors show extremely high sensitivity for the sensing of glucose (226.24 μA mM-1 m-2), which is almost an order of magnitude higher than those reported in most of the previous studies. The stable adsorption and outstanding direct electrochemical behaviour of the enzyme on the nanocomposite indicate the promising application of this 3D enzyme carrier in high-performance electrochemical biosensors or biofuel cells.In recent years, graphene-based enzyme biosensors have received considerable attention due to their excellent performance. Enormous efforts have been made to utilize graphene oxide and its derivatives as carriers of enzymes for biosensing. However, the performance of these sensors is limited by the drawbacks of graphene oxide such as slow electron transfer rate, low catalytic area and poor conductivity. Here, we report a new graphene-based enzyme carrier, i.e. a highly conductive 3D nitrogen-doped graphene structure (3D-NG) grown by chemical vapour deposition, for highly effective enzyme
Nitrogen and sulfur co-doped graphene/carbon nanotube as metal-free electrocatalyst for oxygen evolution reaction: the enhanced performance by sulfur doping

International Nuclear Information System (INIS)

Zhao, Jujiao; Liu, Yanming; Quan, Xie; Chen, Shuo; Zhao, Huimin; Yu, Hongtao

2016-01-01

Highlights: • Metal-free 3D architecture N,S co-doped GR/CNT is prepared by a one-step method. • N,S co-doped GR/CNT exhibits good activity and stability for OER. • S doping is indicated beneficial for OER performance of metal-free catalysts. • The catalytic kinetics is highly correlated with the content of C-S-C structure. • 3D architecture composed of GR and CNT also contributes to the OER activity. - Abstract: Highly active metal-free electrocatalysts consisting of earth-abundant elements for oxygen evolution reaction (OER) are extremely desired for renewable energy technologies. Here we prepare the nitrogen and sulfur co-doped graphene/carbon nanotube (NS-GR/CNT) with 3D architecture by one-step hydrothermal method, which presents good performance for OER. The as-prepared NS-GR/CNT exhibits more negative onset potential and lower Tafel slope (0.56 V, 103 mV decade"−"1 vs. S.C.E. in 0.1 M KOH) compared to single N doped graphene/carbon nanotube (0.65 V, 285 mV decade"−"1), which indicates S doping can significantly enhance the OER performance. The X-ray photoelectron spectroscopy reveals that the thiophene-like S (C-S-C) is the dominant S species in all the S doped samples. NS-GR/CNT with C-S-C content of 0.26% has the Tafel slope of 151 mV decade"−"1 while the value for NS-GR/CNT with C-S-C content of 1.09% is 103 mV decade"−"1. The decreased Tafel slope demonstrates the catalytic kinetics are highly correlated with the content of C-S-C. Density functional theory calculations suggest that C-S-C may improve the catalytic kinetics by facilitating the adsorption of the OH"− intermediate. Besides, the 3D architecture composed of graphene and CNTs also contributes to the good performance and chronoamperometric measurement demonstrates the good durability of NS-GR/CNTs.

Computational investigation of the co-doping effect of sulphur and nitrogen on the electronics of CsTaWO6

Directory of Open Access Journals (Sweden)

Liuxie Liu

2017-03-01

Full Text Available CsTaWO6 is a typical AMWO6-type compound and the photocatalysis of the pure and doped phases has been extensively studied experimentally. In this work, the electronic structures of sulphur (S and nitrogen (N co-doped CsTaWO6 have been studied in the framework of density functional theory, in particular the S/N co-doping effect has been investigated. It is found that, (i S/N co-dopants prefer to be separated; (ii middle-gap states are introduced by N and S-dopant at the edges of valence band and conduction band; and (iii Co-doping not only narrows the band gap, but also promotes the separation of photo-excited electrons and holes. Feature (iii has been identified as a key reason why S/N co-doped CsTaWO6 is more efficient in photocatalytic water-splitting. A general doping strategy has been further suggested: co-dopants which can dominate the frontier states and favour to be separated can offer excellent photocatalysis performance.
Enhanced electrochemical capacitance and oil-absorbability of N-doped graphene aerogel by using amino-functionalized silica as template and doping agent

Science.gov (United States)

Du, Yongxu; Liu, Libin; Xiang, Yu; Zhang, Qiang

2018-03-01

The development of novel energy storage devices with high power density and energy density is highly desired. However, as a promising material, the strong π-π interaction of graphene inhibits its applications. Herein, we provide a new approach that amino-functionalized silica are used as both templates to prevent the restacking of the graphene sheets and doping agents simultaneously. The microstructures, porous properties and chemical composition of the resulted N-doped reduced graphene oxide (RGO) aerogels, characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman, X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller measurement, indicate that the amount of SiO2-NH2 has profound effects on the surface area and carbon activity of the graphene sheets. Benefiting from the large specific surface area of 481.8 m2 g-1, low series resistances and high nitrogen doping content (4.4 atom%), the as-fabricated 3D hierarchical porous N-doped RGO aerogel electrode exhibits outstanding electrochemical performance in aqueous and organic electrolyte, such as ultrahigh specific capacitances of 350 F g-1 at a current density of 1 A g-1 and excellent reversibility with a cycling efficiency of 88% after 10000 cycles. In addition, the N-doped RGO aerogels possess high oil-absorbability with long recyclability.
Monodisperse Pt atoms anchored on N-doped graphene as efficient catalysts for CO oxidation: A first-principles investigation

KAUST Repository

Liu, Xin; Sui, Yanhui; Duan, Ting; Meng, Changgong; Han, Yu

2015-01-01

We performed first-principles based calculations to investigate the electronic structure and the potential catalytic performance of Pt atoms monodispersed on N-doped graphene in CO oxidation. We showed that N-doping can introduce localized defect states in the vicinity of the Fermi level of graphene which will effectively stabilize the deposited Pt atoms. The binding energy of a single Pt atom onto a stable cluster of 3 pyridinic N (PtN3) is up to -4.47 eV, making the diffusion and aggregation of anchored Pt atoms difficult. Both the reaction thermodynamics and kinetics suggest that CO oxidation over PtN3 would proceed through the Langmuir-Hinshelwood mechanism. The reaction barriers for the formation and dissociation of the peroxide-like intermediate are determined to be as low as 0.01 and 0.08 eV, respectively, while that for the regeneration is only 0.15 eV, proving the potential high catalytic performance of PtN3 in CO oxidation, especially at low temperatures. The Pt-d states that are up-shifted by the Pt-N interaction account for the enhanced activation of O2 and the efficient formation and dissociation of the peroxide-like intermediate.
One-pot synthesis of nitrogen and sulfur co-doped graphene supported MoS2 as high performance anode materials for lithium-ion batteries

International Nuclear Information System (INIS)

Liu, Qiuhong; Wu, Zhenjun; Ma, Zhaoling; Dou, Shuo; Wu, Jianghong; Tao, Li; Wang, Xin; Ouyang, Canbing; Shen, Anli; Wang, Shuangyin

2015-01-01

Highlights: • Nitrogen and sulfur co-doped graphene supported MoS 2 nanosheets were successfully prepared and used as anode materials for Li-ion batteries. • The as-prepared anode materials show excellent stability in Li-ion batteries. • The materials show high reversible capacity for lithium ion batteries. - Abstract: Nitrogen and sulfur co-doped graphene supported MoS 2 (MoS 2 /NS-G) nanosheets were prepared through a one-pot thermal annealing method. The as prepared samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectra and electrochemical techniques. The MoS 2 /NS-G shows high reversible capacity about 1200 mAh/g at current density of 150 mA/g and excellent stability in Li-ion batteries. It was demonstrated the co-doping of graphene by N and S could significantly enhance the durability of MoS 2 as anode materials for Li-ion batteries
Growth and characterization of nitrogen-doped TiO2 thin films prepared by reactive pulsed laser deposition

International Nuclear Information System (INIS)

Sauthier, G.; Ferrer, F.J.; Figueras, A.; Gyoergy, E.

