Electronic structures and stability of Ni/Bi2Te3 and Co/Bi2Te3 interfaces

KAUST Repository

Xiong, Ka

2010-03-04

We investigate the electronic structures and stability for Ni/Bi 2Te3, NiTe/Bi2Te3, Co/Bi 2Te3 and CoTe2/Bi2Te3 interfaces by first-principles calculations. It is found that the surface termination strongly affects the band alignment. Ni and Co are found to form Ohmic contacts to Bi2Te3. The interface formation energy for Co/Bi2Te3 interfaces is much lower than that of Ni/Bi2Te3 interfaces. Furthermore, we found that NiTe on Bi2Te3 is more stable than Ni, while the formation energies for Co and CoTe2 on Bi2Te3 are comparable. © 2010 IOP Publishing Ltd.

NiCo-lead zirconium titanate-NiCo trilayered magnetoelectric composites prepared by electroless deposition

Energy Technology Data Exchange (ETDEWEB)

Zhou, M. H.; Wang, Y. G.; Bi, K., E-mail: bike@bupt.edu.cn [State Key Laboratory of Information Photonics and Optical Communications and School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Fan, H. P. [School of Mechanical and Electrical Engineering, Qingdao Technological University Qindao College, Qingdao 266106 (China); Zhao, Z. S. [Shandong Engineering Consulting Institute, Jinan 250013 (China)

2015-04-15

The NiCo layers with various Ni/Co atomic ratio have been successfully electroless deposited on PZT layers by varying the bath composition. As the cobalt atomic ratio in the deposited layer increases from 17.2 to 54.8 wt%, the magnetostrictive coefficient decreases. The magnetoelectric effect depends strongly on the magnetostrictive properties of magnetostrictive phase. The magnetoelectric coefficient of NiCo/PZT/NiCo trilayers increases with Ni/Co atomic ratio of the deposited NiCo layers increasing from 45:55 to 83:17. A maximum ME voltage coefficient of α{sub E,31} = 2.8 V ⋅ cm{sup −1} ⋅ Oe{sup −1} is obtained at a frequency of about 88 kHz, which makes these trilayers suitable for applications in actuators, transducers and sensors.

Formation of fine aggregate structure by solid-state displacement reaction of Ti with CoO or NiO. CoO oyobi NiO to Ti kan no koso chikan hanno ni yoru bisai fukugo soshiki no seisei

Energy Technology Data Exchange (ETDEWEB)

Taimatsu, H; Kaneko, H [Akita Univ., Akita (Japan). Mining College; Wada, K [Akita Univ., Akita (Japan). Graduate School

1992-09-20

As a result of search for systems which have aggregate structures, the displacement reaction products of Ti with CoO or NiO are found to have aggregate structures in which the produced oxides and metals are entangled with each other. The displacement reaction of Ti with CoO or NiO is investigated at the temperature of 1273K. In the reaction of either couple, aggregate products are produced, and reacted layer is observed in the TiO2 matrix wherein Co or Ni phases are three dimensionally entangled in finely dispersed state of micron order. 2 layers of cavitated and dense TiO2 layers are found in the reacted layer. The thicknesses of the reacted layer are not constant according to locations, but thick portions are grown obeying the parabolic rate law. As a result of the study on the possibility of fabricating cermet by the reaction between powders, finely mixed characteristic structures are found to be easily obtained using systems which can produce aggregate structures. 24 refs., 9 figs.

NiCo2O4 particles with diamond-shaped hexahedron structure for high-performance supercapacitors

Science.gov (United States)

Li, Yanfang; Hou, Xiaojuan; Zhang, Zengxing; Hai, Zhenyin; Xu, Hongyan; Cui, Danfeng; Zhuiykov, Serge; Xue, Chenyang

2018-04-01

Nickel cobalt oxide (NiCo2O4) particles with a diamond-shaped hexahedral porous sheet structure are successfully synthesized by a facile hydrothermal method, followed by calcination in one step. NiCo2O4-I and NiCo2O4-II particles are prepared using the same method with different contents of urea (CO(NH2)2) and ammonium fluoride (NH4F). The different morphologies of the NiCo2O4-I and NiCo2O4-II particles illustrate that CO(NH2)2 and NH4F play an important role in crystal growth. To verify the influence of NH4F and CO(NH2)2 on the morphology of the NiCo2O4 particles, the theory of crystal growth morphology is analyzed. The electrochemical measurements show that NiCo2O4 particles exhibit a high specific capacitance. At a current density of 1.0 mA cm-2, the mass specific capacitances of the NiCo2O4-I and NiCo2O4-II electrodes are 690.75 and 1710.9 F g-1, respectively, in a 6 M KOH aqueous electrolyte. The specific capacitances of the NiCo2O4-I and NiCo2O4-II electrodes remain ∼95.95% and ∼70.58% of the initial capacitance values after 5000 cycles, respectively. According to the two-electrode test, the NiCo2O4-II//AC asymmetric electrodes exhibited an ultrahigh energy density of 64.67 Wh kg-1 at the power density of 12 kW kg-1, demonstrating its excellent application potential as an electrode material for supercapacitors.

CO{sub 2} capture in Mg oxides doped with Fe and Ni; Captura de CO{sub 2} en oxidos de Mg dopados con Fe y Ni

Energy Technology Data Exchange (ETDEWEB)

Sanchez S, I. F.

2016-07-01

In this work the CO{sub 2} capture-desorption characteristics in Mg oxides doped with Fe and Ni obtained by the direct oxidation of Mg-Ni and Mg-Fe mixtures are presented. Mixtures of Mg-Ni and Mg-Fe in a different composition were obtained by mechanical milling in a Spex-type mill in a controlled atmosphere of ultra high purity argon at a weight / weight ratio of 4:1 powder using methanol as a lubricating agent, for 20 h. The powders obtained by mechanical milling showed as main phase, the Mg with nanocrystalline structure. Subsequently, the mixtures of Mg-Ni and Mg-Fe were oxidized within a muffle for 10 min at 600 degrees Celsius. By means of X-ray diffraction analysis, the Mg O with nano metric grain size was identified as the main phase, which was determined by the Scherrer equation. In the Mg O doped with Ni, was identified that as the Ni amount 1 to 5% by weight dispersed in the Mg O matrix was increased, the main peak intensity of the Ni phase increased, whereas in the Mg O doped with Fe was observed by XRD, that the Fe{sub 2}O{sub 3} phase was present and by increasing the amount of Fe (1 to 5% by weight) dispersed in the crystalline phase of Mg O, the intensity of this impurity also increased. Sem-EDS analysis showed that the Ni and Fe particles are dispersed homogeneously in the Mg O matrix, and the particles are porous, forming agglomerates. Through energy dispersive spectroscopy analysis, the elemental chemical composition obtained is very close to the theoretical composition. The capture of CO{sub 2} in the Mg O-1% Ni was carried out in a Parr reactor at different conditions of pressure, temperature and reaction time. Was determined that under the pressure of 0.2 MPa at 26 degrees Celsius for 1 h of reaction, the highest CO{sub 2} capture of 7.04% by weight was obtained, while in Mg O-1% Fe the CO{sub 2} capture was 6.32% by weight. The other magnesium oxides doped in 2.5 and 5% by weight Ni and Fe showed lower CO{sub 2} capture. The different stages

Full synergistic effect of hydrothermal NiCo2O4 nanosheets/CuCo2O4 nanocones supported on Ni foam for high-performance asymmetric supercapacitors

Science.gov (United States)

Wen, Shiyang; Liu, Yu; Bai, Hongye; Shao, Rong; Xu, Wei; Shi, Weidong

2018-06-01

In this work, a series of NiCo2O4/CuCo2O4 composites were prepared by a two-step hydrothermal method. The optimized NiCo2O4/CuCo2O4 electrode shows more than 5 times area capacitance (4.97 F cm-2) than pure NiCo2O4 at the current density of 1 mA cm-2. The best performance of sample assembled an asymmetric supercapacitor could reach up to 42 F g-1 at the current density of 1 A g-1. In addition, the maximum energy density of 15 W h kg-1 was achieved with the power density of 814 W kg-1. The as-prepared active electrode material also reveals excellent cycling stability with 90.6% capacitance retention after 5000 cycles. These results indicate potential application in developing energy storage devices with high energy density power density.

The LiyNi0.2Mn0.2Co0.6O2 electrode materials: A structural and magnetic study

International Nuclear Information System (INIS)

Labrini, Mohamed; Saadoune, Ismael; Almaggoussi, Abdelmajid; Elhaskouri, Jamal; Amoros, Pedro

2012-01-01

Graphical abstract: EPR signal of the Li 0.6 Co 0.6 Ni 0.2 Mn 0.2 O 2 composition showing that Mn 4+ ions are the solely paramagnetic ions in the structure. Highlights: ► LiCo 0.6 Ni 0.2 Mn 0.2 O 2 was prepared by the combustion method with sucrose as a fuel. ► Chemical delithiaition was performed by using NO 2 BF 4 oxidizing agent. ► The rhombohedral symmetry was preserved upon lithium removal. ► Lithium extraction leads to Ni 2+ oxidation to Ni 4+ followed by Co 3+ oxidation. ► The EPR narrow signal of Li 0.6 Co 0.6 Ni 0.2 Mn 0.2 O 2 is due to the only active Mn 4+ ions. -- Abstract: Layered LiNi 0.2 Mn 0.2 Co 0.6 O 2 phase, belonging to a solid solution between LiNi 1/2 Mn 1/2 O 2 and LiCoO 2 most commercialized cathodes, was prepared via the combustion method at 900 °C for a short time (1 h). Structural and magnetic properties of this material during chemical extraction were investigated. The powders adopted the α-NaFeO 2 structure with almost none of the well-known Li/Ni cation disorder. The analysis of the magnetic properties in the paramagnetic domain agrees with the combination of Ni 2+ (S = 1), Co 3+ (S = 0) and Mn 4+ (S = 3/2) spin-only values. X-ray analysis of the chemically delithiated Li y Ni 0.2 Mn 0.2 Co 0.6 O 2 reveals no structural transition. The process of lithium extraction from and insertion into LiNi 0.2 Mn 0.2 Co 0.6 O 2 was discussed on the basis of ex situ EPR experiments and magnetic susceptibility. Oxidation of Ni 2+ (S = 1) to Ni 3+ (S = 1/2) and to Ni 4+ (S = 0) was observed upon lithium removal.

High-frequency permeability of electroplated CoNiFe and CoNiFe-C alloys

International Nuclear Information System (INIS)

Rhen, Fernando M.F.; McCloskey, Paul; O'Donnell, Terence; Roy, Saibal

2008-01-01

We have investigated CoNiFe and CoNiFe-C electrodeposited by pulse reverse plating (PRP) and direct current (DC) techniques. CoNiFe(PRP) films with composition Co 59.4 Fe 27.7 Ni 12.8 show coercivity of 95 A m -1 (1.2 Oe) and magnetization saturation flux (μ 0 M s ) of 1.8 T. Resistivity of CoNiFe (PRP) is about 24 μΩ cm and permeability remains almost constant μ r ' ∼475 up to 30 MHz with a quality factor (Q) larger than 10. Additionally, the permeability spectra analysis shows that CoNiFe exhibits a classical eddy current loss at zero bias field and ferromagnetic resonance (FMR) when biased with 0.05 T. Furthermore, a crossover between eddy current and FMR loss is observed for CoNiFe-PRP when baised with 0.05 T. DC and PRP plated CoNiFe-C, which have resistivity and permeability of 85, 38 μΩ cm, μ r '=165 and 35 with Q>10 up to 320 MHz, respectively, showed only ferromagnetic resonance losses. The ferromagnetic resonance peaks in CoNiFe and CoNiFe-C are broad and resembles a Gaussian distribution of FMR frequencies. The incorporation of C to CoNiFe reduces eddy current loss, but also reduces the FMR frequency

CO_2 capture in Mg oxides doped with Fe and Ni

International Nuclear Information System (INIS)

Sanchez S, I. F.

2016-01-01

In this work the CO_2 capture-desorption characteristics in Mg oxides doped with Fe and Ni obtained by the direct oxidation of Mg-Ni and Mg-Fe mixtures are presented. Mixtures of Mg-Ni and Mg-Fe in a different composition were obtained by mechanical milling in a Spex-type mill in a controlled atmosphere of ultra high purity argon at a weight / weight ratio of 4:1 powder using methanol as a lubricating agent, for 20 h. The powders obtained by mechanical milling showed as main phase, the Mg with nanocrystalline structure. Subsequently, the mixtures of Mg-Ni and Mg-Fe were oxidized within a muffle for 10 min at 600 degrees Celsius. By means of X-ray diffraction analysis, the Mg O with nano metric grain size was identified as the main phase, which was determined by the Scherrer equation. In the Mg O doped with Ni, was identified that as the Ni amount 1 to 5% by weight dispersed in the Mg O matrix was increased, the main peak intensity of the Ni phase increased, whereas in the Mg O doped with Fe was observed by XRD, that the Fe_2O_3 phase was present and by increasing the amount of Fe (1 to 5% by weight) dispersed in the crystalline phase of Mg O, the intensity of this impurity also increased. Sem-EDS analysis showed that the Ni and Fe particles are dispersed homogeneously in the Mg O matrix, and the particles are porous, forming agglomerates. Through energy dispersive spectroscopy analysis, the elemental chemical composition obtained is very close to the theoretical composition. The capture of CO_2 in the Mg O-1% Ni was carried out in a Parr reactor at different conditions of pressure, temperature and reaction time. Was determined that under the pressure of 0.2 MPa at 26 degrees Celsius for 1 h of reaction, the highest CO_2 capture of 7.04% by weight was obtained, while in Mg O-1% Fe the CO_2 capture was 6.32% by weight. The other magnesium oxides doped in 2.5 and 5% by weight Ni and Fe showed lower CO_2 capture. The different stages of mass loss and thermal

Coral reefs as fixers of CO2. Sangosho ni yoru nisanka tanso no kotei

Energy Technology Data Exchange (ETDEWEB)

Yamamuro, M [Geological Survey of Japan, Tsukuba (Japan)

1992-07-25

This paper explains CO2 fixing mechanisms in coral reefs and technologies to construct coral reef eco-factories. A coral reef fists CO2 through two routes of photosynthesis and calcification, with both processes proceeding conjugately. Calcification is driven by the photosynthesis that proceeds at a rate more than ten times faster than the calcification. The Geological Survey of Japan is working on elucidating CO2 fixing mechanisms in coral reefs and studying coral reef eco-factory structuring technologies to utilize the capability of the mechanisms at a possible maximum extent. This study is directed to optimizing site conditions for coral reefs, optimal arrangements and environmental conditions for clusters, and production process determining factors. The structuring technologies may include controlling water temperatures, water flows, nutritious salts, and suspended substances that match optimal CO2 fixing conditions in coral reefs; seeding technologies for coral reef organisms; aquaculture techniques utilizing fixed CO2; combination with cultivating techniques; and combination with new energy technologies including sea water temperature difference power generation to control water flows and maintain facilities. 4 refs., 5 figs.

Promotion Effect of CaO Modification on Mesoporous Al2O3-Supported Ni Catalysts for CO2 Methanation

Directory of Open Access Journals (Sweden)

Wen Yang

2016-01-01

Full Text Available The catalysts Ni/Al2O3 and CaO modified Ni/Al2O3 were prepared by impregnation method and applied for methanation of CO2. The catalysts were characterized by N2 adsorption/desorption, temperature-programmed reduction of H2 (H2-TPR, X-ray diffraction (XRD, and temperature-programmed desorption of CO2 and H2 (CO2-TPD and H2-TPD techniques, respectively. TPR and XRD results indicated that CaO can effectively restrain the growth of NiO nanoparticles, improve the dispersion of NiO, and weaken the interaction between NiO and Al2O3. CO2-TPD and H2-TPD results suggested that CaO can change the environment surrounding of CO2 and H2 adsorption and thus the reactants on the Ni atoms can be activated more easily. The modified Ni/Al2O3 showed better catalytic activity than pure Ni/Al2O3. Ni/CaO-Al2O3 showed high CO2 conversion especially at low temperatures compared to Ni/Al2O3, and the selectivity to CH4 was very close to 1. The high CO2 conversion over Ni/CaO-Al2O3 was mainly caused by the surface coverage by CO2-derived species on CaO-Al2O3 surface.

Ultrathin mesoporous NiCo{sub 2}O{sub 4} nanosheets supported on Ni foam as advanced electrodes for supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Yuan, Changzhou [Anhui Key Laboratory of Metal Materials and Processing, School of Materials Science and Engineering, Anhui University of Technology, Maanshan, 243002 (China); School of Chemical and Biomedical Engineering, Nanyang Technological University, 70 Nanyang Drive (Singapore); Li, Jiaoyang; Hou, Linrui [Anhui Key Laboratory of Metal Materials and Processing, School of Materials Science and Engineering, Anhui University of Technology, Maanshan, 243002 (China); Zhang, Xiaogang; Shen, Laifa [College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016 (China); Lou, Xiong Wen [School of Chemical and Biomedical Engineering, Nanyang Technological University, 70 Nanyang Drive (Singapore)

2012-11-07

A facile two-step method is developed for large-scale growth of ultrathin mesoporous nickel cobaltite (NiCo{sub 2}O{sub 4}) nanosheets on conductive nickel foam with robust adhesion as a high-performance electrode for electrochemical capacitors. The synthesis involves the co-electrodeposition of a bimetallic (Ni, Co) hydroxide precursor on a Ni foam support and subsequent thermal transformation to spinel mesoporous NiCo{sub 2}O{sub 4}. The as-prepared ultrathin NiCo{sub 2}O{sub 4} nanosheets with the thickness of a few nanometers possess many interparticle mesopores with a size range from 2 to 5 nm. The nickel foam supported ultrathin mesoporous NiCo{sub 2}O{sub 4} nanosheets promise fast electron and ion transport, large electroactive surface area, and excellent structural stability. As a result, superior pseudocapacitive performance is achieved with an ultrahigh specific capacitance of 1450 F g{sup -1}, even at a very high current density of 20 A g{sup -1}, and excellent cycling performance at high rates, suggesting its promising application as an efficient electrode for electrochemical capacitors. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

NiCo2O4-Based Supercapacitor Nanomaterials

Science.gov (United States)

Wang, Chenggang; Zhou, E; He, Weidong; Deng, Xiaolong; Huang, Jinzhao; Ding, Meng; Wei, Xianqi; Liu, Xiaojing; Xu, Xijin

2017-01-01

In recent years, the research on supercapacitors has ushered in an explosive growth, which mainly focuses on seeking nano-/micro-materials with high energy and power densities. Herein, this review will be arranged from three aspects. We will summarize the controllable architectures of spinel NiCo2O4 fabricated by various approaches. Then, we introduce their performances as supercapacitors due to their excellent electrochemical performance, including superior electronic conductivity and electrochemical activity, together with the low cost and environmental friendliness. Finally, the review will be concluded with the perspectives on the future development of spinel NiCo2O4 utilized as the supercapacitor electrodes. PMID:28336875

NiCo2O4-Based Supercapacitor Nanomaterials

Directory of Open Access Journals (Sweden)

Chenggang Wang

2017-02-01

Full Text Available In recent years, the research on supercapacitors has ushered in an explosive growth, which mainly focuses on seeking nano-/micro-materials with high energy and power densities. Herein, this review will be arranged from three aspects. We will summarize the controllable architectures of spinel NiCo2O4 fabricated by various approaches. Then, we introduce their performances as supercapacitors due to their excellent electrochemical performance, including superior electronic conductivity and electrochemical activity, together with the low cost and environmental friendliness. Finally, the review will be concluded with the perspectives on the future development of spinel NiCo2O4 utilized as the supercapacitor electrodes.

Lanthanum and cerium co-modified Ni/SiO2 catalyst for CO methanation from syngas

Science.gov (United States)

Gong, Dandan; Li, Shuangshuang; Guo, Shaoxia; Tang, Honggui; Wang, Hong; Liu, Yuan

2018-03-01

Sintering of active metal nanoparticles (NPs) and carbon deposition is critical problems for many metal catalysts, such as nickel based catalysts for generating methane from syngas. To improve the resistance to the sintering and carbon deposition, a new scheme was proposed in this work. Lanthanum and cerium co-modified Ni/SiO2 catalysts were synthesized by using perovskite type oxide of La1-xCexNiO3 loaded on SiO2 as the precursor. In a nanocrystallite of La1-xCexNiO3, ions of nickel, lanthanum and cerium are evenly mixed at atomic level and confined in the nanocrystallite, therefore, Ni NPs and the two promoters of La2O3 and CeO2 should be in close contact and highly dispersed on SiO2 after reduction. The catalysts were characterized by using XRD, TEM, BET, H2-TPD, XPS, TG and Raman techniques. Compared with the mono-promoted catalysts, the bi-promoted La0.75Ce0.25NiO3/SiO2 showed much better resistance to carbon deposition, higher resistance to sintering and higher activity for CO methanation, which are attributed to co-eliminating effect of the two promoters for the deposited carbon, confinement of the interacted two promoters for Ni NPs and the higher dispersion of Ni NPs derived from the smaller size of La0.75Ce0.25NiO3.

Heterogeneous NiCo2O4@polypyrrole core/sheath nanowire arrays on Ni foam for high performance supercapacitors

Science.gov (United States)

Hu, Jing; Li, Minchan; Lv, Fucong; Yang, Mingyang; Tao, Pengpeng; Tang, Yougen; Liu, Hongtao; Lu, Zhouguang

2015-10-01

A novel heterogeneous NiCo2O4@PPy core/sheath nanowire arrays are directly grown on Ni foam involving three facile steps, hydrothermal synthesis and calcination of NiCo2O4 nanowire arrays and subsequent in-situ oxidative polymerization of polypyrrole (PPy). When investigated as binder- and conductive additive-free electrodes for supercapacitors (SCs) in 6 M KOH, the NiCo2O4@PPy core/sheath nanowire arrays exhibit high areal capacitance of 3.49 F cm-2 at a discharge current density of 5 mA cm-2, which is almost 1.5 times as much as the pristine NiCo2O4 (2.30 F cm-2). More importantly, it can remain 3.31 F cm-2 (94.8% retention) after 5000 cycles. The as-obtained electrode also displays excellent rate capability, whose areal capacitance can still remain 2.79 F cm-2 while the discharge current density is increased to 50 mA cm-2. The remarkable electrochemical performance is mainly attributed to the unique heterogeneous core/sheath nanowire-array architectures.

Poly(o-phenylenediamine)/NiCoFe2O4 nanocomposites: Synthesis, characterization, magnetic and dielectric properties

Science.gov (United States)

Kannapiran, Nagarajan; Muthusamy, Athianna; Chitra, Palanisamy; Anand, Siddeswaran; Jayaprakash, Rajan

2017-02-01

In this study, poly(o-phenylenediamine) (PoPD)/NiCoFe2O4 nanocomposites were synthesized by in-situ oxidative chemical polymerization method with different amount of NiCoFe2O4 nanoparticles. The NiCoFe2O4 nanoparticles were prepared by auto-combustion method. The structural, morphological, thermal properties of the synthesized PoPD/NiCoFe2O4 nanocomposites were characterized by fourier transform infrared spectrum (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Magnetic properties of NiCoFe2O4 nanoparticles and PoPD/NiCoFe2O4 nanocomposites were studied by vibrating sample magnetometer (VSM). The FTIR and XRD techniques were used to confirm the formation of PoPD/NiCoFe2O4 nanocomposites. The average crystalline size of NiCoFe2O4 nanoparticles and PoPD/NiCoFe2O4 nanocomposites were calculated from XRD. From the SEM analysis, spherical morphology of the PoPD was confirmed. The TGA results showed that the NiCoFe2O4 nanoparticles have improved the thermal stability of PoPD. Dielectric properties of PoPD/NiCoFe2O4 nanocomposites at different temperatures have been carried in the frequency range 50 Hz to 5 MHz.

Flexible Asymmetric Threadlike Supercapacitors Based on NiCo2 Se4 Nanosheet and NiCo2 O4 /Polypyrrole Electrodes.

Science.gov (United States)

Wang, Qiufan; Ma, Yun; Wu, Yunlong; Zhang, Daohong; Miao, Menghe

2017-04-10

Flexible threadlike supercapacitors with improved performance are needed for many wearable electronics applications. Here, we report a high performance flexible asymmetric all-solid-state threadlike supercapacitor with a NiCo 2 Se 4 positive electrode and a NiCo 2 O 4 @PPy (PPy: polypyrrole) negative electrode. The as-prepared electrodes display outstanding volume specific capacitance (14.2 F cm -3 ) and excellent cycling performance (94 % retention after 5000 cycles at 0.6 mA) owing to their nanosheet and nanosphere structures. The asymmetric all-solid-state threadlike supercapacitor expanded the stability voltage window from 0-1.0 V to 0-1.7 V and exhibits high volume energy density (5.18 mWh cm -3 ) and superior flexibility under different bending conditions. This study provides a scalable method for fabricating high performance flexible supercapacitors from easily available materials for use in wearable and portable electronics. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

NiCo2S4 nanosheet-decorated 3D, porous Ni film@Ni wire electrode materials for all solid-state asymmetric supercapacitor applications.

Science.gov (United States)

Saravanakumar, Balasubramaniam; Jayaseelan, Santhana Sivabalan; Seo, Min-Kang; Kim, Hak-Yong; Kim, Byoung-Suhk

2017-12-07

Wire type supercapacitors with high energy and power densities have generated considerable interest in wearable applications. Herein, we report a novel NiCo 2 S 4 -decorated 3D, porous Ni film@Ni wire electrode for high performance supercapacitor application. In this work, a facile method is introduced to fabricate a 3D, porous Ni film deposited on a Ni wire as a flexible electrode, followed by decoration with NiCo 2 S 4 as an electroactive material. The fabricated NiCo 2 S 4 -decorated 3D, porous Ni film@Ni wire electrode displays a superior performance with an areal and volumetric capacitance of 1.228 F cm -2 and 199.74 F cm -3 , respectively, at a current density of 0.2 mA cm -1 with a maximum volumetric energy and power density (E V : 6.935 mW h cm -3 ; P V : 1.019 W cm -3 ). Finally, the solid state asymmetric wire type supercapacitor is fabricated using the fabricated NiCo 2 S 4 -decorated 3D, porous Ni film@Ni wire as a positive electrode and N-doped reduced graphene oxide (N-rGO) as a negative electrode and this exhibits good areal and volumetric capacitances of C A : 0.12 F cm -2 and C V : 19.57 F cm -2 with a higher rate capability (92%). This asymmetric wire type supercapacitor demonstrates a low leakage current and self-discharge with a maximum volumetric energy (E V : 5.33 mW h cm -3 ) and power (P V : 855.69 mW cm -3 ) density.

Hierarchically porous Ni monolith@branch-structured NiCo2O4 for high energy density supercapacitors

Directory of Open Access Journals (Sweden)

Mengjie Xu

2016-06-01

Full Text Available A variety of NiCo2O4 nanostrucutures ranging from nanowire to nanoplate and branched structures were successfully prepared via a simple hydrothermal process. The experimental results show that NiCo2O4 with branched structures possesses the best overall electrochemical performance. The improvement of energy density was explored in terms of hierarchically three-dimensional (3D metal substrates and a high specific area capacitance, and area energy density is obtained with hierarchically porous Ni monolith synthesized through a controlled combustion procedure.

Electronic structure of Co(III) doped bromo-bridged Ni complexes, [Ni1-xCox(chxn)2Br]Br2.

Science.gov (United States)

Xie, Jimin; Wu, Hashen; Kawakami, Daisuke; Iguchi, Hiroaki; Takaishi, Shinya; Yamashita, Masahiro; Matsuzaki, Hiroyuki; Okamoto, Hiroshi; Tanaka, Hisaaki; Kuroda, Shin-ichi

2008-03-17

This article describes the electronic structure of the Co(III) doped Br bridged Ni(III) complexes, [Ni(1-x)Cox(chxn)2Br]Br2 (x = 0.01, 0.02, 0.05, and 0.11) by using a optical spectroscopy, scanning tunneling microscopy (STM), and electron spin resonance spectroscopy. In the optical reflectivity spectrum, the new band was formed at about 0.5 eV, which is reasonably recognized as the d(z2) band of doped Co(III) ions. In the STM images of [Ni(1-x)Cox(chxn)2Br]Br2, the bright spots attributable to the tunnel current from the Fermi level of the STM tip to the conduction band of the sample were observed. In addition, some brighter spots were also observed. Because the number of the brighter spots is in good agreement with that of doped Co species, the brighter spots can be assigned to doped Co(III) sites. These are reasonably explained by the tunnel current from the Fermi level of the tip to the d(z2) band of Co(III). The Curie spin concentration was gradually increased with increasing Co(III) ions, which is explained by the scissions of the S = 1/2 1D antiferromagnetic chains.

Core/shell structure NiCo2O4@MnCo2O4 nanofibers fabricated by different temperatures for high-performance supercapacitors

Science.gov (United States)

Wang, Qing; Qin, Xuefeng; Jiang, Pengcheng; Dai, Jianfeng; Li, Weixue; Gao, Haoran

2018-03-01

Core/shell structure NiCo2O4@MnCo2O4 nanofibers (NiCo2O4@MnCo2O4 NFs) were prepared by a facile co-electrospinning method and heat treatment. The composites annealed at 500 °C have a complete, continuously obvious core/shell structure, and clear interface of composites with good morphology, while annealed at 600 °C were stacked on each other and were unable to sustain three-dimensional network structures and 700 °C calcination have completely lost one-dimensional structure. The core NiCo2O4 is about 70 nm in diameter and the MnCo2O4 shell behaves a thickness about 60 nm. When investigated as an electrode material for supercapacitors, the NiCo2O4@MnCo2O4 NFs annealed at 500 °C exihibited the specific capacitance of 463 F g-1 (0.926 F cm-2) at 1 A g-1, higher than that annealed at 600 °C 362 F g-1, 1 A g-1 (0.724 F cm-2, 1 A g-1) and 700 °C 283 F g-1, 1 A g-1 (0.566 F cm-2, 1 A g-1). These results suggest that core/shell NiCo2O4@MnCo2O4 NFs annealed at 500 °C have formed a good morphology with continuously complete core/shell structure which lead to good properties would be potential electrodes for supercapacitors.

NiCo2O4 nanosheets in-situ grown on three dimensional porous Ni film current collectors as integrated electrodes for high-performance supercapacitors

Science.gov (United States)

Wang, Tao; Guo, Ying; Zhao, Bo; Yu, Shuhui; Yang, Hai-Peng; Lu, Daniel; Fu, Xian-Zhu; Sun, Rong; Wong, Ching-Ping

2015-07-01

Three dimensional interconnected hierarchical porous Ni films are easily fabricated as effective current collectors through hydrogen bubble template electrochemical deposition. The binder-free integrated electrodes of spinel NiCo2O4 nanosheets directly coated the three dimensional porous Ni films are facilely obtained through successively electrochemical co-deposition of Ni/Co alloy layer then followed by subsequent annealing at 350 °C in air. Compared with NiCo2O4 nanosheets on smooth Ni foil or porous NiO/Ni film electrodes, the porous NiCo2O4/Ni integrated film electrodes for supercapacitors demonstrate remarkably higher area specific capacitance. The porous NiCo2O4/Ni film electrodes also exhibit excellent rate capability and cycling stability. The super electrochemical capacitive performances are attributed to the unique integrated architecture of NiCo2O4 nanosheets in-situ grown on three dimensional continuous hierarchical porous Ni collector collectors, which could provide large electrode-electrolyte interface area, high active sites, low contact resistance between current collector and active materials, fast electron conduction and ion/electrolyte diffusion.

Layered Ni(OH)2-Co(OH)2 films prepared by electrodeposition as charge storage electrodes for hybrid supercapacitors.

Science.gov (United States)

Nguyen, Tuyen; Boudard, Michel; Carmezim, M João; Montemor, M Fátima

2017-01-04

Consecutive layers of Ni(OH) 2 and Co(OH) 2 were electrodeposited on stainless steel current collectors for preparing charge storage electrodes of high specific capacity with potential application in hybrid supercapacitors. Different electrodes were prepared consisting on films of Ni(OH) 2 , Co(OH) 2 , Ni 1/2 Co 1/2 (OH) 2 and layered films of Ni(OH) 2 on Co(OH) 2 and Co(OH) 2 on Ni(OH) 2 to highlight the advantages of the new architecture. The microscopy studies revealed the formation of nanosheets in the Co(OH) 2 films and of particles agglomerates in the Ni(OH) 2 films. Important morphological changes were observed in the double hydroxides films and layered films. Film growth by electrodeposition was governed by instantaneous nucleation mechanism. The new architecture composed of Ni(OH) 2 on Co(OH) 2 displayed a redox response characterized by the presence of two peaks in the cyclic voltammograms, arising from redox reactions of the metallic species present in the layered film. These electrodes revealed a specific capacity of 762 C g -1 at the specific current of 1 A g -1 . The hybrid cell using Ni(OH) 2 on Co(OH) 2 as positive electrode and carbon nanofoam paper as negative electrode display specific energies of 101.3 W h g -1 and 37.8 W h g -1 at specific powers of 0.2 W g -1 and 2.45 W g -1 , respectively.

Water-Gas Shift and CO Methanation Reactions over Ni-CeO2(111) Catalysts

Energy Technology Data Exchange (ETDEWEB)

S Senanayake; J Evans; S Agnoli; L Barrio; T Chen; J Hrbek; J Rodriguez

2011-12-31

X-ray and ultraviolet photoelectron spectroscopies were used to study the interaction of Ni atoms with CeO{sub 2}(111) surfaces. Upon adsorption on CeO{sub 2}(111) at 300 K, nickel remains in a metallic state. Heating to elevated temperatures (500-800 K) leads to partial reduction of the ceria substrate with the formation of Ni{sup 2+} species that exists as NiO and/or Ce{sub 1-x}Ni{sub x}O{sub 2-y}. Interactions of nickel with the oxide substrate significantly reduce the density of occupied Ni 3d states near the Fermi level. The results of core-level photoemission and near-edge X-ray absorption fine structure point to weakly bound CO species on CeO{sub 2}(111) which are clearly distinguishable from the formation of chemisorbed carbonates. In the presence of Ni, a stronger interaction is observed with chemisorption of CO on the admetal. When the Ni is in contact with Ce{sup +3} cations, CO dissociates on the surface at 300 K forming NiC{sub x} compounds that may be involved in the formation of CH{sub 4} at higher temperatures. At medium and large Ni coverages (>0.3 ML), the Ni/CeO{sub 2}(111) surfaces are able to catalyze the production of methane from CO and H{sub 2}, with an activity slightly higher than that of Ni(100) or Ni(111). On the other hand, at small coverages of Ni (<0.3 ML), the Ni/CeO{sub 2}(111) surfaces exhibit a very low activity for CO methanation but are very good catalysts for the water-gas shift reaction.

Properties of LiCoO{sub 2}-coated NiO MCFC cathode

Energy Technology Data Exchange (ETDEWEB)

Kuk, S.T.; Kim, C.K.; Chun, H.S. [Korea Univ., Seoul (Korea, Republic of); Kwon, H.J. [Samsung Electronics Co. Ltd., Suwon (Korea, Republic of)

1996-12-31

PVA-assisted sol-gel method is useful in producing metal oxides with large surface area at low temperature. We fabricated LiCoO{sub 2}-coated NiO(LC-NiO) cathode by PVA-assisted sol-gel method and measured its properties, The electrical conductivity of LC-NiO cathode was measured to be more than 5 times as high as that of NiO and unit cell test showed improved performance. From the SEM images and Raman spectra. we confirmed that the structure of LC-NiO was different from that of NiO. For 250 hours of steady operation of unit cells. the mean voltage of the cells were 0.78V for NiO and 0.85V for LiCoO{sub 2}-Coated NiO at a current density of l50mA/cm{sup 2}.

Hierarchical Core/Shell NiCo2O4@NiCo2O4 Nanocactus Arrays with Dual-functionalities for High Performance Supercapacitors and Li-ion Batteries

Science.gov (United States)

Cheng, Jinbing; Lu, Yang; Qiu, Kangwen; Yan, Hailong; Xu, Jinyou; Han, Lei; Liu, Xianming; Luo, Jingshan; Kim, Jang-Kyo; Luo, Yongsong

2015-07-01

We report the synthesis of three dimensional (3D) NiCo2O4@NiCo2O4 nanocactus arrays grown directly on a Ni current collector using a facile solution method followed by electrodeposition. They possess a unique 3D hierarchical core-shell structure with large surface area and dual-functionalities that can serve as electrodes for both supercapacitors (SCs) and lithium-ion batteries (LIBs). As the SC electrode, they deliver a remarkable specific capacitance of 1264 F g-1 at a current density of 2 A g-1 and ~93.4% of capacitance retention after 5000 cycles at 2 A g-1. When used as the anode for LIBs, a high reversible capacity of 925 mA h g-1 is achieved at a rate of 120 mA g-1 with excellent cyclic stability and rate capability. The ameliorating features of the NiCo2O4 core/shell structure grown directly on highly conductive Ni foam, such as hierarchical mesopores, numerous hairy needles and a large surface area, are responsible for the fast electron/ion transfer and large active sites which commonly contribute to the excellent electrochemical performance of both the SC and LIB electrodes.

Structural and magnetic properties of Ni-Zn and Ni-Zn-Co ferrites

Energy Technology Data Exchange (ETDEWEB)

Knyazev, A.V., E-mail: knyazevav@gmail.com [N.I. Lobachevsky State University of Nizhni Novgorod, Gagarin Prospekt 23/2, 603950 Nizhni Novgorod (Russian Federation); Zakharchuk, I.; Lähderanta, E. [Lappeenranta University of Technology, P.O. Box 20, FI-53851 Lappeenranta (Finland); Baidakov, K.V.; Knyazeva, S.S. [N.I. Lobachevsky State University of Nizhni Novgorod, Gagarin Prospekt 23/2, 603950 Nizhni Novgorod (Russian Federation); Ladenkov, I.V. [Joint-stock Company “Research and Production Company “Salut”, Nizhni Novgorod (Russian Federation)

2017-08-01

Highlights: • Ni-Zn and Ni-Zn-Co ferrite powders were prepared by the solid-state reaction at 1073 K. • The room temperature saturation magnetizations are 59.7 emu/g for Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and 57.1 emu/g for Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4}. • The coercivity of the samples is found to be much larger than that of bulk ferrites and increases with Co introduction. • The temperature dependences of magnetization exhibit large spin frustration and spin-glass-like behavior. - Abstract: Ni-Zn and Ni-Zn-Co ferrite powders with nominal compositions Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4} were prepared by the solid-state reaction synthesis with periodic regrinding during the calcination at 1073 K. The structure of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4} was refined assuming space group F d-3m. Scanning electron microscopy revealed the average sizes of the crystalline ferrite particles are 130–630 nm for Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and 140–350 nm for Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4}. The room temperature saturation magnetizations are 59.7 emu/g for Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and 57.1 emu/g for Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4}. The coercivity of the samples is found to be much larger than that of bulk ferrites and increases with Co introduction. The Curie temperature tends to increase upon Zn substitution by Co, as well. The temperature dependences of magnetization measured using zero-field cooled and field cooled protocols exhibit large spin frustration and spin-glass-like behavior.

CO2 fixation by coral reefs. Sangosho ni yoru nisanka tanso no kotei

Energy Technology Data Exchange (ETDEWEB)

Kayane, H [Geological Survey of Japan, Tsukuba (Japan)

1993-05-01

In order for a coral reef to be a CO2 absorbing source, a condition would have to be satisfied that, with respect to production of organic carbon through photosynthesis, a total production by coral reef organism association is large, and the ratio of the total production to a total consumption is more than one. A requirement that the ratio of inorganic carbon production through calcification be 1.5 or more must also be met. Measurements have been carried out at coral fields off the Ishigaki Island by the Geological Research Center. The measurement results revealed that production is high for both of organic carbon and inorganic carbon, surplus organic carbon is produced, and CO2 is absorbed into the coral reefs. It was also found by measuring the stable isotope ratio of nitrogen in coral reef organisms that nitrogen required for the production in the coral reefs is supplied from the atmosphere through nitrogen fixation. The paper adds a description that CaCO3 deposition in the coral reefs has peaked in 5000 years to 6000 years ago, and it is in a ceiling-hit condition now. 25 refs., 3 figs.

Porous Hollow Superlattice NiMn2O4/NiCo2O4 Mesocrystals as a Highly Reversible Anode Material for Lithium-Ion Batteries

Directory of Open Access Journals (Sweden)

Lingjun Li

2018-05-01

Full Text Available As a promising high-capacity anode material for Li-ion batteries, NiMn2O4 always suffers from the poor intrinsic conductivity and the architectural collapse originating from the volume expansion during cycle. Herein, a combined structure and architecture modulation is proposed to tackle concurrently the two handicaps, via a facile and well-controlled solvothermal approach to synthesize NiMn2O4/NiCo2O4 mesocrystals with superlattice structure and hollow multi-porous architecture. It is demonstrated that the obtained NiCo1.5Mn0.5O4 sample is made up of a new mixed-phase NiMn2O4/NiCo2O4 compound system, with a high charge capacity of 532.2 mAh g−1 with 90.4% capacity retention after 100 cycles at a current density of 1 A g−1. The enhanced electrochemical performance can be attributed to the synergistic effects of the superlattice structure and the hollow multi-porous architecture of the NiMn2O4/NiCo2O4 compound. The superlattice structure can improve ionic conductivity to enhance charge transport kinetics of the bulk material, while the hollow multi-porous architecture can provide enough void spaces to alleviate the architectural change during cycling, and shorten the lithium ions diffusion and electron-transportation distances.

Magnetic order in Pu2M3Si5 (M = Co, Ni)

International Nuclear Information System (INIS)

Bauer, E D; Tobash, P H; Mitchell, J N; Kennison, J A; Ronning, F; Scott, B L; Thompson, J D

2011-01-01

The physical properties including magnetic susceptibility, specific heat, and electrical resistivity of two new plutonium compounds Pu 2 M 3 Si 5 (M = Co, Ni) are reported. Pu 2 Ni 3 Si 5 crystallizes in the orthorhombic U 2 Co 3 Si 5 structure type, which can be considered a variant of the BaAl 4 tetragonal structure, while Pu 2 Co 3 Si 5 adopts the closely related monoclinic Lu 2 Co 3 Si 5 type. Magnetic order is observed in both compounds, with Pu 2 Ni 3 Si 5 ordering ferromagnetically at T C = 65 K then undergoing a transition into an antiferromagnetic state below T N = 35 K. Two successive magnetic transitions are also observed at T mag1 = 38 K and T mag2 = 5 K in Pu 2 Co 3 Si 5 . Specific heat measurements reveal that these two materials have a moderately enhanced Sommerfeld coefficient γ ∼ 100 mJ/mol Pu K 2 in the magnetic state with comparable RKKY and Kondo energy scales.

