Enhanced photocatalytic, electrochemical and photoelectrochemical properties of TiO2 nanotubes arrays modified with Cu, AgCu and Bi nanoparticles obtained via radiolytic reduction

International Nuclear Information System (INIS)

Nischk, Michał; Mazierski, Paweł; Wei, Zhishun; Siuzdak, Katarzyna; Kouame, Natalie Amoin; Kowalska, Ewa; Remita, Hynd; Zaleska-Medynska, Adriana

2016-01-01

Highlights: • TiO 2 nanotubes were modified with Cu, AgCu, Bi nanoparticles via gamma radiolysis. • Excessive amount of deposited metal decreased photocatalytic activity. • AgCu-modified samples were more active than Cu-modified (with the same Cu content). • AgCu nanoparticles exist in a core (Ag) -shell (Cu) form. • Examined photocatalysts were resistant towards photocorrosion processes. - Abstract: TiO 2 nanotubes arrays (NTs), obtained via electrochemical anodization of Ti foil, were modified with monometallic (Cu, Bi) and bimetallic (AgCu) nanoparticles. Different amounts of metals’ precursors were deposited on the surface of NTs by the spin-coating technique, and the reduction of metals was performed via gamma radiolysis. Surface modification of titania was studied by EDS and XPS analysis. The results show that AgCu nanoparticles exist in a Ag core -Cu shell form. Photocatalytic activity was examined under UV irradiation and phenol was used as a model pollutant of water. Over 95% of phenol degradation was achieved after 60 min of irradiation for almost all examined samples, but only slight difference in degradation efficiency (about 3%) between modified and bare NTs was observed. However, the initial phenol degradation rate and TOC removal efficiency was significantly enhanced for the samples modified with 0.31 and 0.63 mol% of Bi as well as for all the samples modified with Cu and AgCu nanoparticles in comparison with bare titania nanotubes. The saturated photocurrent, under the influence of simulated solar light irradiation, for the most active Bi- and AgCu-modified samples, was over two times higher than for pristine NTs. All the examined materials were resistant towards photocorrosion processes that enables their application for long term processes induced by light.

Enhanced photocatalytic, electrochemical and photoelectrochemical properties of TiO{sub 2} nanotubes arrays modified with Cu, AgCu and Bi nanoparticles obtained via radiolytic reduction

Energy Technology Data Exchange (ETDEWEB)

Nischk, Michał [Department of Chemical Technology, Faculty of Chemistry, Gdansk University of Technology, 11/12 G. Narutowicza 11/12 St., 80-233 Gdansk (Poland); Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, 63 Wita Stwosza St., 80-308 Gdansk (Poland); Mazierski, Paweł [Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, 63 Wita Stwosza St., 80-308 Gdansk (Poland); Wei, Zhishun [Institute for Catalysis, Hokkaido University, N21, W10, 001-0021, Sapporo (Japan); Siuzdak, Katarzyna [Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, 14 Fiszera St., 80-231 Gdansk (Poland); Kouame, Natalie Amoin [Laboratoire de Chimie Physique, CNRS—UMR 8000,Université Paris-Sud, Université Paris-Saclay, Bâtiment 349, 91405 Orsay (France); Kowalska, Ewa [Institute for Catalysis, Hokkaido University, N21, W10, 001-0021, Sapporo (Japan); Remita, Hynd [Laboratoire de Chimie Physique, CNRS—UMR 8000,Université Paris-Sud, Université Paris-Saclay, Bâtiment 349, 91405 Orsay (France); Zaleska-Medynska, Adriana, E-mail: adriana.zaleska@ug.edu.pl [Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, 63 Wita Stwosza St., 80-308 Gdansk (Poland)

2016-11-30

Highlights: • TiO{sub 2} nanotubes were modified with Cu, AgCu, Bi nanoparticles via gamma radiolysis. • Excessive amount of deposited metal decreased photocatalytic activity. • AgCu-modified samples were more active than Cu-modified (with the same Cu content). • AgCu nanoparticles exist in a core{sub (Ag)}-shell{sub (Cu)} form. • Examined photocatalysts were resistant towards photocorrosion processes. - Abstract: TiO{sub 2} nanotubes arrays (NTs), obtained via electrochemical anodization of Ti foil, were modified with monometallic (Cu, Bi) and bimetallic (AgCu) nanoparticles. Different amounts of metals’ precursors were deposited on the surface of NTs by the spin-coating technique, and the reduction of metals was performed via gamma radiolysis. Surface modification of titania was studied by EDS and XPS analysis. The results show that AgCu nanoparticles exist in a Ag{sub core}-Cu{sub shell} form. Photocatalytic activity was examined under UV irradiation and phenol was used as a model pollutant of water. Over 95% of phenol degradation was achieved after 60 min of irradiation for almost all examined samples, but only slight difference in degradation efficiency (about 3%) between modified and bare NTs was observed. However, the initial phenol degradation rate and TOC removal efficiency was significantly enhanced for the samples modified with 0.31 and 0.63 mol% of Bi as well as for all the samples modified with Cu and AgCu nanoparticles in comparison with bare titania nanotubes. The saturated photocurrent, under the influence of simulated solar light irradiation, for the most active Bi- and AgCu-modified samples, was over two times higher than for pristine NTs. All the examined materials were resistant towards photocorrosion processes that enables their application for long term processes induced by light.

Visible light photoelectrocatalysis with salicylic acid-modified TiO2 nanotube array electrode for p-nitrophenol degradation

International Nuclear Information System (INIS)

Wang Xin; Zhao Huimin; Quan Xie; Zhao Yazhi; Chen Shuo

2009-01-01

This research focused on immersion method synthesis of visible light active salicylic acid (SA)-modified TiO 2 nanotube array electrode and its photoelectrocatalytic (PEC) activity. The SA-modified TiO 2 nanotube array electrode was synthesized by immersing in SA solution with an anodized TiO 2 nanotube array electrode. Scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), UV-vis diffuse reflectance spectrum (DRS), and Surface photovoltage (SPV) were used to characterize this electrode. It was found that SA-modified TiO 2 nanotube array electrode absorbed well into visible region and exhibited enhanced visible light PEC activity on the degradation of p-nitrophenol (PNP). The degradation efficiencies increased from 63 to 100% under UV light, and 79-100% under visible light (λ > 400 nm), compared with TiO 2 nanotube array electrode. The enhanced PEC activity of SA-modified TiO 2 nanotube array electrode was attributed to the amount of surface hydroxyl groups introduced by SA-modification and the extension of absorption wavelength range.

Electrochemical preparation of vertically aligned, hollow CdSe nanotubes and their p-n junction hybrids with electrodeposited Cu2O.

Science.gov (United States)

Debgupta, Joyashish; Devarapalli, Ramireddy; Rahman, Shakeelur; Shelke, Manjusha V; Pillai, Vijayamohanan K

2014-08-07

Vertically aligned, hollow nanotubes of CdSe are grown on fluorine doped tin oxide (FTO) coated glass substrates by ZnO nanowire template-assisted electrodeposition technique, followed by selective removal of the ZnO core using NH4OH. A detailed mechanism of nucleation and anisotropic growth kinetics of nanotubes have been studied by a combination of characterization tools such as chronoamperometry, SEM and TEM. Interestingly, "as grown" CdSe nanotubes (CdSe NTs) on FTO coated glass plates behave as n-type semiconductors exhibiting an excellent photo-response (with a generated photocurrent density value of ∼ 470 μA cm(-2)) while in contact with p-type Cu2O (p-type semiconductor, grown separately on FTO plates) because of the formation of a n-p heterojunction (type II). The observed photoresponse is 3 times higher than that of a similar device prepared with electrodeposited CdSe films (not nanotubes) and Cu2O on FTO. This has been attributed to the hollow 1-D nature of CdSe NTs, which provides enhanced inner and outer surface areas for better absorption of light and also assists faster transport of photogenerated charge carriers.

Heterojunctions of mixed phase TiO2 nanotubes with Cu, CuPt, and Pt nanoparticles: interfacial band alignment and visible light photoelectrochemical activity

Science.gov (United States)

Kar, Piyush; Zhang, Yun; Mahdi, Najia; Thakur, Ujwal K.; Wiltshire, Benjamin D.; Kisslinger, Ryan; Shankar, Karthik

2018-01-01

Anodically formed, vertically oriented, self-organized cylindrical TiO2 nanotube arrays composed of the anatase phase undergo an interesting morphological and phase transition upon flame annealing to square-shaped nanotubes composed of both anatase and rutile phases. This is the first report on heterojunctions consisting of metal nanoparticles (NPs) deposited on square-shaped TiO2 nanotube arrays (STNAs) with mixed rutile and anatase phase content. A simple photochemical deposition process was used to form Cu, CuPt, and Pt NPs on the STNAs, and an enhancement in the visible light photoelectrochemical water splitting performance for the NP-decorated STNAs was observed over the bare STNAs. Under narrow band illumination by visible photons at 410 nm and 505 nm, Cu NP-decorated STNAs performed the best, producing photocurrents 80% higher and 50 times higher than bare STNAs, respectively. Probing the energy level structure at the NP-STNA interface using ultraviolet photoelectron spectroscopy revealed Schottky barrier formation in the NP-decorated STNAs, which assists in separating the photogenerated charge carriers, as also confirmed by longer charge carrier lifetimes in NP-decorated STNAs. While all the NP-decorated STNAs showed enhanced visible light absorption compared to the bare STNAs, only the Cu NPs exhibited a clear plasmonic behavior with an extinction cross section that peaked at 550 nm.

Design of flexible PANI-coated CuO-TiO2-SiO2 heterostructure nanofibers with high ammonia sensing response values

Science.gov (United States)

Pang, Zengyuan; Nie, Qingxin; Lv, Pengfei; Yu, Jian; Huang, Fenglin; Wei, Qufu

2017-06-01

We report a room-temperature ammonia sensor with extra high response values and ideal flexibility, including polyaniline (PANI)-coated titanium dioxide-silicon dioxide (TiO2-SiO2) or copper oxide-titanium dioxide-silicon dioxide (CuO-TiO2-SiO2) composite nanofibers. Such flexible inorganic TiO2-SiO2 and CuO-TiO2-SiO2 composite nanofibers were prepared by electrospinning, followed by calcination. Then, in situ polymerization of aniline monomers was carried out with inorganic TiO2-SiO2 and CuO-TiO2-SiO2 composite nanofibers as templates. Gas sensing tests at room temperature indicated that the obtained CuO-TiO2-SiO2/PANI composite nanofibers had much higher response values to ammonia gas (ca. 45.67-100 ppm) than most of those reported before as well as the prepared TiO2-SiO2/PANI composite nanofibers here. These excellent sensing properties may be due to the P-N, P-P heterojunctions and a structure similar to field-effect transistors formed on the interfaces between PANI, TiO2, and CuO, which is p-type, n-type, and p-type semiconductor, respectively. In addition, the prepared free-standing CuO-TiO2-SiO2/PANI composite nanofiber membrane was easy to handle and possessed ideal flexibility, which is promising for potential applications in wearable sensors in the future.

LCAO calculations of SrTiO3 nanotubes

International Nuclear Information System (INIS)

Evarestov, Robert; Bandura, Andrei

2011-01-01

The large-scale first-principles simulation of the structure and stability of SrTiO 3 nanotubes is performed for the first time using the periodic PBE0 LCAO method. The initial structures of the nanotubes have been obtained by the rolling up of the stoichiometric SrTiO 3 slabs consisting of two or four alternating (001) SrO and TiO 2 atomic planes. Nanotubes (NTs) with chiralities (n,0) and (n,n) have been studied. Two different NTs were constructed for each chirality: (I) with SrO outer shell, and (II) with TiO 2 outer shell. Positions of all atoms have been optimized to obtain the most stable NT structure . In the majority of considered cases the inner or outer TiO 2 shells of NT undergo a considerable reconstruction due to shrinkage or stretching of interatomic distances in the initial cubic perovskite structure. There were found two types of surface reconstruction: (1) breaking of Ti-O bonds with creating of Ti = O titanyl groups in outer surface; (2) inner surface folding due to Ti-O-Ti bending. Based on strain energy calculations the largest stability was found for (n,0) NTs with TiO 2 outer shell.

Synthesis of Fe2O3/TiO2 nanorod-nanotube arrays by filling TiO2 nanotubes with Fe

International Nuclear Information System (INIS)

Mohapatra, Susanta K; Banerjee, Subarna; Misra, Mano

2008-01-01

Synthesis of hematite (α-Fe 2 O 3 ) nanostructures on a titania (TiO 2 ) nanotubular template is carried out using a pulsed electrodeposition technique. The TiO 2 nanotubes are prepared by the sonoelectrochemical anodization method and are filled with iron (Fe) by pulsed electrodeposition. The Fe/TiO 2 composite is then annealed in an O 2 atmosphere to convert it to Fe 2 O 3 /TiO 2 nanorod-nanotube arrays. The length of the Fe 2 O 3 inside the TiO 2 nanotubes can be tuned from 50 to 550 nm by changing the deposition time. The composite material is characterized by scanning electron microscopy, transmission electron microscopy and diffuse reflectance ultraviolet-visible studies to confirm the formation of one-dimensional Fe 2 O 3 /TiO 2 nanorod-nanotube arrays. The present approach can be used for designing variable one-dimensional metal oxide heterostructures

Investigation on the influence of pH on structure and photoelectrochemical properties of CdSe electrolytically deposited into TiO2 nanotube arrays

International Nuclear Information System (INIS)

Xue, Jinbo; Shen, Qianqian; Yang, Fei; Liang, Wei; Liu, Xuguang

2014-01-01

Highlights: • There-dimensional CdSe-TiO 2 multijunction was fabricated by electrochemical method. • CdSe nanoparticles had a good bonding with the walls of TiO 2 nanotube. • pH value played an important role in the quality of CdSe-TiO 2 interfaces. - Abstract: In this work, we fabricated CdSe/TiO 2 nanotube arrays (NTAs) by electrochemical method. In electrodeposition, the pH value of the electrolyte played an important role in formation of CdSe nanoparticles. As the pH value decreased, more CdSe deposited on TiO 2 NTAs. Scanning electron microscopy and transmission electron microscopy characterization shows that the CdSe nanoparticles were uniformly deposited on and into TiO 2 nanotubes when the pH value was 3, and this structure fully utilized the three-dimensional (3D) space of TiO 2 nanotubes to form 3D multijunction heterostructures. According to the photoelectrochemical test, the CdSe/TiO 2 NTAs sample prepared at pH = 3 exhibited maximum photocurrent and open circuit potential. This is because that the deposited CdSe nanoparticles had better bond with the walls of TiO 2 nanotube than the samples deposited at other pH values, which facilitated the propagation and kinetic separation of photogenerated charges

Surface modification of TiO{sub 2} nanotubes with osteogenic growth peptide to enhance osteoblast differentiation

Energy Technology Data Exchange (ETDEWEB)

Lai, Min, E-mail: minlai@jsnu.edu.cn [School of Life Science, Jiangsu Normal University, Xuzhou, Jiangsu 221116 (China); Jin, Ziyang [School of Life Science, Jiangsu Normal University, Xuzhou, Jiangsu 221116 (China); Su, Zhiguo [Department of Pharmacy, The Affiliated hospital of Qingdao University, Qingdao, Shandong 266555 (China)

2017-04-01

To investigate the influence of surface-biofunctionalized substrates on osteoblast behavior, a layer of aligned TiO{sub 2} nanotubes with a diameter of around 70 nm was fabricated on titanium surface by anodization, and then osteogenic growth peptide (OGP) was conjugated onto TiO{sub 2} nanotubes through the intermediate layer of polydopamine. The morphology, composition and wettability of different surfaces were characterized by field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle measurements, respectively. The effects of OGP-modified TiO{sub 2} nanotube substrates on the morphology, proliferation and differentiation of osteoblasts were examined in vitro. Immunofluorescence staining revealed that the OGP-functionalized TiO{sub 2} nanotubes were favorable for cell spreading. However, there was no significant difference in cell proliferation observed among the different groups. Cells grown onto OGP-functionalized TiO{sub 2} nanotubes showed significantly higher (p < 0.05 or p < 0.01) levels of alkaline phosphatase (ALP) and mineralization after 4, 7 and 14 days of culture, respectively. Cells grown on OGP-functionalized TiO{sub 2} nanotubes had significantly higher (p < 0.05 or p < 0.01) expression of osteogenic-related genes including runt related transcription factor 2 (Runx2), ALP, collagen type I (Col I), osteopontin (OPN) and osteocalcin (OC) after 14 days of culture. These data suggest that surface functionalization of TiO{sub 2} nanotubes with OGP was beneficial for cell spreading and differentiation. This study provides a novel platform for the development and fabrication of titanium-based implants that enhance the propensity for osseointegration between the native tissue and implant interface. - Highlights: • The OGP functionalized TiO{sub 2} nanotube substrates were successfully fabricated through a direct and effective method. • The OGP functionalized substrates

LCAO calculations of SrTiO{sub 3} nanotubes

Energy Technology Data Exchange (ETDEWEB)

Evarestov, Robert; Bandura, Andrei, E-mail: re1973@re1973.spb.edu [Department of Quantum Chemistry, St. Petersburg State University, 26 Universitetsky Ave., 198504, Petrodvorets (Russian Federation)

2011-06-23

The large-scale first-principles simulation of the structure and stability of SrTiO{sub 3} nanotubes is performed for the first time using the periodic PBE0 LCAO method. The initial structures of the nanotubes have been obtained by the rolling up of the stoichiometric SrTiO{sub 3} slabs consisting of two or four alternating (001) SrO and TiO{sub 2} atomic planes. Nanotubes (NTs) with chiralities (n,0) and (n,n) have been studied. Two different NTs were constructed for each chirality: (I) with SrO outer shell, and (II) with TiO{sub 2} outer shell. Positions of all atoms have been optimized to obtain the most stable NT structure . In the majority of considered cases the inner or outer TiO{sub 2} shells of NT undergo a considerable reconstruction due to shrinkage or stretching of interatomic distances in the initial cubic perovskite structure. There were found two types of surface reconstruction: (1) breaking of Ti-O bonds with creating of Ti = O titanyl groups in outer surface; (2) inner surface folding due to Ti-O-Ti bending. Based on strain energy calculations the largest stability was found for (n,0) NTs with TiO{sub 2} outer shell.

Photocatalytic decouloration of malachite green dye by application of TiO2 nanotubes

International Nuclear Information System (INIS)

Prado, Alexandre G.S.; Costa, Leonardo L.

2009-01-01

The nanotubes of titania were synthesized in a hydrothermal system and characterized by scanning electronic microscopy (SEM), FT-IR, FT-Raman, and surface charge density by surface area analyzer. These nanomaterials were applied to photocatalyse malachite green dye degradation. Photodegradation capacity of TiO 2 nanotubes was compared to TiO 2 anatase photoactivity. Malachite dye was completely degraded in 75 and 105 min of reaction photocatalysed by TiO 2 nanotubes and TiO 2 anatase, respectively. Catalysts displayed high photodegradation activity at pH 4. TiO 2 nanotubes were easily recycled whereas the reuse of TiO 2 anatase was not effective. Nanotubes maintained 80% of their activity after 10 catalytic cycles and TiO 2 anatase presented only 8% of its activity after 10 cycles.

Incorporation of TiO2 nanotubes in a polycrystalline zirconia: Synthesis of nanotubes, surface characterization, and bond strength.

Science.gov (United States)

Dos Santos, Angélica Feltrin; Sandes de Lucena, Fernanda; Sanches Borges, Ana Flávia; Lisboa-Filho, Paulo Noronha; Furuse, Adilson Yoshio

2018-04-05

Despite numerous advantages such as high strength, the bond of yttria-stabilized zirconia polycrystal (Y-TZP) to tooth structure requires improvement. The purpose of this in vitro study was to evaluate the incorporation of TiO 2 nanotubes into zirconia surfaces and the bond strength of resin cement to the modified ceramic. TiO 2 nanotubes were produced by alkaline synthesis, mixed with isopropyl alcohol (50 wt%) and applied on presintered zirconia disks. The ceramics were sintered, and the surfaces were characterized by confocal laser microscopy, scanning electron microscopy (SEM), and energy-dispersive x-ray spectroscopy (EDS) analysis. For bond strength, the following 6 groups (n=16) were evaluated: without TiO 2 and Single Bond Universal; with TiO 2 nanotubes and Single Bond Universal; without TiO 2 nanotubes and Z-prime; with TiO 2 nanotubes and Z-prime; without TiO 2 and Signum Zirconia Bond; with TiO 2 and Signum Zirconia Bond. After sintering, resin cement cylinders, diameter of 1.40 mm and 1 mm in height, were prepared and polymerized for 20 seconds. Specimens were stored in water at 37°C for 30 days and submitted to a shear test. Data were analyzed by 2-way ANOVA and Tukey honest significant difference (α=.05) tests. EDS analysis confirmed that nanoagglomerates were composed of TiO 2 . The shear bond strength showed statistically significant differences among bonding agents (P<.001). No significant differences were found with the application of nanotubes, regardless of the group analyzed (P=.682). The interaction among the bonding agent factors and addition of nanotubes was significant (P=.025). Nanotubes can be incorporated into zirconia surfaces. However, this incorporation did not improve bond strength. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Thermal degradation of TiO2 nanotubes on titanium

Science.gov (United States)

Shivaram, Anish; Bose, Susmita; Bandyopadhyay, Amit

2014-10-01

The objective of this research was to study thermal degradation behavior of TiO2 nanotubes on titanium (Ti). TiO2 nanotubes were grown via anodization method on commercially pure Ti (Cp-Ti) discs using two different electrolytes, 1 vol. % HF in deionized (DI) water and 1 vol. % HF + 0.5 wt. % NH4F + 10 vol. % DI water in ethylene glycol, to obtain nanotubes with two different lengths, 300 nm and 950 nm keeping the nanotube diameter constant at 100 ± 20 nm. As grown TiO2 nanotubes were subjected to heat treatment to understand thermal degradation as a function of both temperature and hold time. The signs of degradation were observed mainly when amorphous nanotubes started to crystallize, however the crystallization temperature varied based on TiO2 nanotubes length and anodizing condition. Overall, 300 nm nanotubes were thermally stable at least up to 400 °C for 12 h, while the 950 nm long nanotubes show signs of degradation from 400 °C for 6 h only. Clearly, length of nanotubes, heat treatment temperature as well as hold times show influence toward degradation kinetics of TiO2 nanotubes on titanium.

Study of TiO2 nanotubes as an implant application

International Nuclear Information System (INIS)

Hazan, Roshasnorlyza; Sreekantan, Srimala; Mydin, Rabiatul Basria S. M. N.; Mat, Ishak; Abdullah, Yusof

2016-01-01

Vertically aligned TiO 2 nanotubes have become the primary candidates for implant materials that can provide direct control of cell behaviors. In this work, 65 nm inner diameters of TiO 2 nanotubes were successfully prepared by anodization method. The interaction of bone marrow stromal cells (BMSC) in term of cell adhesion and cell morphology on bare titanium and TiO 2 nanotubes is reported. Field emission scanning electron microscopy (FESEM) analysis proved interaction of BMSC on TiO 2 nanotubes structure was better than flat titanium (Ti) surface. Also, significant cell adhesion on TiO 2 nanotubes surface during in vitro study revealed that BMSC prone to attach on TiO 2 nanotubes. From the result, it can be conclude that TiO 2 nanotubes are biocompatible to biological environment and become a new generation for advanced implant materials

Anodic Fabrication of Ti-Ni-O Nanotube Arrays on Shape Memory Alloy

Directory of Open Access Journals (Sweden)

Qiang Liu

2014-04-01

Full Text Available Surface modification with oxide nanostructures is one of the efficient ways to improve physical or biomedical properties of shape memory alloys. This work reports a fabrication of highly ordered Ti-Ni-O nanotube arrays on Ti-Ni alloy substrates through pulse anodization in glycerol-based electrolytes. The effects of anodization parameters and the annealing process on the microstructures and surface morphology of Ti-Ni-O were studied using scanning electron microscope and Raman spectroscopy. The electrolyte type greatly affected the formation of nanotube arrays. A formation of anatase phase was found with the Ti-Ni-O nanotube arrays annealed at 450 °C. The oxide nanotubes could be crystallized to rutile phase after annealing treatment at 650 °C. The Ti-Ni-O nanotube arrays demonstrated an excellent thermal stability by keeping their nanotubular structures up to 650 °C.

Improvement of the bio-functional properties of TiO{sub 2} nanotubes

Energy Technology Data Exchange (ETDEWEB)

Roguska, A. [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland); Pisarek, M., E-mail: mpisarek@ichf.edu.pl [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland); Belcarz, A. [Chair and Department of Biochemistry and Biotechnology, Medical University of Lublin, Chodźki 1, 20-093 Lublin (Poland); Marcon, L. [Interdisciplinary Research Institute, USR CNRS 3078 Parc de la Haute Borne, 50 av. de Halley 59658 Villeneuve d’Ascq (France); Holdynski, M. [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland); Andrzejczuk, M. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warsaw (Poland); Janik-Czachor, M. [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland)

2016-12-01

Highlights: • The methods of biofunctional properties improvement of TiO{sub 2} nanotubes are proposed. • The increase of TiO{sub 2} nanotubes diameter promotes the U2OS cell proliferation. • Calcium phosphate coating deposited TiO{sub 2} nanotube layer promotes the cell growth. • Deposition of Ag nanoparticles inhibits the survivability of S. epidermidis cells. - Abstract: Titanium oxide nanotubes with diameters from ca. 40–120 nm fabricated by the anodic oxidation of Ti at a constant voltage (10–28 V) were investigated to identify factors improving their bio-functional properties. Prepared substrates were subsequently annealed at 450 °C and 650 °C to obtain nanotubes having a crystalline structure, and were then examined by SEM, XRD, XPS, BET and contact angle measurement techniques. The thermally stabilized surfaces were subjected to bidirectional functionalization: by deposition of a thin layer of Ca-P and by loading with silver nanoparticles. Three factors were found to promote the proliferation of osteoblast (U2OS) cells: a larger nanotube diameter, a higher annealing temperature, and the presence of a thin Ca-P layer. Differentiation of these cells (by ALP test) was stimulated by a higher (650 °C) nanotube annealing temperature, but not by a thin Ca-P layer. The TiO{sub 2} nanotubes-modified samples exhibited noticeable antibacterial properties. Moreover, the additional deposition of Ag nanoparticles almost completely inhibited the survivability of S. epidermidis cells beyond 3 h of contact. In conclusion, TiO{sub 2} nanotubes-modified surfaces exhibit distinct bone forming ability and significant antibacterial properties, and can be easily functionalized by a thin Ca-P layer or nano-Ag deposition for further improvement of the above functionalities.

Ti/TiO 2 nanotube array electrode as a new sensor to ...

Indian Academy of Sciences (India)

The Ti/TiO2 nanotube array (Ti-NTA) electrode was prepared by anodizing of the Ti foil ... and the pH=3.0 and =1.0 V (vs. reference electrode) were determined as the ... It was found that the photocurrent of EG was linearly dependent on the ...

Anodic Fabrication of Ti-Nb-Zr-O Nanotube Arrays

Directory of Open Access Journals (Sweden)

Qiang Liu

2014-01-01

Full Text Available Highly ordered Ti-Nb-Zr-O nanotube arrays were fabricated through pulse anodic oxidation of Ti-Nb-Zr alloy in 1 M NaH2PO4 containing 0.5 wt% HF electrolytes. The effect of anodization parameters and Zr content on the microstructure and composition of Ti-Nb-Zr-O nanotubes was investigated using a scanning electron microscope equipped with energy dispersive X-ray analysis. It was found that length of the Ti-Nb-Zr-O nanotubes increased with increase of Zr contents. The diameter and the length of Ti-Nb-Zr-O nanotubes could be controlled by pulse voltage. XRD analysis of Ti-Nb-Zr-O samples annealed at 500°C in air indicated that the (101 diffraction peaks shifted from 25.78° to 25.05° for annealed Ti-Nb-Zr-O samples with different Zr contents because of larger lattice parameter of Ti-Nb-Zr-O compared to that of undoped TiO2.

Facile synthesis of SiO{sub 2}@Cu{sub x}O@TiO{sub 2} heterostructures for catalytic reductions of 4-nitrophenol and 2-nitroaniline organic pollutants

Energy Technology Data Exchange (ETDEWEB)

Zelekew, Osman Ahmed; Kuo, Dong-Hau, E-mail: dhkuo@mail.ntust.edu.tw

2017-01-30

Highlights: • The synthesis of SiO{sub 2}@Cu{sub x}O@TiO{sub 2}catalystwasillustrated (*). • The p-n junction between p-type Cu{sub x}O and n-type TiO{sub 2} built electric field. • The electric field results in avoiding the recombination of electron and hole. • The n-type TiO{sub 2} rich in electron outward facilitates the reduction. - Abstract: Herein, we designed the p-type Cu{sub x}O (x = 1 or 2) nanoparticles deposited on SiO{sub 2} spherical particle inside and coated with thin layered n-type TiO{sub 2} semiconductors outside for reduction purpose. The composite material, abbreviated as SiO{sub 2}@Cu{sub x}O@TiO{sub 2}, was characterized. The catalytic performance of the composite was tested for the reductions of 4-nitrophenol (4-NP) and 2-nitroaniline (2-NA). Complete reductions of 4-NP and 2-NA took, 210 and 150 s, respectively. The catalytic efficiency of the composite material may be associated with electron and hole separation resulted from the p-n junction formation between p-type Cu{sub x}O and n-type TiO{sub 2} and the built-in electric field. Moreover, the hydride ion and electrons released from NaBH{sub 4} together with outward electrons from n-type TiO{sub 2}, synergistically, are also responsible for the reduction of nitro aromatic compounds. Our design of composite material from low-priced metal oxides was successful towards reduction of nitro-aromatic compounds.

Formation mechanism of TiO2 nanotubes and their applications in photoelectrochemical water splitting and supercapacitors.

Science.gov (United States)

Chen, Bo; Hou, Junbo; Lu, Kathy

2013-05-14

Structural observations of the transition of TiO2 nanopores into nanotubes by increasing the OH(-) concentration in the electrolyte challenge the validity of existing formation mechanisms of anodic TiO2 nanotubes. In this study, dehydration of titanium hydroxide in the cell wall is proposed as the mechanism that leads to the separation of neighboring nanotubes. Based on this understanding, bamboo-type TiO2 nanotubes with large surface area and excellent interconnectivity are achieved by cycling high and low applied potentials. After thermal treatment in a H2 atmosphere, the bamboo-type TiO2 nanotubes show large photoelectrochemical water splitting efficiency and supercapacitors performace.

Study of TiO{sub 2} nanotubes as an implant application

Energy Technology Data Exchange (ETDEWEB)

Hazan, Roshasnorlyza, E-mail: roshasnorlyza@nm.gov.my; Sreekantan, Srimala [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300, Nibong Tebal, Pulau Pinang (Malaysia); Mydin, Rabiatul Basria S. M. N.; Mat, Ishak [Advanced Medical and Dental Institute, Universiti Sains Malaysia, 13200, Kepala Batas, Pulau Pinang (Malaysia); Abdullah, Yusof [Materials Technology Group, Industrial Technology Division, Nuclear Malaysia Agency, Bangi, 43000, Kajang, Selangor. Malaysia (Malaysia)

2016-01-22

Vertically aligned TiO{sub 2} nanotubes have become the primary candidates for implant materials that can provide direct control of cell behaviors. In this work, 65 nm inner diameters of TiO{sub 2} nanotubes were successfully prepared by anodization method. The interaction of bone marrow stromal cells (BMSC) in term of cell adhesion and cell morphology on bare titanium and TiO{sub 2} nanotubes is reported. Field emission scanning electron microscopy (FESEM) analysis proved interaction of BMSC on TiO{sub 2} nanotubes structure was better than flat titanium (Ti) surface. Also, significant cell adhesion on TiO{sub 2} nanotubes surface during in vitro study revealed that BMSC prone to attach on TiO{sub 2} nanotubes. From the result, it can be conclude that TiO{sub 2} nanotubes are biocompatible to biological environment and become a new generation for advanced implant materials.

Synthesis And Characterization Of SiO2, SnO2 And TiO2 Metal Oxide Shells Covering Cu2O Particles

Directory of Open Access Journals (Sweden)

Yu Ri

2015-06-01

Full Text Available In this work is described a means of improving the chemical stability of Cu2O@SiO2, Cu2O@SnO2 and Cu2O@TiO2 materials. The SiO2, SnO2 and TiO2 coated samples were stable from pH 3 to pH 10 for up to seven days. To determine the stability of the coated nanoparticles, and their colloidal solutions under acidic and basic conditions, colloidal nanoparticle solutions with various pH values were prepared and monitored over time. Details of the effect of variations in pH on the phase stability of core-shell type Cu2O were characterized using transmission electron microscopy and X-ray diffraction.

Flow-Regulated Growth of Titanium Dioxide (TiO2 ) Nanotubes in Microfluidics.

Science.gov (United States)

Fan, Rong; Chen, Xinye; Wang, Zihao; Custer, David; Wan, Jiandi

2017-08-01

Electrochemical anodization of titanium (Ti) in a static, bulk condition is used widely to fabricate self-organized TiO 2 nanotube arrays. Such bulk approaches, however, require extended anodization times to obtain long TiO 2 nanotubes and produce only vertically aligned nanotubes. To date, it remains challenging to develop effective strategies to grow long TiO 2 nanotubes in a short period of time, and to control the nanotube orientation. Here, it is shown that the anodic growth of TiO 2 nanotubes is significantly enhanced (≈16-20 times faster) under flow conditions in microfluidics. Flow not only controls the diameter, length, and crystal orientations of TiO 2 nanotubes, but also regulates the spatial distribution of nanotubes inside microfluidic devices. Strikingly, when a Ti thin film is deposited on silicon substrates and anodized in microfluidics, both vertically and horizontally aligned (relative to the bottom substrate) TiO 2 nanotubes can be produced. The results demonstrate previously unidentified roles of flow in the regulation of growth of TiO 2 nanotubes, and provide powerful approaches to effectively grow long, oriented TiO 2 nanotubes, and construct hierarchical TiO 2 nanotube arrays on silicon-based materials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High pressure synthesis of amorphous TiO2 nanotubes

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Quanjun Li

2015-09-01

Full Text Available Amorphous TiO2 nanotubes with diameters of 8-10 nm and length of several nanometers were synthesized by high pressure treatment of anatase TiO2 nanotubes. The structural phase transitions of anatase TiO2 nanotubes were investigated by using in-situ high-pressure synchrotron X-ray diffraction (XRD method. The starting anatase structure is stable up to ∼20GPa, and transforms into a high-density amorphous (HDA form at higher pressure. Pressure-modified high- to low-density transition was observed in the amorphous form upon decompression. The pressure-induced amorphization and polyamorphism are in good agreement with the previous results in ultrafine TiO2 nanoparticles and nanoribbons. The relationship between the LDA form and α-PbO2 phase was revealed by high-resolution transmission electron microscopy (HRTEM study. In addition, the bulk modulus (B0 = 158 GPa of the anatase TiO2 nanotubes is smaller than those of the corresponding bulks and nanoparticles (180-240 GPa. We suggest that the unique open-ended nanotube morphology and nanosize play important roles in the high pressure phase transition of TiO2 nanotubes.

TiO2 and Cu/TiO2 Thin Films Prepared by SPT

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S. S. Roy

2015-12-01

Full Text Available Titanium oxide (TiO2 and copper (Cu doped titanium oxide (Cu/TiO2 thin films have been prepared by spray pyrolysis technique. Titanium chloride (TiCl4 and copper acetate (Cu(CH3COO2.H2O were used as source of Ti and Cu. The doping concentration of Cu was varied from 1-10 wt. %. The X-ray diffraction studies show that TiO2 thin films are tetragonal structure and Cu/TiO2 thin films implies CuO has present with monoclinic structure. The optical properties of the TiO2 thin films have been investigated as a function of Cu-doping level. The optical transmission of the thin films was found to increase from 88 % to 94 % with the addition of Cu up to 8 % and then decreases for higher percentage of Cu doping. The optical band gap (Eg for pure TiO2 thin film is found to be 3.40 eV. Due to Cu doping, the band gap is shifted to lower energies and then increases further with increasing the concentration of Cu. The refractive index of the TiO2 thin films is found to be 2.58 and the variation of refractive index is observed due to Cu doped. The room temperature resistivity of the films decreases with increasing Cu doping and is found to be 27.50 - 23.76 W·cm. It is evident from the present study that the Cu doping promoted the thin film morphology and thereby it is aspect for various applications.

Application of nitrogen-doped TiO2 nano-tubes in dye-sensitized solar cells

DEFF Research Database (Denmark)

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

2017-01-01

Our research aimed to improve the overall energy conversion efficiency of DSCs by applying nitrogen-doped TiO2 nano-tubes (N-TNT) for the preparation of DSCs photo-anodes. The none-doped TiO2 nano-tubes (TNTs) were synthesized by alkaline hydrothermal treatment of Degussa P25 TiO2 particles in 10...

Solution-processed all-oxide bulk heterojunction solar cells based on CuO nanaorod array and TiO2 nanocrystals

Science.gov (United States)

Wu, Fan; Qiao, Qiquan; Bahrami, Behzad; Chen, Ke; Pathak, Rajesh; Tong, Yanhua; Li, Xiaoyi; Zhang, Tiansheng; Jian, Ronghua

2018-05-01

We present a method to synthesize CuO nanorod array/TiO2 nanocrystals bulk heterojunction (BHJ) on fluorine-tin-oxide (FTO) glass, in which single-crystalline p-type semiconductor of the CuO nanorod array is grown on the FTO glass by hydrothermal reaction and the n-type semiconductor of the TiO2 precursor is filled into the CuO nanorods to form well-organized nano-interpenetrating BHJ after air annealing. The interface charge transfer in CuO nanorod array/TiO2 heterojunction is studied by Kelvin probe force microscopy (KPFM). KPFM results demonstrate that the CuO nanorod array/TiO2 heterojunction can realize the transfer of photo-generated electrons from the CuO nanorod array to TiO2. In this work, a solar cell with the structure FTO/CuO nanoarray/TiO2/Al is successfully fabricated, which exhibits an open-circuit voltage (V oc) of 0.20 V and short-circuit current density (J sc) of 0.026 mA cm‑2 under AM 1.5 illumination. KPFM studies indicate that the very low performance is caused by an undesirable interface charge transfer. The interfacial surface potential (SP) shows that the electron concentration in the CuO nanorod array changes considerably after illumination due to increased photo-generated electrons, but the change in the electron concentration in TiO2 is much less than in CuO, which indicates that the injection efficiency of the photo-generated electrons from CuO to TiO2 is not satisfactory, resulting in an undesirable J sc in the solar cell. The interface photovoltage from the KPFM measurement shows that the low V oc results from the small interfacial SP difference between CuO and TiO2 because the low injected electron concentration cannot raise the Fermi level significantly in TiO2. This conclusion agrees with the measured work function results under illumination. Hence, improvement of the interfacial electron injection is primary for the CuO nanorod array/TiO2 heterojunction solar cells.