2010-01-01

Nitrogen-doped titanium dioxide (TiO 2 ) thin films were grown on (001) SiO 2 substrates by reactive pulsed laser deposition. A KrF* excimer laser source (λ = 248 nm, τ FWHM ≅ 10 ns, ν = 10 Hz) was used for the irradiations of pressed powder targets composed by both anatase and rutile phase TiO 2 . The experiments were performed in a controlled reactive atmosphere consisting of oxygen or mixtures of oxygen and nitrogen gases. The obtained thin film crystal structure was investigated by X-ray diffraction, while their chemical composition as well as chemical bonding states between the elements were studied by X-ray photoelectron spectroscopy. An interrelation was found between nitrogen concentration, crystalline structure, bonding states between the elements, and the formation of titanium oxinitride compounds. Moreover, as a result of the nitrogen incorporation in the films a continuous red-shift of the optical absorption edge accompanied by absorption in the visible spectral range between 400 and 500 nm wavelength was observed.
Boron-doped Diamond Electrodes: Electrochemical, Atomic Force Microscopy and Raman Study towards Corrosion-modifications at Nanoscale

Czech Academy of Sciences Publication Activity Database

Kavan, Ladislav; Vlčková Živcová, Zuzana; Petrák, Václav; Frank, Otakar; Janda, Pavel; Tarábková, Hana; Nesladek, M.; Mortet, Vincent

2015-01-01

Roč. 179, OCT 2015 (2015), s. 626-636 ISSN 0013-4686 R&D Projects: GA ČR GA13-31783S Institutional support: RVO:61388955 ; RVO:68378271 Keywords : Raman spectroelectrochemistry * atomic force microscopy * boron doped diamond Subject RIV: CG - Electrochemistry Impact factor: 4.803, year: 2015
Chemical effects of alkali atoms on critical temperature in superconducting alkali-doped fullerides

Science.gov (United States)

Hetfleisch, F.; Gunnarsson, O.; Srama, R.; Han, J. E.; Stepper, M.; Roeser, H.-P.; Bohr, A.; Lopez, J. S.; Mashmool, M.; Roth, S.

2018-03-01

Alkali metal doped fullerides (A3C60) are superconductors with critical temperatures, Tc, extending up to 38 K. Tc is known to depend strongly on the lattice parameter a, which can be adjusted by physical or chemical pressure. In the latter case an alkali atom is replaced by a different sized one, which changes a. We have collected an extensive data base of experimental data for Tc from very early up to recent measurements. We disentangle alkali atom chemical effects on Tc, beyond the well-known consequences of changing a. It is found that Tc, for a fixed a, is typically increased as smaller alkali atoms are replaced by larger ones, except for very large a. Possible reasons for these results are discussed. Although smaller in size than the lattice parameter contribution, the chemical effect is not negligible and should be considered in future physical model developments.
Preferential incorporation of substitutional nitrogen near the atomic step edges in diluted nitride alloys

Energy Technology Data Exchange (ETDEWEB)

Cornet, C.; Nguyen Thanh, T.; Almosni, S.; Rohel, T.; Kuyyalil, J.; Rambaud, A.; Letoublon, A.; Bertru, N.; Durand, O.; Le Corre, A. [Universite Europeenne de Bretagne, INSA Rennes, France and CNRS, UMR 6082 Foton, 20 avenue des Buttes de Coeesmes, 35708 Rennes (France); Quinci, T. [Universite Europeenne de Bretagne, INSA Rennes, France and CNRS, UMR 6082 Foton, 20 avenue des Buttes de Coeesmes, 35708 Rennes (France); CEA LCP, INES, Savoie Technolac, 73375 Le Bourget du Lac (France)

2012-12-17

We have investigated the influence of the surface roughness on nitrogen incorporation during the molecular beam epitaxy of diluted nitrides, independently of the other growth parameters. GaPN/GaP layers grown simultaneously on surfaces displaying different roughnesses reveal a large difference in nitrogen incorporation despite the same growth temperature and growth rate. The same difference is found on quasi-lattice-matched GaAsPN demonstrating that the phenomenon is not related to any strain-induced mechanisms. The tendency is clearly confirmed when varying the growth conditions. As a direct consequence, the incorporation of substitutional nitrogen near the atomic step edges is found to be 6.7 times more probable than the in-plane nitrogen incorporation. The formation of N-N{sub i} clusters and their stability on the surface is discussed.
Density functional investigation of mercury and arsenic adsorption on nitrogen doped graphene decorated with palladium clusters: A promising heavy metal sensing material in farmland

International Nuclear Information System (INIS)

Zhao, Chunjiang; Wu, Huarui

2017-01-01

Highlights: • PNG can be acted as micro-sensor for monitoring heavy metal in agriculture. • The most favorable adsorption site of Pd atom or cluster on PNG is the vacancy site. • The Pd atom or cluster enhance the reactivity of PNG toward Hg and AsH_3 adsorption. • The efficiency of a sorbent can be tuned by tailoring the ε_d of adsorbed metals. - Abstract: Density functional theory calculations are carried out to study the adsorption of mercury and arsenic on Pd_n (n = 1–6) supported on pyridine-like nitrogen doped graphene (PNG). Owing to the promising sensitivity in trace amounts of atoms or molecules, PNG can be acted as micro-sensor for sensing heavy metals in agriculture soils. Through the analyses of structural and electronic properties of pristine PNG and Pd atom decorated PNG, we find that the most favorable adsorption site for Pd atom is the vacancy site. The analyses of structural and electronic properties reveal that the Pd atom or clusters can enhance the reactivity for Hg and AsH_3 adsorption on PNG. The adsorption ability of Hg on Pd_n decorated PNG is found to be related to the d-band center (ε_d) of the Pd_n, in which the closer ε_d of Pd_n to the Fermi level, the higher adsorption strength for Hg on Pd_n decorated PNG. Moreover, the charge transfer between Pd_n and arsenic may constitute arsenic adsorption on Pd_n decorated PNG. Further design of highly efficient carbon based sorbents for heavy metals removal should be focused on tailoring ε_d of adsorbed metals.
Electrochemical study of a novel high performance supercapacitor based on MnO{sub 2}/nitrogen-doped graphene nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Naderi, Hamid Reza, E-mail: hrnaderi@ut.ac.ir [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Norouzi, Parviz, E-mail: norouzi@khayam.ut.ac.ir [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Biosensor Research Center, Endocrinology & Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Ganjali, Mohammad Reza, E-mail: ganjali@khayam.ut.ac.ir [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Biosensor Research Center, Endocrinology & Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of)