Graphene wrapped porous Co_3O_4/NiCo_2O_4 double-shelled nanocages with enhanced electrocatalytic performance for glucose sensor

International Nuclear Information System (INIS)

Xue, Bei; Li, Kezhi; Feng, Lei; Lu, Jinhua; Zhang, Leilei

2017-01-01

Highlights: • Graphene wrapped Co_3O_4/NiCo_2O_4 DSNCs has been prepared for detection of glucose. • Sensing performance was improved by synergy between electrocatalytic activity and efficient electron transport. • The sensor has excellent sensing performance with high sensitivity and low detection limit. • The developed method was successfully applied to detect glucose in human serum. - Abstract: Graphene (G) wrapped porous Co_3O_4/NiCo_2O_4 double-shelled nanocages (Co_3O_4/NiCo_2O_4 DSNCs@G) were prepared by the formation of Co_3O_4/NiCo_2O_4 DSNCs using zeolite imidazole frameworks-67 as template with the subsequent calcination and package of G by hydrothermal method. The abundant accessible active sites provided by the porous structure of Co_3O_4/NiCo_2O_4 DSNCs and efficient electron transport pathways for electrocatalytic reaction offered by the high conductive G worked very well together in a ferocious synergy, which endowed Co_3O_4/NiCo_2O_4 DSNCs@G with excellent electrocatalytic behaviors for determining glucose. A comparison between Co_3O_4/NiCo_2O_4 DSNCs without G packing and Co_3O_4/NiCo_2O_4 DSNCs@G showed that former had linear response window concentrations of 0.01-3.52 mM (correlation coefficient = 0.999), detection limit of 0.744 μM (S/N = 3) and sensitivity of 0.196 mA mM"−"1 cm"−"2, whereas the latter exhibited linear response window concentrations of 0.01-3.52 mM (correlation coefficient = 0.999), detection limit of 0.384 μM (S/N = 3) and sensitivity of 0.304 mA mM"−"1 cm"−"2. The combination of Co_3O_4/NiCo_2O_4 DSNCs and G was a meaningful strategy to fabricate high-performance non-enzyme glucose sensors with low detection limit, good selectivity and high sensitivity.

CO2 methanation on the catalyst of Ni/MCM-41 promoted with CeO2.

Science.gov (United States)

Wang, Xiaoliu; Zhu, Lingjun; Liu, Yincong; Wang, Shurong

2018-06-01

CO 2 as a raw feed combined with renewable hydrogen for the production of useful chemicals and alternative energy products is one of the solutions to environmental and energy problems. In this study, a series of Ni-xCeO 2 /MCM-41 catalysts with a nickel content of 20wt% were prepared through deposition precipitation method for CO 2 methanation. Different characterization methods, including BET, XRD, TEM, SEM, H 2 -TPR and H 2 -TPD were applied to help explore the influence mechanism of CeO 2 on Ni/MCM-41 in CO 2 methanation. It was found that all CeO 2 -promoted catalysts exhibited enhanced catalytic activity when compared to Ni/MCM-41. The catalyst modified with 20wt% CeO 2 showed the best catalytic performance, with CO 2 conversion and CH 4 selectivity of 85.6% and 99.8%, respectively, at the temperature of 380°C under atmospheric pressure. The synergetic effects among Ni 0 active sites, the promoter and the support, including nickel dispersion improvement and increased CO 2 adsorption sites due to the addition of CeO 2 , were considered as important factors for high reactivity of the promoted catalysts. The stability test showed that the promoted catalyst maintained its high reactivity after 30h. Copyright © 2017 Elsevier B.V. All rights reserved.

One-dimensional Co(II)/Ni(II) complexes of 2-hydroxyisophthalate: Structures and magnetic properties

International Nuclear Information System (INIS)

Wang, Kai; Zou, Hua-Hong; Chen, Zi-Lu; Zhang, Zhong; Sun, Wei-Yin; Liang, Fu-Pei

2015-01-01

The solvothermal reactions of 2-hydroxyisophthalic acid (H 3 ipO) with M(NO 3 ) 2 ∙6H 2 O (M=Co, Ni) afforded two complexes [Co 2 (HipO) 2 (Py) 2 (H 2 O) 2 ] (1) and [Ni(HipO)(Py)H 2 O] (2) (Py=pyridine). They exhibit similar zig-zag chain structures with the adjacent two metal centers connected by a anti-syn bridging carboxylate group from the HipO 2− ligand. The magnetic measurements reveal the dominant antiferromagnetic interactions and spin-canting in 1 while ferromagnetic interactions in 2. Both of them exhibit magnetocaloric effect (MCE) with the resulting entropy changes (−ΔS m ) of 12.51 J kg −1 K −1 when ΔH=50 kOe at 3 K for 1 and 11.01 J kg −1 K −1 when ΔH=50 kOe at 3 K for 2, representing the rare examples of one-dimensional complexes with MCE. - Graphical abstract: Synopsis: Two Co(II)/Ni(II) complexes with zig-zag chain structures have been reported. 1-Co shows cant-antiferromagnetism while 2-Ni shows ferromagnetism. Magnetocaloric effect is also found in both of them. - Highlights: • Two one-dimensional Co(II)/Ni(II) complexes were solvothermally synthesized. • The Co-complex exhibits canted antiferromagnetism. • The Ni-complex exhibits ferromagnetism. • Both of the complexes display magnetocaloric effect

Seaurchin-like hierarchical NiCo2O4@NiMoO4 core-shell nanomaterials for high performance supercapacitors.

Science.gov (United States)

Zhang, Qiang; Deng, Yanghua; Hu, Zhonghua; Liu, Yafei; Yao, Mingming; Liu, Peipei

2014-11-14

A novel electrode material of the three-dimensional (3D) multicomponent oxide NiCo2O4@NiMoO4 core-shell was synthesized via a facile two-step hydrothermal method using a post-annealing procedure. The uniform NiMoO4 nanosheets were grown on the seaurchin-like NiCo2O4 backbone to form a NiCo2O4@NiMoO4 core-shell material constructed by interconnected ultrathin nanosheets, so as to produce hierarchical mesopores with a large specific surface area of 100.3 m(2) g(-1). The porous feature and core-shell structure can facilitate the penetration of electrolytic ions and increases the number of electroactive sites. Hence, the NiCo2O4@NiMoO4 material exhibited a high specific capacitance of 2474 F g(-1) and 2080 F g(-1) at current densities of 1 A g(-1) and 20 A g(-1) respectively, suggesting that it has not only a very large specific capacitance, but also a good rate performance. In addition, the capacitance loss was only 5.0% after 1000 cycles of charge and discharge tests at the current density of 10 A g(-1), indicating high stability. The excellent electrochemical performance is mainly attributed to its 3D core-shell and hierarchical mesoporous structures which can provide unobstructed pathways for the fast diffusion and transportation of ions and electrons, a large number of active sites and good strain accommodation.

Ultrathin porous NiCo2O4 nanosheet arrays on flexible carbon fabric for high-performance supercapacitors.

Science.gov (United States)

Du, Jun; Zhou, Gang; Zhang, Haiming; Cheng, Chao; Ma, Jianmin; Wei, Weifeng; Chen, Libao; Wang, Taihong

2013-08-14

NiCo2O4 with higher specific capacitance is an excellent pseudocapacitive material. However, the bulk NiCo2O4 material prevents the achievement of high energy desity and great rate performance due to the limited electroactive surface area. In this work, NiCo2O4 nanosheet arrays were deposited on flexible carbon fabric (CF) as a high-performance electrode for supercapacitors. The NiCo2O4 arrays were constructed by interconnected ultrathin nanosheets (10 nm) with many interparticle pores. The porous feature of NiCo2O4 nanosheets increases the amount of electroactive sites and facilitates the electrolyte penetration. Hence, the NiCo2O4/CF composites exhibited a high specific capacitance of 2658 F g(-1) (2 A g(-1)), good rate performance, and superior cycling life, suggesting the NiCo2O4/CF is a promising electrode material for flexible electrochemical capacitors.

Photochemical deposition of NiCoO x thin films from Ni/Co heteronuclear triketonate complexes

International Nuclear Information System (INIS)

Buono-Core, G.E.; Tejos, M.; Cabello, G.; Guzman, N.; Hill, R.H.

2006-01-01

UV light irradiation of thin films of a polyketonate Ni/Co heteronuclear complex, NiCo(DBA) 2 [DBA, dibenzoylacetone)], spin coated on Si(1 0 0) substrates produced NiCoO x mixed oxides as amorphous films. On annealing at 600 deg. C under air, the mixed oxide film decomposed to NiO and CoO as indicated by XRD measurements. The morphology of the as-deposited films was examined by AFM analysis showing a smooth surface with low rms roughness values. The ratio of Ni/Co (1.08) present in the film reflects the stoichiometry in the starting compound within the experimental error, as shown by XPS analysis. The large amount of carbon (20.8%) detected on the surface of the film may be due to the presence of phenyl rings in the precursor complex

Shape-Controlled Synthesis of NiCo2 O4 Microstructures and Their Application in Supercapacitors.

Science.gov (United States)

Xiang, Nannan; Ni, Yonghong; Ma, Xiang

2015-09-01

The shape-controlled synthesis of NiCo2 O4 microstructures through a facile hydrothermal method and subsequent calcinations was explored. By employing CoSO4 , NiSO4 , and urea as the starting reactants, flower-like NiCo2 O4 microstructures were obtained at 100 °C after 5 h without the assistance of any additive and subsequent calcination at 300 °C for 2 h; dumbbell-like NiCo2 O4 microstructures were prepared at 150 °C after 5 h in the presence of trisodium citrate and subsequent calcination at 300 °C for 2 h. The as-prepared NiCo2 O4 microstructures were characterized by X-ray powder diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and (high-resolution) transmission electron microscopy. Both the flower-like and dumbbell-like NiCo2 O4 microstructures could be used as electrode materials for supercapacitors, and they exhibited excellent electrochemical performance, including high specific capacitance, good rate capability, and excellent long-term cycle stability. Simultaneously, the shape-dependent electrochemical properties of the product were investigated. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Facile synthesis of hybrid CNTs/NiCo2S4 composite for high performance supercapacitors

Science.gov (United States)

Li, Delong; Gong, Youning; Pan, Chunxu

2016-07-01

In this work, a novel carbon nanotubes (CNTs)/NiCo2S4 composite for high performance supercapacitors was prepared via a simple chemical bath deposition combined with a post-anion exchange reaction. The morphologies and phase structures of the composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS) and low-temperature sorption of nitrogen (BET). The electro-chemical tests revealed that the CNT/NiCo2S4 composite exhibited high electrochemical performance, because the CNTs were used as a conductive network for the NiCo2S4 hexagonal nanoplates. Compared with pure NiCo2S4 and the mechanically mixed CNTs/NiCo2S4 composite, the CNTs/NiCo2S4 composite electrode material exhibited excellent supercapacitive performance, such as a high specific capacitance up to 1537 F/g (discharge current density of 1 A/g) and an outstanding rate capability of 78.1% retention as the discharge current density increased to 100 A/g. It is therefore expected to be a promising alternative material in the area of energy storage.

Facile synthesis of hybrid CNTs/NiCo2S4 composite for high performance supercapacitors.

Science.gov (United States)

Li, Delong; Gong, Youning; Pan, Chunxu

2016-07-11

In this work, a novel carbon nanotubes (CNTs)/NiCo2S4 composite for high performance supercapacitors was prepared via a simple chemical bath deposition combined with a post-anion exchange reaction. The morphologies and phase structures of the composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS) and low-temperature sorption of nitrogen (BET). The electro-chemical tests revealed that the CNT/NiCo2S4 composite exhibited high electrochemical performance, because the CNTs were used as a conductive network for the NiCo2S4 hexagonal nanoplates. Compared with pure NiCo2S4 and the mechanically mixed CNTs/NiCo2S4 composite, the CNTs/NiCo2S4 composite electrode material exhibited excellent supercapacitive performance, such as a high specific capacitance up to 1537 F/g (discharge current density of 1 A/g) and an outstanding rate capability of 78.1% retention as the discharge current density increased to 100 A/g. It is therefore expected to be a promising alternative material in the area of energy storage.

A two-step hydrothermal synthesis approach to synthesize NiCo2S4/NiS hollow nanospheres for high-performance asymmetric supercapacitors

Science.gov (United States)

Xu, Rui; Lin, Jianming; Wu, Jihuai; Huang, Miaoliang; Fan, Leqing; He, Xin; Wang, Yiting; Xu, Zedong

2017-11-01

In this work, a high-performance asymmetric supercapacitor device based on NiCo2S4/NiS hollow nanospheres as the positive electrode and the porous activated carbon as the negative electrode was successfully fabricated via a facile two-step hydrothermal synthesis approach. This NiCo2S4/NiS//activated carbon asymmetric supercapacitor achieved a high energy density of 43.7 Wh kg-1 at a power density of 160 W kg-1, an encouraging specific capacitance of 123 F g-1 at a current density of 1 mA cm-2, as well as a long-term performance with capacitance degradation of 5.2% after 3000 consecutive cycles at 1 mA cm-2. Moreover, the NiCo2S4/NiS electrode also demonstrated an excellent specific capacitance (1947.5 F g-1 at 3 mA cm-2) and an outstanding cycling stability (retaining 90.3% after 1000 cycles). The remarkable electrochemical performances may be attributed to the effect of NiS doping on NiCo2S4 which could enlarge the surface area and increase the surface roughness.

[In situ diffuse reflectance FTIR spectroscopy study of CO adsorption on Ni2P/mesoporous molecule sieve catalysts].

Science.gov (United States)

Liu, Qian-qian; Ji, Sheng-fu; Wu, Ping-yi; Hu, Lin-hua; Huang, Xiao-fan; Zhu, Ji-qin; Li, Cheng-yue

2009-05-01

Abstract The supported nickel phosphate precursors were prepared by incipient wetness impregnation using nickel nitrate as nickel source, diammonium hydrogen phosphate as phosphorus source, and MCM-41, MCM-48, SBA-15 and SBA-16 as supports, respectively. Then, the supported Ni2 P catalysts were prepared by temperature-programmed reduction in flowing Hz from their nickel phosphate precursors. The in situ diffuse reflectance FTIR spectroscopy (DRIFTS) analysis with the probe molecule CO was carried out to characterize the surface properties. The results indicated that there were significant differences in the spectral features of the samples. The upsilon(CO) absorbances observed for adsorbed CO on mesoporous molecule sieve was attributed to weak physical adsorption. There are four different kinds of upsilon(CO) absorbances observed for adsorbed CO on Ni2 P/MCM-41 catalyst with the following assignments: (1) the formation of Ni(CO)4 at 2055 cm(-1). (2) CO terminally bonded to cus Ni(delta+) (0CO terminally bonded to Ni+ sites at 2127 cm(-1). (4) CO terminally bonded to P and form P==C==O between 2198 and 2202 cm(-1). There are two different kinds of upsilon(CO) absorbances observed for adsorbed CO on Ni2P/MCM-48, Ni2P/ SBA-15 and Ni2P/SBA-16 catalysts. The absorbance observed at 2051-2055 cm(-1) for CO adsorption on Ni2P/MCM-48, Ni2P/SBA-15 and Ni2P/SBA-16 catalysts is due to the formation of Ni(CO)4 species. The other upsilon absorbances observed at 2093-2096 cm(-1) was attributed to CO terminally bonded to cus Ni(delta+) (0

Nanostructural origin of semiconductivity and large magnetoresistance in epitaxial NiCo2O4/Al2O3 thin films

Science.gov (United States)

Zhen, Congmian; Zhang, XiaoZhe; Wei, Wengang; Guo, Wenzhe; Pant, Ankit; Xu, Xiaoshan; Shen, Jian; Ma, Li; Hou, Denglu

2018-04-01

Despite low resistivity (~1 mΩ cm), metallic electrical transport has not been commonly observed in inverse spinel NiCo2O4, except in certain epitaxial thin films. Previous studies have stressed the effect of valence mixing and the degree of spinel inversion on the electrical conduction of NiCo2O4 films. In this work, we studied the effect of nanostructural disorder by comparing the NiCo2O4 epitaxial films grown on MgAl2O4 (1 1 1) and on Al2O3 (0 0 1) substrates. Although the optimal growth conditions are similar for the NiCo2O4 (1 1 1)/MgAl2O4 (1 1 1) and the NiCo2O4 (1 1 1)/Al2O3 (0 0 1) films, they show metallic and semiconducting electrical transport, respectively. Post-growth annealing decreases the resistivity of NiCo2O4 (1 1 1)/Al2O3 (0 0 1) films, but the annealed films are still semiconducting. While the semiconductivity and the large magnetoresistance in NiCo2O4 (1 1 1)/Al2O3 (0 0 1) films cannot be accounted for in terms of non-optimal valence mixing and spinel inversion, the presence of anti-phase boundaries between nano-sized crystallites, generated by the structural mismatch between NiCo2O4 and Al2O3, may explain all the experimental observations in this work. These results reveal nanostructural disorder as being another key factor for controlling the electrical transport of NiCo2O4, with potentially large magnetoresistance for spintronics applications.

Highly active Ni/Y-doped ZrO{sub 2} catalysts for CO{sub 2} methanation

Energy Technology Data Exchange (ETDEWEB)

Takano, H., E-mail: takano_hi@hitachizosen.co.jp [Hitachi Zosen Corporation, Kashiwa, 277-8515 (Japan); Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, 060-8628 (Japan); Kirihata, Y.; Izumiya, K.; Kumagai, N. [Hitachi Zosen Corporation, Kashiwa, 277-8515 (Japan); Habazaki, H., E-mail: habazaki@eng.hokudai.ac.jp [Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, 060-8628 (Japan); Division of Applied Chemistry & Frontier Chemistry Center, Faculty of Engineering, Hokkaido University, Sapporo, 060-8628 (Japan); Hashimoto, K. [Tohoku Institute of Technology, Sendai, 277-8515 (Japan)

2016-12-01

Highlights: • The Ni/Y-doped ZrO{sub 2} catalysts show highly catalytic activity for CO{sub 2} methanation. • Bidentate carbonate is a major adsorption spice on the Ni/Y-doped ZrO{sub 2} catalysts. • The oxide support of t-ZrO{sub 2} and/or c-ZrO{sub 2} with oxygen vacancies plays a key role. - Abstract: The catalytic methanation of CO{sub 2} was carried out on Ni catalysts supported on Y-doped ZrO{sub 2} with various Y{sup 3+} concentrations and Ni/(Zr + Y) molar ratio = 1. The catalysts were characterized by X-ray diffraction, scanning transmission electron microscopy, specific surface area, temperature-programmed desorption of CO{sub 2}, and temperature-programmed reaction. In addition, operando diffuse-reflectance infrared Fourier-transform spectroscopy (DRIFT) was used to identify the adsorbed reaction intermediate. Catalysts supported on Y-doped ZrO{sub 2} show higher catalytic activity than the catalyst on Y-free ZrO{sub 2} with a monoclinic ZrO{sub 2} phase. The catalytic activity is also dependent upon the Y{sup 3+} concentration, and the highest activity was obtained for the catalyst with a Y/(Zr + Y) molar ratio of 0.333, which consists mainly of fcc Ni and cubic ZrO{sub 2} phase. Y{sup 3+} doping into ZrO{sub 2} introduces oxygen vacancies, which play an important role in enhancing the catalytic activity. The operando DRIFT study reveals that a CO adsorption intermediate is absent, and bidentate carbonate is an important intermediate for CH{sub 4} formation.

Synthesis of NiCo{sub 2}O{sub 4} nanostructures with different morphologies for the removal of methyl orange

Energy Technology Data Exchange (ETDEWEB)

Tian, Yaxi; Li, Haizhen; Ruan, Zhongyuan; Cui, Guijia; Yan, Shiqiang, E-mail: yansq@lzu.edu.cn

2017-01-30

Highlights: • Magnetic materials NiCo{sub 2}O{sub 4} with six different morphologies were successfully synthesized by a facile method. • Adsorption capacity strongly depends on the morphology. • It could be easily recovered from solution. - Abstract: Aiming to investigate the adsorption removal performance of NiCo{sub 2}O{sub 4} as water purification adsorbents, magnetic materials NiCo{sub 2}O{sub 4} with six different morphologies were successfully synthesized by a facile method. NiCo{sub 2}O{sub 4} with six different morphologies were characterized by scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, N{sub 2} adsorption-desorption, vibrating sample magnetometry and X-ray energy dispersive spectrometry. In this study, we mainly explored the effect of specific surface area, pore volume and pore size on the performance for the removal of methyl orange, and the adsorption capacity followed an order of (b) NiCo{sub 2}O{sub 4} nanorods > (e) balsam-like NiCo{sub 2}O{sub 4} > (f) rose-like NiCo{sub 2}O{sub 4} > (d) NiCo{sub 2}O{sub 4} nanoribbons > (a) NiCo{sub 2}O{sub 4} flowerlike nanostructures > (c) dandelion-like NiCo{sub 2}O{sub 4} spheres. The results indicated that NiCo{sub 2}O{sub 4} nanorods exhibited better adsorption performance. The reasons for the excellent adsorption capacity of NiCo{sub 2}O{sub 4} nanorods were also discussed in depth by analyzing scale and surface characteristics. Besides, NiCo{sub 2}O{sub 4} could be easily recovered from solution, which may avoid potential secondary pollution. Moreover, adsorption kinetics, the influence of pH and adsorption mechanism were comprehensively investigated. This finding indicated that NiCo{sub 2}O{sub 4} were promising adsorbents for water purification.

Poly(o-phenylenediamine)/NiCoFe{sub 2}O{sub 4} nanocomposites: Synthesis, characterization, magnetic and dielectric properties

Energy Technology Data Exchange (ETDEWEB)

Kannapiran, Nagarajan [PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India); Muthusamy, Athianna, E-mail: muthusrkv@gmail.com [PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India); Chitra, Palanisamy; Anand, Siddeswaran [PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India); Jayaprakash, Rajan [Nanotechnology Laboratory, Department of Physics, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India)

2017-02-01

In this study, poly(o-phenylenediamine) (PoPD)/NiCoFe{sub 2}O{sub 4} nanocomposites were synthesized by in-situ oxidative chemical polymerization method with different amount of NiCoFe{sub 2}O{sub 4} nanoparticles. The NiCoFe{sub 2}O{sub 4} nanoparticles were prepared by auto-combustion method. The structural, morphological, thermal properties of the synthesized PoPD/NiCoFe{sub 2}O{sub 4} nanocomposites were characterized by fourier transform infrared spectrum (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Magnetic properties of NiCoFe{sub 2}O{sub 4} nanoparticles and PoPD/NiCoFe{sub 2}O{sub 4} nanocomposites were studied by vibrating sample magnetometer (VSM). The FTIR and XRD techniques were used to confirm the formation of PoPD/NiCoFe{sub 2}O{sub 4} nanocomposites. The average crystalline size of NiCoFe{sub 2}O{sub 4} nanoparticles and PoPD/NiCoFe{sub 2}O{sub 4} nanocomposites were calculated from XRD. From the SEM analysis, spherical morphology of the PoPD was confirmed. The TGA results showed that the NiCoFe{sub 2}O{sub 4} nanoparticles have improved the thermal stability of PoPD. Dielectric properties of PoPD/NiCoFe{sub 2}O{sub 4} nanocomposites at different temperatures have been carried in the frequency range 50 Hz to 5 MHz. - Highlights: • Auto-combustion method was support to achieve less particle size. • Green synthesis of PoPD and nanocomposites by in-situ oxidative chemical polymerization method. • For the first time, PoPD incorporated with NiCoFe{sub 2}O{sub 4} nanoparticles. • Ferrite content affects the magnetic and dielectric properties of the nanocomposites.

Electrical transport properties of large, individual NiCo{sub 2}O{sub 4} nanoplates

Energy Technology Data Exchange (ETDEWEB)

Hu, Linfeng; Wu, Limin; Hu, Xinhua; Fang, Xiaosheng [Department of Materials Science, Fudan University, Shanghai (China); Liao, Meiyong [Optical and Electronic Materials Unit, National Institute for Materials Science (NIMS), Namiki, Tsukuba, Ibaraki (Japan)

2012-03-07

Understanding the electrical transport properties of individual semiconductor nanostructures is crucial to advancing their practical applications in high-performance nanodevices. Large-sized individual nanostructures with smooth surfaces are preferred because they can be easily made into nanodevices using conventional photolithography procedures rather than having to rely on costly and complex electron-beam lithography techniques. In this study, micrometer-sized NiCo{sub 2}O{sub 4} nanoplates are successfully prepared from their corresponding hydroxide precursor using a quasi-topotactic transformation. The Co/Ni atomic arrangement shows no changes during the transformation from the rhombohedral LDH precursor (space group R anti 3 m) to the cubic NiCo{sub 2}O{sub 4} spinel (space group Fd anti 3 m), and the nanoplate retains its initial morphology during the conversion process. In particular, electrical transport within an individual NiCo{sub 2}O{sub 4} nanoplate is further investigated. The mechanisms of electrical conduction in the low-temperature range (T < 100 K) can be explained in terms of the Mott's variable-range hopping model. At high temperatures (T > 100 K), both the variable-range hopping and nearest-neighbor hopping mechanisms contribute to the electrical transport properties of the NiCo{sub 2}O{sub 4} nanoplate. These initial results will be useful to understanding the fundamental characteristics of these nanoplates and to designing functional nanodevices from NiCo{sub 2}O{sub 4} nanostructures. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Ni-Nanocluster Modified Black TiO2 with Dual Active Sites for Selective Photocatalytic CO2 Reduction.

Science.gov (United States)

Billo, Tadesse; Fu, Fang-Yu; Raghunath, Putikam; Shown, Indrajit; Chen, Wei-Fu; Lien, Hsiang-Ting; Shen, Tzu-Hsien; Lee, Jyh-Fu; Chan, Ting-Shan; Huang, Kuo-You; Wu, Chih-I; Lin, M C; Hwang, Jih-Shang; Lee, Chih-Hao; Chen, Li-Chyong; Chen, Kuei-Hsien

2018-01-01

One of the key challenges in artificial photosynthesis is to design a photocatalyst that can bind and activate the CO 2 molecule with the smallest possible activation energy and produce selective hydrocarbon products. In this contribution, a combined experimental and computational study on Ni-nanocluster loaded black TiO 2 (Ni/TiO 2[Vo] ) with built-in dual active sites for selective photocatalytic CO 2 conversion is reported. The findings reveal that the synergistic effects of deliberately induced Ni nanoclusters and oxygen vacancies provide (1) energetically stable CO 2 binding sites with the lowest activation energy (0.08 eV), (2) highly reactive sites, (3) a fast electron transfer pathway, and (4) enhanced light harvesting by lowering the bandgap. The Ni/TiO 2[Vo] photocatalyst has demonstrated highly selective and enhanced photocatalytic activity of more than 18 times higher solar fuel production than the commercial TiO 2 (P-25). An insight into the mechanisms of interfacial charge transfer and product formation is explored. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of Molybdenum on the Corrosion Behavior of High-Entropy Alloys CoCrFeNi2 and CoCrFeNi2Mo0.25 under Sodium Chloride Aqueous Conditions

Directory of Open Access Journals (Sweden)

Alvaro A. Rodriguez

2018-01-01

Full Text Available The corrosion behavior of high-entropy alloys (HEAs CoCrFeNi2 and CoCrFeNi2Mo0.25 was investigated in 3.5 wt. percent sodium chloride (NaCl at 25°C by electrochemical methods. Their corrosion parameters were compared to those of HASTELLOY® C-276 (UNS N10276 and stainless steel 316L (UNS 31600 to assess the suitability of HEAs for potential industrial applications in NaCl simulating seawater type environments. The corrosion rates were calculated using corrosion current determined from electrochemical experiments for each of the alloys. In addition, potentiodynamic polarization measurements can indicate active, passive, and transpassive behavior of the metal as well as potential susceptibility to pitting corrosion. Cyclic voltammetry (CV can confirm the alloy susceptibility to pitting corrosion. Electrochemical impedance spectroscopy (EIS elucidates the corrosion mechanism under studied conditions. The results of the electrochemical experiments and scanning electron microscopy (SEM analyses of the corroded surfaces revealed general corrosion on alloy CoCrFeNi2Mo0.25 and HASTELLOY C-276 and pitting corrosion on alloy CoCrFeNi2 and stainless steel 316L.

How easy is CO2 fixation by M-C bond containing complexes (M = Cu, Ni, Co, Rh, Ir)?

KAUST Repository

Nolan, Steve; Cavallo, Luigi; Poater, Albert; Vummaleti, Sai V. C.; Talarico, Giovanni

2015-01-01

A comparison between different M–C bonds (M = Cu(I), Ni(II), Co(I), Rh(I) and Ir(I)) has been reported by using density functional theory (DFT) calculations to explore the role of the metal in the fixation or incorporation of CO2 into such complexes. The systems investigated are various metal based congeners of the Ir-complex 8 [(cod)(IiPr)Ir-CCPh], with a ligand scaffold based on cod and IiPr ligands (cod = 1,5-cyclooctadiene; IiPr = 1,3-bis(isopropyl)imidazol-2-ylidene). The results of this study show that the calculated CO2 insertion barriers follow the trend: Cu(I) (20.8 kcal mol−1) < Rh(I) (30.0 kcal mol−1) < Co(I) (31.3 kcal mol−1) < Ir(I) (37.5 kcal mol−1) < Ni(II) (45.4 kcal mol−1), indicating that the Cu(I) based analogue is the best CO2 fixer, while Ni(II) is the worst in the studied series.

How easy is CO2 fixation by M-C bond containing complexes (M = Cu, Ni, Co, Rh, Ir)?

KAUST Repository

Nolan, Steve

2015-11-27

A comparison between different M–C bonds (M = Cu(I), Ni(II), Co(I), Rh(I) and Ir(I)) has been reported by using density functional theory (DFT) calculations to explore the role of the metal in the fixation or incorporation of CO2 into such complexes. The systems investigated are various metal based congeners of the Ir-complex 8 [(cod)(IiPr)Ir-CCPh], with a ligand scaffold based on cod and IiPr ligands (cod = 1,5-cyclooctadiene; IiPr = 1,3-bis(isopropyl)imidazol-2-ylidene). The results of this study show that the calculated CO2 insertion barriers follow the trend: Cu(I) (20.8 kcal mol−1) < Rh(I) (30.0 kcal mol−1) < Co(I) (31.3 kcal mol−1) < Ir(I) (37.5 kcal mol−1) < Ni(II) (45.4 kcal mol−1), indicating that the Cu(I) based analogue is the best CO2 fixer, while Ni(II) is the worst in the studied series.

3D hierarchical dandelion-like NiCo{sub 2}O{sub 4}/N-doped carbon/Ni foam for an effective binder-free supercapacitor electrode

Energy Technology Data Exchange (ETDEWEB)

Xu, Xiaoyang; Hong, Wei; Zhao, Huilin; Song, Yahui; Qiu, Haixia, E-mail: haixiaqiuls@163.com; Gao, Jianping

2017-01-15

In this work, the 3D hierarchical dandelion-like NiCo{sub 2}O{sub 4}/N-doped carbon/Ni foam has been developed by introducing PANI as the precursor of N-doped carbon. Meanwhile, the NiCo{sub 2}O{sub 4}/N-doped carbon/Ni foam with a novel 3D hierarchical dandelion-like structure was verified by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy, etc. In addition, the NiCo{sub 2}O{sub 4}/N-doped carbon/Ni foam was directly used as a binder-free supercapacitor electrode and its performances were investigated by cycle voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy. The results show that the obtained NiCo{sub 2}O{sub 4}/N-doped carbon/Ni foam electrode owns good electrochemical performances, such as high specific capacitance (864 F/g at 1 A/g) and good cycling stability, owing to the porous feature from its novel 3D hierarchical dandelion-like structure. - Highlights: • The 3D hierarchical dandelion-like NiCo{sub 2}O{sub 4}/N-doped carbon/Ni foam was prepared. • It can be directly used as a binder-free supercapacitor electrode. • It owns good electrochemical performances.

Self-template synthesis of yolk-shelled NiCo2O4 spheres for enhanced hybrid supercapacitors

Science.gov (United States)

Wang, Liang; Jiao, Xinyan; Liu, Peng; Ouyang, Yu; Xia, Xifeng; Lei, Wu; Hao, Qingli

2018-01-01

A self-template method is developed for hierarchically yolk-shelled NiCo2O4 spheres (YS-NiCo2O4) through a controlled hydrolysis process and followed by a thermal annealing treatment. The yolk-shelled NiCo2O4 spheres possess out-shell consisting of hundreds of ultrathin sheets with 3-5 nm in thickness and solid yolk composing of a large number of nanoparticles. The YS-NiCo2O4 generates a large specific surface area of 169.6 m2 g-1. Benefit from the large specific surface area and rich oxygen vacancy, the as-fabricated YS-NiCo2O4 as electrode materials for supercapacitor exhibits high specific capacitance of 835.7 F g-1 at 0.5 A g-1, an enhanced rate capability and excellent electrochemical stability with 93% retention after 10,000 cycles even at 10 A g-1. Moreover, a hybrid supercapacitor combined with YS-NiCo2O4 and graphene shows a high energy density of 34.7 Wh kg-1 at the power density of 395.0 W kg-1 at 0.5 A g-1, even at 20 A g-1, the hybrid supercapacitor still delivers the energy density of about 12.1 Wh kg-1 and the power density of 11697 W kg-1. The desirable performance of yolk-shelled NiCo2O4 suggests it to be a promising material as supercapacitor electrodes.

Is NiCo2S4 really a semiconductor?

KAUST Repository

Xia, Chuan; Li, Peng; Gandi, Appala; Schwingenschlö gl, Udo; Alshareef, Husam N.

2015-01-01

NiCo2S4 is a technologically important electrode material that has recently achieved remarkable performance in pseu-docapacitor, catalysis, and dye-synthesized solar cell applications.[1-5] Essentially, all reports on this material have pre

Flexible and High Performance Supercapacitors Based on NiCo2O4for Wide Temperature Range Applications

Science.gov (United States)

Gupta, Ram K.; Candler, John; Palchoudhury, Soubantika; Ramasamy, Karthik; Gupta, Bipin Kumar

2015-10-01

Binder free nanostructured NiCo2O4 were grown using a facile hydrothermal technique. X-ray diffraction patterns confirmed the phase purity of NiCo2O4. The surface morphology and microstructure of the NiCo2O4 analyzed by scanning electron microscopy (SEM) showed flower-like morphology composed of needle-like structures. The potential application of binder free NiCo2O4 as an electrode for supercapacitor devices was investigated using electrochemical methods. The cyclic voltammograms of NiCo2O4 electrode using alkaline aqueous electrolytes showed the presence of redox peaks suggesting pseudocapacitance behavior. Quasi-solid state supercapacitor device fabricated by sandwiching two NiCo2O4 electrodes and separating them by ion transporting layer. The performance of the device was tested using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The device showed excellent flexibility and cyclic stability. The temperature dependent charge storage capacity was measured for their variable temperature applications. Specific capacitance of the device was enhanced by ~150% on raising the temperature from 20 to 60 °C. Hence, the results suggest that NiCo2O4 grown under these conditions could be a suitable material for high performance supercapacitor devices that can be operated at variable temperatures.

Syngas Production from Catalytic CO2 Reforming of CH4 over CaFe2O4 Supported Ni and Co Catalysts: Full Factorial Design Screening

Directory of Open Access Journals (Sweden)

M. Anwar Hossain

2018-01-01

Full Text Available In this study, the potential of dry reforming reaction over CaFe2O4 supported Ni and Co catalysts were investigated. The Co/CaFe2O4 and Ni/CaFe2O4 catalysts were synthesized using wet impregnation method by varying the metal loading from 5-15 %. The synthesized catalysts were tested in methane dry reforming reaction at atmospheric pressure and reaction temperature ranged 700-800 oC. The catalytic performance of the catalysts based on the initial screening is ranked as 5%Co/CaFe2O4 < 10%Co/CaFe2O4 < 5%Ni/CaFe2O4 < 10%Ni/CaFe2O4 according to their performance. The Ni/CaFe2O4 catalyst was selected for further investigation using full factorial design of experiment. The interaction effects of three factors namely metal loading (5-15 %, feed ratio (0.4-1.0, and reaction temperature (700-800 oC were evaluated on the catalytic activity in terms of CH4 and CO2 conversion as well as H2 and CO yield. The interaction between the factors showed significant effects on the catalyst performance at metal loading, feed ratio and reaction temperature of 15 %, 1.0, and 800 oC. respectively. The 15 wt% Ni/CaFe2O4 was subsequently characterized by Thermogravimetric (TGA, X-ray Diffraction (XRD, Field Emission Scanning Electron Microscopy (FESEM, Energy Dispersive X-ray Spectroscopy (EDX, X-ray Photoelectron Spectroscopy (XPS, N2-physisorption, Temperature Programmed Desorption (TPD-NH3, TPD-CO2, and Fourier Transform Infra Red (FTIR to ascertain its physiochemical properties.  This study demonstrated that the CaFe2O4 supported Ni catalyst has a good potential to be used for syngas production via methane dry reforming. Copyright © 2018 BCREC Group. All rights reserved Received: 5th May 2017; Revised: 8th August 2017; Accepted: 9th August 2017; Available online: 22nd January 2018; Published regularly: 2nd April 2018 How to Cite: Hossain, M.A., Ayodele, B.V., Cheng, C.K., Khan, M.R. (2018. Syngas Production from Catalytic CO2 Reforming of CH4 over CaFe2O4 Supported

NiCo2S4 nanowires array as an efficient bifunctional electrocatalyst for full water splitting with superior activity

Science.gov (United States)

Liu, Danni; Lu, Qun; Luo, Yonglan; Sun, Xuping; Asiri, Abdullah M.

2015-09-01

The present communication reports the topotactic conversion of NiCo2O4 nanowires array on carbon cloth (NiCo2O4 NA/CC) into NiCo2S4 NA/CC, which is used as an efficient bifunctional electrocatalyst for water splitting with good durability and superior activity in 1.0 M KOH. This NiCo2S4 NA/CC electrode produces 100 mA cm-2 at an overpotential of 305 mV for hydrogen evolution and 100 mA cm-2 at an overpotential of 340 mV for oxygen evolution. To afford a 10 mA cm-2 water-splitting current, the alkaline water electrolyzer made from NiCo2S4 NA/CC needs a cell voltage of 1.68 V, which is 300 mV less than that for NiCo2O4 NA/CC, and has good stability.The present communication reports the topotactic conversion of NiCo2O4 nanowires array on carbon cloth (NiCo2O4 NA/CC) into NiCo2S4 NA/CC, which is used as an efficient bifunctional electrocatalyst for water splitting with good durability and superior activity in 1.0 M KOH. This NiCo2S4 NA/CC electrode produces 100 mA cm-2 at an overpotential of 305 mV for hydrogen evolution and 100 mA cm-2 at an overpotential of 340 mV for oxygen evolution. To afford a 10 mA cm-2 water-splitting current, the alkaline water electrolyzer made from NiCo2S4 NA/CC needs a cell voltage of 1.68 V, which is 300 mV less than that for NiCo2O4 NA/CC, and has good stability. Electronic supplementary information (ESI) available: Experimental section and ESI Figures. See DOI: 10.1039/c5nr04064g

Effect of Ni/Al2O3-SiO2 and Ni/Al2O3-SiO2 with K2O Promoter Catalysts on H2, CO and CH4 Concentration by CO2 Gasification of Rosa Multiflora Biomass

Directory of Open Access Journals (Sweden)

Tursunov Obid

2017-11-01

Full Text Available The thermal behaviour of the Rosa mutiflora biomass by thermogravimetric analysis was studied at heating rate 3 K min−1 from ambient temperature to 950 °C. TGA tests were performed in high purity carbon dioxide (99 998% with a flow rate 200 ml/min and 100 mg of sample, milled and sieved to a particle size below 250 µm. Moreover, yields of gasification products such as hydrogen (H2, carbon monoxide (CO and methane (CH4 were determined based on the thermovolumetric measurements of catalytic (Ni/Al2O3-SiO2 and Ni/Al2O3-SiO2 with K2O promoter catalysts and non-catalytic gasification of the Rosa multiflora biomass. Additionally, carbon conversion degrees are presented. Calculations were made of the kinetic parameters of carbon monoxide and hydrogen formation reaction in the catalytic and non-catalytic CO2 gasification processes. A high temperature of 950 °C along with Ni/Al2O3-SiO2and Ni/Al2O3-SiO2 with K2O promoter catalysts resulted in a higher conversion of Rosa multiflora biomass into gaseous yield production with greatly increasing of H2 and CO contents. Consequently, H2 and CO are the key factors to produce renewable energy and bio-gases (synthesis gas. The parameters obtained during the experimental examinations enable a tentative assessment of plant biomasses for the process of large-scale gasification in industrial sectors.

Structural and compositional optimization of the LiNi0.8Co0.2O2 electrode by new synthesis conditions

International Nuclear Information System (INIS)

Mosqueda L, Y.; Milian P, C. R.; Pomares A, M.; Rodriguez H, J.; Perez C, E.