Fabrication of Cu2O/TiO2 Nanotubes Heterojunction Arrays and Investigation of Their Photoelectrochemical Behaviour

Science.gov (United States)

2012-11-05

deionized water. Anodizing was conducted in a two-electrode configuration using a platinum mesh as cathode and potential was kept constant during anodizing...investigate phase transformations in TiO2 NTs after annealing and as a consequence of the functionalization. Electrodeposition was performed in a...deposition Cu2O electrodeposition was performed by polarizing the Ti/TiO2 NTs electrodes at UE = - 0.4 V in the CuSO4 containing bath described in

Conducting mechanisms of forming-free TiW/Cu{sub 2}O/Cu memristive devices

Energy Technology Data Exchange (ETDEWEB)

Yan, P.; Li, Y.; Hui, Y. J.; Zhong, S. J.; Zhou, Y. X.; Xu, L.; Liu, N.; Qian, H.; Sun, H. J., E-mail: shj@mail.hust.edu.cn; Miao, X. S. [Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan 430074 (China); School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China)

2015-08-24

P-type Cu{sub 2}O is a promising CMOS-compatible candidate to fabricate memristive devices for next-generation memory, logic and neuromorphic computing. In this letter, the microscopic switching and conducting mechanisms in TiW/Cu{sub 2}O/Cu memristive devices have been thoroughly investigated. The bipolar resistive switching behaviors without an electro-forming process are ascribed to the formation and rupture of the conducting filaments composed of copper vacancies. In the low resistive state, the transport of electrons in the filaments follows Mott's variable range hopping theory. When the devices switch back to high resistive state, the coexistence of Schottky emission at the Cu/Cu{sub 2}O interface and electron hopping between the residual filaments is found to dominate the conducting process. Our results will contribute to the further understanding and optimization of p-type memristive materials.

Synthesis and characterization of Cu{sub 2}O/TiO{sub 2} photocatalysts for H{sub 2} evolution from aqueous solution with different scavengers

Energy Technology Data Exchange (ETDEWEB)

Li, Yanping; Wang, Baowei, E-mail: wangbw@tju.edu.cn; Liu, Sihan; Duan, Xiaofei; Hu, Zongyuan

2015-01-01

Graphical abstract: - Highlights: • Cu{sub 2}O/TiO{sub 2} photocatalyst are prepared by a facile ethanol reduction method. • The heterojunction between p-type Cu{sub 2}O and n-type TiO{sub 2} improves activity of TiO{sub 2}. • An optimal molar fraction of Cu{sub 2}O is reported in Cu{sub 2}O/TiO{sub 2} photocatalysts. • The effect of different alcohols scavengers on activity of Cu{sub 2}O/TiO{sub 2} is discussed. - Abstract: A series of Cu{sub 2}O/TiO{sub 2} photocatalysts with different molar fraction of Cu{sub 2}O were prepared by a facile modified ethanol-induced approach followed by a calcination process. The chemical state of copper compound was proved to be cuprous oxide by the characterization of X-ray photoelectron spectra (XPS). Furthermore, these composite oxides were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N{sub 2} adsorption desorption and UV–vis techniques to study the morphologies, structures, and optical properties of the as-prepared samples. The results indicated that the photocatalytic activity of n-type TiO{sub 2} was significantly enhanced by combined with p-type Cu{sub 2}O, due to the efficient p–n heterojunction. The p–n heterojunction between Cu{sub 2}O and TiO{sub 2} can enhance visible-light adsorption, efficiently suppress charge recombination, improve interfacial charge transfer, and especially provide plentiful reaction active sites on the surface of photocatalyst. As a consequence, the prepared 2.5-Cu{sub 2}O/TiO{sub 2} photocatalyst exhibited the highest photocatalytic activity for H{sub 2} evolution rate and reached 2048.25 μmol/(g h), which is 14.48 times larger than that of pure P25. The apparent quantum yield (AQY) of the 2.5-Cu{sub 2}O/TiO{sub 2} sample at 365 nm was estimated to be 4.32%. In addition, the influence of different scavengers, namely methanol, anhydrous ethanol, ethylene glycol and glycerol, on the photocatalytic activity for H{sub 2} evolution rate was

Low temperature synthesis of polyaniline-crystalline TiO2-halloysite composite nanotubes with enhanced visible light photocatalytic activity.

Science.gov (United States)

Li, Cuiping; Wang, Jie; Guo, Hong; Ding, Shujiang

2015-11-15

A series of one-dimensional polyaniline-crystalline TiO2-halloysite composite nanotubes with different mass ratio of polyaniline to TiO2 are facilely prepared by employing the low-temperature synthesis of crystalline TiO2 on halloysite nanotubes. The halloysite nanotubes can adsorb TiO2/polyaniline precursors and induce TiO2 nanocrystals/polyaniline to grow on the support in situ simultaneously. By simply adjusting the acidity of reaction system, PANI-crystalline TiO2-HA composite nanotubes composed of anatase, a mixed phase TiO2 and different PANI redox state are obtained. The XRD and UV-vis results show that the surface polyaniline sensitization has no effect on the crystalline structure of halloysite and TiO2 and the light response of TiO2 is extended to visible-light regions. Photocatalysis test results reveal the photocatalytic activity will be affected by the pH value and the volume ratio of ANI to TTIP. The highest photocatalytic activity is achieved with the composite photocatalysts prepared at pH 0.5 and 1% volume ratio of ANI and TTIP owing to the sensitizing effect of polyaniline and the charge transfer from the photoexcited PANI sensitizer to TiO2. Moreover, the PANI-TiO2-HA composite nanotubes synthesized by one-step at pH 0.5 with 1% volume ratio of ANI to TTIP exhibit higher visible light photocatalytic activity than those synthesized by the two-step. Heterogeneous PANI-TiO2-HA composite nanotubes prepared at pH 0.5 exhibit a higher degradation activity than that prepared at pH 1.5. The redoped experiment proves that the PANI redox state plays the main contribution to the enhanced visible light catalytic degradation efficiency of PANI-TiO2-HA prepared at pH 0.5. Furthermore, the heterogeneous PANI-crystalline TiO2-HA nanotubes have good photocatalytic stability and can be reused four times with only gradual loss of activity under visible light irradiation. Copyright © 2015 Elsevier Inc. All rights reserved.

Efficient silver modification of TiO2 nanotubes with enhanced photocatalytic activity

Science.gov (United States)

Huang, Jing; Ding, Lei; Xi, Yaoning; Shi, Liang; Su, Ge; Gao, Rongjie; Wang, Wei; Dong, Bohua; Cao, Lixin

2018-06-01

In this paper, Ag(CH3NH2)2+, Ag(NH3)2+ and Ag+ with different radii have been used as silver sources to find out the distribution of Ag ions on the H-TNT surface, which is critical to the final performance. The influence of this distribution on visible photocatalytic activity is further studied. The results indicate that, when Ag+ used as silver source with low concentration, these small sized silver ions mainly distribute on interlayer spacing of H-TNT. After heat-treatment and photo-reduction, the generated silver nanoparticles uniformly embed in the anatase TiO2 nanotube walls, and bring large interfacial area between Ag particles and TiO2 nanotubes. The separation effect of photogenerated electron-hole pair in TiO2 is enhanced by Ag particles, and achieves the best at 0.15 g/L, much higher than P25, TiO2/0, Ag-N@TiO2 and Ag-C-N@TiO2. This paper provides new ideas for the modification of TiO2 nanotubes.

High pressure synthesis of amorphous TiO{sub 2} nanotubes

Energy Technology Data Exchange (ETDEWEB)

Li, Quanjun; Liu, Ran; Wang, Tianyi; Xu, Ke; Dong, Qing; Liu, Bo; Liu, Bingbing, E-mail: liubb@jlu.edu.cn [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Liu, Jing [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

2015-09-15

Amorphous TiO{sub 2} nanotubes with diameters of 8-10 nm and length of several nanometers were synthesized by high pressure treatment of anatase TiO{sub 2} nanotubes. The structural phase transitions of anatase TiO{sub 2} nanotubes were investigated by using in-situ high-pressure synchrotron X-ray diffraction (XRD) method. The starting anatase structure is stable up to ∼20GPa, and transforms into a high-density amorphous (HDA) form at higher pressure. Pressure-modified high- to low-density transition was observed in the amorphous form upon decompression. The pressure-induced amorphization and polyamorphism are in good agreement with the previous results in ultrafine TiO{sub 2} nanoparticles and nanoribbons. The relationship between the LDA form and α-PbO{sub 2} phase was revealed by high-resolution transmission electron microscopy (HRTEM) study. In addition, the bulk modulus (B{sub 0} = 158 GPa) of the anatase TiO{sub 2} nanotubes is smaller than those of the corresponding bulks and nanoparticles (180-240 GPa). We suggest that the unique open-ended nanotube morphology and nanosize play important roles in the high pressure phase transition of TiO{sub 2} nanotubes.

An innovative approach to synthesize highly-ordered TiO2 nanotubes.

Science.gov (United States)

Isimjan, Tayirjan T; Yang, D Q; Rohani, Sohrab; Ray, Ajay K

2011-02-01

An innovative route to prepare highly-ordered and dimensionally controlled TiO2 nanotubes has been proposed using a mild sonication method. The nanotube arrays were prepared by the anodization of titanium in an electrolyte containing 3% NH4F and 5% H2O in glycerol. It is demonstrated that the TiO2 nanostructures has two layers: the top layer is TiO2 nanowire and underneath is well-ordered TiO2 nanotubes. The top layer can easily fall off and form nanowires bundles by implementing a mild sonication after a short annealing time. We found that the dimensions of the TiO2 nanotubes were only dependent on the anodizing condition. The proposed technique may be extended to fabricate reproducible well-ordered TiO2 nanotubes with large area on other metals.

MoSe2 modified TiO2 nanotube arrays with superior photoelectrochemical performance

Science.gov (United States)

Zhang, Yaping; Zhu, Haifeng; Yu, Lianqing; He, Jiandong; Huang, Chengxing

2018-04-01

TiO2 nanotube arrays (TNTs) are first prepared by anodization Ti foils in ethylene glycol electrolyte. Then, MoSe2 deposites electrochemically on TNTs. The as-synthesized MoSe2/TiO2 composite has a much higher photocurrent density of 1.07 mA cm‑2 at 0 V than pure TNTs of 0.38 mA cm‑2, which suggests that the MoSe2/TiO2 composite film has optimum photoelectrocatalysis properties. The electron transport resistances of the MoSe2/TiO2 decreases to half of pure TiO2, at 295.6 ohm/cm2. Both photocurrent-time and Mott-Schottky plots indicate MoSe2 a p-type semiconductor characteristics. MoSe2/TiO2 composite can achieve a maximum 5 orders of magnitude enhancement in carrier density (4.650 × 1027 cm‑3) than that of pure TiO2 arrays. It can be attributed to p-n heterojunction formed between MoSe2 and TiO2, and the composite can be potentially applied in photoelectrochemical, photocatalysis fields.

Synthesis and photocatalytic activity of Ce-doped TiO2 and TiO2 nanotubes

International Nuclear Information System (INIS)

Arruda, L.B.; Pereira, E.A.; Paula, F.R.; Lisboa Filho, P.N.

2016-01-01

samples with pH 7, XRD measurements showed the coexistence of TiO2 and sodium titanate phase. By decreasing the pH during acid washing the sodium content was eliminated leaving only the main phase. This behavior was observed for samples containing Cerium concentrations up to 0.2%. The obtained nanotubes presented multiple walls, having dimensions of 5 nm of diameter and about 200 nm of length. Energy dispersive X-ray spectroscopy analyzes revealed that nanotubes are mainly composed of titanium and oxygen, with small amounts of sodium when pH is 7 and sodium no was observed for the sample obtained at pH 4. It shows that synthesis conditions are very important in order to obtain single-phase structures. In addition, TiO2 nanotubes showed good photocatalytic activity with degradation around 100 minutes.(author)

Synthesis and photocatalytic activity of Ce-doped TiO2 and TiO2 nanotubes

Energy Technology Data Exchange (ETDEWEB)

Arruda, L.B.; Pereira, E.A.; Paula, F.R.; Lisboa Filho, P.N. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), SP (Brazil)

2016-07-01

samples with pH 7, XRD measurements showed the coexistence of TiO2 and sodium titanate phase. By decreasing the pH during acid washing the sodium content was eliminated leaving only the main phase. This behavior was observed for samples containing Cerium concentrations up to 0.2%. The obtained nanotubes presented multiple walls, having dimensions of 5 nm of diameter and about 200 nm of length. Energy dispersive X-ray spectroscopy analyzes revealed that nanotubes are mainly composed of titanium and oxygen, with small amounts of sodium when pH is 7 and sodium no was observed for the sample obtained at pH 4. It shows that synthesis conditions are very important in order to obtain single-phase structures. In addition, TiO2 nanotubes showed good photocatalytic activity with degradation around 100 minutes.(author)

Investigation on the Photoelectrocatalytic Activity of Well-Aligned TiO2 Nanotube Arrays

Directory of Open Access Journals (Sweden)

Xiaomeng Wu

2012-01-01

Full Text Available Well-aligned TiO2 nanotube arrays were fabricated by anodizing Ti foil in viscous F− containing organic electrolytes, and the crystal structure and morphology of the TiO2 nanotube array were characterized and analyzed by XRD, SEM, and TEM, respectively. The photocatalytic activity of the TiO2 nanotube arrays was evaluated in the photocatalytic (PC and photoelectrocatalytic (PEC degradation of methylene blue (MB dye in different supporting solutions. The excellent performance of ca. 97% for color removal was reached after 90 min in the PEC process compared to that of PC process which indicates that a certain external potential bias favors the promotion of the electrode reaction rate on TiO2 nanotube array when it is under illumination. In addition, it is found that PEC process conducted in supporting solutions with low pH and containing Cl− is also beneficial to accelerate the degradation rate of MB.

Investigations of structural, morphological and optical properties of Cu:ZnO/TiO2/ZnO and Cu:TiO2/ZnO/TiO2 thin films prepared by spray pyrolysis technique

Directory of Open Access Journals (Sweden)

M.I. Khan

Full Text Available The aim of this research work is presented a comparison study of Cu:ZnO/TiO2/ZnO (Cu:ZTZ and Cu:TiO2/ZnO/TiO2 (Cu:TZT thin films deposited by spray pyrolysis technique on FTO substrates. After deposition, these films are annealed at 500 °C. XRD confirms the anatase phase of TiO2 and Hexagonal wurtzite phase of ZnO. SEM shows that Cu:TZT has more porous surface than Cu:ZTZ and also the root mean square (RMS roughness of Cu:TZT film is 48.96 and Cu:ZTZ film is 32.69. The calculated optical band gaps of Cu:TZT and Cu:ZTZ thin films are 2.65 eV and 2.6 eV respectively, measured by UV–Vis spectrophotometer. This work provides an environment friendly and low cost use of an abundant material for highly efficient dye sensitized solar cells (DSSCs. Keywords: Multilayer films, ZnO, TiO2, Cu

Synthesis and characterization of Cu2O/TiO2 photocatalysts for H2 evolution from aqueous solution with different scavengers

Science.gov (United States)

Li, Yanping; Wang, Baowei; Liu, Sihan; Duan, Xiaofei; Hu, Zongyuan

2015-01-01

A series of Cu2O/TiO2 photocatalysts with different molar fraction of Cu2O were prepared by a facile modified ethanol-induced approach followed by a calcination process. The chemical state of copper compound was proved to be cuprous oxide by the characterization of X-ray photoelectron spectra (XPS). Furthermore, these composite oxides were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption desorption and UV-vis techniques to study the morphologies, structures, and optical properties of the as-prepared samples. The results indicated that the photocatalytic activity of n-type TiO2 was significantly enhanced by combined with p-type Cu2O, due to the efficient p-n heterojunction. The p-n heterojunction between Cu2O and TiO2 can enhance visible-light adsorption, efficiently suppress charge recombination, improve interfacial charge transfer, and especially provide plentiful reaction active sites on the surface of photocatalyst. As a consequence, the prepared 2.5-Cu2O/TiO2 photocatalyst exhibited the highest photocatalytic activity for H2 evolution rate and reached 2048.25 μmol/(g h), which is 14.48 times larger than that of pure P25. The apparent quantum yield (AQY) of the 2.5-Cu2O/TiO2 sample at 365 nm was estimated to be 4.32%. In addition, the influence of different scavengers, namely methanol, anhydrous ethanol, ethylene glycol and glycerol, on the photocatalytic activity for H2 evolution rate was discussed.

Vascular cell responses to ECM produced by smooth muscle cells on TiO{sub 2} nanotubes

Energy Technology Data Exchange (ETDEWEB)

Shen, Fangyu [School of Life Science and Engineering, Southwest Jiaotong University, Chengdu (China); Key Lab of Advanced Technology of Materials of Education Ministry, Southwest Jiaotong University, Chengdu 610031 (China); Zhu, Ying [School of Life Science and Engineering, Southwest Jiaotong University, Chengdu (China); Key Lab of Advanced Technology of Materials of Education Ministry, Southwest Jiaotong University, Chengdu 610031 (China); Wuhan Dragonbio Orthopedic Products CO., LTD, 18, Qinglnghe Road, Hongshan District, Wuhan 430065 (China); Li, Xin [School of Life Science and Engineering, Southwest Jiaotong University, Chengdu (China); Key Lab of Advanced Technology of Materials of Education Ministry, Southwest Jiaotong University, Chengdu 610031 (China); Luo, Rifang, E-mail: lrifang@126.com [School of Life Science and Engineering, Southwest Jiaotong University, Chengdu (China); Key Lab of Advanced Technology of Materials of Education Ministry, Southwest Jiaotong University, Chengdu 610031 (China); Tu, Qiufen [School of Life Science and Engineering, Southwest Jiaotong University, Chengdu (China); Key Lab of Advanced Technology of Materials of Education Ministry, Southwest Jiaotong University, Chengdu 610031 (China); Laboratory of Biosensing and Micro Mechatronics, Southwest Jiaotong University, Chengdu 610031 (China); Wang, Jin, E-mail: jinxxwang@263.net [School of Life Science and Engineering, Southwest Jiaotong University, Chengdu (China); Key Lab of Advanced Technology of Materials of Education Ministry, Southwest Jiaotong University, Chengdu 610031 (China); Huang, Nan [School of Life Science and Engineering, Southwest Jiaotong University, Chengdu (China); Key Lab of Advanced Technology of Materials of Education Ministry, Southwest Jiaotong University, Chengdu 610031 (China)

2015-09-15

Graphical abstract: - Highlights: • TiO{sub 2} nanotubes with the tube diameter of 30 nm via anodic oxidation was prepared. • SMCs on TiO{sub 2} nanotubes presented enhanced extracellular matrix secreting. • ECM prepared via decellularization retained the components: Fn, Ln and collagen. • ECM-covered TiO{sub 2} nanotubes significantly improved the proliferation of ECs. - Abstract: There is an increasing interest in developing new methods to promote biocompatibility of biomedical materials. The TiO{sub 2} nanotubes with the tube diameter of 30 nm were prepared by anodization. The response behavior of the human umbilical vein endothelial cell (HUVEC) and human umbilical artery smooth muscle cell (HUASMC) to these different nanotube sizes was investigated. Compared to the flat Ti, the growth and viability of HUVEC are prohibited, but there was no significant difference of HUASMC on 30 nm TiO{sub 2} nanotubes. In this study, extracellular matrix (ECM) as a complex cellular environment which provides structural support to cells and regulates the cells functions was further used to modify the biological properties of TiO{sub 2} nanotubes. The ECM secreted from HUASMC was successfully deposited onto the 30 nm TiO{sub 2} nanotubes. Moreover, immunofluorescence staining of common ECM components, such as fibronectin, laminin and type IV collagen, also indicated the successful ECM-covering on nanotube surfaces. Interestingly, the surface of ECM-covered TiO{sub 2} nanotubes significantly improved the proliferation of HUVECs in vitro. This suggested that the ECM secreted from HUASMCs on the TiO{sub 2} nanotubular surface could further improve the HUVECs adhesion and proliferation.

Microstructure and antibacterial property of in situ TiO(2) nanotube layers/titanium biocomposites.

Science.gov (United States)

Cui, C X; Gao, X; Qi, Y M; Liu, S J; Sun, J B

2012-04-01

The TiO(2) nanotube layer was in situ synthesized on the surface of pure titanium by the electrochemical anodic oxidation. The diameter of nano- TiO(2) nanotubes was about 70~100 nm. The surface morphology and phase compositions of TiO(2) nanotube layers were observed and analyzed using the scanning electron microscope (SEM). The important processing parameters, including anodizing voltage, reaction time, concentration of electrolyte, were optimized in more detail. The photocatalytic activity of the nano- TiO(2) nanotube layers prepared with optimal conditions was evaluated via the photodegradation of methylthionine in aqueous solution. The antibacterial property of TiO(2) nanotube layers prepared with optimal conditions was evaluated by inoculating Streptococcus mutans on the TiO(2) nanotube layers in vitro. The results showed that TiO(2) nanotube layers/Ti biocomposites had very good antibacterial activity to resist Streptococcus mutans. As a dental implant biomaterial, in situ TiO(2) nanotube layer/Ti biocomposite has better and wider application prospects. Copyright © 2012 Elsevier Ltd. All rights reserved.

Electrodeposition of flake-like Cu_2O on vertically aligned two-dimensional TiO_2 nanosheet array films for enhanced photoelectrochemical properties

International Nuclear Information System (INIS)

Yang, Lei; Zhang, Miao; Zhu, Kerong; Lv, Jianguo; He, Gang; Sun, Zhaoqi

2017-01-01

Highlights: • Flake-like Cu_2O/TNS with exposed {001} facets constructed p-n heterostructure. • The TNS arrays were used as starting substrates for Cu_2O growth. • The Cu_2O/TNS prepared at −0.4 V exhibits the best photoelectrochemical property. - Abstract: A novel Cu_2O/TNS composite structure of single crystal TiO_2 nanosheet (TNS) arrays decorated with flake-like Cu_2O were synthesized by a facile hydrothermal reaction followed by the electrodeposition process. The effects of deposition potential on the microstructure, morphology, and optical property of the thin films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis spectrophotometer. When the deposition potential is higher than −0.4 V, peaks corresponding to Cu appear, meanwhile, flake-like Cu_2O become agglomerating, and transform into dense Cu_2O particles. Additionally, photoelectrochemical experiments indicate that the films deposited at −0.4 V show the lowest resistivity and highest exciton separation efficiency. This enhanced photoelectrochemical properties can be explained by synergistic effect of p-type flake-like Cu_2O and n-type TiO_2 heterojunctions combined with two-dimensional TiO_2 nanosheet with exposed highly reactive {001} facets.

The effect of nano-TiO2 photocatalysis on the antioxidant activities of Cu, Zn-SOD at physiological pH.

Science.gov (United States)

Zheng, Wen; Zou, Hai-Feng; Lv, Shao-Wu; Lin, Yan-Hong; Wang, Min; Yan, Fei; Sheng, Ye; Song, Yan-Hua; Chen, Jie; Zheng, Ke-Yan

2017-09-01

Security issues of nanoparticles on biological toxicity and potential environmental risk have attracted more and more attention with the rapid development and wide applications of nanotechnology. In this work, we explored the effect and probable mechanism of nano-TiO 2 on antioxidant activity of copper, zinc superoxide dismutase (Cu, Zn-SOD) under natural light and mixed light at physiological pH. Nano-TiO 2 was prepared by sol-hydrothermal method, and then characterized by X-ray Diffraction (XRD) and Transmission electron micrographs (TEM). The Cu, Zn-SOD was purified by sephadex G75 chromatography and qualitatively analyzed by sodium dodecyl sulfate polypropylene amide gel electrophoresis (SDS-PAGE). The effect and mechanism were elucidated base on Fourier Transform Infrared Spectrometer (FT-IR), Circular Dichroism (CD), zeta potential, and electron spin resonance (ESR) methods. Accompanying the results of FT-IR, CD and zeta potential, it could be concluded that nano-TiO 2 had no effect on the antioxidant activity of Cu, Zn-SOD by comparing the relative activity under natural light at physiological pH. But the relative activity of Cu, Zn-SOD significantly decreased along with the increase of nano-TiO 2 concentration under the mixed light. The results of ESR showed the cause of this phenomenon was the Cu(II) in the active site of Cu, Zn-SOD was reduced to Cu(I) by H 2 O 2 and decreased the content of active Cu, Zn-SOD. The reduction can be inhibited by catalase. Excess O 2 ·- produced by nano-TiO 2 photocatalysis under mixed light accumulated a mass of H 2 O 2 through disproportionation reaction in this experimental condition. The results show that nano-TiO 2 cannot affect the antioxidant activity of Cu, Zn-SOD in daily life. The study on the effect of nano-TiO 2 on Cu, Zn-SOD will provide a valid theory support for biological safety and the toxicological effect mechanism of nanomaterials on enzyme. Copyright © 2017 Elsevier B.V. All rights reserved.

TiO{sub 2} nanotubes and mesosponges. Towards solar cells and related applications

Energy Technology Data Exchange (ETDEWEB)

Kim, Doohun

2010-07-06

{sub 2} nanostructure. Using the anodization in a hot phosphate electrolyte, an anodic oxide layer with several tens of micrometers thickness is formed, and by subsequent selective etching treatment of this layer, a connected, ordered and mesoporous TiO{sub 2} network (so called TiO{sub 2} mesosponge layer) is obtained. Over the past 30 years, most of the works for TiO{sub 2} nanostructures have been investigated on conventionally sintered nanoparticles that are typically prepared by chemical synthesis. It is necessary to study anodic TiO{sub 2} layers in the applications for photoactive electrodes. In this work, the use of TiO{sub 2} nanotubes and mesosponges mainly in dye-sensitized solar cells (DSCs) are investigated to understand their physical, chemical and electrochemical behaviors. Additionally, for other related applications based on photoelectrochemistry, three different approaches were addressed with nanotube layers grown i) on TiN to activate photocatalysis in the visible range, ii) on TiW to use in electrochromism and iii) on pure Ti to make an UV induced hydrophilic capillary. In the first part of this work, a Ru-complex photosensitized TiO{sub 2} nanotube layers are used in DSCs. A range of fundamental geometries, crystallinities and chemical dye absorptions of TiO{sub 2} nanotube layers are systematically investigated. In the second part, we introduce three approaches to prepare modified TiO{sub 2} nanotubes with various ideas such as i) anodization of polished Ti foil to eliminate an undesired morphology-''nanograss'', ii) applying alternated voltage to prepare bamboo-type nanotubes and iii) decorating TiO{sub 2} particles on TiO{sub 2} nanotubes. By these simple variations, the geometry and surface properties of the nanotube layers can be altered over a wide range. When these highly aligned, ordered and reinforced geometries are used in DSCs, significant increase in the conversion efficiencies can be achieved - i.e., efficiency

High-efficiency perovskite solar cells based on anatase TiO{sub 2} nanotube arrays

Energy Technology Data Exchange (ETDEWEB)

Huang, Yan, E-mail: huangyan@ecust.edu.cn [School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai 200237 (China); Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Wu, Jiamin; Gao, Di [Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States)

2016-01-01

Perovskite solar cells (PSCs) based on one-dimensional anatase TiO{sub 2} nanotube arrays were prepared by using a two-step deposition method to fill the arrays of TiO{sub 2} nanotubes in different lengths with perovskite. The photovoltaic performance of PSCs was found to be significantly dependent on the length of the TiO{sub 2} nanotubes, and the power conversion efficiency decreased as the length of the TiO{sub 2} nanotubes increased from ~ 0.40 μm to ~ 0.65 and then to ~ 0.93 μm. The PSC fabricated with ~ 0.40 μm-long anatase TiO{sub 2} nanotube arrays yielded a power conversion efficiency of 11.3% and a fill factor of 0.68 under illumination of 100 mW/cm{sup 2} AM 1.5G simulated sunlight, which is significantly higher than previously reported solar cells based on 1-D TiO{sub 2} nanostructures. Incident photon-to-current efficiency and electrochemical impedance spectroscopy measurements indicated that longer TiO{sub 2} nanotubes led to higher recombination losses of charge carriers, possibly due to poor filling of the nanotube arrays with perovskite. - Highlights: • 1D anatase TiO{sub 2} nanotubes were used to fabricate perovskite solar cells. • The best efficiency of 11.3% was achieved with ~ 0.40 μm-long TiO{sub 2} nanotubes. • The efficiency of the devices decreased with increasing TiO{sub 2} nanotube lengths.

Synthesis of TiO2 nanotubes with ZnO nanoparticles to achieve antibacterial properties and stem cell compatibility

Science.gov (United States)

Liu, Wenwen; Su, Penglei; Chen, Su; Wang, Na; Ma, Yuanping; Liu, Yiran; Wang, Jinshu; Zhang, Zhenting; Li, Hongyi; Webster, Thomas J.

2014-07-01

To endow titanium (Ti) with antibacterial properties, different concentrations of zinc oxide (ZnO) nanoparticles were decorated on anodized titanium dioxide (TiO2) nanotubes by a simple hydrothermal treatment method. The particle sizes of ZnO, which were evenly distributed and tightly adherent to the walls of the Ti nanotubes, ranged from 20-50 nm. Results from this study showed that Zn was released from the TiO2 nanotubes in a constant, slow, and biologically inspired manner. Importantly, the results showed that the ZnO decorated TiO2 nanotubular samples inhibited Streptococcus mutants and Porphyromonas gingivalis growth compared to control unmodified Ti samples. Specifically, S. mutants and P. gingivalis growth were both reduced 45-85% on the ZnO decorated Ti samples compared to Ti controls after 7 days of culture. When examining the mechanism of action, it has been further found for the first time that the ZnO decorated Ti samples inhibited the expression of Streptococcus mutans bacterial adhesion genes. Lastly, the results showed that the same samples which decreased bacterial growth the most (0.015 M precursor Zn(NO3)2 samples) did not inhibit mesenchymal stem cell growth compared to Ti controls for up to 7 days. In summary, results from this study showed that compared to plain TiO2 nanotubes, TiO2 decorated with 0.015 M ZnO provided unprecedented antibacterial properties while maintaining the stem cell proliferation capacity necessary for enhancing the use of Ti in numerous medical applications, particularly in dentistry.

Amorphous and crystalline TiO2 nanotube arrays for enhanced Li-ion intercalation properties.

Science.gov (United States)

Guan, Dongsheng; Cai, Chuan; Wang, Ying

2011-04-01

We have employed a simple process of anodizing Ti foils to prepare TiO2 nanotube arrays which show enhanced electrochemical properties for applications as Li-ion battery electrode materials. The lengths and pore diameters of TiO2 nanotubes can be finely tuned by varying voltage, electrolyte composition, or anodization time. The as-prepared nanotubes are amorphous and can be converted into anatase nanotubes with heat treatment at 480 degrees C. Rutile crystallites emerge in the anatase nanotube when the annealing temperature is increased to 580 degrees C, resulting in TiO2 nanotubes of mixed phases. The morphological features of nanotubes remain unchanged after annealing. Li-ion insertion performance has been studied for amorphous and crystalline TiO2 nanotube arrays. Amorphous nanotubes with a length of 3.0 microm and an outer diameter of 125 nm deliver a capacity of 91.2 microA h cm(-2) at a current density of 400 microA cm(-2), while those with a length of 25 microm and an outer diameter of 158 nm display a capacity of 533 microA h cm-2. When the 3-microm long nanotubes become crystalline, they deliver lower capacities: the anatase nanotubes and nanotubes of mixed phases show capacities of 53.8 microA h cm-2 and 63.1 microA h cm(-2), respectively at the same current density. The amorphous nanotubes show excellent capacity retention ability over 50 cycles. The cycled nanotubes show little change in morphology compared to the nanotubes before electrochemical cycling. All the TiO2 nanotubes demonstrate higher capacities than amorphous TiO2 compact layer reported in literature. The amorphous TiO2 nanotubes with a length of 1.9 microm exhibit a capacity five times higher than that of TiO2 compact layer even when the nanotube array is cycled at a current density 80 times higher than that for the compact layer. These results suggest that anodic TiO2 nanotube arrays are promising electrode materials for rechargeable Li-ion batteries.

Adhesion measurement of highly-ordered TiO2 nanotubes on Ti-6Al-4V alloy

Directory of Open Access Journals (Sweden)

Masoud Sarraf

2017-12-01

Full Text Available Self-assembled nanotubular arrays on Ti alloys could be used for more effective implantable devices in various medical approaches. In the present work, the adhesion of TiO2 nanotubes (TiO2 NTs on Ti-6Al-4V (Ti64 was investigated by laser spallation and scratch test techniques. At first, electrochemical anodization was performed in an ammonium fluoride solution dissolved in a 90:10 ethane-1,2-diol (ethylene glycol and water solvent mixture. This process was performed at room temperature (23 °C at a steady potential of 60 V for 1 h. Next, the TiO2 nanotubes layer was heat-treated to improve the adhesion of the coating. The formation of selforganized TiO2 nanotubes as well as the microstructural evolution, are strongly dependent on the processing parameters and subsequent annealing. From microscopic analysis, highly oriented arrays of TiO2 nanotubes were grown by thermal treatment for 90 min at 500 °C. Further heat treatment above 500 °C led to the detachment of the nanotubes and the complete destruction of the nanotubes occurred at temperature above 700 °C. Scratch test analysis over a constant scratch length (1000 µm indicated that the failure point was shifted from 247.4 to 557.9 µm while the adhesion strength was increased from ∼862 to ∼1814 mN after annealing at 500 °C. The adhesion measurement determined by laser spallation technique provided an intrinsic adhesion strength of 51.4 MPa for the TiO2 nanotubes on the Ti64 substrate.

Effect of alkali and heat treatments for bioactivity of TiO{sub 2} nanotubes

Energy Technology Data Exchange (ETDEWEB)

Kim, Seo young, E-mail: mast6269@nate.com [Dept. of Dental Biomaterials and Institute of Bio degradable material, Institute of Oral Bioscience and BK21 plus project, School of Dentistry, Chonbuk National University, Jeonju, 561-756 (Korea, Republic of); Kim, Yu kyoung, E-mail: yk0830@naver.com [Dept. of Dental Biomaterials and Institute of Bio degradable material, Institute of Oral Bioscience and BK21 plus project, School of Dentistry, Chonbuk National University, Jeonju, 561-756 (Korea, Republic of); Park, Il song, E-mail: ilsong@jbnu.ac.kr [Division of Advanced Materials Engineering, Research Center for Advanced Materials Development and Institute of Biodegradable Materials, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Jin, Guang chun, E-mail: jingc88@126.com [Oral Medical College, Beihua University, Jilin City 132013 (China); Bae, Tae sung, E-mail: bts@jbnu.ac.kr [Dept. of Dental Biomaterials and Institute of Bio degradable material, Institute of Oral Bioscience and BK21 plus project, School of Dentistry, Chonbuk National University, Jeonju, 561-756 (Korea, Republic of); Lee, Min ho, E-mail: mh@jbnu.ac.kr [Dept. of Dental Biomaterials and Institute of Bio degradable material, Institute of Oral Bioscience and BK21 plus project, School of Dentistry, Chonbuk National University, Jeonju, 561-756 (Korea, Republic of)

2014-12-01

Highlights: • TiO{sub 2} nanotubes formed via anodization were treated by alkali and heat. • The surface roughness was increased after alkali treatment (p < 0.05). • After alkali and heat treatment, the wettability was better than before treatment. • Alkali treated TiO{sub 2} nanotubes were shown higher HAp formation in SBF. • Heat treatment affected on the attachment of cells for alkali treated nanotubes. - Abstract: In this study, for improving the bioactivity of titanium used as an implant material, alkali and heat treatments were carried out after formation of the nanotubes via anodization. Nanotubes with uniform length, diameter, and thickness were formed by anodization. The alkali and heat-treated TiO{sub 2} nanotubes were covered with the complex network structure, and the Na compound was generated on the surface of the specimens. In addition, after 5 and 10 days of immersion in the SBF, the crystallized OCP and HAp phase was significantly increased on the surface of the alkali-treated TiO{sub 2} nanotubes (PNA) and alkali and heat-treated TiO{sub 2} nanotubes (PNAH) groups. Cell proliferation was decreased due to the formation of amorphous sodium titanate (Na{sub 2}TiO{sub 3}) layer on the surface of the PNA group. However, anatase and crystalline sodium titanate were formed on the surface of the PNAH group after heat treatment at 550 °C, and cell proliferation was improved. Thus, PNA group had higher HAp forming ability in the simulated body fluid. Additional heat treatment affected on enhancement of the bioactivity and the attachment of osteoblasts for PNA group.

Interface architecture determined electrocatalytic activity of Pt on vertically oriented TiO(2) nanotubes.

Science.gov (United States)

Rettew, Robert E; Allam, Nageh K; Alamgir, Faisal M

2011-02-01

The surface atomic structure and chemical state of Pt is consequential in a variety of surface-intensive devices. Herein we present the direct interrelationship between the growth scheme of Pt films, the resulting atomic and electronic structure of Pt species, and the consequent activity for methanol electro-oxidation in Pt/TiO(2) nanotube hybrid electrodes. X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) measurements were performed to relate the observed electrocatalytic activity to the oxidation state and the atomic structure of the deposited Pt species. The atomic structure as well as the oxidation state of the deposited Pt was found to depend on the pretreatment of the TiO(2) nanotube surfaces with electrodeposited Cu. Pt growth through Cu replacement increases Pt dispersion, and a separation of surface Pt atoms beyond a threshold distance from the TiO(2) substrate renders them metallic, rather than cationic. The increased dispersion and the metallic character of Pt results in strongly enhanced electrocatalytic activity toward methanol oxidation. This study points to a general phenomenon whereby the growth scheme and the substrate-to-surface-Pt distance dictates the chemical state of the surface Pt atoms, and thereby, the performance of Pt-based surface-intensive devices.

Influence of anodization parameters on the morphology of TiO 2 nanotube arrays

Science.gov (United States)

Omidvar, Hamid; Goodarzi, Saba; Seif, Ahmad; Azadmehr, Amir R.

2011-07-01

TiO 2 nanotube arrays can be fabricated by electrochemical anodization in organic and inorganic electrolytes. Morphology of these nanotube arrays changes when anodization parameters such as applied voltage, type of electrolyte, time and temperature are varied. Nanotube arrays fabricated by anodization of commercial titanium in electrolytes containing NH 4F solution and either sulfuric or phosphoric acid were studied at room temperature; time of anodization was kept constant. Applied voltage, fluoride ion concentration, and acid concentrations were varied and their influences on TiO 2 nanotubes were investigated. The current density of anodizing was recorded by computer controlled digital multimeter. The surface morphology (top-view) of nanotube arrays were observed by SEM. The nanotube arrays in this study have inner diameters in range of 40-80 nm.

Effect of Cu2O morphology on photocatalytic hydrogen generation and chemical stability of TiO2/Cu2O composite.

Science.gov (United States)

Zhu, Lihong; Zhang, Junying; Chen, Ziyu; Liu, Kejia; Gao, Hong

2013-07-01

Improving photocatalytic activity and stability of TiO2/Cu2O composite is a challenge in generating hydrogen from water. In this paper, the TiO2 film/Cu2O microgrid composite was prepared via a microsphere lithography technique, which possesses a remarkable performance of producing H2 under UV-vis light irradiation, in comparison with pure TiO2 film, Cu2O film and TiO2 film/Cu2O film. More interesting is that in TiO2 film/Cu2O microgrid, photo-corrosion of Cu2O can be retarded. After deposition of Pt on its surface, the photocatalytic activity of TiO2/Cu2O microgrid in producing H2 is improved greatly.

Microstructure development of in situ porous TiO/Cu composites

International Nuclear Information System (INIS)

Qin, Q.D.; Huang, B.W.; Li, W.; Shao, F.