2016-03-15

Graphical abstract: - Highlights: • MnO{sub 2} nanoparticles was prepared by sonochemical method. • MnO{sub 2} are anchored on the surface of nitrogen-doped reduced graphene oxide (NRGO). • MnO{sub 2}/NRGO nanocomposite show high capacitance, good rate and cycling performance. • The nanocomposite electrode exhibits specific capacitance of 522 F g{sup −1} in 2 mV s{sup −1}. • The electrode reveals 97% retention of initial capacitance after 4000 cycles. - Abstract: A new nanocomposite was synthesized via deposition of MnO{sub 2} on Nitrogen-doped reduced graphene (MnO{sub 2}/NRGO) by sonochemical method, in which, the particles of manganese oxide were uniformly distributed on NRGO sheets. The structure and morphology of MnO{sub 2}/NRGO nanocomposites are characterized by X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The electrochemical supercapacitive performance of the nanocomposite was investigated by cyclic voltammetry (CV), continuous cyclic voltammetry (CCV), galvanostatic charge/discharge, and electrochemical impedance spectroscopy (EIS) methods. The MnO{sub 2}/NRGO nanocomposite shows enhanced specific capacitance of 522 F g{sup −1} at 2 mV s{sup −1} and its high synergistic effect was compared with MnO{sub 2}/RGO. The high specific capacitance and exceptionally high cyclic stability of MnO{sub 2}/NRGO attributes to the doping of nitrogen and uniform dispersion of MnO{sub 2} particles on NRGO. The CCV showed that the capacity retention for MnO{sub 2}/NRGO and MnO{sub 2}/RGO still maintained at 96.3% and 93% after 4000 CVs. The improved supercapacitive performance enables this nanocomposite as efficient electrode material for supercapacitor electrodes.
Magnetic properties of Mg12O12 nanocage doped with transition metal atoms (Mn, Fe, Co and Ni): DFT study

Science.gov (United States)

Javan, Masoud Bezi

2015-07-01

Binding energy of the Mg12O12 nanocage doped with transition metals (TM=Mn, Fe, Co and Ni) in endohedrally, exohedrally and substitutionally forms were studied using density functional theory with the generalized gradient approximation exchange-correlation functional along 6 different paths inside and outside of the Mg12O12 nanocage. The most stable structures were determined with full geometry optimization near the minimum of the binding energy curves of all the examined paths inside and outside of the Mg12O12 nanocage. The results reveal that for all stable structures, the Ni atom has a larger binding energy than the other TM atoms. It is also found that for all complexes additional peaks contributed by TM-3d, 4s and 4p states appear in the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) gap of the host MgO cluster. The mid-gap states are mainly due to the hybridization between TM-3d, 4s and 4p orbitals and the cage π orbitals. The magnetic moment of the endohedrally doped TM atoms in the Mg12O12 are preserved to some extent due to the interaction between the TM and Mg12O12 nanocage, in contrast to the completely quenched magnetic moment of the Fe and Ni atoms in the Mg11(TM)O12 complexes. Furthermore, charge population analysis shows that charge transfer occurs from TM atom to the cage for endohedrally and substitutionally doping.
Assembling nitrogen and oxygen co-doped graphene quantum dots onto hierarchical carbon networks for all-solid-state flexible supercapacitors

International Nuclear Information System (INIS)

Li, Zhen; Li, Yanfeng; Wang, Liang; Cao, Ling; Liu, Xiang; Chen, Zhiwen; Pan, Dengyu; Wu, Minghong

2017-01-01

Highlights: • The all-carbon ternary flexible electrodes have been fabricated by the electrode deposition of nitrogen and oxygen co-doped single-crystalline GQDs. • The flexible electrodes deliver ultrahigh specific capacitance (461 mF cm"−"2) by inducing a high concentration of active nitrogen and oxygen at edge. • Symmetrical N-O-GQD/CNT/CC all-solid-state flexible supercapacitors offer energy density up to 32 μWh cm"−"2 and demonstrate the good stability, high flexibility, and folding ability under different deformations. • Nitrogen and oxygen co-doped GQDs can function as a highly active, solution-processable pseudocapacitive materials applicable to high-performance supercapacitors. - Abstract: We present a novel approach for hierarchical fabrication of high-performance, all-solid-state, flexible supercapacitors from environmentally friendly all-carbon materials. Three-dimensional carbon nanotube/carbon cloth network (CNT/CC) is used as a conductive, flexible and free-standing scaffold for the electro-deposition of highly N/O co-doped graphene quantum dots to form the high-activity, all-carbon electrodes. The hierarchical structure of the CNT/CC network with high electrical conductivity and high surface area provides improved conductive pathways for the efficient activation of GQDs with high pseudocapacitance and electrical double layer capacitance. The obtained N-O-GQD/CNT/CC electrodes for all-solid-state flexible supercapacitors exhibit an ultrahigh areal capacitance of up to 461 mF cm"−"2 at a current density of 0.5 mA cm"−"2, while keeping high rate and cyclic performances. This work highlights the great potential of highly active GQDs in the construction of high-performance flexible energy-storage devices.
Enhanced performance of proton exchange membrane fuel cell by introducing nitrogen-doped CNTs in both catalyst layer and gas diffusion layer

CSIR Research Space (South Africa)

Hou, S

2017-11-01

Full Text Available The performance of the proton exchange membrane fuel cell (PEMFC) is significantly improved through introducing nitrogen-doped carbon nanotubes (NCNTs) into the catalyst layer (CL) and microporous layer (MPL) of the membrane electrode assembly (MEA...
Probing the interaction of noble gases with pristine and nitrogen-doped graphene through Raman spectroscopy

Science.gov (United States)

Cunha, Renato; Perea-López, Néstor; Elías, Ana Laura; Fujisawa, Kazunori; Carozo, Victor; Feng, Simin; Lv, Ruitao; dos Santos, Maria Cristina; Terrones, Mauricio; Araujo, Paulo T.

2018-05-01

The interactions of adsorbates with graphene have received increasing attention due to its importance in the development of applications involving graphene-based coatings. Here, we present a study of the adsorption of noble gases on pristine and nitrogen-doped graphene. Single-layer graphene samples were synthesized by chemical vapor deposition (CVD) and transferred to transmission electron microscopy (TEM) grids. Several noble gases were allowed to adsorb on the suspended graphene substrate at very low temperatures. Raman spectra show distinct frequency blue shifts in both the 2D and G bands, which are induced by gas adsorption onto high quality single layer graphene (1LG). These shifts, which we associate with compressive biaxial strain in the graphene layers induced by the noble gases, are negligible for nitrogen-doped graphene. Additionally, a thermal depinning transition, which is related to the desorption of a noble gas layer from the graphene surface at low temperatures (ranging from 20 to 35 K), was also observed at different transition temperatures for different noble gases. These transition temperatures were found to be 25 K for argon and 35 K for xenon. Moreover, we were able to obtain values for the compressive biaxial strain in graphene induced by the adsorbed layer of noble gases, using Raman spectroscopy. Ab initio calculations confirmed the correlation between the noble gas-induced strain and the changes in the Raman features observed.
Adsorption of CH{sub 4} on nitrogen- and boron-containing carbon models of coal predicted by density-functional theory