2012-01-01

The optimization of citrate precursor method to obtain the LiNi 0.8 Co 0.2 O 2 oxide from the thermal decomposition of the citrate precursor (NH 4 ) 3 LiNi 0.8 Co 0.2 (C 6 H 5 O 7 ) is presented. The optimization procedure consists of both the lithium atmosphere and the reaction time control during the decomposition of the citrate precursor. Were obtained and characterized two kind of the (Li l-x Ni x )(Ni 0.8 Co 0.2 )O 2 oxides, with and without optimized synthesis conditions, identified as A and B oxides, respectively. The A and B oxides are characterized by compositional, structural and electrochemical studies. The results showed that is possible to reach the ordered oxide phase at smaller reaction time if the lithium atmosphere is controlled. From the combination of the chemical analysis by Icp and the DRX Rietveld structural refinement it is possible to establish the Li, Ni(II), Ni(III) and Co(III) composition with great accuracy. The resulted structural and compositional transformations have a close relation with technological parameters of the rechargeable lithium battery using Li Ni 0.8 Co 0.2 O 2 oxide as cathode. (Author)

Two-step hydrothermal synthesis of NiCo2S4/Co9S8 nanorods on nickel foam for high energy density asymmetric supercapacitors

Science.gov (United States)

Xu, Rui; Lin, Jianming; Wu, Jihuai; Huang, Miaoliang; Fan, Leqing; Chen, Hongwei; He, Xin; Wang, Yiting; Xu, Zedong

2018-03-01

It is still a huge challenge to obtain a high-energy-density asymmetric supercapacitors and develop an active electrode material with excellent electrochemical characteristics. Although NiCo2S4 has been considered as one of the promising positive electrode materials for asymmetric supercapacitors, the electrochemical performance of the NiCo2S4-based positive electrodes is still relatively low and cannot meet the demand in the devices. Herein, NiCo2S4/Co9S8 nanorods with a large capacitance are synthesized via a simple two-step hydrothermal treatment. A high-performance asymmetric supercapacitor operating at 1.6 V is successfully assembled using the NiCo2S4/Co9S8 nanorods as positive electrode and activated carbon as negative electrode in 3 M KOH aqueous electrolyte, which demonstrates a fairly high energy density of 49.6 Wh kg-1 at a power density of 123 W kg-1, an excellent capacitance of 0.91 F cm-2 (139.42 F g-1) at current density of 1 mA cm-2 as well as a remarkable cycling stability due to the high physical strength, the large specific surface area, and the good conductivity for NiCo2S4/Co9S8 nanorods and the brilliant synergistic effect for NiCo2S4 and Co9S8 electrode materials. The as-prepared NiCo2S4/Co9S8 nanorods open up a new platform as positive electrode material for high-energy-density asymmetric supercapacitors in energy-storage.

Hydrogenated CoOx nanowire@Ni(OH)2 nanosheet core-shell nanostructures for high-performance asymmetric supercapacitors

Science.gov (United States)

Zhu, Jianxiao; Huang, Lei; Xiao, Yuxiu; Shen, Leo; Chen, Qi; Shi, Wangzhou

2014-05-01

We report a facile strategy to prepare 3D core-shell nanowire heterostructures with microporous hydrogenated CoOx (H-CoOx) nanowires as the conducting scaffold to support Ni(OH)2 nanosheets. Benefiting from the H-CoOx nanowire core to provide the effective pathway for charge transport and the core-shell heterostructures with synergistic effects, the H-CoOx@Ni(OH)2 core-shell nanowire electrode achieved the specific capacitance of 2196 F g-1 (areal capacitance of 5.73 F cm-2), which is approximately a 1.4-fold enhancement compared with the Co3O4@Ni(OH)2 core-shell nanowires. An aqueous asymmetric supercapacitor (ASC) device was fabricated by using H-CoOx@Ni(OH)2 nanowires as the positive electrode and reduced graphene oxide @Fe3O4 nanocomposites as the negative electrode. The ASCs achieved high energy density (~45.3 W h kg-1 at 1010 W kg-1), high power density (~7080 W kg-1 at 23.4 W h kg-1) and high cycling stability. Furthermore, after charging for ~1 min, one such 22 cm2 ASC device demonstrated to be able to drive a small windmill (0.8 V, 0.1 W) for 20 min. Two such ASCs connected in series can power up a seven-color LED (3.2 V) efficiently.We report a facile strategy to prepare 3D core-shell nanowire heterostructures with microporous hydrogenated CoOx (H-CoOx) nanowires as the conducting scaffold to support Ni(OH)2 nanosheets. Benefiting from the H-CoOx nanowire core to provide the effective pathway for charge transport and the core-shell heterostructures with synergistic effects, the H-CoOx@Ni(OH)2 core-shell nanowire electrode achieved the specific capacitance of 2196 F g-1 (areal capacitance of 5.73 F cm-2), which is approximately a 1.4-fold enhancement compared with the Co3O4@Ni(OH)2 core-shell nanowires. An aqueous asymmetric supercapacitor (ASC) device was fabricated by using H-CoOx@Ni(OH)2 nanowires as the positive electrode and reduced graphene oxide @Fe3O4 nanocomposites as the negative electrode. The ASCs achieved high energy density (~45.3 W h kg-1 at

In situ synthesis of 3D CoS nanoflake/Ni(OH)_2 nanosheet nanocomposite structure as a candidate supercapacitor electrode

International Nuclear Information System (INIS)

Li, Songzhan; Wen, Jian; Chen, Tian; Xiong, Liangbin; Wang, Jianbo; Fang, Guojia

2016-01-01

A three-dimensional (3D) CoS/Ni(OH)_2 nanocomposite structure based on CoS nanoflakes and two-dimensional (2D) Ni(OH)_2 nanosheets were in situ synthesized on Ni foam by a whole hydrothermal reaction and electrodeposition process. The 3D CoS/Ni(OH)_2 nanocomposite structures demonstrate the combined advantages of a sustained cycle stability of CoS and high specific capacitance from Ni(OH)_2. The obtained CoS/Ni(OH)_2 nanocomposite structures on Ni foam can directly serve as a binder-free electrode for a supercapacitor. For the 3D CoS/Ni(OH)_2 nanocomposite electrode, the high specific capacitance is 1837 F g"−"1 at a scan rate of 1 mV s"−"1, which is obviously higher than both the bare CoS electrode and Ni(OH)_2 electrode. The galvanostatic charge and discharge measurements illustrate that the 3D CoS/Ni(OH)_2 nanocomposite electrode possesses excellent cycle stability, and it keeps a 95.8% retention of the initial capacity after 5000 cycles. Electrochemical impedance spectroscopy measurements also confirm that the 3D CoS/Ni(OH)_2 nanocomposite electrode has better electrochemical characteristics. These remarkable performances can be attributed to the unique 3D nanoporous structure of CoS/Ni(OH)_2 which leads to a large accessible surface area and a high stability during long-term operation. In addition, 2D Ni(OH)_2 nanosheets in 3D nanocomposite structures can afford rapid mass transport and a strong synergistic effect of CoS and Ni(OH)_2 as individual compositions contribute to the high performance of the nanocomposite structure electrode. These results may promote the design and implementation of nanocomposite structures in advanced supercapacitors. (paper)

Enhanced cycling stability of NiCo2S4@NiO core-shell nanowire arrays for all-solid-state asymmetric supercapacitors

Science.gov (United States)

Huang, Yuanyuan; Shi, Tielin; Jiang, Shulan; Cheng, Siyi; Tao, Xiangxu; Zhong, Yan; Liao, Guanglan; Tang, Zirong

2016-12-01

As a new class of pseudocapacitive material, metal sulfides possess high electrochemical performance. However, their cycling performance as conventional electrodes is rather poor for practical applications. In this article, we report an original composite electrode based on NiCo2S4@NiO core-shell nanowire arrays (NWAs) with enhanced cycling stability. This three-dimensional electrode also has a high specific capacitance of 12.2 F cm-2 at the current density of 1 mA cm-2 and excellent cycling stability (about 89% retention after 10,000 cycles). Moreover, an all-solid-state asymmetric supercapacitor (ASC) device has been assembled with NiCo2S4@NiO NWAs as the positive electrode and active carbon (AC) as the negative electrode, delivering a high energy density of 30.38 W h kg-1 at 0.288 KW kg-1 and good cycling stability (about 109% retention after 5000 cycles). The results show that NiCo2S4@NiO NWAs are promising for high-performance supercapacitors with stable cycling based on the unique core-shell structure and well-designed combinations.

Hierarchical core-shell NiCo2O4@NiMoO4 nanowires grown on carbon cloth as integrated electrode for high-performance supercapacitors

Science.gov (United States)

Huang, Liang; Zhang, Wei; Xiang, Jinwei; Xu, Henghui; Li, Guolong; Huang, Yunhui

2016-08-01

Hierarchical core-shell NiCo2O4@NiMoO4 nanowires were grown on carbon cloth (CC@NiCo2O4@NiMoO4) by a two-step hydrothermal route to fabricate a flexible binder-free electrode. The prepared CC@NiCo2O4@NiMoO4 integrated electrode was directly used as an electrode for faradaic supercapacitor. It shows a high areal capacitance of 2.917 F cm-2 at 2 mA cm-2 and excellent cycling stability with 90.6% retention over 2000 cycles at a high current density of 20 mA cm-2. The superior specific capacitance, rate and cycling performance can be ascribed to the fast transferring path for electrons and ions, synergic effect and the stability of the hierarchical core-shell structure.

The facile synthesis of hierarchical NiCoO2 nanotubes comprised ultrathin nanosheets for supercapacitors

Science.gov (United States)

Xu, Xin; Zhou, Han; Ding, Shujiang; Li, Jun; Li, Beibei; Yu, Demei

2014-12-01

Hierarchical NiCoO2 nanosheets nanotubes are successfully prepared by a mild solution method based on the template of polymeric nanotubes (PNT) followed by a thermal annealing treatment. The microstructure and chemical composition of NiCoO2 nanosheets nanotubes are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analyzer, X-ray diffraction (XRD) and Thermogravimetric analysis (TGA). When evaluated as an electrode material for supercapacitors, the results of electrochemical test show that the unique NiCoO2 nanosheets nanotubes exhibit relatively high specific capacitance of 1468, 1352, 1233, 1178, 1020 and 672 F g-1 at the discharge current densities of 2, 4, 8, 10, 20 and 40 A g-1, respectively. They also reveal an excellent cycling stability of 99.2% retention after 3000 cycles at 10 A g-1. The smart nanostructures of the NiCoO2 nanosheets nanotubes make a prominent contribution to the excellent electrochemical performance.

Hierarchical MoS2 nanowires/NiCo2O4 nanosheets supported on Ni foam for high-performance asymmetric supercapacitors

Science.gov (United States)

Wen, Shiyang; Liu, Yu; Zhu, Fangfang; Shao, Rong; Xu, Wei

2018-01-01

The hierarchical MoS2 nanowires/NiCo2O4 nanosheets (MS/NCO) supercapacitor electrode materials supported on Ni foam were synthesized by a two-step hydrothermal method. The capacitance was investigated by using various electrochemical methods including cyclic voltammetry, constant-current galvanostatic charge/discharge curves and electrochemical impedance spectroscopy. The MS/NCO networks show 7 times more capacitance (7.1 F cm-2) than pure NiCo2O4 nanosheets by CV at a scan rate of 2 mV s-1. The specific capacitance of the assembled MS/NCO//active carbon (AC) asymmetric supercapacitor could reach up to 51.7 F g-1 at a current density of 1.5 A g-1. Also, the maximum energy density of 18.4 W h kg-1 at a power density of 1200.2 W kg-1 was achieved, with 98.2% specific capacitance retention after 8000 cycles. These exciting results exhibit potential application in developing energy storage devices with high energy density and high power density.

Microstructure and Wear Resistance of Laser-Clad (Co, Ni61.2B26.2Si7.8Ta4.8 Coatings

Directory of Open Access Journals (Sweden)

Luan Zhang

2017-10-01

Full Text Available It has been reported that a quaternary Co61.2B26.2Si7.8Ta4.8 alloy is a good glass former and can be laser-clad to an amorphous composite coating with superior hardness and wear resistance. In this paper, alloys with varying Ni contents to substitute for Co are coated on the surface of #45 carbon steel using a 5-kW CO2 laser source for the purpose of obtaining protective coatings. In contrast to the quaternary case, the clad layers are characterized by a matrix of α-(Fe, Co, Ni solid solution plus CoB, Co3B, and Co3Ta types of precipitates. The cladding layer is divided into four regions: Near-surface dendrites, α-(Fe, Co, Ni solid solution plus dispersed particles in the middle zone, columnar bonding zone, and heat-affected area that consists of martensite. The hardness gradually decreases with increasing Ni content, and the maximum hardness occurs in the middle zone. Both the friction coefficient and wear volume are minimized in the alloy containing 12.2% Ni. Compared with the previous cobalt-based quaternary alloy Co61.2B26.2Si7.8Ta4.8, the addition of the Ni element reduces the glass-forming ability and henceforth the hardness and wear resistance of the clad layers.

The solubility of Ni in molten Li{sub 2}CO{sub 3}-Na{sub 2}CO{sub 3} (52/48) in H{sub 2}/H{sub 2}O/CO{sub 2} atmosphere

Energy Technology Data Exchange (ETDEWEB)

Boden, Andreas; Lindbergh, Goeran [KTH Chemical Science and Engineering, Department of Chemical Engineering and Technology, SE-100 44 Stockholm (Sweden); Yoshikawa, Masahiro [Central Research Institute of Electric Power Industry, Sector, Energy Conversion Engineering, Energy Engineering Research Laboratory, Yokosuka-shi, Kanagawa 240-0196 (Japan)

2007-03-30

In this work the solubility of a Ni-Al anode for MCFC has been studied at atmospheric pressure and two different temperatures using various gas compositions containing H{sub 2}/H{sub 2}O/CO{sub 2}. It is well known that nickel is dissolved at cathode conditions in an MCFC. However, the results in this study show that nickel can be dissolved also at the anode, indicating that the solubility increases with increasing CO{sub 2} partial pressure of the inlet gas and decreasing with increasing temperature. This agrees with the results found by other authors concerning the solubility of NiO at cathode conditions. The dissolution of Ni into the melt can proceed in two ways, either by the reduction of water or by the reduction of carbon dioxide. (author)

Heterobimetallic [NiFe] Complexes Containing Mixed CO/CN- Ligands: Analogs of the Active Site of the [NiFe] Hydrogenases.

Science.gov (United States)

Perotto, Carlo U; Sodipo, Charlene L; Jones, Graham J; Tidey, Jeremiah P; Blake, Alexander J; Lewis, William; Davies, E Stephen; McMaster, Jonathan; Schröder, Martin

2018-03-05

The development of synthetic analogs of the active sites of [NiFe] hydrogenases remains challenging, and, in spite of the number of complexes featuring a [NiFe] center, those featuring CO and CN - ligands at the Fe center are under-represented. We report herein the synthesis of three bimetallic [NiFe] complexes [Ni( N 2 S 2 )Fe(CO) 2 (CN) 2 ], [Ni( S 4 )Fe(CO) 2 (CN) 2 ], and [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] that each contain a Ni center that bridges through two thiolato S donors to a {Fe(CO) 2 (CN) 2 } unit. X-ray crystallographic studies on [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ], supported by DFT calculations, are consistent with a solid-state structure containing distinct molecules in the singlet ( S = 0) and triplet ( S = 1) states. Each cluster exhibits irreversible reduction processes between -1.45 and -1.67 V vs Fc + /Fc and [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] possesses a reversible oxidation process at 0.17 V vs Fc + /Fc. Spectroelectrochemical infrared (IR) and electron paramagnetic resonance (EPR) studies, supported by density functional theory (DFT) calculations, are consistent with a Ni III Fe II formulation for [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] + . The singly occupied molecular orbital (SOMO) in [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] + is based on Ni 3d z 2 and 3p S with the S contributions deriving principally from the apical S-donor. The nature of the SOMO corresponds to that proposed for the Ni-C state of the [NiFe] hydrogenases for which a Ni III Fe II formulation has also been proposed. A comparison of the experimental structures, and the electrochemical and spectroscopic properties of [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] and its [Ni( N 2 S 3 )] precursor, together with calculations on the oxidized [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] + and [Ni( N 2 S 3 )] + forms suggests that the binding of the {Fe(CO)(CN) 2 } unit to the {Ni(CysS) 4 } center at the active site of the [NiFe] hydrogenases suppresses thiolate-based oxidative chemistry involving the bridging thiolate S donors

Formation of NiCo{sub 2}V{sub 2}O{sub 8} yolk-double shell spheres with enhanced lithium storage properties

Energy Technology Data Exchange (ETDEWEB)

Lu, Yan; Nai, Jianwei; Lou, Xiong Wen David [School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore (Singapore)

2018-03-05

Complex nanostructures with multi-components and intricate architectures hold great potential in developing high-performance electrode materials for lithium-ion batteries (LIBs). Herein, we demonstrate a facile self-templating strategy for the synthesis of metal vanadate nanomaterials with complex chemical composition of NiCo{sub 2}V{sub 2}O{sub 8} and a unique yolk-double shell structure. Starting with the Ni-Co glycerate spheres, NiCo{sub 2}V{sub 2}O{sub 8} yolk-double shell spheres are synthesized through an anion-exchange reaction of Ni-Co glycerate templates with VO{sub 3}{sup -} ions, followed by an annealing treatment. By virtue of compositional and structural advantages, these NiCo{sub 2}V{sub 2}O{sub 8} yolk-double shell spheres manifest outstanding lithium storage properties when evaluated as anodes for LIBs. Impressively, an extra-high reversible capacity of 1228 mAh g{sup -1} can be retained after 500 cycles at a high current density of 1.0 Ag{sup -1}. (copyright 2018 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Mechanistic Study of Ni/CeO{sub 2}-catalyzed CO{sub 2}/CH{sub 4} Reaction Using Flow and Static Methods

Energy Technology Data Exchange (ETDEWEB)

Kang, Jin-Gyu; Roh, Joong-Seok; Kim, Ji-Yeong; Lee, Sung-Han; Choi, Jonng-Gill [Yonsei University, Seoul (Korea, Republic of)

2016-08-15

Ni/CeO{sub 2} catalysts with different Ni loadings (5, 7, 10, 12, and 14 wt% Ni) were prepared by an impregnation method and examined for the CO{sub 2} reforming of methane using flow and static reactors. Their catalytic activities and selectivities were measured under CO{sub 2}/CH{sub 4}/Ar (=5/5/40 cm{sup 3}/min) flow at 450-800 .deg. C using a flow reactor system with an on-line gas chromatography. At flexed temperature, the CO{sub 2} and CH{sub 4} conversions varied only slightly with the Ni wt%, whereas the H{sub 2}/CO ratio increased with increasing Ni wt%. The conversions increased with temperature, reaching 98% at 800 .deg. C. The H{sub 2}/CO ratio varied with temperature in the range of 450-800 .deg. C, from less than 1 below 550 .deg. C to close to 1 at 550-600 .deg. C and then back to less than 1 above 600 .deg. C. The apparent activation energies were determined to be 43.1 kJ/mol for the CO{sub 2} consumption and 50.2 kJ/mol for the CH{sub 4} consumption based on the rates measured for the reforming reaction over 5 wt% Ni/CeO{sub 2} catalyst at 550-750 .deg. C. Additionally, the catalytic reforming reaction at low pressure (40 Torr) was investigated by a static reactor system by using a differential photoacoustic cell, in which the rates were measured from the CO{sub 2} photoacoustic signal data at early reaction times over the temperature range of 460-610 .deg. C. Apparent activation energies of 25.5-30.1 kJ/mol were calculated from the CO{sub 2} disappearance rates. The CO{sub 2} adsorption on the Ni/CeO{sub 2} catalyst was investigated by the CO{sub 2} photoacoustic spectroscopy and Fourier transform infrared spectroscopy. Feasible side reactions during the catalytic CO{sub 2}/CH{sub 4} reaction were suggested on the basis of the kinetic and spectroscopic results.

Low Resistance Ohmic Contacts to Bi[sub 2]Te[sub 3] Using Ni and Co Metallization

KAUST Repository

Gupta, Rahul P.; Xiong, K.; White, J. B.; Cho, Kyeongjae; Alshareef, Husam N.; Gnade, B. E.

2010-01-01

A detailed study of the impact of surface preparation and postdeposition annealing on contact resistivity for sputtered Ni and Co contacts to thin-film Bi2 Te3 is presented. The specific contact resistivity is obtained using the transfer length method. It is observed that in situ sputter cleaning using Ar bombardment before metal deposition gives a surface free of oxides and other contaminants. This surface treatment reduces the contact resistivity by more than 10 times for both Ni and Co contacts. Postdeposition annealing at 100°C on samples that were sputter-cleaned further reduces the contact resistivity to < 10-7 cm2 for both Ni and Co contacts to Bi2 Te3. Co as a suitable contact metal to Bi2 Te3 is reported. Co provided similar contact resistance values as Ni, but had better adhesion and less diffusion into the thermoelectric material, making it a suitable candidate for contact metallization to Bi2 Te3 based devices. © 2010 The Electrochemical Society.

Low Resistance Ohmic Contacts to Bi[sub 2]Te[sub 3] Using Ni and Co Metallization

KAUST Repository

Gupta, Rahul P.

2010-04-27

A detailed study of the impact of surface preparation and postdeposition annealing on contact resistivity for sputtered Ni and Co contacts to thin-film Bi2 Te3 is presented. The specific contact resistivity is obtained using the transfer length method. It is observed that in situ sputter cleaning using Ar bombardment before metal deposition gives a surface free of oxides and other contaminants. This surface treatment reduces the contact resistivity by more than 10 times for both Ni and Co contacts. Postdeposition annealing at 100°C on samples that were sputter-cleaned further reduces the contact resistivity to < 10-7 cm2 for both Ni and Co contacts to Bi2 Te3. Co as a suitable contact metal to Bi2 Te3 is reported. Co provided similar contact resistance values as Ni, but had better adhesion and less diffusion into the thermoelectric material, making it a suitable candidate for contact metallization to Bi2 Te3 based devices. © 2010 The Electrochemical Society.

A circular dichroism sensor for Ni{sup 2+} and Co{sup 2+} based on L-cysteine capped cadmium sulfide quantum dots

Energy Technology Data Exchange (ETDEWEB)

Tedsana, Wimonsiri [Materials Chemistry Research Center, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Tuntulani, Thawatchai [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Ngeontae, Wittaya, E-mail: wittayange@kku.ac.th [Materials Chemistry Research Center, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand)

2015-03-31

Highlights: • Demonstrated a new efficient sensor platform based quantum dots. • Used chiral quantum dots as CD sensor for the detection of heavy metal ions for the first time. • The proposed CD sensor showed highest selectivity towards Ni{sup 2+} and Co{sup 2+}. • Low detection limits of 7.33 μM and 1.13 μM for Ni{sup 2+} and Co{sup 2+}, respectively. • Can be used in real water samples comparing with ICP-OES. - Abstract: A new circular dichroism sensor for detecting Ni{sup 2+} and Co{sup 2+} was proposed for the first time using chiral chelating quantum dots. The detection principle was based on changing of circular dichroism signals of the chiral quantum dots when forming a chiral complex with Ni{sup 2+} or Co{sup 2+}. L-Cysteine capped cadmium sulfide quantum dots (L-Cyst-CdS QDs) were proposed as a chiral probe. The CD spectrum of L-Cyst-CdS QDs was significantly changed in the presence of Ni{sup 2+} and Co{sup 2+}. On the other hand, other studied cations did not alter the original CD spectrum. Moreover, when increasing the concentration of Ni{sup 2+} or Co{sup 2+}, the intensity of the CD spectrum linearly increased as a function of concentration and could be useful for the quantitative analysis. The proposed CD sensor showed linear working concentration ranges of 10–60 μM and 4–80 μM with low detection limits of 7.33 μM and 1.13 μM for the detection of Ni{sup 2+} and Co{sup 2+}, respectively. Parameters possibly affected the detection sensitivity such as solution pH and incubation time were studied and optimized. The proposed sensor was applied to detect Ni{sup 2+} and Co{sup 2+} in real water samples, and the results agreed well with the analysis using the standard ICP-OES.

Shape-controlled synthesis of NiCo2S4 and their charge storage characteristics in supercapacitors

Science.gov (United States)

Zhang, Yufei; Ma, Mingze; Yang, Jun; Sun, Chencheng; Su, Haiquan; Huang, Wei; Dong, Xiaochen

2014-07-01

In this work, a facile hydrothermal approach for the shape-controlled synthesis of NiCo2S4 architectures is reported. Four different morphologies, urchin-, tube-, flower-, and cubic-like NiCo2S4 microstructures, have been successfully synthesized by employing various solvents. The obtained precursors and products have been characterized by X-ray diffraction, field-emission scanning electron microscopy and transmission electron microscopy. It is revealed that the supersaturation of nucleation and crystal growth is determined by the solvent polarity and solubility, which can precisely control the morphology of NiCo2S4 microstructures. The detailed electrochemical performances of the various NiCo2S4 microstructures are investigated by cyclic voltammetry and galvanostatic charge-discharge measurements. The results indicate that the tube-like NiCo2S4 exhibits promising capacitive properties with high capacitance and excellent retention. Its specific capacitance can reach 1048 F g-1 at the current density of 3.0 A g-1 and 75.9% of its initial capacitance is maintained at the current density of 10.0 A g-1 after 5000 charge-discharge cycles.

Inkjet Printing as High-Throughput Technique for the Fabrication of NiCo2O4 Films

Directory of Open Access Journals (Sweden)

Reyna Dianela Bacelis-Martínez

2017-01-01

Full Text Available Owing to its distinctive physicochemical properties, nickel-cobalt mixed oxide (NiCo2O4 has become a promising and innovative material for applications in many technological fields. The design of fast and reliable techniques for the deposition of this material is essential in the development of applications. In this work, NiCo2O4 films were successfully prepared by an inkjet printing technique using a suitable ink obtained from metal nitrates in a glycerol-water mixture. In order to deposit well-defined and uniform film patterns, the instrumental parameters such as drop spacing and inkjet voltage have been explored. The pure crystalline bimetallic nickel cobaltite oxide is obtained at 500°C with a homogeneous compositional distribution along the film. The average thickness observed by scanning electron microscopy is around 490 nm, whereas X-ray photoelectron spectroscopy analysis revealed that the film surface presents mixed oxidation states for both metals: Co2+, Co3+, Ni2+, and Ni3+. The electrocatalytic performance of inkjet-printed NiCo2O4 films for the water oxidation reaction is comparable with earlier reports.

Unusual Co moment reduction in the NiCoO/Co exchange bias system

Energy Technology Data Exchange (ETDEWEB)

Brueck, S. [Max-Planck-Institut fuer Metallforschung, Heisenbergstrasse 3, D-70569 Stuttgart (Germany)]. E-mail: brueck@mf.mpg.de; Goering, E. [Max-Planck-Institut fuer Metallforschung, Heisenbergstrasse 3, D-70569 Stuttgart (Germany); Tang, Y.J. [Center for Magnetic Recording Research, University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0401 (United States); Schuetz, G. [Max-Planck-Institut fuer Metallforschung, Heisenbergstrasse 3, D-70569 Stuttgart (Germany); Berkowitz, A.E. [Center for Magnetic Recording Research, University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0401 (United States); Department of Physics, University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0401 (United States)

2007-03-15

To answer the question on how the explicit mechanism of coupling in the antiferromagnetic alloy NiCoO is established when in close contact to a ferromagnetic Co layer, X-ray magnetic circular dichroism (XMCD) measurements have been performed. Precise XMCD spectra at the L{sub 2,3}-edge of Ni as well as Co have been obtained at room temperature and at 80K by measuring total electron yield X-ray absorption spectra. The Ni XMCD clearly shows the existence of free, rotatable magnetic Ni moments in the antiferromagnet. As for the Co, XMCD at room temperature shows an average magnetic moment comparable to bulk values. Cooling the sample to 80K decreases the average Co moment by 10%. This decrease is explained by a reduction of ferromagnetic cobalt moments related to antiferromagnetic coupling or pinning close to the interface.

CO{sub 2} reforming of CH{sub 4} over stabilized mesoporous Ni-CaO-ZrO{sub 2} composites

Energy Technology Data Exchange (ETDEWEB)

Shuigang Liu; Lianxiu Guan; Junping Li; Ning Zhao; Wei Wei; Yuhan Sun [Chinese Academy of Sciences, Taiyuan (China). State Key Laboratory of Coal Conversion

2008-09-15

Mesoporous Ni-CaO-ZrO{sub 2} nanocomposites with high thermal stability were designed and employed in the CO{sub 2}/CH{sub 4} reforming. The nanocomposites with appropriate Ni/Ca/Zr molar ratios exhibited excellent activity and prominent coking resistivity. The Ni crystallites were effectively controlled under the critical size for coke formation in such nanocomposites. It was found that low Ni content resulted in high metal dispersion and good catalytic performance. Moreover, the basicity of the matrices improved the chemisorption of CO{sub 2} and promoted the gasification of deposited coke on the catalyst. 33 refs., 5 figs., 1 tab.

Magnetism and superconductivity in CeFe2-xTxAs2 (T = Co and Ni) single crystals

International Nuclear Information System (INIS)

Thamizhavel, A.

2010-01-01

Single crystals of pure and transition metal doped CaFe 2- x T x As 2 (T = Co and Ni) have been grown by flux method using molten Sn as solvent. The magnetic and superconducting properties of the grown crystals were studied by measuring the electrical resistivity, magnetic susceptibility and neutron diffraction measurements. A spin density wave (SDW)/structural transition is observed at 170 K for the pure CaFe 2 As 2 single crystal and it gets suppressed with T (Co and Ni) doping. For an optimum dopant concentration of x = 0.06, the sample becomes superconducting. From the detailed studies on CaFe 2- x Ni x As 2 single crystals we have constructed a magnetic phase diagram. (author)

Isothermal sections of the Co-Ni-Ti system at 950 and 1 000 C

Energy Technology Data Exchange (ETDEWEB)

Li, Han; Jin, Zhanpeng [Central South Univ., Changsha (China). School of Materials Science and Engineering; Zhou, Peng [Hunan Univ. of Science and Technology, Xiangtan (China). Hunan Provincial Key Defense Lab. of High Temperature Wear Resisting Materials and Preparation Technology; Du, Yong [Central South Univ., Changsha (China). State Key Lab. of Powder Metallurgy

2018-02-15

The isothermal sections of the Co-Ni-Ti system at 950 and 1000 C were investigated experimentally. Diffusion couples were measured by electron probe microanalysis to construct the phase relations at 950 C, whereas eleven key alloys annealed at 1000 C were investigated using X-ray diffraction and electron probe microanalysis. The ternary phase, τ-(Co,Ni){sub 3}Ti (hP24-VCo{sub 3}), was observed at both temperatures. At 950 C, continuous solid solutions are formed between CoTi{sub 2} and NiTi{sub 2} as well as between CoTi and NiTi. Eight 3-phase regions, i. e. Ni{sub 3}Ti + (Co,Ni)Ti + τ, Ni{sub 3}Ti + γ-(Co,Ni) + τ, τ + c-Co{sub 2}Ti + (Co,Ni)Ti, τ + c-Co{sub 2}Ti + Co{sub 3}Ti, τ + Co{sub 3}Ti + γ-(Co,Ni), c-Co{sub 2}Ti + h-Co{sub 2}Ti + Co{sub 3}Ti, L + β-(Ti) + (Co,Ni)Ti{sub 2} and L + (Co,Ni)Ti{sub 2} + (Co,Ni)Ti, were constructed at 1000 C. Considerable ternary solubilities in Ni{sub 3}Ti, Co{sub 3}Ti and c-Co{sub 2}Ti were determined.

Facile synthesis of CoNi2S4/Co9S8 composites as advanced electrode materials for supercapacitors

Science.gov (United States)

Zhao, Fenglin; Huang, Wanxia; Zhang, Hongtao; Zhou, Dengmei

2017-12-01

In this paper, a facile chemical bath deposition method was utilized to synthesize three-dimensional nanostructured CoNi2S4/Co9S8 (CNSCS) composites as advanced electrode materials for high performance supercapacitors. CNSCS composites showed remarkable electrochemical performance owing to the high porosity, appropriate pore size distribution, novel architecture and synergistic effect of Ni/Co ions. The electrochemical tests revealed that CNSCS composites exhibited high specific capacitance (1183.3 Fg-1 at the current density of 2 Ag-1), excellent rate performance (74.9% retention with tenfold current density increase) and outstanding cycle life stability. Moreover, the effect of temperature on electrochemical performance of CNSCS composites was investigated and the results indicated the specific capacitance of CoNi2S4/Co9S8 can keep relatively stable in a wide temperature from 0 °C to 50 °C. These results indicated that the synthesized CNSCS composites can be a promising electrode materials candidate for supercapacitors and chemical bath deposition is a promising processing route for CNSCS composites production.

Studies on solid solutions based on layered honeycomb-ordered phases P2-Na{sub 2}M{sub 2}TeO{sub 6} (M=Co, Ni, Zn)

Energy Technology Data Exchange (ETDEWEB)

Berthelot, Romain; Schmidt, Whitney; Sleight, A.W. [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States); Subramanian, M.A., E-mail: mas.subramanian@oregonstate.edu [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States)

2012-12-15

Three complete solid solutions between the layered phases P2-Na{sub 2}M{sub 2}TeO{sub 6} (M=Co, Ni, Zn) have been prepared by conventional solid state method and investigated through X-ray diffraction, magnetism and optical measurements. All compositions are characterized by a M{sup 2+}/X{sup 6+} honeycomb ordering within the slabs and crystallize in a hexagonal unit cell. However, a structural transition based on a different stacking is observed as nickel (space group P6{sub 3}/mcm) is substituted by zinc or cobalt (space group P6{sub 3}22). All compositions exhibit a paramagnetic Curie-Weiss behavior at high temperatures; and the magnetic moment values confirm the presence of Ni{sup 2+} and/or Co{sup 2+} cations. The low-temperature antiferromagnetic order of Na{sub 2}Ni{sub 2}TeO{sub 6} and Na{sub 2}Co{sub 2}TeO{sub 6} is suppressed by zinc substitution. The color of the obtained compositions varies from pink, to light green and white when M=Co, Ni, Zn, respectively. - Graphical abstract: The comparison between the structure of Na{sub 2}Ni{sub 2}TeO{sub 6} (left) and Na{sub 2}M{sub 2}TeO{sub 6} (M=Co, Zn) (right) evidences the stacking difference with distinct atom sequences along the hexagonal c-axis. Highlights: Black-Right-Pointing-Pointer Solid solutions between lamellar phases Na{sub 2}M{sub 2}TeO{sub 6} (M=Co, Ni, Zn) are investigated. Black-Right-Pointing-Pointer A M{sup 2+}/X{sup 6+} honeycomb ordering characterized all the compositions. Black-Right-Pointing-Pointer A structural transition is shown when Ni is replaced by Co or Zn. Black-Right-Pointing-Pointer The low-temperature AFM ordering of Na{sub 2}Ni{sub 2}TeO{sub 6} and Na{sub 2}Co{sub 2}TeO{sub 6} is suppressed by zinc substitution. Black-Right-Pointing-Pointer Color changes from pink to light green and white when M=Co, Ni, Zn, respectively.

In situ growth of NiCo(2)S(4) nanosheets on graphene for high-performance supercapacitors.

Science.gov (United States)

Peng, Shengjie; Li, Linlin; Li, Chengchao; Tan, Huiteng; Cai, Ren; Yu, Hong; Mhaisalkar, Subodh; Srinivasan, Madhavi; Ramakrishna, Seeram; Yan, Qingyu

2013-10-03

We demonstrate a facile hydrothermal method for growth of ultrathin NiCo2S4 nanosheets on reduced graphene oxide (RGO), which exhibit remarkable electrochemical performance with higher capacitance and longer cycle life than the bare NiCo2S4 hollow spheres (HSs).

Pb3O4 type antimony oxides MSb2O4 (M = Co, Ni) as anode for Li-ion batteries

International Nuclear Information System (INIS)

Jibin, A.K.; Reddy, M.V.; Subba Rao, G.V.; Varadaraju, U.V.; Chowdari, B.V.R.

2012-01-01

Graphical abstract: Isostructural Pb 3 O 4 type MSb 2 O 4 (M = Co, Ni) compounds were investigated as possible anodes for lithium ion batteries. The reversible capacity is due to electrochemically active Sb and the transition metal and Li 2 O form an inactive matrix which buffers volume variations associated with alloying-de-alloying of antimony. Highlights: ► Isostructural MSb 2 O 4 (M = Co, Ni) were studied as anode for LIBs for first time. ► Li/MSb 2 O 4 (M = Co, Ni) cells displayed reversibility due to electrochemically active Sb. ► CoSb 2 O 4 showed good reversibility compared to NiSb 2 O 4 . - Abstract: Polycrystalline samples of isostructural MSb 2 O 4 (M = Co, Ni) have been prepared by solid state synthesis and lithium-storage is investigated as possible anode materials for lithium-ion batteries. The reaction mechanism of lithium with MSb 2 O 4 (M = Co, Ni) is explored by galvanostatic cycling, cyclic voltammogram and ex situ studies. Both CoSb 2 O 4 and NiSb 2 O 4 exhibit similar electrochemical behavior and show reversible capacity of 490 and 412 mAh g −1 respectively in the first cycle. Reversible alloying de-alloying of Li x Sb takes place in an amorphous matrix of M (Co, Ni) and Li 2 O during electrochemical cycling.

Nickel Nanowire@Porous NiCo2O4 Nanorods Arrays Grown on Nickel Foam as Efficient Pseudocapacitor Electrode

Directory of Open Access Journals (Sweden)

Houzhao Wan

2017-12-01

Full Text Available A three dimensional hierarchical nanostructure composed of nickel nanowires and porous NiCo2O4 nanorods arrays on the surface of nickel foam is successfully fabricated by a facile route. In this structure, the nickel nanowires are used as core materials to support high-pseudocapacitance NiCo2O4 nanorods and construct the well-defined NiCo2O4 nanorods shell/nickel nanowires core hierarchical structure on nickel foam. Benefiting from the participation of nickel nanowires, the nickel nanowire@NiCo2O4/Ni foam electrode shows a high areal specific capacitance (7.4 F cm−2 at 5 mA cm−2, excellent rate capability (88.04% retained at 100 mA cm−2, and good cycling stability (74.08% retained after 1,500 cycles. The superior electrochemical properties made it promising as electrode for supercapacitors.

Study of the structural and thermal stability of Li0.3Co2/3Ni1/6Mn1/6O2

International Nuclear Information System (INIS)

Mahmoud, Abdelfattah; Saadoune, Ismael; Difi, Siham; Sougrati, Moulay Tahar; Lippens, Pierre-Emmanuel; Amarilla, José Manuel

2014-01-01

Thermal and structural stabilities of the delithiated positive electrode material Li x Co 2/3 Ni 1/6 Mn 1/6 O 2 were studied by X-ray diffraction, magnetic and thermogravimetric analysis. In the opposite to the classical electrode materials LiNiO 2 and LiCoO 2 , the structural symmetry (S.G. R-3 m) of the starting material LiCo 2/3 Ni 1/6 Mn 1/6 O 2 is preserved during the electrochemical cycling with a small variation of the unit cell parameters. Squid measurements evidenced that practically no Ni 2+ ions were present in the lithium slab even after the lithium extraction process. For the thermal stability, the highly oxidized phase Li 0.3 Co 2/3 Ni 1/6 Mn 1/6 O 2 was tested. This delithiated phase undergoes only 5.16% weight loss after heating up to 600 °C. This weight loss has no effect on the structure symmetry as the starting α-NaFeO 2 type structure was preserved during the thermal treatment. The obtained results coupled to the excellent electrochemical features of LiCo 2/3 Ni 1/6 Mn 1/6 O 2 clearly showits ability to compete with the commercialized cathode materials

Magnetic ordering of Hf{sub 3}Ni{sub 2}Si{sub 3}-type {Sm, Tb, Er}{sub 3}Co{sub 2}Ge{sub 3} and {Tb, Ho}{sub 3}Ni{sub 2}Ge{sub 3} compounds

Energy Technology Data Exchange (ETDEWEB)

Morozkin, A.V., E-mail: morozkin@tech.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, Moscow, GSP-1, 119991 (Russian Federation); Yapaskurt, V.O. [Department of Petrology, Geological Faculty Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Nirmala, R. [Indian Institute of Technology Madras, Chennai 600036 (India); Quezado, S.; Malik, S.K. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59082-970 (Brazil); Mozharivskyj, Y. [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1 (Canada); Isnard, O. [CNRS, Institut. Néel, 25 rue des Martyrs BP166 x, F-38042 Grenoble (France); Université Grenoble Alpes, Inst. Néel, F-38042 Grenoble (France)

2017-02-15

The magnetic ordering of Hf{sub 3}Ni{sub 2}Si{sub 3}-type {Sm, Tb, Er}{sub 3}Co{sub 2}Ge{sub 3} and {Tb, Ho}{sub 3}Ni{sub 2}Ge{sub 3} compounds (space group Cmcm, oC32) was investigated via magnetization measurements and neutron diffraction study in a zero-applied field. {Sm, Tb, Er}{sub 3}Co{sub 2}Ge{sub 3} and Ho{sub 3}Ni{sub 2}Ge{sub 3} exhibit field sensitive complex antiferromagnetic orderings with T{sub N}=51 K, T{sub m}=10 K for Sm{sub 3}Co{sub 2}Ge{sub 3}, T{sub N}=34 K, T{sub m}=13 K for Tb{sub 3}Co{sub 2}Ge{sub 3}, T{sub N}=7 K for Er{sub 3}Co{sub 2}Ge{sub 3} and T{sub N}=11 K for Ho{sub 3}Ni{sub 2}Ge{sub 3}. At 2 K and above the critical field of ~5 kOe, 20 kOe, 4 kOe and 7 kOe for Sm{sub 3}Co{sub 2}Ge{sub 3}, Tb{sub 3}Co{sub 2}Ge{sub 3}, Er{sub 3}Co{sub 2}Ge{sub 3} and Ho{sub 3}Ni{sub 2}Ge{sub 3}, respectively, saturation magnetizations per rare-earth atom are 6.5 μ{sub B} for Tb{sub 3}Co{sub 2}Ge{sub 3}, 7.0 μ{sub B} for Er{sub 3}Co{sub 2}Ge{sub 3} and 8.0 μ{sub B} for Ho{sub 3}Ni{sub 2}Ge{sub 3} in the field of 140 kOe, whereas magnetization of Sm{sub 3}Co{sub 2}Ge{sub 3} has an antiferromagnetic behaviour. The isothermal magnetic entropy change, ΔS{sub m}, indicates a field-induced ferromagnetic ordering in Sm{sub 3}Co{sub 2}Ge{sub 3}, Tb{sub 3}Co{sub 2}Ge3, Er{sub 3}Co{sub 2}Ge{sub 3} and Ho{sub 3}Ni{sub 2}Ge{sub 3} with a maximal ΔS{sub m} value of −10.9 J/kg K for Ho{sub 3}Ni{sub 2}Ge{sub 3} at 11 K for a field change of 50 kOe. In a zero-applied magnetic field, below T{sub N}=33 K and down to T{sub m}{sup ND}=15 K Tb{sub 3}Ni{sub 2}Ge{sub 3} shows an ac-antiferromagnetic ordering with the C2′/c magnetic space group, a K{sub 0}=[0, 0, 0] propagation vector and a a{sub Tb3Ni2Ge3}×b{sub Tb3Ni2Ge3}×c{sub Tb3Ni2Ge3} magnetic unit cell. Below T{sub m}{sup ND}=15 K, its magnetic structure is a sum of the ac-antiferromagnetic component with the C2′/c magnetic space group of the K{sub 0} vector and a sine-modulated a

Phase purity of NiCo2O4, a catalyst candidate for electrolysis of water

Science.gov (United States)

Singer, J.; Fielder, W. L.; Garlick, R. G.; Negas, T.