2016-01-01

An in situ porous TiO/Cu composite is successfully prepared using powder metallurgy by the reaction of Ti_2CO and Cu powder. Ti_2CO powder is produced by the carbothermic reduction of titanium dioxide (TiO_2) at 1000 °C. Morphological examination of the composite shows that the porosity of composites lies in the range between 10.2% and 35.2%. As the volume fraction of TiO increases, the size of TiO becomes more fine. Scanning electron microscopy (SEM) of the fracture morphology indicates that TiO particles and the Cu matrix are connected by a Cu–Ti phase. - Highlights: • An porous TiO/Cu composite is successfully prepared by powder metallurgy technology. • The porosity of composites lies in the range between 10.2% and 35.2%. • The TiO particles and the Cu matrix are connected by a Cu-Ti phase.

Microstructure development of in situ porous TiO/Cu composites

Energy Technology Data Exchange (ETDEWEB)

Qin, Q.D., E-mail: 58124812@qq.com [Department of Materials & Metallurgy Engineering, Guizhou Institute of Technology, No.1 Caiguan Road, Guiyang 550003 (China); 2011 Special Functional Materials Collaborative Innovation Center of Guizhou Province, No.1 Caiguan Road, Guiyang 550003 (China); Huang, B.W. [Department of Materials & Metallurgy Engineering, Guizhou Institute of Technology, No.1 Caiguan Road, Guiyang 550003 (China); 2011 Special Functional Materials Collaborative Innovation Center of Guizhou Province, No.1 Caiguan Road, Guiyang 550003 (China); Li, W. [Department of Materials Engineering, Zhengzhou Technology College, No. 81 Zhengshang Road, Zhengzhou, 450051 (China); Shao, F. [2011 Special Functional Materials Collaborative Innovation Center of Guizhou Province, No.1 Caiguan Road, Guiyang 550003 (China)

2016-07-05

An in situ porous TiO/Cu composite is successfully prepared using powder metallurgy by the reaction of Ti{sub 2}CO and Cu powder. Ti{sub 2}CO powder is produced by the carbothermic reduction of titanium dioxide (TiO{sub 2}) at 1000 °C. Morphological examination of the composite shows that the porosity of composites lies in the range between 10.2% and 35.2%. As the volume fraction of TiO increases, the size of TiO becomes more fine. Scanning electron microscopy (SEM) of the fracture morphology indicates that TiO particles and the Cu matrix are connected by a Cu–Ti phase. - Highlights: • An porous TiO/Cu composite is successfully prepared by powder metallurgy technology. • The porosity of composites lies in the range between 10.2% and 35.2%. • The TiO particles and the Cu matrix are connected by a Cu-Ti phase.

Nanoindentation study of the mechanical behavior of TiO2 nanotube arrays

International Nuclear Information System (INIS)

Xu, Y. N.; Wang, M. C.; Oloyede, A.; Bell, J. M.; Yan, C.; Liu, M. N.

2015-01-01

Titanium dioxide (TiO 2 ) nanotube arrays are attracting increasing attention for use in solar cells, lithium-ion batteries, and biomedical implants. To take full advantage of their unique physical properties, such arrays need to maintain adequate mechanical integrity in applications. However, the mechanical performance of TiO 2 nanotube arrays is not well understood. In this work, we investigate the deformation and failure of TiO 2 nanotube arrays using the nanoindentation technique. We found that the load–displacement response of the arrays strongly depends on the indentation depth and indenter shape. Substrate-independent elastic modulus and hardness can be obtained when the indentation depth is less than 2.5% of the array height. The deformation mechanisms of TiO 2 nanotube arrays by Berkovich and conical indenters are closely associated with the densification of TiO 2 nanotubes under compression. A theoretical model for deformation of the arrays under a large-radius conical indenter is also proposed

Optimization of photoelectrochemical water splitting performance on hierarchical TiO 2 nanotube arrays

KAUST Repository

Zhang, Z.

2012-02-10

In this paper, we show that by varying the voltages during two-step anodization the morphology of the hierarchical top-layer/bottom-tube TiO 2 (TiO 2 NTs) can be finely tuned between nanoring/nanotube, nanopore/nanotube, and nanohole-nanocave/nanotube morphologies. This allows us to optimize the photoelectrochemical (PEC) water splitting performance on the hierarchical TiO 2 NTs. The optimized photocurrent density and photoconversion efficiency in this study, occurring on the nanopore/nanotube TiO 2 NTs, were 1.59 mA cm -2 at 1.23 V vs. RHE and 0.84% respectively, which are the highest values ever reported on pristine TiO 2 materials under illumination of AM 1.5G. Our findings contribute to further improvement of the energy conversion efficiency of TiO 2-based devices.

Optimization of photoelectrochemical water splitting performance on hierarchical TiO 2 nanotube arrays

KAUST Repository

Zhang, Z.; Wang, Peng

2012-01-01

In this paper, we show that by varying the voltages during two-step anodization the morphology of the hierarchical top-layer/bottom-tube TiO 2 (TiO 2 NTs) can be finely tuned between nanoring/nanotube, nanopore/nanotube, and nanohole-nanocave/nanotube morphologies. This allows us to optimize the photoelectrochemical (PEC) water splitting performance on the hierarchical TiO 2 NTs. The optimized photocurrent density and photoconversion efficiency in this study, occurring on the nanopore/nanotube TiO 2 NTs, were 1.59 mA cm -2 at 1.23 V vs. RHE and 0.84% respectively, which are the highest values ever reported on pristine TiO 2 materials under illumination of AM 1.5G. Our findings contribute to further improvement of the energy conversion efficiency of TiO 2-based devices.

Photoelectrocatalytic properties of Ag nanoparticles loaded TiO2 nanotube arrays prepared by pulse current deposition

International Nuclear Information System (INIS)

Xie Kunpeng; Sun Lan; Wang Chenglin; Lai Yuekun; Wang Mengye; Chen Hongbo; Lin Changjian

2010-01-01

A pulse current deposition technique was adopted to construct highly dispersed Ag nanoparticles on TiO 2 nanotube arrays which were prepared by the electrochemical anodization. The morphology, crystallinity, elemental composition, and UV-vis absorption of Ag/TiO 2 nanotube arrays were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and diffuse reflectance spectra (DRS). In particular, the photoelectrochemical properties and photoelectrocatalytic activity under UV light irradiation and the photocatalytic activity under visible light irradiation for newly synthesized Ag/TiO 2 nanotube arrays were investigated. The maximum incident photon to charge carrier efficiency (IPCE) value of Ag/TiO 2 nanotube arrays was 51%, much higher than that of pure TiO 2 nanotube arrays. Ag/TiO 2 nanotube arrays exhibited higher photocatalytic activities than the pure TiO 2 nanotube arrays under both UV and visible light irradiation. The photoelectrocatalytic activity of Ag/TiO 2 nanotube arrays under UV light irradiation was 1.6-fold enhancement compared with pure TiO 2 nanotube arrays. This approach can be used in synthesizing various metal-loaded nanotube arrays materials.

Electrocatalytic activity of Pd-loaded Ti/TiO2 nanotubes cathode for TCE reduction in groundwater.

Science.gov (United States)

Xie, Wenjing; Yuan, Songhu; Mao, Xuhui; Hu, Wei; Liao, Peng; Tong, Man; Alshawabkeh, Akram N

2013-07-01

A novel cathode, Pd loaded Ti/TiO2 nanotubes (Pd-Ti/TiO2NTs), is synthesized for the electrocatalytic reduction of trichloroethylene (TCE) in groundwater. Pd nanoparticles are successfully loaded on TiO2 nanotubes which grow on Ti plate via anodization. Using Pd-Ti/TiO2NTs as the cathode in an undivided electrolytic cell, TCE is efficiently and quantitatively transformed to ethane. Under conditions of 100 mA and pH 7, the removal efficiency of TCE (21 mg/L) is up to 91% within 120 min, following pseudo-first-order kinetics with the rate constant of 0.019 min(-1). Reduction rates increase from 0.007 to 0.019 min(-1) with increasing the current from 20 to 100 mA, slightly decrease in the presence of 10 mM chloride or bicarbonate, and decline with increasing the concentrations of sulfite or sulfide. O2 generated at the anode slightly influences TCE reduction. At low currents, TCE is mainly reduced by direct electron transfer on the Pd-Ti/TiO2NT cathode. However, the contribution of Pd-catalytic hydrodechlorination, an indirect reduction mechanism, becomes significant with increasing the current. Compared with other common cathodes, i.e., Ti-based mixed metal oxides, graphite and Pd/Ti, Pd-Ti/TiO2NTs cathode shows superior performance for TCE reduction. Copyright © 2013 Elsevier Ltd. All rights reserved.

Low-Temperature Catalytic Decomposition of 130 Tetra- to Octa-PCDD/Fs Congeners over CuOX and MnOX Modified V2O5/TiO2-CNTs with the Assistance of O3.

Science.gov (United States)

Zhao, Rixiao; Jin, Dongdong; Yang, Hangsheng; Lu, Shengyong; Potter, Phillip M; Du, Cuicui; Peng, Yaqi; Li, Xiaodong; Yan, Jianhua

2016-10-07

In this study, a reliable and steady PCDD/F generation system was utilized to investigate the performance of catalysts, in which 130 congeners of tetra- to octapolychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) vapors were studied under simulated flue gas with/without O 3 . TiO 2 and carbon nanotubes (CNTs) supported vanadium oxides (VO X /TiO 2 -CNTs) modified with MnO X and CuO X , which were reported to be beneficial to the decomposition of model molecules, were found to have a negative effect on the removal of real PCDD/Fs in the simulated flue gas without O 3 . Moreover, the addition of MnO X presented different effects depending on whether CuO X existed in catalysts or not, which was also contrary to its effects on the degradation of model molecules. In an O 3 -containing atmosphere, low chlorination level PCDD/Fs congeners were removed well over VO X -MnO X /TiO 2 -CNTs, while high chlorination level PCDD/Fs congeners were removed well over VO X -CuO X /TiO 2 -CNTs. Fortunately, all PCDD/Fs congeners decomposed well over VO X -MnO X -CuO X /TiO 2 -CNTs. Finally, the effects of tetra- to octachlorination level for the adsorption and degradation behaviors of PCDD/Fs congeners were also investigated.

Effect of gate dielectrics on the performance of p-type Cu2O TFTs processed at room temperature

KAUST Repository

Al-Jawhari, Hala A.

2013-12-01

Single-phase Cu2O films with p-type semiconducting properties were successfully deposited by reactive DC magnetron sputtering at room temperature followed by post annealing process at 200°C. Subsequently, such films were used to fabricate bottom gate p-channel Cu2O thin film transistors (TFTs). The effect of using high-κ SrTiO3 (STO) as a gate dielectric on the Cu2O TFT performance was investigated. The results were then compared to our baseline process which uses a 220 nm aluminum titanium oxide (ATO) dielectric deposited on a glass substrate coated with a 200 nm indium tin oxide (ITO) gate electrode. We found that with a 150 nm thick STO, the Cu2O TFTs exhibited a p-type behavior with a field-effect mobility of 0.54 cm2.V-1.s-1, an on/off ratio of around 44, threshold voltage equaling -0.62 V and a sub threshold swing of 1.64 V/dec. These values were obtained at a low operating voltage of -2V. The advantages of using STO as a gate dielectric relative to ATO are discussed. © (2014) Trans Tech Publications, Switzerland.

Dynamic Hydrogen Production from Methanol/Water Photo-Splitting Using Core@Shell-Structured CuS@TiO2 Catalyst Wrapped by High Concentrated TiO2 Particles

Directory of Open Access Journals (Sweden)

Younghwan Im

2013-01-01

Full Text Available This study focused on the dynamic hydrogen production ability of a core@shell-structured CuS@TiO2 photocatalyst coated with a high concentration of TiO2 particles. The rectangular-shaped CuS particles, 100 nm in length and 60 nm in width, were surrounded by a high concentration of anatase TiO2 particles (>4~5 mol. The synthesized core@shell-structured CuS@TiO2 particles absorbed a long wavelength (a short band gap above 700 nm compared to that pure TiO2, which at approximately 300 nm, leading to easier electronic transitions, even at low energy. Hydrogen evolution from methanol/water photo-splitting over the core@shell-structured CuS@TiO2 photocatalyst increased approximately 10-fold compared to that over pure CuS. In particular, 1.9 mmol of hydrogen gas was produced after 10 hours when 0.5 g of 1CuS@4TiO2 was used at pH = 7. This level of production was increased to more than 4-fold at higher pH. Cyclic voltammetry and UV-visible absorption spectroscopy confirmed that the CuS in CuS@TiO2 strongly withdraws the excited electrons from the valence band in TiO2 because of the higher reduction potential than TiO2, resulting in a slower recombination rate between the electrons and holes and higher photoactivity.

Catalytic decomposition of gaseous 1,2-dichlorobenzene over CuOx/TiO₂ and CuOx/TiO₂-CNTs catalysts: Mechanism and PCDD/Fs formation.

Science.gov (United States)

Wang, Qiu-lin; Huang, Qun-xing; Wu, Hui-fan; Lu, Sheng-yong; Wu, Hai-long; Li, Xiao-dong; Yan, Jian-hua

2016-02-01

Gaseous 1,2-dichlorobenzene (1,2-DCBz) was catalytically decomposed in a fixed-bed catalytic reactor using composite copper-based titanium oxide (CuOx/TiO2) catalysts with different copper ratios. Carbon nanotubes (CNTs) were introduced to produce novel CuOx/TiO2-CNTs catalysts by the sol-gel method. The catalytic performances of CuOx/TiO2 and CuOx/TiO2-CNTs on 1,2-DCBz oxidative destruction under different temperatures (150-350 °C) were experimentally examined and the correlation between catalyst structure and catalytic activity was characterized and the role of oxygen in catalytic reaction was discussed. Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) generation during 1,2-DCBz catalytic oxidation by CuOx/TiO2-CNTs composite catalyst was also examined. Results indicate that the 1,2-DCBz destruction/removal efficiencies of CuOx (4 wt%)/TiO2 catalyst at 150 °C and 350 °C with a GHSV of 3400 h(-1) are 59% and 94% respectively and low-temperature (150 °C) catalytic activity of CuOx/TiO2 on 1,2-DCBz oxidation can be improved from 59 to 77% when CNTs are introduced. Furthermore, oxygen either in catalyst or from reaction atmosphere is indispensible in reaction. The former is offered to activate and oxidize the 1,2-DCBz adsorbed on catalyst, thus can be generally consumed during reaction and the oxygen content in catalyst is observed lost from 39.9 to 35.0 wt% after reacting under inert atmosphere; the latter may replenish the vacancy in catalyst created by the consumed oxygen thus extends the catalyst life and raises the destruction/removal efficiency. The introduction of CNTs also increases the Cu(2+)/Cu(+) ratio, chemisorbed oxygen concentration and surface lattice oxygen binding energy which are closely related with catalytic activity. PCDD/Fs is confirmed to be formed when 1,2-DCBz catalytically oxidized by CuOx/TiO2-CNTs composite catalyst with sufficient oxygen (21%), proper temperature (350 °C) and high concentration of 1,2-DCBz feed (120 ppm

Photocatalytic degradation of textile dyestuffs using TiO{sub 2} nanotubes prepared by sonoelectrochemical method

Energy Technology Data Exchange (ETDEWEB)

Tekin, Derya, E-mail: deryatekin@atauni.edu.tr

2014-11-01

Highlights: • TiO{sub 2} nanotubes prepared by electrochemical and sonoelectrochemical method. • More regular TiO{sub 2} nanotubes diameters prepared by sonoelectrochemical method. • Obtained nanotubes were used in the photocatalytic degradation of Orange G dye. • TiO{sub 2} nanotubes prepared by sonoelectrochemical method showed 10% faster degradation of Orange G dye compared with the one by electrochemical method. - Abstract: TiO{sub 2} nanotubes were prepared by anodization of Ti plates by conventional electrochemical technique as well as by an emerging sonoelectrochemical technique. Scanning electron miscroscope (SEM) analysis showed that ultrasound assisted anodization yielded more ordered and controllable TiO{sub 2} tube banks with higher tube diameter. The photocatalytical activities of TiO{sub 2} nanotubes were tested in the photocatalytical degradation of Orange G dye. The results showed that sonoelectrochemically prepared TiO{sub 2} tubes exhibited 10% higher photocatalytic performance than the electrochemical prepared ones, and more than 18% higher activity than the other TiO{sub 2} samples.

A mechanistic study on templated electrodeposition of one-dimensional TiO2 nanorods and nanotubes using TiOSO4 as a precursor

KAUST Repository

Teo, Gladys Y.

2014-10-01

One-dimensional (1D) TiO2 nanorods and nanotubes have been successfully synthesized by templated electrodeposition within an anodic aluminium oxide membrane (AAM) using an aqueous precursor containing TiOSO 4. The deposition voltages were found to influence the resultant nanostructure of TiO2. Using a precursor of aqueous TiOSO4 at pH 3 maintained at 10 °C, TiO2 nanorods were electrodeposited in the AAM between applied voltages of - 1.4 V to - 1.0 V (vs. Ag/AgCl), while TiO2 nanotubes were obtained at less negative voltages of - 1.0 V to - 0.3 V (vs. Ag/AgCl). Cyclic voltammetry (CV) revealed that nitrate reduction in the voltage range of - 0.3 V to - 1.4 V played an essential role in the formation of TiO2. The mechanism for TiO2 nanotube formation has been elucidated, paving the way for the future tailoring of metal oxide nanostructures by templated electrodeposition. © 2014 Elsevier B.V.

A mechanistic study on templated electrodeposition of one-dimensional TiO2 nanorods and nanotubes using TiOSO4 as a precursor

KAUST Repository

Teo, Gladys Y.; Ryan, Mary P.; Riley, D. Jason

2014-01-01

One-dimensional (1D) TiO2 nanorods and nanotubes have been successfully synthesized by templated electrodeposition within an anodic aluminium oxide membrane (AAM) using an aqueous precursor containing TiOSO 4. The deposition voltages were found to influence the resultant nanostructure of TiO2. Using a precursor of aqueous TiOSO4 at pH 3 maintained at 10 °C, TiO2 nanorods were electrodeposited in the AAM between applied voltages of - 1.4 V to - 1.0 V (vs. Ag/AgCl), while TiO2 nanotubes were obtained at less negative voltages of - 1.0 V to - 0.3 V (vs. Ag/AgCl). Cyclic voltammetry (CV) revealed that nitrate reduction in the voltage range of - 0.3 V to - 1.4 V played an essential role in the formation of TiO2. The mechanism for TiO2 nanotube formation has been elucidated, paving the way for the future tailoring of metal oxide nanostructures by templated electrodeposition. © 2014 Elsevier B.V.

Toxicity of nanoparticles of CuO, ZnO and TiO2 to microalgae Pseudokirchneriella subcapitata.

Science.gov (United States)

Aruoja, Villem; Dubourguier, Henri-Charles; Kasemets, Kaja; Kahru, Anne

2009-02-01

Toxicities of ZnO, TiO2 and CuO nanoparticles to Pseudokirchneriella subcapitata were determined using OECD 201 algal growth inhibition test taking in account potential shading of light. The results showed that the shading effect by nanoparticles was negligible. ZnO nanoparticles were most toxic followed by nano CuO and nano TiO2. The toxicities of bulk and nano ZnO particles were both similar to that of ZnSO4 (72 h EC50 approximately 0.04 mg Zn/l). Thus, in this low concentration range the toxicity was attributed solely to solubilized Zn2+ ions. Bulk TiO2 (EC50=35.9 mg Ti/l) and bulk CuO (EC50=11.55 mg Cu/l) were less toxic than their nano formulations (EC50=5.83 mg Ti/l and 0.71 mg Cu/l). NOEC (no-observed-effect-concentrations) that may be used for risk assessment purposes for bulk and nano ZnO did not differ (approximately 0.02 mg Zn/l). NOEC for nano CuO was 0.42 mg Cu/l and for bulk CuO 8.03 mg Cu/l. For nano TiO2 the NOEC was 0.98 mg Ti/l and for bulk TiO2 10.1 mg Ti/l. Nano TiO2 formed characteristic aggregates entrapping algal cells that may contribute to the toxic effect of nano TiO2 to algae. At 72 h EC50 values of nano CuO and CuO, 25% of copper from nano CuO was bioavailable and only 0.18% of copper from bulk CuO. Thus, according to recombinant bacterial and yeast Cu-sensors, copper from nano CuO was 141-fold more bioavailable than from bulk CuO. Also, toxic effects of Cu oxides to algae were due to bioavailable copper ions. To our knowledge, this is one of the first systematic studies on effects of metal oxide nanoparticles on algal growth and the first describing toxic effects of nano CuO towards algae.

Electrodeposition of flake-like Cu{sub 2}O on vertically aligned two-dimensional TiO{sub 2} nanosheet array films for enhanced photoelectrochemical properties

Energy Technology Data Exchange (ETDEWEB)

Yang, Lei [School of Physics & Material Science, Anhui University, Hefei 230601 (China); Co-operative Innovation Research Center for Weak Signal-Detecting Materials and Devices Integration, Anhui University, Hefei 230601 (China); Institute of Applied Physics AOA, Hefei 230031 (China); Zhang, Miao; Zhu, Kerong [School of Physics & Material Science, Anhui University, Hefei 230601 (China); Lv, Jianguo [School of Electronic & Information Engineering, Hefei Normal University, Hefei 230601 (China); He, Gang [School of Physics & Material Science, Anhui University, Hefei 230601 (China); Sun, Zhaoqi, E-mail: szq@ahu.edu.cn [School of Physics & Material Science, Anhui University, Hefei 230601 (China)

2017-01-01

Highlights: • Flake-like Cu{sub 2}O/TNS with exposed {001} facets constructed p-n heterostructure. • The TNS arrays were used as starting substrates for Cu{sub 2}O growth. • The Cu{sub 2}O/TNS prepared at −0.4 V exhibits the best photoelectrochemical property. - Abstract: A novel Cu{sub 2}O/TNS composite structure of single crystal TiO{sub 2} nanosheet (TNS) arrays decorated with flake-like Cu{sub 2}O were synthesized by a facile hydrothermal reaction followed by the electrodeposition process. The effects of deposition potential on the microstructure, morphology, and optical property of the thin films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis spectrophotometer. When the deposition potential is higher than −0.4 V, peaks corresponding to Cu appear, meanwhile, flake-like Cu{sub 2}O become agglomerating, and transform into dense Cu{sub 2}O particles. Additionally, photoelectrochemical experiments indicate that the films deposited at −0.4 V show the lowest resistivity and highest exciton separation efficiency. This enhanced photoelectrochemical properties can be explained by synergistic effect of p-type flake-like Cu{sub 2}O and n-type TiO{sub 2} heterojunctions combined with two-dimensional TiO{sub 2} nanosheet with exposed highly reactive {001} facets.

Controlled Directional Growth of TiO2 Nanotubes

DEFF Research Database (Denmark)

In, Su-il; Hou, Yidong; Abrams, Billie

2010-01-01

We demonstrate how the anodization direction and growth rate of vertically aligned, highly ordered TiO2 nanotube (NT) arrays can be controlled and manipulated by the local concentration of O-2 in the electrolyte. This leads to the growth of highly active TiO2 NT arrays directly on nonconducting s...

Flexible symmetric supercapacitors based on vertical TiO2 and carbon nanotubes

Science.gov (United States)

Chien, C. J.; Chang, Pai-Chun; Lu, Jia G.

2010-03-01

Highly conducting and porous carbon nanotubes are widely used as electrodes in double-layer-effect supercapacitors. In this presentation, vertical TiO2 nanotube array is fabricated by anodization process and used as supercapacitor electrode utilizing its compact density, high surface area and porous structure. By spin coating carbon nanotube networks on vertical TiO2 nanotube array as electrodes with 1M H2SO4 electrolyte in between, the specific capacitance can be enhanced by 30% compared to using pure carbon nanotube network alone because of the combination of double layer effect and redox reaction from metal oxide materials. Based on cyclic voltammetry and galvanostatic charge-discharge measurements, this type of hybrid electrode has proven to be suitable for high performance supercapacitor application and maintain desirable cycling stability. The electrochemical impedance spectroscopy technique shows that the electrode has good electrical conductivity. Furthermore, we will discuss the prospect of extending this energy storage approach in flexible electronics.

Novel bamboo structured TiO2 nanotubes for energy storage/production applications

Science.gov (United States)

Samuel, J. J.; Beh, K. P.; Cheong, Y. L.; Yusuf, W. A. A.; Yam, F. K.

2018-04-01

Nanostructured TiO2 received much attention owing to its high surface-to-volume ratio, which can be advantageous in energy storage and production applications. However, the increase in energy consumption at present and possibly the foreseeable future has demanded energy storage and production devices of even higher performance. A direct approach would be manipulating the physical aspects of TiO2 nanostructures, particularly, nanotubes. In this work, dual voltage anodization system has been implemented to fabricate bamboo shaped TiO2 nanotubes, which offers even greater surface area. This unique nanostructure would be used in Dye Sensitized Solar Cell (DSSC) fabrication and its performance will be evaluated and compared along other forms of TiO2 nanotubes. The results showed that bamboo shaped nanotubes indeed are superior morphologically, with an increase of efficiency of 107% at 1.130% efficiency when compared to smooth walled nanotubes at 0.546% efficiency.

Development of a Low-Cost TiO2/CuO/Cu Solar Cell by using Combined Spraying and Electroplating Method

Directory of Open Access Journals (Sweden)

Mamat Rokhmat

2018-03-01

Full Text Available A simple method is proposed to develop a low-cost TiO2/CuO/Cu based solar cell. The cell is made by employing a lower grade (technical grade of TiO2 as the active material. CuO powder is synthesized using a wet chemical method and mixed with TiO2 powder to give impurity to the TiO2. A layer of TiO2/CuO is then deposited onto fluorin-doped tin oxide (FTO by spraying. Copper particles are grown on the spaces between the TiO2 and/or CuO particles by electroplating for more feasible electron migration. The TiO2/CuO/Cu solar cell is finalized by sandwiching a polymer electrolyte between the film and the counter electrode. Current-voltage measurement was performed for various parameters, such as the molarity of NaOH for producing CuO particles, the weight ratio of CuO over TiO2, and the current in the electroplating process. A highest efficiency of 1.40% and a fill factor of 0.37 were achieved by using this combined spray and electroplating method.

Nanoindentation study of the mechanical behavior of TiO{sub 2} nanotube arrays

Energy Technology Data Exchange (ETDEWEB)

Xu, Y. N.; Wang, M. C.; Oloyede, A.; Bell, J. M.; Yan, C., E-mail: c2.yan@qut.edu.au [School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology (QUT), Brisbane, Queensland 4001 (Australia); Liu, M. N. [i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science, Suzhou (China)

2015-10-14

Titanium dioxide (TiO{sub 2}) nanotube arrays are attracting increasing attention for use in solar cells, lithium-ion batteries, and biomedical implants. To take full advantage of their unique physical properties, such arrays need to maintain adequate mechanical integrity in applications. However, the mechanical performance of TiO{sub 2} nanotube arrays is not well understood. In this work, we investigate the deformation and failure of TiO{sub 2} nanotube arrays using the nanoindentation technique. We found that the load–displacement response of the arrays strongly depends on the indentation depth and indenter shape. Substrate-independent elastic modulus and hardness can be obtained when the indentation depth is less than 2.5% of the array height. The deformation mechanisms of TiO{sub 2} nanotube arrays by Berkovich and conical indenters are closely associated with the densification of TiO{sub 2} nanotubes under compression. A theoretical model for deformation of the arrays under a large-radius conical indenter is also proposed.

Improving the Osteoblast Cell Adhesion on Electron Beam Controlled TiO2 Nanotubes

Directory of Open Access Journals (Sweden)

Sung Wook Yoon

2014-01-01

Full Text Available Here we investigate the osteogenesis and synostosis processes on the surface-modified TiO2 nanotubes via electron beam irradiation. The TiO2 nanotubes studied were synthesized by anodization process under different anodizing voltage. For the anodization voltage of 15, 20, and 25 V, TiO2 nanotubes with diameters of 59, 82, and 105 nm and length of 115, 276, and 310 nm were obtained, respectively. MC3T3-E1 osteoblast cell line was incubated on the TiO2 nanotubes to monitor the change in the cell adhesion before and after the electron beam irradiation. We observe that the electron beam irradiation affects the number of surviving osteoblast cells as well as the cultivation time. In particular, the high adhesion rate of 155% was obtained when the osteoblast cells were cultivated for 2 hours on the TiO2 nanotube, anodized under 20 V, and irradiated with 5,000 kGy of electron beam.

Synthesis and Characterization of Hierarchical Structured TiO2 Nanotubes and Their Photocatalytic Performance on Methyl Orange

Directory of Open Access Journals (Sweden)

Kai Liu

2015-01-01

Full Text Available Hierarchical structured TiO2 nanotubes were prepared by mechanical ball milling of highly ordered TiO2 nanotube arrays grown by electrochemical anodization of titanium foil. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, specific surface area analysis, UV-visible absorption spectroscopy, photocurrent measurement, photoluminescence spectra, electrochemical impedance spectra, and photocatalytic degradation test were applied to characterize the nanocomposites. Surface area increased as the milling time extended. After 5 h ball milling, TiO2 hierarchical nanotubes exhibited a corn-like shape and exhibited enhanced photoelectrochemical activity in comparison to commercial P25. The superior photocatalytic activity is suggested to be due to the combined advantages of high surface area of nanoparticles and rapid electron transfer as well as collection of the nanotubes in the hierarchical structure. The hierarchical structured TiO2 nanotubes could be applied into flexible applications on solar cells, sensors, and other photoelectrochemical devices.

The effects of nanostructures on the mechanical and tribological properties of TiO2 nanotubes

Science.gov (United States)

Yoon, Yeoungchin; Park, Jeongwon

2018-04-01

TiO2 nanotubes were prepared by anodization on Ti substrates with a diameter variation of 30-100 nm, and the structure of the nanotubes were studied using x-ray diffraction and Raman spectroscopy, which confirmed the structure changes from the anatase phase to the rutile phase of TiO2 at a diameter below 50 nm. The tribological behaviors of TiO2 nanotubes were investigated with different diameters. The effectiveness of the rutile phase and the diameter size enhanced the frictional performance of TiO2 nanotubes.

Hydrothermal transformation of titanate nanotubes into single-crystalline TiO2 nanomaterials with controlled phase composition and morphology

International Nuclear Information System (INIS)

Xu, Yuanmei; Fang, Xiaoming; Xiong, Jian; Zhang, Zhengguo

2010-01-01

Single-crystalline TiO 2 nanomaterials were synthesized by hydrothermally treating suspensions of H-titanate nanotubes and characterized by XRD, TEM, and HRTEM. The effects of the pH values of the suspensions and the hydrothermal temperatures on the phase composition and morphology of the obtained TiO 2 nanomaterials were systematically investigated. The H-titanate nanotubes were predominately transformed into anatase nanoparticle with rhombic shape when the pH value was greater than or equal to 1.0, whereas primarily turned into rutile nanorod with two pyramidal ends at the pH value less than or equal to 0.5. We propose a possible mechanism for hydrothermal transformation of H-titanate nanotubes into single-crystalline TiO 2 nanomaterials. While the H-titanate nanotubes transform into tiny anatase nanocrystallites of ca. 3 nm in size, the formed nanocrystallites as an intermediate grow into the TiO 2 nanomaterials with controlled phase composition and morphology. This growth process involves the steps of protonation, oriented attachment, and Ostwald ripening.

Guided proliferation and bone-forming functionality on highly ordered large diameter TiO2 nanotube arrays

International Nuclear Information System (INIS)

Zhang, Ruopeng; Wu, Hongliu; Ni, Jiahua; Zhao, Changli; Chen, Yifan; Zheng, Chengjunyi; Zhang, Xiaonong

2015-01-01

The significantly enhanced osteoblast adhesion, proliferation and alkaline phosphatase (ALP) activity were observed on TiO 2 nanotube surface in recent studies in which the scale of nanotube diameter was restricted under 100 nm. In this paper, a series of highly ordered TiO 2 nanotube arrays with larger diameters ranging from 150 nm to 470 nm were fabricated via high voltage anodization. The behaviors of MC3T3-E1 cells in response to the diameter-controlled TiO 2 nanotubes were investigated. A contrast between the trend of proliferation and the trend of cell elongation was observed. The highest cell elongation (nearly 10:1) and the lowest cell number were observed on the TiO 2 nanotube arrays with 150 nm diameter. While, the lowest cell elongation and highest cell number were achieved on the TiO 2 nanotube arrays with 470 nm diameter. Furthermore, the ALP activity peaked on the 150 nm diameter TiO 2 nanotube arrays and decreased dramatically with the increase of nanotube diameter. Thus a narrow range of diameter (100–200 nm) that could induce the greatest bone-forming activity is determined. It is expected that more delicate design of orthopedic implant with regional abduction of cell proliferation or bone forming could be achieved by controlling the diameter of TiO 2 nanotubes. - Highlights: • Improved anodization methods leading to more ordered large diameter TiO 2 nanotubes • Significantly enhanced ALP activity was observed on 150 nm diameter TiO 2 nanotubes. • The highest cell density was observed on 470 nm diameter TiO 2 nanotube arrays. • Similar cell response was observed on the amorphous and anatase phased nanotube surface

Hydrogenated TiO2 nanotube photonic crystals for enhanced photoelectrochemical water splitting.

Science.gov (United States)

Meng, Ming; Zhou, Sihua; Yang, Lun; Gan, Zhixing; Liu, Kuili; Tian, Fengshou; Zhu, Yu; Li, ChunYang; Liu, Weifeng; Yuan, Honglei; Zhang, Yan

2018-04-02

We report the design, fabrication and characterization of novel TiO 2 nanotube photonic crystals with a crystalline core/disordered shell structure as well as substantial oxygen vacancies for photoelectrochemical (PEC) water splitting. The novel TiO 2 nanotube photonic crystals are fabricated by annealing of anodized TiO 2 nanotube photonic crystals in hydrogen atmosphere at various temperatures. The optimized novel TiO 2 nanotube photonic crystals produce a maximal photocurrent density of 2.2 mA cm -2 at 0.22 V versus Ag/AgCl, which is two times higher that of the TiO 2 nanotube photonic crystals annealed in air. Such significant PEC performance improvement can be ascribed to synergistic effects of the disordered surface layer and oxygen vacancies. The reduced band gap owing to the disordered surface layer and localized states induced by oxygen vacancies can enhance the efficient utilization of visible light. In addition, the disordered surface layer and substantial oxygen vacancies can promote the efficiency for separation and transport of the photogenerated carriers. This work may open up new opportunities for the design and construction of the high efficient and low-cost PEC water splitting system.

Influence of the Ti microstructure on anodic self-organized TiO{sub 2} nanotube layers produced in ethylene glycol electrolytes

Energy Technology Data Exchange (ETDEWEB)

Macak, J.M., E-mail: jan.macak@upce.cz [Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, 53002 Pardubice (Czech Republic); Jarosova, M. [Laboratory of Nanostructures and Nanomaterials, Institute of Physics of the CAS, v.v.i., Na Slovance 2, 18221 Prague 8 (Czech Republic); Jäger, A. [Department of Structure analysis, Institute of Physics of the CAS, v.v.i., Cukrovarnicka 10, 16200 Prague 6 (Czech Republic); Sopha, H. [Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, 53002 Pardubice (Czech Republic); Klementová, M. [Institute of Inorganic Chemistry of the CAS, v.v.i., Husinec-Rez 1001, Rez 25068 (Czech Republic)

2016-05-15

Highlights: • The microstructure of Ti substrates investigated by EBSD. • Comparison of polished vs. unpolished substrates was carried out. • Grain orientation influences the uniformity of self-organized TiO{sub 2} nanotubes. • Tubes with different average diameter grow on grains with different orientation. • Grain size and boundaries influence the number of flaws in the tube layers. - Abstract: The relationship between the microstructure of Ti substrates and the anodic growth of self-organized TiO{sub 2} nanotube layers obtained upon their anodization in the ethylene glycol based electrolytes on these substrates is reported for the first time. Polished Ti sheets with mirror-like surface as well as unpolished Ti foils were considered in this work. Grains with a wide range of crystallographic orientations and sizes were revealed by Electron Backscatter Diffraction (EBSD) and correlated with nanotube growth on both types of substrates. A preferred grain orientation with [0 0 0 1] axis perpendicular to the surface was observed on all substrates. Surfaces of all substrates were anodized for 18 h in ethylene glycol electrolytes containing 88 mM NH{sub 4}F and 1.5% water and thoroughly inspected by SEM. By a precise comparison of Ti substrates before and after anodization, the uniformity of produced self-organized TiO{sub 2} nanotube layers was evaluated in regard to the specific orientation of individual grains. Grains with [0 0 0 1] axis perpendicular to the surface turned out to be the most growth-promoting orientation on polished substrates. No orientation was found to be strictly growth-retarding, but sufficient anodization time (24 h) was needed to obtain uniform nanotube layers on all grains without remnant porous initial oxide. In contrast with polished Ti sheets, no specific orientation was found to significantly promote or retard the nanotube growth in the case of unpolished Ti foils. Finally, the difference between the average nanotube diameters of

Porous SnO2-CuO nanotubes for highly reversible lithium storage

Science.gov (United States)

Cheong, Jun Young; Kim, Chanhoon; Jung, Ji-Won; Yoon, Ki Ro; Kim, Il-Doo

2018-01-01

Facile synthesis of rationally designed structures is critical to realize a high performance electrode for lithium-ion batteries (LIBs). Among different candidates, tin(IV) oxide (SnO2) is one of the most actively researched electrode materials due to its high theoretical capacity (1493 mAh g-1), abundance, inexpensive costs, and environmental friendliness. However, severe capacity decay from the volume expansion and low conductivity of SnO2 have hampered its use as a feasible electrode for LIBs. Rationally designed SnO2-based nanostructures with conductive materials can be an ideal solution to resolve such limitations. In this work, we have successfully fabricated porous SnO2-CuO composite nanotubes (SnO2-CuO p-NTs) by electrospinning and subsequent calcination step. The porous nanotubular structure is expected to mitigate the volume expansion of SnO2, while the as-formed Cu from CuO upon lithiation allows faster electron transport by improving the low conductivity of SnO2. With a synergistic effect of both Sn and Cu-based oxides, SnO2-CuO p-NTs deliver stable cycling performance (91.3% of capacity retention, ∼538 mAh g-1) even after 350 cycles at a current density of 500 mA g-1, along with enhanced rate capabilities compared with SnO2.

Photoelectrocatalytic degradation of atrazine by boron-fluorine co-doped TiO2 nanotube arrays.

Science.gov (United States)

Wang, He-Xuan; Zhu, Li-Nan; Guo, Fu-Qiao

2018-06-23

Atrazine, one of the most widespread herbicides in the world, is considered as an environmental estrogen and has potential carcinogenicity. In this study, atrazine was degraded on boron-fluorine co-doped TiO 2 nanotube arrays (B, F-TiO 2 NTAs), which had similar morphology with the pristine TiO 2 NTAs. The structure and morphology of TiO 2 nanotube samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-visible diffuse reflectance spectroscopy (DRS). It showed that the decoration of fluorine and boron made both the absorption in the visible region enhanced and the band edge absorption shifted. The efficiency of atrazine degradation by B, F-TiO 2 NTAs through photoelectrocatalysis was investigated by current, solution pH, and electrolyte concentration, respectively. The atrazine removal rate reached 76% through photoelectrocatalytic reaction by B, F-TiO 2 NTAs, which was 46% higher than that under the photocatalysis process. Moreover, the maximum degradation rate was achieved at pH of 6 in 0.01 M of Na 2 SO 4 electrolyte solution under a current of 0.02 A and visible light for 2 h in the presence of B, F-TiO 2 NTAs. These results showed that B, F-TiO 2 NTAs exhibit remarkable photoelectrocatalytic activity in degradation of atrazine.