Energy Technology Data Exchange (ETDEWEB)

Liu, Xiao-Qiang [College of Chemistry, Key Lab of Green Chemistry and Technology in Ministry of Education, Sichuan University, Chengdu 610064 (China); Xue, Ying, E-mail: yxue@scu.edu.cn [College of Chemistry, Key Lab of Green Chemistry and Technology in Ministry of Education, Sichuan University, Chengdu 610064 (China); Tian, Zhi-Yue; Mo, Jing-Jing; Qiu, Nian-Xiang [College of Chemistry, Key Lab of Green Chemistry and Technology in Ministry of Education, Sichuan University, Chengdu 610064 (China); Chu, Wei [Department of Chemical Engineering, Sichuan University, Chengdu 610065 (China); Xie, He-Ping [Key Laboratory of Energy Engineering Safety and Mechanics on Disasters, The Ministry of Education, Sichuan University, Chengdu 610065 (China)

2013-11-15

Graphene doped by nitrogen (N) and/or boron (B) is used to represent the surface models of coal with the structural heterogeneity. Through the density functional theory (DFT) calculations, the interactions between coalbed methane (CBM) and coal surfaces have been investigated. Several adsorption sites and orientations of methane (CH{sub 4}) on graphenes were systematically considered. Our calculations predicted adsorption energies of CH{sub 4} on graphenes of up to −0.179 eV, with the strongest binding mode in which three hydrogen atoms of CH{sub 4} direct to graphene surface, observed for N-doped graphene, compared to the perfect (−0.154 eV), B-doped (−0.150 eV), and NB-doped graphenes (−0.170 eV). Doping N in graphene increases the adsorption energies of CH{sub 4}, but slightly reduced binding is found when graphene is doped by B. Our results indicate that all of graphenes act as the role of a weak electron acceptor with respect to CH{sub 4}. The interactions between CH{sub 4} and graphenes are the physical adsorption and slightly depend upon the adsorption sites on graphenes and the orientations of methane as well as the electronegativity of dopant atoms in graphene.
In Situ Activation of Nitrogen-Doped Graphene Anchored on Graphite Foam for a High-Capacity Anode.

Science.gov (United States)

Ji, Junyi; Liu, Jilei; Lai, Linfei; Zhao, Xin; Zhen, Yongda; Lin, Jianyi; Zhu, Yanwu; Ji, Hengxing; Zhang, Li Li; Ruoff, Rodney S

2015-08-25

We report the fabrication of a three-dimensional free-standing nitrogen-doped porous graphene/graphite foam by in situ activation of nitrogen-doped graphene on highly conductive graphite foam (GF). After in situ activation, intimate "sheet contact" was observed between the graphene sheets and the GF. The sheet contact produced by in situ activation is found to be superior to the "point contact" obtained by the traditional drop-casting method and facilitates electron transfer. Due to the intimate contact as well as the use of an ultralight GF current collector, the composite electrode delivers a gravimetric capacity of 642 mAh g(-1) and a volumetric capacity of 602 mAh cm(-3) with respect to the whole electrode mass and volume (including the active materials and the GF current collector). When normalized based on the mass of the active material, the composite electrode delivers a high specific capacity of up to 1687 mAh g(-1), which is superior to that of most graphene-based electrodes. Also, after ∼90 s charging, the anode delivers a capacity of about 100 mAh g(-1) (with respect to the total mass of the electrode), indicating its potential use in high-rate lithium-ion batteries.
Hetero-atom doped carbon nanotubes for dye degradation and oxygen reduction reaction

Energy Technology Data Exchange (ETDEWEB)

Nandan, Ravi, E-mail: aerawat27@gmail.com; Nanda, Karuna Kar [Materials Research Centre, Indian Institute of Science, Bangalore-560012 (India)

2015-06-24

We report the synthesis of nitrogen doped vertically aligned multi-walled (MWNCNTs) carbon nanotubes by pyrolysis and its catalytic performance for degradation of methylene blue (MB) dye & oxygen reduction reaction (ORR). The degradation of MB was monitored spectrophotometrically with time. Kinetic studies show the degradation of MB follows a first order kinetic with rate constant k=0.0178 min{sup −1}. The present rate constant is better than that reported for various supported/non-supported semiconducting nanomaterials. Further ORR performance in alkaline media makes MWNCNTs a promising cost-effective, fuel crossover tolerance, metal-free, eco-friendly cathode catalyst for direct alcohol fuel cell.
A new approach to the preparation of nitrogen-doped titania visible light photocatalyst

KAUST Repository

Kachina, Anna

2012-02-28

A new simple method is described, allowing introduction of nitrogen into the TiO 2 lattice at low temperatures. The technique is based on the introduction of oxophilic molecules, such as CCl 4, into the reaction mixture. The treatment of titanium dioxide powders by NH 3-CCl 4 mixtures leads to highly dispersed N-doped TiO 2. As compared to bare TiO 2 or to the same oxide treated with sole NH 3, the solids treated with NH 3-CCl 4 mixtures showed a stronger red shift in optical absorption and enhanced photocatalytic activity under visible light, as demonstrated for two reactions of formic acid oxidation and photocatalytic production of hydrogen from methanol. The nitridation temperature can be significantly decreased by introducing CCl 4, because of a favorable change of the reaction thermodynamics. Not only can higher specific surface area of materials be obtained as a result of avoiding sintering but a higher amount of nitrogen is introduced in a position beneficial for the enhanced catalytic activity. The X-ray photoelectron spectroscopy study demonstrated increased surface concentration of nitrogen having N 1s binding energy near 399 eV. As established by ESR, the nature of paramagnetic species generated by treatments is strongly dependent on the titania polymorph variety and crystallinity as well as on the treatment conditions, but in all cases the major part of introduced nitrogen remains ESR-silent. © 2012 American Chemical Society.
Iron, nitrogen and silicon doped diamond like carbon (DLC) thin films: A comparative study

Energy Technology Data Exchange (ETDEWEB)

Ray, Sekhar C., E-mail: Raysc@unisa.ac.za [Department of Physics, College of Science, Engineering and Technology, University of South Africa, Private Bag X6, Florida, 1710, Science Campus, Christiaan de Wet and Pioneer Avenue, Florida Park, Johannesburg (South Africa); Pong, W.F. [Department of Physics, Tamkang University, Tamsui 251, New Taipei City, Taiwan (China); Papakonstantinou, P. [Nanotechnology and Integrated Bio-Engineering Centre, University of Ulster, Shore Road, Newtownabbey BT37 0QB (United Kingdom)

2016-07-01

The X-ray absorption near edge structure (XANES), X-ray photoelectron spectroscopy (XPS), valence band photoemission (VB-PES) and Raman spectroscopy results show that the incorporation of nitrogen in pulsed laser deposited diamond like carbon (DLC) thin films, reverts the sp{sup 3} network to sp{sup 2} as evidenced by an increase of the sp{sup 2} cluster and I{sub D}/I{sub G} ratio in C K-edge XANES and Raman spectra respectively which reduces the hardness/Young's modulus into the film network. Si-doped DLC film deposited in a plasma enhanced chemical vapour deposition process reduces the sp{sup 2} cluster and I{sub D}/I{sub G} ratio that causes the decrease of hardness/Young's modulus of the film structure. The Fe-doped DLC films deposited by dip coating technique increase the hardness/Young's modulus with an increase of sp{sup 3}-content in DLC film structure. - Highlights: • Fe, N and Si doped DLC films deposited by dip, PLD and PECVD methods respectively • DLC:Fe thin films have higher hardness/Young's modulus than DLC:N(:Si) thin films. • sp{sup 3} and sp{sup 2} contents are estimated from C K-edge XANES and VB-PES measurements.
Atomic Origins of Monoclinic-Tetragonal (Rutile) Phase Transition in Doped VO 2 Nanowires