1987-01-01

NiCo2O4 is shown to be difficult to obtain as a pure phase, and may never have been so obtained. High resolution x-ray diffractometry is required for its precise characterization. Film XRD is not likely to show the asymmetry in the spinel diffraction lines, caused by poorly crystallized NiO, as seen in diffractometer traces. The Co3O4 which is expected to accompany NiO as an impurity in NiCo2O4 syntheses has the same diffraction pattern as the binary oxide. Firings of the co-precipitated hydroxides at 300, 350, and 400 C, including one in pure O2, failed to produce single phase cobaltate. Scanning electron microscopy showed all the sintered products to range over several orders of magnitude in agglomerate/particle size. Surface areas by BET were all in the range 40 to 110 m sq/g, equivalent to particles of 200 to 100 Angstrom diameter. The spinel diffraction line breadths were compatible with those approximate dimensions.

Facile synthesis of single-crystal mesoporous CoNiO2 nanosheets assembled flowers as anode materials for lithium-ion batteries

International Nuclear Information System (INIS)

Liu, Yanguo; Zhao, Yanyan; Yu, Yanlong; Ahmad, Mashkoor; Sun, Hongyu

2014-01-01

Highlights: • Mesoporous CoNiO 2 microflowers have been synthesized. • Li-ion batteries performance of CoNiO 2 has been investigated. • CoNiO 2 structure delivers high capacity, good cycling stability and high rate capability. • The electrochemical performance is attributed to the mesoporous nature and the 3D structure. • CoNiO 2 can be considered to be an attractive candidate as an electrode material for LIBs. - Abstract: Mesoporous CoNiO 2 microflowers assembled with single-crystal nanosheets were successfully synthesized by a hydrothermal method and subsequent annealing process and their lithium storage capacity were investigated. The structural and compositional analysis of the mesoporous CoNiO 2 microflowers has been studied by X-ray diffraction, field emission scanning electron microscopy and high-resolution transmission electron microscopy. The Bruauer–Emmett–Teller specific surface area of CoNiO 2 microflowers has been calculated by the nitrogen isotherm curve and pore size distribution has been determined by the Barret–Joyner–Halenda method. It has been found that the as-prepared CoNiO 2 electrodes delivered satisfied capacity, good cycling stability and rate capability. The improved electrochemical performance is attributed to the mesoporous nature and the 3D assembled structure. Therefore, such a structure can be considered to be an attractive candidate as an electrode material for lithium-ion batteries

Preparation of metastable CoFeNi alloys with ultra-high magnetic saturation (Bs = 2.4-2.59 T) by reverse pulse electrodeposition

Science.gov (United States)

Tabakovic, Ibro; Venkatasamy, Venkatram

2018-04-01

The results of reverse pulse electrodeposition of CoFeNi films with ultra-high magnetic saturation, i.e. Bs values between 2.4 and 2.59 T, are presented in this work. Based on valence-bond theory (Hund's rule) it was assumed that the electronic configuration of MOH obtained by one electron reduction of electroactive intermediate (MOH+ads + e → MOHads) or oxidation of metal (M - e + HOH → MOH + H+) would result with larger number of spins per atom for each of transition metals in MOH-precipitated in CoFeNi deposit- with one more spin than their respective neutral metal in the order: Fe > Co > Ni. The experimental results showed that the increase of Bs value above Slater-Pauling curve was not observed for CoFe alloys, thus FeOH and CoOH compounds were not present in deposit. However, the increase of the Bs values above the Slater-Pauling curve (Bs = 2.4-2.59 T) was observed, for CoFeNi films obtained by reverse pulse electrodeposition. Therefore, NiOH as a stable compound is probably formed in a one-electron oxidation step during anodic pulse oxidation reaction precipitated presumably at the grain boundaries, giving rise to the ultra-high magnetic saturation of CoFeNi films. The effects of experimental conditions on elemental composition, magnetic properties, crystal structure, and thermal stability of CoFeNi films were studied.

Poisoning of Ni-Based anode for proton conducting SOFC by H2S, CO2, and H2O as fuel contaminants

Science.gov (United States)

Sun, Shichen; Awadallah, Osama; Cheng, Zhe

2018-02-01

It is well known that conventional solid oxide fuel cells (SOFCs) based on oxide ion conducting electrolyte (e.g., yttria-stabilized zirconia, YSZ) and nickel (Ni) - ceramic cermet anodes are susceptible to poisoning by trace amount of hydrogen sulfide (H2S) while not significantly impacted by the presence of carbon dioxide (CO2) and moisture (H2O) in the fuel stream unless under extreme operating conditions. In comparison, the impacts of H2S, CO2, and H2O on proton-conducting SOFCs remain largely unexplored. This study aims at revealing the poisoning behaviors caused by H2S, CO2, and H2O for proton-conducting SOFCs. Anode-supported proton-conducting SOFCs with BaZe0.1Ce0.7Y0.1Yb0.1O3 (BZCYYb) electrolyte and Ni-BZCYYb anode and La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) cathode as well as Ni-BZCYYb/BZCYYb/Ni-BZCYYb anode symmetrical cells were subjected to low ppm-level H2S or low percentage-level CO2 or H2O in the hydrogen fuel, and the responses in cell electrochemical behaviors were recorded. The results suggest that, contrary to conventional SOFCs that show sulfur poisoning and CO2 and H2O tolerance, such proton-conducting SOFCs with Ni-BZCYYb cermet anode seem to be poisoned by all three types of "contaminants". Beyond that, the implications of the experimental observations on understanding the fundamental mechanism of anode hydrogen electrochemical oxidation reaction in proton conducting SOFCs are also discussed.

MAu2GeS4-Chalcogel (M = Co, Ni): Heterogeneous Intra- and Intermolecular Hydroamination Catalysts

KAUST Repository

Davaasuren, Bambar

2017-08-08

High surface area macroporous chalcogenide aerogels (chalcogels) MAu2GeS4 (M = Co, Ni) were prepared from K2Au2GeS4 precursor and Co(OAc)2 or NiCl2 by one-pot sol-gel metathesis reactions in aqueous media. The MAu2GeS4-chalcogels were screened for catalytic intramolecular hydroamination of 4-pentyn-1-amine substrate at different temperatures. 87% and 58% conversion was achieved at 100 °C, using CoAu2GeS4- and NiAu2GeS4-chalcogels respectively, and the reaction kinetics follows the first order. It was established that the catalytic performance of the aerogels is associated with the M(2+) centers present in the structure. Intermolecular hydroamination of aniline with 1-R-4-ethynylbenzene (R = -H, -OCH3, -Br, -F) was carried out at 100 °C using CoAu2GeS4-chalcogel catalyst, due to its promising catalytic performance. The CoAu2GeS4-chalcogel regioselectively converted the pair of substrates to respective Markovnikov products, (E)-1-(4-R-phenyl)-N-phenylethan-1-imine, with 38% to 60% conversion.

MAu2GeS4-Chalcogel (M = Co, Ni): Heterogeneous Intra- and Intermolecular Hydroamination Catalysts

KAUST Repository

Davaasuren, Bambar; Emwas, Abdul-Hamid M.; Rothenberger, Alexander

2017-01-01

High surface area macroporous chalcogenide aerogels (chalcogels) MAu2GeS4 (M = Co, Ni) were prepared from K2Au2GeS4 precursor and Co(OAc)2 or NiCl2 by one-pot sol-gel metathesis reactions in aqueous media. The MAu2GeS4-chalcogels were screened for catalytic intramolecular hydroamination of 4-pentyn-1-amine substrate at different temperatures. 87% and 58% conversion was achieved at 100 °C, using CoAu2GeS4- and NiAu2GeS4-chalcogels respectively, and the reaction kinetics follows the first order. It was established that the catalytic performance of the aerogels is associated with the M(2+) centers present in the structure. Intermolecular hydroamination of aniline with 1-R-4-ethynylbenzene (R = -H, -OCH3, -Br, -F) was carried out at 100 °C using CoAu2GeS4-chalcogel catalyst, due to its promising catalytic performance. The CoAu2GeS4-chalcogel regioselectively converted the pair of substrates to respective Markovnikov products, (E)-1-(4-R-phenyl)-N-phenylethan-1-imine, with 38% to 60% conversion.

Rapid synthesis of Co, Ni co-doped ZnO nanoparticles: Optical and electrochemical properties

Energy Technology Data Exchange (ETDEWEB)

Romeiro, Fernanda C.; Marinho, Juliane Z.; Lemos, Samantha C.S. [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Moura, Ana P. de [LIEC, Instituto de Química, Universidade Estadual Paulista, 14800-900 Araraquara, SP (Brazil); Freire, Poliana G. [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Silva, Luis F. da; Longo, Elson [LIEC, Instituto de Química, Universidade Estadual Paulista, 14800-900 Araraquara, SP (Brazil); Munoz, Rodrigo A.A. [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Lima, Renata C., E-mail: rclima@iqufu.ufu.br [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil)

2015-10-15

We report for the first time a rapid preparation of Zn{sub 1−2x}Co{sub x}Ni{sub x}O nanoparticles via a versatile and environmentally friendly route, microwave-assisted hydrothermal (MAH) method. The Co, Ni co-doped ZnO nanoparticles present an effect on photoluminescence and electrochemical properties, exhibiting excellent electrocatalytic performance compared to undoped ZnO sample. Photoluminescence spectroscopy measurements indicated the reduction of the green–orange–red visible emission region after adding Co and Ni ions, revealing the formation of alternative pathways for the generated recombination. The presence of these metallic ions into ZnO creates different defects, contributing to a local structural disorder, as revealed by Raman spectra. Electrochemical experiments revealed that the electrocatalytic oxidation of dopamine on ZnO attached to multi-walled carbon nanotubes improved significantly in the Co, Ni co-doped ZnO samples when compared to pure ZnO. - Graphical abstract: Rapid synthesis of Co, Ni co-doped ZnO nanoparticles: optical and electrochemical properties. Co, Ni co-doped ZnO hexagonal nanoparticles with optical and electrocatalytic properties were successfully prepared for the first time using a microwave hydrothermal method at mild conditions. - Highlights: • Co{sup 2+} and Ni{sup 2+} into ZnO lattice obtained a mild and environmentally friendly process. • The heating method strongly influences in the growth and shape of the particles. • Short-range defects generated by the ions insertion affects the photoluminescence. • Doped ZnO nanoparticles improve the electrocatalytic properties of pure oxide.

NiCo2O4-Based Supercapacitor Nanomaterials

OpenAIRE

Chenggang Wang; E Zhou; Weidong He; Xiaolong Deng; Jinzhao Huang; Meng Ding; Xianqi Wei; Xiaojing Liu; Xijin Xu

2017-01-01

In recent years, the research on supercapacitors has ushered in an explosive growth, which mainly focuses on seeking nano-/micro-materials with high energy and power densities. Herein, this review will be arranged from three aspects. We will summarize the controllable architectures of spinel NiCo2O4 fabricated by various approaches. Then, we introduce their performances as supercapacitors due to their excellent electrochemical performance, including superior electronic conductivity and electr...

Carbon Deposition during CO2 Electrolysis in Ni-Based Solid-Oxide-Cell Electrodes

DEFF Research Database (Denmark)

Skafte, Theis Løye; Graves, Christopher R.; Blennow, P.

2015-01-01

. Electrochemical impedance spectroscopy in both H2/H2O and CO/CO2 revealed an increase in resistance of the fuel electrode after each CO2 electrolysis current-voltage curve, indicating possible carbon deposition. The difference in partial oxygen pressure between inlet and outlet was analyzed to verify carbon...... in detail. In an attempt to mitigate the degradation due to carbon deposition, the Ni-YSZ electrode was infiltrated with a gadolinium doped ceria (CGO) solution. Initial results indicate that the coking tolerance was not enhanced, but it is still unclear whether infiltrated cells degrade less. However......, infiltrated cells display a significant performance enhancement before coking, especially under electrolysis current. The investigation thus indicated carbon formation in the Ni containing fuel electrode before the thermodynamically calculated threshold for average measurements of the cell was reached...

Enhanced hydrogen storage properties of MgH2 co-catalyzed with K2NiF6 and CNTs.

Science.gov (United States)

Sulaiman, N N; Ismail, M

2016-12-06

The composite of MgH 2 /K 2 NiF 6 /carbon nanotubes (CNTs) is prepared by ball milling, and its hydrogenation properties are studied for the first time. MgH 2 co-catalyzed with K 2 NiF 6 and CNTs exhibited an improvement in the onset dehydrogenation temperature and isothermal de/rehydrogenation kinetics compared with the MgH 2 -K 2 NiF 6 composite. The onset dehydrogenation temperature of MgH 2 doped with 10 wt% K 2 NiF 6 and 5 wt% CNTs is 245 °C, which demonstrated a reduction of 25 °C compared with the MgH 2 + 10 wt% K 2 NiF 6 composite. In terms of rehydrogenation kinetics, MgH 2 doped with 10 wt% K 2 NiF 6 and 5 wt% CNTs samples absorbed 3.4 wt% of hydrogen in 1 min at 320 °C, whereas the MgH 2 + 10 wt% K 2 NiF 6 sample absorbed 2.6 wt% of hydrogen under the same conditions. For dehydrogenation kinetics at 320 °C, the MgH 2 + 10 wt% K 2 NiF 6 + 5 wt% CNTs sample released 3.3 wt% hydrogen after 5 min of dehydrogenation. By contrast, MgH 2 doped with 10 wt% K 2 NiF 6 released 3.0 wt% hydrogen in the same time period. The apparent activation energy, E a , for the dehydrogenation of MgH 2 doped with 10 wt% K 2 NiF 6 reduced from 100.0 kJ mol -1 to 70.0 kJ mol -1 after MgH 2 was co-doped with 10 wt% K 2 NiF 6 and 5 wt% CNTs. Based on the experimental results, the hydrogen storage properties of the MgH 2 /K 2 NiF 6 /CNTs composite is enhanced because of the catalytic effects of the active species of KF, KH and Mg 2 Ni that are formed in situ during dehydrogenation, as well as the unique structure of CNTs.

NiCo2O4@TiN Core-shell Electrodes through Conformal Atomic Layer Deposition for All-solid-state Supercapacitors

KAUST Repository

Wang, Renqi

2016-03-04

Ternary transition metal oxides such as NiCo2O4 show great promise as supercapacitor electrode materials. However, the unsatisfactory rate performance of NiCo2O4 may prove to be a major hurdle to its commercial usage. Herein, we report the development of NiCo2O4@TiN core–shell nanostructures for all-solid-state supercapacitors with significantly enhanced rate capability. We demonstrate that a thin layer of TiN conformally grown by atomic layer deposition (ALD) on NiCo2O4 nanofiber arrays plays a key role in improving their electrical conductivity, mechanical stability, and rate performance. Fabricated using the hybrid NiCo2O4@TiN electrodes, the symmetric all-solid-state supercapacitor exhibited an impressive stack power density of 58.205 mW cm−3 at a stack energy density of 0.061 mWh cm−3. To the best of our knowledge, these values are the highest of any NiCo2O4-based all-solid-state supercapacitor reported. Additionally, the resulting NiCo2O4@TiN all-solid-state device displayed outstanding cycling stability by retaining 70% of its original capacitance after 20,000 cycles at a high current density of 10 mA cm−2. These results illustrate the promise of ALD-assisted hybrid NiCo2O4@TiN electrodes for sustainable and integrated energy storage applications.

NiCo2O4@TiN Core-shell Electrodes through Conformal Atomic Layer Deposition for All-solid-state Supercapacitors

KAUST Repository

Wang, Renqi; Xia, Chuan; Wei, Nini; Alshareef, Husam N.

2016-01-01

Ternary transition metal oxides such as NiCo2O4 show great promise as supercapacitor electrode materials. However, the unsatisfactory rate performance of NiCo2O4 may prove to be a major hurdle to its commercial usage. Herein, we report the development of NiCo2O4@TiN core–shell nanostructures for all-solid-state supercapacitors with significantly enhanced rate capability. We demonstrate that a thin layer of TiN conformally grown by atomic layer deposition (ALD) on NiCo2O4 nanofiber arrays plays a key role in improving their electrical conductivity, mechanical stability, and rate performance. Fabricated using the hybrid NiCo2O4@TiN electrodes, the symmetric all-solid-state supercapacitor exhibited an impressive stack power density of 58.205 mW cm−3 at a stack energy density of 0.061 mWh cm−3. To the best of our knowledge, these values are the highest of any NiCo2O4-based all-solid-state supercapacitor reported. Additionally, the resulting NiCo2O4@TiN all-solid-state device displayed outstanding cycling stability by retaining 70% of its original capacitance after 20,000 cycles at a high current density of 10 mA cm−2. These results illustrate the promise of ALD-assisted hybrid NiCo2O4@TiN electrodes for sustainable and integrated energy storage applications.

Tracer diffusion of 60Co and 63Ni in amorphous NiZr alloy

International Nuclear Information System (INIS)

Hoshino, K.; Averback, R.S.; Hahn, H.; Rothman, S.J.

1987-01-01

Tracer diffusion of 60 Co and 63 Ni in equiatomic amorphous NiZr alloy in the temperature range between 486 and 641 0 K can be described by: D/sub Co/sup */ = 3.7 x 10 -7 exp[-(135 +- 14) kJ mole -1 /RT] m 2 /sec and D/sub Ni//sup */ = 1.7 x 10 -7 exp[-(140 +- 9) kJ mole -1 /RT] m 2 /sec. The values of D/sub Ni//sup */ are in reasonable agreement with those measured by the Rutherford backscattering technique. The measured diffusivities were independent of time, indicating that no relaxation took place during diffusion. 27 refs., 2 tabs

Three-Dimensional NiCo2O4@MnMoO4 Core-Shell Nanoarrays for High-Performance Asymmetric Supercapacitors.

Science.gov (United States)

Yuan, Yuliang; Wang, Weicheng; Yang, Jie; Tang, Haichao; Ye, Zhizhen; Zeng, Yujia; Lu, Jianguo

2017-10-10

Design of new materials with sophisticated nanostructure has been proven to be an efficient strategy to improve their properties in many applications. Herein, we demonstrate the successful combination of high electron conductive materials of NiCo 2 O 4 with high capacitance materials of MnMoO 4 by forming a core-shell nanostructure. The NiCo 2 O 4 @MnMoO 4 core-shell nanoarrays (CSNAs) electrode possesses high capacitance of 1169 F g -1 (4.24 F cm -2 ) at a current density of 2.5 mA cm -2 , obviously larger than the pristine NiCo 2 O 4 electrode. The asymmetric supercapacitors (ASCs), assembled with NiCo 2 O 4 @MnMoO 4 CSNAs as binder-free cathode and active carbon (AC) as anode, exhibit high energy density of 15 Wh kg -1 and high power density of 6734 W kg -1 . Cycle performance of NiCo 2 O 4 @MnMoO 4 CSNAs//AC ASCs, conducted at current density of 20 mA cm -2 , remain 96.45% of the initial capacitance after 10,000 cycles, demonstrating its excellent long-term cycle stability. Kinetically decoupled analysis reveals that the capacitive capacitance is dominant in the total capacitance of NiCo 2 O 4 @MnMoO 4 CSNAs electrode, which may be the reason for ultra long cycle stability of ASCs. Our assembled button ASC can easily light up a red LED for 30 min and a green LED for 10 min after being charged for 30 s. The remarkable electrochemical performance of NiCo 2 O 4 @MnMoO 4 CSNAs//AC ASCs is attributed to its enhanced surface area, abundant electroactive sites, facile electrolyte infiltration into the 3D NiCo 2 O 4 @MnMnO 4 nanoarrays and fast electron and ion transport path.

Influence of Ni/Co molar ratio on electromagnetic properties and microwave absorption performances for Ni/Co paraffin composites

Energy Technology Data Exchange (ETDEWEB)

Yan, S.J., E-mail: shaojiuyan@126.com [Department of Structural Steel, Functional Materials and Heat Treatment Processing, AVIC Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Aviation Key Laboratory of Science and Technology on Stealth Materials, Beijing 100095 (China); Dai, S.L. [The Office of AVIC Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Ding, H.Y.; Wang, Z.Y. [Aviation Key Laboratory of Science and Technology on Stealth Materials, Beijing 100095 (China); Liu, D.B [Department of Structural Steel, Functional Materials and Heat Treatment Processing, AVIC Beijing Institute of Aeronautical Materials, Beijing 100095 (China)

2014-05-01

Ni and Co metallic microparticles with submicron size were synthesized with a simple wet chemical reduction method at a relatively low temperature. Then their morphologies and structures were characterized by SEM and XRD. Ni metallic microparticles have spherical-shape morphology with fcc crystalline structure, however, Co has a distinct leaf-like morphology with the fcc and hcp mixed phases crystalline structures. For the characterization of their electromagnetic properties, paraffin matrix composites containing different molar ratio Ni and Co mixture powder as fillers were prepared. It was found that both the electromagnetic properties and electromagnetic microwave absorption performances of absorber layer were remarkably influenced by Ni/Co molar ratio. The electromagnetic microwave absorption performances were significantly improved by blending Ni and Co metallic microparticles into paraffin matrix with changing Ni/Co molar ratio, and enhanced mechanism were discussed. - Highlights: • Ni and Co microparticles were synthesized by a wet chemical reduction method. • EM properties of absorber were remarkably influenced by Ni/Co molar ratio. • EMA performances can be adjusted by artificially changing Co/Ni molar ratio. • Enhanced EMA performances result from multiple EM attenuation mechanisms.

Porous NiCo2S4-halloysite hybrid self-assembled from nanosheets for high-performance asymmetric supercapacitor applications

Science.gov (United States)

Chai, Hui; Dong, Hong; Wang, Yucheng; Xu, Jiayu; Jia, Dianzeng

2017-04-01

The porous nanostructures have drawn considerable attention because of their abundant pore volume and unique properties that provide outstanding performance in catalysis and energy storage applications. This study proposes the growth mechanism of porous NiCo2S4 composited with halloysite (HL) via a self-assembly method using halloysite as a template and component. Electrochemical tests showed that the NiCo2S4-HL exhibited an ultrahigh specific capacitance (Csp) (589C g-1 at 1A g-1) and good cycle stability (Csp retention of 86% after 1000 cycles). The desirable capacitive performance of the NiCo2S4-HL can be attributed to the large specific surface area and short diffusion path for electrons and ions in the hierarchical porous structure. The superior electrochemical performances with the energy density of 35.48 W h kg-1 at a power density of 199.9 W kg-1 were achieved in an assembled aqueous asymmetric supercapacitor (ASC) device using NiCo2S4-HL as a positive electrode and N-doped graphene (NG) as a negative electrode. Moreover, the NiCo2S4-HL//NG asymmetric supercapacitor achieved outstanding cycle stability (also retained 83.2% after 1700 cycles). The high-performance of the ASC device will undoubtedly make the porous NiCo2S4-HL as potential electrode materials attractive in energy storage systems.

The peroxidase and oxidase-like activity of NiCo{sub 2}O{sub 4} mesoporous spheres: Mechanistic understanding and colorimetric biosensing

Energy Technology Data Exchange (ETDEWEB)

Su, Li, E-mail: suli@htu.edu.cn [Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, Xinxiang, Henan 453007 (China); Henan Key Laboratory of Green Chemical Media and Reactions, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Dong, Wenpei; Wu, Chengke; Gong, Yijun; Zhang, Yan; Li, Ling; Mao, Guojiang; Feng, Suling [Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, Xinxiang, Henan 453007 (China); Henan Key Laboratory of Green Chemical Media and Reactions, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007 (China)

2017-01-25

The synthesized NiCo{sub 2}O{sub 4} mesoporous spheres (MS) displayed intrinsic peroxidase and oxidase-like activity were firstly reported. The catalytic mechanism of the oxidase-like activity of NiCo{sub 2}O{sub 4} MS was analyzed in detail using the electron spin resonance (ESR) method. It is found that NiCo{sub 2}O{sub 4} MS could directly oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) but did not produce {sup 1}O{sub 2} and ·OH. And the mechanism of the peroxidase-like activity of NiCo{sub 2}O{sub 4} MS was also verified that the oxidation of TMB stemmed from not only ·OH but also {sup 1}O{sub 2}. Based on the NiCo{sub 2}O{sub 4} MS showed excellent peroxidase-like activity over a broad temperature range, especially at normal body temperature, a detection tool was designed for glucose determination in diabetics' serum samples. And this detection method based on NiCo{sub 2}O{sub 4} MS gave a lower limit of detection than the method using Co{sub 3}O{sub 4} NPs and NiO NPs, as the single-component oxides of NiCo{sub 2}O{sub 4}. Our study may open up the possibility to make a great influence on the next generation of enzyme mimetics system. - Highlights: • NiCo{sub 2}O{sub 4} MS were found to possess the peroxidase and oxidase-like activity. • The peroxidase-like activity of NiCo{sub 2}O{sub 4} MS was stemmed from not only ·OH but also {sup 1}O{sub 2}. • The oxidase-like activity may stem from NiCo{sub 2}O{sub 4} MS′ oxidation rather than ·OH and {sup 1}O{sub 2}. • A colorimetric detection tool is designed for glucose determination in serum samples.

Synthesis and characterization of NiCo_2O_4 nanoplates as efficient electrode materials for electrochemical supercapacitors

International Nuclear Information System (INIS)

Kim, Taehyun; Ramadoss, Ananthakumar; Saravanakumar, Balasubramaniam; Veerasubramani, Ganesh Kumar; Kim, Sang Jae

2016-01-01

Highlights: • NiCo_2O_4 nanoplates were synthesized through a facile approach. • The NiCo_2O_4 nanoplates electrode material exhibit a specific capacitance of 332 F g"−"1 at 5 mV s"−"1. • The fabricated NiCo_2O_4 electrode reveals 86% retention of initial capacitance after 2000 cycles. - Abstract: In the present work, NiCo_2O_4 nanoplates were prepared by a facile, low temperature, hydrothermal method, followed by thermal annealing and used supercapacitor applications. The physico-chemical characterization of as-prepared materials were investigated by means of X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR) and field emission scanning electron microscopy (FE-SEM). The electrochemical measurements demonstrate that the NiCo_2O_4 nanoplates electrode (NC-5) exhibits a high specific capacitance of 332 F g"−"1 at a scan rate of 5 mV s"−"1 and also retained about 86% of the initial specific capacitance value even after 2000 cycles at a current density of 2.5 A g"−"1. These results suggest that the fabricated electrode material has huge potential as a novel electrode material for electrochemical capacitors.

Ternary mixed metal Fe-doped NiCo2O4 nanowires as efficient electrocatalysts for oxygen evolution reaction

Science.gov (United States)

Yan, Kai-Li; Shang, Xiao; Li, Zhen; Dong, Bin; Li, Xiao; Gao, Wen-Kun; Chi, Jing-Qi; Chai, Yong-Ming; Liu, Chen-Guang

2017-09-01

Designing mixed metal oxides with unique nanostructures as efficient electrocatalysts for water electrolysis has been an attractive approach for the storage of renewable energies. The ternary mixed metal spinel oxides FexNi1-xCo2O4 (x = 0, 0.1, 0.25, 0.5, 0.75, 0.9, 1) have been synthesized by a facile hydrothermal approach and calcination treatment using nickel foam as substrate. Fe/Ni ratios have been proved to affect the nanostructures of FexNi1-xCo2O, which imply different intrinsic activity for oxygen evolution reaction (OER). SEM images show that Fe0.5Ni0.5Co2O4 has the uniform nanowires morphology with about 30 nm of the diameter and 200-300 nm of the length. The OER measurements show that Fe0.5Ni0.5Co2O4 exhibits the better electrocatalytic performances with lower overpotential of 350 mV at J = 10 mA cm-2. In addition, the smaller Tafel slope of 27 mV dec-1 than other samples with different Fe/Ni ratios for Fe0.5Ni0.5Co2O4 is obtained. The improved OER activity of Fe0.5Ni0.5Co2O4 may be attributed to the synergistic effects from ternary mixed metals especially Fe-doping and the uniform nanowires supported on NF. Therefore, synthesizing Fe-doped multi-metal oxides with novel nanostructures may be a promising strategy for excellent OER electrocatalysts and it also provides a facile way for the fabrication of high-activity ternary mixed metal oxides electrocatalysts.

Preparation and characterization of self-assembled layer by layer NiCo2O4–reduced graphene oxide nanocomposite with improved electrocatalytic properties

International Nuclear Information System (INIS)

Srivastava, Manish; Elias Uddin, Md.; Singh, Jay; Kim, Nam Hoon; Lee, Joong Hee

2014-01-01

Graphical abstract: NiCo 2 O 4 were grown on RGO by in situ synthesis process. FE-SEM investigation revealed self assembled layer by layer growth of NiCo 2 O 4 –RGO nanocomposite. NiCo 2 O 4 –RGO nanocomposite exhibited synergetic effect of NiCo 2 O 4 nanoparticles and RGO on its electrochemical performance. -- Highlights: • NiCo 2 O 4 were grown on RGO by in-situ synthesis process. • FE-SEM image revealed self-assembled layer by layer growth of NiCo 2 O 4 -RGO nanocomposite. • NiCo 2 O 4 -RGO nanocomposite exhibited synergetic effects on its electrochemical performance. -- Abstract: NiCo 2 O 4 nanoparticles dispersed on reduced graphene oxide (RGO) are prepared by simultaneously reducing graphene oxide (GO), nickel and cobalt nitrate via a hydrothermal method assisted by post annealing at low temperature. The method involves formation of hydroxides on GO using ammonia under hydrothermal conditions. Subsequent thermal treatment at 300 °C led to the conversion of hydroxides into single-phase NiCo 2 O 4 atop the RGO. The synthesized products are characterized through several techniques including X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The FE-SEM investigations reveal the growth of a layer by layer assembly of NiCo 2 O 4 –RGO (2:1) nanocomposite, where the NiCo 2 O 4 nanoparticles are tightly packed between the layers of RGO. Further, the catalytic properties of the NiCo 2 O 4 –RGO nanocomposite are investigated for the oxygen evolution reaction (OER) through cyclic voltammetry (CV) measurements. It is observed that the special structural features of the NiCo 2 O 4 –RGO (2:1) nanocomposite, including layer by layer assembly, integrity and excellent dispersion of the NiCo 2 O 4 nanoparticles atop the RGO, produced

Fabrication and characterization of single segment CoNiP and multisegment CoNiP/Au nanowires

International Nuclear Information System (INIS)

Luu Van Thiem; Le Tuan Tu

2014-01-01

This paper presents the fabrication of CoNiP single segment and CoNiP/Au multisegment nanowires. We have fabricated these nanowires by electrodeposition method into polycarbonate templates with a nominal pore diameter about 100 nm. The hysteresis loops were measured with the applied magnetic field parallel and perpendicular to the wire axis using a vibrating sample magnetometer (VSM). The structure morphology was observed by Scanning Electron Microscopy (SEM) and the element composition of CoNiP/Au multisegment nanowires were analyzed by EDS. The results show that nanowires are very uniform with the diameter of 100 nm. The observed coercivity (H C ) and squareness (Mr/Ms) of CoNiP single segment nanowires are larger than the CoNiP/Au multisegment nanowires. (author)

Magnetic exchange at realistic CoO/Ni interfaces

KAUST Repository

Grytsiuk, Sergii

2012-07-30

We study the CoO/Ni interface by first principles calculations. Because the lattice mismatch is large, a realistic description requires a huge supercell. We investigate two interface configurations: in interface 1 the coupling between the Ni and Co atoms is mediated by O, whereas in interface 2 the Ni and Co atoms are in direct contact. We find that the magnetization (including the orbital moment) in interface 1 has a similar value as in bulk Ni but opposite sign, while in interface 2 it grows by 164%. The obtained magnetic moments can be explained by the local atomic environments. In addition, we find effects of charge transfer between the interface atoms. The Co 3d local density of states of interface 2 exhibits surprisingly small deviations from the corresponding bulk result, although the first coordination sphere is no longer octahedral. © Springer-Verlag 2012.

Magnetic exchange at realistic CoO/Ni interfaces

KAUST Repository

Grytsyuk, Sergiy; Cossu, Fabrizio; Schwingenschlö gl, Udo

2012-01-01

We study the CoO/Ni interface by first principles calculations. Because the lattice mismatch is large, a realistic description requires a huge supercell. We investigate two interface configurations: in interface 1 the coupling between the Ni and Co atoms is mediated by O, whereas in interface 2 the Ni and Co atoms are in direct contact. We find that the magnetization (including the orbital moment) in interface 1 has a similar value as in bulk Ni but opposite sign, while in interface 2 it grows by 164%. The obtained magnetic moments can be explained by the local atomic environments. In addition, we find effects of charge transfer between the interface atoms. The Co 3d local density of states of interface 2 exhibits surprisingly small deviations from the corresponding bulk result, although the first coordination sphere is no longer octahedral. © Springer-Verlag 2012.

A Study of CO2 Methanation over Ni-Based Catalysts Supported by CNTs with Various Textural Characteristics

Directory of Open Access Journals (Sweden)

Yanyan Feng

2015-01-01

Full Text Available This work studied the influence of textural characteristics of CNTs on catalytic performance of Ni/CNTs for CO2 methanation. The CNTs supports were prepared by chemical vapor deposition method using Ni/MgO catalysts, and acetonitrile and ethanol were used as carbon sources, respectively. The Ni/CNTs catalysts were prepared via impregnation method and characterized by X-ray diffraction (XRD, N2 adsorption/desorption, and temperature-programmed reduction (H2-TPR techniques. The results indicated that the textural characteristics of CNTs supports significantly impacted on the catalytic performance of Ni/CNTs. The catalyst Ni/CNTs-E (CNTs using ethanol as carbon source had good reducibility, high specific surface area, and moderate defects, resulting in higher CO2 conversion and CH4 yield, followed by Ni/CNTs-C (commercial CNTs and Ni/CNTs-A (CNTs using acetonitrile as carbon source. Based on Arrhenius formula, activation energies of the catalysts were calculated and were found decreased for Ni/CNTs-A and Ni/CNTs-E.

Synthesis and crystal structures of nitratocobaltates Na2[Co(NO3)4], K2[Co(NO3)4], and Ag[Co(NO3)3] and potassium nitratonickelate K2[Ni(NO3)4

International Nuclear Information System (INIS)

Morozov, I. V.; Fedorova, A. A.; Albov, D. V.; Kuznetsova, N. R.; Romanov, I. A.; Rybakov, V. B.; Troyanov, S. I.

2008-01-01

The cobalt(II) and nickel(II) nitrate complexes with an island structure (Na 2 [Co(NO 3 ) 4 ] (I) and K 2 [Co(NO 3 ) 4 ] (II)] and a chain structure [Ag[Co(NO 3 ) 3 ] (III) and K 2 [Ni(NO 3 ) 4 ] (IV)] are synthesized and investigated using X-ray diffraction. In the anionic complex [Co(NO 3 ) 4 ] 2− of the crystal structure of compound I, the Co coordination polyhedron is a twisted tetragonal prism formed by the O atoms of four asymmetric bidentate nitrate groups. In the anion [Co(NO 3 ) 4 ] 2− of the crystal structure of compound II, one of the four NO 3 groups is monodentate and the other NO 3 groups are bidentate (the coordination number of the cobalt atom is equal to seven, and the cobalt coordination polyhedron is a monocapped trigonal prism). The crystal structures of compounds III and IV contain infinite chains of the compositions [Co(NO 3 ) 2 (NO 3 ) 2/2 ] − and [Ni(NO 3 ) 3 (NO 3 ) 2/2 ] 2− , respectively. In the crystal structure of compound III, seven oxygen atoms of one monodentate and three bidentate nitrate groups form a dodecahedron with an unoccupied vertex of the A type around the Co atom. In the crystal structure of compound IV, the octahedral polyhedron of the Ni atom is formed by five nitrate groups, one of which is terminal bidentate. The data on the structure of Co(II) coordination polyhedra in the known nitratocobaltates are generalized.

Synthesis and crystal structures of nitratocobaltates Na2[Co(NO3)4], K2[Co(NO3)4], and Ag[Co(NO3)3] and potassium nitratonickelate K2[Ni(NO3)4

International Nuclear Information System (INIS)

Morozov, I. V.; Fedorova, A. A.; Albov, D. V.; Kuznetsova, N. R.; Romanov, I. A.; Rybakov, V. B.; Troyanov, S. I.

2008-01-01

The cobalt(II) and nickel(II) nitrate complexes with an island structure (Na 2 [Co(NO 3 ) 4 ] (I) and K 2 [Co(NO 3 ) 4 ] (II)] and a chain structure [Ag[Co(NO 3 ) 3 ] (III) and K 2 [Ni(NO 3 ) 4 ] (IV)] are synthesized and investigated using X-ray diffraction. In the anionic complex [Co(NO 3 ) 4 ] 2- of the crystal structure of compound I, the Co coordination polyhedron is a twisted tetragonal prism formed by the O atoms of four asymmetric bidentate nitrate groups. In the anion [Co(NO 3 ) 4 ] 2- of the crystal structure of compound II, one of the four NO 3 groups is monodentate and the other NO 3 groups are bidentate (the coordination number of the cobalt atom is equal to seven, and the cobalt coordination polyhedron is a monocapped trigonal prism). The crystal structures of compounds III and IV contain infinite chains of the compositions [Co(NO 3 ) 2 (NO 3 ) 2/2 ] - and [Ni(NO 3 ) 3 (NO 3 ) 2/2 ] 2- , respectively. In the crystal structure of compound III, seven oxygen atoms of one monodentate and three bidentate nitrate groups form a dodecahedron with an unoccupied vertex of the A type around the Co atom. In the crystal structure of compound IV, the octahedral polyhedron of the Ni atom is formed by five nitrate groups, one of which is terminal bidentate. The data on the structure of Co(II) coordination polyhedra in the known nitratocobaltates are generalized

Spinel FeCo2S4 nanoflower arrays grown on Ni foam as novel binder-free electrodes for long-cycle-life supercapacitors

Science.gov (United States)

Deng, Cuifen; Yang, Lishan; Yang, Chunming; Shen, Ping; Zhao, Liping; Wang, Zhiyu; Wang, Chunhui; Li, Junhua; Qian, Dong

2018-01-01

Spinel FeCo2S4 nanoflower arrays grown on Ni foam (FeCo2S4@Ni) have been successfully fabricated via a facile hydrothermal sulfurization of the corresponding FeCo2O4 precursor. The results of X-ray diffraction and X-ray photoelectron spectroscopy characterizations affirm that partial Co2+/Co3+ ions in Co3S4 have been substituted by Fe2+/Fe3+ ions to form FeCo2S4. The obtained FeCo2S4@Ni exhibits an ultrahigh specific capacitance (1644.07 mF cm-2 at 50 mA cm-2) and a supreme cycling stability (∼100% after 10,000 cycles at 50 mA cm-2) as binder-free electrodes for supercapacitors. The cycling stability of the fabricated product is the highest among the documented ternary metallic sulfides so far. The excellent supercapacitive performance of FeCo2S4@Ni emanates from the unique architectures of Fe2Co2S4 nanoflower arrays constituted by ultrathin nanoflakes, three-dimensional porous and conductive Ni foam, and solid skeleton of Ni foam for robust connections to the Fe2Co2S4.

Solvent Extraction of Co, Ni and Mn from NCM Sulfate Leaching Solution of Li(NCMO2 Secondary Battery Scraps

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Hong Hyun Seon

2017-06-01

Full Text Available As a part of the study on recycling Li(NCMO2 lithium-ion battery scraps, solvent extraction experiments were performed using different extraction agents such as PC88A, Cyanex272 and D2EHPA to separate Co, Ni and Mn from the leaching solution. When the ratio of Mn to Ni was about 0.4 in the leaching solution, the separation factor for Co and Mn was found to be less than 10 so that the separation of Co and Ni was insufficient. When solvent extraction was done using the solution with the lower Mn/Ni ratio of 0.05 where Mn was removed by potassium permanganate and chlorine dioxide, more than 99% of Mn could be extracted through five courses of extraction using 30vol% D2EHPA while the extraction rates of Co and Ni were around 17% and 11%, respectively. In the case that Mn was removed from the solution, the extraction rate of Co was higher than 99% whereas less than 7% Ni was extracted using Cyanex272 suggesting that Co and Ni elements were effectively separated.

Construct hierarchical electrode with NixCo3-xS4 nanosheet coated on NiCo2O4 nanowire arrays grown on carbon fiber paper for high-performance asymmetric supercapacitors

Science.gov (United States)

Cao, Liujun; Tang, Gang; Mei, Jun; Liu, Hao

2017-08-01

In order to boost the energy density of supercapacitors, the strategy of using advanced pseudo-capacitive electrode and asymmetric device architecture is feasible and effective. Herein, we report a significant advance in the design and synthesis of a new hierarchically nanostructures with a series of controllable Ni/Co molar ratios of NixCo3-xS4 (i.e., NiCo2S4 and Ni2CoS4) nanosheets coatings have in situ grown on NiCo2O4 nanowires arrays on a flexible carbon fiber paper (CFP). Remarkably, the hybrid Ni2CoS4@NiCo2O4 composite electrode delivers the highest discharge gravimetric capacitance of 1501 F g-1, and areal capacitance of 1.86 F cm-2 at 1 mA cm-2. Furthermore, coupled with nitrogen-doped carbon xerogels anode, we have fabricated a 1.6 V asymmetric supercapacitor (Ni2CoS4@NiCo2O4//nitrogen-doped carbon xerogels), such device delivers a maximum energy and power densities of 32.2 Wh kg-1 and 2.5 kW kg-1 in 1.0 M KOH electrolyte, respectively, and an excellent cycling stability (∼87.6% retention after 10,000 cycles).