Synthesis of highly ordered TiO2 nanotube in malonic acid solution by anodization.

Science.gov (United States)

Ryu, Won Hee; Park, Chan Jin; Kwon, Hyuk Sang

2008-10-01

We synthesized TiO2 nanotube array by anodizing in a solution of malonic acid (HOOCCH2COOH) and NH4F, and analyzed the morphology of the nanotube using scanning electron microscopy (SEM). The morphology of TiO2 nanotube was largely affected by anodizing time, anodizing voltage, and malonic acid concentration. With increasing the anodizing voltage from 5 V to 20 V, the diameter of TiO2 nanotube was increased from about 20 nm to 110 nm and its length from about 10 nm to 700 nm. In addition, the length of TiO2 nanotube was increased with increasing anodizing time up to 6 h at 20 V. We obtained the longest and the most highly ordered nanotube structure when anodizing Ti in a solution of 0.5 wt% NH4F and 1 M malonic acid at 20 V for 6 h.

Transferable, conductive TiO{sub 2} nanotube membranes for optoelectronics

Energy Technology Data Exchange (ETDEWEB)

Liu, Guohua [School of Energy and Environment, Anhui University of Technology, Maanshan 243002 (China); Department of Micro and Nano Systems Technology, Vestfold University College, Horten 3184 (Norway); Chen, Ting [School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Sun, Yunlan; Chen, Guang [School of Energy and Environment, Anhui University of Technology, Maanshan 243002 (China); Wang, Kaiying, E-mail: Kaiying.Wang@hbv.no [Department of Micro and Nano Systems Technology, Vestfold University College, Horten 3184 (Norway)

2014-08-30

Graphical abstract: An optoelectronic device with vertical architecture offers straight conducting filaments for electron transportation. - Highlights: • Highly porous TiO{sub 2} nanotube membranes are prepared by two-step anodization. • An optoelectronic device is integrated with photocurrent transportation along the nanotube axial. • Straight conducting nano-filaments are beneficial for electron transportation. • Photoconductive performances are demonstrated under front/back-illumination. - Abstract: We report a facile approach for preparing free-standing and crystalline TiO{sub 2} nanotube membranes (TNMs) by taking advantage of differential mechanical stress between two anodic layers. The membrane exhibits visible light transmittance (∼40%) and UV absorption (∼99%) with good flexibility, which is favorable to integrate with substrates in optoelectronics. A sandwich-type device is assembled through stacking the membrane and substrates. The dependence of current-perpendicular-to-membrane vs applied voltage shows a remarkable photoconductive performance for both front and back illumination. The photocurrent value increases ∼2 or 3 orders magnitude under UV light radiation as compared to that in darkness. The photoresponse is arisen from high internal gain caused by hole trapping along the nanotube walls. This work is crucial for understanding intrinsic optical properties of nanostructured membranes.

Crystallization of TiO2 Nanotubes by In Situ Heating TEM

KAUST Repository

Casu, Alberto

2018-01-15

The thermally-induced crystallization of anodically grown TiO2 amorphous nanotubes has been studied so far under ambient pressure conditions by techniques such as differential scanning calorimetry and in situ X-ray diffraction, then looking at the overall response of several thousands of nanotubes in a carpet arrangement. Here we report a study of this phenomenon based on an in situ transmission electron microscopy approach that uses a twofold strategy. First, a group of some tens of TiO2 amorphous nanotubes was heated looking at their electron diffraction pattern change versus temperature, in order to determine both the initial temperature of crystallization and the corresponding crystalline phases. Second, the experiment was repeated on groups of few nanotubes, imaging their structural evolution in the direct space by spherical aberration-corrected high resolution transmission electron microscopy. These studies showed that, differently from what happens under ambient pressure conditions, under the microscope’s high vacuum (p < 10−5 Pa) the crystallization of TiO2 amorphous nanotubes starts from local small seeds of rutile and brookite, which then grow up with the increasing temperature. Besides, the crystallization started at different temperatures, namely 450 and 380 °C, when the in situ heating was performed irradiating the sample with electron beam energy of 120 or 300 keV, respectively. This difference is due to atomic knock-on effects induced by the electron beam with diverse energy.

Band-offsets at BaTiO3/Cu2O heterojunction and enhanced photoelectrochemical response: theory and experiment(Conference Presentation)

Science.gov (United States)

Sharma, Dipika; Satsangi, Vibha R.; Dass Kaura, Sahab; Shrivastav, Rohit; Waghmare, Umesh V.

2016-10-01

Band-offsets at BaTiO3/Cu2O heterojunction and enhanced photoelectrochemical response: theory and experiment Dipika Sharmaa, Vibha R. Satsangib, Rohit Shrivastava, Umesh V. Waghmarec, Sahab Dassa aDepartment of Chemistry, Dayalbagh Educational Institute, Agra-282 110 (India) bDepartment of Physics and Computer Sciences, Dayalbagh Educational Institute, Agra-282 110 (India) cTheoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore-560 064 (India) * Phone: +91-9219695960. Fax: +91-562-2801226. E-mail: drsahabdas@gmail.com. Study on photoelectrochemical activity of pristine BaTiO3, Cu2O and BaTiO3/Cu2O heterojunction has been carried out using DFT based band offsets and charge carriers effective mass calculations and their experimental verification. The results of DFT calculations show that BaTiO3 and Cu2O have staggered type band alignment after the heterojunction formation and high mobility of electrons in Cu2O as compared to the electrons in BaTiO3. Staggered type band edges alignment and high mobility of electrons and holes improved the separation of photo-generated charge carriers in BaTiO3/Cu2O heterojunction. To validate the theoretical results experiments were carried out on pristine BaTiO3, Cu2O and BaTiO3/Cu2O heterojunction with varying thickness of Cu2O. All samples were characterized by X- Ray Diffractometer, SEM and UV-Vis spectrometry. Nanostructured thin films of pristine BaTiO3, Cu2O and BaTiO3/Cu2O heterojunction were used as photoelectrode in the photoelectrochemical cell for water splitting reaction. Maximum photocurrent density of 1.44 mA/cm2 at 0.90 V/SCE was exhibited by 442 nm thick BaTiO3/Cu2O heterojunction photoelectrode Increased photocurrent density and enhanced photoconversion efficiency, exhibited by the heterojunction may be attributed to improved conductivity and enhanced separation of the photogenerated carriers at the BaTiO3/Cu2O interface. The experimental results and first

A novel drug delivery of 5-fluorouracil device based on TiO{sub 2}/ZnS nanotubes

Energy Technology Data Exchange (ETDEWEB)

Mendonça Faria, Henrique Antonio, E-mail: henrique.fisica@ifsc.usp.br [Institute of Physics and Chemistry, Federal University of Itajubá (UNIFEI), Av. BPS, 1303, Pinheirinho, Itajubá, MG, PO Box 50, CEP: 37500-903 (Brazil); Nanomedicine and Nanotoxicology Laboratory, São Carlos Institute of Physics, University of São Paulo. Av. Trabalhador São-carlense, 400, Arnold Schimidt, São Carlos, SP CEP: 13566-590 (Brazil); Alencar de Queiroz, Alvaro Antonio, E-mail: alencar@unifei.edu.br [Institute of Physics and Chemistry, Federal University of Itajubá (UNIFEI), Av. BPS, 1303, Pinheirinho, Itajubá, MG, PO Box 50, CEP: 37500-903 (Brazil)

2015-11-01

The structural and electronic properties of titanium oxide nanotubes (TiO{sub 2}) have attracted considerable attention for the development of therapeutic devices and imaging probes for nanomedicine. However, the fluorescence response of TiO{sub 2} has typically been within ultraviolet spectrum. In this study, the surface modification of TiO{sub 2} nanotubes with ZnS quantum dots was found to produce a red shift in the ultra violet emission band. The TiO{sub 2} nanotubes used in this work were obtained by sol–gel template synthesis. The ZnS quantum dots were deposited onto TiO{sub 2} nanotube surface by a micelle-template inducing reaction. The structure and morphology of the resulting hybrid TiO{sub 2}/ZnS nanotubes were investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction techniques. According to the results of fluorescence spectroscopy, pure TiO{sub 2} nanotubes exhibited a high emission at 380 nm (3.26 eV), whereas TiO{sub 2}/ZnS exhibited an emission at 410 nm (3.02 eV). The TiO{sub 2}/ZnS nanotubes demonstrated good bio-imaging ability on sycamore cultured plant cells. The biocompatibility against mammalian cells (Chinese Hamster Ovarian Cells—CHO) suggesting that TiO{sub 2}/ZnS may also have suitable optical properties for use as biological markers in diagnostic medicine. The drug release characteristic of TiO{sub 2}/ZnS nanotubes was explored using 5-fluorouracil (5-FU), an anticancer drug used in photodynamic therapy. The results show that the TiO{sub 2}/ZnS nanotubes are a promising candidate for anticancer drug delivery systems. - Highlights: • TiO{sub 2}/ZnS nanotubes showed a redshift in fluorescence spectrum. • Cytotoxicity against mammalian cells revealed biocompatibility of the nanotubes. • TiO{sub 2}/ZnS proved an efficient delivery system for anti-tumor 5-fluorouracil.

Efficient photocatalytic removal of nitric oxide with hydrothermal synthesized Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes

Energy Technology Data Exchange (ETDEWEB)

Ai, Zhihui, E-mail: jennifer.ai@mail.ccnu.edu.cn; Lu, Gang; Lee, Shuncheng

2014-11-15

Highlights: • Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes were prepared via a facile hydrothermal route. • The Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes exhibited superior photocatalytic performances for the removal of nitric oxide. • The Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes show potential for indoor and outdoor air purification. - Abstract: In this study, Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes were synthesized with a facile hydrothermal method using TiO{sub 2} P25 (Degussa) and bismuth citrate (BiC{sub 5}H{sub 6}O{sub 7}) as precursors in concentrated NaOH and ammonia alkali solution. The samples were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The as-prepared Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes exhibited superior activity for photocatalytic removal of gaseous nitric oxide (NO) over TiO{sub 2} P25 (Degussa) under simulated solar-light irradiation, the NO removal rate can reach as high as ca. 200 ppb·min{sup −1} over the Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes in a continuous reactor with an initial NO concentration of 400 ppb. The intrinsic hollow-nanotube structure of the Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} photocatalysts contributes to its superior activity under simulated solar light. This work provides a facile route to prepare Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes and suggests that the Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes are ideal candidates for efficient removal of nitric oxide in indoor/outdoor air.

Application of nitrogen-doped TiO{sub 2} nano-tubes in dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

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

2017-03-31

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

Interplay of dopants and defects in making Cu doped TiO{sub 2} nanoparticle a ferromagnetic semiconductor

Energy Technology Data Exchange (ETDEWEB)

Choudhury, Biswajit, E-mail: biswa.tezu@gmail.com [Department of Physics, Tezpur University, Napaam 784028, Assam (India); Choudhury, Amarjyoti [Department of Physics, Tezpur University, Napaam 784028, Assam (India); Borah, Debajit [Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam (India)

2015-10-15

Here we have studied the role of oxygen defects and Cu dopants on ferromagnetism in Cu doped TiO{sub 2} nanoparticles with nominal Cu concentration of 2%, 4% and 6 mol%. Electron paramagnetic resonance (EPR) spectra analysis reveals the presence of Cu{sup 2+} in the distorted octahedral coordination of TiO{sub 2}. Cu d-states undergo strong p-d coupling with the valence band O 2p state of TiO{sub 2} resulting the extended absorption hump in the visible region. Photoluminescence results reveal the presence of oxygen defect related emission peaks in Cu doped TiO{sub 2}. Room temperature ferromagnetism is observed in all the Cu doped TiO{sub 2} nanoparticles. Saturation magnetization is the highest at 4 mol% and then there is a decrease in magnetization at 6 mol%. Ferromagnetism completely disappears on calcinations of 4% Cu doped TiO{sub 2} in air at 450 °C for 8 h. It is speculated that both oxygen vacancies and Cu d-states are involved in the room temperature ferromagnetism. Spin polarization occurs by the formation of bound magnetic polaron between electrons in Cu{sup 2+}d-states and the unpaired spins in oxygen vacancies. Presence of Cu{sup 2+}-Cu{sup 2+}d-d exchange interaction and Cu{sup 2+}-O{sup 2−}-Cu{sup 2+} antiferromagnetic superexchange interactions might have resulted in the reduction in magnetization at 6 mol% Cu. - Graphical abstract: Ferromagnetism in Cu doped TiO{sub 2} requires presence of both Cu dopant and oxygen vacancies. - Highlights: • Cu doped TiO{sub 2} nanoparticle displays room temperature ferromagnetism. • Ferromagnetism requires presence of both Cu and oxygen vacancies. • Antiferromagnetic interaction persists at high Cu dopant concentration. • Paramagnetism appears on air annealing of the doped system for longer period.

Room temperature deposition of amorphous p-type CuFeO2 and ...

Indian Academy of Sciences (India)

fabrication of CuFeO2/n-Si heterojunction by RF sputtering method. TAO ZHU1 ... Transparent conducting amorphous p-type CuFeO2 (CFO) thin film was prepared by radio-frequency ... Delafossite oxides CuMO2 (M is trivalent cation, such as.

Synthesis and characterization of Ag-doped TiO2 nanotubes on Ti-6Al-4V and Ti-6Al-7Nb alloy

Science.gov (United States)

Ulfah, Ika Maria; Bachtiar, Boy M.; Murnandityas, Arnita Rut; Slamet

2018-05-01

The present paper is focused on comparative behavior of nanotubes growth on Ti-6Al-4V and Ti-6Al-7Nb alloy using electrochemical anodization method. These alloys were anodized in electrolytes solution containing glycerol, water and 0.5wt.% of NH4F. Silver-doped TiO2 nanotubes were synthesized using photo-assisted deposition (PAD) at various Ag loading concentration in 0.05 M, 0.10 M, and 0.15 M. The phase composition and morphological characteristics were investigated by XRD and FESEM/EDX, respectively. The surface wettability was measured by contact angle meter. The results showed that TiO2 nanotubes can be grown on these surface alloys. XRD profiles revealed crystal formation of anatase, rutile and Ag on these surface alloys. According to FESEM images, the average nanotube diameter of Ti-6Al-4V alloy and Ti-6Al-7Nb alloy are 134 nm and 120 nm, respectively. EDX-Mapping analysis showed that Ag desposited over surface of TiO2 nanotubes. The surface wettability indicated hydrophilicity properties on Ti-4Al-4V alloy and Ti-6Al-7Nb alloy surface. This study may contribute to the development of silver-doped TiO2 nanotubes on Ti-6Al-4V alloy and Ti-6Al-7Nb alloy can be considered in various photocatalytic applications such as biomedical devicesdue to photocatalytic mechanism and antibacterial ability.

Interface feature characterization and Schottky interfacial layer confirmation of TiO{sub 2} nanotube array film

Energy Technology Data Exchange (ETDEWEB)

Li, Hongchao [State Key Laboratory of Powder Metallurgy, Central South University, 410083 Changsha (China); Chongyi Zhangyuan Tungsten Industry Corporation Limited, 341300 Ganzhou (China); Tang, Ningxin; Yang, Hongzhi; Leng, Xian [State Key Laboratory of Powder Metallurgy, Central South University, 410083 Changsha (China); Zou, Jianpeng, E-mail: zoujp@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, 410083 Changsha (China)

2015-11-15

Highlights: • Interfacial fusion of TiO{sub 2} nanotube film increases with annealing temperature. • Interface bonding force of the film increases with annealing temperature. • We report the forth stage of nanofibers formation in the growing mechanism. • TiO{sub 2} nanotubes grow from Schottky interface layer rather than from Ti substrate. • Schottky interface layer's thickness of 35–45 nm is half the diameter of nanotube. - Abstract: We report here characterization of the interfacial microstructure and properties of titanium dioxide (TiO{sub 2}) nanotube array films fabricated by anodization. Field effect scanning electron microscopy (FESEM), X-ray diffraction (XRD), nanoindentation, atomic force microscopy (AFM), selected area electron diffraction (SAED), and high-resolution transmission electron microscopy (HRTEM) were used to characterize the interface of the film. With increasing annealing temperature from 200 °C to 800 °C, the interfacial fusion between the film and the Ti substrate increased. The phase transformation of the TiO{sub 2} nanotube film from amorphous to anatase to rutile took place gradually; as the phase transformation progressed, the force needed to break the film increased. The growth of TiO{sub 2} nanotube arrays occurs in four stages: barrier layer formation, penetrating micropore formation, regular nanotube formation, and nanofiber formation. The TiO{sub 2} nanotubes grow from the Schottky interface layer rather than from the Ti substrate. The Schottky interface layer's thickness of 35–45 nm was identified as half the diameter of the corresponding nanotube, which shows good agreement to the Schottky interface layer growth model. The TiO{sub 2} nanotube film was amorphous and the Ti substrate was highly crystallized with many dislocation walls.

Low Pt content of carbon supported Pt-Ni-TiO2 nanotube electrocatalysts for direct methanol fuel cell

Energy Technology Data Exchange (ETDEWEB)

Jiang, Q.Z; Wu, X.; Ma, Z.F. [Shanghai Jiao Tong Univ., Shanghai, (China). Dept. of Chemical Engineering

2008-07-01

Interest in titanium oxide (TiO2) nanomaterial is growing due to their special characteristics for optics, catalysis, and photoelectricity conversion. In this study, the anatase/rutile crystalline of TiO2 nanoparticles was synthesized by co-deposition. TiO2 nanotubes were then obtained by microwave irradiations. This paper described the mechanism to fabricate TiO2 nanotubes. The conditions for preparing TiO2 nanotubes by microwave irradiation were optimized. Electrocatalysts were then prepared on the basis of the synthesized TiO2 nanotube. Their performances were investigated by the electro-oxidation of methanol. When Pt electrocatalysts were doped with a certain content of TiO2 nanotubes, they had more electrocatalytic activity for methanol electro-oxidation, particularly if the second transition metal, such as Ni, was added into the electrocatalyst. The electrocatalysts contained 5 and 10 wt per cent of Pt and Ni respectively. The 10 wt per cent TiO2 nanotubes showed better activities than any other catalysts for methanol electro-oxidation. According to XRD and TEM results, the size of nanoparticles of Pt became smaller after adding TiO2 nanotubes into the catalysts. It was concluded that here might be some interactions between Pt, Ni, and TiO2 nanotubes.

Improved electrochemical performances of CuO nanotube array prepared via electrodeposition as anode for lithium ion battery

Energy Technology Data Exchange (ETDEWEB)

Xiao, Anguo, E-mail: hixiaoanguo@126.com; Zhou, Shibiao; Zuo, Chenggang; Zhuan, Yongbing; Ding, Xiang

2015-10-15

Graphical abstract: CuO nanotube array electrodes prepared by electrodeposition method exhibit an excellent lithium ion storage ability as anode of Li-ion battery. - Highlights: • CuO nanotube arrays are synthesized by an electrodeposition method. • CuO nanotube shows a high-rate performance. • CuO nanotube shows an excellent cycling performance. - Abstract: We report a facile strategy to prepared CuO nanotube arrays directly grown on Cu plate through the electrodeposition method. The as-prepared CuO nanotubes show a quasi-cylinder nanostructure with internal diameters of ca. ∼100 nm, external diameters of ca. ∼120 nm, and average length of ∼3 μm. As an anode for lithium ion batteries, the electrochemical properties of the CuO nanotube arrays are investigated by cyclic voltammetry (CV) and galvanostatic charge/discharge tests. Due to the unique nanotube nanostructure, the as-prepared CuO electrodes exhibit good rate performance (550 mAh g{sup −1} at 0.1 C and 464 mAh g{sup −1} at 1 C) and cycling performance (581 mAh g{sup −1} at 0.1 C and 538 mAh g{sup −1} at 0.5 C)

Electrochemically Obtained TiO2/CuxOy Nanotube Arrays Presenting a Photocatalytic Response in Processes of Pollutants Degradation and Bacteria Inactivation in Aqueous Phase

Directory of Open Access Journals (Sweden)

Magda Kozak

2018-06-01

Full Text Available TiO2/CuxOy nanotube (NT arrays were synthesized using the anodization method in the presence of ethylene glycol and different parameters applied. The presence, morphology, and chemical character of the obtained structures was characterized using a variety of methods—SEM (scanning electron microscopy, XPS (X-ray photoelectron spectroscopy, XRD (X-ray crystallography, PL (photoluminescence, and EDX (energy-dispersive X-ray spectroscopy. A p-n mixed oxide heterojunction of Ti-Cu was created with a proved response to the visible light range and the stable form that were in contact with Ti. TiO2/CuxOy NTs presented the appearance of both Cu2O (mainly and CuO components influencing the dimensions of the NTs (1.1–1.3 µm. Additionally, changes in voltage have been proven to affect the NTs’ length, which reached a value of 3.5 µm for Ti90Cu10_50V. Degradation of phenol in the aqueous phase was observed in 16% of Ti85Cu15_30V after 1 h of visible light irradiation (λ > 420 nm. Scavenger tests for phenol degradation process in presence of NT samples exposed the responsibility of superoxide radicals for degradation of organic compounds in Vis light region. Inactivation of bacteria strains Escherichia coli (E. coli, Bacillus subtilis (B. subtilis, and Clostridium sp. in presence of obtained TiO2/CuxOy NT photocatalysts, and Vis light has been studied showing a great improvement in inactivation efficiency with a response rate of 97% inactivation for E. coli and 98% for Clostridium sp. in 60 min. Evidently, TEM (transmission electron microscopy images confirmed the bacteria cells’ damage.

Visible-light-driven photoelectrochemical and photocatalytic performances of Cr-doped SrTiO3/TiO2 heterostructured nanotube arrays.

Science.gov (United States)

Jiao, Zhengbo; Chen, Tao; Xiong, Jinyan; Wang, Teng; Lu, Gongxuan; Ye, Jinhua; Bi, Yingpu

2013-01-01

Well-aligned TiO2 nanotube arrays have become of increasing significance because of their unique highly ordered array structure, high specific surface area, unidirectional charge transfer and transportation features. However, their poor visible light utilization as well as the high recombination rate of photoexcited electron-hole pairs greatly limited their practical applications. Herein, we demonstrate the fabrication of visible-light-responsive heterostructured Cr-doped SrTiO3/TiO2 nanotube arrays by a simple hydrothermal method, which facilitate efficient charge separation and thus improve the photoelectrochemical as well as photocatalytic performances.

Plasma-induced synthesis of Pt nanoparticles supported on TiO{sub 2} nanotubes for enhanced methanol electro-oxidation

Energy Technology Data Exchange (ETDEWEB)

Su, Nan [College of Materials Science and Engineering, Nanjing Tech University, Xin-Mo-Fan Road No. 5, 210009, Nanjing, Jiangsu (China); The Synergetic Innovation Center for Advanced Materials, Xin-Mo-Fan Road No. 5, 210009, Nanjing, Jiangsu (China); Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Xin-Mo-Fan Road No. 5, 210009, Nanjing, Jiangsu (China); Hu, Xiulan, E-mail: whoxiulan@163.com [College of Materials Science and Engineering, Nanjing Tech University, Xin-Mo-Fan Road No. 5, 210009, Nanjing, Jiangsu (China); The Synergetic Innovation Center for Advanced Materials, Xin-Mo-Fan Road No. 5, 210009, Nanjing, Jiangsu (China); Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Xin-Mo-Fan Road No. 5, 210009, Nanjing, Jiangsu (China); Zhang, Jianbo; Huang, Huihong; Cheng, Jiexu; Yu, Jinchen; Ge, Chao [College of Materials Science and Engineering, Nanjing Tech University, Xin-Mo-Fan Road No. 5, 210009, Nanjing, Jiangsu (China)

2017-03-31

Highlights: • Pt nanoparticles are synthesized by plasma sputtering in water. • Pt/C/TiO{sub 2} nanotubes shows better mass activity and CO-poisoning tolerance than Pt/C. • TiO{sub 2} nanotubes are more suitable for support materials than TiO{sub 2} small particles. • The metal-support interactions between Pt and TiO{sub 2} nanotubes are detected by XPS. - Abstract: A Pt/C/TiO{sub 2} nanotube composite catalyst was successfully prepared for enhanced methanol electro-oxidation. Pt nanoparticles with a particle size of 2 nm were synthesized by plasma sputtering in water, and anatase TiO{sub 2} nanotubes with an inner diameter of approximately 100 nm were prepared by a simple two-step anodization method and annealing process. Field-emission scanning electron microscopy images indicated that the different morphologies of TiO{sub 2} synthesized on the surface of Ti foils were dependent on the different anodization parameters. The electrochemical performance of Pt/C/TiO{sub 2} catalysts for methanol oxidation showed that TiO{sub 2} nanotubes were more suitable for use as Pt nanoparticle support materials than irregular TiO{sub 2} short nanorods due to their tubular morphology and better electronic conductivity. X-ray photoelectron spectroscopy characterization showed that the binding energies of the Pt 4f of the Pt/C/TiO{sub 2} nanotubes exhibited a slightly positive shift caused by the relatively strong interaction between Pt and the TiO{sub 2} nanotubes, which could mitigate the poisoning of the Pt catalyst by CO{sub ads}, and further enhance the electrocatalytic performance. Thus, the as-obtained Pt/C/TiO{sub 2} nanotubes composites may become a promising catalyst for methanol electro-oxidation.

Plasma-induced synthesis of Pt nanoparticles supported on TiO2 nanotubes for enhanced methanol electro-oxidation

Science.gov (United States)

Su, Nan; Hu, Xiulan; Zhang, Jianbo; Huang, Huihong; Cheng, Jiexu; Yu, Jinchen; Ge, Chao

2017-03-01

A Pt/C/TiO2 nanotube composite catalyst was successfully prepared for enhanced methanol electro-oxidation. Pt nanoparticles with a particle size of 2 nm were synthesized by plasma sputtering in water, and anatase TiO2 nanotubes with an inner diameter of approximately 100 nm were prepared by a simple two-step anodization method and annealing process. Field-emission scanning electron microscopy images indicated that the different morphologies of TiO2 synthesized on the surface of Ti foils were dependent on the different anodization parameters. The electrochemical performance of Pt/C/TiO2 catalysts for methanol oxidation showed that TiO2 nanotubes were more suitable for use as Pt nanoparticle support materials than irregular TiO2 short nanorods due to their tubular morphology and better electronic conductivity. X-ray photoelectron spectroscopy characterization showed that the binding energies of the Pt 4f of the Pt/C/TiO2 nanotubes exhibited a slightly positive shift caused by the relatively strong interaction between Pt and the TiO2 nanotubes, which could mitigate the poisoning of the Pt catalyst by COads, and further enhance the electrocatalytic performance. Thus, the as-obtained Pt/C/TiO2 nanotubes composites may become a promising catalyst for methanol electro-oxidation.

Synthesis of calcium-phosphorous doped TiO2 nanotubes by anodization and reverse polarization: A promising strategy for an efficient biofunctional implant surface

International Nuclear Information System (INIS)

Alves, Sofia A.; Patel, Sweetu B.; Sukotjo, Cortino; Mathew, Mathew T.; Filho, Paulo N.; Celis, Jean-Pierre

2017-01-01

Highlights: • A new surface modification methodology for bio-functionalization of TiO2 NTs is addressed • Bone-like structured TiO2 nanotubular surfaces containing Ca and P were synthesized. • Ca/P-doped TiO2 NTs enhanced adhesion and proliferation of osteoblastic-like cells. • The bio-functionalization granted improved bio-electrochemical stability to TiO2 NTs. - Abstract: The modification of surface features such as nano-morphology/topography and chemistry have been employed in the attempt to design titanium oxide surfaces able to overcome the current dental implants failures. The main goal of this study is the synthesis of bone-like structured titanium dioxide (TiO 2 ) nanotubes enriched with Calcium (Ca) and Phosphorous (P) able to enhance osteoblastic cell functions and, simultaneously, display an improved corrosion behavior. To achieve the main goal, TiO 2 nanotubes were synthetized and doped with Ca and P by means of a novel methodology which relied, firstly, on the synthesis of TiO 2 nanotubes by anodization of titanium in an organic electrolyte followed by reverse polarization and/or anodization, in an aqueous electrolyte. Results show that hydrophilic bone-like structured TiO 2 nanotubes were successfully synthesized presenting a highly ordered nano-morphology characterized by non-uniform diameters. The chemical analysis of such nanotubes confirmed the presence of CaCO 3 , Ca 3 (PO 4 ) 2 , CaHPO 4 and CaO compounds. The nanotube surfaces submitted to reverse polarization, presented an improved cell adhesion and proliferation compared to smooth titanium. Furthermore, these surfaces displayed a significantly lower passive current in artificial saliva, and so, potential to minimize their bio-degradation through corrosion processes. This study addresses a very simple and promising multidisciplinary approach bringing new insights for the development of novel methodologies to improve the outcome of osseointegrated implants.

Magnetic and structural study of Cu-doped TiO2 thin films

International Nuclear Information System (INIS)

Torres, C.E. Rodriguez; Golmar, F.; Cabrera, A.F.; Errico, L.; Navarro, A.M. Mudarra; Renteria, M.; Sanchez, F.H.; Duhalde, S.

2007-01-01

Transparent pure and Cu-doped (2.5, 5 and 10 at.%) anatase TiO 2 thin films were grown by pulsed laser deposition technique on LaAlO 3 substrates. The samples were structurally characterized by X-ray absorption spectroscopy and X-ray diffraction. The magnetic properties were measured using a SQUID. All films have a FM-like behaviour. In the case of the Cu-doped samples, the magnetic cycles are almost independent of the Cu concentration. Cu atoms are forming CuO and/or substituting Ti in TiO 2 . The thermal treatment in air promotes the CuO segregation. Since CuO is antiferromagnetic, the magnetic signals present in the films could be assigned to Cu substitutionally replacing cations in TiO 2

Synthesis of carbon nanotube-TiO2 nanotubular material for reversible hydrogen storage

International Nuclear Information System (INIS)

Mishra, Amrita; Banerjee, Subarna; Mohapatra, Susanta K; Graeve, Olivia A; Misra, Mano

2008-01-01

A material consisting of multi-walled carbon nanotubes (MWCNTs) and larger titania (TiO 2 ) nanotube arrays has been produced and found to be efficient for reversible hydrogen (H 2 ) storage. The TiO 2 nanotube arrays (diameter ∼60 nm and length ∼2-3 μm) are grown on a Ti substrate, and MWCNTs a few μm in length and ∼30-60 nm in diameter are grown inside these TiO 2 nanotubes using chemical vapor deposition with cobalt as a catalyst. The resulting material has been used in H 2 storage experiments based on a volumetric method using the pressure, composition, and temperature relationship of the storage media. This material can store up to 2.5 wt% of H 2 at 77 K under 25 bar with more than 90% reversibility.

Synthesis of carbon nanotube-TiO(2) nanotubular material for reversible hydrogen storage.

Science.gov (United States)

Mishra, Amrita; Banerjee, Subarna; Mohapatra, Susanta K; Graeve, Olivia A; Misra, Mano

2008-11-05

A material consisting of multi-walled carbon nanotubes (MWCNTs) and larger titania (TiO(2)) nanotube arrays has been produced and found to be efficient for reversible hydrogen (H(2)) storage. The TiO(2) nanotube arrays (diameter ∼60 nm and length ∼2-3 µm) are grown on a Ti substrate, and MWCNTs a few µm in length and ∼30-60 nm in diameter are grown inside these TiO(2) nanotubes using chemical vapor deposition with cobalt as a catalyst. The resulting material has been used in H(2) storage experiments based on a volumetric method using the pressure, composition, and temperature relationship of the storage media. This material can store up to 2.5 wt% of H(2) at 77 K under 25 bar with more than 90% reversibility.

Synergistic effects between TiO2 and carbon nanotubes (CNTs) in a TiO2/CNTs system under visible light irradiation.

Science.gov (United States)

Wu, Chung-Hsin; Kuo, Chao-Yin; Chen, Shih-Ting

2013-01-01

This study synthesized a TiO2/carbon nanotubes (CNTs) composite via the sol-gel method. The surface characteristics of the TiO2/CNTs composite were determined by X-ray diffraction, transmission electron microscopy, specific surface area analyser, ultraviolent (UV)-vis spectroscopy, X-ray photoelectron spectroscopy and Raman spectrometer. The photocatalytic activity ofthe TiO2/CNTs composite was evaluated by decolourizing C.I. Reactive Red 2 (RR2) under visible light irradiation. Furthermore, the effects of calcination temperature, pH, RR2 concentration, and the TiO2/CNTs composite dosage on RR2 decolourization were determined simultaneously. The optimal calcination temperature to generate TiO2 and the TiO2/CNTs composite was 673 K, as the percentage of anatase crystallization at this temperature was highest. The specific surface area of the TiO2/CNTs composite and TiO2 were 45 and 42 m2/g, respectively. The band gap of TiO2 and the TiO2/CNTs composite was 2.97 and 2.71 eV by UV-vis measurements, respectively. Experimental data indicate that the Ti-O-C bond formed in the TiO2/CNTs composite. The RR2 decolourization rates can be approximated by pseudo-first-order kinetics; moreover, only the TiO2/CNTs composite had photocatalytic activity under visible light irradiation. At pH 7, the RR2 decolourization rate constant of 0.5, 1 and 2 g/L TiO2/CNTs addition was 0.005, 0.0015, and 0.0047 min(-1), respectively. Decolourization rate increased as pH and the RR2 concentration decreased. The CNTs functioned as electron acceptors, promoting separation of photoinduced electron-hole pairs to retard their recombination; thus, photocatalytic activity of the TiO2/CNTs composite exceeded that of TiO2.

Ultraviolet–Visible photo-response of p-Cu2O/n-ZnO heterojunction prepared on flexible (PET) substrate

International Nuclear Information System (INIS)

Elfadill, Nezar G.; Hashim, M.R.; Saron, K.M.A.; Chahrour, Khaled M.; Qaeed, M.A.; Bououdina, M.

2015-01-01

The deposition of monocrystalline ZnO nanostructures (using different concentration of reaction solution) on Cu 2 O thin film by hydrothermal method is reported. The mechanism of growing different ZnO nanostructures i.e. nanoneedles, nanotubes and nanorods are explained based on the gradient of Zn + species (resulting from precipitation) in reaction solution. The UV-VIS photo-detection properties of the three selected p-Cu 2 O/n-ZnO heterojunctions are studied by illuminated I–V characteristic and the wavelength dependent photo-responsivity properties. The spectral responsivity curves can be divided into three regions (1.9–2.17 eV), (2.2–2.9 eV) and (>3.2 eV) denoted as A, B and C. The regions A and C are assigned for band to band level absorption in Cu 2 O and ZnO respectively, while region C is associated with a combination of two absorption process: part of photons were absorbed by the band to deep level absorption in ZnO and the transmitted photons were absorbed in Cu 2 O. It is found that the heterojunctions with nanotubes exhibit higher responsivity than other nanostructures, which is mainly due to the large surface-to-volume ratio. - Highlights: • Fabrication of p-Cu 2 O/n-ZnO heterojunction on flexible PET substrate. • Synthesis of different ZnO nanostructures i.e. nanoneedles, nanotubes and nanorods. • The UV-VIS photo-detection properties of p-Cu 2 O/n-ZnO heterojunctions

Synthesis of carbon-coated TiO 2 nanotubes for high-power lithium-ion batteries

Science.gov (United States)

Park, Sang-Jun; Kim, Young-Jun; Lee, Hyukjae

Carbon-coated TiO 2 nanotubes are prepared by a simple one-step hydrothermal method with an addition of glucose in the starting powder, and are characterized by morphological analysis and electrochemical measurement. A thin carbon coating on the nanotube surface effectively suppresses severe agglomeration of TiO 2 nanotubes during hydrothermal reaction and post calcination. This action results in better ionic and electronic kinetics when applied to lithium-ion batteries. Consequently, carbon-coated TiO 2 nanotubes deliver a remarkable lithium-ion intercalation/deintercalation performance, such as reversible capacities of 286 and 150 mAh g -1 at 250 and 7500 mA g -1, respectively.

Synthesis, structure, and physicochemical investigations of the new α Cu 0.50TiO(PO 4) oxyphosphate

Science.gov (United States)

Benmokhtar, S.; Belmal, H.; El Jazouli, A.; Chaminade, J. P.; Gravereau, P.; Pechev, S.; Grenier, J. C.; Villeneuve, G.; de Waal, D.

2007-02-01

The room-temperature crystal structure of a new Cu(II) oxyphosphate— α Cu 0.50IITiO(PO 4)—was determined from X-ray single crystals diffraction data, in the monoclinic system, space group P2 1/c. The refinement from 5561 independent reflections lead to the following parameters: a=7.5612(4)Å, b=7.0919(4)Å, c=7.4874(4)Å, β=122.25(1)°, Z=4, with the final R=0.0198, wR=0.0510. The structure of α Cu 0.50IITiO(PO 4) can be described as a TiOPO 4 framework constituted by chains of tilted corner-sharing [TiO 6] octahedra running parallel to the c-axis and cross linked by phosphate [PO 4] tetrahedra, where one-half of octahedral cavities created are occupied by Cu atoms. Ti atoms are displaced from the center of octahedra units in alternating long (2.308 Å) and short (1.722 Å) Ti-O(1) bonds along chains. Such O(1) atoms not linked to P atoms justify the oxyphosphate formulation α Cu 0.50TiO(PO 4). The divalent cations Cu 2+ occupy a Jahn-Teller distorted octahedron sharing two faces with two [TiO 6] octahedra. EPR and optical measurements are in good agreement with structural data. The X-ray diffraction results are supported by Raman and infrared spectroscopy studies that confirmed the existence of the infinite chains -Ti-O-Ti-O-Ti-. α Cu 0.50TiO(PO 4) shows a Curie-Weiss paramagnetic behavior in the temperature range 4-80 K.

Fabrication and photocatalytic activity of high-efficiency visible-light-responsive photocatalyst ZnTe/TiO2 nanotube arrays

International Nuclear Information System (INIS)

Liu Yutang; Zhang Xilin; Liu Ronghua; Yang Renbin; Liu Chengbin; Cai Qingyun

2011-01-01

A new ZnTe modified TiO 2 nanotube (NT) array catalyst was prepared by pulse potential electrodeposition of ZnTe nanoparticles (NPs) onto TiO 2 NT arrays, and its application for photocatalytic degradation of anthracene-9-carboxylic acid (9-AnCOOH) was investigated. The even distribution of ZnTe NPs was well-proportionately grown on the top surface of the TiO 2 NT while without clogging the tube entrances. Compared with the unmodified TiO 2 NT, the ZnTe modified TiO 2 NT (ZnTe/TiO 2 NT) showed significantly enhanced photocatalytic activity towards 9-AnCOOH under simulated solar light. After 70 min of irradiation, 9-AnCOOH was degraded with the removal ratio of 45% on the bare TiO 2 NT, much lower than 80%, 90%, and 100% on the ZnTe/TiO 2 NT with the ZnTe NPs prepared under the pulsed 'on' potentials of -0.8, -1.0, and -2.0 V, respectively. The increased photodegradation efficiency mainly results from the improved photocurrent density as results of enhanced visible-light absorption and decreased hole-electron recombination due to the presence of narrow-band-gap p-type semiconductor ZnTe. -- Graphical abstract: Surface-view SEM images of ZnTe/TiO 2 NT prepared under -2.0 V, and the inset is the corresponding enlarged drawings. Display Omitted Research highlights: → A new method to deposit chalcogenides of transition metals on the TiO 2 nanotubes. → The even distribution of ZnTe nanoparticles was well-proportionedly grown onto TiO 2 NT arrays. → ZnTe/TiO 2 NT showed remarkably increased photocurrent density. → ZnTe/TiO 2 NT showed good photocatalytic performance. → The prepared new catalyst has a promising application in practical systems.