KAUST Repository

Asayesh-Ardakani, Hasti

2015-10-12

There has been long-standing interest in tuning the metal-insulator phase transition in vanadium dioxide (VO) via the addition of chemical dopants. However, the underlying mechanisms by which doping elements regulate the phase transition in VO are poorly understood. Taking advantage of aberration-corrected scanning transmission electron microscopy, we reveal the atomistic origins by which tungsten (W) dopants influence the phase transition in single crystalline WVO nanowires. Our atomically resolved strain maps clearly show the localized strain normal to the (122¯) lattice planes of the low W-doped monoclinic structure (insulator). These strain maps demonstrate how anisotropic localized stress created by dopants in the monoclinic structure accelerates the phase transition and lead to relaxation of structure in tetragonal form. In contrast, the strain distribution in the high W-doped VO structure is relatively uniform as a result of transition to tetragonal (metallic) phase. The directional strain gradients are furthermore corroborated by density functional theory calculations that show the energetic consequences of distortions to the local structure. These findings pave the roadmap for lattice-stress engineering of the MIT behavior in strongly correlated materials for specific applications such as ultrafast electronic switches and electro-optical sensors.

Atomic Origins of Monoclinic-Tetragonal (Rutile) Phase Transition in Doped VO 2 Nanowires

KAUST Repository

Asayesh-Ardakani, Hasti; Nie, Anmin; Marley, Peter M.; Zhu, Yihan; Phillips, Patrick J.; Singh, Sujay; Mashayek, Farzad; Sambandamurthy, Ganapathy; Low, Ke Bin; Klie, Robert F.; Banerjee, Sarbajit; Odegard, Gregory M.; Shahbazian-Yassar, Reza

2015-01-01

There has been long-standing interest in tuning the metal-insulator phase transition in vanadium dioxide (VO) via the addition of chemical dopants. However, the underlying mechanisms by which doping elements regulate the phase transition in VO are poorly understood. Taking advantage of aberration-corrected scanning transmission electron microscopy, we reveal the atomistic origins by which tungsten (W) dopants influence the phase transition in single crystalline WVO nanowires. Our atomically resolved strain maps clearly show the localized strain normal to the (122¯) lattice planes of the low W-doped monoclinic structure (insulator). These strain maps demonstrate how anisotropic localized stress created by dopants in the monoclinic structure accelerates the phase transition and lead to relaxation of structure in tetragonal form. In contrast, the strain distribution in the high W-doped VO structure is relatively uniform as a result of transition to tetragonal (metallic) phase. The directional strain gradients are furthermore corroborated by density functional theory calculations that show the energetic consequences of distortions to the local structure. These findings pave the roadmap for lattice-stress engineering of the MIT behavior in strongly correlated materials for specific applications such as ultrafast electronic switches and electro-optical sensors.
Nitrogen-Doped Nanoporous Carbon Membranes with Co/CoP Janus-Type Nanocrystals as Hydrogen Evolution Electrode in Both Acidic and Alkaline Environments

KAUST Repository

Wang, Hong; Min, Shixiong; Wang, Qiang; Li, Debao; Casillas, Gilberto; Ma, Chun; Li, Yangyang; Liu, Zhixiong; Li, Lain-Jong; Yuan, Jiayin; Antonietti, Markus; Wu, Tao

2017-01-01

reaction (HER). Benefited from multiple structural merits, such as a high degree of graphitization, three-dimensionally interconnected micro/meso/macropores, uniform nitrogen doping, well-dispersed Co/CoP nanocrystals, as well as the confinement effect
"Doping" pentacene with sp(2)-phosphorus atoms: towards high performance ambipolar semiconductors.

Science.gov (United States)

Long, Guankui; Yang, Xuan; Chen, Wangqiao; Zhang, Mingtao; Zhao, Yang; Chen, Yongsheng; Zhang, Qichun

2016-01-28

Recent research progress in black phosphorus sheets strongly encourages us to employ pentacene as a parent system to systematically investigate how the "doping" of sp(2)-phosphorus atoms onto the backbone of pentacene influences its optical and charge transport properties. Our theoretical investigations proved that increasing the contribution of the pz atomic orbital of the sp(2)-phosphorus to the frontier molecular orbital of phosphapentacenes could significantly decrease both hole and electron reorganization energies and dramatically red-shift the absorption of pentacene. The record smallest hole and electron reorganization energies of 69.80 and 95.74 meV for heteropentacene derivatives were obtained. These results suggest that phosphapentacenes (or phosphaacenes) could be potential promising candidates to achieve both higher and balanced mobilities in organic field effect transistors and realize a better power conversion efficiency in organic photovoltaics.
Thermal spin filtering effect and giant magnetoresistance of half-metallic graphene nanoribbon co-doped with non-metallic Nitrogen and Boron

Science.gov (United States)

Huang, Hai; Zheng, Anmin; Gao, Guoying; Yao, Kailun

2018-03-01

Ab initio calculations based on density functional theory and non-equilibrium Green's function are performed to investigate the thermal spin transport properties of single-hydrogen-saturated zigzag graphene nanoribbon co-doped with non-metallic Nitrogen and Boron in parallel and anti-parallel spin configurations. The results show that the doped graphene nanoribbon is a full half-metal. The two-probe system based on the doped graphene nanoribbon exhibits various excellent spin transport properties, including the spin-filtering effect, the spin Seebeck effect, the single-spin negative differential thermal resistance effect and the sign-reversible giant magnetoresistance feature. Excellently, the spin-filtering efficiency can reach nearly 100% in the parallel configuration and the magnetoresistance ratio can be up to -1.5 × 1010% by modulating the electrode temperature and temperature gradient. Our findings indicate that the metal-free doped graphene nanoribbon would be a promising candidate for spin caloritronic applications.
Does the position of the electron-donating nitrogen atom in the ring system influence the efficiency of a dye-sensitized solar cell? A computational study.