Mechanisms responsible for two possible electrochemical reactions in Li1.2Ni0.13Mn0.54Co0.13O2 used for lithium ion batteries

Science.gov (United States)

Konishi, Hiroaki; Hirano, Tatsumi; Takamatsu, Daiko; Gunji, Akira; Feng, Xiaoliang; Furutsuki, Sho; Okumura, Takefumi; Terada, Shohei; Tamura, Kazuhisa

2018-02-01

Two electrochemical reactions are possible in regard to Li1.2Ni0.13Mn0.54Co0.13O2 (0.5Li2MnO3-0.5LiNi0.33Mn0.33Co0.33O2), viz, Li2MnO3-like and LiNi0.33Mn0.33Co0.33O2-like reactions. The open circuit potential (OCP) and changes in crystal structure during the charge-discharge process of Li1.2Ni0.13Mn0.54Co0.13O2 were investigated to clarify the mechanism responsible for the two reactions. Li2MnO3 and LiNi0.33Mn0.33Co0.33O2 were separately prepared for the investigation, and the OCPs and crystal structures in these cathodes were measured and then compared with those for Li1.2Ni0.13Mn0.54Co0.13O2. The results obtained using X-ray diffraction (XRD) indicated that two phases existed in Li1.2Ni0.13Mn0.54Co0.13O2. The changes in crystal structure of the two phases during the charge-discharge process were similar to those in Li2MnO3 and LiNi0.33Mn0.33Co0.33O2. This indicated that two phases, viz, Li2MnO3-like and LiNi0.33Mn0.33Co0.33O2-like, existed in Li1.2Ni0.13Mn0.54Co0.13O2. Li2MnO3-like, LiNi0.33Mn0.33Co0.33O2-like, and Li2MnO3-like phases were found to contribute mainly to electrochemical reactions in the low, middle, and high state of charge (SOC) ranges during the charge process from the results obtained using XRD and electrochemical measurements carried out on Li1.2Ni0.13Mn0.54Co0.13O2. In contrast, the Li2MnO3-like and LiNi0.33Mn0.33Co0.33O2-like phases mainly contributed to electrochemical reactions in the low and high SOC ranges during the discharge process. Furthermore, the high polarization and potential decay during the charge-discharge cycling of Li1.2Ni0.13Mn0.54Co0.13O2 were mainly attributed to the Li2MnO3-like phase.

Synthesis and characterization of mesoporous spinel NiCo2O4 using surfactant-assembled dispersion for asymmetric supercapacitors

Science.gov (United States)

Hsu, Chun-Tsung; Hu, Chi-Chang

2013-11-01

A simple and scalable process has been developed for synthesizing spinel NiCo2O4 nanocrystals through a thermal decomposition method. The introduction of hexadecyltrimethylammonium bromide (CTAB, (C16H33)N(CH3)3Br) into precursor solutions significantly enhances the homogeneity and porosity of spinel NiCo2O4. The porosity and high specific surface area of NiCo2O4 preserves the brilliant pseudo-capacitive performances due to providing smooth paths for electrolyte penetration and ion diffusion into inner active sites. Morphologies and microstructures of the active materials are examined by transmission electron microscopic (TEM) and X-ray diffraction (XRD) analyses. Thermogravimetric analysis (TGA) is used to evaluate the thermal properties of precursor solutions. The electrochemical performances of NiCo2O4 are systematically characterized by cyclic voltammetry and charge-discharge tests. Asymmetric supercapacitors are assembled with these brilliant binary oxides as the positive electrode and activated carbon as the negative electrode. The highly porous NiCo2O4 exhibits superior capacitive performances, i.e., high specific capacitance (764 F g-1 at 2 mV s-1) and long cycle life.

Influence of the preparation method on the morphology of templated NiCo{sub 2}O{sub 4} spinel

Energy Technology Data Exchange (ETDEWEB)

Cabo, Moises; Pellicer, Eva, E-mail: eva.pellicer.icn@uab.cat; Rossinyol, Emma; Solsona, Pau [Universitat Autonoma de Barcelona, Departament de Fisica, Facultat de Ciencies (Spain); Castell, Onofre [Universitat Autonoma de Barcelona, Servei de Microscopia, Facultat de Ciencies (Spain); Surinach, Santiago; Baro, Maria Dolors [Universitat Autonoma de Barcelona, Departament de Fisica, Facultat de Ciencies (Spain)

2011-09-15

The synthesis of NiCo{sub 2}O{sub 4} spinel by several nanocasting strategies (i.e., multi-step nanocasting, one-step nanocasting and soft-templating), in which nickel and cobalt nitrates are used as precursors and Pluronic P123 as surfactant, is explored. First, in the multi-step nanocasting, the effect of the impregnation method (evaporation, solid-liquid and two-solvent) of the SBA-15 silica template on the morphology of NiCo{sub 2}O{sub 4} replica is investigated. The evaporation method seems to be the best choice to obtain mesoporous NiCo{sub 2}O{sub 4} powder which, after calcination at 375 Degree-Sign C and subsequent template removal, displays the highest surface area (93.1 m{sup 2}/g). We have also checked the feasibility of the one-step nanoscating approach for the synthesis of ordered NiCo{sub 2}O{sub 4} arrays, though this methodology entails severe difficulties, mainly related to the different decomposition temperature of the nitrate precursors and the P123 surfactant. Finally, randomly oriented, aggregated NiCo{sub 2}O{sub 4} nanoparticles are obtained by means of P123 surfactant-assisted soft-templating approach.

Carbon Supported Engineering NiCo2O4 Hybrid Nanofibers with Enhanced Electrocatalytic Activity for Oxygen Reduction Reaction

Directory of Open Access Journals (Sweden)

Diab Hassan

2016-09-01

Full Text Available The design of cheap and efficient oxygen reduction reaction (ORR electrocatalysts is of a significant importance in sustainable and renewable energy technologies. Therefore, ORR catalysts with superb electrocatalytic activity and durability are becoming a necessity but still remain challenging. Herein, we report C/NiCo2O4 nanocomposite fibers fabricated by a straightforward electrospinning technique followed by a simple sintering process as a promising ORR electrocatalyst in alkaline condition. The mixed-valence oxide can offer numerous accessible active sites. In addition, the as-obtained C/NiCo2O4 hybrid reveals significantly remarkable electrocatalytic performance with a highly positive onset potential of 0.65 V, which is only 50 mV lower than that of commercially available Pt/C catalysts. The analyses indicate that C/NiCo2O4 catalyst can catalyze O2-molecules via direct four electron pathway in a similar behavior as commercial Pt/C catalysts dose. Compared to single NiCo2O4 and carbon free NiCo2O4, the C/NiCo2O4 hybrid displays higher ORR current and more positive half-wave potential. The incorporated carbon matrices are beneficial for fast electron transfer and can significantly impose an outstanding contribution to the electrocatalytic activity. Results indicate that the synthetic strategy hold a potential as efficient route to fabricate highly active nanostructures for practical use in energy technologies.

Urchin-like NiCo2O4 nanoneedles grown on mesocarbon microbeads with synergistic electrochemical properties as electrodes for symmetric supercapacitors.

Science.gov (United States)

Zhang, Yu; Zhang, Yihe; Zhang, Deyang; Sun, Li

2017-07-25

Here, we report a facile method to fabricate NiCo 2 O 4 nanoneedles on mesocarbon microbeads (MCMB) and form a unique urchin-like core-shell structure. In this composite, the MCMB not only provided high conductivity to benefit effective electron transfer, but also offered abundant adsorption points to load the NiCo 2 O 4 nanoneedles. The aggregation of the NiCo 2 O 4 nanoneedles was therefore alleviated and each NiCo 2 O 4 grain was unfolded to gain easy access to the electrolyte for efficient ion transfer. When the NiCo 2 O 4 @MCMB composite was evaluated as an electrode material for supercapacitors, a synergistic effect was exerted with high specific capacitance (458 F g -1 at 1 A g -1 ) and large reversibility (116% capacitance retention after 3000 cycles), both of which were of great advantage over individual MCMB and NiCo 2 O 4 nanoneedles. The NiCo 2 O 4 @MCMB was also used to construct a symmetric supercapacitor, which showed enlarged voltage profiles and could light the LED device for a few minutes, further confirming its excellent electrochemical performance.

Porous NiCo_2S_4-halloysite hybrid self-assembled from nanosheets for high-performance asymmetric supercapacitor applications

International Nuclear Information System (INIS)

Chai, Hui; Dong, Hong; Wang, Yucheng; Xu, Jiayu; Jia, Dianzeng

2017-01-01

Highlights: • The NiCo_2S_4-HL nanomaterial is achieved via two-step hydrothermal approach. • The unique structures are assembled self-assembly by nanosheets. • The obtained electrode exhibits high capacitance and excellent retention. • An asymmetric supercapacitor also displays high energy density and outstanding cycling stability. • The high-performance of the device is possibly due to the introduction of HL and formation of composed nanosheets. - Abstract: The porous nanostructures have drawn considerable attention because of their abundant pore volume and unique properties that provide outstanding performance in catalysis and energy storage applications. This study proposes the growth mechanism of porous NiCo_2S_4 composited with halloysite (HL) via a self-assembly method using halloysite as a template and component. Electrochemical tests showed that the NiCo_2S_4-HL exhibited an ultrahigh specific capacitance (Csp) (589C g"−"1 at 1A g"−"1) and good cycle stability (Csp retention of 86% after 1000 cycles). The desirable capacitive performance of the NiCo_2S_4-HL can be attributed to the large specific surface area and short diffusion path for electrons and ions in the hierarchical porous structure. The superior electrochemical performances with the energy density of 35.48 W h kg"−"1 at a power density of 199.9 W kg"−"1 were achieved in an assembled aqueous asymmetric supercapacitor (ASC) device using NiCo_2S_4-HL as a positive electrode and N-doped graphene (NG) as a negative electrode. Moreover, the NiCo_2S_4-HL//NG asymmetric supercapacitor achieved outstanding cycle stability (also retained 83.2% after 1700 cycles). The high-performance of the ASC device will undoubtedly make the porous NiCo_2S_4-HL as potential electrode materials attractive in energy storage systems.

CO2/H2O adsorption equilibrium and rates on metal-organic frameworks: HKUST-1 and Ni/DOBDC.

Science.gov (United States)

Liu, Jian; Wang, Yu; Benin, Annabelle I; Jakubczak, Paulina; Willis, Richard R; LeVan, M Douglas

2010-09-07

Metal-organic frameworks (MOFs) have recently attracted intense research interest because of their permanent porous structures, huge surface areas, and potential applications as novel adsorbents and catalysts. In order to provide a basis for consideration of MOFs for removal of carbon dioxide from gases containing water vapor, such as flue gas, we have studied adsorption equilibrium of CO(2), H(2)O vapor, and their mixtures and also rates of CO(2) adsorption in two MOFs: HKUST-1 (CuBTC) and Ni/DOBDC (CPO-27-Ni or Ni/MOF-74). The MOFs were synthesized via solvothermal methods, and the as-synthesized products were solvent exchanged and regenerated before experiments. Pure component adsorption equilibria and CO(2)/H(2)O binary adsorption equilibria were studied using a volumetric system. The effects of H(2)O adsorption on CO(2) adsorption for both MOF samples were determined, and the results for 5A and NaX zeolites were included for comparison. The hydrothermal stabilities for the two MOFs over the course of repetitive measurements of H(2)O and CO(2)/H(2)O mixture equilibria were also studied. CO(2) adsorption rates from helium for the MOF samples were investigated by using a unique concentration-swing frequency response (CSFR) system. Mass transfer into the MOFs is rapid with the controlling resistance found to be macropore diffusion, and rate parameters were established for the mechanism.

NiCo2S4 nanorod embedded rGO sheets as electrodes for supercapacitor

Science.gov (United States)

Sarkar, Aatreyee; Bera, Supriya; Chakraborty, Amit Kumar

2018-04-01

We report the synthesis of a hybrid nanostructure based on NiCo2S4 and reduced graphene oxide (rGO) following a facile hydrothermal method. X-ray diffraction (XRD), and electron microscopy (FESEM and HRTEM) analyses showed rod-like NiCo2S4 nanostructures embedded in rGO sheets. The electrochemical analysis of the synthesized nanohybrid using cyclic voltammetry (CV) and galvanostatic charge discharge (GCD) revealed specific capacitance of 410 F/gm indicating its suitability as a good electrode material for supercapacitor.

Preparation of LiMO2(M=Co,Ni) cathode materials for intermediate temperature fuel cells by sol-gel processes

DEFF Research Database (Denmark)

Tao, S.W.; Wu, Q.Y.; Zhan, Z.L.

1999-01-01

LiMO2 (M = Co, Ni) was prepared by complexing sol-gel processes. The phase and thermal stability were characterized by XRD and TG analyses. LiCoO2 and LiNiO2 phases are formed around 400 degrees C and 700 degrees C respectively in our synthesis process. LiNiO2 exhibit higher electrical conductivity...

Honeycomb-like NiCo2S4 nanosheets prepared by rapid electrodeposition as a counter electrode for dye-sensitized solar cells

Science.gov (United States)

Yin, Jie; Wang, Yuqiao; Meng, Wenfei; Zhou, Tianyue; Li, Baosong; Wei, Tao; Sun, Yueming

2017-08-01

Honeycomb-like nickel cobalt sulfide (NiCo2S4) nanosheets were directly deposited on fluorine-doped tin oxide substrate by a rapid voltammetric deposition method. The method was also controllable and feasible for preparing NiCo2S4 on flexible Ti foil without any heating processes. Compared with Pt, CoS and NiS, NiCo2S4 exhibited low charge-transfer resistances and excellent electrocatalytic activity for {{{{I}}}3}- reduction, acting as a counter electrode for a dye-sensitized solar cell. The NiCo2S4-based solar cell showed higher power conversion efficiency (7.44%) than that of Pt-based solar cell (7.09%) under simulated illumination (AM 1.5 G, 100 mW cm-2). The device based on the flexible NiCo2S4/Ti foil achieved a power conversion efficiency of 5.28% under the above illumination conditions. This work can be extended to flexible and wearable technologies due to its facile technique.

Structural and compositional optimization of the LiNi{sub 0.8}Co{sub 0.2}O{sub 2} electrode by new synthesis conditions

Energy Technology Data Exchange (ETDEWEB)

Mosqueda L, Y.; Milian P, C. R.; Pomares A, M.; Rodriguez H, J.; Perez C, E., E-mail: yodalgis@imre.oc.uh.cu [Havana University, Institute of Materials Science and Technology, Zapata y G, Plaza de la Revolucion, Vedado, 10400 Havana (Cuba)

2012-07-01

The optimization of citrate precursor method to obtain the LiNi{sub 0.8}Co{sub 0.2}O{sub 2} oxide from the thermal decomposition of the citrate precursor (NH{sub 4}){sub 3}LiNi{sub 0.8}Co{sub 0.2}(C{sub 6}H{sub 5}O{sub 7}) is presented. The optimization procedure consists of both the lithium atmosphere and the reaction time control during the decomposition of the citrate precursor. Were obtained and characterized two kind of the (Li{sub l-x}Ni{sub x})(Ni{sub 0.8}Co{sub 0.2})O{sub 2} oxides, with and without optimized synthesis conditions, identified as A and B oxides, respectively. The A and B oxides are characterized by compositional, structural and electrochemical studies. The results showed that is possible to reach the ordered oxide phase at smaller reaction time if the lithium atmosphere is controlled. From the combination of the chemical analysis by Icp and the DRX Rietveld structural refinement it is possible to establish the Li, Ni(II), Ni(III) and Co(III) composition with great accuracy. The resulted structural and compositional transformations have a close relation with technological parameters of the rechargeable lithium battery using Li Ni{sub 0.8}Co{sub 0.2}O{sub 2} oxide as cathode. (Author)

Morphology-controllable synthesis of 3D CoNiO_2 nano-networks as a high-performance positive electrode material for supercapacitors

International Nuclear Information System (INIS)

Zhang, Jijun; Chen, Zexiang; Wang, Yan; Li, Hai

2016-01-01

Here, we report a novel three-dimensional (3D) assembly of CoNiO_2 nanowire networks using a facile and scalable hydrothermal method followed by an annealing process for supercapacitor applications. The X-ray diffraction (XRD) results revealed the formation of highly-crystalline CoNiO_2 nano-networks. Scanning electron microscope (SEM) analysis showed the formation of a 3D interconnected network of CoNiO_2 nanowires during the synthesis. In addition, a formation mechanism for 3D CoNiO_2 nano-networks was proposed. Electrochemical analysis showed a typical pseudocapacitive behavior for the CoNiO_2 nanowire networks. The as-prepared CoNiO_2 electrode exhibited a high specific capacitance of 1462 F g"−"1 (45.32 F cm"−"2) at a current density of 1 A g"−"1 (31 mA cm"−"2) and an excellent rate capability of 1000 F g"−"1 (31 F cm"−"2) at 32 A g"−"1 (992 mA cm"−"2). Moreover, a good cycle stability was achieved at 4 A g"−"1 with no degradation over 800 cycles, indicating the stable 3D structure of CoNiO_2 after the redox reactions. The high rate capability and the good cycle stability indicated that the as-prepared 3D CoNiO_2 electrode could satisfy the needs of supercapacitors with both high power and energy densities. - Highlights: • A three-dimensional (3D) assembly of CoNiO_2 nanowire networks was prepared. • Sodium-p-styrenesulfonate (PSS) plays a key role in forming the structure. • The as-prepared 3D CoNiO_2 electrode exhibits high power and energy densities. • The proposed method is easy to provide an industrial mass production. • The method can be used to fabricate different morphologies of nanomaterials.

Transport properties of the LiNi{sub 1-y}Co{sub y}O{sub 2} system

Energy Technology Data Exchange (ETDEWEB)

Molenda, J.; Wilk, P.; Marzec, J. [Department of Solid State Chemistry, Stanislaw Staszic University of Mining and Metallurgy, Al. A. Mickiewicza 30, 30-059 Cracow (Poland)

1999-04-15

In this paper results are presented concerning structure, electrical conductivity and thermoelectric power measurements of the LiNi{sub 1-y}Co{sub y}O{sub 2} system. It has been stated that holes are dominating carriers. It has been also found that cobalt worsens the transport properties of the LiNi{sub 1-y}Co{sub y}O{sub 2} system

Microwave absorption properties of NiCoFe2O4-graphite embedded poly(o-phenetidine nanocomposites

Directory of Open Access Journals (Sweden)

Anil Ohlan

2011-09-01

Full Text Available Poly(o-phenetidine nanocomposites (PNG with NiCoFe2O4 and exfoliated graphite have been synthesized via in-situ emulsion polymerization. Systematic investigations reveal that the NiCoFe2O4 nanoparticles (30-40 nm in the poly(o-phenetidine matrix have phenomenal effect in determining the electrical, magnetic, and the microwave absorption properties of the nanocomposites. Shielding effectiveness due to absorption (SEA value of 32 dB (>99.9% has been achieved for PNG composite for its use as broadband microwave absorbing material. The microwave absorption of these composites can be attributed to dielectric loss from graphite and poly(o-phenetidine matrix, and magnetic loss from NiCoFe2O4 nanoparticles.

Sea urchin-likeNiCoO2@C nanocompositesforLi-ionbatteries and supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Liang, Jin; Xi, Kai; Tan, Guoqiang; Chen, Sheng; Zhao, Teng; Coxon, Paul R.; Kim, Hyun-Kyung; Ding, Shujiang; Yang, Yuan; Kumar, R. Vasant; Lu, Jun

2016-09-01

The rational construction of battery electrode architecture that offers both high energy and power densities on a gravimetric and volumetric basis is a critical concern but achieving this aim is beset by many fundamental and practical challenges. Here we report a new sea urchin-like NiCoO2@C composite electrode architecture composed of NiCoO2 nanosheets grown on hollow concave carbon disks. Such a unique structural design not only preserves all the advantages of hollow structures but also increases the packing density of the active materials. NiCoO2 nanosheets grown on carbon disks promote a high utilization of active materials in redox reactions by reducing the path length for Li+ ions and for electron transfer. Meanwhile, the hollow concave carbon not only reduces the volume change, but also improves the volumetric energy density of the entire composite electrode. As a result, the nanocomposites exhibit superior electrochemical performance measured in terms of high capacity/capacitance, stable cycling performance and good rate capability in both Li-ion battery and supercapacitor applications. Such nanostructured composite electrode may also have great potential for application in other electrochemical devices.

Electrodeposited binder-free NiCo2O4@carbon nanofiber as a high performance anode for lithium ion batteries

Science.gov (United States)

Zhang, Jie; Chu, Ruixia; Chen, Yanli; Jiang, Heng; Zhang, Ying; Huang, Nay Ming; Guo, Hang

2018-03-01

Binder-free nickel cobaltite on a carbon nanofiber (NiCo2O4@CNF) anode for lithium ion batteries was prepared via a two-step procedure of electrospinning and electrodeposition. The CNF was obtained by annealing electrospun poly-acrylonitrile (PAN) in nitrogen (N2). The NiCo2O4 nanostructures were then grown on the CNF by electrodeposition, followed by annealing in air. Experimental results showed that vertically aligned NiCo2O4 nanosheets had uniformly grown on the surface of the CNF, forming an interconnected network. The NiCo2O4@CNF possessed considerable lithium storage capacity and cycling stability. It exhibited a high reversible capacity of 778 mAhg-1 after 300 cycles at a current density of 0.25 C (1 C = 890 mAg-1) with an average capacity loss rate of 0.05% per cycle. The NiCo2O4@CNF had considerable rate capacities, delivering a capacity of 350 mAhg-1 at a current density of 2.0 C. The outstanding electrochemical performance can be mainly attributed to the following: (1) The nanoscale structure of NiCo2O4 could not only shorten the diffusion path of lithium ions and electrons but also increase the specific surface area, providing more active sites for electrochemical reactions. (2) The CNF with considerable mechanical strength and electrical conductivity could function as an anchor for the NiCo2O4 nanostructure and ensure an efficient electron transfer. (3) The porous structure resulted in a high specific surface area and an effective buffer for the volume changes during the repeated charge-discharge processes. Compared with a conventional hydrothermal method, electrodeposition could significantly simplify the preparation of NiCo2O4, with a shorter preparation period and lower energy consumption. This work provides an alternative strategy to obtain a high performance anode for lithium ion batteries.

NiCo_2O_4@TiN Core-shell Electrodes through Conformal Atomic Layer Deposition for All-solid-state Supercapacitors

International Nuclear Information System (INIS)

Wang, Ruiqi; Xia, Chuan; Wei, Nini; Alshareef, Husam N.

2016-01-01

Highlights: • NiCo_2O_4 nanostructures are prepared via a simple hydrothermal method. • Outer shell of TiN is then grown through conformal atomic layer deposition. • Electrodes exhibit significantly enhanced rate capability with TiN coating. • Solid-state polymer electrolyte is employed to improve cycling stability. • Full devices show a stack power density of 58.205 mW cm"−"3 at 0.061 mWh cm"−"3. - Abstract: Ternary transition metal oxides such as NiCo_2O_4 show great potential as supercapacitor electrode materials. However, the unsatisfactory rate performance of NiCo_2O_4 may prove to be a major hurdle to its commercial usage. Herein, we report the development of NiCo_2O_4@TiN core–shell nanostructures for all-solid-state supercapacitors with significantly enhanced rate capability. We demonstrate that a thin layer of TiN conformally grown by atomic layer deposition (ALD) on NiCo_2O_4 nanofiber arrays plays a key role in improving their electrical conductivity, mechanical stability, and rate performance. Fabricated using the hybrid NiCo_2O_4@TiN electrodes, the symmetric all-solid-state supercapacitor exhibited an impressive stack power density of 58.205 mW cm"−"3 at a stack energy density of 0.061 mWh cm"−"3. To the best of our knowledge, these values are the highest of any NiCo_2O_4-based all-solid-state supercapacitor reported. Additionally, the resulting NiCo_2O_4@TiN all-solid-state device displayed outstanding cycling stability by retaining 70% of its original capacitance after 20,000 cycles at a high current density of 10 mA cm"−"2. These results illustrate the promise of ALD-assisted hybrid NiCo_2O_4@TiN electrodes within sustainable and integrated energy storage applications.

Novel topotactically transformed carbon-CoO-NiO-NiCo₂O₄ nanosheet hybrid hetero-structured arrays as ultrahigh performance supercapacitors.

Science.gov (United States)

Wang, Hai; Guo, Junling; Qing, Chen; Sun, Daming; Wang, Bixiao; Tang, Yiwen

2014-08-14

A novel carbon-CoO-NiO-NiCo2O4 integrated electrode has been designed by reducing the hetero-structured NiCo2O4 nanosheet array with C2H2 on the nickel foam at a low temperature of 350 °C. The topotactical transformation from NiCo2O4 to the integrated electrode has been first conceived and investigated. Such unique nanoarchitectures exhibit excellent electrochemical performance with ultrahigh capacitance and desirable cycle life at high rates.

Mesoporous NiCo2O4 nano-needles supported by 3D interconnected carbon network on Ni foam for electrochemical energy storage

Science.gov (United States)

Lu, Congxiang; Liu, Wen-wen; Pan, Hui; Tay, Beng Kang; Wang, Xingli; Liang, Kun; Wei, Xuezhe

2018-05-01

In this work, a three dimensional (3D) interconnected carbon network consisting of ultrathin graphite (UG) and carbon nanotubes (CNTs) on Ni foam is fabricated and employed as a novel type of substrate for mesoporous NiCo2O4 nano-needles. The successfully synthesized NiCo2O4 nano-needles/CNTs/UG on Ni foam has many advantages including facile electrolyte access and direct conducting pathways towards current collectors, which enable it to be a promising electrode material in battery-like electrochemical energy storage. Encouragingly, a high capacity of 135.1 mAh/g at the current density of 1 A/g, superior rate performance and also stable cycling for 1200 cycles at the current density of 5 A/g have been demonstrated in this novel material.

Sono-synthesis and characterization of bimetallic Ni-Co/Al2O3-MgO nanocatalyst: Effects of metal content on catalytic properties and activity for hydrogen production via CO2 reforming of CH4.

Science.gov (United States)

Abdollahifar, Mozaffar; Haghighi, Mohammad; Babaluo, Ali Akbar; Talkhoncheh, Saeed Khajeh

2016-07-01

Sono-dispersion of Ni, Co and Ni-Co over Al2O3-MgO with Al/Mg ratio of 1.5 was prepared and tested for dry reforming of methane. The samples were characterized by XRD, FESEM, PSD, EDX, TEM, BET and FTIR analyses. In order to assess the effect of ultrasound irradiation, Ni-Co/Al2O3-MgO with Co content of 8% prepared via sonochemistry and impregnation methods. The sono-synthesized sample showed better textural properties and higher activity than that of impregnated one. Comparison of XRD patterns indicated that the NiO peaks became broader by increasing Co content over the support. The FESEM images displayed the particles are small and well-dispersed as a result of sonochemistry method. Also, EDX analysis demonstrated better dispersion of Ni and Co as a result of sonochemistry method in confirmation of XRD analysis. The sono-synthesized Ni-Co/Al2O3-MgO as a superior nanocatalyst with Co content of 3% illustrates much higher conversions (97.5% and 99% for CH4 and CO2 at 850 °C), yields (94% and 96% for H2 and CO at 850 °C) and 0.97 of H2/CO molar ratio in all samples using an equimolar feed ratio at 850 °C. During the 1200 min stability test, H2/CO molar ratio remained constant for the superior nanocatalyst. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation of Au/Y2O3 and Au/NiO catalysts by co-precipitation and their oxidation activities

International Nuclear Information System (INIS)

Sreethawong, Thammanoon; Sitthiwechvijit, Norsit; Rattanachatchai, Apiwat; Ouraipryvan, Piya; Schwank, Johannes W.; Chavadej, Sumaeth

2011-01-01

Research highlights: → The catalytic activity of Au catalysts supported on Y 2 O 3 and NiO prepared by co-precipitation was investigated for CO and methanol oxidation. → The phase transformation of yttrium support greatly affected the CO oxidation activity. → The Au/Y 2 O 3 exhibited the same activity as Au/NiO for the methanol oxidation while the Au/NiO gave higher activity for CO oxidation. - Abstract: The objective of this work was to investigate the catalytic activity of gold catalysts supported on two metal oxides, yttrium oxide and nickel oxide, prepared by co-precipitation for CO and methanol oxidation reactions. The TGA and XRD results confirmed that yttrium hydroxide (Y(OH) 3 ) was formed at calcination temperature below 300 deg. C. When it was calcined at 400 deg. C, the Y(OH) 3 was transformed to yttrium oxide hydroxide (YOOH). Finally, when calcination temperature was raised to 600 deg. C, the YOOH was completely transformed to yttrium oxide (Y 2 O 3 ). Interestingly, the gold loaded on YOOH calcined at 400 deg. C and gold loaded on Y 2 O 3 calcined at 500 deg. C comparatively showed the highest catalytic activity for complete CO oxidation at a reaction temperature of 300 deg. C. The 0.12% Au/Y 2 O 3 catalyst calcined at 500 deg. C was employed for both CO and methanol oxidation studies. For complete CO oxidation, the reaction temperatures of Au/Y 2 O 3 and Au/NiO catalysts were 325 deg. C and 250 deg. C, respectively. The light-off temperatures of Au/Y 2 O 3 and Au/NiO catalysts for methanol oxidation were 210 deg. C and 205 deg. C, respectively. Conclusively, the Au/Y 2 O 3 clearly exhibited the same activity as that of Au/NiO for methanol oxidation while the Au/NiO gave higher activity for CO oxidation.

Local atomic characterization of LiCo1/3Ni1/3Mn1/3O2 cathode material

International Nuclear Information System (INIS)

Nedoseykina, Tatiana; Kim, Sung-Soo; Nitta, Yoshiaki

2006-01-01

Co, Ni and Mn K-edge XAFS investigation of LiCo 1/3 Ni 1/3 Mn 1/3 O 2 as alternative cathode material to commercially used LiCoO 2 in lithium rechargeable battery has been performed. Parameters of a local atomic structure such as radii of metal-oxygen and metal-metal coordination shells and disorder in those shells have been determined. It has been found that the radius of the first coordination shell (metal-oxygen) as well as a local disorder in the second shell (metal-metal) around each of the 3d-metals are in a good agreement with obtained for superlattice model of √3 x √3] R30 o type in triangular lattice of sites by first principle calculation. Other parameters of the local atomic structure around Co, Ni and Mn atoms do not provide evidence for presence of superstructure in LiCo 1/3 Ni 1/3 Mn 1/3 O 2

Evaluation of Ca3(Co,M2O6 (M=Co, Fe, Mn, Ni as new cathode materials for solid-oxide fuel cells

Directory of Open Access Journals (Sweden)

Fushao Li

2015-10-01

Full Text Available Series compounds Ca3(Co0.9M0.12O6 (M=Co, Fe, Mn, Ni with hexagonal crystal structure were prepared by sol–gel route as the cathode materials for solid oxide fuel cells (SOFCs. Effects of the varied atomic compositions on the structure, electrical conductivity, thermal expansion and electrochemical performance were systematically evaluated. Experimental results showed that the lattice parameters of Ca3(Co0.9Fe0.12O6 and Ca3(Co0.9Mn0.12O6 were both expanded to certain degree. Electron-doping and hole-doping effects were expected in Ca3(Co0.9Mn0.12O6 and Ca3(Co0.9Ni0.12O6 respectively according to the chemical states of constituent elements and thermal-activated behavior of electrical conductivity. Thermal expansion coefficients (TEC of Ca3(Co0.9M0.12O6 were measured to be distributed around 16×10−6 K−1, and compositional elements of Fe, Mn, and Ni were especially beneficial for alleviation of the thermal expansion problem of cathode materials. By using Ca3(Co0.9M0.12O6 as the cathodes operated at 800 °C, the interfacial area-specific resistance varied in the order of M=CoCo. Among all of these compounds, Ca3(Co0.9Fe0.12O6 showed the best electrochemical performance and the power density as high as ca. 500 mW cm−2 at 800 °C achieved in the single cell with La0.8Sr0.2Ga0.83Mg0.17O2.815 as electrolyte and Ni–Ce0.8Sm0.2O1.9 as anode. Ca3(Co0.9M0.12O6 (M=Co, Fe, Mn, Ni can be used as the cost-effective cathode materials for SOFCs.

Vastly Enhanced BiVO4 Photocatalytic OER Performance by NiCoO2 as Cocatalyst

KAUST Repository

Palaniselvam, Thangavelu

2017-08-07

Here, a simple and efficient preparation of NiCoO nanoparticle modified nanoporous bismuth vanadate (BiVO) thin film and its application in photoelectrocatalytic (PEC) oxygen evolution reaction (OER) is demonstrated. The role of NiCoO in the composite electrode (BiVO/NiCoO) is twofold: OER cocatalyst and band structure modifier. It improves surface reaction kinetics for PEC OER and enhances charge separation efficiency simultaneously, which is believed to be a determining factor for the unprecedentedly high PEC OER performance of this BiVO/NiCoO nanocomposite. The photocurrent density of 3.6 mA cm at 1.23 V versus RHE in 0.1 m potassium phosphate buffered (pH = 7) electrolyte by BiVO/NiCoO is three times that of BiVO and significantly higher than most literature values. The BiVO/NiCoO nanocomposite shows/possess a high charge separation efficiency (η) of ≈72% as compared to only 23% for pure nanoporous BiVO at 1.23 V versus RHE, which demonstrates convincing role of NiCoO in the composite electrode. Both the excellent photocurrent density and great operational stability of this BiVO/NiCoO nanocomposite makes it a promising photocatalytic material for practical applications.

Electrochemical properties of LaNi{sub 4.2}Co{sub 0.4}Zn{sub 0.1}Al{sub 0.3} and LaNi{sub 4.3}Co{sub 0.4}Zn{sub 0.1}Al{sub 0.2} alloys as anode materials for Ni-MH batteries

Energy Technology Data Exchange (ETDEWEB)

Giza, Krystyna [Czestochowa Univ. of Technology (Poland). Faculty of Production Engineering and Materials Technology

2017-07-01

The galvanostatic charge and discharge technique was used for the evaluation of the changes in electrochemical parameters of the tested metal hydride electrodes during the repeated hydrogen absorption and desorption processes. Higher development of the effective surface area during hydrogenation has been obtained for LaNi{sub 4.3}Co{sub 0.4}Zn{sub 0.1}Al{sub 0.2} composite electrode. For the conditions of current ± 0.5 C, the discharge capacities of LaNi{sub 4.2}Co{sub 0.4}Zn{sub 0.1}Al{sub 0.3} and LaNi{sub 4.3}Co{sub 0.4}Zn{sub 0.1}Al{sub 0.2} alloys are 240 and 316 mAh x g{sup -1}, respectively. From the point of view of improving the kinetics of the process of charge transfer at the electrode/electrolyte interface as well as a resistance to self-discharging, a partial substitution of nickel with zinc in the LaNi{sub 4.3}Co{sub 0.4}Al{sub 0.3} alloy is not favorable.

Experimental investigation of phase equilibria in the Co-Ni-Zr ternary system

Energy Technology Data Exchange (ETDEWEB)

Liu, Xingjun; Yang, Shuiyuan; Yu, Wenjie; Wang, Cuiping [Xiamen Univ. (China). Fujian Key Laboratory of Materials Genome; Xiong, Huaping; Cheng, Yaoyong; Wu, Xin [Beijing Institute of Aeronautical Materials (China). Div. of Welding and Forging

2016-10-15

The phase equilibria of the Co-Ni-Zr ternary system at 1 000 C, 1 100 C and 1 200 C were experimentally investigated by means of back-scattered electron imaging, electron probe microanalysis and X-ray diffraction on the equilibrated ternary alloys. In this study, no ternary compound is found. The (αCo, Ni) phase region extends from the Ni-rich corner to the Co-rich corner with small solubility of Zr at three sections. At 1 000 C and 1 100 C, Ni{sub 5}Zr, Co{sub 2}Zr and Ni{sub 10}Zr{sub 7} phases have large solid solution ranges, but Ni{sub 10}Zr{sub 7} phase disappears at 1 200 C. The Ni{sub 7}Zr{sub 2}, NiZr, Co{sub 11}Zr{sub 2}, Co{sub 23}Zr{sub 6} and CoZr phases exhibit nearly linear compounds in the studied sections, and have large composition ranges. Additionally, some differences in phase relationship exist among the above three isothermal sections.

Study of highly efficient power generation system based on chemical-looping combustion; Chemical loop nenshoho ni yoru kokoritsu hatsuden system no kaihatsu ni kansuru kenkyu

Energy Technology Data Exchange (ETDEWEB)

Ishida, S; Suzuki, T; Yamamoto, M [Tokyo Institute of Technology, Tokyo (Japan). Research Laboratory of Resources Utilization

1997-02-01

This paper describes the research and development of power generation system by means of chemical-looping combustion. For this system, fuel flows in a reduction reactor and air flows in an oxidation reactor. These two flows are separated. As a result, recovery of CO2 without energy consumption, drastic improvement of power generation efficiency, and suppression of NOx emission are expected. To realize the above, two promising candidates, NiCoO2/YSZ and NiO2/NiAl2O4, have been found as recycle solid particles between the both reactors. These have excellent oxidation/reduction cycle characteristics. By these particles as well as the existing particle, NiO/YSZ, practical application of the chemical-looping combustion is realized. Besides LNG, coal and hydrogen were considered as fuels. When using coal or hydrogen, it was found that temperature of the reduction reactor should be increased the same as that of the oxidation reactor. This is a different point from a case using LNG as a fuel. 5 refs., 2 figs.

Hierarchical (Ni,Co)Se 2 /Carbon Hollow Rhombic Dodecahedra Derived from Metal-Organic Frameworks for Efficient Water-Splitting Electrocatalysis

KAUST Repository

Ming, Fangwang

2017-08-12

In this work, we demonstrate that the electrocatalytic activity of transition metal chalcogenides can be greatly enhanced by simultaneously engineering the active sites, surface area, and conductivity. Using metal-organic frameworks-derived (Ni,Co)Se2/C hollow rhombic dodecahedra (HRD) as a demonstration, we show that the incorporation of Ni into CoSe2 could generates additional active sites, the hierarchical hollow structure promotes the electrolyte diffusion, the in-situ hybridization with C improves the conductivity. As a result, the (Ni,Co)Se2/C HRD exhibit superior performance toward the overall water-splitting electrocatalysis in 1M KOH with a cell voltage as low as 1.58V at the current density of 10mAcm−2, making the (Ni,Co)Se2/C HRD as a promising alternative to noble metal catalysts for water splitting.

Hierarchical (Ni,Co)Se 2 /Carbon Hollow Rhombic Dodecahedra Derived from Metal-Organic Frameworks for Efficient Water-Splitting Electrocatalysis

KAUST Repository

Ming, Fangwang; Liang, Hanfeng; Shi, Huanhuan; Mei, Gui; Xu, Xun; Wang, Zhoucheng

2017-01-01

In this work, we demonstrate that the electrocatalytic activity of transition metal chalcogenides can be greatly enhanced by simultaneously engineering the active sites, surface area, and conductivity. Using metal-organic frameworks-derived (Ni,Co)Se2/C hollow rhombic dodecahedra (HRD) as a demonstration, we show that the incorporation of Ni into CoSe2 could generates additional active sites, the hierarchical hollow structure promotes the electrolyte diffusion, the in-situ hybridization with C improves the conductivity. As a result, the (Ni,Co)Se2/C HRD exhibit superior performance toward the overall water-splitting electrocatalysis in 1M KOH with a cell voltage as low as 1.58V at the current density of 10mAcm−2, making the (Ni,Co)Se2/C HRD as a promising alternative to noble metal catalysts for water splitting.

Crystal-field splitting in coadsorbate systems: c (2x2) CO/K/Ni (100)

NARCIS (Netherlands)

Hasselström, J.; Föhlisch, A.; Denecke, R.; Nilsson, A.; Groot, F.M.F. de

2000-01-01

It is demonstrated how the crystal field splitting (CFS) fine structure can be used to characterize a coadsor-bate system. We have applied K 2p x-ray absorption spectroscopy (XAS) to the c(2x2) CO/K/Ni(100) system. The CFS fine structure is shown to be sensitive to the the local atomic

Hydrogen sorption and corrosion properties of La{sub 2}Ni{sub 9}CoSn{sub 0.2} alloy

Energy Technology Data Exchange (ETDEWEB)

Giza, Krystyna; Adamczyk, Lidia [Czestochowa Univ. of Technology (Poland). Faculty of Production Engineering and Materials Technology; Drulis, Henryk; Hackemer, Alicja [Institute of Low Temperatures and Structure Research PAS, Wroclaw (Poland)

2018-02-15

The hydrogenation and corrosion behaviour of La{sub 2}Ni{sub 9} . CoSn{sub 0.2} alloy was analysed in respect of its use in Ni-MH batteries. It has been proved that the presence of tin in the alloy causes a decrease in hydrogen equilibrium pressure. In the electrochemical studies several techniques, such as chronopotentiometry, multi-potential steps, linear sweep voltammetry and the potentiokinetic polarization were applied to characterize the electrochemical properties of a La{sub 2}Ni{sub 9}CoSn{sub 0.2} powder composite electrode. During long cycling, powder particles undergo micro-cracking or other forms of surface development causing a progressive increase in the exchange current density of the H{sub 2}O/H{sub 2} system, but, on the other hand, this increase favours corrosion processes such as the electrode material's oxidation. This is also reflected in the capacity loss values.

Soft magnetic properties of hybrid ferromagnetic films with CoFe, NiFe, and NiFeCuMo layers

Energy Technology Data Exchange (ETDEWEB)

Choi, Jong-Gu [Eastern-western Biomedical Engineering, Sangji University, Wonju 220-702 (Korea, Republic of); Hwang, Do-Guwn [Dept. of Oriental Biomedical Engineering, Sangji University, Wonju 220-702 (Korea, Republic of); Rhee, Jang-Roh [Dept. of Physics, Sookmyung Women' s University, Seoul 140-742 (Korea, Republic of); Lee, Sang-Suk, E-mail: sslee@sangji.ac.kr [Dept. of Oriental Biomedical Engineering, Sangji University, Wonju 220-702 (Korea, Republic of)

2011-09-30

Two-layered ferromagnetic alloy films (NiFe and CoFe) with intermediate NiFeCuMo soft magnetic layers of different thicknesses were investigated to understand the relationship between coercivity and magnetization process by taking into account the strength of hard-axis saturation field. The thickness dependence of H{sub EC} (easy-axis coercivity), H{sub HS} (hard-axis saturation field), and {chi} (susceptibility) of the NiFeCuMo thin films in glass/Ta(5 nm)/[CoFe or NiFe(5 nm-t/2)]/NiFeCuMo(t = 0, 4, 6, 8, 10 nm)/[CoFe or NiFe(5 nm-t/2)]/Ta(5 nm) films prepared using the ion beam deposition method was determined. The magnetic properties (H{sub EC}, H{sub HS}, and {chi}) of the ferromagnetic CoFe, NiFe three-layers with an intermediate NiFeCuMo super-soft magnetic layer were strongly dependent on the thickness of the NiFeCuMo layer.