Synthesis of stable TiO2 nanotubes: effect of hydrothermal treatment, acid washing and annealing temperature.

Science.gov (United States)

López Zavala, Miguel Ángel; Lozano Morales, Samuel Alejandro; Ávila-Santos, Manuel

2017-11-01

Effect of hydrothermal treatment, acid washing and annealing temperature on the structure and morphology of TiO 2 nanotubes during the formation process was assessed. X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy analysis were conducted to describe the formation and characterization of the structure and morphology of nanotubes. Hydrothermal treatment of TiO 2 precursor nanoparticles and acid washing are fundamental to form and define the nanotubes structure. Hydrothermal treatment causes a change in the crystallinity of the precursor nanoparticles from anatase phase to a monoclinic phase, which characterizes the TiO 2 nanosheets structure. The acid washing promotes the formation of high purity nanotubes due to Na + is exchanged from the titanate structure to the hydrochloric acid (HCl) solution. The annealing temperature affects the dimensions, structure and the morphology of the nanotubes. Annealing temperatures in the range of 400 °C and 600 °C are optimum to maintain a highly stable tubular morphology of nanotubes. Additionally, nanotubes conserve the physicochemical properties of the precursor Degussa P25 nanoparticles. Temperatures greater than 600 °C alter the morphology of nanotubes from tubular to an irregular structure of nanoparticles, which are bigger than those of the precursor material, i.e., the crystallinity turn from anatase phase to rutile phase inducing the collapse of the nanotubes.

Highly stable palladium-loaded TiO{sub 2} nanotube array electrode for the electrocatalytic hydrodehalogenation of polychlorinated biphenyls

Energy Technology Data Exchange (ETDEWEB)

Cui, Chunyue; Wu, Juan; Xin, Yanjun [Qingdao Agricultural University, Qingdao (China); Han, Yanhe [Beijing Institute of Petrochemical Technology, Beijing (China)

2015-06-15

Palladized TiO{sub 2} nanotube array electrode was prepared for the electrocatalytic hydrodehalogenation (HDH) of 2,4,5-trichlorobiphenyl (2,4,5-PCB). The TiO{sub 2} nanotube array electrode was successfully fabricated by anodic oxidation method, and Pd was loaded onto the TiO{sub 2} nanotubes by electrochemical deposition. The morphology and structure of the nanotube array electrodes with and without Pd catalysts were evaluated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results showed that the diameters and lengths of the TiO{sub 2} nanotubes were 30-50 nm and 200-400 nm, respectively. The particle size of the Pd was about 12 nm. Electrocatalytic HDH of 2,4,5-PCB with the Pd/TiO{sub 2} nanotube array electrode was performed in H-cell reactor. Under a constant potential of -1.0 V, the HDH efficiency of 2,4,5-PCB was 90% and the biphenyl yield was 83% (15% current efficiency) within 180min at the Pd/TiO{sub 2} nanotube array electrode. Compared with the Pd/Ti electrode, the Pd/TiO{sub 2} nanotube array electrode exhibited higher HDH efficiency and stability. Additionally, the effect of the primary HDH factors was also investigated.

Optical properties of TiO2 nanotube arrays fabricated by the electrochemical anodization method

International Nuclear Information System (INIS)

Ly, Ngoc Tai; Nguyen, Van Chien; Dao, Thi Hoa; Hoang To, Le Hong; Pham, Duy Long; Do, Hung Manh; Vu, Dinh Lam; Le, Van Hong

2014-01-01

Perpendicularly self-aligned TiO 2 nanotube samples of size of 3 × 5 cm 2 were fabricated by the electrochemical anodization method using a solution containing NH 4 F. Influences of the technological conditions such as NH 4 F concentration and anodization voltage were studied. It was found that NH 4 F concentration in the solution and anodization voltage significantly affect the diameter and length of a TiO 2 nanotube. The diameter and the length of a TiO 2 nanotube were observed and estimated by using scanning electron microscopy. It has shown that the largest diameter and the longest length of about 80 nm and 20 μm, respectively, were obtained for the sample anodized in a solution containing 0.4% of NH 4 F, under a voltage of 48 V. Photoluminescence spectra excited by laser lights having wavelengths of 325 and 442 nm (having energies higher and lower than the band gap energy of TiO 2 ) was recorded at room temperature for the TiO 2 nanotube arrays. An abnormal luminescence result was observed. It is experimental evidence that the manufactured TiO 2 nanotube array is an expected material for hydrogen splitting from water by photochemical effect under sunlight as well as for the nano solar cells. (paper)

P-type Cu2O/SnO bilayer thin film transistors processed at low temperatures

KAUST Repository

Al-Jawhari, Hala A.

2013-10-09

P-type Cu2O/SnO bilayer thin film transistors (TFTs) with tunable performance were fabricated using room temperature sputtered copper and tin oxides. Using Cu2O film as capping layer on top of a SnO film to control its stoichiometry, we have optimized the performance of the resulting bilayer transistor. A transistor with 10 nm/15 nm Cu2O to SnO thickness ratio (25 nm total thickness) showed the best performance using a maximum process temperature of 170 C. The bilayer transistor exhibited p-type behavior with field-effect mobility, on-to-off current ratio, and threshold voltage of 0.66 cm2 V-1 s-1, 1.5×10 2, and -5.2 V, respectively. The advantages of the bilayer structure relative to single layer transistor are discussed. © 2013 American Chemical Society.

Photo-electrocatalytic activity of TiO2 nanotubes prepared with two-step anodization and treated under UV light irradiation

Directory of Open Access Journals (Sweden)

Mohamad Mohsen Momeni

2016-01-01

Full Text Available To improve the photo-catalytic degradation of salicylic acid, we reported the fabrication of ordered TiO2 nanotube arrays by a simple and effective two-step anodization method and then these TiO2 nanotubes treated in a methanol solution under UV light irradiation. The TiO2 nanotubes prepared in the two-step anodization process showed better photo-catalytic activity than TiO2 nanotubes prepared in one-step anodization process. Also, compared with TiO2 nanotubes without the UV pretreatment, the TiO2 nanotubes pretreated in a methanol solution under UV light irradiation exhibited significant enhancements in both photocurrent and activity. The treated TiO2 nanotubes exhibited a 5-fold enhancement in photocurrent and a 2.5-fold increase in the photo-catalytic degradation of salicylic acid. Also the effect of addition of persulfate and periodate on the photo-catalytic degradation of salicylic acid were investigated. The results showed that the degradation efficiency of salicylic acid increased with increasing persulfate and periodate concentrations. These treated TiO2 nanotubes are promising candidates for practical photochemical reactors.

Fabrication of doped TiO2 nanotube array films with enhanced photo-catalytic activity

Science.gov (United States)

Peighambardoust, Naeimeh-Sadat; Khameneh-asl, Shahin; Khademi, Adib

2018-01-01

In the present work, we investigate the N and Fe-doped TiO2 nanotube array film prepared by treating TiO2 nanotube array film with ammonia solution and anodizing in Fe(NO3)3 solution respectively. This method avoided the use of hazardous ammonia gas, or laborious ion implantation process. N and Fe-doped TiO2 nanotube arrays (TiO2 NTs) were prepared by electrochemical anodization process in 0.5 wt % HF aqueous solution. The anodization was performed at the conditions of 20 V and 20 min, Followed by a wet immersion in NH3.H2O (1M) for N-doping for 2 hr and annealing post-treatment at 450 °C. The morphology and structure of the nanotube films were characterized by field emission scanning electron microscope (FESEM) and EDX. UV-vis. illumination test were done to observe photo-enhanced catalysis. The effect of different annealing temperature on the structure and photo-absorption property of the TiO2-TNTs was investigated. The results showed that N-TNTs nanotubes exhibited higher photocatalytic activity compared whit the Fe-doped and pure TNTs, because doping N promoted the separation of the photogenerated electrons and holes.

Application of hydrothermally produced TiO{sub 2} nanotubes in photocatalytic esterification of oleic acid

Energy Technology Data Exchange (ETDEWEB)

Manique, Márcia Cardoso, E-mail: marciamanique@yahoo.com.br; Silva, Aline Posteral; Alves, Annelise Kopp; Bergmann, Carlos Pérez

2016-04-15

Highlights: • A hydrothermal method was employed to synthesize TiO{sub 2} nanotubes. • TiO{sub 2} nanotubes were studied for photocatalytic esterification of oleic acid. • Optimum conditions were obtained at a concentration of 15% (w/w) and a molar ratio 3:1 (methanol:oleic acid). • The greater number of hydroxyl groups may have contributed to a low yield of ester versus P25. - Abstract: This study investigated the use of TiO{sub 2} nanotubes (TNTs) as photocatalysts in the esterification of fatty acids for biodiesel production. The TNTs were synthesized via a hydrothermal route and evaluated for their crystallinity, morphology, surface area and photocatalytic activity compared with a TiO{sub 2} P25 standard. Optimum photocatalytic conditions were obtained using a 15% concentration of catalyst (w/w) and a 3:1 molar ratio of methanol to oleic acid. The highest yield of methyl oleate obtained was 86.0% when P25 was used as a photocatalyst. The lowest band gap energy was obtained with the TNT sample synthesized at 110 °C for 48 h (E{sub g} = 3.08 eV), which also exhibited the highest rate of oleic acid esterification (59.3%) among all the investigated TNTs. We also observed that, in addition to the band gap, other factors such as the crystalline phase of the TNTs and their surface area were important in photocatalytic performance.

Ternary composite of TiO2 nanotubes/Ti plates modified by g-C3N4 and SnO2 with enhanced photocatalytic activity for enhancing antibacterial and photocatalytic activity.

Science.gov (United States)

Faraji, Masoud; Mohaghegh, Neda; Abedini, Amir

2018-01-01

A series of g-C 3 N 4 -SnO 2 /TiO 2 nanotubes/Ti plates were fabricated via simple dipping of TiO 2 nanotubes/Ti in a solution containing SnCl 2 and g-C 3 N 4 nanosheets and finally annealing of the plates. Synthesized plates were characterized by various techniques. The SEM analysis revealed that the g-C 3 N 4 -SnO 2 nanosheets with high physical stability have been successfully deposited onto the surface of TiO 2 nanotubes/Ti plate. Photocatalytic activity was investigated using two probe chemical reactions: oxidative decomposition of acetic acid and oxidation of 2-propanol under irradiation. Antibacterial activities for Escherichia coli (E. coli) bacteria were also investigated in dark and under UV/Vis illuminations. Detailed characterization and results of photocatalytic and antibacterial activity tests revealed that semiconductor coupling significantly affected the photocatalyst properties synthesized and hence their photocatalytic and antibacterial activities. Modification of TiO 2 nanotubes/Ti plates with g-C 3 N 4 -SnO 2 deposits resulted in enhanced photocatalytic activities in both chemical and microbial systems. The g-C 3 N 4 -SnO 2 /TiO 2 nanotubes/Ti plate exhibited the highest photocatalytic and antibacterial activity, probably due to the heterojunction between g-C 3 N 4 -SnO 2 and TiO 2 nanotubes/Ti in the ternary composite plate and thus lower electron/hole recombination rate. Based on the obtained results, a photocatalytic and an antibacterial mechanism for the degradation of E. coli bacteria and chemical pollutants over g-C 3 N 4 -SnO 2 /TiO 2 nanotubes/Ti plate were proposed and discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Icariin-Loaded TiO2 Nanotubes for Regulation of the Bioactivity of Bone Marrow Cells

Directory of Open Access Journals (Sweden)

Yanli Zhang

2018-01-01

Full Text Available To explore the effects of icariin on the biocompatibility of dental implants, icariin- (ICA- loaded TiO2 nanotubes were fabricated on Ti substrates via anodic oxidation and physical absorption. The surface characteristics of the specimens were monitored by field emission scanning electron microscopy (FE-SEM, X-ray diffractometry (XRD, contact angle measurements (CA, and high-pressure liquid chromatography. Additionally, the activities of bone marrow cells, such as cytoskeletal, proliferative activities, mineralization, and osteogenesis-related gene expression on the substrates were investigated in detail. The characterization results demonstrated that ICA-loaded TiO2 nanotubes were successfully fabricated and the hydrophilicity of these TiO2 nanotubes was significantly higher than that of the pure Ti groups. The results also showed that ICA-loaded TiO2 nanotubes might not have enhanced effects on cell proliferation and ALP expression. However, it seemed to significantly promote differentiation of bone marrow cells, demonstrated by enhancing the formation of mineralized nodule and the upregulation of the gene expression such as OC, BSP, OPN, and COL-1. The results indicated that ICA-loaded TiO2 nanotubes can modulate bioactivity of bone marrow cells, which is promising for potential applications in the orthopedics field.

Electrochemical synthesis of self-organized TiO2 crystalline nanotubes without annealing

Science.gov (United States)

Giorgi, Leonardo; Dikonimos, Theodoros; Giorgi, Rossella; Buonocore, Francesco; Faggio, Giuliana; Messina, Giacomo; Lisi, Nicola

2018-03-01

This work demonstrates that upon anodic polarization in an aqueous fluoride-containing electrolyte, TiO2 nanotube array films can be formed with a well-defined crystalline phase, rather than an amorphous one. The crystalline phase was obtained avoiding any high temperature annealing. We studied the formation of nanotubes in an HF/H2O medium and the development of crystalline grains on the nanotube wall, and we found a facile way to achieve crystalline TiO2 nanotube arrays through a one-step anodization. The crystallinity of the film was influenced by the synthesis parameters, and the optimization of the electrolyte composition and anodization conditions (applied voltage and time) were carried out. For comparison purposes, crystalline anatase TiO2 nanotubes were also prepared by thermal treatment of amorphous nanotubes grown in an organic bath (ethylene glycol/NH4F/H2O). The morphology and the crystallinity of the nanotubes were studied by field emission gun-scanning electron microscopy (FEG-SEM) and Raman spectroscopy, whereas the electrochemical and semiconducting properties were analyzed by means of linear sweep voltammetry, impedance spectroscopy, and Mott-Schottky plots. X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) allowed us to determine the surface composition and the electronic structure of the samples and to correlate them with the electrochemical data. The optimal conditions to achieve a crystalline phase with high donor concentration are defined.

High quantum yield graphene quantum dots decorated TiO_2 nanotubes for enhancing photocatalytic activity

International Nuclear Information System (INIS)

Qu, Ailan; Xie, Haolong; Xu, Xinmei; Zhang, Yangyu; Wen, Shengwu; Cui, Yifan

2016-01-01

Highlights: • High concentration yellow GQDs and TiO_2 nanotubes were achieved by a simple and green method. • High quantum yield GQDs enhanced the photodegradation capacity of TiO_2 nanotube. • The catalytic performance of GQDs/TiO_2 depends on the GQDs loading. • The improved photocatalytic activity of GQDs/TiO_2 was attributed to three aspects. - Abstract: Graphene quantum dots (GQDs) with high quantum yield (about 23.6% at an excitation wavelength of 320 nm) and GQDs/TiO_2 nanotubes (GQDs/TiO_2 NTs) composites were achieved by a simple hydrothermal method at low temperature. Photoluminescence characterization showed that the GQDs exhibited the down-conversion PL features at excitation from 300 to 420 nm and up-conversion photoluminescence in the range of 600–800 nm. The photocatalytic activity of prepared GQDs/TiO_2 NTs composites on the degradation of methyl orange (MO) was significantly enhanced compared with that of pure TiO_2 nanotubes (TiO_2 NTs). For the composites coupling with 1.5%, 2.5% and 3.5% GQDs, the degradation of MO after 20 min irradiation under UV–vis light irradiation (λ = 380–780 nm) were 80.52%, 94.64% and 51.91%, respectively, which are much higher than that of pure TiO_2 NTs (35.41%). It was inferred from the results of characterization that the improved photocatalytic activity of the GQDs/TiO_2 NTs composites was attributed to the synergetic effect of up-conversion properties of the GQDs, enhanced visible light absorption and efficient separation of photogenerated electron-holes of the GQDs/TiO_2 composite.

Room temperature alcohol sensing by oxygen vacancy controlled TiO2 nanotube array

International Nuclear Information System (INIS)

Hazra, A.; Dutta, K.; Bhowmik, B.; Bhattacharyya, P.; Chattopadhyay, P. P.

2014-01-01

Oxygen vacancy (OV) controlled TiO 2 nanotubes, having diameters of 50–70 nm and lengths of 200–250 nm, were synthesized by electrochemical anodization in the mixed electrolyte comprising NH 4 F and ethylene glycol with selective H 2 O content. The structural evolution of TiO 2 nanoforms has been studied by field emission scanning electron microscopy. Variation in the formation of OVs with the variation of the structure of TiO 2 nanoforms has been evaluated by photoluminescence and X-ray photoelectron spectroscopy. The sensor characteristics were correlated to the variation of the amount of induced OVs in the nanotubes. The efficient room temperature sensing achieved by the control of OVs of TiO 2 nanotube array has paved the way for developing fast responding alcohol sensor with corresponding response magnitude of 60.2%, 45.3%, and 36.5% towards methanol, ethanol, and 2-propanol, respectively.

TiO2 nanotubes supported NiW hydrodesulphurization catalysts: Characterization and activity

International Nuclear Information System (INIS)

Palcheva, R.; Dimitrov, L.; Tyuliev, G.; Spojakina, A.; Jiratova, K.

2013-01-01

Highlights: ► NiW catalysts supported on TiO 2 nanotubes, titania and alumina. ► The best results are obtained with NiW/TiO 2 nanotubes in hydrodesulfurization (HDS) of thiophene. ► Active phase is Ni-WO x S y . ► Electronic promotion of W by Ti. - Abstract: High surface area TiO 2 nanotubes (Ti-NT) synthesized by alkali hydrothermal method were used as a support for NiW hydrodesulphurization catalyst. Nickel salt of 12-tungstophosphoric acid – Ni 3/2 PW 12 O 40 was applied as oxide precursor of the active components. The catalyst was characterized by S BET , XRD, UV–vis DRS, Raman spectroscopy, XPS, TPR and HRTEM. The results obtained were compared with those for the NiW catalysts prepared over high surface area titania and alumina supports. A polytungstate phase evidenced by Raman spectroscopy was observed indicating the destruction of the initial heteropolyanion. The catalytic experiments revealed two times higher thiophene conversion on NiW catalyst supported on Ti-NT than those of catalysts supported on alumina and titania. Increased HDS activity of the NiW catalyst supported on Ti-NT could be related to a higher amount of W oxysulfide entities interacting with Ni sulfide particles as consequence of the electronic effects of the Ti-NT observed with XPS analysis.

Highly efficient photoelectrochemical performance of SrTiO{sub 3}/TiO{sub 2} heterojunction nanotube array thin film

Energy Technology Data Exchange (ETDEWEB)

Zhang Yan [Qingdao University, School of Chemistry, Chemical Engineering and Environments (China); Bu Yuyu [Chinese Academy of Sciences, National Engineering Center of Marine Corrosion Protection, Institute of Oceanology (China); Yu Jianqiang, E-mail: yjq@licp.cas.cn; Li Ping [Qingdao University, School of Chemistry, Chemical Engineering and Environments (China)

2013-06-15

SrTiO{sub 3}-TiO{sub 2} heterojunction thin-film nanotube arrays (SNTs, the average inner diameter is about 50 nm) was fabricated via electrochemical anodization followed by a hydrothermal treatment. The photo-to-current conversion properties and the photoelectrochemical performance for cathodic protection of carbon steel in 0.5 M of sodium chloride solution under white light illumination were investigated. The results showed that the highly ordered nanotube arrays could provide very excellent cathodic protection for carbon steel under white light irradiation.

Magnetic and structural study of Cu-doped TiO{sub 2} thin films

Energy Technology Data Exchange (ETDEWEB)

Torres, C.E. Rodriguez [Dpto de Fisica-IFLP, Fac. Cs. Exactas, Universidad Nacional de La Plata-CONICET, CC 67, 1900 La Plata (Argentina)], E-mail: torres@fisica.unlp.edu.ar; Golmar, F. [Laboratorio de Ablacion Laser, Facultad de Ingenieria, Universidad de Buenos Aires, Paseo Colon 850, 1063 Buenos Aires (Argentina); Cabrera, A.F.; Errico, L.; Navarro, A.M. Mudarra; Renteria, M.; Sanchez, F.H. [Dpto de Fisica-IFLP, Fac. Cs. Exactas, Universidad Nacional de La Plata-CONICET, CC 67, 1900 La Plata (Argentina); Duhalde, S. [Laboratorio de Ablacion Laser, Facultad de Ingenieria, Universidad de Buenos Aires, Paseo Colon 850, 1063 Buenos Aires (Argentina)

2007-10-31

Transparent pure and Cu-doped (2.5, 5 and 10 at.%) anatase TiO{sub 2} thin films were grown by pulsed laser deposition technique on LaAlO{sub 3} substrates. The samples were structurally characterized by X-ray absorption spectroscopy and X-ray diffraction. The magnetic properties were measured using a SQUID. All films have a FM-like behaviour. In the case of the Cu-doped samples, the magnetic cycles are almost independent of the Cu concentration. Cu atoms are forming CuO and/or substituting Ti in TiO{sub 2}. The thermal treatment in air promotes the CuO segregation. Since CuO is antiferromagnetic, the magnetic signals present in the films could be assigned to Cu substitutionally replacing cations in TiO{sub 2}.

Facile fabrication of CuPp–TiO2 mesoporous composite: An excellent and robust heterostructure photocatalyst for 4-nitrophenol degradation

International Nuclear Information System (INIS)

Yu, Mi-Mi; Wang, Chen; Li, Jun; Yuan, Lin; Sun, Wan-Jun

2015-01-01

Graphical abstract: An excellent and robust mesoporous CuPp–TiO 2 photocatalyst was prepared by the self-assemble of TiO 2 with Copper(II) porphyrin following a solvothermal treatment. The HRTEM images of the CuPp–TiO 2 revealed the CuPp combined with TiO 2 are crystalline, which is heterojunction structure. The special structure improves the photocatalytic activity of the catalyst observably. As shown in a heterojunction-type photocatalytic system, the photogenerated electrons in the CB of the CuPp migrate to the CB of the TiO 2 forming reduction sites, while the photogenerated holes in the VB of TiO 2 move to the VB of CuPp through the heterojunction structure forming oxidation sites. As a result, the photogenerated electrons and holes are spatially isolated, which greatly inhibits their undesirable recombination. The photodegradation of 4-nitrophenol (4-NP) illustrated the prepared CuPp–TiO 2 has superior photocatalytic activity and wonderful cycling performance with the photocatalytic efficiency of 86.69% even after six cycles. - Highlights: • A novel mesoporous photocatalyst CuPp–TiO 2 with large surface area was prepared. • The CuPp–TiO 2 was obtained by self-assembly following a solvothermal treatment. • There exists heterojunction structure in CuPp–TiO 2 . • The CuPp–TiO 2 exhibits outstanding photocatalytic activity and stability. - Abstract: An excellent mesoporous CuPp–TiO 2 photocatalyst was prepared by the self-assemble of TiO 2 with metalloporphyrin-copper(II) following a solvothermal treatment. The c-CuPp–TiO 2 was obtained by calcinating CuPp–TiO 2 at 450 °C to investigate the effect of CuPp on photocatalytic activity. The SEM images indicate that CuPp–TiO 2 is microspheres with mean diameter of 29.01 nm. The TEM images reveal that there exists the heterojunction structure in CuPp–TiO 2 , which improved catalytic activity of CuPp–TiO 2 obviously. Additionally, N 2 adsorption–desorption isotherm curves show high

Photoelectrolysis of water using heterostructural composite of TiO2 nanotubes and nanoparticles

International Nuclear Information System (INIS)

Das, Prajna P; Mohapatra, Susanta K; Misra, Mano

2008-01-01

Efficient photoelectrolysis of water to generate hydrogen (H 2 ) can be carried out by designing photocatalysts with good absorption as well as charge transport properties. One dimensional (1D), self-organized titania (TiO 2 ) nanotubes are known to have excellent charge transport properties and TiO 2 nanoparticles (NPs) are good for better photon absorption. This paper describes the synthesis of a composite photocatalyst combining the above two properties of TiO 2 nanocomposites with different morphologies. TiO 2 NPs (5-9 nm nanocrystals form 500-700 nm clusters) have been synthesized from TiCl 4 precursor on TiO 2 nanotubular arrays (∼80 nm diameter and ∼550 nm length) synthesized by the sonoelectrochemical anodization method. This TiO 2 nanotube-nanoparticle composite photoanode has enabled obtaining of enhanced photocurrent density (2.2 mA cm -2 ) as compared with NTs (0.9 mA cm -2 ) and NPs (0.65 mA cm -2 ) alone.

Structure and dye-sensitized solar cell application of TiO2 nanotube arrays fabricated by the anodic oxidation method

Science.gov (United States)

Ok, Seon-Yeong; Cho, Kwon-Koo; Kim, Ki-Won; Ryu, Kwang-Sun

2010-05-01

Well-ordered TiO2 nanotube arrays were fabricated by the potentiostatic anodic oxidation method using pure Ti foil as a working electrode and ethylene glycol solution as an electrolyte with the small addition of NH4F and H2O. The influence of anodization temperature and time on the morphology and formation of TiO2 nanotube arrays was examined. The TiO2 nanotube arrays were applied as a photoelectrode to dye-sensitized solar cells. Regardless of anodizing temperature and time, the average diameter and wall thickness of TiO2 nanotube arrays show a similar value, whereas the length increases with decreasing reaction temperature. The conversion efficiency is very low, which is due to a morphology breaking of the TiO2 nanotube arrays in the manufacturing process of a photoelectrode.

Self-organized TiO{sub 2} nanotubes in mixed organic-inorganic electrolytes and their photoelectrochemical performance

Energy Technology Data Exchange (ETDEWEB)

Lai Yuekun [State Key Laboratory for Physical Chemistry of Solid Surfaces, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Zhuang Huifang; Sun Lan [State Key Laboratory for Physical Chemistry of Solid Surfaces, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Chen Zhong [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Lin Changjian [State Key Laboratory for Physical Chemistry of Solid Surfaces, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China)], E-mail: cjlin@xmu.edu.cn

2009-11-01

The formation of self-organized TiO{sub 2} nanotube array films by electrochemical anodizing titanium foils was investigated in a developed organic-inorganic mixed electrolyte. It was found that the structure and morphology of the TiO{sub 2} nanotube layer were greatly dependent upon the electrolyte composition, anodizing potential and time. Under the optimized electrolyte composition and electrochemical conditions, a controllable, well-ordered TiO{sub 2} nanotube array layer could be fabricated in a short time. The diameters of the as-prepared TiO{sub 2} nanotubes could be adjusted from 20 to 150 nm, and the thickness could be adjusted from a few hundred nanometers to several micrometers. The photoresponse and the photocatalytic activity of the highly ordered TiO{sub 2} nanotube array films were also examined. The nanotube array film with a thickness of about 2.5 {mu}m had the highest incident photon to photocurrent conversion efficiency (IPCE) (34.3%) at the 350 nm wavelength, and had better charge transfer ability under UV light illumination. The photocatalytic experimental results indicated that the 450 deg. C annealing samples have the highest photodegradation efficiency for methyl orange pollutant.

Photocatalytic properties and selective antimicrobial activity of TiO2(Eu)/CuO nanocomposite

Science.gov (United States)

Michal, Robert; Dworniczek, Ewa; Caplovicova, Maria; Monfort, Olivier; Lianos, Panagiotis; Caplovic, Lubomir; Plesch, Gustav

2016-05-01

TiO2(Eu)/CuO nanocomposites were prepared by precipitation method. The anatase nanocrystallites with a size of 26 nm exhibited well crystallized and characteristical dipyramidal morphology and {1 0 1} and {0 0 1} faceting. Transmission electron microscopy photographs with atomic resolution showed that the Eu(III) dopants were bounded on surface of titania. In the composites, the CuO nanocrystals exhibiting a monoclinic tenorite structure with a size in the range from 2 to 5 nm were grafted to the surface of titania. The influence of copper(II) oxide led to distinct selectivity in the photocatalytic and antimicrobial properties of the investigated TiO2(Eu)/CuO nanocomposites. While the presence of CuO nanocrystals strongly increased the photocatalytic production of hydrogen by ethanol reforming, it decreased the activity in photoinduced total mineralization of phenol comparing with non-modified TiO2(Eu). In investigated TiO2(Eu)/CuO powders, the photoinduced antimicrobial activity against membranes of Enterococcus species was influenced by the selective binding of CuO to the surface of the microorganism leading to distinct selectivity in their action. The activity against Enterococcus faecalis was higher than against Enterococcus faecium.

Photocatalytic properties and selective antimicrobial activity of TiO2(Eu)/CuO nanocomposite

International Nuclear Information System (INIS)

Michal, Robert; Dworniczek, Ewa; Caplovicova, Maria; Monfort, Olivier; Lianos, Panagiotis; Caplovic, Lubomir; Plesch, Gustav

2016-01-01

Highlights: • Nanocomposites composed of Eu-doped anatase grafted with CuO. • Increase in photocatalytic hydrogen production due to CuO acting as electrons sink. • CuO in composites decreasing the photoinduced total mineralization of phenol. • Selective photoinduced antimicrobial activity against Enterococcus species. - Abstract: TiO 2 (Eu)/CuO nanocomposites were prepared by precipitation method. The anatase nanocrystallites with a size of 26 nm exhibited well crystallized and characteristical dipyramidal morphology and {1 0 1} and {0 0 1} faceting. Transmission electron microscopy photographs with atomic resolution showed that the Eu(III) dopants were bounded on surface of titania. In the composites, the CuO nanocrystals exhibiting a monoclinic tenorite structure with a size in the range from 2 to 5 nm were grafted to the surface of titania. The influence of copper(II) oxide led to distinct selectivity in the photocatalytic and antimicrobial properties of the investigated TiO 2 (Eu)/CuO nanocomposites. While the presence of CuO nanocrystals strongly increased the photocatalytic production of hydrogen by ethanol reforming, it decreased the activity in photoinduced total mineralization of phenol comparing with non-modified TiO 2 (Eu). In investigated TiO 2 (Eu)/CuO powders, the photoinduced antimicrobial activity against membranes of Enterococcus species was influenced by the selective binding of CuO to the surface of the microorganism leading to distinct selectivity in their action. The activity against Enterococcus faecalis was higher than against Enterococcus faecium.

Bacterial adhesion and inactivation on Ag decorated TiO2-nanotubes under visible light: Effect of the nanotubes geometry on the photocatalytic activity.

Science.gov (United States)

Hajjaji, A; Elabidi, M; Trabelsi, K; Assadi, A A; Bessais, B; Rtimi, S

2018-06-05

This study investigates the effect of the diameter of TiO 2 nanotubes and silver decorated nanotubes on optical properties and photocatalytic inactivation of Escherichia coli under visible light. The TiO 2 nanotubes (TiO 2 -NTs) were prepared using the electrochemical method varying the anodization potential starting from 20 V until 70 V. The Ag nanoparticles were carried out using the photoreduction process under the same experimental conditions. The diameter size was determined using the scanning electronic microscopy (SEM). TiO 2 -NTs diameter reached ∼100 nm at 70 V. Transmission electronic microscopy (TEM) imaging confirmed the TiO 2 -NTs surface decoration by silver nanoparticles. The Ag-NPs average size was found to be equal to 8 nm. The X-Ray diffraction (XRD) analysis confirm that all TiO 2 -NTs crystallize in the anatase phases regardless the used anodization potential. The decrease of the photoluminescence (PL) intensity of Ag NPs decorated TiO 2 -NTs indicates the decrease of the specific area when the nanotubes diameter increases. The UV-vis absorbance show that the absorption edges was bleu shifted with the increasing of nanotubes diameter, which can be explained by the increase of the crystallites average size. The bacterial adhesion and inactivation tests were carried in the dark and under light. Bacteria were seen to adhere on TiO 2 -NTs in the dark; however, under light the bacteria were killed before they establish a strong contact with the TiO 2 -NTs and Ag/TiO 2 -NTs surfaces. Bacterial inactivation kinetics were faster when the anodizing potential of the NTs-preparation increases. A total bacterial inactivation was obtained on ∼100 nm nanotubes diameter within 90 min. This result was attributed to the enhancement of the TNTs crystallinity leading to reduced surface defects. Redox catalysis was seen to occur under light on the TiO 2 -NTs and Ag/TiO 2 -NTs. the photo-induced antibacterial activity on the AgO/Ag 2 O decorated TiO

Photocatalytic Degradation of Methyl Orange over Metalloporphyrins Supported on TiO2 Degussa P25

Directory of Open Access Journals (Sweden)

Xing-Jiao Huang

2012-01-01

Full Text Available The photocatalytic activity of meso-tetraphenylporphyrins with different metal centers (Fe, Co, Mn and Cu adsorbed on TiO2 (Degussa P25 surface has been investigated by carrying out the photodegradation of methyl orange (MO under visible and ultraviolet light irradiation. The photocatalysts were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, diffuse reflectance UV (DRS-UV-vis and infrared spectra. Copper porphyrin-sensitized TiO2 photocatalyst (CuP-TiO2 showed excellent activity for the photodegradation of MO whether under visible or ultraviolet light irradiation. Natural Bond Orbital (NBO charges analysis showed that methyl orange ion is adsorbed easier by CuP-TiO2 catalyst due to the increase of induced interactions.

Binary Oxide p-n Heterojunction Piezoelectric Nanogenerators with an Electrochemically Deposited High p-Type Cu2O Layer.

Science.gov (United States)

Baek, Seung Ki; Kwak, Sung Soo; Kim, Joo Sung; Kim, Sang Woo; Cho, Hyung Koun

2016-08-31

The high performance of ZnO-based piezoelectric nanogenerators (NGs) has been limited due to the potential screening from intrinsic electron carriers in ZnO. We have demonstrated a novel approach to greatly improve piezoelectric power generation by electrodepositing a high-quality p-type Cu2O layer between the piezoelectric semiconducting film and the metal electrode. The p-n heterojunction using only oxides suppresses the screening effect by forming an intrinsic depletion region, and thus sufficiently enhances the piezoelectric potential, compared to the pristine ZnO piezoelectric NG. Interestingly, a Sb-doped Cu2O layer has high mobility and low surface trap states. Thus, this doped layer is an attractive p-type material to significantly improve piezoelectric performance. Our results revealed that p-n junction NGs consisting of Au/ZnO/Cu2O/indium tin oxide with a Cu2O:Sb (cuprous oxide with a small amount of antimony) layer of sufficient thickness (3 μm) exhibit an extraordinarily high piezoelectric potential of 0.9 V and a maximum output current density of 3.1 μA/cm(2).

TiO2/Cu2O composite based on TiO2 NTPC photoanode for photoelectrochemical (PEC) water splitting under visible light

KAUST Repository

Shi, Le

2015-01-01

in practice of water splitting with pure TiO2 material, one of the most popular semiconductor material used for photoelectrochemical water splitting, is still challenging. One dimensional TiO2 nanotubes is highly desired with its less recombination

Synthesis of calcium-phosphorous doped TiO{sub 2} nanotubes by anodization and reverse polarization: A promising strategy for an efficient biofunctional implant surface

Energy Technology Data Exchange (ETDEWEB)

Alves, Sofia A., E-mail: sofiafonso@msn.com [CMEMS – Center of MicroElectroMechanical Systems, Department of Mechanical Engineering, University of Minho, 4800-058 Guimarães (Portugal); IBTN/US – American Branch of the Institute of Biomaterials, Tribocorrosion and Nanomedicine, UIC College of Dentistry, 60612 Chicago, IL (United States); Patel, Sweetu B. [IBTN/US – American Branch of the Institute of Biomaterials, Tribocorrosion and Nanomedicine, UIC College of Dentistry, 60612 Chicago, IL (United States); Department of Mechanical Engineering, Michigan Technological University, 49931 Houghton, MI (United States); Sukotjo, Cortino [IBTN/US – American Branch of the Institute of Biomaterials, Tribocorrosion and Nanomedicine, UIC College of Dentistry, 60612 Chicago, IL (United States); Departmenmt of Restorative Dentistry, University of Illinois at Chicago, 60612 Chicago, IL (United States); Mathew, Mathew T. [IBTN/US – American Branch of the Institute of Biomaterials, Tribocorrosion and Nanomedicine, UIC College of Dentistry, 60612 Chicago, IL (United States); Department of Orthopedic Surgery, Rush University Medical Center, 60612 Chicago, IL (United States); Department of Biomedical Science, UIC School of Medicine at Rockford, 61107 Rockford, IL (United States); Filho, Paulo N. [IBTN/Br – Brazilian Branch of the Institute of Biomaterials, Tribocorrosion and Nanomedicine, UNESP – Universidade Estadual Paulista, Faculdade de Ciências, 17033-360 Bauru, São Paulo (Brazil); Faculdade de Ciências, Departamento de Física, UNESP - Universidade Estadual Paulista, 17033-360 Bauru, São Paulo (Brazil); Celis, Jean-Pierre [Department of Materials Engineering, KU Leuven, 3001 Leuven (Belgium); and others

2017-03-31

Highlights: • A new surface modification methodology for bio-functionalization of TiO2 NTs is addressed • Bone-like structured TiO2 nanotubular surfaces containing Ca and P were synthesized. • Ca/P-doped TiO2 NTs enhanced adhesion and proliferation of osteoblastic-like cells. • The bio-functionalization granted improved bio-electrochemical stability to TiO2 NTs. - Abstract: The modification of surface features such as nano-morphology/topography and chemistry have been employed in the attempt to design titanium oxide surfaces able to overcome the current dental implants failures. The main goal of this study is the synthesis of bone-like structured titanium dioxide (TiO{sub 2}) nanotubes enriched with Calcium (Ca) and Phosphorous (P) able to enhance osteoblastic cell functions and, simultaneously, display an improved corrosion behavior. To achieve the main goal, TiO{sub 2} nanotubes were synthetized and doped with Ca and P by means of a novel methodology which relied, firstly, on the synthesis of TiO{sub 2} nanotubes by anodization of titanium in an organic electrolyte followed by reverse polarization and/or anodization, in an aqueous electrolyte. Results show that hydrophilic bone-like structured TiO{sub 2} nanotubes were successfully synthesized presenting a highly ordered nano-morphology characterized by non-uniform diameters. The chemical analysis of such nanotubes confirmed the presence of CaCO{sub 3}, Ca{sub 3}(PO{sub 4}){sub 2}, CaHPO{sub 4} and CaO compounds. The nanotube surfaces submitted to reverse polarization, presented an improved cell adhesion and proliferation compared to smooth titanium. Furthermore, these surfaces displayed a significantly lower passive current in artificial saliva, and so, potential to minimize their bio-degradation through corrosion processes. This study addresses a very simple and promising multidisciplinary approach bringing new insights for the development of novel methodologies to improve the outcome of osseointegrated

Electronic structures of the YBa2Cu3O7-x surface and its modification by sputtering and adatoms of Ti and Cu

Science.gov (United States)

Meyer, H. M., III; Hill, D. M.; Wagener, T. J.; Gao, Y.; Weaver, J. H.; Capone, D. W., II; Goretta, K. C.