Science.gov (United States)

Biswas, Abul Kalam; Barik, Sunirmal; Das, Amitava; Ganguly, Bishwajit

2016-06-01

We have reported a number of new metal-free organic dyes (2-6) that have cyclic asymmetric benzotripyrrole derivatives as donor groups with peripheral nitrogen atoms in the ring, fluorine and thiophene groups as π-spacers, and a cyanoacrylic acid acceptor group. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were employed to examine the influence of the position of the donor nitrogen atom and π-conjugation on solar cell performance. The calculated electron-injection driving force (ΔG inject), electron-regeneration driving force (ΔG regen), light-harvesting efficiency (LHE), dipole moment (μ normal), and number of electrons transferred (∆q) indicate that dyes 3, 4, and 6 have significantly higher efficiencies than reference dye 1, which exhibits high efficiency. We also extended our comparison to some other reported dyes, 7-9, which have a donor nitrogen atom in the middle of the ring system. The computed results suggest that dye 6 possesses a higher incident photon to current conversion efficiency (IPCE) than reported dyes 7-9. Thus, the use of donor groups with peripheral nitrogen atoms appears to lead to more efficient dyes than those in which the nitrogen atom is present in the middle of the donor ring system. Graphical Abstract The locations of the nitrogen atoms in the donor groups in the designed dye molecules have an important influence on DSSC efficiency.
Doping of ZnO nanowires using phosphorus diffusion from a spin-on doped glass source

International Nuclear Information System (INIS)

Bocheux, A.; Robin, I. C.; Bonaimé, J.; Hyot, B.; Feuillet, G.; Kolobov, A. V.; Fons, P.; Mitrofanov, K. V.; Tominaga, J.; Tamenori, Y.

2014-01-01

In this article, we report on ZnO nanowires that were phosphorus doped using a spin on dopant glass deposition and diffusion method. Photoluminescence measurements suggest that this process yields p-doped ZnO. The spatial location of P atoms was studied using x-ray near-edge absorption structure spectroscopy and it is concluded that the doping is amphoteric with P atoms located on both Zn and O sites
Nitrogen doped silicon-carbon multilayer protective coatings on carbon obtained by thermionic vacuum arc (TVA) method

Science.gov (United States)

Ciupinǎ, Victor; Vasile, Eugeniu; Porosnicu, Corneliu; Vladoiu, Rodica; Mandes, Aurelia; Dinca, Virginia; Nicolescu, Virginia; Manu, Radu; Dinca, Paul; Zaharia, Agripina

2018-02-01

To obtain protective nitrogen doped Si-C multilayer coatings on carbon, used to improve the oxidation resistance of carbon, was used TVA method. The initial carbon layer has been deposed on a silicon substrate in the absence of nitrogen, and then a 3nm Si thin film to cover carbon layer was deposed. Further, seven Si and C layers were alternatively deposed in the presence of nitrogen ions. In order to form silicon carbide at the interface between silicon and carbon layers, all carbon, silicon and nitrogen ions energy has increased up to 150eV. The characterization of microstructure and electrical properties of as-prepared N-Si-C multilayer structures were done using Transmission Electron Microscopy (TEM, STEM) techniques, Thermal Desorption Spectroscopy (TDS) and electrical measurements. The retention of oxygen in the protective layer of N-Si-C is due to the following phenomena: (a) The reaction between oxygen and silicon carbide resulting in silicon oxide and carbon dioxide; (b) The reaction involving oxygen, nitrogen and silicon resulting silicon oxinitride with a variable composition; (c) Nitrogen acts as a trapping barrier for oxygen. To perform electrical measurements, ohmic contacts were attached on the N-Si-C samples. Electrical conductivity was measured in constant current mode. To explain the temperature behavior of electrical conductivity we assumed a thermally activated electric transport mechanism.
Preparation of nitrogen-doped cotton stalk microporous activated carbon fiber electrodes with different surface area from hexamethylenetetramine-modified cotton stalk for electrochemical degradation of methylene blue

Directory of Open Access Journals (Sweden)

Kunquan Li

Full Text Available Cotton-stalk activated carbon fibers (CSCFs with controllable micropore area and nitrogen content were prepared as an efficient electrode from hexamethylenetetramine-modified cotton stalk by steam/ammonia activation. The influence of microporous area, nitrogen content, voltage and initial concentration on the electrical degradation efficiency of methylene blue (MB was evaluated by using CSCFs as anode. Results showed that the CSCF electrodes exhibited excellent MB electrochemical degradation ability including decolorization and COD removal. Increasing micropore surface area and nitrogen content of CSCF anode leaded to a corresponding increase in MB removal. The prepared CSCF-800-15-N, which has highest N content but lowest microporous area, attained the best degradation effect with 97% MB decolorization ratio for 5 mg/L MB at 12 V in 4 h, implying the doped nitrogen played a prominent role in improving the electrochemical degradation ability. The electrical degradation reaction was well described by first-order kinetics model. Overall, the aforesaid findings suggested that the nitrogen-doped CSCFs were potential electrode materials, and their electrical degradation abilities could be effectively enhanced by controlling the nitrogen content and micropore surface area. Keywords: Cotton stalk, Nitrogen content, Electrode, Surface area, Methylene blue
Plasma enhanced atomic layer batch processing of aluminum doped titanium dioxide

International Nuclear Information System (INIS)

Lehnert, Wolfgang; Ruhl, Guenther; Gschwandtner, Alexander

2012-01-01

Among many promising high-k dielectrics, TiO 2 is an interesting candidate because of its relatively high k value of over 40 and its easy integration into existing semiconductor manufacturing schemes. The most critical issues of TiO 2 are its low electrical stability and its high leakage current density. However, doping TiO 2 with Al has shown to yield significant improvement of layer quality on Ru electrodes [S. K. Kim et al., Adv. Mater. 20, 1429 (2008)]. In this work we investigated if atomic layer deposition (ALD) of Al doped TiO 2 is feasible in a batch system. Electrical characterizations were done using common electrode materials like TiN, TaN, or W. Additionally, the effect of plasma enhanced processing in this reactor was studied. For this investigation a production batch ALD furnace has been retrofitted with a plasma source which can be used for post deposition anneals with oxygen radicals as well as for directly plasma enhanced ALD. After evaluation of several Ti precursors a deposition process for AlTiO x with excellent film thickness and composition uniformity was developed. The effects of post deposition anneals, Al 2 O 3 interlayers between electrode and TiO 2 , Al doping concentration, plasma enhanced deposition and electrode material type on leakage current density are shown. An optimized AlTiO x deposition process on TaN electrodes yields to leakage current density of 5 x 10 -7 A/cm 2 at 2 V and k values of about 35. Thus, it could be demonstrated that a plasma enhanced batch ALD process for Al doped TiO 2 is feasible with acceptable leakage current density on a standard electrode material.
Nitrogen-Doped Hollow Carbon Spheres with Embedded Co Nanoparticles as Active Non-Noble-Metal Electrocatalysts for the Oxygen Reduction Reaction

Directory of Open Access Journals (Sweden)

Ruohao Xing

2018-02-01

Full Text Available Transition metal (Fe, Co, Ni complexes on carbon nanomaterials are promising candidates as electrocatalysts towards the oxygen reduction reaction (ORR. In this paper, nitrogen-doped hollow carbon spheres with embedded Co nanoparticles were successfully prepared via a controllable synthesis strategy. The morphology characterization shows that the hollow carbon spheres possess an average diameter of ~150 nm with a narrow size distribution and a shell thickness of ~14.5 nm. The content of N doping ranges from 2.1 to 6.6 at.% depending on the calcination temperature from 900 to 1050 °C. Compared with commercial Pt/C, the Co-containing nitrogen-doped hollow carbon spheres prepared at 900 °C (CoNHCS-900 as an ORR electrocatalyst shows a half-wave potential shift of only ∆E1/2 = 55 mV, but a superior stability of about 90.2% maintenance after 20,000 s in the O2-saturated 0.1 M KOH at a rotating speed of 1600 rpm. This could be ascribed to the synergistic effects of N-containing moieties, Co-Nx species, and Co nanoparticles, which significantly increase the density of active sites and promote the charge transfer during the ORR process.
3D analysis of the morphology and spatial distribution of nitrogen in nitrogen-doped carbon nanotubes by energy-filtered transmission electron microscopy tomography.