Prussian Blue Analogues Derived Penroseite (Ni,Co)Se2 Nanocages Anchored on 3D Graphene Aerogel for Efficient Water Splitting

KAUST Repository

Xu, Xun; Liang, Hanfeng; Ming, Fangwang; Qi, Zhengbing; Xie, Yaqiang; Wang, Zhoucheng

2017-01-01

Efficient water splitting demands highly active, low cost, and robust electrocatalysts. In this study, we report the synthesis of penroseite (Ni,Co)Se2 nanocages anchored on 3D graphene aerogel using Prussian blue analogues as precursor and further their applications in overall water splitting electrolysis. The synergy between the high activity of (Ni,Co)Se2 and the good conductivity of graphene leads to superior performance of the hybrid toward the water splitting in basic solutions. The (Ni,Co)Se2-GA only requires a low cell voltage of 1.60 V to reach the current density of 10 mA cm-2, making the (Ni,Co)Se2-GA hybrid a competitive alternative to noble metal based catalysts for water splitting.

Prussian Blue Analogues Derived Penroseite (Ni,Co)Se2 Nanocages Anchored on 3D Graphene Aerogel for Efficient Water Splitting

KAUST Repository

Xu, Xun

2017-08-14

Efficient water splitting demands highly active, low cost, and robust electrocatalysts. In this study, we report the synthesis of penroseite (Ni,Co)Se2 nanocages anchored on 3D graphene aerogel using Prussian blue analogues as precursor and further their applications in overall water splitting electrolysis. The synergy between the high activity of (Ni,Co)Se2 and the good conductivity of graphene leads to superior performance of the hybrid toward the water splitting in basic solutions. The (Ni,Co)Se2-GA only requires a low cell voltage of 1.60 V to reach the current density of 10 mA cm-2, making the (Ni,Co)Se2-GA hybrid a competitive alternative to noble metal based catalysts for water splitting.

Densities of molten Ni-(Cr, Co, W) superalloys

Institute of Scientific and Technical Information of China (English)

XIAO Feng; YANG Ren-hui; FANG Liang; LIU Lan-xiao; ZHAO Hong-kai

2008-01-01

In order to obtain more accurate density for molten Ni-(Cr, Co, W) binary alloy, the densities of molten pure Ni and Ni-Cr, Ni-Co, Ni-W alloys were measured with a sessile drop method. It is found that the measured densities of molten pure Ni and Ni-Cr, Ni-Co, Ni-W alloys decrease with increasing temperature in the experimental temperature range. The density of alloys increases with increasing W and Co concentrations while it decreases with increasing Cr concentration in the alloy at 1 773-1 873 K. The molar volume of Ni-based alloys increases with increasing W concentration while it decreases with increasing Co concentration. The effect of Cr concentration on the molar volume of the alloy is little in the studied concentration range. The accommodation among atomic species was analyzed. The deviation of molar volume from ideal mixing shows an ideal mixing of Ni-(Cr, Co, W) binary alloys.

Nickel Nanowire@Porous NiCo{sub 2}O{sub 4} Nanorods Arrays Grown on Nickel Foam as Efficient Pseudocapacitor Electrode

Energy Technology Data Exchange (ETDEWEB)

Wan, Houzhao; Li, Lang; Zhang, Jun; Liu, Xiang; Wang, Hanbin; Wang, Hao, E-mail: nanoguy@126.com [Faculty of Physics and Electronic Science, Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Hubei Key Laboratory of Ferro & Piezoelectric Materials and Devices, Hubei University, Wuhan (China)

2017-12-13

A three dimensional hierarchical nanostructure composed of nickel nanowires and porous NiCo{sub 2}O{sub 4} nanorods arrays on the surface of nickel foam is successfully fabricated by a facile route. In this structure, the nickel nanowires are used as core materials to support high-pseudocapacitance NiCo{sub 2}O{sub 4} nanorods and construct the well-defined NiCo{sub 2}O{sub 4} nanorods shell/nickel nanowires core hierarchical structure on nickel foam. Benefiting from the participation of nickel nanowires, the nickel nanowire@NiCo{sub 2}O{sub 4}/Ni foam electrode shows a high areal specific capacitance (7.4 F cm{sup −2} at 5 mA cm{sup −2}), excellent rate capability (88.04% retained at 100 mA cm{sup −2}), and good cycling stability (74.08% retained after 1,500 cycles). The superior electrochemical properties made it promising as electrode for supercapacitors.

Effect of Nb and F Co-doping on Li1.2Mn0.54Ni0.13Co0.13O2 Cathode Material for High-Performance Lithium-Ion Batteries

Directory of Open Access Journals (Sweden)

Lei Ming

2018-04-01

Full Text Available The Li1.2Mn0.54−xNbxCo0.13Ni0.13O2−6xF6x (x = 0, 0.01, 0.03, 0.05 is prepared by traditional solid-phase method, and the Nb and F ions are successfully doped into Mn and O sites of layered materials Li1.2Mn0.54Co0.13Ni0.13O2, respectively. The incorporating Nb ion in Mn site can effectively restrain the migration of transition metal ions during long-term cycling, and keep the stability of the crystal structure. The Li1.2Mn0.54−xNbxCo0.13Ni0.13O2−6xF6x shows suppressed voltage fade and higher capacity retention of 98.1% after 200 cycles at rate of 1 C. The replacement of O2− by the strongly electronegative F− is beneficial for suppressed the structure change of Li2MnO3 from the eliminating of oxygen in initial charge process. Therefore, the initial coulombic efficiency of doped Li1.2Mn0.54−xNbxCo0.13Ni0.13O2−6xF6x gets improved, which is higher than that of pure Li1.2Mn0.54Co0.13Ni0.13O2. In addition, the Nb and F co-doping can effectively enhance the transfer of lithium-ion and electrons, and thus improving rate performance.

Effect of H2O and Y(O on Oxidation Behavior of NiCoCrAl Coating Within Thermal Barrier Coating

Directory of Open Access Journals (Sweden)

WANG Yi-qun

2017-04-01

Full Text Available NiCoCrAl coatings containing Y and Y oxide were made using vacuum plasma deposition and high-velocity oxygen fuel respectively, high temperature oxidation dynamics and cross-section microstructures of NiCoCrAl+Y and NiCoCrAl+Y(O coatings in Ar-16.7%O2, Ar-3.3%H2O and Ar-0.2%H2-0.9%H2O at 1100℃ were investigated by differential thermal analysis (DTA and optical and electron microscope. The influencing mechanism of Y oxide on the oxidation of coatings at different atmosphere was compared by computation using First-Principles. The results show that Al2O3 layer on NiCoCrAl+Y coatings has more holes for internal oxidation on account of the element Y diffusion and enrichment on the interface. In addition, steam can promote the internal oxidation. While a thinner and uniform alumina form on NiCoCrAl+Y(O coatings because element Y is pinned by oxygen atoms during the preparation of coatings. Water vapor has less influence on protective alumina formation on the NiCoCrAl+Y(O coating. Therefore, oxidation behavior of NiCoCrAl coatings vary in composition and structure in different oxidizing atmosphere. Besides, Y and Y-enrichment oxides have key influences on the microstructure and the growth rate.

Effect of d electrons on defect properties in equiatomic NiCoCr and NiCoFeCr concentrated solid solution alloys

Science.gov (United States)

Zhao, Shijun; Egami, Takeshi; Stocks, G. Malcolm; Zhang, Yanwen

2018-01-01

The role of d electrons in determining distributions of formation and migration energies for point defects in equiatomic NiCoCr and NiCoFeCr concentrated solid solution alloys (CSAs) are studied regarding electron density deformation flexibility based on first-principles calculations. The disordered state is taken into account by constructing special quasirandom structures. The migration barriers are determined by directly optimizing the saddle point. It is found that the formation energies of interstitials in CSAs are lower than those in pure Ni, whereas the formation energies of vacancies are higher. In both NiCoCr and NiCoFeCr, Co-related dumbbell interstitials exhibit lower formation energies. Notably, the distributions of migration energies for Cr interstitials and vacancies exhibit a remarkable overlap region. A detailed analysis of electronic properties reveals that the electronic charge deformation flexibility regarding eg to t2g transition has a dominant effect on defect energetics for different elements in CSAs. Thus the electron deformation ability is suggested as a key factor in understanding the peculiar defect behavior in CSAs.

Hydrothermal growth of hierarchical Ni3S2 and Co3S4 on a reduced graphene oxide hydrogel@Ni foam: a high-energy-density aqueous asymmetric supercapacitor.

Science.gov (United States)

Ghosh, Debasis; Das, Chapal Kumar

2015-01-21

Ni foam@reduced graphene oxide (rGO) hydrogel-Ni3S2 and Ni foam@rGO hydrogel-Co3S4 composites have been successfully synthesized with the aid of a two-step hydrothermal protocol, where the rGO hydrogel is sandwiched between the metal sulfide and Ni foam substrate. Sonochemical deposition of exfoliated rGO on Ni foam with subsequent hydrothermal treatment results in the formation of a rGO-hydrogel-coated Ni foam. Then second-time hydrothermal treatment of the dried Ni@rGO substrate with corresponding metal nitrate and sodium sulfide results in individual uniform growth of porous Ni3S2 nanorods and a Co3S4 self-assembled nanosheet on a Ni@rGO substrate. Both Ni@rGO-Ni3S2 and Ni@rGO-Co3S4 have been electrochemically characterized in a 6 M KOH electrolyte, exhibiting high specific capacitance values of 987.8 and 1369 F/g, respectively, at 1.5 A/g accompanied by the respective outstanding cycle stability of 97.9% and 96.6% at 12 A/g over 3000 charge-discharge cycles. An advanced aqueous asymmetric (AAS) supercapacitor has been fabricated by exploiting the as-prepared Ni@rGO-Co3S4 as a positive electrode and Ni@rGO-Ni3S2 as a negative electrode. The as-fabricated AAS has shown promising energy densities of 55.16 and 24.84 Wh/kg at high power densities of 975 and 13000 W/kg, respectively, along with an excellent cycle stability of 96.2% specific capacitance retention over 3000 charge-discharge cycles at 12 A/g. The enhanced specific capacitance, stupendous cycle stability, elevated energy density, and a power density as an AAS of these electrode materials indicate that it could be a potential candidate in the field of supercapacitors.

Characterization of particulate sol-gel synthesis of LiNi0.8Co0.2O2 via maleic acid assistance with different solvents

International Nuclear Information System (INIS)

Zhong, Y.D.; Zhao, X.B.; Cao, G.S.; Tu, J.P.; Zhu, T.J.

2006-01-01

Particulate sol-gel LiNi 0.8 Co 0.2 O 2 has been synthesized by a maleic-acid-assisted process using de-ionized water or ethanol as the solvent. A comparison of the effect on these two different solvents was made on the basis of thermal studies, Fourier transform infrared spectroscopy, X-ray diffraction analysis, chemical diffusion coefficients measurement, and electrochemical cyclability tests. An esterification reaction occurred on the xerogel prepared with ethanol as solvent, reducing Ni and Co from their nitrate salts. LiNi 0.8 Co 0.2 O 2 grew at the expense of Li 2 CO 3 , NiO, and CoO during calcination. Better results of capacity and cyclability were obtained in a DI-water-solvent sample associated with a larger interslab thickness between O-Li-O and lower Ni occupancy on the Li site. The activation energy for the calcinations of DI-water-solvent sample is one-half of that of the ethanol-solvent one, which could be the reason for its better properties. Chemical diffusion coefficients of Li + ion are of the same order 10 -10 cm 2 /s, is not affected by the solvents used and/or the temperature raise to 55 deg. C

Soot and NOx simultaneous reduction by use of CO2 mixed fuel; Ekika CO2 yokai nenryo ni yoru diesel kikan no susu, NOx no doji teigen

Energy Technology Data Exchange (ETDEWEB)

Senda, J; Yokoyama, T; Ikeda, M; Fujimoto, H [Doshisha University, Kyoto (Japan); Ifuku, Y [Kubota Corp., Osaka (Japan)

1997-10-01

We propose the new fuel injection system by use of diesel fuel dissolved with CO2 to reduce both soot and NOx simultaneously. In this paper spray combustion characteristics of CO2 mixed fuel is reported. It is revealed that flame temperature and KL factor at the CO2 mixed fuel combustion are lower than at the only n-tridecane combustion due to separation or partly flashing of CO2component. And the result of exhaust gas measurement shows the capability that CO2 mixed fuel is able to reduce both soot and NOx simultaneously. 12 refs., 7 figs., 1 tab.

Molecular Nickel Phosphide Carbonyl Nanoclusters: Synthesis, Structure, and Electrochemistry of [Ni11P(CO)18]3- and [H6-nNi31P4(CO)39]n- (n = 4 and 5).

Science.gov (United States)

Capacci, Chiara; Ciabatti, Iacopo; Femoni, Cristina; Iapalucci, Maria Carmela; Funaioli, Tiziana; Zacchini, Stefano; Zanotti, Valerio

2018-02-05

The reaction of [NEt 4 ] 2 [Ni 6 (CO) 12 ] in thf with 0.5 equiv of PCl 3 affords the monophosphide [Ni 11 P(CO) 18 ] 3- that in turn further reacts with PCl 3 resulting in the tetra-phosphide carbonyl cluster [HNi 31 P 4 (CO) 39 ] 5- . Alternatively, the latter can be obtained from the reaction of [NEt 4 ] 2 [Ni 6 (CO) 12 ] in thf with 0.8-0.9 equiv of PCl 3 . The [HNi 31 P 4 (CO) 39 ] 5- penta-anion is reversibly protonated by strong acids leading to the [H 2 Ni 31 P 4 (CO) 39 ] 4- tetra-anion, whereas deprotonation affords the [Ni 31 P 4 (CO) 39 ] 6- hexa-anion. The latter is reduced with Na/naphthalene yielding the [Ni 31 P 4 (CO) 39 ] 7- hepta-anion. In order to shed light on the polyhydride nature and redox behavior of these clusters, electrochemical and spectroelectrochemical studies were carried out on [Ni 11 P(CO) 18 ] 3- , [HNi 31 P 4 (CO) 39 ] 5- , and [H 2 Ni 31 P 4 (CO) 39 ] 4- . The reversible formation of the stable [Ni 11 P(CO) 18 ] 4- tetra-anion is demonstrated through the spectroelectrochemical investigation of [Ni 11 P(CO) 18 ] 3- . The redox changes of [HNi 31 P 4 (CO) 39 ] 5- show features of chemical reversibility and the vibrational spectra in the ν CO region of the nine redox states of the cluster [HNi 31 P 4 (CO) 39 ] n- (n = 3-11) are reported. The spectroelectrochemical investigation of [H 2 Ni 31 P 4 (CO) 39 ] 4- revealed the presence of three chemically reversible reduction processes, and the IR spectra of [H 2 Ni 31 P 4 (CO) 39 ] n- (n = 4-7) have been recorded. The different spectroelectrochemical behavior of [HNi 31 P 4 (CO) 39 ] 5- and [H 2 Ni 31 P 4 (CO) 39 ] 4- support their formulations as polyhydrides. Unfortunately, all the attempts to directly confirm their poly hydrido nature by 1 H NMR spectroscopy failed, as previously found for related large metal carbonyl clusters. Thus, the presence and number of hydride ligands have been based on the observed protonation/deprotonation reactions and the spectroelectrochemical

Synthesis of LiNi0.8Co0.1Mn0.1O2 cathode material by chloride co-precipitation method

Institute of Scientific and Technical Information of China (English)

李灵均; 李新海; 王志兴; 伍凌; 郑俊超; 李金辉

2010-01-01

LiNi0.8Co0.1Mn0.1O2 was prepared by a chloride co-precipitation method and characterized by thermogravimetric analysis, X-ray diffractometry with Rietveld refinement,electron scanning microscopy and electrochemical measurements.Effects of lithium ion content and sintering temperature on physical and electrochemical performance of LiNi0.8Co0.1Mn0.1O2 were also investigated. The results show that the sample synthesized at 750℃with 105%lithium content has fine particle sizes around 200 nm and homogenous sizes distribution.The initial discharge capacity for the powder is 184 mA·h/g between 2.7 and 4.3 V at 0.1C and room temperature.

Preparation and characterization of self-assembled layer by layer NiCo{sub 2}O{sub 4}–reduced graphene oxide nanocomposite with improved electrocatalytic properties

Energy Technology Data Exchange (ETDEWEB)

Srivastava, Manish; Elias Uddin, Md. [Advanced Materials Research Institute for BIN Fusion Technology (BK Plus Global Program), Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Singh, Jay [Department of Applied Chemistry, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110042 (India); Kim, Nam Hoon [Advanced Materials Research Institute for BIN Fusion Technology (BK Plus Global Program), Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Lee, Joong Hee, E-mail: jhl@chonbuk.ac.kr [Advanced Materials Research Institute for BIN Fusion Technology (BK Plus Global Program), Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Advanced Wind Power System Research Center, Department of Polymer and Nano Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of)

2014-03-25

Graphical abstract: NiCo{sub 2}O{sub 4} were grown on RGO by in situ synthesis process. FE-SEM investigation revealed self assembled layer by layer growth of NiCo{sub 2}O{sub 4}–RGO nanocomposite. NiCo{sub 2}O{sub 4}–RGO nanocomposite exhibited synergetic effect of NiCo{sub 2}O{sub 4} nanoparticles and RGO on its electrochemical performance. -- Highlights: • NiCo{sub 2}O{sub 4} were grown on RGO by in-situ synthesis process. • FE-SEM image revealed self-assembled layer by layer growth of NiCo{sub 2}O{sub 4}-RGO nanocomposite. • NiCo{sub 2}O{sub 4}-RGO nanocomposite exhibited synergetic effects on its electrochemical performance. -- Abstract: NiCo{sub 2}O{sub 4} nanoparticles dispersed on reduced graphene oxide (RGO) are prepared by simultaneously reducing graphene oxide (GO), nickel and cobalt nitrate via a hydrothermal method assisted by post annealing at low temperature. The method involves formation of hydroxides on GO using ammonia under hydrothermal conditions. Subsequent thermal treatment at 300 °C led to the conversion of hydroxides into single-phase NiCo{sub 2}O{sub 4} atop the RGO. The synthesized products are characterized through several techniques including X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The FE-SEM investigations reveal the growth of a layer by layer assembly of NiCo{sub 2}O{sub 4}–RGO (2:1) nanocomposite, where the NiCo{sub 2}O{sub 4} nanoparticles are tightly packed between the layers of RGO. Further, the catalytic properties of the NiCo{sub 2}O{sub 4}–RGO nanocomposite are investigated for the oxygen evolution reaction (OER) through cyclic voltammetry (CV) measurements. It is observed that the special structural features of the NiCo{sub 2}O{sub 4}–RGO (2:1) nanocomposite, including

Antiferromagnetic coupling of TbPc2 molecules to ultrathin Ni and Co films

Directory of Open Access Journals (Sweden)

David Klar

2013-05-01

Full Text Available The magnetic and electronic properties of single-molecule magnets are studied by X-ray absorption spectroscopy and X-ray magnetic circular dichroism. We study the magnetic coupling of ultrathin Co and Ni films that are epitaxially grown onto a Cu(100 substrate, to an in situ deposited submonolayer of TbPc2 molecules. Because of the element specificity of the X-ray absorption spectroscopy we are able to individually determine the field dependence of the magnetization of the Tb ions and the Ni or Co film. On both substrates the TbPc2 molecules couple antiferromagnetically to the ferromagnetic films, which is possibly due to a superexchange interaction via the phthalocyanine ligand that contacts the magnetic surface.

Mace-like hierarchical MoS2/NiCo2S4 composites supported by carbon fiber paper: An efficient electrocatalyst for the hydrogen evolution reaction

Science.gov (United States)

Sun, Lan; Wang, Tao; Zhang, Long; Sun, Yunjin; Xu, Kewei; Dai, Zhengfei; Ma, Fei

2018-02-01

The rational design and preparation of earth-abundant, stable and efficient electrocatalysts for hydrogen production is currently the subject in extensive scientific and technological researches toward the future of a clean-energy society. Herein, a mace-like MoS2/NiCo2S4 hierarchical structure is designed and synthesized on carbon fiber paper via a facile hydrothermal method, and evaluated as electrocatalyst for hydrogen evolution reaction. In the MoS2/NiCo2S4/carbon fiber paper hierarchical structures, MoS2 nanosheets are dispersively distributed on the surface of NiCo2S4 nanowires, which provides an enlarged surface area, abundant interfaces and catalytic active sites. As for hydrogen evolution reaction, such MoS2/NiCo2S4/carbon fiber paper heterostructures give rise to a hydrogen evolution reaction catalytic current density of 10 mA cm-2 with a lower overpotential of 139 mV and a smaller Tafel slope of 37 mV·dec-1 than those of MoS2/carbon fiber paper and NiCo2S4/carbon fiber paper counterparts, exhibiting a prominent electrocatalytic performance. Moreover, the electrocatalytic properties change little after 5000 CV cycles and continual electrolysis for 12 h without obvious decay, respectively, demonstrating high durability and stability. The excellent hydrogen evolution reaction performances endow the hierarchical configuration MoS2/NiCo2S4/carbon fiber paper with promising alternative in HER and other related renewable energy fields.

Neutron diffraction studies of the Na-ion battery electrode materials NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3}

Energy Technology Data Exchange (ETDEWEB)

Yahia, H. Ben [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 5825 Doha (Qatar); Essehli, R., E-mail: ressehli@qf.org.qa [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 5825 Doha (Qatar); Avdeev, M. [Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights NSW 2234 (Australia); Park, J-B.; Sun, Y-K. [Department of Energy Engineering Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Al-Maadeed, M.A. [Center for Advanced Materials (CAM), Qatar University, 2713 Doha (Qatar); Belharouak, I., E-mail: ibelharouak@qf.org.qa [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 5825 Doha (Qatar)

2016-06-15

The new compounds NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} were synthesized by sol-gel method and their crystal structures were determined by using neutron powder diffraction data. These compounds were characterized by galvanometric cycling and cyclic voltammetry. NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} crystallize with a stuffed α-CrPO{sub 4}-type structure. The structure consists of a 3D-framework made of octahedra and tetrahedra that are sharing corners and/or edges generating channels along [100] and [010], in which the sodium atoms are located. Of significance, in the structures of NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} a statistical disorder Ni{sup 2+}/Cr{sup 3+} was observed on both the 8g and 4a atomic positions, whereas in NaCoCr{sub 2}(PO{sub 4}){sub 3} the statistical disorder Co{sup 2+}/Cr{sup 3+} was only observed on the 8g atomic position. When tested as negative electrode materials, NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} delivered specific capacities of 352, 385, and 368 mA h g{sup −1}, respectively, which attests to the electrochemical activity of sodium in these compounds. - Highlights: • NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} were synthesized by sol-gel method. • The crystal structures were determined by using neutron powder diffraction data. • The three compounds crystallize with a stuffed α-CrPO{sub 4}-type structure. • The three compounds were tested as anodes in sodium-ion batteries. • Relatively high specific capacities were obtained for these compounds.

Recent Scientific Progress on Developing Supported Ni Catalysts for Dry (CO2 Reforming of Methane

Directory of Open Access Journals (Sweden)

Hyun Ook Seo

2018-03-01

Full Text Available Two major green house gases (CO2 and CH4 can be converted into useful synthetic gas (H2 and CO during dry reforming of methane (DRM reaction, and a lot of scientific efforts has been made to develop efficient catalysts for dry reforming of methane (DRM. Noble metal-based catalysts can effectively assist DRM reaction, however they are not economically viable. Alternatively, non-noble based catalysts have been studied so far, and supported Ni catalysts have been considered as a promising candidate for DRM catalyst. Main drawback of Ni catalysts is its catalytic instability under operating conditions of DRM (>700 °C. Recently, it has been demonstrated that the appropriate choice of metal-oxide supports can address this issue since the chemical and physical of metal-oxide supports can prevent coke formation and stabilize the small Ni nanoparticles under harsh conditions of DRM operation. This mini-review covers the recent scientific findings on the development of supported Ni catalysts for DRM reaction, including the synthetic methods of supported Ni nanoparticles with high sintering resistance.

Self-assembly of a [Ni8] carbonate cube incorporating four μ4-carbonato linkers through fixation of atmospheric CO2 by ligated [Ni2] complexes.

Science.gov (United States)

Ghosh, Aloke Kumar; Pait, Moumita; Shatruk, Michael; Bertolasi, Valerio; Ray, Debashis

2014-02-07

The communication reports the synthesis, characterization, and magnetic behavior of a novel μ4-carbonato supported and imidazole capped ligated nickel cage [Ni8(μ-H2bpmp)4(μ4-CO3)4(ImH)8](NO3)4·2H2O (1) through self-assembly of ligand bound ferromagnetic Ni2 building blocks. Structural analysis indicates newer geometrical features for the coordination cage formation and dominant interdimer antiferromagnetic coupling resulting in a diamagnetic ground state.

One-pot synthesis of CoNiO2 single-crystalline nanoparticles as high-performance electrode materials of asymmetric supercapacitors

Science.gov (United States)

Du, Weimin; Gao, Yanping; Tian, Qingqing; Li, Dan; Zhang, Zhenhu; Guo, Jiaojiao; Qian, Xuefeng

2015-09-01

A facile one-pot solvothermal method has been developed to synthesize CoNiO2 single-crystalline nanoparticles. Crystal phase, morphology, crystal lattice, and composition of the obtained products were characterized by X-ray diffraction, scanning electron microscope, high-resolution transmission electron microscopy, and energy-dispersive X-ray analysis, respectively. Results revealed that the as-synthesized CoNiO2 nanoparticles belong to cubic structure with narrow size-distribution (8-10 nm). Subsequently, new asymmetric supercapacitors were successfully assembled with CoNiO2 nanoparticles as positive electrode and activated carbon as negative electrode. The electrochemical results show that asymmetric supercapacitors based on CoNiO2 nanoparticles possess excellent supercapacitor properties, i.e., a stable electrochemical window of 0-1.7 V, higher energy density of 24.0 Wh/kg at a power density of 415.4 W/kg, and excellent cycling stability (96.8 % capacitance retention after 5000 charge-discharge cycles). Meanwhile, both a light-emitting diode and a mini fan can be powered by two series connection asymmetric supercapacitors. These results imply that the present asymmetric supercapacitors based on CoNiO2 nanoparticles possess the promising potential application in the field of high-performance energy storage.

One-pot synthesis of CoNiO2 single-crystalline nanoparticles as high-performance electrode materials of asymmetric supercapacitors

International Nuclear Information System (INIS)

Du, Weimin; Gao, Yanping; Tian, Qingqing; Li, Dan; Zhang, Zhenhu; Guo, Jiaojiao; Qian, Xuefeng

2015-01-01

A facile one-pot solvothermal method has been developed to synthesize CoNiO 2 single-crystalline nanoparticles. Crystal phase, morphology, crystal lattice, and composition of the obtained products were characterized by X-ray diffraction, scanning electron microscope, high-resolution transmission electron microscopy, and energy-dispersive X-ray analysis, respectively. Results revealed that the as-synthesized CoNiO 2 nanoparticles belong to cubic structure with narrow size-distribution (8–10 nm). Subsequently, new asymmetric supercapacitors were successfully assembled with CoNiO 2 nanoparticles as positive electrode and activated carbon as negative electrode. The electrochemical results show that asymmetric supercapacitors based on CoNiO 2 nanoparticles possess excellent supercapacitor properties, i.e., a stable electrochemical window of 0–1.7 V, higher energy density of 24.0 Wh/kg at a power density of 415.4 W/kg, and excellent cycling stability (96.8 % capacitance retention after 5000 charge–discharge cycles). Meanwhile, both a light-emitting diode and a mini fan can be powered by two series connection asymmetric supercapacitors. These results imply that the present asymmetric supercapacitors based on CoNiO 2 nanoparticles possess the promising potential application in the field of high-performance energy storage.

Electrochemical CO2 Reduction by Ni-containing Iron Sulfides: How Is CO2 Electrochemically Reduced at Bisulfide-Bearing Deep-sea Hydrothermal Precipitates?

International Nuclear Information System (INIS)

Yamaguchi, Akira; Yamamoto, Masahiro; Takai, Ken; Ishii, Takumi; Hashimoto, Kazuhito; Nakamura, Ryuhei

2014-01-01

The discovery of deep-sea hydrothermal vents on the late 1970's has led to many hypotheses concerning chemical evolution in the prebiotic ocean and the early evolution of energy metabolism in ancient Earth. Such studies stand on the quest for the bioenergetic evolution to utilize reducing chemicals such as H 2 for CO 2 reduction and carbon assimilation. In addition to the direct reaction of H 2 and CO 2 , the electrical current passing across a bisulfide-bearing chimney structure has pointed to the possible electrocatalytic CO 2 reduction at the cold ocean-vent interface (R. Nakamura, et al. Angew. Chem. Int. Ed. 2010, 49, 7692 − 7694). To confirm the validity of this hypothesis, here, we examined the energetics of electrocatalytic CO 2 reduction by iron sulfide (FeS) deposits at slightly acidic pH. Although FeS deposits inefficiently reduced CO 2 , the efficiency of the reaction was substantially improved by the substitution of Fe with Ni to form FeNi 2 S 4 (violarite), of which surface was further modified with amine compounds. The potential-dependent activity of CO 2 reduction demonstrated that CO 2 reduction by H 2 in hydrothermal fluids was involved in a strong endergonic electron transfer reaction, suggesting that a naturally occurring proton-motive force (PMF) as high as 200 mV would be established across the hydrothermal vent chimney wall. However, in the chimney structures, H 2 generation competes with CO 2 reduction for electrical current, resulting in rapid consumption of the PMF. Therefore, to maintain the PMF and the electrosynthesis of organic compounds in hydrothermal vent mineral deposits, we propose a homeostatic pH regulation mechanism of FeS deposits, in which elemental hydrogen stored in the hydrothermal mineral deposits is used to balance the consumption of the electrochemical gradient by H 2 generation

Coating effect of LiFePO4 and Al2O3 on Li1.2Mn0.54Ni0.13Co0.13O2 cathode surface for lithium ion batteries

Science.gov (United States)

Seteni, Bonani; Rapulenyane, Nomasonto; Ngila, Jane Catherine; Mpelane, Siyasanga; Luo, Hongze

2017-06-01

Lithium-manganese-rich cathode material Li1.2Mn0.54Ni0.13Co0.13O2 is prepared by combustion method, and then coated with nano-sized LiFePO4 and nano-sized Al2O3 particles via a wet chemical process. The as-prepared Li1.2Mn0.54Ni0.13Co0.13O2, LiFePO4-coated Li1.2Mn0.54Ni0.13Co0.13O2 and Al2O3-coated Li1.2Mn0.54Ni0.13Co0.13O2 are characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The scanning electron microscopy shows the agglomeration of the materials and their nanoparticle size ∼100 nm. The transmission electron microscopy confirms that LiFePO4 forms a rough mat-like surface and Al2O3 remain as islandic particles on the surface of the Li1.2Mn0.54Ni0.13Co0.13O2 material. The Li1.2Mn0.54Ni0.13Co0.13O2 coated with LiFePO4 and Li1.2Mn0.54Ni0.13Co0.13O2 coated with Al2O3 exhibits improved electrochemical performance. The initial discharge capacity is enhanced to 267 mAhg-1 after the LiFePO4 coating and 285 mAhg-1 after the Al2O3 coating compared to the as-prepared Li1.2Mn0.54Ni0.13Co0.13O2 material that has an initial discharge capacity of 243 mAhg-1. Galvanostatic charge-discharge tests at C/10 display longer activation of Li2MnO3 phase and higher capacity retention of 88% after 20 cycles for Li1.2Mn0.54Ni0.13Co0.13O2-LiFePO4 compared to Li1.2Mn0.54Ni0.13Co0.13O2-Al2O3 of 80% after 20 cycles and LMNC of 80% after 20 cycles. Meanwhile Li1.2Mn0.54Ni0.13Co0.13O2-LiFePO4 also shows higher rate capability compared to Li1.2Mn0.54Ni0.13Co0.13O2-Al2O3.

One-step hydrothermal synthesis of sandwich-type NiCo2S4@reduced graphene oxide composite as active electrode material for supercapacitors

Science.gov (United States)

Wang, Fangping; Li, Guifang; Zhou, Qianqian; Zheng, Jinfeng; Yang, Caixia; Wang, Qizhao

2017-12-01

A facile one step hydrothermal process is developed for the synthesis of NiCo2S4@reduced graphene oxide (NiCo2S4@RGO) composite as electrode for electrochemical supercapacitors. This NiCo2S4@RGO electrode exhibits an ultrahigh specific capacitance of 2003 F g-1 at 1 A g-1 and 1726 F g-1 at 20 A g-1 (86.0% capacitance retention from 1 A g-1 to 20 A g-1), excellent cycling stabilities (86.0% retention after 3500 cycles). Moreover, an asymmetric supercapacitor is successfully assembled by using NiCo2S4@RGO nanoparticle as the positive electrode and active carbon(AC) as the negative electrode in 2 M KOH electrolyte. The fabricated NiCo2S4@RGO//AC asymmetric supercapacitor exhibits a high energy density of 21.9 Wh kg-1 at a power density of 417.1 W kg-1 and still remains an impressive energy density of 13.5 Wh kg-1 at a large power density of 2700 W kg-1. The results demonstrate that the NiCo2S4@RGO composite is a promising electrode material as supercapacitors in energy storage.

Fast synthesis of porous NiCo{sub 2}O{sub 4} hollow nanospheres for a high-sensitivity non-enzymatic glucose sensor

Energy Technology Data Exchange (ETDEWEB)

Huang, Wei; Cao, Yang; Chen, Yong [State Key Laboratory of Marine Resource Utilization in South China Sea, College of Materials and Chemical Engineering, Hainan University, Haikou 570228 (China); Peng, Juan; Lai, Xiaoyong [Laboratory Cultivation Base of Natural Gas Conversion, School of Chemistry and Chemical Engineering, Ningxia University, Yinchuan 750021 (China); Tu, Jinchun, E-mail: tujinchun@hainu.edu.cn [State Key Laboratory of Marine Resource Utilization in South China Sea, College of Materials and Chemical Engineering, Hainan University, Haikou 570228 (China)

2017-02-28

Highlights: • Porous NiCo{sub 2}O{sub 4} hollow nanospheres were synthesized via a facile “CEP” approach and the synthesis mechanism was discussed. • The NiCo{sub 2}O{sub 4} hollow nanospheres possess superior electron-transfer capability and electrocatalytic activity. • The sensitivity is as high as 1917 μA·mM{sup −1}·cm{sup −2} and the detection limit is as low as 0.6 μM (S/N = 3). - Abstract: In this paper, we report the fast synthesis of porous NiCo{sub 2}O{sub 4} hollow nanospheres via a polycrystalline Cu{sub 2}O-templated route based on the elaborately designed “coordinating etching and precipitating” process. The composition and morphology of the porous NiCo{sub 2}O{sub 4} hollow nanospheres were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The electron-transfer capability and electrocatalytic activity of the materials were investigated by electrochemical impedance spectroscopy and cyclic voltammetry. NiCo{sub 2}O{sub 4} was endowed with superior electron-transfer capability, large surface area, and abundant intrinsic redox couples of Ni{sup 2+}/Ni{sup 3+} and Co{sup 2+}/Co{sup 3+} ions; thus, the modified electrode exhibited excellent glucose-sensing properties, with a high sensitivity of 1917 μA·mM{sup −1}·cm{sup −2} at a low concentration, a good linear range from 0.01 mM to 0.30 mM and from 0.30 mM to 2.24 mM, and a low detection limit of 0.6 μM (S/N = 3).

Verifying the Rechargeability of Li-CO2 Batteries on Working Cathodes of Ni Nanoparticles Highly Dispersed on N-Doped Graphene.

Science.gov (United States)

Zhang, Zhang; Wang, Xin-Gai; Zhang, Xu; Xie, Zhaojun; Chen, Ya-Nan; Ma, Lipo; Peng, Zhangquan; Zhou, Zhen

2018-02-01

Li-CO 2 batteries could skillfully combine the reduction of "greenhouse effect" with energy storage systems. However, Li-CO 2 batteries still suffer from unsatisfactory electrochemical performances and their rechargeability is challenged. Here, it is reported that a composite of Ni nanoparticles highly dispersed on N-doped graphene (Ni-NG) with 3D porous structure, exhibits a superior discharge capacity of 17 625 mA h g -1 , as the air cathode for Li-CO 2 batteries. The batteries with these highly efficient cathodes could sustain 100 cycles at a cutoff capacity of 1000 mA h g -1 with low overpotentials at the current density of 100 mA g -1 . Particularly, the Ni-NG cathodes allow to observe the appearance/disappearance of agglomerated Li 2 CO 3 particles and carbon thin films directly upon discharge/charge processes. In addition, the recycle of CO 2 is detected through in situ differential electrochemical mass spectrometry. This is a critical step to verify the electrochemical rechargeability of Li-CO 2 batteries. Also, first-principles computations further prove that Ni nanoparticles are active sites for the reaction of Li and CO 2 , which could guide to design more advantageous catalysts for rechargeable Li-CO 2 batteries.

X-ray spectra, chemical bonding, and electron structure of ScM2Si2 (M = Fe, Co, Ni)

International Nuclear Information System (INIS)

Shcherba, I.D.; Kotur, B.Ya.

1990-01-01

In a study of the interaction of the components in the ternary systems Sc-M-Si (where M is a 3d transition metal) it was established that there are compounds of the empirical formula ScM 2 Si 2 (M = Fe, Co, Ni). They crystallize in two structural types, HfFe 2 Si 2 (the compound ScFe 2 Si 2 ) and CeGa 2 Al 2 (ScCo 2 Si 2 and ScNi 2 Si 2 ) (ref. 1), leading to different coordination environment of the atoms in the structures of the compounds. With the aim of investigating the electron structure and the type ofin these compounds, they authors made a systematic x-ray spectral investigation with simultaneous analysis of the crystal structures of ScM 2 Si 2

Reduction under hydrogen of ferrite MFe{sub 2}O{sub 4} (M: Fe, Co, Ni) nanoparticles obtained by hydrolysis in polyol medium: A novel route to elaborate CoFe{sub 2}, Fe and Ni{sub 3}Fe nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Ballot, N.; Schoenstein, F.; Mercone, S.; Chauveau, T.; Brinza, O. [Laboratoire des Sciences des Procedes et des Materiaux, CNRS, LSPM - UPR 3407, Universite Paris 13, PRES Sorbonne-Paris-Cite, 99 Avenue J.-B. Clement, 93430 Villetaneuse (France); Jouini, N., E-mail: jouini@univ-paris13.fr [Laboratoire des Sciences des Procedes et des Materiaux, CNRS, LSPM - UPR 3407, Universite Paris 13, PRES Sorbonne-Paris-Cite, 99 Avenue J.-B. Clement, 93430 Villetaneuse (France)

2012-09-25

Highlights: Black-Right-Pointing-Pointer Spinels nano-particles MFe{sub 2}O{sub 4} (M: Co, Fe or Ni) are obtained by hydrolysis in polyol medium. Black-Right-Pointing-Pointer Gentle reduction under hydrogen flow of spinel nano-particles yields metal and alloy nanoparticles. Black-Right-Pointing-Pointer TEM and X-ray analysis show that CoFe{sub 2}, Fe and Ni{sub 3}Fe nano-particles are monocrystalline particles with size less than 160 nm. Black-Right-Pointing-Pointer Iron with size of 150 nm presents ferromagnetic behavior. Black-Right-Pointing-Pointer CoFe{sub 2} alloy with size of 55 nm could be considered as a superparamagnetic material. - Abstract: A novel method to process metal and various alloy particles of nanometric size is described. The first step consists in the elaboration of MFe{sub 2}O{sub 4} (M: Fe, Ni or Co) spinel nanoparticles in polyol medium via hydrolysis and the second one in gently reducing these latter under hydrogen at 300 Degree-Sign C. X-ray diffraction analysis shows that pure Fe and CoFe{sub 2} alloy are well obtained by reducing Fe{sub 3}O{sub 4} and CoFe{sub 2}O{sub 4}, respectively. This is not the case when we try to reduce NiFe{sub 2}O{sub 4}. A mixture of Fe and Ni{sub 3}Fe is observed. TEM analysis reveals that the size of metal particles stays within the range of a few tenths of nm up to 150 nm, while the precursors (MFe{sub 2}O{sub 4}) never exceed 5 nm. Our results show that the formation of metal particles occurs via two main steps: (i) reduction of the spinel oxide nanoparticles into metal ones and (ii) aggregation of the latter, leading to larger metal nanoparticles. Magnetic measurements indicate that the as-obtained metallic materials have good magnetic properties mainly affected by the sizes of the nanoparticles and the purity of the reduced phases.

Ni-Co nanosheets supported on conductive “core” for integrated supercapacitor with high performance

International Nuclear Information System (INIS)

Gao, Ying; Wang, Lei; Zhang, Wenping; Yang, Xiuyun; Ma, Yuqin; Shao, Jing; Li, Yunhui

2016-01-01

Highlights: • Hierarchical Ni-Co is fabricated by growing nanosheet on dispersive nanorod surface. • Nanosheets are benefit for ion adsorption/de-adsorption and surface redox reactions. • Interlayer Ni serves as current collector and electronic conductor. • Self-support Ni-Co electrode manifests high specific capacitance and good stability. - Abstract: Developing supercapacitors with high energy density, fast charging rates, and superior cycle life is crucial to the ever-increasing electric energy storage. However, how to construct a new type of supercapacitors involving pseudocapacitive performance and electric double-layer capacitive performance and exhibiting enhanced electronic conductivity is still challenging. Here, hierarchical Ni_xCo_2_x(OH)_y@Ni@ZnO/ITO architecture is successfully fabricated by growing Ni_xCo_2_x(OH)_y nanosheets on surface of well-aligned Ni@ZnO nanorod using co-electrodeposition method. Ni_xCo_2_x(OH)_y with layered structure is wrapped like rippled silk and increases the specific surface area, which is crucial and benefit for fast ion adsorption/de-adsorption and fast surface redox reactions. Importantly, interlayer Ni serves as a nanostructured current collector and electronic conductor, playing an important role in rate capability. By virtue of structure features, the self-support Ni_xCo_2_x(OH)_y@Ni@ZnO/ITO as binder-free electrode for supercapacitors manifests higher specific capacitance (124 mF cm"−"2 at 0.1 mA cm"−"2, the mass of active material per square centimeter is typically in 100s micrograms). Furthermore, the Ni_xCo_2_x(OH)_y@Ni@ZnO/ITO exhibits remarkable cycling stability with about 95% specific capacitance retention after 5000 cycles. The results show that Ni-Co nanostructure constructed on surface of embedded conductive “core” materials is promising for high-energy supercapacitors.