1988-10-01

We present x-ray and inverse photoemission results for fractured surfaces of YBa2Cu3O6.9 before and after surface modification by Ar ion bombardment and the deposition of adatoms of Ti and Cu. Representative results are compared for samples prepared in three different ways. Two of the sample types exhibit substantial emission from grain-boundary phases because of both intergranular and transgranular fracture; they produce results that are very similar to those presented thus far in the literature. A third type was nearly free of contamination and clearly showed spectral features characteristic of the superconductor. Comparison of these nearly contamination-free valence-band results to those for clean La1.85Sr0.15CuO4 shows remarkably similar x-ray photoemission spectroscopy densities of states, with subtle differences near the Fermi level and at 3 eV. Inverse photoemission results show the top of the Cu-O hybrid orbitals to be 2 eV above EF and the empty states of Y and Ba at higher energy. Comparison with one-electron densities of states shows reasonable agreement, but there are large differences within the set of calculated results, and it is unclear from the valence bands alone how to account for final-state Cu d-d Coulomb correlation effects (satellite features show these effects very clearly). Argon sputtering for both types of samples shows destruction of the superconductor, with differences that can be related to sample surface quality. The deposition of adatoms of Ti and Cu results in reaction associated with oxygen withdrawal from the near-surface region. Studies of the Cu 2p3/2 line shape show that the deposition of as little as ~1 monolayer equivalent of Ti or Cu reduces the formal Cu2+ emission within the probed volume (30-50 Å deep). Core-level analysis shows that this chemical reduction of Cu is accompanied by crystal-structure modifications as well. Studies of Cu adatom interactions reveal the progression from Cu2+ to Cu1+ and ultimately, to Cu

Ternary CNTs@TiO2/CoO Nanotube Composites: Improved Anode Materials for High Performance Lithium Ion Batteries

Science.gov (United States)

Madian, Mahmoud; Ummethala, Raghunandan; Abo El Naga, Ahmed Osama; Ismail, Nahla; Rümmeli, Mark Hermann; Eychmüller, Alexander; Giebeler, Lars

2017-01-01

TiO2 nanotubes (NTs) synthesized by electrochemical anodization are discussed as very promising anodes for lithium ion batteries, owing to their high structural stability, high surface area, safety, and low production cost. However, their poor electronic conductivity and low Li+ ion diffusivity are the main drawbacks that prevent them from achieving high electrochemical performance. Herein, we report the fabrication of a novel ternary carbon nanotubes (CNTs)@TiO2/CoO nanotubes composite by a two-step synthesis method. The preparation includes an initial anodic fabrication of well-ordered TiO2/CoO NTs from a Ti-Co alloy, followed by growing of CNTs horizontally on the top of the oxide films using a simple spray pyrolysis technique. The unique 1D structure of such a hybrid nanostructure with the inclusion of CNTs demonstrates significantly enhanced areal capacity and rate performances compared to pure TiO2 and TiO2/CoO NTs, without CNTs tested under identical conditions. The findings reveal that CNTs provide a highly conductive network that improves Li+ ion diffusivity, promoting a strongly favored lithium insertion into the TiO2/CoO NT framework, and hence resulting in high capacity and an extremely reproducible high rate capability. PMID:28773032

Ternary CNTs@TiO2/CoO Nanotube Composites: Improved Anode Materials for High Performance Lithium Ion Batteries

Directory of Open Access Journals (Sweden)

Mahmoud Madian

2017-06-01

Full Text Available TiO2 nanotubes (NTs synthesized by electrochemical anodization are discussed as very promising anodes for lithium ion batteries, owing to their high structural stability, high surface area, safety, and low production cost. However, their poor electronic conductivity and low Li+ ion diffusivity are the main drawbacks that prevent them from achieving high electrochemical performance. Herein, we report the fabrication of a novel ternary carbon nanotubes (CNTs@TiO2/CoO nanotubes composite by a two-step synthesis method. The preparation includes an initial anodic fabrication of well-ordered TiO2/CoO NTs from a Ti-Co alloy, followed by growing of CNTs horizontally on the top of the oxide films using a simple spray pyrolysis technique. The unique 1D structure of such a hybrid nanostructure with the inclusion of CNTs demonstrates significantly enhanced areal capacity and rate performances compared to pure TiO2 and TiO2/CoO NTs, without CNTs tested under identical conditions. The findings reveal that CNTs provide a highly conductive network that improves Li+ ion diffusivity, promoting a strongly favored lithium insertion into the TiO2/CoO NT framework, and hence resulting in high capacity and an extremely reproducible high rate capability.

Dopant concentration dependent magnetism of Cu-doped TiO{sub 2} nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Anitha, B.; Khadar, M. Abdul, E-mail: mabdulkhadar@rediffmail.com [University of Kerala, Centre for Nanoscience and Nanotechnology (India)

2016-06-15

Undoped and Cu-doped nanocrystals of TiO{sub 2} having the size range of 8–11 nm were synthesized by peroxide gel method. XRD analysis using Rietveld refinement confirmed anatase phase with a small percentage of rutile content for undoped TiO{sub 2} nanocrystals while a pure anatase phase with preferential growth along [004] direction was observed for nanocrystals of Cu-doped TiO{sub 2}. Variation in the intensity ratios of the XRD peaks of the doped samples compared to that of the undoped sample offered an evidence for the substitutional incorporation of Cu ions in the TiO{sub 2} lattice. The preferential growth of the nanocrystals along the [004] direction was verified using HRTEM analysis. Cu doping extended the optical absorption edge of TiO{sub 2} nanocrystals to the visible spectral region and caused a blue shift and broadening of the E{sub g} (1) Raman active mode of anatase TiO{sub 2}. Undoped TiO{sub 2} sample showed a weak ferromagnetism superimposed on a diamagnetic background while Cu-doped TiO{sub 2} samples exhibited a weak ferromagnetism in the low-field region with a paramagnetic component in the high-field region. The magnetic moment exhibited by the doped samples is interpreted as the resultant of a weak ferromagnetic moment in the low-field region arising from the presence of defects near the surface of TiO{sub 2} nanoparticles or from the interaction of the substituted Cu ions with the oxygen vacancies, and the paramagnetic contribution from the increased Cu dopant concentration near the surface of the particles arising from self-purification mechanism.

The novel transparent sputtered p-type CuO thin films and Ag/p-CuO/n-Si Schottky diode applications

Directory of Open Access Journals (Sweden)

A. Tombak

2015-01-01

Full Text Available In the current paper, the physical properties and microelectronic parameters of direct current (DC sputtered p-type CuO film and diode have been investigated. The film of CuO as oxide and p-type semiconductor is grown onto glass and n-Si substrates by reactive DC sputtering at 250 °C. After deposition, a post-annealing procedure is applied at various temperatures in ambient. Through this research, several parameters are determined such structural, optical and electrical magnitudes. The thickness of CuO thin films goes from 122 to 254 nm. A (111-oriented cubic crystal structure is revealed by X-ray analysis. The grain size is roughly depending on the post-annealing temperature, it increases with temperature within the 144–285 nm range. The transmittance reaches 80% simultaneously in visible and infrared bands. The optical band gap is varied between 1.99 and 2.52 eV as a result of annealing temperature while the resistivity and the charge carrier mobility decrease with an increase in temperature from 135 to 14 Ω cm and 0.92 to 0.06 cm2/Vs, respectively. The surface of samples is homogenous, bright dots are visible when temperature reaches the highest value. As a diode, Ag/CuO/n-Si exhibits a non-ideal behavior and the ideality factor is about 3.5. By Norde method, the barrier height and the series resistance are extracted and found to be 0.96 V and 86.6 Ω respectively.

High-performance supercapacitors of Cu-based porous coordination polymer nanowires and the derived porous CuO nanotubes.

Science.gov (United States)

Wu, Meng-Ke; Zhou, Jiao-Jiao; Yi, Fei-Yan; Chen, Chen; Li, Yan-Li; Li, Qin; Tao, Kai; Han, Lei

2017-12-12

Electrode materials for supercapacitors with one-dimensional porous nanostructures, such as nanowires and nanotubes, are very attractive for high-efficiency storage of electrochemical energy. Herein, ultralong Cu-based porous coordination polymer nanowires (copper-l-aspartic acid) were used as the electrode material for supercapacitors, for the first time. The as-prepared material exhibits a high specific capacitance of 367 F g -1 at 0.6 A g -1 and excellent cycling stability (94% retention over 1000 cycles). Moreover, porous CuO nanotubes were successfully fabricated by the thermal decomposition of this nanowire precursor. The CuO nanotube exhibits good electrochemical performance with high rate capacity (77% retention at 12.5 A g -1 ) and long-term stability (96% retention over 1000 cycles). The strategy developed here for the synthesis of porous nanowires and nanotubes can be extended to the construction of other electrode materials for more efficient energy storage.

Single-layer graphene-TiO{sub 2} nanotubes array heterojunction for ultraviolet photodetector application

Energy Technology Data Exchange (ETDEWEB)

Zhang, Deng-Yue [School of Material Sciences and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China); Ge, Cai-Wang [School of Electronic Science and Applied Physics, Hefei University of Technology, Hefei, Anhui 230009 (China); Wang, Jiu-Zhen [School of Material Sciences and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China); Zhang, Teng-Fei [School of Electronic Science and Applied Physics, Hefei University of Technology, Hefei, Anhui 230009 (China); Wu, Yu-Cheng, E-mail: ycwu@hfut.edu.cn [School of Material Sciences and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China); Liang, Feng-Xia, E-mail: fxliang@hfut.edu.cn [School of Material Sciences and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China)

2016-11-30

Highlights: • Heterostructures comprised of a single-layer graphene and TiO{sub 2} nanotube arrays were constructed for ultraviolet detection. • The electrical properties of the fabricated heterostructures were dependent on the annealing atmospheres. • The effect of anodic TiO{sub 2} nanotube length on the performance of the photodetector were investigated. - Abstract: In this work, we reported on the fabrication of a single-layer graphene (SLG)-TiO{sub 2} nanotube arrays (NTs) heterostructures ultraviolet photodetector (UVPD) by transferring chemical vapor deposition derived MLG on the surface of anodic TiO{sub 2}NTs array. Through varying the annealing atmosphere and anodization time in the TiO{sub 2} synthesis procedure, the electronic and optoelectronic properties of the as-fabricated Schottky junction UVPD were studied. It was revealed that the anodic TiO{sub 2}NTs annealed in air showed a better rectifying behavior and was highly sensitive to UV light irradiation. Further investigation found that the device performance of the UVPD can be readily modulated by the anodization time, and the anodic TiO{sub 2}NTs with a medium tube length of 9.6 μm exhibits the highest device performance. These results demonstrated that the present SLG-TiO{sub 2}NTs array hetero-junction UVPD will be highly promising for fabricating high-performance optoelectronic device and system in the future.

Photocatalytic performance of Cu-doped TiO2 nanofibers treated by the hydrothermal synthesis and air-thermal treatment

Science.gov (United States)

Wu, Ming-Chung; Wu, Po-Yeh; Lin, Ting-Han; Lin, Tz-Feng

2018-02-01

Series of transition metal-doped TiO2 (metal/TiO2) is prepared by combining the hydrothermal synthesis and air-thermal treatment without any reduction process. The selected transition metal precursors, including Ag, Au, Co, Cr, Cu, Fe, Ni, Pd, Pt, Y, and Zn, were individually doped into TiO2 nanofibers to evaluate the photocatalytic degradation activity and photocatalytic hydrogen generation. Consider the photocatalytic performance of these synthesized metal/TiO2 under UV-A irradiation, copper doped TiO2 nanofibers (Cu/TiO2 NFs) was chosen for further study due to its extraordinary reactivity. Systematical studies were spread to optimize the doping concentration and the calcination condition for much higher photocatalytic activity Cu/TiO2 NFs. In the photocatalytic degradation test, 0.5 mol%-Cu/TiO2 NFs calcined at 650 °C exhibits the highest activity, which is even higher than commercial TiO2-AEROXIDE® TiO2 P25 under UV-A irradiation. The synthesized 0.5 mol%-Cu/TiO2-650 NFs also have the capability in the photocatalytic hydrogen production. The hydrogen evolution rates are 200 μmol/g·h under UV-A irradiation and 280 μmol/g·h under UV-B irradiation. The density of state calculated by CASTEP for Cu/TiO2 indicates that Cu doping contributes to the states near valence band edge and narrows the band gap. The disclosed process in this study is industrial safe, convenient and cost-effective. We further produce a significant amount of TiO2-based catalysts without any hydrogen reduction treatment.

A simple approach for synthesis of TiO{sub 2} nanotubes with through-hole morphology

Energy Technology Data Exchange (ETDEWEB)

Kant, Krishna; Losic, Dusan [University of South Australia, Ian Wark Research Institute, Mawson lakes, SA (Australia)

2009-07-15

The present work reports a simple approach for fabrication of self-standing titania (TiO{sub 2}) nanotube membranes with through-hole morphology. The method is hydrofluoric acid free and the pore opening of TiO{sub 2}nanotubes is performed by electrochemical thinning of the oxide barrier layer. A reduction of anodization voltage was applied at the end of the anodization process to cause a successful removal of the remaining barrier layer from the TiO{sub 2} nanotubes during their detachment from the underlying titanium substrate. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Self-Assembled TiO2 Nanotube Arrays with U-Shaped Profile by Controlling Anodization Temperature

Directory of Open Access Journals (Sweden)

Jingfei Chen

2010-01-01

Full Text Available TiO2 nanotube arrays with uniform diameter from top to bottom were fabricated. The synthesizing approach is based on the investigation of the influence of electrolyte temperature on the tube diameter. We found that the inner diameter of the tubes increased with the electrolyte temperature. Accordingly, we improved the tube profile from the general V shape to U shape by raising the electrolyte temperature gradually. This is a simple and fast approach to fabricate uniform TiO2 nanotubes in diameter. The improved TiO2 nanotube arrays may show better properties and have broad potential applications.

Facile fabrication of Si-doped TiO2 nanotubes photoanode for enhanced photoelectrochemical hydrogen generation

Science.gov (United States)

Dong, Zhenbiao; Ding, Dongyan; Li, Ting; Ning, Congqin

2018-04-01

Photoelectrochemical (PEC) water splitting based doping modified one dimensional (1D) titanium dioxide (TiO2) nanostructures provide an efficient method for hydrogen generation. Here we first successfully fabricated 1D Si-doped TiO2 (Ti-Si-O) nanotube arrays through anodizing Ti-Si alloys with different Si amount, and reported the PEC properties for water splitting. The Ti-Si-O nanotube arrays fabricated on Ti-5 wt.% Si alloy and annealed at 600 °C possess higher PEC activity, yielding a higher photocurrent density of 0.83 mA/cm2 at 0 V vs. Ag/AgCl. The maximum photoconversion efficiency was 0.54%, which was 2.7 times the photoconversion efficiency of undoped TiO2.

Synthesis of Ag-loaded SrTiO_3/TiO_2 heterostructure nanotube arrays for enhanced photocatalytic performances

International Nuclear Information System (INIS)

Hu, Zijun; Chen, Da; Zhan, Xiaqiang; Wang, Fang; Qin, Laishun; Huang, Yuexiang

2017-01-01

In this work, the effect of loading Ag nanoparticles on the photocatalytic activity of SrTiO_3/TiO_2 nanotube arrays (TNTAs) was investigated. TNTAs were partially transformed to SrTiO_3 through a hydrothermal treatment, which could preserve the tubular structure of TNTAs, and then, Ag nanoparticles were well deposited on the surface of SrTiO_3/TNTAs heterostructure by a chemical reduction process. Compared to the TNTAs sample, the Ag-loaded SrTiO_3/TNTAs sample showed significantly enhanced photocatalytic activities for photodegradation of rhodamine B. The enhanced photocatalytic activity of Ag-loaded SrTiO_3/TNTAs could be attributed to the increased optical absorption as well as the efficient charge transfer and separation of photogenerated electron-hole pairs induced by the SrTiO_3/TNTAs heterojunction and the Schottky barrier between metallic Ag and SrTiO_3/TNTAs. On the basis of the trapping experiments, the possible photocatalytic mechanism was also discussed. (orig.)

Synthesis and enhanced photoelectrocatalytic activity of p–n junction Co3O4/TiO2 nanotube arrays

International Nuclear Information System (INIS)

Dai Gaopeng; Liu Suqin; Liang Ying; Luo Tianxiong

2013-01-01

Highlights: ► Co 3 O 4 /TiO 2 nanotube arrays (NTs) were prepared by an impregnating–deposition–decompostion method treatment. ► Co 3 O 4 /TiO 2 NTs exhibit high photoelectrocatalytic (PEC) activity. ► The high PEC activity was attribute to the formation of p–n junction between Co 3 O 4 and TiO 2 . - Abstract: Co 3 O 4 /TiO 2 nanotube arrays (NTs) were prepared by depositing Co 3 O 4 nanoparticles (NPs) on the tube wall of the self-organized TiO 2 NTs using an impregnating–deposition–decompostion method. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV–vis absorption spectroscopy. The photoelectrocatalytic (PEC) activity is evaluated by degradation of methyl orange (MO) aqueous solution. The prepared Co 3 O 4 /TiO 2 NTs exhibit much higher PEC activity than TiO 2 NTs due to the p–n junction formed between Co 3 O 4 and TiO 2 .

High activity of novel Pd/TiO2 nanotube catalysts for methanol electro-oxidation

International Nuclear Information System (INIS)

Wang Mei; Guo Daojun; Li Hulin

2005-01-01

Electro-oxidation of methanol in sulfuric acid solution was studied using palladium well-dispersed on titanium nanotubes, in relation to methanol oxidation processes in the direct oxidation methanol fuel cell. Pd dispersed on titania nanotubes, which leads to high surface area substrates, showed excellent catalytic activities compared to those of pure Pd and Pd-TiO 2 nanoparticles. TEM results show a narrow distribution of TiO 2 nanoparticles whose particle size is about 10nm, and uniform nano-sized TiO 2 nanotubes with 10nm in diameters are seen from HRTEM . A homogeneous structure in the composite nanomaterials is indicated by XRD analysis. The composite electrode activities were measured by cyclic voltammetry (CV) and at 25 deg. C it was found that 3wt% Pd in titania nanotubes had the best activity for methanol oxidation

Room temperature alcohol sensing by oxygen vacancy controlled TiO{sub 2} nanotube array

Energy Technology Data Exchange (ETDEWEB)

Hazra, A.; Dutta, K.; Bhowmik, B.; Bhattacharyya, P., E-mail: pb-etc-besu@yahoo.com [Nano-Thin Films and Solid State Gas Sensor Devices Laboratory, Department of Electronics and Telecommunication Engineering, Indian Institute of Engineering Science and Technology (IIEST), Shibpur, Howrah (India); Chattopadhyay, P. P. [Department of Metallurgy and Materials Engineering, Indian Institute of Engineering Science and Technology (IIEST), Shibpur, Howrah (India)

2014-08-25

Oxygen vacancy (OV) controlled TiO{sub 2} nanotubes, having diameters of 50–70 nm and lengths of 200–250 nm, were synthesized by electrochemical anodization in the mixed electrolyte comprising NH{sub 4}F and ethylene glycol with selective H{sub 2}O content. The structural evolution of TiO{sub 2} nanoforms has been studied by field emission scanning electron microscopy. Variation in the formation of OVs with the variation of the structure of TiO{sub 2} nanoforms has been evaluated by photoluminescence and X-ray photoelectron spectroscopy. The sensor characteristics were correlated to the variation of the amount of induced OVs in the nanotubes. The efficient room temperature sensing achieved by the control of OVs of TiO{sub 2} nanotube array has paved the way for developing fast responding alcohol sensor with corresponding response magnitude of 60.2%, 45.3%, and 36.5% towards methanol, ethanol, and 2-propanol, respectively.

TiO2 micro-flowers composed of nanotubes and their application to dye-sensitized solar cells

Science.gov (United States)

Kim, Woong-Rae; Park, Hun; Choi, Won-Youl

2014-02-01

TiO2 micro-flowers were made to bloom on Ti foil by the anodic oxidation of Ti-protruding dots with a cylindrical shape. Arrays of the Ti-protruding dots were prepared by photolithography, which consisted of coating the photoresists, attaching a patterned mask, illuminating with UV light, etching the Ti surface by reactive ion etching (RIE), and stripping the photoresist on the Ti foil. The procedure for the blooming of the TiO2 micro-flowers was analyzed by field emission scanning electron microscopy (FESEM) as the anodizing time was increased. Photoelectrodes of dye-sensitized solar cells (DSCs) were fabricated using TiO2 micro-flowers. Bare TiO2 nanotube arrays were used for reference samples. The short-circuit current ( J sc) and the power conversion efficiency of the DSCs based on the TiO2 micro-flowers were 4.340 mA/cm2 and 1.517%, respectively. These values of DSCs based on TiO2 micro-flowers were higher than those of bare samples. The TiO2 micro-flowers had a larger surface area for dye adsorption compared to bare TiO2 nanotube arrays, resulting in improved J sc characteristics. The structure of the TiO2 micro-flowers allowed it to adsorb dyes very effectively, also demonstrating the potential to achieve higher power conversion efficiency levels for DSCs compared to a bare TiO2 nanotube array structure and the conventional TiO2 nanoparticle structure.

Reduction of chromium (VI) on the hetero-system CuBi2O4/TiO2 under solar light

Science.gov (United States)

Lahmar, H.; Benamira, M.; Akika, F. Z.; Trari, M.

2017-11-01

The CuBi2O4/TiO2 heterojunction was tested with success for the photo-catalytic reduction of chromate ions under sunlight. CuBi2O4, prepared by nitrate process, was characterised photo-electrochemically. The oxide is stable against photo corrosion by consumption of holes in presence of oxalic acid. The light absorption promotes electrons in the conduction band of the sensitizer (CuBi2O4) with a very negative potential (-1.74 VSCE) to participate in the exchange of the electron with HCrO4-. The enhanced activity is due to electron injection of activated CuBi2O4 into TiO2-CB (-0.97 VSCE). The band gap of the semiconductor CuBi2O4 is 1.50 eV with a direct optical transition. This compound is a p-type semiconductor with a flat band potential of -0.39 VSCE and activation energy of 0.18 eV. The electrochemical impedance spectroscopy was undertaken to study the semiconductor/electrolyte interfacial phenomena. The photoactivity on the heterojunction is strongly enhanced. A remarkable performance is obtained in less than 4 h for a concentration of 30 mg in (Cr (VI)) at pH ∼ 4 and a dose of 1 mg/mL; a 98% reduction has been obtained. The kinetic of chromate photoreduction is well described by the Langmuir-Hinshelwood model. The chromate elimination obeys to a pseudo-first order kinetic with an apparent rate constant of 0.014 min-1.

Influence of sterilization methods on cell behavior and functionality of osteoblasts cultured on TiO2 nanotubes

International Nuclear Information System (INIS)

Oh, Seunghan; Brammer, Karla S.; Moon, Kyung-Suk; Bae, Ji-Myung; Jin, Sungho

2011-01-01

We investigated the adhesion, proliferation and osteogenic functionality of osteoblasts cultured on titanium dioxide (TiO 2 ) nanotubes in response to different sterilization methods (dry autoclaving vs. wet autoclaving). We prepared various sizes (30-100 nm diameter) of TiO 2 nanotubes on titanium substrates by anodization, sterilized nanotubes by different conditions, and seeded osteoblast cells onto the nanotube surfaces with two different cell seeding densities (10,000 vs. 50,000 cells/well in 12-culture well). The result of this study indicates that the adhesion, proliferation and alkaline phosphatase activity of osteoblasts cultured on only the larger 70 and 100 nm TiO 2 nanotube arrays were dramatically changed by the different sterilization conditions at a low cell seeding density. However, with a higher cell seeding density (50,000 cells/well in 12-cell culture well), the results revealed no significant difference among altered nanotube geometry, 30-100 nm diameters, nor sterilization methods. Next, it was revealed that the nanofeatures of proteins adhered on nanotubular TiO 2 morphology are altered by the sterilization method. It was determined that this protein adhesion effect, in combination with the cell density of osteoblasts seeded onto such TiO 2 nanotube surfaces, has profound effects on cell behavior. This study clearly shows that these are some of the important in vitro culture factors that need to be taken into consideration, as well as TiO 2 nanotube diameters which play an important role in the improvement of cell behavior and functionality.

New Cu-based catalysts supported on TiO2 films for Ullmann SnAr-type C-O coupling reactions

NARCIS (Netherlands)

Benaskar, F.; Engels, V.; Rebrov, E.; Patil, N.G.; Meuldijk, J.; Thuene, P.C.; Magusin, P.C.M.M.; Mezari, B.; Hessel, V.; Hulshof, L.A.; Hensen, E.J.M.; Wheatley, A.E.H.; Schouten, J.C.

2012-01-01

New routes for the preparation of highly active TiO2-supported Cu and CuZn catalysts have been developed for CO coupling reactions. Slurries of a titania precursor were dip-coated onto glass beads to obtain either structured mesoporous or non-porous titania thin films. The Cu and CuZn nanoparticles,

High quantum yield graphene quantum dots decorated TiO{sub 2} nanotubes for enhancing photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Qu, Ailan, E-mail: qal67@163.com; Xie, Haolong; Xu, Xinmei; Zhang, Yangyu; Wen, Shengwu; Cui, Yifan

2016-07-01

Highlights: • High concentration yellow GQDs and TiO{sub 2} nanotubes were achieved by a simple and green method. • High quantum yield GQDs enhanced the photodegradation capacity of TiO{sub 2} nanotube. • The catalytic performance of GQDs/TiO{sub 2} depends on the GQDs loading. • The improved photocatalytic activity of GQDs/TiO{sub 2} was attributed to three aspects. - Abstract: Graphene quantum dots (GQDs) with high quantum yield (about 23.6% at an excitation wavelength of 320 nm) and GQDs/TiO{sub 2} nanotubes (GQDs/TiO{sub 2} NTs) composites were achieved by a simple hydrothermal method at low temperature. Photoluminescence characterization showed that the GQDs exhibited the down-conversion PL features at excitation from 300 to 420 nm and up-conversion photoluminescence in the range of 600–800 nm. The photocatalytic activity of prepared GQDs/TiO{sub 2} NTs composites on the degradation of methyl orange (MO) was significantly enhanced compared with that of pure TiO{sub 2} nanotubes (TiO{sub 2} NTs). For the composites coupling with 1.5%, 2.5% and 3.5% GQDs, the degradation of MO after 20 min irradiation under UV–vis light irradiation (λ = 380–780 nm) were 80.52%, 94.64% and 51.91%, respectively, which are much higher than that of pure TiO{sub 2} NTs (35.41%). It was inferred from the results of characterization that the improved photocatalytic activity of the GQDs/TiO{sub 2} NTs composites was attributed to the synergetic effect of up-conversion properties of the GQDs, enhanced visible light absorption and efficient separation of photogenerated electron-holes of the GQDs/TiO{sub 2} composite.

TiO2 nanotube formation by Ti film anodization and their transport properties for dye-sensitized solar cells

NARCIS (Netherlands)

Iraj, M.; Kolahdouz, M.; Asl-Soleimani, E.; Esmaeili, E.; Kolahdouz Esfahani, Z.

2016-01-01

In this paper, we present the synthesis of TiO2 nanotube (NT) arrays formed by anodization of Ti film deposited on a fluorine-doped tin oxide-coated glass substrate by direct current magnetron sputtering. NH4F/ethylene glycol electrolyte was used to demonstrate the growth of stable nanotubes at room

Structure and dye-sensitized solar cell application of TiO{sub 2} nanotube arrays fabricated by the anodic oxidation method

Energy Technology Data Exchange (ETDEWEB)

Ok, Seon-Yeong; Cho, Kwon-Koo; Kim, Ki-Won [School of Material Science and Engineering, ERI and i-cube center, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of); Ryu, Kwang-Sun, E-mail: kkcho66@gnu.ac.k [Department of Chemistry, University of Ulsan, Ulsan, 680-749 (Korea, Republic of)

2010-05-01

Well-ordered TiO{sub 2} nanotube arrays were fabricated by the potentiostatic anodic oxidation method using pure Ti foil as a working electrode and ethylene glycol solution as an electrolyte with the small addition of NH{sub 4}F and H{sub 2}O. The influence of anodization temperature and time on the morphology and formation of TiO{sub 2} nanotube arrays was examined. The TiO{sub 2} nanotube arrays were applied as a photoelectrode to dye-sensitized solar cells. Regardless of anodizing temperature and time, the average diameter and wall thickness of TiO{sub 2} nanotube arrays show a similar value, whereas the length increases with decreasing reaction temperature. The conversion efficiency is very low, which is due to a morphology breaking of the TiO{sub 2} nanotube arrays in the manufacturing process of a photoelectrode.

Synthesis of Hydroxyapatite/Ag/TiO2 Nanotubes and Evaluation of Their Anticancer Activity on Breast Cancer Cell Line MCF-7

Directory of Open Access Journals (Sweden)

Sara Rahimnejad

2016-06-01

Full Text Available In this research, TiO2 nanotubes were synthesized by anodized oxidation method and were covered with a hydroxyapatite-silver nanoparticles using photodeposition and dip coating for loading silver nanoparticles and coated hydroxyapatite (HA. The morphological texture of TiO2 nanotube and Ag-HA nanoparticles on TiO2 nanotubes surface were studied by field emission scanning electron microscopy (FESEM, energy dispersive X-ray spectroscopy (EDAX analysis and X-ray diffraction (XRD. The MCF-7 cell lines were treated with concentrations 1, 10 and 100 µg/ml of TiO2 nanotubes and HA/Ag/TiO2 nanotube for 24 and 48h. Finally, the cell viability and IC50% were evaluated using MTT assay. The results show that the HA/Ag/TiO2 has more positive effect on enhancing the cell death compare to TiO2 nanotubes and also exerts a time and concentration-dependent inhibition effect on viability of MCF-7 cells

Influence of surface treatment on preparing nanosized TiO2 supported on carbon nanotubes

International Nuclear Information System (INIS)

Wang Shuo; Ji Lijun; Wu Bin; Gong Qianming; Zhu Yuefeng; Liang Ji

2008-01-01

In this paper, nanosize titanium dioxide (TiO 2 ) deposited on pristine and acid treated carbon nanotubes (CNTs) were prepared by a modified sol-gel method. The nanoscale materials were extensively characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR) and Raman spectra. The results indicated that about 6.8 nm TiO 2 nanoparticles were successfully deposited on acid-treated CNTs surface homogeneously and densely, which was smaller than TiO 2 coated on pristine CNTs. The surface state of CNTs was a critical factor in obtaining a homogeneous distribution of nanoscale TiO 2 particles. Acid oxidization could etch the surface of CNTs and introduce functional groups, which were beneficial to controllable homogeneous deposition. The TiO 2 coated on acid-treated CNTs was used as photocatalyst for Reactive Brilliant Red X-3B dye degradation under UV irradiation, which showed higher efficiency than that of TiO 2 coated on pristine CNTs and commercial photocatalyst P25.

Fast fabrication of long TiO2 nanotube array with high photoelectrochemical property on flexible stainless steel.

Science.gov (United States)

Tao, Jie; Wu, Tao; Gao, Peng

2012-03-01

Oriented highly ordered long TiO2 nanotube array films with nanopore structure and high photoelectrochemical property were fabricated on flexible stainless steel substrate (50 microm) by anodization treatment of titanium thin films in a short time. The samples were characterized by means of field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and photoelectrochemical methods, respectively. The results showed that Ti films deposited at the condition of 0.7 Pa Ar pressure and 96 W sputtering power at room temperature was uniform and dense with good homogeneity and high crystallinity. The voltage and the anodization time both played significant roles in the formation of TiO2 nanopore-nanotube array film. The optimal voltage was 60 V and the anodization time is less than 30 min by anodizing Ti films in ethylene glycerol containing 0.5% (w) NH4F and 3% (w) H2O. The growth rate of TiO2 nanotube array was as high as 340 nm/min. Moreover, the photocurrent-potential curves, photocurrent response curves and electrochemical impedance spectra results indicated that the TiO2 nanotube array film with the nanoporous structure exhibited a better photo-response ability and photoelectrochemical performance than the ordinary TiO2 nanotube array film. The reason is that the nanoporous structure on the surface of the nanotube array can separate the photo electron-hole pairs more efficiently and completely than the tubular structure.

An Alternative to Annealing TiO2 Nanotubes for Morphology Preservation: Atmospheric Pressure Plasma Jet Treatment.

Science.gov (United States)

Seo, Sang-Hee; Uhm, Soo-Hyuk; Kwon, Jae-Sung; Choi, Eun Ha; Kim, Kwang-Mahn; Kim, Kyoung-Nam

2015-03-01

Titanium oxide nanotube layer formed by plasma electrolytic oxidation (PEO) is known to be excellent in biomaterial applications. However, the annealing process which is commonly performed on the TiO2 nanotubes cause defects in the nanotubular structure. The purpose of this work was to apply a non-thermal atmospheric pressure plasma jet on diameter-controlled TiO2 nanotubes to mimic the effects of annealing while maintaining the tubular structure for use as biomaterial. Diameter-controlled nanotube samples fabricated by plasma electrolytic oxidation were dried and prepared under three different conditions: untreated, annealed at 450 °C for 1 h in air with a heating rate of 10 °C/min, and treated with an air-based non-thermal atmospheric pressure plasma jet for 5 minutes. The contact angle measurement was investigated to confirm the enhanced hydrophilicity of the TiO2 nanotubes. The chemical composition of the surface was studied using X-ray photoelectron spectroscopy, and the morphology of TiO2 nanotubes was examined by field emission scanning electron microscopy. For the viability of the cell, the attachment of the osteoblastic cell line MC3T3-E1 was determined using the water-soluble tetrazolium salt assay. We found that there are no morphological changes in the TiO2 nanotubular structure after the plasma treatment. Also, we investigated a change in the chemical composition and enhanced hydrophilicity which result in improved cell behavior. The results of this study indicated that the non-thermal atmospheric pressure plasma jet results in osteoblast functionality that is comparable to annealed samples while maintaining the tubular structure of the TiO2 nanotubes. Therefore, this study concluded that the use of a non-thermal atmospheric pressure plasma jet on nanotube surfaces may replace the annealing process following plasma electrolytic oxidation.

Effects of incorporation of 2.5 and 5 wt% TiO2 nanotubes on fracture toughness, flexural strength, and microhardness of denture base poly methyl methacrylate (PMMA).

Science.gov (United States)

Abdulrazzaq Naji, Sahar; Behroozibakhsh, Marjan; Jafarzadeh Kashi, Tahereh Sadat; Eslami, Hossein; Masaeli, Reza; Mahgoli, Hosseinali; Tahriri, Mohammadreza; Ghavvami Lahiji, Mehrsima; Rakhshan, Vahid

2018-04-01

The aim of this preliminary study was to investigate, for the first time, the effects of addition of titania nanotubes (n-TiO 2 ) to poly methyl methacrylate (PMMA) on mechanical properties of PMMA denture base. TiO 2 nanotubes were prepared using alkaline hydrothermal process. Obtained nanotubes were assessed using FESEM-EDX, XRD, and FT-IR. For 3 experiments of this study (fracture toughness, three-point bending flexural strength, and Vickers microhardness), 135 specimens were prepared according to ISO 20795-1:2013 (n of each experiment=45). For each experiment, PMMA was mixed with 0% (control), 2.5 wt%, and 5 wt% nanotubes. From each TiO 2 :PMMA ratio, 15 specimens were fabricated for each experiment. Effects of n-TiO 2 addition on 3 mechanical properties were assessed using Pearson, ANOVA, and Tukey tests. SEM images of n-TiO 2 exhibited the presence of elongated tubular structures. The XRD pattern of synthesized n-TiO 2 represented the anatase crystal phase of TiO 2 . Moderate to very strong significant positive correlations were observed between the concentration of n-TiO 2 and each of the 3 physicomechanical properties of PMMA (Pearson's P value ≤.001, correlation coefficient ranging between 0.5 and 0.9). Flexural strength and hardness values of specimens modified with both 2.5 and 5 wt% n-TiO 2 were significantly higher than those of control ( P ≤.001). Fracture toughness of samples reinforced with 5 wt% n-TiO 2 (but not those of 2.5% n-TiO 2 ) was higher than control ( P =.002). Titania nanotubes were successfully introduced for the first time as a means of enhancing the hardness, flexural strength, and fracture toughness of denture base PMMA.

Nanostructured Ti-Fe{sub 2}O{sub 3}/Cu{sub 2}O heterojunction photoelectrode for efficient hydrogen production

Energy Technology Data Exchange (ETDEWEB)

Sharma, Dipika; Upadhyay, Sumant; Verma, Anuradha [Department of Chemistry, Dayalbagh Educational Institute, Agra-282 110 India (India); Satsangi, Vibha R. [Department of Physics Computer Sciences, Dayalbagh Educational Institute, Agra-282 110 India (India); Shrivastav, Rohit [Department of Chemistry, Dayalbagh Educational Institute, Agra-282 110 India (India); Dass, Sahab, E-mail: drsahabdas@gmail.com [Department of Chemistry, Dayalbagh Educational Institute, Agra-282 110 India (India)

2015-01-01

Nanostructured thin films of pristine Fe{sub 2}O{sub 3}, Ti-doped Fe{sub 2}O{sub 3}, Cu{sub 2}O, and Fe{sub 2}O{sub 3}/Cu{sub 2}O, and Ti-doped Fe{sub 2}O{sub 3}/Cu{sub 2}O heterojunction were deposited on tin-doped indium oxide (Sn:In{sub 2}O{sub 3}) glass substrate using spray pyrolysis method. Ti doping is done to improve photoelectric conversion efficiency and electrical conductivity of hematite thin films. Further enhanced photocurrent is achieved for Ti-Fe{sub 2}O{sub 3}/Cu{sub 2}O heterojunction electrodes. All samples were characterized using X-ray diffractometry, scanning electron microscopy, atomic force microscopy, and UV-Vis spectrometry. Photoelectrochemical properties were also investigated in a three-electrode cell system. UV-Vis absorption spectrum for pristine Fe{sub 2}O{sub 3}, Ti-Fe{sub 2}O{sub 3}, Cu{sub 2}O, Fe{sub 2}O{sub 3}/Cu{sub 2}O, and Ti-Fe{sub 2}O{sub 3}/Cu{sub 2}O heterojunction thin films exhibited absorption in visible region. Nanostructured thin films as prepared were used as photoelectrode in the photoelectrochemical cell for water splitting reaction. Maximum photocurrent density of 2.60 mA/cm{sup 2} at 0.95 V/SCE was exhibited by 454 nm thick Ti-Fe{sub 2}O{sub 3}/Cu{sub 2}O heterojunction photoelectrode. Increased photocurrent density and enhanced incident photon-to-electron conversion efficiency, offered by the heterojunction thin films may be attributed to improved conductivity and efficient separation of the photogenerated charge carriers at the Ti-Fe{sub 2}O{sub 3}/Cu{sub 2}O interface. - Highlights: • Heterojunction thin films were deposited using spray pyrolysis techniques. • Titanium doping in Fe{sub 2}O{sub 3} played a significant role in PEC response. • Ti-Fe{sub 2}O{sub 3}/Cu{sub 2}O heterojunction shows the absorption in visible range. • Improved charge separation and enhanced PEC response were achieved in Ti-Fe{sub 2}O{sub 3}/Cu{sub 2}O.