Science.gov (United States)

Florea, Ileana; Ersen, Ovidiu; Arenal, Raul; Ihiawakrim, Dris; Messaoudi, Cédric; Chizari, Kambiz; Janowska, Izabela; Pham-Huu, Cuong

2012-06-13

We present here the application of the energy-filtered transmission electron microscopy (EFTEM) in the tomographic mode to determine the precise 3D distribution of nitrogen within nitrogen-doped carbon nanotubes (N-CNTs). Several tilt series of energy-filtered images were acquired on the K ionization edges of carbon and nitrogen on a multiwalled N-CNT containing a high amount of nitrogen. Two tilt series of carbon and nitrogen 2D maps were then calculated from the corresponding energy-filtered images by using a proper extraction procedure of the chemical signals. Applying iterative reconstruction algorithms provided two spatially correlated C and N elemental-selective volumes, which were then simultaneously analyzed with the shape-sensitive reconstruction deduced from Zero-Loss recordings. With respect to the previous findings, crucial information obtained by analyzing the 3D chemical maps was that, among the two different kind of arches formed in these nanotubes (transversal or rounded ones depending on their morphology), the transversal arches contain more nitrogen than do the round ones. In addition, a detailed analysis of the shape-sensitive volume allowed the observation of an unexpected change in morphology along the tube axis: close to the round arches (with less N), the tube is roughly cylindrical, whereas near the transversal ones (with more N), its shape changes to a prism. This relatively new technique is very powerful in the material science because it combines the ability of the classical electron tomography to solve 3D structures and the chemical selectivity of the EFTEM imaging.
Facile Synthesis of Nitrogen-doped Carbon Quantum Dots for Bio-imaging

Directory of Open Access Journals (Sweden)

de Yro Persia Ada N.

2016-01-01

Full Text Available Carbon quantum dots (CQD with fascinating properties has gradually become a rising star as a new nanocarbon member due to its nonthreatening, abundant and inexpensive nature. This study reports on a facile preparation of fluorescent carbon quantum dots (CQD from iota Carrageenan. CQD from iota Carrageenan was produced by hydrothermal method with a quantum yield (QY of 16 to 20%. Doping the CQD with nitrogen by the addition of tetraethylene pentamine (TEPE produced CQD with a QY of 77%. FTIR data confirmed the formation of hydroxyl, carboxylic and carbonyl functional groups as confirmed by the ToFSIMS data due to the presence of nitrogen bonds on the N-CQD produced with TEPE. The CQD and N-CQD produced are crystalline with graphitic structures because of the presence of sp2 graphitic d line spacing with the sizes ranging from 2 to 10nm. To examine the feasibility of using the CQD as nanoprobe in practical applications, labelling and detection of E.coli was performed. The E.coli fluoresced proving CQD as an effective probe in bio imaging application. This study has successfully demonstrated a facile approach of producing CQD with significant high quantum yields to fluorescent CQD for bio imaging applications.
Strain induced atomic structure at the Ir-doped LaAlO3/SrTiO3 interface.

Science.gov (United States)

Lee, M; Arras, R; Warot-Fonrose, B; Hungria, T; Lippmaa, M; Daimon, H; Casanove, M J

2017-11-01

The structure of Ir-doped LaAlO 3 /SrTiO 3 (001) interfaces was investigated on the atomic scale using probe-corrected transmission electron microscopy in high-angle annular dark-field scanning mode (HAADF-STEM) and electron energy loss spectroscopy (EELS), combined with first-principles calculations. We report the evolution of the strain state experimentally measured in a 5 unit-cell thick LaAlO 3 film as a function of the Ir concentration in the topmost SrTiO 3 layer. It is shown that the LaAlO 3 layers remain fully elastically strained up to 3% of Ir doping, whereas a higher doping level seems to promote strain relaxation through enhanced cationic interdiffusion. The observed differences between the energy loss near edge structure (ELNES) of Ti-L 2,3 and O-K edges at non-doped and Ir-doped interfaces are consistent with the location of the Ir dopants at the interface, up to 3% of Ir doping. These findings, supported by the results of density functional theory (DFT) calculations, provide strong evidence that the effect of dopant concentrations on the properties of this kind of interface should not be analyzed without obtaining essential information from the fine structural and chemical analysis of the grown structures.
Density functional investigation of mercury and arsenic adsorption on nitrogen doped graphene decorated with palladium clusters: A promising heavy metal sensing material in farmland

Energy Technology Data Exchange (ETDEWEB)

Zhao, Chunjiang, E-mail: zhaocj_nercita@163.com [National Engineering Research Center for Information Technology in Agriculture, Beijing 100097 (China); Beijing Research Center for Information Technology in Agriculture, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097 (China); Key Laboratory for Information Technologies in Agriculture, Ministry of Agriculture, Beijing100097 (China); Wu, Huarui, E-mail: wuhrnercita@163.com [National Engineering Research Center for Information Technology in Agriculture, Beijing 100097 (China); Beijing Research Center for Information Technology in Agriculture, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097 (China); Key Laboratory for Information Technologies in Agriculture, Ministry of Agriculture, Beijing100097 (China)

2017-03-31

Highlights: • PNG can be acted as micro-sensor for monitoring heavy metal in agriculture. • The most favorable adsorption site of Pd atom or cluster on PNG is the vacancy site. • The Pd atom or cluster enhance the reactivity of PNG toward Hg and AsH{sub 3} adsorption. • The efficiency of a sorbent can be tuned by tailoring the ε{sub d} of adsorbed metals. - Abstract: Density functional theory calculations are carried out to study the adsorption of mercury and arsenic on Pd{sub n} (n = 1–6) supported on pyridine-like nitrogen doped graphene (PNG). Owing to the promising sensitivity in trace amounts of atoms or molecules, PNG can be acted as micro-sensor for sensing heavy metals in agriculture soils. Through the analyses of structural and electronic properties of pristine PNG and Pd atom decorated PNG, we find that the most favorable adsorption site for Pd atom is the vacancy site. The analyses of structural and electronic properties reveal that the Pd atom or clusters can enhance the reactivity for Hg and AsH{sub 3} adsorption on PNG. The adsorption ability of Hg on Pd{sub n} decorated PNG is found to be related to the d-band center (ε{sub d}) of the Pd{sub n}, in which the closer ε{sub d} of Pd{sub n} to the Fermi level, the higher adsorption strength for Hg on Pd{sub n} decorated PNG. Moreover, the charge transfer between Pd{sub n} and arsenic may constitute arsenic adsorption on Pd{sub n} decorated PNG. Further design of highly efficient carbon based sorbents for heavy metals removal should be focused on tailoring ε{sub d} of adsorbed metals.
Utilization of an arc-heated jet for production of supersonic seeded beams of atomic nitrogen

International Nuclear Information System (INIS)

Bickes, R.W. Jr.; Newton, K.R.; Herrmann, J.M.; Bernstein, R.B.