Structure, morphology and thermal stability of electrochemically obtained Ni-Co deposits

Energy Technology Data Exchange (ETDEWEB)

Rafailovic, L.D. [Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria); Artner, W. [Centre of Electrochemical Surface Technology (CEST), Viktor-Kaplan-Strasse 2, A-2700 Wr. Neustadt (Austria); Nauer, G.E. [Centre of Electrochemical Surface Technology (CEST), Viktor-Kaplan-Strasse 2, A-2700 Wr. Neustadt (Austria); Faculty of Chemistry, University of Vienna, Waehringer Strasse 42, A-1090 Vienna (Austria); Minic, D.M., E-mail: dminic@ffh.bg.ac.rs [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12, 11000 Belgrade (Serbia)

2009-12-10

Nanostructured nickel-cobalt alloy powder deposits were obtained electrochemically on Cu substrates in the current density range 40-400 mA cm{sup -2}. The influence of the current density and of the Ni{sup 2+}/Co{sup 2+} ratio in the bath on the microstructure and phase composition of the Ni-Co deposits was studied by SEM and X-ray diffraction methods. Both the bath composition and the current density strongly influence the deposit growth mechanism as well as the deposit composition, microstructure, grain size and surface morphology. If the concentration ratio in the electrolyte is Ni{sup 2+}/Co{sup 2+} = 4, the deposit has a cauliflower structure with mean grain size of 13 nm. In contrast, the particles deposited from the electrolyte with Ni{sup 2+}/Co{sup 2+} = 0.25 show platelet structure with preferred orientations and mean grain size of 20 nm. When electrodeposition was performed at high overpotentials, far from equilibrium conditions, face-centered cubic (FCC) solid solutions of Ni and Co were generated while at low overpotentials, as well as at higher content of cobalt in the electrolyte, hexagonal-close packed (HCP) Co was formed. The structure of nanocrystalline deposits exhibits a strong tendency to structural changes under annealing. DSC of the alloy deposits shows a stepwise process of structural changes in the temperature range from 393 to 823 K. It was found that under annealing, HCP {yields} FCC phase transformation occurs in nanocrystalline deposit obtained from electrolyte with a concentration ratio Ni{sup 2+}/Co{sup 2+} = 0.25.

Effect of Ti content on structure and properties of Al2CrFeNiCoCuTix high-entropy alloy coatings

International Nuclear Information System (INIS)

Qiu, X.W.; Zhang, Y.P.; Liu, C.G.

2014-01-01

Highlights: • Al 2 CrFeNiCoCuTi x high-entropy alloy coatings were prepared by laser cladding. • Al 2 CrFeNiCoCuTi x coatings show excellent corrosion resistance and wear resistance. • Al 2 CrFeNiCoCuTi x coatings play a good protective effect on Q235 steel. • Ti element promotes the formation of a BCC structure in a certain extent. -- Abstract: The Al 2 CrFeNiCoCuTi x high-entropy alloy coatings were prepared by laser cladding. The structure, hardness, corrosion resistance, wear resistance and magnetic property were studied by metallurgical microscope, scanning electron microscopy with spectroscopy (SEM/EDS), X-ray diffraction, micro/Vickers hardness tester, electrochemical workstation tribometer and multi-physical tester. The result shows that, Al 2 CrFeNiCoCuTi x high-entropy alloy samples consist of the cladding zone, bounding zone, heat affected zone and substrate zone. The bonding between the cladding layer and the substrate of a good combination; the cladding zone is composed mainly of equiaxed grains and columnar crystal; the phase structure of Al 2 CrFeNiCoCuTi x high-entropy alloy coatings simple for FCC, BCC and Laves phase due to high-entropy affect. Ti element promotes the formation of a BCC structure in a certain extent. Compared with Q235 steel, the free-corrosion current density of Al 2 CrFeNiCoCuTi x high-entropy alloy coatings is reduced by 1–2 orders of magnitude, the free-corrosion potential is more “positive”. With the increasing of Ti content, the corrosion resistance of Al 2 CrFeCoCuNiTi x high-entropy alloy coatings enhanced in 0.5 mol/L HNO 3 solution. Compared with Q235 steel, the relative wear resistance of Al 2 CrFeCoCuNiTi x high-entropy alloy coatings has improved greatly; both the hardness and plasticity are affecting wear resistance. Magnetization loop shows that, Ti 0.0 high-entropy alloy is a kind of soft magnetic materials

The Synergy Effect of Ni-M (M = Mo, Fe, Co, Mn or Cr Bicomponent Catalysts on Partial Methanation Coupling with Water Gas Shift under Low H2/CO Conditions

Directory of Open Access Journals (Sweden)

Xinxin Dong

2017-02-01

Full Text Available Ni-M (M = Mo, Fe, Co, Mn or Cr bicomponent catalysts were prepared through the co-impregnation method for upgrading low H2/CO ratio biomass gas into urban gas through partial methanation coupling with water gas shift (WGS. The catalysts were characterized by N2 isothermal adsorption, X-ray diffraction (XRD, H2 temperature programmed reduction (H2-TPR, H2 temperature programmed desorption (H2-TPD, scanning electron microscopy (SEM and thermogravimetry (TG. The catalytic performances demonstrated that Mn and Cr were superior to the other three elements due to the increased fraction of reducible NiO particles, promoted dispersion of Ni nanoparticles and enhanced H2 chemisorption ability. The comparative study on Mn and Cr showed that Mn was more suitable due to its smaller carbon deposition rate and wider adaptability to various H2/CO and H2O/CO conditions, indicating its better synergy effect with Ni. A nearly 100 h, the lifetime test and start/stop cycle test further implied that 15Ni-3Mn was stable for industrial application.

An Asymmetric Supercapacitor with Mesoporous NiCo2O4 Nanorod/Graphene Composite and N-Doped Graphene Electrodes

Science.gov (United States)

Mao, J. W.; He, C. H.; Qi, J. Q.; Zhang, A. B.; Sui, Y. W.; He, Y. Z.; Meng, Q. K.; Wei, F. X.

2018-01-01

In the present work, mesoporous NiCo2O4 nanorod/graphene oxide (NiCo2O4/GO) composite was prepared by a facile and cost-effective hydrothermal method and meanwhile, N-doped graphene (N-G) was fabricated also by a hydrothermal synthesis process. NiCo2O4/GO composite and N-G were used as positive and negative electrodes for the supercapacitor, respectively, which all displayed excellent electrochemical performances. The NiCo2O4/GO composite electrode exhibited a high specific capacitance of 709.7 F g-1 at a current density of 1 A g-1 and excellent rate capability as well as good cycling performance with 84.7% capacitance retention at 6 A g-1 after 3000 cycles. A high-voltage asymmetric supercapacitor (ASC) was successfully fabricated using NiCo2O4/GO composite and N-G as the positive and negative electrodes, respectively, in 1 M KOH aqueous electrolyte. The ASC delivered a high energy density of 34.4 Wh kg-1 at a power density of 800 W kg-1 and still maintained 28 Wh kg-1 at a power density of 8000 W kg-1. Furthermore, this ASC showed excellent cycling stability with 94.3% specific capacitance retained at 5 A g-1 after 5000 cycles. The impressive results can be ascribed to the positive synergistic effects of the two electrodes. Evidently, our work provides useful information for assembling high-performance supercapacitor devices.

A Ni-P@NiCo LDH core-shell nanorod-decorated nickel foam with enhanced areal specific capacitance for high-performance supercapacitors.

Science.gov (United States)

Xing, Jiale; Du, Jing; Zhang, Xuan; Shao, Yubo; Zhang, Ting; Xu, Cailing

2017-08-14

Recently, transition metal-based nanomaterials have played a key role in the applications of supercapacitors. In this study, nickel phosphide (Ni-P) was simply combined with NiCo LDH via facile phosphorization of Ni foam and subsequent electrodeposition to form core-shell nanorod arrays on the Ni foam; the Ni-P@NiCo LDH was then directly used for a pseudocapacitive electrode. Owing to the splendid synergistic effect between Ni-P and NiCo LDH nanosheets as well as the hierarchical structure of 1D nanorods, 2D nanosheets, and 3D Ni foam, the hybrid electrode exhibited significantly enhanced electrochemical performances. The Ni-P@NiCo LDH electrode showed a high specific capacitance of 12.9 F cm -2 at 5 mA cm -2 (3470.5 F g -1 at a current density of 1.3 A g -1 ) that remained as high as 6.4 F cm -2 at a high current density of 100 mA cm -2 (1700 F g -1 at 27 A g -1 ) and excellent cycling stability (96% capacity retention after 10 000 cycles at 40 mA cm -2 ). Furthermore, the asymmetric supercapacitors (ASCs) were assembled using Ni-P@NiCo LDH as a positive electrode and activated carbon (AC) as a negative electrode. The obtained ASCs delivered remarkable energy density and power density as well as good cycling performance. The enhanced electrochemical activities open a new avenue for the development of supercapacitors.

Synthesis and characterization of NiCo{sub 2}O{sub 4} nanoplates as efficient electrode materials for electrochemical supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Kim, Taehyun [Nanomaterials and System Lab, Department of Mechatronics Engineering, Engineering College, Jeju National University, Jeju 690-756 (Korea, Republic of); Ramadoss, Ananthakumar [Nanomaterials and System Lab, Faculty of Applied Energy System, Science and Engineering College, Jeju National University, Jeju 690-756 (Korea, Republic of); Saravanakumar, Balasubramaniam; Veerasubramani, Ganesh Kumar [Nanomaterials and System Lab, Department of Mechatronics Engineering, Engineering College, Jeju National University, Jeju 690-756 (Korea, Republic of); Kim, Sang Jae, E-mail: kimsangj@jejunu.ac.kr [Nanomaterials and System Lab, Department of Mechatronics Engineering, Engineering College, Jeju National University, Jeju 690-756 (Korea, Republic of); Nanomaterials and System Lab, Faculty of Applied Energy System, Science and Engineering College, Jeju National University, Jeju 690-756 (Korea, Republic of)

2016-05-01

Highlights: • NiCo{sub 2}O{sub 4} nanoplates were synthesized through a facile approach. • The NiCo{sub 2}O{sub 4} nanoplates electrode material exhibit a specific capacitance of 332 F g{sup −1} at 5 mV s{sup −1}. • The fabricated NiCo{sub 2}O{sub 4} electrode reveals 86% retention of initial capacitance after 2000 cycles. - Abstract: In the present work, NiCo{sub 2}O{sub 4} nanoplates were prepared by a facile, low temperature, hydrothermal method, followed by thermal annealing and used supercapacitor applications. The physico-chemical characterization of as-prepared materials were investigated by means of X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR) and field emission scanning electron microscopy (FE-SEM). The electrochemical measurements demonstrate that the NiCo{sub 2}O{sub 4} nanoplates electrode (NC-5) exhibits a high specific capacitance of 332 F g{sup −1} at a scan rate of 5 mV s{sup −1} and also retained about 86% of the initial specific capacitance value even after 2000 cycles at a current density of 2.5 A g{sup −1}. These results suggest that the fabricated electrode material has huge potential as a novel electrode material for electrochemical capacitors.

Enhancement of electrochemical performance of LiNi_1_/_3Co_1_/_3Mn_1_/_3O_2 by surface modification with MnO_2

International Nuclear Information System (INIS)

Guo, Xin; Cong, Li-Na; Zhao, Qin; Tai, Ling-Hua; Wu, Xing-Long; Zhang, Jing-Ping; Wang, Rong-Shun; Xie, Hai-Ming; Sun, Li-Qun

2015-01-01

LiNi_1_/_3Co_1_/_3Mn_1_/_3O_2 is successfully coated with MnO_2 by a chemical deposition method. The X-ray diffraction (XRD), scanning electron microscope (SEM) and high resolution transmission electron microscope (HRTEM) results demonstrate that MnO_2 forms a thin layer on the surface of LiNi_1_/_3Co_1_/_3Mn_1_/_3O_2 without destroying the crystal structure of the core material. Compared with pristine LiNi_1_/_3Co_1_/_3Mn_1_/_3O_2, the MnO_2-coated sample shows enhanced electrochemical performance especially the rate capability. Even at a current density of 750 mA g"−"1, the discharge capacity of MnO_2-coated LiNi_1_/_3Co_1_/_3Mn_1_/_3O_2 is 155.15 mAh g"−"1, while that of the pristine electrode is only 132.84 mAh g"−"1 in the range of 2.5–4.5 V. The cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS) curves show that the MnO_2 coating layer reacts with Li"+ during cycling, which is responsible for the higher discharge capacity of MnO_2-coated LiNi_1_/_3Co_1_/_3Mn_1_/_3O_2. Electrochemical impedance spectroscopy (EIS) results confirmed that the MnO_2 coating layer plays an important role in reducing the charge transfer resistance on the electrolyte–electrode interfaces. - Highlights: • MnO_2 coated LiNi_1_/_3Co_1_/_3Mn_1_/_3O_2 cathode material is synthesized for the first time. • MnO_2 offers available sites for insertion of extracted lithium. • The preserved surface and crystal structures results in the improved kinetics.

Comparative Study of Electronic Structure and Magnetic Properties of Osmate Double Perovskites: Ca2FeOsO6 versus Ca2Co(Ni)OsO6

Science.gov (United States)

Samanta, Kartik; Saha-Dasgupta, Tanusri

2018-04-01

Employing density functional theory, we study the trend in the electronic and magnetic properties of 3d-5d double perovskites, upon varying the 3d element for a fixed choice of 5d element, namely Ca2BOsO6 (B = Fe/Co/Ni). While all three compounds are reported to be ferrimagnets, the magnetic transition temperature of Ca2FeOsO6 is reported to be 2-2.4 times larger than that of Ca2CoOsO6 or Ca2NiOsO6. Our first-principles study provides microscopic insight into this trend. This trend is found to be caused by the downward shift in the position of d level energies of the B site element with respect to that of the Os t2g level upon moving across the 3d series from Fe to Co and Ni. This in turn changes the nominal valence of the Os ion from 5+ in Ca2FeOsO6 to 6+ in Ca2CoOsO6 and Ca2NiOsO6, resulting in differing superexchange paths between Ca2FeOsO6 and Ca2Co(Ni)OsO6, and additionally enabling the hybridization-mechanism-driven magnetism in Ca2FeOsO6. These together significantly enhance the magnetic transition temperature in Ca2FeOsO6 compared with that in Ca2Co(Ni)OsO6.

1D Co2.18Ni0.82Si2O5(OH)4 architectures assembled by ultrathin nanoflakes for high-performance flexible solid-state asymmetric supercapacitors

Science.gov (United States)

Zhao, Junhong; Zheng, Mingbo; Run, Zhen; Xia, Jing; Sun, Mengjun; Pang, Huan

2015-07-01

1D Co2.18Ni0.82Si2O5(OH)4 architectures assembled by ultrathin nanoflakes are synthesized for the first time by a hydrothermal method. We present a self-reacting template method to synthesize 1D Co2.18Ni0.82Si2O5(OH)4 architectures using Ni(SO4)0.3(OH)1.4 nanobelts. A high-performance flexible asymmetric solid-state supercapacitor can be successfully fabricated based on the 1D Co2.18Ni0.82Si2O5(OH)4 architectures and graphene nanosheets. Interestingly, the as-assembled 1D Co2.18Ni0.82Si2O5(OH)4 architectures//Graphene nanosheets asymmetric solid-state supercapacitor can achieve a maximum energy density of 0.496 mWh cm-3, which is higher than most of reported solid state supercapacitors. Additionally, the device shows high cycle stability for 10,000 cycles. These features make the 1D Co2.18Ni0.82Si2O5(OH)4 architectures as one of the most promising candidates for high-performance energy storage devices.

SFG investigation of adsorbed CO and NO on NiO(111) surface

Energy Technology Data Exchange (ETDEWEB)

Bandara, Athula; Dobashi, Shinsaku; Kubota, Jun; Onda, Ken; Wada, Akihide; Domen, Kazunari; Hirose, Chiaki [Tokyo Inst. of Tech., Yokohama (Japan). Research Lab. of Resources Utilization; Kano, S.S.

1997-07-01

Adsorption structures of CO and NO on the NiO(111) film grown on Ni(111) crystal have been investigated by sum frequency generation (SFG) spectroscopy and infrared reflection absorption spectroscopy (IRAS). The CO stretching band of adsorbed CO on NiO(111) was observed at 2144 cm{sup -1} on the SFG spectra for both p- and s-polarized visible light. However, adsorbed NO on NiO(111) was observed at 1805 cm{sup -1} on the SFG spectra only for the p-polarized visible light. The results suggest that the adsorbed CO molecule was tilted from the surface normal but the NO molecule was perpendicular to the surface. These orientations of CO and NO reflect the surface structure of NiO(111) which has (2 x 2)-reconstructed microfacets. Adsorption of CO on Ni(111) instead of NiO(111) was also examined by SFG and IRAS. Absorption bands due to linear and bridged CO were observed at 2076 and 1918 cm{sup -1}, respectively, by IRAS. On the other hand, the linear CO molecules on Ni(111) gave an SFG peak at 2076 cm{sup -1} only for the p-polarized visible light indicating the CO molecules are perpendicular to the surface, and bridged CO molecules did not give any SFG signal. The absence of the bridged CO signal is believed to be due to the smaller Raman tensor of bridged CO. (author)

SFG investigation of adsorbed CO and NO on NiO(111) surface

International Nuclear Information System (INIS)

Bandara, Athula; Dobashi, Shinsaku; Kubota, Jun; Onda, Ken; Wada, Akihide; Domen, Kazunari; Hirose, Chiaki; Kano, S.S.

1997-01-01

Adsorption structures of CO and NO on the NiO(111) film grown on Ni(111) crystal have been investigated by sum frequency generation (SFG) spectroscopy and infrared reflection absorption spectroscopy (IRAS). The CO stretching band of adsorbed CO on NiO(111) was observed at 2144 cm -1 on the SFG spectra for both p- and s-polarized visible light. However, adsorbed NO on NiO(111) was observed at 1805 cm -1 on the SFG spectra only for the p-polarized visible light. The results suggest that the adsorbed CO molecule was tilted from the surface normal but the NO molecule was perpendicular to the surface. These orientations of CO and NO reflect the surface structure of NiO(111) which has (2 x 2)-reconstructed microfacets. Adsorption of CO on Ni(111) instead of NiO(111) was also examined by SFG and IRAS. Absorption bands due to linear and bridged CO were observed at 2076 and 1918 cm -1 , respectively, by IRAS. On the other hand, the linear CO molecules on Ni(111) gave an SFG peak at 2076 cm -1 only for the p-polarized visible light indicating the CO molecules are perpendicular to the surface, and bridged CO molecules did not give any SFG signal. The absence of the bridged CO signal is believed to be due to the smaller Raman tensor of bridged CO. (author)

In situ preparation of NiS2/CoS2 composite electrocatalytic materials on conductive glass substrates with electronic modulation for high-performance counter electrodes of dye-sensitized solar cells

Science.gov (United States)

Li, Faxin; Wang, Jiali; Zheng, Li; Zhao, Yaqiang; Huang, Niu; Sun, Panpan; Fang, Liang; Wang, Lei; Sun, Xiaohua

2018-04-01

The electrocatalytic composite materials of honeycomb structure NiS2 nanosheets loaded with metallic CoS2 nanoparticles are in situ prepared on F doped SnO2 conductive glass (FTO) substrates used as counter electrodes of DSSCs through chemical bath deposition (CBD) and sulfidizing process. Single crystalline NiS2 honeycomb structure array lay a foundation for the large surface area of NiS2/CoS2 composite CEs. The formed NiS2/CoS2 nanointerface modulates electronic structure of composite CEs from the synergetic interactions between CoS2 nanoparticles and NiS2 nanosheets, which dramatically improves the electrocatalytic activity of NiS2/CoS2 composite CEs; Metallic CoS2 nanoparticles covering NiS2 nanosheets electrodes adjusts the electrodes' structure and then reduces the series resistance (Rs) and the Nernst diffusion resistance (Zw) of counter electrodes. The improvement of these areas greatly enhances the electrocatalytic performance of CEs and the short circuit current density (Jsc) and Fill factor (FF) of DSSCs. Impressively, the DSSC based on NiS2/CoS2-0.1 CE shows the best photovoltaic performance with photovoltaic conversion efficiency of 8.22%, which is 24.36% higher than that (6.61%) of the DSSC with Pt CE. And the NiS2/CoS2-0.1 CE also displays a good stability in the iodine based electrolyte. This work indicates that rational construction of composite electrocatalytic materials paves an avenue for high-performance counter electrodes of DSSCs.

Biperiodic oscillatory coupling with the thickness of an embedded Ni layer in Co/Cu/Co/Ni/Co (100) and selection rules for the periods

NARCIS (Netherlands)

de Vries, J.J.; Vorst, van de M.T.H.; Johnson, M.T.; Jungblut, R.; Reinders, A.; Bloemen, P.J.H.; Coehoorn, R.; Jonge, de W.J.M.

1996-01-01

A biperiodic oscillation of the strength of the antiferromagnetic interlayer coupling as a function of the thickness of an embedded Ni layer has been observed in an epitaxial Cu(100)/Co/Cu/Co/Ni/Co sample with the Cu interlayer and the Ni layer in the form of wedges. As the effect originates from

Phase equilibria and stability of the B2 phase in the Ni-Mn-Al and Co-Mn-Al systems

International Nuclear Information System (INIS)

Kainuma, R.; Ise, M.; Ishikawa, K.; Ohnuma, I.; Ishida, K.

1998-01-01

The phase equilibria and ordering reactions in the composition region up to 50 at.% Al have been investigated in the Ni-Mn-Al and Co-Mn-Al systems at temperatures in the interval 850-1200 C mainly by the diffusion couple method. The compositions of the γ (A1: fcc-Ni, -Co, γ-Mn), γ' (L1 2 : Ni 3 Al), β (B2: NiAl, CoAl, NiMn), β-Mn (A13: β-Mn type), δ-Mn (A2: bcc-Mn) and ε (A3: hcp-(Mn, Al)) phases in equilibrium and the critical boundaries of the A2/B2 continuous ordering transition in the bcc phase region have been determined. It is shown that in the Mn-rich portion of the ternary systems both continuous and discontinuous A2 to B2 ordering transitions exist. The A2+B2 two-phase region in the isothermal sections has a lenticular shape and exists over a wide temperature range. The phase equilibria between the γ, γ', β, β-Mn, δ-Mn and ε phases are presented and the stability of the ordered bcc aluminides is discussed. (orig.)

High catalytic activity and stability of Ni/CexZr1-xO2/MSU-H for CH4/CO2 reforming reaction

Science.gov (United States)

Chang, Xiaoqian; Liu, Bingsi; Xia, Hong; Amin, Roohul

2018-06-01

How to reduce emission of CO2 as greenhouse gases, which resulted in global warming, is of very important significance. A series of Ni/CexZr1-xO2/MSU-H catalysts was prepared by means of hexagonally ordered mesoporous MSU-H with thermal and hydrothermal stabilities, which is cheap and can be synthesized in the large scale. The 10%Ni/Ce0.75Zr0.25O2/MSU-H catalyst presents high catalytic activity, stability and the ability of coke-resistance for CH4/CO2 reforming reaction due to high SBET (428 m2/g) and smaller Nio nanoparticle size (3.14 nm). The high dispersed Nio nanoparticles over MSU-H promoted the decomposition of CH4 and the carbon species accumulated on active Nio sites reacting with crystal lattice oxygen in Ce0.75Zr0.25O2 to form CO molecules. In the meantime, the remained oxygen vacancies on the interface between Nio and Ce0.75Zr0.25O2 could be supplemented via CO2. HRTEM images and XRD results of Ni/Ce0.75Zr0.25O2/MSU-H verified that high dispersion of Ni nanoparticles over Ni/Ce0.75Zr0.25O2/MSU-H correlated closely with the synergistic action between Ce0.75Zr0.25O2 and MSU-H as well as hexagonally ordered structure of MSU-H, which can provide effectively the oxygen storage capacity and inhibit the formation of coke.

FY1995 study of highly efficient power generation system based on chemical-looping combustion; 1995 nendo chemical loop nenshoho ni yoru kokoritsu hatsuden system no kaihatsu ni kansuru kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-03-01

Synthesis of highly efficient and low emission power generation plant with chemical-looping combustion using various fuels such as natural gas, coal gas and hydrogen. Development of new looping materials with suitable reactivity, regenerative ability, and avoidance of carbon deposition. To obtain the design data for demo-plant by using the current experiment high- pressure fixed bed reactor. From the viewpoint of application of the proposed power generation system with chemical-looping combustion, the following main results were obtained. 1. New looping materials: NiO/NiAl{sub 2}O{sub 4}, CoO-NiO/YSZ, and Co{sub 3}O{sub 4}/CoAl{sub 2}O{sub 4}. These materials have high reactivity, repeatability, and avoidance of carbon deposition which play important roles in application of this new combustor. 2. NO{sub x} formation can be completely avoided; both fuel NO{sub x} in reduction reactor for coal gas as fuel and thermal NO{sub x} in oxidation reactor. 3. It is identified from the experiment using fixed bed reactor with the elevated pressure that NiO/NiAl{sub 2}O{sub 4} is a suitable material for coal gas or hydrogen. These promising results have provided valuable data for industrial application. (NEDO)

Mechanosynthesis of MFe2O4 (M = Co, Ni, and Zn Magnetic Nanoparticles for Pb Removal from Aqueous Solution

Directory of Open Access Journals (Sweden)

America R. Vazquez-Olmos

2016-01-01

Full Text Available Adsorption of Pb(II from aqueous solution using MFe2O4 nanoferrites (M = Co, Ni, and Zn was studied. Nanoferrite samples were prepared via the mechanochemical method and were characterized by X-ray powder diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, micro-Raman, and vibrating sample magnetometry (VSM. XRD analysis confirms the formation of pure single phases of cubic ferrites with average crystallite sizes of 23.8, 19.4, and 19.2 nm for CoFe2O4, NiFe2O4, and ZnFe2O4, respectively. Only NiFe2O4 and ZnFe2O4 samples show superparamagnetic behavior at room temperature, whereas CoFe2O4 is ferromagnetic. Kinetics and isotherm adsorption studies for adsorption of Pb(II were carried out. A pseudo-second-order kinetic describes the sorption behavior. The experimental data of the isotherms were well fitted to the Langmuir isotherm model. The maximum adsorption capacity of Pb(II on the nanoferrites was found to be 20.58, 17.76, and 9.34 mg·g−1 for M = Co, Ni, and Zn, respectively.

Measurement and analyses of molten Ni-Co alloy density

Institute of Scientific and Technical Information of China (English)

XIAO Feng; K. MUKAI; FANG Liang; FU Ya; YANG Ren-hui

2006-01-01

With the advent of powerful mathematical modeling techniques for material phenomena, there is renewed interest in reliable data for the density of the Ni-based superalloys. Up to now, there has been few report on the density of molten Ni-Co alloy.In order to obtain more accurate density data for molten Ni-Co alloy, the density of molten Ni-Co alloy was measured with a modified sessile drop method, and the accommodation of different atoms in molten Ni-Co alloy was analyzed. The density of alloy is found to decrease with increasing temperature and Co concentration in the alloy. The molar volume of molten Ni-Co alloy increases with increasing Co concentration. The molar volume of Ni-Co alloy determined shows a positive deviation from the linear molar volume, and the deviation of molar volume from ideal mixing increases with increasing Co concentration over the experimental concentration range.

One-pot synthesis of CoNiO{sub 2} single-crystalline nanoparticles as high-performance electrode materials of asymmetric supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Du, Weimin, E-mail: dwmchem@163.com; Gao, Yanping; Tian, Qingqing; Li, Dan; Zhang, Zhenhu; Guo, Jiaojiao [Anyang Normal University, College of Chemistry and Chemical Engineering (China); Qian, Xuefeng [Shanghai Jiao Tong University, School of Chemistry and Chemical Technology (China)

2015-09-15

A facile one-pot solvothermal method has been developed to synthesize CoNiO{sub 2} single-crystalline nanoparticles. Crystal phase, morphology, crystal lattice, and composition of the obtained products were characterized by X-ray diffraction, scanning electron microscope, high-resolution transmission electron microscopy, and energy-dispersive X-ray analysis, respectively. Results revealed that the as-synthesized CoNiO{sub 2} nanoparticles belong to cubic structure with narrow size-distribution (8–10 nm). Subsequently, new asymmetric supercapacitors were successfully assembled with CoNiO{sub 2} nanoparticles as positive electrode and activated carbon as negative electrode. The electrochemical results show that asymmetric supercapacitors based on CoNiO{sub 2} nanoparticles possess excellent supercapacitor properties, i.e., a stable electrochemical window of 0–1.7 V, higher energy density of 24.0 Wh/kg at a power density of 415.4 W/kg, and excellent cycling stability (96.8 % capacitance retention after 5000 charge–discharge cycles). Meanwhile, both a light-emitting diode and a mini fan can be powered by two series connection asymmetric supercapacitors. These results imply that the present asymmetric supercapacitors based on CoNiO{sub 2} nanoparticles possess the promising potential application in the field of high-performance energy storage.

Porous NiCo{sub 2}S{sub 4}-halloysite hybrid self-assembled from nanosheets for high-performance asymmetric supercapacitor applications

Energy Technology Data Exchange (ETDEWEB)

Chai, Hui, E-mail: huichmails@163.com; Dong, Hong; Wang, Yucheng; Xu, Jiayu; Jia, Dianzeng

2017-04-15

Highlights: • The NiCo{sub 2}S{sub 4}-HL nanomaterial is achieved via two-step hydrothermal approach. • The unique structures are assembled self-assembly by nanosheets. • The obtained electrode exhibits high capacitance and excellent retention. • An asymmetric supercapacitor also displays high energy density and outstanding cycling stability. • The high-performance of the device is possibly due to the introduction of HL and formation of composed nanosheets. - Abstract: The porous nanostructures have drawn considerable attention because of their abundant pore volume and unique properties that provide outstanding performance in catalysis and energy storage applications. This study proposes the growth mechanism of porous NiCo{sub 2}S{sub 4} composited with halloysite (HL) via a self-assembly method using halloysite as a template and component. Electrochemical tests showed that the NiCo{sub 2}S{sub 4}-HL exhibited an ultrahigh specific capacitance (Csp) (589C g{sup −1} at 1A g{sup −1}) and good cycle stability (Csp retention of 86% after 1000 cycles). The desirable capacitive performance of the NiCo{sub 2}S{sub 4}-HL can be attributed to the large specific surface area and short diffusion path for electrons and ions in the hierarchical porous structure. The superior electrochemical performances with the energy density of 35.48 W h kg{sup −1} at a power density of 199.9 W kg{sup −1} were achieved in an assembled aqueous asymmetric supercapacitor (ASC) device using NiCo{sub 2}S{sub 4}-HL as a positive electrode and N-doped graphene (NG) as a negative electrode. Moreover, the NiCo{sub 2}S{sub 4}-HL//NG asymmetric supercapacitor achieved outstanding cycle stability (also retained 83.2% after 1700 cycles). The high-performance of the ASC device will undoubtedly make the porous NiCo{sub 2}S{sub 4}-HL as potential electrode materials attractive in energy storage systems.

Effect of interface intermixing on giant magnetoresistance in NiFe/Cu and Co/NiFe/Co/Cu multilayers

International Nuclear Information System (INIS)

Nagamine, L.C.C.M.; Biondo, A.; Pereira, L.G.; Mello, A.; Schmidt, J.E.; Chimendes, T.W.; Cunha, J.B.M.; Saitovitch, E.B.

2003-01-01

This article reports on the important influence of the spontaneously built-in paramagnetic interfacial layers on the magnetic and magnetoresistive properties of NiFe/Cu and Co/NiFe/Co/Cu multilayers grown by magnetron sputtering. A computational simulation, based on a semiclassical model, has been used to reproduce the variations of the resistivity and of the magnetoresistance (MR) amplitude with the thickness of the NiFe, Cu, and Co layers. We showed that the compositionally intermixed layers at NiFe/Cu interfaces, which are paramagnetic, reduce the flow of polarized electrons and produce a masking on the estimated mean-free path of both types of electrons due to the reduction of their effective values, mainly for small NiFe thickness. Moreover, the transmission coefficients for the electrons decrease when Fe buffer layers are replaced by NiFe ones. This result is interpreted in terms of the variations of the interfacial intermixing and roughness at the interfaces, leading to an increase of the paramagnetic interfacial layer thickness. The effect provoked by Co deposition at the NiFe 16 A/Cu interfaces has also been investigated. The maximum of the MR amplitudes was found at 5 A of Co, resulting in the quadruplication of the MR amplitude. This result is partially attributed to the interfacial spin-dependent scattering due to the increase of the magnetic order at interfaces. Another effect observed here was the increase of the spin-dependent scattering events in the bulk NiFe due to a larger effective NiFe thickness, since the paramagnetic interfacial layer thickness is decreased

3d-metal doping (Fe,Co,Ni,Zn) of the high Tc perovskite YBa2Cu3O(7-y)

International Nuclear Information System (INIS)

Tarascon, J.M.; Barboux, P.; Greene, L.H.; Hull, G.W.; Bagley, B.G.

1988-01-01

The structural, magnetic and superconducting properties of the mixed compounds YBa 2 Cu(3-x)M(x)O(7-y) (M = Ni,Zn,Fe, and Co) are reported. Values of y, determined by titration, are found to be dependent on the nature and amount of the doping. The range of solubility is greater for the Fe and Co compounds (x = 1) than for those with Ni or Zn (x = 0.3). The undoped material is orthorhombic and remains orthorhombic after substitution for Cu by Ni or Zn, whereas a tetragonal phase is observed when Fe, Co are substituted for Cu. DC resistance and AC susceptibility measurements show that Tc is depressed from 90K (x = 0) to 45K (x = 0.2) for both the Ni- and Zn-doped compounds, and Tc is destroyed in the Fe- and Co-doped compounds when x reaches 0.4. It is suggested that a valence of two be assigned to the Ni and Zn and three to the Fe and Co ions. 8 references

Controllable Hydrothermal Conversion from Ni-Co-Mn Carbonate Nanoparticles to Microspheres

Directory of Open Access Journals (Sweden)

Yanqing Tang

2016-11-01

Full Text Available Starting from Ni-Co-Mn carbonate nanoparticles prepared by microreaction technology, uniform spherical particles of Ni1/3Co1/3Mn1/3CO3 with a size of 3–4 μm were obtained by a controllable hydrothermal conversion with the addition of (NH42CO3. Based on characterizations on the evolution of morphology and composition with hydrothermal treatment time, we clarified the mechanism of this novel method as a dissolution-recrystallization process, as well as the effects of (NH42CO3 concentration on the morphology and composition of particles. By changing concentrations and the ratio of the starting materials for nano-precipitation preparation, we achieved monotonic regulation on the size of the spherical particles, and the synthesis of Ni0.4Co0.2Mn0.4CO3 and Ni0.5Co0.2Mn0.3CO3, respectively. In addition, the spherical particles with a core-shell structure were preliminarily verified to be available by introducing nano-precipitates with different compositions in the hydrothermal treatment in sequence.

CuCo_2O_4 flowers/Ni-foam architecture as a battery type positive electrode for high performance hybrid supercapacitor applications

International Nuclear Information System (INIS)

Vijayakumar, Subbukalai; Nagamuthu, Sadayappan; Ryu, Kwang-Sun

2017-01-01

Graphical abstract: The Ni- foam supported CuCo_2O_4 flowers exhibits a high specific capacity with superior long term cyclic stability. - Highlights: • This paper reports the hydrothermal preparation of CuCo_2O_4 flowers on Ni-foam. • The CuCo_2O_4 flowers exhibits maximum specific capacity of 645.1C g"−"1. • After 2000 cycles, 109% of the initial specific capacity was retained. - Abstract: The battery type CuCo_2O_4 electrode was evaluated as a positive electrode material for its hybrid supercapacitor applications. CuCo_2O_4 flowers were prepared on Ni-foam through a simple hydrothermal process and post calcination treatment. The structure and morphology of the CuCo_2O_4 flowers/Ni-foam was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy. FESEM clearly revealed the flower-like morphology, which was composed of large number of petals. The length and width of the petals ranged from approximately 5–8 μm and approximately 50–150 nm, respectively. The CuCo_2O_4 flowers/Ni-foam electrode was employed for electrochemical characterization for hybrid supercapacitor applications. The specific capacity of the CuCo_2O_4 flower-like electrode was 692.4C g"−"1 (192.3 mA h g"−"1) at a scan rate of 5 mV s"−"1. The flower-like CuCo_2O_4 electrode exhibited a maximum specific capacity of 645.1C g"−"1 (179.2 mA h g"−"1) at a specific current of 1 A g"−"1 and good long term cyclic stability. The high specific capacity, good cyclic stability, and low internal and charge transfer resistance of the CuCo_2O_4 flowers/Ni-foam electrode confirmed the suitability of the prepared material as a positive electrode for hybrid supercapacitor applications.

Determination of standard Ghibbs free energy of formation of NiW sub 2 B sub 2 and activity of Ni-W binary system by EMF measurement. Kidenryokuho ni yoru NiW sub 2 B sub 2 no hyojun seisei Gibbs jiyu energy to Ni-W 2 seibunkei no katsuryo no sokutei

Energy Technology Data Exchange (ETDEWEB)

Kayama, Koichiro; Hashimoto, Yasuhiko; Suzuki, Kenji; Matsuo, Hideki (Himeji Inst. of Tech., Hyogo (Japan) Fukushin Electric Co., Ltd., Hyogo (Japan))

1989-12-25

NiW {sub 2} B {sub 2} (M phase), existing in trinary Ni-W-B system, was measured in standard Gibbs free energy (GF) of formation in the temperature range from 1273K to 1423K by an electromotive force method (EMF) with use of solid oxide electrolyte. First, oxide phase in equilibrium with three-phase M-W-Ni solid solution region was confirmed to be B {sub 2} O {sub 3}. Binary Ni-W system solid solution in equilibrium with M phase and W phase is constant in composition with Ni-16.4mo1%W in the above temperature range. WO {sub 2} and WO {sub 2.72} were actually measured in GF. As Ni-W solid solution is in equilibrium with WO {sub 2} and WO {sub 2.72}, binary Ni-W system was measured in activity by the EMF, and Ni-16.4mo1%W solid solution was calculated in GF of mixing by use of the above measured GF of WO {sub 2} and WO {sub 2.72}. Finally with use of sample in M-W-Ni solid solution region, M phase was calculated in GF by the EMF. The result of those calculations were expressed with experimental formulas. 19 refs., 10 figs., 3 tabs.

In situ growth of NiCo2S4 nanotube arrays on Ni foam for supercapacitors: Maximizing utilization efficiency at high mass loading to achieve ultrahigh areal pseudocapacitance

Science.gov (United States)

Chen, Haichao; Jiang, Jianjun; Zhang, Li; Xia, Dandan; Zhao, Yuandong; Guo, Danqing; Qi, Tong; Wan, Houzhao

2014-05-01

Self-standing NiCo2S4 nanotube arrays have been in situ grown on Ni foam by the anion-exchange reaction and directly used as the electrode for supercapacitors. The NiCo2S4 nanotube in the arrays effectively reduces the inactive material and increases the electroactive surface area because of the ultrathin wall, which is quite competent to achieve high utilization efficiency at high electroactive materials mass loading. The NiCo2S4 nanotube arrays hybrid electrode exhibits an ultrahigh specific capacitance of 14.39 F cm-2 at 5 mA cm-2 with excellent rate performance (67.7% retention for current increases 30 times) and cycling stability (92% retention after 5000 cycles) at a high mass loading of 6 mg cm-2. High areal capacitance (4.68 F cm-2 at 10 mA cm-2), high energy density (31.5 Wh kg-1 at 156.6 W kg-1) and high power density (2348.5 W kg-1 at 16.6 Wh kg-1) can be achieved by assembling asymmetric supercapacitor with reduced graphene oxide at a total active material mass loading as high as 49.5 mg. This work demonstrates that NiCo2S4 nanotube arrays structure is a superior electroactive material for high-performance supercapacitors even at a mass loading of potential application-specific scale.

Carbonato-bridged Ni(II)2Ln(III)2 (Ln(III) = Gd(III), Tb(III), Dy(III)) complexes generated by atmospheric CO2 fixation and their single-molecule-magnet behavior: [(μ4-CO3)2{Ni(II)(3-MeOsaltn)(MeOH or H2O)Ln(III)(NO3)}2]·solvent [3-MeOsaltn = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato].

Science.gov (United States)

Sakamoto, Soichiro; Fujinami, Takeshi; Nishi, Koshiro; Matsumoto, Naohide; Mochida, Naotaka; Ishida, Takayuki; Sunatsuki, Yukinari; Re, Nazzareno

2013-06-17

Atmospheric CO2 fixation of [Ni(II)(3-MeOsaltn)(H2O)2]·2.5H2O [3-MeOsaltn = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato], Ln(III)(NO3)3·6H2O, and triethylamine occurred in methanol/acetone, giving a first series of carbonato-bridged Ni(II)2Ln(III)2 complexes [(μ4-CO3)2{Ni(II)(3-MeOsaltn)(MeOH)Ln(III)(NO3)}2] (1Gd, 1Tb, and 1Dy). When the reaction was carried out in acetonitrile/water, it gave a second series of complexes [(μ4-CO3)2{Ni(II)(3-MeOsaltn)(H2O)Ln(III)(NO3)}2]·2CH3CN·2H2O (2Gd, 2Tb, and 2Dy). For both series, each Ni(II)2Ln(III)2 structure can be described as two di-μ-phenoxo-bridged Ni(II)Ln(III) binuclear units bridged by two carbonato CO3(2-) units to form a carbonato-bridged (μ4-CO3)2{Ni(II)2Ln(III)2} structure. The high-spin Ni(II) ion has octahedral coordination geometry, and the Ln(III) ion is coordinated by O9 donor atoms from Ni(II)(3-MeOsaltn), bidentate NO3(-), and one and two oxygen atoms of two CO3(2-) ions. The NO3(-) ion for the first series roughly lie on Ln-O(methoxy) bonds and are tilted toward the outside, while for the second series, the two oxygen atoms roughly lie on one of the Ln-O(phenoxy) bonds due to the intramolecular hydrogen bond. The temperature-dependent magnetic susceptibilities indicated a ferromagnetic interaction between the Ni(II) and Ln(III) ions (Ln(III) = Gd(III), Tb(III), Dy(III)) for all of the complexes, with a distinctly different magnetic behavior between the two series in the lowest-temperature region due to the Ln(III)-Ln(III) magnetic interaction and/or different magnetic anisotropies of the Tb(III) or Dy(III) ion. Alternating-current susceptibility measurements under the 0 and 1000 Oe direct-current (dc) bias fields showed no magnetic relaxation for the Ni(II)2Gd(III)2 complexes but exhibited an out-of-phase signal for Ni(II)2Tb(III)2 and Ni(II)2Dy(III)2, indicative of slow relaxation of magnetization. The energy barriers, Δ/kB, for the spin flipping were estimated from the Arrhenius

Application of Chemical Doping and Architectural Design Principles To Fabricate Nanowire Co2Ni3ZnO8 Arrays for Aqueous Asymmetric Supercapacitors.