Self-organized TiO2 nanotubes grown on Ti substrates with different crystallographic preferential orientations: Local structure of TiO2 nanotubes vs. photo-electrochemical response

Czech Academy of Sciences Publication Activity Database

Krbal, M.; Sopha, H.; Pohl, D.; Beneš, L.; Damm, C.; Rellinghaus, B.; Kupčík, Jaroslav; Bezdička, Petr; Šubrt, Jan; Macák, J. M.

2018-01-01

Roč. 264, FEB (2018), s. 393-399 ISSN 0013-4686 Institutional support: RVO:61388980 Keywords : Anatase * Anodization * Photo-current * Stoichiometry * TiO nanotubes 2 Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 4.798, year: 2016

Photocatalytic properties and selective antimicrobial activity of TiO{sub 2}(Eu)/CuO nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Michal, Robert [Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, 84215 Bratislava (Slovakia); Dworniczek, Ewa [Department of Microbiology, Wroclaw Medical University, 50368 Wroclaw (Poland); Caplovicova, Maria [STU Centre for Nanodiagnostics, Slovak University of Technology, 81243 Bratislava (Slovakia); Monfort, Olivier [Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, 84215 Bratislava (Slovakia); Lianos, Panagiotis [Department of Chemical Engineering, University of Patras, 26500 Patras (Greece); Caplovic, Lubomir [Institute of Materials Science, Faculty of Materials Science and Technology, Slovak University of Technology, 91724 Trnava (Slovakia); Plesch, Gustav, E-mail: plesch@fns.uniba.sk [Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, 84215 Bratislava (Slovakia)

2016-05-15

Highlights: • Nanocomposites composed of Eu-doped anatase grafted with CuO. • Increase in photocatalytic hydrogen production due to CuO acting as electrons sink. • CuO in composites decreasing the photoinduced total mineralization of phenol. • Selective photoinduced antimicrobial activity against Enterococcus species. - Abstract: TiO{sub 2}(Eu)/CuO nanocomposites were prepared by precipitation method. The anatase nanocrystallites with a size of 26 nm exhibited well crystallized and characteristical dipyramidal morphology and {1 0 1} and {0 0 1} faceting. Transmission electron microscopy photographs with atomic resolution showed that the Eu(III) dopants were bounded on surface of titania. In the composites, the CuO nanocrystals exhibiting a monoclinic tenorite structure with a size in the range from 2 to 5 nm were grafted to the surface of titania. The influence of copper(II) oxide led to distinct selectivity in the photocatalytic and antimicrobial properties of the investigated TiO{sub 2}(Eu)/CuO nanocomposites. While the presence of CuO nanocrystals strongly increased the photocatalytic production of hydrogen by ethanol reforming, it decreased the activity in photoinduced total mineralization of phenol comparing with non-modified TiO{sub 2}(Eu). In investigated TiO{sub 2}(Eu)/CuO powders, the photoinduced antimicrobial activity against membranes of Enterococcus species was influenced by the selective binding of CuO to the surface of the microorganism leading to distinct selectivity in their action. The activity against Enterococcus faecalis was higher than against Enterococcus faecium.

Attempting to realize n-type BiCuSeO

Science.gov (United States)

Zhang, Xiaoxuan; Feng, Dan; He, Jiaqing; Zhao, Li-Dong

2018-02-01

As an intrinsic p-type semiconductor, BiCuSeO has been widely researched in the thermoelectric community, however, n-type BiCuSeO has not been reported so far. In this work, we successfully realized n-type BiCuSeO through carrying out several successive efforts. Seebeck coefficient of BiCuSeO was increased through introducing extra Bi/Cu to fill the Bi/Cu vacancies that may produce holes, and the maximum Seebeck coefficient was increase from +447 μVK-1 for undoped BiCuSeO to +638 μVK-1 for Bi1.04Cu1.05SeO. The Seebeck coefficient of Bi1.04Cu1.05SeO was changed from p-type to n-type through electron doping through introducing Br/I in Se sites, the maximum negative Seebeck coefficient can reach ∼ -465 μVK-1 and -543 μVK-1 for Bi1.04Cu1.05Se1-xIxO and Bi1.04Cu1.05Se1-xBrxO, respectively. Then, after compositing Bi1.04Cu1.05Se0.99Br0.01O with Ag, n-type BiCuSeO can be absolutely obtained in the whole temperature range of 300-873 K, the maximum ZT 0.05 was achieved at 475 K in the Bi1.04Cu1.05Se0.99Br0.01O+15% Ag. Our report indicates that it is possible to realize n-type conducting behaviors in BiCuSeO system.

Titanium-dioxide nanotube p-n homojunction diode

Science.gov (United States)

Alivov, Yahya; Ding, Yuchen; Singh, Vivek; Nagpal, Prashant

2014-12-01

Application of semiconductors in functional optoelectronic devices requires precise control over their doping and formation of junction between p- and n-doped semiconductors. While doped thin films have led to several semiconductor devices, need for high-surface area nanostructured devices for photovoltaic, photoelectrochemical, and photocatalytic applications has been hindered by lack of desired doping in nanostructures. Here, we show titanium-dioxide (TiO2) nanotubes doped with nitrogen (N) and niobium (Nb) as acceptors and donors, respectively, and formation of TiO2 nanotubes p-n homojunction. This TiO2:N/TiO2:Nb homojunction showed distinct diode-like behaviour with rectification ratio of 1115 at ±5 V and exhibited good photoresponse for ultraviolet light (λ = 365 nm) with sensitivity of 0.19 A/W at reverse bias of -5 V. These results can have important implications for development of nanostructured metal-oxide solar-cells, photodiodes, LED's, photocatalysts, and photoelectrochemical devices.

Titanium-dioxide nanotube p-n homojunction diode

Energy Technology Data Exchange (ETDEWEB)

Alivov, Yahya, E-mail: y.alivov@colorado.edu, E-mail: pnagpal@colorado.edu; Ding, Yuchen; Singh, Vivek [Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Nagpal, Prashant, E-mail: y.alivov@colorado.edu, E-mail: pnagpal@colorado.edu [Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Materials Science and Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Renewable and Sustainable Energy Institute, University of Colorado Boulder, 2445 Kittredge Loop, Boulder, Colorado 80309 (United States)

2014-12-29

Application of semiconductors in functional optoelectronic devices requires precise control over their doping and formation of junction between p- and n-doped semiconductors. While doped thin films have led to several semiconductor devices, need for high-surface area nanostructured devices for photovoltaic, photoelectrochemical, and photocatalytic applications has been hindered by lack of desired doping in nanostructures. Here, we show titanium-dioxide (TiO{sub 2}) nanotubes doped with nitrogen (N) and niobium (Nb) as acceptors and donors, respectively, and formation of TiO{sub 2} nanotubes p-n homojunction. This TiO{sub 2}:N/TiO{sub 2}:Nb homojunction showed distinct diode-like behaviour with rectification ratio of 1115 at ±5 V and exhibited good photoresponse for ultraviolet light (λ = 365 nm) with sensitivity of 0.19 A/W at reverse bias of −5 V. These results can have important implications for development of nanostructured metal-oxide solar-cells, photodiodes, LED's, photocatalysts, and photoelectrochemical devices.

Influence of different types of nanomaterials on their bioaccumulation in a paddy microcosm: A comparison of TiO2 nanoparticles and nanotubes

International Nuclear Information System (INIS)

Yeo, Min-Kyeong; Nam, Dong-Ha

2013-01-01

We investigated the environmental fate and bioaccumulation of TiO 2 nanomaterials in a simplified paddy microcosm over a period of 17 days. Two types of TiO 2 nanomaterials, nanoparticles (TiO 2 -NP) and nanotubes (TiO 2 -NT), were synthesized to have a negative surface charge. Ti concentrations in the environmental media (water, soil), crops (quillworts, water dropworts), and some lower and higher trophic organisms (biofilms, algae, plant-parasitic nematodes, white butterfly larva, mud snail, ricefish) were quantified after exposure periods of 0, 7, and 17 days. The titanium levels of the two nanomaterials were the highest in biofilms during the exposure periods. Bioaccumulation factors indicated that TiO 2 -NP and TiO 2 -NT were largely transferred from a prey (e.g., biofilm, water dropwort) to its consumer (e.g., nematodes, mud snail). Considering the potential entries of such TiO 2 nanomaterials in organisms, their bioaccumulation throughout the food chain should be regarded with great concern in terms of the overall health of the ecosystem. -- Highlights: •A high amount of nanomaterial was transferred within low trophic level organisms. •Nanomaterial transfer occurred from water dropwort roots to nematodes and snails. •Nanomaterial transfer occurred from the biofilm-consuming plankton to ricefish. •TiO 2 nanomaterials can accumulate in the organisms of an artificial ecosystem. -- TiO 2 nanomaterials can accumulate in the organisms of an artificial ecosystem

Preparation of Sb2S3 nanocrystals modified TiO2 dendritic structure with nanotubes for hybrid solar cell

Science.gov (United States)

Li, Yingpin; Wei, Yanan; Feng, Kangning; Hao, Yanzhong; Pei, Juan; Sun, Bao

2018-06-01

Array of TiO2 dendritic structure with nanotubes was constructed on transparent conductive fluorine-doped tin oxide glass (FTO) with titanium potassium oxalate as titanium source. Sb2S3 nanocrystals were successfully deposited on the TiO2 substrate via spin-coating method. Furthermore, TiO2/Sb2S3/P3HT/PEDOT:PSS composite film was prepared by successively spin-coating P3HT and PEDOT:PSS on TiO2/Sb2S3. It was demonstrated that the modification of TiO2 dendritic structure with Sb2S3 could enhance the light absorption in the visible region. The champion hybrid solar cell assembled by TiO2/Sb2S3/P3HT/PEDOT:PSS composite film achieved a power conversion efficiency (PCE) of 1.56%.

Synthesis of Various Metal/TiO2 Core/shell Nanorod Arrays

Science.gov (United States)

Zhu, Wei; Wang, Guan-zhong; Hong, Xun; Shen, Xiao-shuang

2011-02-01

We present a general approach to fabricate metal/TiO2 core/shell nanorod structures by two-step electrodeposition. Firstly, TiO2 nanotubes with uniform wall thickness are prepared in anodic aluminum oxide (AAO) membranes by electrodeposition. The wall thickness of the nanotubes could be easily controlled by modulating the deposition time, and their outer diameter and length are only limited by the channel diameter and the thickness of the AAO membranes, respectively. The nanotubes' tops prepared by this method are open, while the bottoms are connected directly with the Au film at the back of the AAO membranes. Secondly, Pd, Cu, and Fe elements are filled into the TiO2 nanotubes to form core/shell structures. The core/shell nanorods prepared by this two-step process are high density and free-standing, and their length is dependent on the deposition time.

Multistep structural transition of hydrogen trititanate nanotubes into TiO2-B nanotubes: a comparison study between nanostructured and bulk materials

International Nuclear Information System (INIS)

Morgado, Edisson Jr; Jardim, P M; Marinkovic, Bojan A; Rizzo, Fernando C; Abreu, Marco A S de; Zotin, Jose L; Araujo, Antonio S

2007-01-01

H-trititanate nanotubes obtained by alkali hydrothermal treatment of TiO 2 followed by proton exchange were compared to their bulk H 2 Ti 3 O 7 counterpart with respect to their thermally induced structural transformation paths. As-synthesized and heat-treated samples were characterized by XRD, TEM/SAED, DSC and spectroscopy techniques, indicating that H 2 Ti 3 O 7 nanotubes showed the same sequence of structural transformations as their bulk counterpart obtained by conventional solid state reaction. Nanostructured H 2 Ti 3 O 7 converts into TiO 2 (B) via multistep transformation without losing its nanotubular morphology. The transformation occurs between 120 and 400 deg. C through topotactic mechanisms with the intermediate formation of nanostructured H 2 Ti 6 O 13 and H 2 Ti 12 O 25 , which are more condensed layered titanates eventually rearranging to TiO 2 (B). Our results suggest that the intermediate tunnel structure H 2 Ti 12 O 25 is the final layered intermediate phase, on which TiO 2 (B) nucleates and grows. The conversion of nanostructured TiO 2 (B) into anatase is completed at a much lower temperature than its bulk counterpart and is accompanied by loss of the nanotubular morphology

Multistep structural transition of hydrogen trititanate nanotubes into TiO2-B nanotubes: a comparison study between nanostructured and bulk materials.

Science.gov (United States)

Morgado, Edisson; Jardim, P M; Marinkovic, Bojan A; Rizzo, Fernando C; de Abreu, Marco A S; Zotin, José L; Araújo, Antonio S

2007-12-12

H-trititanate nanotubes obtained by alkali hydrothermal treatment of TiO(2) followed by proton exchange were compared to their bulk H(2)Ti(3)O(7) counterpart with respect to their thermally induced structural transformation paths. As-synthesized and heat-treated samples were characterized by XRD, TEM/SAED, DSC and spectroscopy techniques, indicating that H(2)Ti(3)O(7) nanotubes showed the same sequence of structural transformations as their bulk counterpart obtained by conventional solid state reaction. Nanostructured H(2)Ti(3)O(7) converts into TiO(2)(B) via multistep transformation without losing its nanotubular morphology. The transformation occurs between 120 and 400 degrees C through topotactic mechanisms with the intermediate formation of nanostructured H(2)Ti(6)O(13) and H(2)Ti(12)O(25), which are more condensed layered titanates eventually rearranging to TiO(2)(B). Our results suggest that the intermediate tunnel structure H(2)Ti(12)O(25) is the final layered intermediate phase, on which TiO(2)(B) nucleates and grows. The conversion of nanostructured TiO(2)(B) into anatase is completed at a much lower temperature than its bulk counterpart and is accompanied by loss of the nanotubular morphology.

Multistep structural transition of hydrogen trititanate nanotubes into TiO2-B nanotubes: a comparison study between nanostructured and bulk materials

Science.gov (United States)

Morgado, Edisson, Jr.; Jardim, P. M.; Marinkovic, Bojan A.; Rizzo, Fernando C.; de Abreu, Marco A. S.; Zotin, José L.; Araújo, Antonio S.

2007-12-01

H-trititanate nanotubes obtained by alkali hydrothermal treatment of TiO2 followed by proton exchange were compared to their bulk H2Ti3O7 counterpart with respect to their thermally induced structural transformation paths. As-synthesized and heat-treated samples were characterized by XRD, TEM/SAED, DSC and spectroscopy techniques, indicating that H2Ti3O7 nanotubes showed the same sequence of structural transformations as their bulk counterpart obtained by conventional solid state reaction. Nanostructured H2Ti3O7 converts into TiO2(B) via multistep transformation without losing its nanotubular morphology. The transformation occurs between 120 and 400 °C through topotactic mechanisms with the intermediate formation of nanostructured H2Ti6O13 and H2Ti12O25, which are more condensed layered titanates eventually rearranging to TiO2(B). Our results suggest that the intermediate tunnel structure H2Ti12O25 is the final layered intermediate phase, on which TiO2(B) nucleates and grows. The conversion of nanostructured TiO2(B) into anatase is completed at a much lower temperature than its bulk counterpart and is accompanied by loss of the nanotubular morphology.

Double Walled Carbon Nanotube/TiO2 Nanocomposites for Photocatalytic Dye Degradation

Directory of Open Access Journals (Sweden)

Alex T. Kuvarega

2016-01-01

Full Text Available Double walled carbon nanotube (DWCNT/N,Pd codoped TiO2 nanocomposites were prepared by a modified sol-gel method and characterised using FTIR, Raman spectroscopy, TGA, DRUV-Vis, XRD, SEM, and TEM analyses. TEM images showed unique pearl-bead-necklace structured morphologies at higher DWCNT ratios. The nanocomposite materials showed characteristic anatase TiO2 Raman bands in addition to the carbon nanotube D and G bands. Red shifts in the UV-Vis absorption edge were observed at low DWCNT percentages. The photocatalytic activity of DWCNT/N,Pd TiO2 nanocomposite was evaluated by the photocatalytic degradation of eosin yellow under simulated solar light irradiation and the 2% DWCNT/N,Pd TiO2 nanocomposite showed the highest photoactivity while the 20% DWCNT/N,Pd TiO2 hybrid was the least efficient. The photocatalytic enhancement was attributed to the synergistic effects of the supporting and electron channeling role of the DWCNTs as well as the electron trapping effects of the platinum group metal. These phenomena favour the separation of the photogenerated electron-hole pairs, reducing their recombination rate, which consequently lead to significantly enhanced photoactivity.

Three-dimensional hot electron photovoltaic device with vertically aligned TiO2 nanotubes.

Science.gov (United States)

Goddeti, Kalyan C; Lee, Changhwan; Lee, Young Keun; Park, Jeong Young

2018-05-09

Titanium dioxide (TiO 2 ) nanotubes with vertically aligned array structures show substantial advantages in solar cells as an electron transport material that offers a large surface area where charges travel linearly along the nanotubes. Integrating this one-dimensional semiconductor material with plasmonic metals to create a three-dimensional plasmonic nanodiode can influence solar energy conversion by utilizing the generated hot electrons. Here, we devised plasmonic Au/TiO 2 and Ag/TiO 2 nanodiode architectures composed of TiO 2 nanotube arrays for enhanced photon absorption, and for the subsequent generation and capture of hot carriers. The photocurrents and incident photon to current conversion efficiencies (IPCE) were obtained as a function of photon energy for hot electron detection. We observed enhanced photocurrents and IPCE using the Ag/TiO 2 nanodiode. The strong plasmonic peaks of the Au and Ag from the IPCE clearly indicate an enhancement of the hot electron flux resulting from the presence of surface plasmons. The calculated electric fields and the corresponding absorbances of the nanodiode using finite-difference time-domain simulation methods are also in good agreement with the experimental results. These results show a unique strategy of combining a hot electron photovoltaic device with a three-dimensional architecture, which has the clear advantages of maximizing light absorption and a metal-semiconductor interface area.

Effect of TiO2 nanotube length and lateral tubular spacing on ...

Indian Academy of Sciences (India)

Abstract. The main objective of this study is to show the effect of TiO2 nanotube length, diameter and intertubular ... formation of nanotube arrays spread uniformly over a large area. ... 36, 48 and 72 h at an applied voltage of 40 V. The anodized ... and phase analysis for the obtained nanotubes were done .... Using an extra-.

Anodization parameters influencing the morphology and electrical properties of TiO{sub 2} nanotubes for living cell interfacing and investigations

Energy Technology Data Exchange (ETDEWEB)

Khudhair, D. [Deakin University, Waurn Ponds Campus, Vic 3216 (Australia); Bhatti, A., E-mail: asim.bhatti@deakin.edu.au [Deakin University, Waurn Ponds Campus, Vic 3216 (Australia); Li, Y. [RMIT University, Bundoora, Victoria 3083 (Australia); Hamedani, H. Amani; Garmestani, H. [Georgia Institute of Technology, GA 30332 (United States); Hodgson, P.; Nahavandi, S. [Deakin University, Waurn Ponds Campus, Vic 3216 (Australia)

2016-02-01

Nanotube structures have attracted tremendous attention in recent years in many applications. Among such nanotube structures, titania nanotubes (TiO{sub 2}) have received paramount attention in the medical domain due to their unique properties, represented by high corrosion resistance, good mechanical properties, high specific surface area, as well as great cell proliferation, adhesion and mineralization. Although lot of research has been reported in developing optimized titanium nanotube structures for different medical applications, however there is a lack of unified literature source that could provide information about the key parameters and experimental conditions required to develop such optimized structure. This paper addresses this gap, by focussing on the fabrication of TiO{sub 2} nanotubes through anodization process on both pure titanium and titanium alloys substrates to exploit the biocompatibility and electrical conductivity aspects, critical factors for many medical applications from implants to in-vivo and in-vitro living cell studies. It is shown that the morphology of TiO{sub 2} directly impacts the biocompatibility aspects of the titanium in terms of cell proliferation, adhesion and mineralization. Similarly, TiO{sub 2} nanotube wall thickness of 30–40 nm has shown to exhibit improved electrical behaviour, a critical factor in brain mapping and behaviour investigations if such nanotubes are employed as micro–nano-electrodes. - Highlights: • We spotlight on the importance of TiO{sub 2} nanotubes in medical applications. • The influence of nanotubes morphology on the electrical conductivity and biocompatibility properties • Influence of key anodizing parameters on the nanotube morphology • Methods to improve the electrical conductivity of TiO{sub 2} nanotubes • Potential of employment of TiO{sub 2} nanotubes as micro–nano-electrodes.

Optical, structural and photocatalysis properties of Cu-doped TiO{sub 2} thin films

Energy Technology Data Exchange (ETDEWEB)

Bensouici, F., E-mail: fbensouici@yahoo.fr [Department of Physics, URMPE Unite, UMBB University, 35000 Boumerdes (Algeria); Bououdina, M.; Dakhel, A.A. [Department of Physics, College of Science, University of Bahrain, PO Box 32038 (Bahrain); Tala-Ighil, R.; Tounane, M.; Iratni, A. [Department of Physics, URMPE Unite, UMBB University, 35000 Boumerdes (Algeria); Souier, T. [Department of Physics, College of Science, Sultan Qaboos University, PO Box 36 (Oman); Liu, S.; Cai, W. [Key laboratory of Materials Physics, Anhui Key Laboratory of Nanomaterials and Technology, Center for Environmental and Energy Nanomaterials, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China)

2017-02-15

Highlights: • A simple chemical route to obtain thin layers of Cu doped TiO{sub 2}. • Detailed structure analysis was carried out by Rietveld refinements. • Forming the CuO phase decreases the efficiency photocatalysis of TiO{sub 2}. - Abstract: Pure and Cu{sup +2} doped TiO{sub 2} thin films have been successfully deposited onto glass substrate by sol–gel dip-coating. The films were annealed at 450 °C for 1 h and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM-EDX), atomic force microscopy (AFM), UV–vis spectrophotometer and photocatalytic degradation of methylene blue. XRD confirmed the presence of two phases at higher Cu concentration; TiO{sub 2} anatase and CuO. AFM analysis showed that the surface roughness increases within increasing Cu content as well as the presence of large aggregates at higher Cu content. SEM observations confirmed the granular structure of the films, and EDX analysis revealed a low solubility limit (effective doping) of Cu into TiO{sub 2} lattice. It was found that the optical band gap energy decreases with increasing Cu content. At constant irradiation time, the photo-degradation of methylene blue rate decreased with increasing concentration of Cu{sup +2}.

Photoactive layered nanocomposites obtained by direct transferring of anodic TiO{sub 2} nanotubes to commodity thermoplastics

Energy Technology Data Exchange (ETDEWEB)

Sanz, Ruy, E-mail: ruy.sanzgonzalez@cnr.it [CNR-IMM, Via Santa Sofia 64, I-95123 Catania (Italy); Buccheri, Maria Antonietta; Zimbone, Massimo; Scuderi, Viviana; Amiard, Guillaume; Impellizzeri, Giuliana [CNR-IMM, Via Santa Sofia 64, I-95123 Catania (Italy); Romano, Lucia [CNR-IMM, Via Santa Sofia 64, I-95123 Catania (Italy); Department of Physics, University of Catania, Via Santa Sofia 64, I-95123 Catania (Italy); Privitera, Vittorio [CNR-IMM, Via Santa Sofia 64, I-95123 Catania (Italy)

2017-03-31

Highlights: • Rapid and scalable synthesis of flexible photoactive layered nanocomposites is presented. • The nanocomposites show similar photonic efficiencies to TiO{sub 2} nanotubes and commercial products. • The nanocomposites exhibit antibacterial properties under 1 mW cm{sup −2} UVA. • The synthesis process is solvent-free and reduces the amount of raw materials. - Abstract: TiO{sub 2} nanotubes demonstrated to be a versatile nanostructure for biomaterials, clean energy and water remediation applications. However, the cost of titanium and the poor mechanical properties of the nanotubes hinder their adoption at large scale. This work presents a straightforward and scalable method for transferring photoactive anodic TiO{sub 2} nanotubes from titanium foils to commodity thermoplastic polymers, polypropylene, polyethylene terephthalate, polycarbonate, and polymethylmetacrylate, allowing the reusing of the remaining titanium. The obtained flexible nanocomposites reach a maximum photonic efficiencies of 0.038% (ISO-10678:2010) representing the 93% of photonic efficiency of TiO{sub 2} nanotubes on titanium. In addition, the nanocomposites and TiO{sub 2} nanotubes on titanium present similar antibacterial properties under 1 mW cm{sup −2} UV-A, 60% of Escherichia coli survival after 1 h of exposition. The final objective of this work is to point out main concepts and key parameters for a low-cost fabrication of a photoactive nanocomposite material.

SURFACE MODIFICATION OF SEMICONDUCTOR THIN FILM OF TiO2 ON GRAPHITE SUBSTRATE BY Cu-ELECTRODEPOSITION

Directory of Open Access Journals (Sweden)

Fitria Rahmawati

2010-06-01

Full Text Available Surface modification of graphite/TiO2 has been done by mean of Cu electrodeposition. This research aims to study the effect of Cu electrodeposition on photocatalytic enhancing of TiO2. Electrodeposition has been done using CuSO4 0,4 M as the electrolyte at controlled current. The XRD pattern of modified TiO2 thin film on graphite substrate exhibited new peaks at 2θ= 43-44o and 2θ= 50-51o that have been identified as Cu with crystal cubic system, face-centered crystal lattice and crystallite size of 26-30 nm. CTABr still remains in the material as impurities. Meanwhile, based on morphological analysis, Cu particles are dissipated in the pore of thin film. Graphite/TiO2/Cu has higher photoconversion efficiency than graphite/TiO2.   Keywords: semiconductor, graphite/TiO2, Cu electrodeposition

Synergistic Effect of Cu2O and Urea as Modifiers of TiO2 for Enhanced Visible Light Activity

Directory of Open Access Journals (Sweden)

Marcin Janczarek

2018-06-01

Full Text Available Low cost compounds, i.e., Cu2O and urea, were used as TiO2 modifiers to introduce visible light activity. Simple and cheap methods were applied to synthesize an efficient and stable nanocomposite photocatalytic material. First, the core-shell structure TiO2–polytriazine derivatives were prepared. Thereafter, Cu2O was added as the second semiconductor to form a dual heterojunction system. Enhanced visible light activity was found for the above-mentioned nanocomposite, confirming a synergistic effect of Cu2O and urea (via polytriazine derivatives on titania surface. Two possible mechanisms of visible light activity of the considered material were proposed regarding the type II heterojunction and Z-scheme through the essential improvement of the charge separation effect.

Incorporation of Cu{sub 2}O nanocrystals into TiO{sub 2} photonic crystal for enhanced UV–visible light driven photocatalysis

Energy Technology Data Exchange (ETDEWEB)

Geng, Zhi; Zhang, Yu; Yuan, Xing; Huo, Mingxin; Zhao, Yahui; Lu, Ying, E-mail: luy332@nenu.edu.cn; Qiu, Yue

2015-09-25

Highlights: • The Cu{sub 2}O NCs/TiO{sub 2} PC composite was synthesized and exhibited high photocatalysis. • The improved light harvesting and increased quantum yield was achieved. • The hydroxyl radical was the primary oxidant in Cu{sub 2}O NCs/TiO{sub 2} PC photocatalysis. - Abstract: A 3D UV–visible light responsive photocatalyst was fabricated by infiltrating Cu{sub 2}O nanocrystals (NCs) into TiO{sub 2} photonic crystal (PC). Morphology characterization presented that Cu{sub 2}O NCs with average diameter around 10 nm were dispersed uniformly into TiO{sub 2} PC. The transmittance spectra showed that Cu{sub 2}O NCs/TiO{sub 2} 260, prepared by integrating Cu{sub 2}O NCs with TiO{sub 2} 260 which was fabricated from 260 nm polystyrene spheres, exhibited the highest light harvesting. The photoluminescence spectra confirmed the electron/hole pairs recombination of Cu{sub 2}O NCs/TiO{sub 2} 260 was efficiently inhibited due to the unique heterojunction structure between TiO{sub 2} and Cu{sub 2}O. In the photocatalytic degradation of Rhodamine B and Bisphenol A under UV–visible light (320 nm < λ < 780 nm) irradiation, the kinetic constant using Cu{sub 2}O NCs/TiO{sub 2} 260 was 3.99 and 8.37-fold larger than that using TiO{sub 2} nanoparticle (NP), respectively. The enhanced photocatalysis benefited from the increased light harvesting owing to the excitation of both TiO{sub 2} and Cu{sub 2}O NCs whose optical absorption was intensified by the photonic effect of TiO{sub 2} 260 and the high quantum efficiency due to the Cu{sub 2}O/TiO{sub 2} heterojunction. The hydroxyl radical, generated from the protonation of superoxide radical which was derived from the reduction of oxygen by photogenerated electrons, was the main oxidant responsible for pollutant degradation.

Dye-sensitized solar cells based on Cr-doped TiO2 nanotube photoanodes

Institute of Scientific and Technical Information of China (English)

M.M.Momeni

2017-01-01

The effect of chromium doping on the photovoltaic efficiency of dye-sensitized solar cells (DSSCs) with anodized TiO2 nanotubes followed by an annealing process was investigated.Cr-doped TiO2 nanotubes (CrTNs) with different amounts of chromium were obtained by anodizing of titanium foils in a single-step process using potassium chromate as the chromium source.Film features were investigated by scanning electron microscopy (SEM),X-ray diffraction (XRD),energy-dispersive X-ray spectroscopy (EDX),and ultraviolet-visible (UV-Vis) spectroscopy.It is clearly seen that highly ordered TiO2 nanotubes are formed in an anodizing solution free of potassium chromate,and with a gradual increase in the potassium chromate concentration,these nanotube structures change to nanoporous and compact films without porosity.The photovoltaic efficiencies of fabricated DSSCs were characterized by a solar cell measurement system via the photocurrent-voltage (Ⅰ-Ⅴ) curves.It is found that the photovoltaic efficiency of DSSCs with CrTNsl sample is improved by more than three times compared to that of DSSCs with undoped TNs.The energy conversion efficiency increases from 1.05 ％ to 3.89 ％ by doping of chromium.

Optimization of TiO2/Cu/TiO2 multilayers as a transparent composite electrode deposited by electron-beam evaporation at room temperature

Science.gov (United States)

Sun, Hong-Tao; Wang, Xiao-Ping; Kou, Zhi-Qi; Wang, Li-Jun; Wang, Jin-Ye; Sun, Yi-Qing

2015-04-01

Highly transparent indium-free composite electrodes of TiO2/Cu/TiO2 are deposited by electron-beam evaporation at room temperature. The effects of Cu thickness and annealing temperature on the electrical and optical properties of the multilayer film are investigated. The critical thickness of Cu mid-layer to form a continuous conducting layer is found to be 11 nm. The multilayer with a mid-Cu thickness of 11 nm is optimized to obtain a resistivity of 7.4×10-5 Ω·cm and an average optical transmittance of 86% in the visible spectral range. The figure of merit of the TiO2/Cu(11 nm)/TiO2 multilayer annealed at 150 °C reaches a minimum resistivity of 5.9×10-5 Ω·cm and an average optical transmittance of 88% in the visible spectral range. The experimental results indicate that TiO2/Cu/TiO2 multilayers can be used as a transparent electrode for solar cell and other display applications. Project supported by the Research Innovation Key Project of Education Committee of Shanghai, China (Grant No. 14ZZ137) and the National Cultivation Fund from University of Shanghai for Science and Technology (Grant No. 14XPM04).

Electrical transport through Pb(Zr,Ti)O3 p-n and p-p heterostructures modulated by bound charges at a ferroelectric surface: Ferroelectric p-n diode

Science.gov (United States)

Watanabe, Yukio

1999-05-01

Current through (Pb,La)(Zr,Ti)O3 ferroelectrics on perovskite semiconductors is found to exhibit diode characteristics of which polarity is universally determined by the carrier conduction-type semiconductors. A persisting highly reproducible resistance modulation by a dc voltage, which has a short retention, is observed and is ascribed to a band bending of the ferroelectric by the formation of charged traps. This interpretation is consistent with a large relaxation current observed at a low voltage. On the other hand, a reproducible resistance modulation by a pulse voltage, which has a long retention, is observed in metal/(Pb,La)(Zr,Ti)O3/SrTiO3:Nb but not in metal/(Pb,La)(Zr,Ti)O3/(La,Sr)2CuO4 and is attributed to a possible band bending due to the spontaneous polarization (P) switching. The observed current voltage (IV) characteristics, the polarity dependence, the relaxation, and the modulation are explicable, if we assume a p-n or a p-p junction at the ferroelectric semiconductor interface (p: hole conduction type, n: electron conduction type). The analysis suggests that an intrinsically inhomogeneous P (∇P) near the ferroelectric/metal interface is likely very weak or existing in a very thin layer, when a reaction of the metal with the ferroelectric is eliminated. Additionally, the various aspects of transport through ferroelectrics are explained as a transport in the carrier depleted region.

Electrodeposition synthesis of MnO{sub 2}/TiO{sub 2} nanotube arrays nanocomposites and their visible light photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Xu, Xuyao [School of Chemistry Science and Technology, and Institute of Physical Chemistry, Zhanjiang Normal University, Zhanjiang 524048 (China); Zhou, Xiaosong, E-mail: zxs801213@163.com [School of Chemistry Science and Technology, and Institute of Physical Chemistry, Zhanjiang Normal University, Zhanjiang 524048 (China); Li, Xiaoyu, E-mail: lixiaoyu@iga.ac.cn [Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Science, Changchun 130012 (China); Yang, Fei [The State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research of Chinese Academy of Sciences, 11A, Datun Road, Chaoyang District, Beijing 100101 (China); Jin, Bei; Xu, Tan; Li, Guosheng; Li, Manyi [School of Chemistry Science and Technology, and Institute of Physical Chemistry, Zhanjiang Normal University, Zhanjiang 524048 (China)

2014-11-15

Highlights: • MnO{sub 2}/TiO{sub 2} nanotube arrays nanocomposites are prepared by electrodeposition. • MnO{sub 2}/TiO{sub 2} exhibits high visible light photocatalytic activity. • The results of XRD show the depositions are attributed to α-MnO{sub 2}. • A photocatalytic mechanism is discussed under visible light irradiation. - Abstract: MnO{sub 2}/TiO{sub 2} nanotube arrays nanocomposite photocatalysts have been synthesized through an electrodeposition method. X-ray powder diffraction analysis and X-ray photoelectron spectroscopy measurements reveal that the products of electrodeposition method are MnO{sub 2}. Scanning electron microscopy measurements suggest that the depositions are deposited on the surface or internal of the nanotube. UV–vis light absorbance spectra demonstrate the excellent adsorption properties of MnO{sub 2}/TiO{sub 2} over the whole region of visible light, which enables this novel photocatalytic material to possess remarkable activity in the photocatalytic degradation of acid Orange II under visible light radiation. Moreover, a possible photocatalytic mechanism is discussed.

Enhancement in photo-electrochemical efficiency by reducing recombination rate in branched TiO2 nanotube array on functionalizing with ZnO micro crystals

Science.gov (United States)

Boda, Muzaffar Ahmad; Ashraf Shah, Mohammad

2018-06-01

In this study, branched TiO2 nanotube array were fabricated through electrochemical anodization process at constant voltage using third generation electrolyte. On account of morphological advantage, these nanotubes shows significant enhancement in photo-electrochemical property than compact or conventional titania nanotube array. However, their photo-electrochemical efficiency intensifies on coating with ZnO micro-crystals. ZnO coated branched TiO2 nanotube array shows a photocurrent density of 27.8 mA cm‑2 which is 1.55 times the photocurrent density (17.2 mA cm‑2) shown by bare branched titania nanotubes. The significant enhancement in photocurrent density shown by the resulting ZnO/TiO2 hybrid structure is attributed to suppression in electron–hole recombination phenomenon by offering smooth pathway to photo generated excitons on account of staggered band edge positions in individual semiconductors.

Heterostructured ZnFe2O4/Fe2TiO5/TiO2 Composite Nanotube Arrays with an Improved Photocatalysis Degradation Efficiency Under Simulated Sunlight Irradiation

Science.gov (United States)

Xiong, Kun; Wang, Kunzhou; Chen, Lin; Wang, Xinqing; Fan, Qingbo; Courtois, Jérémie; Liu, Yuliang; Tuo, Xianguo; Yan, Minhao

2018-03-01

To improve the visible light absorption and photocatalytic activity of titanium dioxide nanotube arrays (TONTAs), ZnFe2O4 (ZFO) nanocrystals were perfused into pristine TONTA pipelines using a novel bias voltage-assisted perfusion method. ZFO nanocrystals were well anchored on the inner walls of the pristine TONTAs when the ZFO suspensions (0.025 mg mL-1) were kept under a 60 V bias voltage for 1 h. After annealing at 750 °C for 2 h, the heterostructured ZFO/Fe2TiO5 (FTO)/TiO2 composite nanotube arrays were successfully obtained. Furthermore, Fe3+ was reduced to Fe2+ when solid solution reactions occurred at the interface of ZFO and the pristine TONTAs. Introducing ZFO significantly enhanced the visible light absorption of the ZFO/FTO/TONTAs relative to that of the annealed TONTAs. The coexistence of type I and staggered type II band alignment in the ZFO/FTO/TONTAs facilitated the separation of photogenerated electrons and holes, thereby improving the efficiency of the ZFO/FTO/TONTAs for photocatalytic degradation of methylene blue when irradiated with simulated sunlight. [Figure not available: see fulltext.

New vision to CuO, ZnO, and TiO2 nanoparticles: their outcome and effects

Science.gov (United States)

Chibber, Sandesh; Ansari, Shakeel Ahmed; Satar, Rukhsana

2013-04-01

Nanomaterials and nanotechnology have attracted more and more attention due to their wide ranges of applications in various fields. With a high level of surface energy, high magnetism, high surface area, and low melting point, engineered nanoparticles (ENPs) has been widely used in industry for various applications. Metal nanoparticles, in particular, have been shown to cause significant biological effects. Review discusses cytotoxic to neurotoxic effects of CuO, ZnO, and TiO2 nanoparticles based on the scenario drawn from various in vitro and in vivo studies. ENPs such as TiO2 and ZnO NPs have great practical importance in industrial applications. CuO NPs is also widely used in biomedical applications as catalyst supports, drug carriers, and gene delivery. However, study conducted on TiO2 NPs have forecast that oxidative DNA damage could be attributed due to reduced glutathione levels with concomitant increase in lipid peroxidation and reactive oxygen species generation. Moreover, there are many evidences showing that ZnO NP and CuO NPs generates ROS production and can cause cell death in different types of cultured cell. Nanoparticle toxicity is assessed by set of tests designed to characterize a given risk and also the mechanism for related outcomes. Conclusively, it becomes more and more important for nanotechnologist to understand the potential health effects of ENPs and what new methodology can be applied to reveal problems like gene silencing and inhibition in antioxidant defense mechanism which can be occurred on severe effects to oxidative stress by ENPs.

New vision to CuO, ZnO, and TiO2 nanoparticles: their outcome and effects

International Nuclear Information System (INIS)

Chibber, Sandesh; Ansari, Shakeel Ahmed; Satar, Rukhsana

2013-01-01

Nanomaterials and nanotechnology have attracted more and more attention due to their wide ranges of applications in various fields. With a high level of surface energy, high magnetism, high surface area, and low melting point, engineered nanoparticles (ENPs) has been widely used in industry for various applications. Metal nanoparticles, in particular, have been shown to cause significant biological effects. Review discusses cytotoxic to neurotoxic effects of CuO, ZnO, and TiO 2 nanoparticles based on the scenario drawn from various in vitro and in vivo studies. ENPs such as TiO 2 and ZnO NPs have great practical importance in industrial applications. CuO NPs is also widely used in biomedical applications as catalyst supports, drug carriers, and gene delivery. However, study conducted on TiO 2 NPs have forecast that oxidative DNA damage could be attributed due to reduced glutathione levels with concomitant increase in lipid peroxidation and reactive oxygen species generation. Moreover, there are many evidences showing that ZnO NP and CuO NPs generates ROS production and can cause cell death in different types of cultured cell. Nanoparticle toxicity is assessed by set of tests designed to characterize a given risk and also the mechanism for related outcomes. Conclusively, it becomes more and more important for nanotechnologist to understand the potential health effects of ENPs and what new methodology can be applied to reveal problems like gene silencing and inhibition in antioxidant defense mechanism which can be occurred on severe effects to oxidative stress by ENPs.