1976-01-01

Intense supersonic beams of atomic nitrogen (>10 17 atoms sr -1 sec -1 ) have been produced from the dissociation of N 2 in an Ar arc (at temperatures in excess of 6000 K) using the arc-heated nozzle beam source of Young, Rodgers, and Knuth. Experiments characterizing the N 2 dissociation and the translational energies of the N, N 2 , and Ar components in the beams are described. Evidence is presented for the formation of atomic C as well as C 2 and CH from the pyrolysis of CH 4 and C 2 H 4 in the Ar arc
Platinum-TM (TM = Fe, Co) alloy nanoparticles dispersed nitrogen doped (reduced graphene oxide-multiwalled carbon nanotube) hybrid structure cathode electrocatalysts for high performance PEMFC applications.

Science.gov (United States)

Vinayan, B P; Ramaprabhu, S

2013-06-07

The efforts to push proton exchange membrane fuel cells (PEMFC) for commercial applications are being undertaken globally. In PEMFC, the sluggish kinetics of oxygen reduction reactions (ORR) at the cathode can be improved by the alloying of platinum with 3d-transition metals (TM = Fe, Co, etc.) and with nitrogen doping, and in the present work we have combined both of these aspects. We describe a facile method for the synthesis of a nitrogen doped (reduced graphene oxide (rGO)-multiwalled carbon nanotubes (MWNTs)) hybrid structure (N-(G-MWNTs)) by the uniform coating of a nitrogen containing polymer over the surface of the hybrid structure (positively surface charged rGO-negatively surface charged MWNTs) followed by the pyrolysis of these (rGO-MWNTs) hybrid structure-polymer composites. The N-(G-MWNTs) hybrid structure is used as a catalyst support for the dispersion of platinum (Pt), platinum-iron (Pt3Fe) and platinum-cobalt (Pt3Co) alloy nanoparticles. The PEMFC performances of Pt-TM alloy nanoparticle dispersed N-(G-MWNTs) hybrid structure electrocatalysts are 5.0 times higher than that of commercial Pt-C electrocatalysts along with very good stability under acidic environment conditions. This work demonstrates a considerable improvement in performance compared to existing cathode electrocatalysts being used in PEMFC and can be extended to the synthesis of metal, metal oxides or metal alloy nanoparticle decorated nitrogen doped carbon nanostructures for various electrochemical energy applications.
Functionalization of silicon-doped single walled carbon nanotubes at the doping site: An ab initio study

International Nuclear Information System (INIS)

Song Chen; Xia Yueyuan; Zhao Mingwen; Liu Xiangdong; Li Feng; Huang Boda; Zhang Hongyu; Zhang Bingyun

2006-01-01

We performed ab initio calculations on the cytosine-functionalized silicon-doped single walled carbon nanotubes (SWNT). The results show that silicon substitutional doping to SWNT can dramatically change the atomic and electronic structures of the SWNT. And more importantly, it may provide an efficient pathway for further sidewall functionalization to synthesize more complicated SWNT based complex materials, for example, our previously proposed base-functionalized SWNTs, because the doping silicon atom can improve the reaction activity of the tube at the doping site due to its preference to form sp3 hybridization bonding
DFT study of Al doped armchair SWCNTs

Energy Technology Data Exchange (ETDEWEB)

Dhiman, Shobhna, E-mail: s-dhiman@hotmail.com [Department of Applied Science, PEC, University of Technology, Chandigarh -160012 (India); Rani, Anita [Guru Nanak College for Girls, Sri Muktsar Sahib, Punjab-152026 (India); Kumar, Ranjan; Dharamvir, Keya [Department of Physics, Panjab University, Chandigarh-160014 (India)

2016-05-23

Electronic properties of endohedrally doped armchair single-walled carbon nanotubes (SWCNTs) with a chain of six Al atoms have been studied using ab-initio density functional theory. We investigate the binding energy/atom, ionization potential, electron Affinity and Homo-Lumo gap of doped armchair SWNTs from (4,4) to (6,6) with two ends open. BE/dopant atom and ionization potential is maximum for (6, 6) doped armchair carbon nanotube; suggest that it is more stable than (4, 4) and (5, 5) doped tubes. HOMO - LUMO gap of Al doped arm chair carbon nanotubes decreases linearly with the increase in diameter of the tube. This shows that confinement induce a strong effect on electronic properties of doped tubes. These combined systems can be used for future nano electronics. The ab–initio calculations were performed with SIESTA code using generalized gradient approximation (GGA).
Effects of ultraviolet light on B-doped CdS thin films prepared by spray pyrolysis method using perfume atomizer

Science.gov (United States)

Novruzov, V. D.; Keskenler, E. F.; Tomakin, M.; Kahraman, S.; Gorur, O.

2013-09-01

Boron doped CdS thin films were deposited by spray pyrolysis method using perfume atomizer. The effects of ultraviolet light on the structural, optical and electrical properties of B-doped CdS thin films were investigated as a function of dopant concentration (B/Cd). X-ray diffraction studies showed that all samples were polycrystalline nature with hexagonal structure. It was determined that the preferred orientation of non-illuminated samples changes from (1 0 1) to (0 0 2) with B concentration. The c lattice constant of films decreases from 6.810 Å to 6.661 Å with boron doping. The XRD peak intensity increased with the illumination for almost all the samples. The lattice parameters of B-doped samples remained nearly constant after illumination. It was found that the optical transmittance, photoluminescence spectra, resistivity and carrier concentration of the B-doped samples are stable after the illumination with UV light. Also the effects of UV light on B-doped CdS/Cu2S solar cell were investigated and it was determined that photoelectrical parameters of B-doped solar cell were more durable against the UV light.
Effects of ultraviolet light on B-doped CdS thin films prepared by spray pyrolysis method using perfume atomizer

Energy Technology Data Exchange (ETDEWEB)

Novruzov, V.D. [Department of Physics, Recep Tayyip Erdogan University, Rize (Turkey); Keskenler, E.F., E-mail: keskenler@gmail.com [Department of Nanotechnology Engineering, Recep Tayyip Erdogan University, Rize (Turkey); Tomakin, M. [Department of Physics, Recep Tayyip Erdogan University, Rize (Turkey); Kahraman, S. [Department of Physics, Mustafa Kemal University, Hatay (Turkey); Gorur, O. [Department of Physics, Abant Izzet Baysal University, Bolu (Turkey)

2013-09-01

Boron doped CdS thin films were deposited by spray pyrolysis method using perfume atomizer. The effects of ultraviolet light on the structural, optical and electrical properties of B-doped CdS thin films were investigated as a function of dopant concentration (B/Cd). X-ray diffraction studies showed that all samples were polycrystalline nature with hexagonal structure. It was determined that the preferred orientation of non-illuminated samples changes from (1 0 1) to (0 0 2) with B concentration. The c lattice constant of films decreases from 6.810 Å to 6.661 Å with boron doping. The XRD peak intensity increased with the illumination for almost all the samples. The lattice parameters of B-doped samples remained nearly constant after illumination. It was found that the optical transmittance, photoluminescence spectra, resistivity and carrier concentration of the B-doped samples are stable after the illumination with UV light. Also the effects of UV light on B-doped CdS/Cu{sub 2}S solar cell were investigated and it was determined that photoelectrical parameters of B-doped solar cell were more durable against the UV light.

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