Science.gov (United States)

Liu, Qi; Yang, Bin; Liu, Jingyuan; Yuan, Yi; Zhang, Hongsen; Liu, Lianhe; Wang, Jun; Li, Rumin

2016-08-10

Electrode materials derived from transition metal oxides have a serious problem of low electron transfer rate, which restricts their practical application. However, chemically doped graphene transforms the chemical bonding configuration to enhance electron transfer rate and, therefore, facilitates the successful fabrication of Co2Ni3ZnO8 nanowire arrays. In addition, the Co2Ni3ZnO8 electrode materials, considered as Ni and Zn ions doped into Co3O4, have a high electron transfer rate and electrochemical response capability, because the doping increases the degree of crystal defect and reaction of Co/Ni ions with the electrolyte. Hence, the Co2Ni3ZnO8 electrode exhibits a high rate property and excellent electrochemical cycle stability, as determined by electrochemical analysis of the relationship between specific capacitance, IR drop, Coulomb efficiency, and different current densities. From the results of a three-electrode system of electrochemical measurement, the Co2Ni3ZnO8 electrode demonstrates a specific capacitance of 1115 F g(-1) and retains 89.9% capacitance after 2000 cycles at a current density of 4 A g(-1). The energy density of the asymmetric supercapacitor (AC//Co2Ni3ZnO8) is 54.04 W h kg(-1) at the power density of 3200 W kg(-1).

In situ XAS study of Li{sub x}Ni{sub 0.7}Fe{sub 0.15}Co{sub 0.15}O{sub 2} cathode material

Energy Technology Data Exchange (ETDEWEB)

Mansour, A.N. [Naval Surface Warfare Center, West Bethesda, MD (United States); Croguennec, L.; Prado, G.; Delmas, C. [Inst. de Chimie de la Matiere Condensee de Bordeaus-CNRS and Ecole Nationale Superieure de Chimie et Physique de Bordeaux, Pesssac Cedex (France)

2001-03-01

We have examined the oxidation states and local atomic structures of Ni, Fe, and Co in Li{sub x}Ni{sub 0.7}Fe{sub 0.15}Co{sub 0.15}O{sub 2} as a function of Li content during the first charge in a Li//Li{sub x}Ni{sub 0.7}Fe{sub 0.15}Co{sub 0.}1{sub 5O2} nonaqueous cell. We show that the composition of the material in the pristine state is more accurately described by Li{sub 0.95}Ni(II){sub 0.09}Ni(III){sub 0.66}Fe(III){sub 0.15}Co(III){sub 0.15}O{sub 2}. Half Ni(II) resides in Li-vacant sites. Both Fe and Co substitute for Ni within the NiO{sub 2} slabs with no significant amounts of Fe or Co that can be attributed to Li-vacant sites. The local structure parameters are consistent with oxidation states observed on the basis of the XANES data. The Ni {kappa}-edge energy continuously shifts to a higher energy with decrease in Li content due to oxidation of Ni( II) to Ni( III) and Ni( III) to Ni( IV). After the complete oxidation of Ni( III) to Ni( IV), the Fe KAPPA(-edge energy begins to increase with further decrease in Li content indicating the oxidation of Fe( III) to Fe( IV). The Co )KAPPA-edge energy at half-height, on the other hand, is unchanged during the whole range of Li de-intercalation indicating that no significant change in the oxidation state of Co occurs upon the complete removal of Li. (au)

Porous Ni-Co-Mn oxides prisms for high performance electrochemical energy storage

Science.gov (United States)

Zhao, Jianbo; Li, Man; Li, Junru; Wei, Chengzhen; He, Yuyue; Huang, Yixuan; Li, Qiaoling

2017-12-01

Porous Ni-Co-Mn oxides prisms have been successfully synthesized via a facile route. The process involves the preparation of nickel-cobalt-manganese acetate hydroxide by a simple co-precipitation method and subsequently the thermal treatment. The as-synthesized Ni-Co-Mn oxides prisms had a large surface area (96.53 m2 g-1) and porous structure. As electrode materials for supercapacitors, porous Ni-Co-Mn oxides prisms showed a high specific capacitance of 1623.5 F g-1 at 1.0 A g-1. Moreover, the porous Ni-Co-Mn oxides prisms were also employed as positive electrode materials to assemble flexible solid-state asymmetric supercapacitors. The resulting flexible device had a maximum volumetric energy density (0.885 mW h cm-3) and power density (48.9 mW cm-3). Encouragingly, the flexible device exhibited good cycling stability with only about 2.2% loss after 5000 charge-discharge cycles and excellent mechanical stability. These results indicate that porous Ni-Co-Mn oxides prisms have the promising application in high performance electrochemical energy storage.

Electrodeposition and characterization of nanocrystalline CoNiFe films

Energy Technology Data Exchange (ETDEWEB)

Chen, Y.; Wang, Q.P. [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Cai, C. [School of Chemistry and chemical engineering, Ningxia University, Yinchuan 750021 (China); Yuan, Y.N. [Department of Materials and Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Cao, F.H. [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Zhang, Z., E-mail: eaglezzy@zjuem.zju.edu.cn [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Zhang, J.Q. [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); State Key Laboratory for Corrosion and Protection of Metals, Shenyang 110016 (China)

2012-02-29

Nanocrystalline Co{sub 45}Ni{sub 10}Fe{sub 24} films have been fabricated using cyclic voltammetry technique from the solutions containing sulfate, then characterized by scanning electron microscopy, X-ray diffraction and vibrating sample magnetometer. Meanwhile, Electrochemical Impedance Spectroscopy technique has been employed to probe into the nucleation/growth behavior of Co{sub 45}Ni{sub 10}Fe{sub 24} films. The results show that, the obtained Co{sub 45}Ni{sub 10}Fe{sub 24} film possesses low coercivity of 973.3 A/m and high saturation magnetic flux density of 1.59 Multiplication-Sign 10{sup 5} A/m. Under the experimental conditions, the nucleation/growth process of Co{sub 45}Ni{sub 10}Fe{sub 24} films is mainly under activation control. With the increase of the applied cathodic potential bias, the charge transfer resistance for CoNiFe deposition decreases exponentially. - Highlights: Black-Right-Pointing-Pointer Nanocrystalline Co{sub 45}Ni{sub 10}Fe{sub 24} film is obtained using cyclic voltammetry technique. Black-Right-Pointing-Pointer Nanocrystalline Co{sub 45}Ni{sub 10}Fe{sub 24} possesses low coercivity of 973.3 A/m. Black-Right-Pointing-Pointer Nanocrystalline Co{sub 45}Ni{sub 10}Fe{sub 24} possesses high saturation magnetic flux density. Black-Right-Pointing-Pointer The nucleation/growth process of CoNiFe films is mainly under activation control. Black-Right-Pointing-Pointer The charge transfer resistance for CoNiFe deposition decreases exponentially.

A Study of CO2 Methanation over Ni-Based Catalysts Supported by CNTs with Various Textural Characteristics

OpenAIRE

Yanyan Feng; Wen Yang; Wei Chu

2015-01-01

This work studied the influence of textural characteristics of CNTs on catalytic performance of Ni/CNTs for CO2 methanation. The CNTs supports were prepared by chemical vapor deposition method using Ni/MgO catalysts, and acetonitrile and ethanol were used as carbon sources, respectively. The Ni/CNTs catalysts were prepared via impregnation method and characterized by X-ray diffraction (XRD), N2 adsorption/desorption, and temperature-programmed reduction (H2-TPR) techniques. The results indica...

Improve electrochemical performance of CeO2 surface modification LiNi0.80Co0.15Al0.05O2 cathode material

Science.gov (United States)

Xia, Shubiao; Zhang, Yingjie; Dong, Peng; Zhang, Yannan

2014-06-01

Lithium ion battery cathode material LiNi0.8Co0.15Al0.05O2 cathode has successfully prepared by co-precipitation. CeO2 surface modification has improved LiNi0.80Co0.15Al0.05O2 electrochemical performance use sol-gel method and subsequent heat treatment at 600 °C for 5 h. Different to other conventional coating material, CeO2 coating layer can not only inhibit the reaction of the electrode and the electrolyte, but also can reduce the impedance of electron transfer due to its high conductivity, and inhibit the production of Ni2+ because of its high oxidation. The surface-modified and pristine LiNi0.80Co0.15Al0.05O2 powders are characterized by XRD, SEM, TEM, XPS, CV and DSC. When CeO2 coating is 0.02% (mole ratio), contrast to pristine NCA, the CeO2-coated NCA cathode exhibits no decrease in its initial specific capacity of 184 mAh g -1 (at 0.2 C) and excellent capacity retention (86% of its initial capacity at 1 C) between 2.75 and 4.3 V after 100 cycles. The results indicate that the CeO2 surface treatment should be an effective way to improve cycle properties due to CeO2 inhibit the electrodes and the electrolyte side effects.

Synthesis of FeCoNi nanoparticles by galvanostatic technique

International Nuclear Information System (INIS)

Budi, Setia; Hafizah, Masayu Elita; Manaf, Azwar

2016-01-01

Soft magnetic nanoparticles of FeCoNi have been becoming interesting objects for many researchers due to its potential application in electronic devices. One of the most promising methods for material preparation is the electrodeposition which capable of growing nanoparticles alloy directly onto the substrate. In this paper, we report our electrodeposition studies on nanoparticles synthesis using galvanostatic electrodeposition technique. Chemical composition of the synthesized FeCoNi was successfully controlled through the adjustment of the applied currents. It is revealed that the content of each element, obtained from quantitative analysis using atomic absorption spectrometer (AAS), could be modified by the adjustment of current in which Fe and Co content decreased at larger applied currents, while Ni content increased. The nanoparticles of Co-rich FeCoNi and Ni-rich FeCoNi were obtained from sulphate electrolyte at the range of applied current investigated in this work. Broad diffracted peaks in the X-ray diffractograms indicated typical nanostructures of the solid solution of FeCoNi.

Synthesis of FeCoNi nanoparticles by galvanostatic technique

Energy Technology Data Exchange (ETDEWEB)

Budi, Setia, E-mail: setiabudi@unj.ac.id [Potgraduate Program of Materials Science Study, Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, Depok 16424 (Indonesia); Department of Chemistry, Faculty of Mathematics and Sciences, Universitas Negeri Jakarta, Jl. Pemuda No.10, Rawamangun, Jakarta 13220 (Indonesia); Hafizah, Masayu Elita; Manaf, Azwar, E-mail: azwar@ui.ac.id [Potgraduate Program of Materials Science Study, Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, Depok 16424 (Indonesia)

2016-06-17

Soft magnetic nanoparticles of FeCoNi have been becoming interesting objects for many researchers due to its potential application in electronic devices. One of the most promising methods for material preparation is the electrodeposition which capable of growing nanoparticles alloy directly onto the substrate. In this paper, we report our electrodeposition studies on nanoparticles synthesis using galvanostatic electrodeposition technique. Chemical composition of the synthesized FeCoNi was successfully controlled through the adjustment of the applied currents. It is revealed that the content of each element, obtained from quantitative analysis using atomic absorption spectrometer (AAS), could be modified by the adjustment of current in which Fe and Co content decreased at larger applied currents, while Ni content increased. The nanoparticles of Co-rich FeCoNi and Ni-rich FeCoNi were obtained from sulphate electrolyte at the range of applied current investigated in this work. Broad diffracted peaks in the X-ray diffractograms indicated typical nanostructures of the solid solution of FeCoNi.

Hierarchical porous NiCo2O4 nanowires for high-rate supercapacitors.

Science.gov (United States)

Jiang, Hao; Ma, Jan; Li, Chunzhong

2012-05-11

We demonstrate a simple and scalable strategy for synthesizing hierarchical porous NiCo(2)O(4) nanowires which exhibit a high specific capacitance of 743 F g(-1) at 1 A g(-1) with excellent rate performance (78.6% capacity retention at 40 A g(-1)) and cycling stability (only 6.2% loss after 3000 cycles). This journal is © The Royal Society of Chemistry 2012

Preparation of layered oxide Li(Co1/3Ni1/3Mn1/3)O2 via the sol-gel process

Institute of Scientific and Technical Information of China (English)

ZHANG Wen; LIU Hanxing; HU Chen; ZHU Xianjun; LI Yanxi

2008-01-01

To obtain homogenous layered oxide Li(Co1/3Ni1/3Ni1/3Mn1/3)O2 as a lithium insertion positive electrode material,the sol-gel process using citric acid as a chelating agent was applied.The material Li(Co1/3,Ni1/3Mn1/3)O2 was synthesized at different calcination temperatures.XRD experiment indicated that the hyered Li(Co1/3Ni1/3Mn1/3)O2material could he synthesized at a lower temperature of 800℃,and the oxidation state of Co,Ni,and Mn in the cathode confirmed by XPS were +3,+2,and +4,respectively.SEM observations showed that the synthesized material could form homogenous particle morphology with the particle size of about 200nm In spite of different calcination temperatures,the charge-discharge curves of all the samples for the initial cycle were similar,and the cathode synthesized at 900℃ showed a small irreversible capacity loss of 11.24% and a high discharge capacity of 212.2 mAh.g-1 in the voltage range of 2.9-4.6 V.

Electrochemical preparation and characteristics of Ni-Co-LaNi5 composite coatings as electrode materials for hydrogen evolution

International Nuclear Information System (INIS)

Wu Gang; Li Ning; Dai Changsong; Zhou Derui

2004-01-01

Electrocatalytic activity for the hydrogen evolution reaction on Ni-Co-LaNi 5 composite electrodes prepared by electrochemical codeposition technique was evaluated. The relationship between the current density for hydrogen evolution reaction and the amount of LaNi 5 particles in Ni-Co baths is like the well-known 'volcano plot'. The Surface morphology and microstructure of Ni-Co-LaNi 5 coatings were determined by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). The kinetic parameters were determined from electrochemical steady-state Tafel polarization and electrochemical impedance spectroscopy technology in 1 M NaOH solution. The values obtained for the apparent energies of activation are 32.48, 46.29 and 57.03 kJ mol -1 for the Ni-Co-LaNi 5 , Ni-Co and Ni electrodes, respectively. The hydrogen evolution reaction on Ni-Co-LaNi 5 proceeds via Volmer-Tafel reaction route with the mixed rate determining characteristics. The composite coating Ni-Co-LaNi 5 is catalytically more active than Ni and Ni-Co electrodes due to the increase in its real surface areas and the decrease in the apparent free energy of activation caused by the electrocatalytic synergistic effect of the Ni-Co alloys and the hydrogen storage intermetallic particles on the electrode surface

Study of promotion of CO2 fixation by the environmental improvement in the coral reef area; Kansho chitai ni okeru kankyo kaizen ni yoru CO2 kotei sokushin no kenkyu

Energy Technology Data Exchange (ETDEWEB)

Maruoka, T.; Ishitani, H.; Matsuhashi, R.; Yamada, K.; Komiyama, H.; Kraines, S. [The University of Tokyo, Tokyo (Japan). Faculty of Engineering

1997-01-30

A study was conducted on how to fix CO2 in the ocean using coral reefs. Coral reefs have extremely high primary productivity ( production quantity of organic matters by photosynthesis) and are expected to be resources to fix CO2 when the quantity of photosynthesis exceeds the quantity of CO2 emitted in association with formation of calcium carbonate skeleton. If organic substances produced in coral reefs are well carried into the open sea, those are settled down on deep beds, which enables the storage into the ocean. At the coral reef floating in the ocean, it is not very deep inside and the seawater stays there, but it has a steep depth outside. By the numerical calculation, an examination was made on how the waterflow changes when making the flow path of seawater between the inland sea and open sea. From the actual calculation of an atoll, it was found that seawater comes in and out from the open sea to the inland sea near the opening of the atoll in accordance with the high tide and ebb tide, but the water stays at the deep bottom of the atoll. When installing a channel with a 10m depth at the portion where the water flows softly, the seawater was actively exchanged. 6 refs., 4 figs.

CeNi{sub 3}-type rare earth compounds: crystal structure of R{sub 3}Co{sub 7}Al{sub 2} (R=Y, Gd–Tm) and magnetic properties of {Gd–Er}{sub 3}Co{sub 7}Al{sub 2}, {Tb, Dy}{sub 3}Ni{sub 8}Si and Dy{sub 3}Co{sub 7.68}Si{sub 1.32}

Energy Technology Data Exchange (ETDEWEB)

Morozkin, A.V., E-mail: morozkin@tech.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-1, Moscow 119991 (Russian Federation); Yapaskurt, V.O. [Department of Petrology, Geological Faculty Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Nirmala, R. [Indian Institute of Technology Madras, Chennai 600 036 (India); Quezado, S.; Malik, S.K. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59082-970 (Brazil)

2017-03-15

The crystal structure of new CeNi{sub 3}-type {Y, Gd–Tm}{sub 3}Co{sub 7}Al{sub 2} (P63/mmc. N 194, hP24) compounds has been established using powder X-ray diffraction studies. The magnetism of Tb{sub 3}Ni{sub 8}Si and Dy{sub 3}Ni{sub 8}Si is dominated by rare earth sublattice and the magnetic properties of R{sub 3}Co{sub 7}Al{sub 2} (R =Gd–Er) and Dy{sub 3}Co{sub 7.68}Si{sub 1.32} are determined by both rare earth and cobalt sublattices. Magnetization data indicate ferromagnetic ordering of {Tb, Dy}{sub 3}Ni{sub 8}Si at 32 K and 21 K, respectively. Gd{sub 3}Co{sub 7}Al{sub 2} and Tb{sub 3}Co{sub 7}Al{sub 2} exhibit ferromagnetic ordering at 309 K and 209 K, respectively, whereas Dy{sub 3}Co{sub 7}Al{sub 2}, Ho{sub 3}Co{sub 7}Al{sub 2}, Er{sub 3}Co{sub 7}Al{sub 2} and Dy{sub 3}Co{sub 7.68}Si{sub 1.32} show a field dependent ferromagnetic-like ordering at 166 K, 124 K, 84 K and 226 K, respectively followed by a low temperature transition at 34 K for Dy{sub 3}Co{sub 7}Al{sub 2}, 18 K for Ho{sub 3}Co{sub 7}Al{sub 2}, 56 K for Er{sub 3}Co{sub 7}Al{sub 2}, 155 K and 42 K for Dy{sub 3}Co{sub 7.68}Si{sub 1.32}. Among these compounds, Dy{sub 3}Ni{sub 8}Si shows largest magnetocaloric effect (isothermal magnetic entropy change) of −11.6 J/kg·K at 18 K in field change of 50 kOe, whereas Tb{sub 3}Co{sub 7}Al{sub 2}, Dy{sub 3}Co{sub 7}Al{sub 2} and Dy{sub 3}Co{sub 7.68}Si{sub 1.32} exhibit best permanent magnet properties in the temperature range of 2–5 K with remanent magnetization of 11.95 μ{sub B}/fu, 12.86 μ{sub B}/fu and 14.4 μ{sub B}/fu, respectively and coercive field of 3.0 kOe, 1.9 kOe and 4.4 kOe, respectively. - Highlights: • {Y, Gd–Tm}{sub 3}Co{sub 7}Al{sub 2} compounds crystallize in the CeNi{sub 3}-type structure. • {Gd-Er}{sub 3}Co{sub 7}Al{sub 2} show ferrimagnetic ordering at 309 K, 209 K, 166 K, 124 K and 84 K. • Dy{sub 3}Co{sub 7.68}Si{sub 1.32} exhibits magnetic transitions at 226 K, 155 K and 42 K. • {Tb-Er}{sub 3}Co{sub 7}Al{sub 2

Mesoporous NiCo2O4 nanoneedles grown on 3D graphene-nickel foam for supercapacitor and methanol electro-oxidation

International Nuclear Information System (INIS)

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

2015-01-01

Mesoporous NiCo 2 O 4 nanoneedles were directly grown on three dimensional (3D) graphene-nickel foam which was prepared by chemical vapor deposition, labeled as NCO/GNF. The structure and morphology of NCO/GNF were investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, element mapping and Raman spectroscopy. The NCO/GNF was employed as electrodes for supercapacitor and methanol electro-oxidation. When used for supercapacitor, the NiCo 2 O 4 nanoneedles exhibit hi exhibit high specific capacitance (1588 F g −1 at 1 A g −1 ), high power density and energy density (33.88 Wh kg −1 at 5 kW kg −1 ) as well as long cycling stability. In methanol electro-oxidation, the NiCo 2 O 4 nanoneedles deliver high electro-oxidation activity (93.3 A g −1 at 0.65 V) and electro-oxidation stability. The good electrochemical performance of NiCo 2 O 4 nanoneedles is attributed to the 3D structure with large specific area, high conductivity and fast ions/electrons transport

Ionic liquid-assisted electrochemical determination of pyrimethanil using reduced graphene oxide conjugated to flower-like NiCo{sub 2}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Yang, Lijun; Hu, Yandong; Wang, Qiong; Dong, Yuanyuan; Zhang, Lei, E-mail: zhanglei63@126.com

2016-09-07

The novel hierarchical flower-like superstructure NiCo{sub 2}O{sub 4}/reduced graphene oxide (rGO) hybrids have been successfully synthesized with a facile one-step hydrothermal process for the determination of fungicide pyrimethanil (PMT). For comparison, various structures of NiCo{sub 2}O{sub 4}/rGO including hexagonal nanoplates and nanorods were also synthesized. Among them, three-dimensional (3D) flower-like NiCo{sub 2}O{sub 4}/rGO exhibited the highest electrocatalytic activity for the oxidation of PMT. With the synergistic effect of [OMIM]PF{sub 6} ionic liquid (IL), the electrochemical sensor film (NiCo{sub 2}O{sub 4}/rGO/IL) further facilitated interfacial electron transfer and enhanced electrocatalytic activity for the oxidation of PMT. Under the optimum conditions, the electrochemical sensor exhibited two linear ranges of 0.1–10.0 μmol/L and 20.0–140 μmol/L for PMT with a low detection concentration of 11.0 nmol/L. Besides, the interference, repeatability, reproducibility and stability measurements were also evaluated. The proposed method was successfully applied to the detection of PMT in water, seawater, fruits and vegetables with good recovery ranging from 93% to 105%, and possessed potential applications in the analysis of real samples. - Highlights: • A novel sensor based on layered flower-like NiCo{sub 2}O{sub 4}/rGO/IL hybrid was fabricated. • Various structures of NiCo{sub 2}O{sub 4}/rGO were synthesized for electrocatalytic comparison. • 3D structure NiCo{sub 2}O{sub 4}/rGO/IL/GCE displayed superior electrocatalytic activity for PMT. • The sensor showed a much wider linear range and a lower detection limit than others. • The method was satisfactorily applied to detection of PMT in real samples.

Electrochemical performance of co-doped Li1.2Mn0.6Ni0.2O2 cathode materials

CSIR Research Space (South Africa)

David, K

2013-04-01

Full Text Available The composite material has a xLi2MnO3·(1-x)LiMO2 (M = Mn, Co, Ni) structure has been considered as one of the most promising cathode materials for advanced lithium-ion batteries due to their low-cost and high capacity (> 200 mAh g−1) between 4.8 V...

One-pot synthesis of hollow NiSe-CoSe nanoparticles with improved performance for hybrid supercapacitors

Science.gov (United States)

Chen, Haichao; Fan, Meiqiang; Li, Chao; Tian, Guanglei; Lv, Chunju; Chen, Da; Shu, Kangying; Jiang, Jianjun

2016-10-01

Hollow NiSe-CoSe samples have been synthesized for the first time via a one-pot solvothermal approach. The strategy is robust enough to synthesize NiSe-CoSe nanoparticles with different NiSe to CoSe ratios but with a similar hollow structure. Co ions in the NiSe-CoSe nanoparticles play decisive role for formation of the hollow structure; otherwise, the nanoparticles become solid for the NiSe sample. When used as the positive electroactive materials for energy storage, the NiSe-CoSe samples show excellent electrochemical activity in alkaline electrolyte. Using the synergistic effect between NiSe and CoSe, the electrochemical performance of NiSe-CoSe can be tuned by varying the NiSe to CoSe ratios. The NiSe-CoSe sample with a NiSe to CoSe ratio of 4:2 shows the best electrochemical performance in terms of superior specific capacity, improved rate capability and excellent cycling stability. In addition, the electrochemical performance of NiSe-CoSe sample with a NiSe to CoSe ratio of 4:2 is also evaluated via assembling hybrid supercapacitors with RGO, and the hybrid supercapacitor delivers both high power and energy densities (41.8 Wh kg-1 at 750 W kg-1 and 20.3 Wh kg-1 at 30 kW kg-1).

Magneto-plasmonic study of aligned Ni, Co and Ni/Co multilayer in polydimethylsiloxane as magnetic field sensor

Energy Technology Data Exchange (ETDEWEB)

Hamidi, Seyedeh Mehri, E-mail: M_hamidi@sbu.ac.ir [Magneto-plasmonic Lab, Laser and Plasma Research Institute, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Mosaeii, Babak; Afsharnia, Mina [Magneto-plasmonic Lab, Laser and Plasma Research Institute, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Aftabi, Ali [Physics Department, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Najafi, Mojgan [Department of Materials Engineering, Hamedan University of Technology, Hamedan (Iran, Islamic Republic of)

2016-11-01

We report the magneto-optical properties of aligned cobalt, Nickel and nickel/ Cobalt multilayer nanowires embedded in polydimethylsiloxane matrix. The NWs prepared by electrodeposition method in anodic alumina template and then dispersed in ethanol and placed in a heater to evaporate the ethanol and finally dispersed in polydimethylsiloxane matrix to reach to the composite. The used external magnetic field arranges the nanowires and our aligned nanowires were investigated by magneto-optical surface plasmon resonance techniques in two easy and hard axis configurations. Our results show the sufficient sensitivity in magneto-optical surface plasmon resonance of Nickel and cobalt arrays nanowires and because the different modulation mechanism in Ni and Co nanodisks, in Ni/Co multilayer we see the magnetization modulation of the excitation angle in accordance with magnetic field modulation of the SPP wave vector in each nanodisk. Finally, we show that the Ni/Co multilayer aligned nanowires can be used as efficient magnetic field sensor. - Highlights: • The magneto-optical properties of aligned multilayer nanowires has been investigated. • We see the sufficient sensitivity in magneto-optical surface plasmon resonance of Ni and Co nanowires. • The magnetic modulation mechanism in Ni/Co multilayer has been changed by angular modulation. • The magnetization modulation of the excitation angle accompanying the SPP wave vector modulation takes place in each nanodisk of multilayer.

Construction of Hierarchical CuO/Cu2O@NiCo2S4 Nanowire Arrays on Copper Foam for High Performance Supercapacitor Electrodes

Science.gov (United States)

Zhou, Luoxiao; He, Ying; Jia, Congpu; Pavlinek, Vladimir; Saha, Petr; Cheng, Qilin

2017-01-01

Hierarchical copper oxide @ ternary nickel cobalt sulfide (CuO/Cu2O@NiCo2S4) core-shell nanowire arrays on Cu foam have been successfully constructed by a facile two-step strategy. Vertically aligned CuO/Cu2O nanowire arrays are firstly grown on Cu foam by one-step thermal oxidation of Cu foam, followed by electrodeposition of NiCo2S4 nanosheets on the surface of CuO/Cu2O nanowires to form the CuO/Cu2O@NiCo2S4 core-shell nanostructures. Structural and morphological characterizations indicate that the average thickness of the NiCo2S4 nanosheets is ~20 nm and the diameter of CuO/Cu2O core is ~50 nm. Electrochemical properties of the hierarchical composites as integrated binder-free electrodes for supercapacitor were evaluated by various electrochemical methods. The hierarchical composite electrodes could achieve ultrahigh specific capacitance of 3.186 F cm−2 at 10 mA cm−2, good rate capability (82.06% capacitance retention at the current density from 2 to 50 mA cm−2) and excellent cycling stability, with capacitance retention of 96.73% after 2000 cycles at 10 mA cm−2. These results demonstrate the significance of optimized design and fabrication of electrode materials with more sufficient electrolyte-electrode interface, robust structural integrity and fast ion/electron transfer. PMID:28914819

Construction of Hierarchical CuO/Cu2O@NiCo2S4 Nanowire Arrays on Copper Foam for High Performance Supercapacitor Electrodes

Directory of Open Access Journals (Sweden)

Luoxiao Zhou

2017-09-01

Full Text Available Hierarchical copper oxide @ ternary nickel cobalt sulfide (CuO/Cu2O@NiCo2S4 core-shell nanowire arrays on Cu foam have been successfully constructed by a facile two-step strategy. Vertically aligned CuO/Cu2O nanowire arrays are firstly grown on Cu foam by one-step thermal oxidation of Cu foam, followed by electrodeposition of NiCo2S4 nanosheets on the surface of CuO/Cu2O nanowires to form the CuO/Cu2O@NiCo2S4 core-shell nanostructures. Structural and morphological characterizations indicate that the average thickness of the NiCo2S4 nanosheets is ~20 nm and the diameter of CuO/Cu2O core is ~50 nm. Electrochemical properties of the hierarchical composites as integrated binder-free electrodes for supercapacitor were evaluated by various electrochemical methods. The hierarchical composite electrodes could achieve ultrahigh specific capacitance of 3.186 F cm−2 at 10 mA cm−2, good rate capability (82.06% capacitance retention at the current density from 2 to 50 mA cm−2 and excellent cycling stability, with capacitance retention of 96.73% after 2000 cycles at 10 mA cm−2. These results demonstrate the significance of optimized design and fabrication of electrode materials with more sufficient electrolyte-electrode interface, robust structural integrity and fast ion/electron transfer.

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

Photonic, and photocatalytic behavior of TiO{sub 2} mediated by Fe, CO, Ni, N doping and co-doping

Energy Technology Data Exchange (ETDEWEB)

Wang, Jia [College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan (China); Zhao, Y.F. [Institute of Coordination Bond Metrology and Engineering, School of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Wang, T., E-mail: twang@zju.edu.cn [College of Electrical Engineering, Zhejiang University (China); Li, H., E-mail: Lihui02@tyut.edu.cn [College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan (China); Li, C., E-mail: canli1983@gmail.com [Institute of Coordination Bond Metrology and Engineering, School of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China)

2015-12-01

Fe, Co, Ni, or N addition could modulate the photonic and catalytic responses of TiO{sub 2} for photocatalysts applications. Their morphologies, structures, compositions and photocatalytic performance in the degradation of methylene blue were characterized by scanning electron microscopy, X-ray diffraction, UV–vis absorption spectroscopy, Raman spectra and X-ray photoelectron spectroscopy. The results showed that dopants affect the electronic transition energies by changing the optical band gap and the impurity absorption peaks of the specimens. Especially, co-doping enhances the visible-light photocatalytic activity of TiO{sub 2} by 4–10 times that of pure TiO{sub 2}, and the Co and N co-doping derives 10-fold photocatalytic activity.

A facile and scalable strategy for synthesis of size-tunable NiCo2O4 with nanocoral-like architecture for high-performance supercapacitors

International Nuclear Information System (INIS)

Tao, Yan; Ruiyi, Li; Zaijun, Li; Yinjun, Fang

2014-01-01

Graphical abstract: We reported a facile and scalable strategy for synthesis of size-tunable NiCo 2 O 4 with nanocoral-like architecture. The unique structure will improve faradaic redox reaction and mass transfer, NiCo 2 O 4 offers excellent electrochemical performance for supercapacitors. - Highlights: • We reported a facile and scalable strategy for synthesis of size-tunable NiCo 2 O 4 withnanocoral-lide architecture. • Combination of microwave and tertbutanol as medium creates ultrathin nickel/cobalt double hydroxide with flowerclusters. • The method is very simple, rapid and efficient, it can be used for large scale productionof nanomaterials. • The size of NiCo 2 O 4 nanocorals is easy to be can be controlled by adjusting calcination temperature. • Unique structure enhances rates of electron transfer and mass transport, NiCo 2 O 4 shows high electrochemical performance. - Abstract: There is a great need to develop high-performance electroactive materials for supercapacitors. The study reported a facile and scalable strategy for synthesis of size-tunable NiCo 2 O 4 with nanocoral-like architecture. Cobalt nitrate and nickel nitrate were dissolved in a tertbutanol solution and heated to reflux state under microwave radiation. The amounts of ammonia was dropped into the mixed solution to form nickel/cobalt double hydroxides. The reaction can complete within 15 min with the productivity of 99.9%. The obtained double hydroxides display flowercluster-like ultrathin nanostructure. The double hydroxide was calcined into different NiCo 2 O 4 products using different calcination temperature, including 400 °C, 500 °C, 600 °C and 700 °C. The resulting NiCo 2 O 4 is of nanocoral-like architecture. Interestingly, the size of coral can be easily controlled by adjusting the temperature. The NiCo 2 O 4 prepared at 400°C gives a minimum building block size (10.2 nm) and maximum specific surface area (108.8 m 2 ·g −1 ). The unique structure will greatly

Magnetic order and crystal fields in the Pnma phases of Tm2BaTO5(T=Co and Ni)

International Nuclear Information System (INIS)

Harker, S.J.; Stewart, G.A.

2000-01-01

The magnetic ordering and crystal field interactions of the Pnma phases of both Tm 2 BaCoO 5 and Tm 2 BaNiO 5 are investigated by 169 Tm Moessbauer spectroscopy and the temperature-dependent hyperfine interactions are compared with those obtained elsewhere for Tm 2 BaCuO 5 . The Pnma phases are shown to order magnetically at temperatures of 3.5(2) K (Tm 2 BaCoO 5 ) and 4.85(5) K (Tm 2 BaNiO 5 ), the order being induced by the transition metal. For Tm 2 BaNiO 5 an additional first-order transition observed at T≤1.4 K is identified with the independent magnetic order of the thulium sub-lattice. (orig.)

NiMn layered double hydroxide nanosheets/NiCo2O4 nanowires with surface rich high valence state metal oxide as an efficient electrocatalyst for oxygen evolution reaction

Science.gov (United States)

Yang, Liting; Chen, Lin; Yang, Dawen; Yu, Xu; Xue, Huaiguo; Feng, Ligang

2018-07-01

High valence transition metal oxide is significant for anode catalyst of proton membrane water electrolysis technique. Herein, we demonstrate NiMn layered double hydroxide nanosheets/NiCo2O4 nanowires hierarchical nanocomposite catalyst with surface rich high valence metal oxide as an efficient catalyst for oxygen evolution reaction. A low overpotential of 310 mV is needed to drive a 10 mA cm-2 with a Tafel slope of 99 mV dec-1, and a remarkable stability during 8 h is demonstrated in a chronoamperometry test. Theoretical calculation displays the change in the rate-determining step on the nanocomposite electrode in comparison to NiCo2O4 nanowires alone. It is found high valence Ni and Mn oxide in the catalyst system can efficiently facilitate the charge transport across the electrode/electrolyte interface. The enhanced electrical conductivity, more accessible active sites and synergistic effects between NiMn layered double hydroxide nanosheets and NiCo2O4 nanowires can account for the excellent oxygen evolution reaction. The catalytic performance is comparable to most of the best non-noble catalysts and IrO2 noble catalyst, indicating the promising applications in water-splitting technology. It is an important step in the development of hierarchical nanocomposites by surface valence state tuning as an alternative to noble metals for oxygen evolution reaction.

Beta decay of 72Co and excited levels in 72Ni

International Nuclear Information System (INIS)

Grzywacz, R.; Rykaczewski, K.; Sawicka, M.; Pfuetzner, M.; Daugas, J.M.; Belier, G.; Sauvestre, J.E.; Meot, V.; Roig, O.; Giovinazzo, J.; Grawe, H.; Mayet, P.; Matea, I.; Georgiev, G.; Lewitowicz, M.; Olivieira, F. de; Stodel, C.; Saint-Laurent, M. G.; Stanoiu, M.; Verney, D.

2003-01-01

An experiment was performed at GANIL to observe isomeric- and beta-delayed gamma rays from very neutron-rich nuclei around 74Ni. Fragmentation products of the 86Kr beam at 58 AMeV were studied using new devices: the LISE 2000 spectrometer and detectors from the EXOGAM germanium array. The primary aim of the experiment was to find the 8+ microsecond isomer in 76Ni and to perform beta decay spectroscopy of Co nuclei. We have successfully measured the beta delayed gammas from the decay of 72Co to 72Ni. The energies for the lowest excited states in 72Ni are proposed, with the first 2+ state at 1096 keV. These findings suggest a solution of the problem of the disappearance of the 8+ isomer in 72Ni. We also measured beta decay of other neutron-rich Co isotopes including 70Co. First evidence was found for a new short lived isomer, most likely the Iπ=8+ state, in 76Ni

Hot corrosion of Co-Cr, Co-Cr-Al, and Ni-Cr alloys in the temperature range of 700-750 deg C

Science.gov (United States)

Chiang, K. T.; Meier, G. H.

1980-01-01

The effect of SO3 pressure in the gas phase on the Na2SO4 induced hot corrosion of Co-Cr, Ni-Cr, and Co-Cr-Al alloys was studied in the temperature range 700 to 750 C. The degradation of the Co-Cr and Ni-Cr alloys was found to be associated with the formation of liquid mixed sulfates (CoSO4-Na2SO4 or NiSO4-Na2SO4) which provided a selective dissolution of the Co or Ni and a subsequent sulfidation oxidation mode of attack which prevented the maintenance of a protective Cr2O3 film. A clear mechanism was not developed for the degradation of Co-Cr-Al alloys. A pitting corrosion morphology was induced by a number of different mechanisms.

Magnetic and dielectric properties of the ruthenium double perovskites La2MRuO6 (M=Mg, Co, Ni, and Zn)

International Nuclear Information System (INIS)

Yoshii, Kenji; Ikeda, Naoshi; Mizumaki, Masaichiro

2006-01-01

Magnetic and dielectric properties of the ruthenium double perovskites La 2 MRuO 6 (M=Mg, Co, Ni, and Zn) were investigated. The magnetization measurements for M=Co and Ni showed the existence of magnetic order at 20-30 K. Though the oxides with M=Zn and Mg exhibit a deviation from the Curie-Weiss law, magnetic order was not clearly observed. The result of La 2 ZnRuO 6 was different from that previously reported, in which a ferromagnetic transition was found at around 165 K. The AC dielectric measurements for M = Co and Ni showed large dielectric constants (typically larger than 1000) at around room temperature, suggesting both the formation of short-ranged polar regions and the magnetic origin of large dielectric constant. In addition, two peaks were found for the temperature dependence of the tan δ component for La 2 NiRuO 6 . The behavior suggests the existence of two different polar regions. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (Abstract Copyright [2006], Wiley Periodicals, Inc.)

Influence of the Cr and Ni concentration in CoCr and CoNi alloys on the structural and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Aubry, E. [Nipson Technology, 12 Avenue des Trois chênes, Techn’Hom 3, Belfort 90000 (France); Liu, T. [Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine, Vandoeuvre-lès-Nancy 54506 (France); Billard, A. [IRTES-LERMPS EA 7274, UTBM, Site de Montbéliard, Belfort Cedex 90010 (France); Dekens, A. [Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine, Vandoeuvre-lès-Nancy 54506 (France); Perry, F. [PVDco, 30 rue de Badménil, Baccarat 54120 (France); Mangin, S.; Hauet, T. [Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine, Vandoeuvre-lès-Nancy 54506 (France)

2017-01-15

The crystalline and magnetic properties of micron thick magnetron sputtered Co{sub 1−x}Cr{sub x} and Co{sub 1−x}Ni{sub x} alloy films are analyzed in the view of their implementation as semi-hard magnets. All of the tested films crystallize in an hcp lattice, at least up to 35 at% of alloying elements (Cr or Ni). The structural study shows that the ratio of hcp phase with [0001] axis orientated perpendicular to the film as compared with in-plane orientation increases (resp. decreases), when Ni (resp. Cr) concentration increases independently of the post-annealing temperature. The orientation of the magnetization results from the competition between the demagnetization field which tends to align the magnetization in plane and the crystalline anisotropy which tends to maintain the magnetization along the [0001] axis. Interestingly, we find that, although Co and Ni are very similar atoms, Co{sub 1−x}Ni{sub x} alloys crystalline anisotropy can be strongly increased and reach up to twice the anisotropy of the best Co{sub 1−x}Cr{sub x} alloy, while maintaining a magnetization at saturation above 1200 kA/m. The thermal stability of the structural and magnetic properties of both alloys is demonstrated for an annealing temperature up to 300 °C. - Highlights: • Sputtered CoCr and CoNi films are analyzed for their semi-hard magnetic properties. • CoNi alloys exhibits higher saturation magnetization and crystalline anisotropy. • These evolutions can be directly correlated to the quality of hcp crystal orientation. • Thermal stability of structural and magnetic properties is demonstrated up to 300 °C.

Effect of separated layer thickness on magnetoresistance and magnetic properties of Co/Dy/Co and Ni/Dy/Ni film systems

Science.gov (United States)

Shabelnyk, T. M.; Shutylieva, O. V.; Vorobiov, S. I.; Pazukha, I. M.; Chornous, A. M.

2018-01-01

Co(5 nm)/Dy(tDy)/Co(20 nm)/S and Ni(5 nm)/Dy(tDy)/Ni(20 nm)/S trilayer films are prepared by electron-beam sputtering to investigate the influence of dysprosium layer thickness (tDy) and thermal annealing on the crystal structure, magnetoresistance (MR) and magnetic properties of thin films. The thickness of Dy layer changed in the range from 1 nm to 20 nm. The samples annealed for 20 min at 700 K. Electron diffraction patterns reveal that the as-deposited and annealed systems Co/Dy/Co and Ni/Dy/Ni had fcc-Co + hcp-Dy and fcc-Ni + hcp-Dy phase state, respectively. It is also shown that at the tDy = 15 nm the transition from amorphous to crystalline structures of Dy layer is observed. An increase in the Dy layer thickness results in changes in the MR and magnetic properties of the trilayer systems. It is shown that MR is most thermally stable against annealing to 700 K at tDy = 15 nm for Co/Dy/Co as well as for Ni/Dy/Ni. For tDy = 15 nm the, value of MR for both system increases by two times compared to those of pure ferromagnetic (FM) samples. The coercivity (Bc), remanent (Mr) and saturation (Ms) magnetization of the in-plain magnetization hysteresis loops are related to the Dy layer thickness too. The coercivity depends on the FM materials type and diffusion processes at the layer boundary. Accordingly, Mr and Ms are reduced with tDy increasing before and after annealing for both trilayer systems.