Scanning electron microscopy of heat treated TiO2 nanotubes arrays obtained by anodic oxidation

Science.gov (United States)

Naranjo, D. I.; García-Vergara, S. J.; Blanco, S.

2017-12-01

Scanning electron microscopy was used to investigate the anatase-rutile transformation of self-organized TiO2 nanotubes obtained on titanium foil by anodizing and subsequent heat treatment. The anodizing was carried out at 20V in an 1% v/v HF acid and ethylene glycol:water (50:50) electrolyte at room temperature. The anodized samples were initially pre-heat treated at 450°C for 4 hours to modify the amorphous structure of TiO2 nanotubes into anatase structure. Then, the samples were heated between 600 to 800°C for different times, in order to promote the transformation to rutile structure. The formation of TiO2 nanotubes is evident by SEM images. Notably, when the samples are treated at high temperature, the formation of rutile crystals starts to become evident at the nanotubes located on the originally grain boundaries of the titanium. Thus, the anatase - rutile transformation has a close relationship with the microstructure of the titanium, more exactly with grain boundaries.

Ag-bridged Ag{sub 2}O nanowire network/TiO{sub 2} nanotube array p–n heterojunction as a highly efficient and stable visible light photocatalyst

Energy Technology Data Exchange (ETDEWEB)

Liu, Chengbin, E-mail: chem_cbliu@hnu.edu.cn [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063 (China); State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Cao, Chenghao [State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Luo, Xubiao [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063 (China); Luo, Shenglian [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063 (China); State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China)

2015-03-21

Graphical abstract: A unique Ag-bridged Ag{sub 2}O nanowire network/TiO{sub 2} nanotube array p–n heterojunction was fabricated by simple electrochemical method. The heterostructures exhibit high photocatalytic activity and excellent recycling performance. - Highlights: • Ag-bridged Ag{sub 2}O nanowire network self-stability structure. • Ag{sub 2}O nanowire network/TiO{sub 2} nanotube p–n heterojunction. • High visible light photocatalytic activity. • Highly stable recycling performance. - Abstract: A unique Ag-bridged Ag{sub 2}O nanowire network/TiO{sub 2} nanotube array p–n heterojunction (Ag–Ag{sub 2}O/TiO{sub 2} NT) was fabricated by simple electrochemical method. Ag nanoparticles were firstly electrochemically deposited onto the surface of TiO{sub 2} NT and then were partly oxidized to Ag{sub 2}O nanowires while the rest of Ag mother nanoparticles were located at the junctions of Ag{sub 2}O nanowire network. The Ag–Ag{sub 2}O/TiO{sub 2} NT heterostructure exhibited strong visible-light response, effective separation of photogenerated carriers, and high adsorption capacity. The integration of Ag–Ag{sub 2}O self-stability structure and p–n heterojunction permitted high and stable photocatalytic activity of Ag–Ag{sub 2}O/TiO{sub 2} NT heterostructure photocatalyst. Under 140-min visible light irradiation, the photocatalytic removal efficiency of both dye acid orange 7 (AO7) and industrial chemical p-nitrophenol (PNP) over Ag–Ag{sub 2}O/TiO{sub 2} NT reached nearly 100% much higher than 17% for AO7 or 13% for PNP over bare TiO{sub 2} NT. After 5 successive cycles under 600-min simulated solar light irradiation, Ag–Ag{sub 2}O/TiO{sub 2} NT remained highly stable photocatalytic activity.

Asymmetric photoelectric property of transparent TiO2 nanotube films loaded with Au nanoparticles

International Nuclear Information System (INIS)

Wang, Hui; Liang, Wei; Liu, Yiming; Zhang, Wanggang; Zhou, Diaoyu; Wen, Jing

2016-01-01

Highlights: • Highly transparent films of TiO 2 nanotube arrays were directly fabricated on FTO glasses. • Semitransparent TNT-Au composite films were obtained and exhibited excellent photoelectrocatalytic ability. • Back-side of TNT-Au composite films was firstly irradiated and tested to compare with front-side of films. - Abstract: Semitransparent composite films of Au loaded TiO 2 nanotubes (TNT-Au) were prepared by sputtering Au nanoparticles on highly transparent TiO 2 nanotubes films, which were fabricated directly on FTO glasses by anodizing the Ti film sputtered on the FTO glasses. Compared with pure TNT films, the prepared TNT-Au films possessed excellent absorption ability and high photocurrent response and improved photocatalytic activity under visible-light irradiation. It could be concluded that Au nanoparticles played important roles in improving the photoelectrochemical performance of TNT-Au films. Moreover, in this work, both sides of TNT-Au films were researched and compared owing to theirs semitransparency. It was firstly found that the photoelectric activity of TNT-Au composite films with back-side illumination was obviously superior to front-side illumination.

Rapid charge-discharge property of Li4Ti5O12-TiO2 nanosheet and nanotube composites as anode material for power lithium-ion batteries.

Science.gov (United States)

Yi, Ting-Feng; Fang, Zi-Kui; Xie, Ying; Zhu, Yan-Rong; Yang, Shuang-Yuan

2014-11-26

Well-defined Li4Ti5O12-TiO2 nanosheet and nanotube composites have been synthesized by a solvothermal process. The combination of in situ generated rutile-TiO2 in Li4Ti5O12 nanosheets or nanotubes is favorable for reducing the electrode polarization, and Li4Ti5O12-TiO2 nanocomposites show faster lithium insertion/extraction kinetics than that of pristine Li4Ti5O12 during cycling. Li4Ti5O12-TiO2 electrodes also display lower charge-transfer resistance and higher lithium diffusion coefficients than pristine Li4Ti5O12. Therefore, Li4Ti5O12-TiO2 electrodes display lower charge-transfer resistance and higher lithium diffusion coefficients. This reveals that the in situ TiO2 modification improves the electronic conductivity and electrochemical activity of the electrode in the local environment, resulting in its relatively higher capacity at high charge-discharge rate. Li4Ti5O12-TiO2 nanocomposite with a Li/Ti ratio of 3.8:5 exhibits the lowest charge-transfer resistance and the highest lithium diffusion coefficient among all samples, and it shows a much improved rate capability and specific capacity in comparison with pristine Li4Ti5O12 when charging and discharging at a 10 C rate. The improved high-rate capability, cycling stability, and fast charge-discharge performance of Li4Ti5O12-TiO2 nanocomposites can be ascribed to the improvement of electrochemical reversibility, lithium ion diffusion, and conductivity by in situ TiO2 modification.

Fabrication of Cu2O-TiO2 Nano-composite with High Photocatalytic Performance under Simulated Solar Light

Directory of Open Access Journals (Sweden)

Yi Wentao

2016-01-01

Full Text Available Cu2O-P25 (TiO2 nano-heterostructures with different mass ratios were synthesized via a wet chemical precipitation and hydrothermal method, and were characterized by X-ray diffraction (XRD, field-emission scanning electron microscopy (FESEM, UV-vis diffuse reflectance spectra (DRS, and X-ray photoelectron spectroscopy (XPS. DRS results showed that the light absorption of P25 extended to the visible light region with the loading of Cu2O. XPS results showed that Cu existed in the state of Cu+ in the presence of hydroxylamine hydrochloride, confirming the formation of Cu2O. The obtained products exhibited efficient photocatalytic performance in degradation of methyl orange (MO and methylene blue (MB under simulated solar light. The sample of 5% Cu2O-P25 exhibited the highest photocatalytic activity among all as-prepared samples. And the photocatalysts can be recycled without obvious loss of photocatalytic activity.

Synthesis of Cu{sub 2}O/graphene/rutile TiO{sub 2} nanorod ternary composites with enhanced photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Sun, Mingxuan, E-mail: mingxuansun@sues.edu.cn; Fang, Yalin; Wang, Ying; Sun, Shanfu; He, Jia; Yan, Zhi

2015-11-25

A ternary composite of Cu{sub 2}O, graphene and rutile TiO{sub 2} nanorods was prepared using Cu(CH{sub 3}COO){sub 2}·H{sub 2}O, graphene oxide and TiCl{sub 4} as the starting materials and its enhanced photocatalytic performance was demonstrated. Graphene/TiO{sub 2} nanorod composites (GT) were obtained by a simple hydrothermal method and then, Cu{sub 2}O was coupled onto the surface of graphene/rutile TiO{sub 2} to form Cu{sub 2}O/graphene/rutile TiO{sub 2} nanorod (CGT) composites via a chemical bath deposition process. The as-prepared sample was characterized by X-ray diffraction (XRD), emission field scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), specific surface area analyzer (BET), Raman spectroscopy and ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS). It is found that the introduction of graphene and Cu{sub 2}O has little effect on the morphology of TiO{sub 2} nanorods with average dimensions of 140 nm (length) × 30 nm (diameter) (L/D ratio ≈5). A red shift of light absorption edge and more absorption in the visible light region were observed for the resulted ternary samples compared with TiO{sub 2} and graphene/TiO{sub 2} composites. The photocatalytic activity was evaluated by the photodegradation of methylene blue under visible light irradiation, which showed 2.8 times corresponding enhancement of the degradation efficiency for the ternary composites compared with TiO{sub 2}. This work provides a new strategy to improve the visible light response of TiO{sub 2} and facilitate its application in environmental remediation. - Highlights: • A ternary composite of Cu{sub 2}O/graphene/rutile TiO{sub 2} nanorods were successfully fabricated. • Red shift and more absorption in the visible light region were observed for the ternary composites. • Improved photocatalytic degradation was detected with the introduction of Cu{sub 2}O and graphene. • Both Cu{sub 2}O and graphene played an important role

Interface interaction and wetting of Sc2O3 exposed to Cu-Al and Cu-Ti melts

International Nuclear Information System (INIS)

Barzilai, S.; Nagar, H.; Froumin, N.; Frage, N.; Aizenshtein, M.

2009-01-01

Scandia is a thermodynamically stable oxide and could be used as a structural material for a crucible in order to avoid a melt contamination. In the present study wetting experiments of Cu-Al and Cu-Ti melts on Scandia substrate were preformed at 1423 K by a sessile drop method. It was established that Al and Ti additions lead to the improved wetting and that the final contact angle decreases with increasing the additives concentration. For Al containing melts, the contact angle changes gradually with time, and a relatively thick interaction layer, which consists of Al 2 O 3 , Sc 2 O 3 , and metallic channels, was formed at the Sc 2 O 3 /Cu-Al interface. For Ti containing melts, the final contact angle is achieved already during heating, and an extremely thin layer based on a Ti-Sc-O compound was detected by AES at the Sc 2 O 3 /Cu-Ti interface. The results of a thermodynamic analysis, which takes into account the formation free energy of the oxides, involved in the systems, and the thermodynamic properties of the liquid solutions are in a good agreement with the experimental observations. (orig.)

Fabrication and photoelectrochemical properties of ZnS/Au/TiO2 nanotube array films.

Science.gov (United States)

Zhu, Yan-Feng; Zhang, Juan; Xu, Lu; Guo, Ya; Wang, Xiao-Ping; Du, Rong-Gui; Lin, Chang-Jian

2013-03-21

A highly ordered TiO(2) nanotube array film was fabricated by an anodic oxidation method. The film was modified by Au nanoparticles (NPs) formed by a deposition-precipitation technique and was covered with a thin ZnS shell prepared by a successive ionic layer adsorption and reaction (SILAR) method. The photoelectrochemical properties of the prepared ZnS/Au/TiO(2) composite film were evaluated by incident photon-to-current conversion efficiency (IPCE), and photopotential and electrochemical impedance spectroscopy (EIS) measurements under white light illumination. The results indicated that the Au NPs could expand the light sensitivity range of the film and suppress the electron-hole recombination, and the ZnS shell could inhibit the leakage of photogenerated electrons from the surface of Au NPs to the ZnS/electrolyte interface. When the 403 stainless steel in a 0.5 M NaCl solution was coupled to the ZnS/Au/TiO(2) nanotube film photoanode under illumination, its potential decreased by 400 mV, showing that the composite film had a better photocathodic protection effect on the steel than that of a pure TiO(2) nanotube film.

Deep-level transient spectroscopy of TiO2/CuInS2 heterojunctions

NARCIS (Netherlands)

Nanu, M.; Boulch, F.; Schoonman, J.; Goossens, A.

2005-01-01

Deep-level transient spectroscopy (DLTS) has been used to measure the concentration and energy position of deep electronic states in CuInS2. Flat TiO2?CuInS2 heterojunctions as well as TiO2-CuInS2 nanocomposites have been investigated. Subband-gap electronic states in CuInS2 films are mostly due to

Characteristics of N-doped TiO{sub 2} nanotube arrays by N{sub 2}-plasma for visible light-driven photocatalysis

Energy Technology Data Exchange (ETDEWEB)

Liu Xu [College of Chemical Engineering, Sichuan University, Chengdu 610065 (China); Liu Zhongqing, E-mail: 301zql@vip.sina.com [College of Chemical Engineering, Sichuan University, Chengdu 610065 (China); Zheng Jian; Yan Xin; Li Dandan; Chen Si [College of Chemical Engineering, Sichuan University, Chengdu 610065 (China); Chu Wei, E-mail: chuwei1965_scu@yahoo.com [College of Chemical Engineering, Sichuan University, Chengdu 610065 (China)

2011-10-13

Highlights: > A new pathway is provided to prepare N-doped TiO2 nanotube arrays using N{sub 2}-plasma treatment. > N{sub 2}-plasma treatment did not wreck the structure of nanotube arrays. > Nitrogen doping promoted the phase transition to rutile phase at low annealing temperatures > Nitrogen doping narrow band gap of TiO{sub 2} and improve the photocatalytic activity of samples. - Abstract: N-doped TiO{sub 2} nanotube arrays were prepared by electrochemical anode oxidation of Ti foil followed by treatment with N{sub 2}-plasma and subsequent annealed under Ar atmosphere. The morphologies, composition and optical properties of N-doped TiO{sub 2} nanotube arrays were characterized using field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction spectrometer (XRD), Photoluminescence (PL) and UV-vis diffusion reflection spectroscopy (UV-vis DRS). Methylene blue (MB) solution was utilized as the degradation model to evaluate the photocatalytic activity of the samples under visible light irradiation. The results suggested N{sub 2}-plasma treatment created doping of nitrogen onto the surface of photoelectrodes successfully and the N-doped TiO{sub 2} nanotube arrays display a significantly enhancement of the photocatalytic activity comparing with the pure TiO{sub 2} nanotube arrays under the visible light irradiation.

Surface accumulation conduction controlled sensing characteristic of p-type CuO nanorods induced by oxygen adsorption

International Nuclear Information System (INIS)

Wang, C; Fu, X Q; Xue, X Y; Wang, Y G; Wang, T H

2007-01-01

P-type CuO nanorods were synthesized by a hydrothermal method and the ethanol-sensing properties of sensors based on CuO were investigated. The sensor resistance increased when it was exposed to ethanol and decreased in the air, which is contrary to the case for sensors realized from n-type semiconductor. The resistance of the CuO-based sensor was about 2 kΩ in air and 6 kΩ in ethanol vapour with concentration of 2000 ppm. Such a sensing property is attributed to surface accumulation conduction. Sensors based on CuO nanorods have potential applications in detecting ethanol in low concentration

Heterojunction solar cell with 6% efficiency based on an n-type aluminum-gallium-oxide thin film and p-type sodium-doped Cu2O sheet

Science.gov (United States)

Minami, Tadatsugu; Nishi, Yuki; Miyata, Toshihiro

2015-02-01

In this paper, we describe efforts to enhance the efficiency of Cu2O-based heterojunction solar cells fabricated with an aluminum-gallium-oxide (Al-Ga-O) thin film as the n-type layer and a p-type sodium (Na)-doped Cu2O (Cu2O:Na) sheet prepared by thermally oxidizing copper sheets. The optimal Al content [X; Al/(Ga + Al) atomic ratio] of an AlX-Ga1-X-O thin-film n-type layer was found to be approximately 2.5 at. %. The optimized resistivity was approximately 15 Ω cm for n-type AlX-Ga1-X-O/p-type Cu2O:Na heterojunction solar cells. A MgF2/AZO/Al0.025-Ga0.975-O/Cu2O:Na heterojunction solar cell with 6.1% efficiency was fabricated using a 60-nm-thick n-type oxide thin-film layer and a 0.2-mm-thick Cu2O:Na sheet with the optimized resistivity.

Synthesis of Ag-loaded SrTiO{sub 3}/TiO{sub 2} heterostructure nanotube arrays for enhanced photocatalytic performances

Energy Technology Data Exchange (ETDEWEB)

Hu, Zijun; Chen, Da; Zhan, Xiaqiang; Wang, Fang; Qin, Laishun; Huang, Yuexiang [China Jiliang University, College of Materials Science and Engineering, Hangzhou, Zhejiang (China)

2017-06-15

In this work, the effect of loading Ag nanoparticles on the photocatalytic activity of SrTiO{sub 3}/TiO{sub 2} nanotube arrays (TNTAs) was investigated. TNTAs were partially transformed to SrTiO{sub 3} through a hydrothermal treatment, which could preserve the tubular structure of TNTAs, and then, Ag nanoparticles were well deposited on the surface of SrTiO{sub 3}/TNTAs heterostructure by a chemical reduction process. Compared to the TNTAs sample, the Ag-loaded SrTiO{sub 3}/TNTAs sample showed significantly enhanced photocatalytic activities for photodegradation of rhodamine B. The enhanced photocatalytic activity of Ag-loaded SrTiO{sub 3}/TNTAs could be attributed to the increased optical absorption as well as the efficient charge transfer and separation of photogenerated electron-hole pairs induced by the SrTiO{sub 3}/TNTAs heterojunction and the Schottky barrier between metallic Ag and SrTiO{sub 3}/TNTAs. On the basis of the trapping experiments, the possible photocatalytic mechanism was also discussed. (orig.)

The evolution of interface microstructure in a ZrO2/Ag-Cu-Al-Ti system

International Nuclear Information System (INIS)

Lee, Youngmin; Yu, Jin

1993-01-01

Among ceramic/metal (C/M) joining technologies, the active filler metal method has been studied extensively due to the simple brazing process and excellent joint strength. Active metal elements, typically Ti, are intentionally added to braze alloys to enhance the formation of reaction products between the ceramic and the braze metal at the C/M interface. In the brazing of Al 2 O 3 with the Ag-Cu-Ti filler metal, reaction products such as γ-TiO, Cu 2 (Ti, Al) 4 O, Ti 3 (Cu 0.76 Al 0.18 Sn 0.06 ) 3 O were found, while products such as Ti 5 Si 3 and TiN formed in the brazing of Si 3 N 4 . The presence of reaction layers at the C/M interface influences the interface strength in a complex way. In Cu/Al 2 O 3 , Co/Al 2 O 3 , Ni/Al 2 O 3 , and Cu/diamond systems, maxima of joint strength were observed at some intermediate Ti addition, while the flexural strength decreased substantially with the thickening of the TiO layer in a ZrO 2 /Ag-Cu-Sn-Ti system. Thus, composition of the braze alloy (particularly, the content of the active metal), process conditions such as brazing temperature and time, microstructure and mechanical properties of reaction products at the C/M interfaces, interfacial chemistry, and residual stress are primary factors to be studied in order to understand the strengths of the C/M interfaces systematically. In the present and the following papers, evolutions of interfacial microstructures at various brazing conditions, and corresponding interface strengths are reported, respectively, for a ZrO 2 /Ag-Cu-Al-Ti system

Evaluation of thermodynamic and kinetic stability of P-type transparent conducting oxide, SrCu2O2 under various oxygen partial pressures

International Nuclear Information System (INIS)

Sugimoto, Takayuki; Yanagawa, Atsumi; Hashimoto, Takuya

2012-01-01

Highlights: ▶ Thermodynamic and kinetic stabilities of SrCu 2 O 2 under various P(O 2 ) was estimated. ▶ The reaction rate for decomposition decreased with decreasing temperature and P(O 2 ). ▶ The activation energy for decomposition of SrCu 2 O 2 was estimated to be 66 kJ/mol. ▶ SrCu 2 O 2 showed less stability than those of other transparent p-type semiconductors. - Abstract: Kinetic stability of transparent p-type conducting oxide, SrCu 2 O 2 , has been evaluated by using X-ray diffraction measurement and thermogravimetry. It was revealed that SrCu 2 O 2 decomposed to mixture of CuO and Sr 14 Cu 24 O 41 in air at temperatures above 300 °C. The decomposition reaction rate can be successfully explained by kinetic model assuming first-order chemical reaction. The rate constant can be suppressed with decreasing temperature and oxygen partial pressure. The activation energy for decomposition reaction of SrCu 2 O 2 calculated from Arrhenius plot was 66 kJ/mol, which was lower than those of other transparent p-type semiconductors such as CuAlO 2 and CuGaO 2 . The low decomposition temperature and activation energy for decomposition indicate that chemical stability of SrCu 2 O 2 is far lower than those of other p-type conducting oxides.

Polyoxometalate-modified TiO2 nanotube arrays photoanode materials for enhanced dye-sensitized solar cells

Science.gov (United States)

Liu, Ran; Sun, Zhixia; Zhang, Yuzhuo; Xu, Lin; Li, Na

2017-10-01

In this work, we prepared for the first time the TiO2 nanotube arrays (TNAs) photoanode with polyoxometalate(POMs)-modified TiO2 electron-transport layer for improving the performance of zinc phthalocyanine(ZnPc)-sensitized solar cells. The as-prepared POMs/TNAs/ZnPc composite photoanode exhibited higher photovoltaic performances than the TNAs/ZnPc photoanode, so that the power conversion efficiency of the solar cell device based on the POMs/TNAs/ZnPc photoanode displayed a notable improvement of 45%. These results indicated that the POMs play a key role in reducing charge recombination in phthalocyanine-sensitized solar cells, together with TiO2 nanotube arrays being helpful for electron transport. The mechanism of the performance improvement was demonstrated by the measurements of electrochemical impedance spectra and open-circuit voltage decay curves. Although the resulting performance is still below that of the state-of-the-art dye-sensitized solar cells, this study presents a new insight into improving the power conversion efficiency of phthalocyanine-sensitized solar cells via polyoxometalate-modified TiO2 nanotube arrays photoanode.

Multistep structural transition of hydrogen trititanate nanotubes into TiO{sub 2}-B nanotubes: a comparison study between nanostructured and bulk materials

Energy Technology Data Exchange (ETDEWEB)

Morgado, Edisson Jr [PETROBRAS S.A./CENPES, Research and Development Centre, Avenida Horacio Macedo, 950, Cidade Universitaria, Quadra 7, 21941-598 Rio de Janeiro-RJ (Brazil); Jardim, P M [Department of Materials Science and Metallurgy, Pontifical Catholic University, CP 38008, 22453-900 Rio de Janeiro-RJ (Brazil); Marinkovic, Bojan A [Department of Materials Science and Metallurgy, Pontifical Catholic University, CP 38008, 22453-900 Rio de Janeiro-RJ (Brazil); Rizzo, Fernando C [Department of Materials Science and Metallurgy, Pontifical Catholic University, CP 38008, 22453-900 Rio de Janeiro-RJ (Brazil); Abreu, Marco A S de [PETROBRAS S.A./CENPES, Research and Development Centre, Avenida Horacio Macedo, 950, Cidade Universitaria, Quadra 7, 21941-598 Rio de Janeiro-RJ (Brazil); Zotin, Jose L [PETROBRAS S.A./CENPES, Research and Development Centre, Avenida Horacio Macedo, 950, Cidade Universitaria, Quadra 7, 21941-598 Rio de Janeiro-RJ (Brazil); Araujo, Antonio S [Department of Chemistry, Federal University of Rio Grande do Norte, CP 1662, 59078-970 Natal-RN (Brazil)

2007-12-12

H-trititanate nanotubes obtained by alkali hydrothermal treatment of TiO{sub 2} followed by proton exchange were compared to their bulk H{sub 2}Ti{sub 3}O{sub 7} counterpart with respect to their thermally induced structural transformation paths. As-synthesized and heat-treated samples were characterized by XRD, TEM/SAED, DSC and spectroscopy techniques, indicating that H{sub 2}Ti{sub 3}O{sub 7} nanotubes showed the same sequence of structural transformations as their bulk counterpart obtained by conventional solid state reaction. Nanostructured H{sub 2}Ti{sub 3}O{sub 7} converts into TiO{sub 2}(B) via multistep transformation without losing its nanotubular morphology. The transformation occurs between 120 and 400 deg. C through topotactic mechanisms with the intermediate formation of nanostructured H{sub 2}Ti{sub 6}O{sub 13} and H{sub 2}Ti{sub 12}O{sub 25}, which are more condensed layered titanates eventually rearranging to TiO{sub 2}(B). Our results suggest that the intermediate tunnel structure H{sub 2}Ti{sub 12}O{sub 25} is the final layered intermediate phase, on which TiO{sub 2}(B) nucleates and grows. The conversion of nanostructured TiO{sub 2}(B) into anatase is completed at a much lower temperature than its bulk counterpart and is accompanied by loss of the nanotubular morphology.

Efficient suppression of nanograss during porous anodic TiO2 nanotubes growth

Science.gov (United States)

Gui, Qunfang; Yu, Dongliang; Li, Dongdong; Song, Ye; Zhu, Xufei; Cao, Liu; Zhang, Shaoyu; Ma, Weihua; You, Shiyu

2014-09-01

When Ti foil was anodized in fluoride-containing electrolyte for a long time, undesired etching-induced "nanograss" would inevitably generate on the top of porous anodic TiO2 nanotubes (PATNTs). The nanograss will hinder the ions transport and in turn yield depressed (photo) electrochemical performance. In order to obtain nanograss-free nanotubes, a modified three-step anodization and two-layer nanostructure of PATNTs were designed to avoid the nanograss. The first layer (L1) nanotubes were obtained by the conventional two-step anodization. After washing and drying processes, the third-step anodization was carried out with the presence of L1 nanotubes. The L1 nanotubes, serving as a sacrificed layer, was etched and transformed into nanograss, while the ultralong nanotubes (L2) were maintained underneath the L1. The bi-layer nanostructure of the nanograss/nanotubes (L1/L2) was then ultrasonically rinsed in deionized water to remove the nanograss (L1 layer). Then much longer nanotubes (L2 layer) with intact nanotube mouths could be obtained. Using this novel approach, the ultralong nanotubes without nanograss can be rationally controlled by adjusting the anodizing times of two layers.

Effect of RGD Peptide-Coated TiO2 Nanotubes on the Attachment, Proliferation, and Functionality of Bone-Related Cells

Directory of Open Access Journals (Sweden)

Seunghan Oh

2013-01-01

Full Text Available The purpose of this research was to characterize an Arg-Gly-Asp (RGD peptide immobilized on TiO2 nanotubes. In addition, we investigated the effects of the RGD peptide-coated TiO2 nanotubes on the cellular response, proliferation, and functionality of osteogenic-induced human mesenchymal stem cells (hMSCs, which are osteoclasts that have been induced by bone marrow macrophages. The RGD peptide was grafted covalently onto the surface of TiO2 nanotubes based on the results of SEM, FT-IR, and XPS. Furthermore, the RGD peptide promoted the initial attachment and proliferation of the hMSCs, regardless of the size of the TiO2 nanotubes. However, the RGD peptide did not prominently affect the osteogenic functionality of the hMSCs because the peptide suppressed hMSC motility associated with osteogenic differentiation. The result of an in vitro osteoclast test showed that the RGD peptide accelerated the initial attachment of preosteoclasts and the formation of mature osteoclasts, which could resorb the bone matrix. Therefore, we believe that an RGD coating on TiO2 nanotubes synthesized on Ti implants might not offer significant acceleration of bone formation in vivo because osteoblasts and osteoclasts reside in the same compartment.

Degradation of paracetamol by advance oxidation processes using modified reticulated vitreous carbon electrodes with TiO(2) and CuO/TiO(2)/Al(2)O(3).

Science.gov (United States)

Arredondo Valdez, H C; García Jiménez, G; Gutiérrez Granados, S; Ponce de León, C

2012-11-01

The degradation of paracetamol in aqueous solutions in the presence of hydrogen peroxide was carried out by photochemistry, electrolysis and photoelectrolysis using modified 100 pores per inch reticulated vitreous carbon electrodes. The electrodes were coated with catalysts such as TiO(2) and CuO/TiO(2)/Al(2)O(3) by electrophoresis followed by heat treatment. The results of the electrolysis with bare reticulated vitreous carbon electrodes show that 90% paracetamol degradation occurs in 4 h at 1.3 V vs. SCE, forming intermediates such as benzoquinone and carboxylic acids followed by their complete mineralisation. When the electrolysis was carried out with the modified electrodes such as TiO(2)/RVC, 90% degradation was achieved in 2 h while with CuO/TiO(2)/Al(2)O(3)/RVC, 98% degradation took only 1 h. The degradation was also carried out in the presence of UV reaching 95% degradation with TiO(2)/RVC/UV and 99% with CuO/TiO(2)/Al(2)O(3)/RVC/UV in 1 h. The reactions were followed by spectroscopy UV-Vis, HPLC and total organic carbon analysis. These studies show that the degradation of paracetamol follows a pseudo-first order reaction kinetics. Copyright © 2012 Elsevier Ltd. All rights reserved.

Synthesis and Characterization of TiO2(B Nanotubes Prepared by Hydrothermal Method Using [Ti8O12(H2O24]Cl8.HCl.7H2O as Precursor

Directory of Open Access Journals (Sweden)

Hari Sutrisno

2010-04-01

Full Text Available Low-dimension TiO2-related material has been synthesized by hydrothermal treatment of [Ti8O12(H2O24]Cl8.HCl.7H2O crystal as precursor in a 10 M NaOh aqueous solution at 150 C for 24 h. Characterization of the obtained product was carried out by a range of techniques including X-ray diffraction (XRD, high resolution scanning electron microscopy (HRSEM, high resolution transmission electron microscopy (HRTEM, Raman spectroscopy and nitrogen adsorption-desorption isotherm (Brunauer-Emmett-Teller (BET-Barret-Joyner-Halender (BJH. From HRTEM, XRD and Raman spectra showed that the obtained product has a TiO2(B structure. According to HRTEM observations, it was found that TiO2(B has nanotubular structure with approximately 5-8 nm in outer and 3-6 nm in inner diameter. The BET surface area of TiO2(B nanotubes is quiet large, values of 418.3163 m2/g being obtained. Pore structure analyisis by the BJH method showed that the average pore diameter of TiO2(B nanotubes has 5.5781 nm.

Influence of Different Defects in Vertically Aligned Carbon Nanotubes on TiO2 Nanoparticle Formation through Atomic Layer Deposition.

Science.gov (United States)

Acauan, Luiz; Dias, Anna C; Pereira, Marcelo B; Horowitz, Flavio; Bergmann, Carlos P

2016-06-29

The chemical inertness of carbon nanotubes (CNT) requires some degree of "defect engineering" for controlled deposition of metal oxides through atomic layer deposition (ALD). The type, quantity, and distribution of such defects rules the deposition rate and defines the growth behavior. In this work, we employed ALD to grow titanium oxide (TiO2) on vertically aligned carbon nanotubes (VACNT). The effects of nitrogen doping and oxygen plasma pretreatment of the CNT on the morphology and total amount of TiO2 were systematically studied using transmission electron microscopy, Raman spectroscopy, and thermogravimetric analysis. The induced chemical changes for each functionalization route were identified by X-ray photoelectron and Raman spectroscopies. The TiO2 mass fraction deposited with the same number of cycles for the pristine CNT, nitrogen-doped CNT, and plasma-treated CNT were 8, 47, and 80%, respectively. We demonstrate that TiO2 nucleation is dependent mainly on surface incorporation of heteroatoms and their distribution rather than structural defects that govern the growth behavior. Therefore, selecting the best way to functionalize CNT will allow us to tailor TiO2 distribution and hence fabricate complex heterostructures.

Sn doped TiO{sub 2} nanotube with oxygen vacancy for highly efficient visible light photocatalysis

Energy Technology Data Exchange (ETDEWEB)

Li, Jinliang; Xu, Xingtao [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Materials Science, Department of Physics, East China Normal University, Shanghai 200062 (China); Liu, Xinjuan [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Yu, Caiyan; Yan, Dong; Sun, Zhuo [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Materials Science, Department of Physics, East China Normal University, Shanghai 200062 (China); Pan, Likun, E-mail: lkpan@phy.ecnu.edu.cn [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Materials Science, Department of Physics, East China Normal University, Shanghai 200062 (China)

2016-09-15

Sn doped TiO{sub 2} nanotube with oxygen vacancy (V{sub o}-Sn−TiO{sub 2}) was successfully synthesized via a facile hydrothermal process and subsequent annealing in nitrogen atmosphere. The morphology, structure and photocatalytic performance of V{sub o}-Sn−TiO{sub 2} in the degradation of nitrobenzene were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, UV–vis absorption spectroscopy, nitrogen adsorption-desorption and electrochemical impedance spectra, respectively. The inner diameter, outer diameter and specific surface area of V{sub o}-Sn−TiO{sub 2} are about 5 nm, 15 nm and 235.54 m{sup 2} g{sup −1}, respectively. The experimental results show that the V{sub o}-Sn−TiO{sub 2} exhibits excellent photocatalytic performance with a maximum degradation rate of 92% in 300 min for nitrobenzene and 94% in 100 min for Rhodamine B and corresponding mineralization rates of 68% and 70% under visible light irradiation. The improved photocatalytic performance is ascribed to the enhanced light absorption and specific surface area as well as the reduced electron-hole pair recombination with the presence of oxygen vacancy and Sn doping in the TiO{sub 2} nanotube. - Highlights: • Photocatalysis is an environmental-friendly technology for nitrobenzene removal. • Sn doped TiO{sub 2} nanotube with oxygen vacancy is fabricated for the first time. • It exhibits excellent photocatalytic performance in degradation of nitrobenzene. • A high degradation rate of 92% is achieved under visible light irradiation.

Properties of Sn-doped TiO2 nanotubes fabricated by anodization of co-sputtered Ti–Sn thin films

International Nuclear Information System (INIS)

Kyeremateng, Nana Amponsah; Hornebecq, Virginie; Knauth, Philippe; Djenizian, Thierry

2012-01-01

Self-organized Sn-doped TiO 2 nanotubes (nts) were fabricated for the first time, by anodization of co-sputtered Ti and Sn thin films. This nanostructured material was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, UV–vis spectroscopy and transmission electron microscopy. Due to their remarkable properties, Sn-doped TiO 2 nts can find potential applications in Li-ion microbatteries, photovoltaics, and catalysis. Particularly, the electrochemical performance as an anode material for Li-ion microbatteries was evaluated in Li test cells. With current density of 70 μA cm −2 (1 C) and cut-off potential of 1 V, Sn-doped TiO 2 nts showed improved performance compared to simple TiO 2 nts, and differential capacity plots revealed that the material undergoes full electrochemical reaction as a Rutile-type TiO 2 .

Using Ag-embedded TiO{sub 2} nanotubes array as recyclable SERS substrate

Energy Technology Data Exchange (ETDEWEB)

Ling, Yunhan, E-mail: yhling@mail.tsinghua.edu.cn [Lab of Advanced Materials, School of Materials Science & Engineering, Tsinghua University, Beijing 100084 (China); Zhuo, Yuqing; Huang, Liang [Lab of Advanced Materials, School of Materials Science & Engineering, Tsinghua University, Beijing 100084 (China); Mao, Duolu [School of Physical and Electronic Information Engineering, Qinghai Nationalities University, Xining, Qinghai 810007 (China)

2016-12-01

Highlights: • Ag embedded nanoparticles inside nanotube have better SERS enhancement than surface cap. • Ag NPs reconstruction via self-migration with UV and humidity control. • Self-cleaning effects both on organic molecule photo-oxidation as well as Ag ions photo-reduction. - Abstract: A simple strategy for synthesizing Ag-loaded TiO{sub 2} nanotube film for use as multifunctional photocatalyst and recyclable surface-enhanced Raman scattering (SERS) substrate is introduced. Highly aligned TiO{sub 2} nanotube arrays (TNTA) prepared via electrochemical anodization were used as a 3D rough host for silver nanoparticles. Ag deposits were sputtered in a vacuum, and it was found that their morphologies were mainly influenced by the diameters of nanotubes and the UV irradiation induced aging process, especially the self-migration of silver along the tubular wall. SERS and the self-cleaning effect were observed using Rhodamine 6G (R6G) as the probe molecule. The results showed that narrow nanotube and silver nanoparticles embedment contributed significantly to both the phenomenal SERS and recyclability.

A Au/Cu2O-TiO2 system for photo-catalytic hydrogen production. A pn-junction effect or a simple case of in situ reduction?

KAUST Repository

Sinatra, Lutfan

2015-02-01

Photo-catalytic H2 production from water has been studied over Au-Cu2O nanoparticle deposited on TiO2 (anatase) in order to probe into both the plasmon resonance effect (Au nanoparticles) and the pn-junction at the Cu2O-TiO2 interface. The Au-Cu2O composite is in the form of ∼10 nm Au nanoparticles grown on ∼475 nm Cu2O octahedral nanocrystals with (111) facets by partial galvanic replacement. X-ray Photoelectron Spectroscopy (XPS) Cu2p and Auger L3M4,5M4,5 lines indicate that the surface of Cu2O is mainly composed of Cu+. The rate for H2 production (from 95 water/5 ethylene glycol; vol.%) over 2 wt.% (Au/Cu2O)-TiO2 is found to be ∼10 times faster than that on 2 wt.% Au-TiO2 alone. Raman spectroscopy before and after reaction showed the disappearance of Cu+ lines (2Eu) at 220 cm-1. These observations coupled with the induction time observed for the reaction rate suggest that in situ reduction from Cu+ to Cu0 occurs upon photo-excitation. The reduction requires the presence of TiO2 (electron transfer). The prolonged activity of the reaction (with no signs of deactivation) despite the reduction to Cu0 indicates that the latter takes part in the reaction by providing additional sites for the reaction, most likely as recombination centers for hydrogen atoms to form molecular hydrogen. This phenomenon provides an additional route for enhancing the efficiency and lifetime of Cu2O-TiO2 photocatalytic systems, beyond the usually ascribed pn-junction effect.

Hydrogen production by tailoring the brookite and Cu2O ratio of sol-gel Cu-TiO2 photocatalysts.

Science.gov (United States)

Hinojosa-Reyes, Mariana; Camposeco-Solís, Roberto; Zanella, Rodolfo; Rodríguez González, Vicente

2017-10-01

Cu-TiO 2 photocatalysts were prepared by the sol-gel method. Copper loadings from, 1.0 to 5.0 wt % were used. The materials were annealed at different temperatures (from 400 to 600 °C) to study the formation of brookite and copper ionic species. The photocatalysts were characterized by X-ray diffraction, UV-vis, Raman and XPS spectroscopies, H 2 -temperature programmed reduction (TPR), N 2 physisorption, and SEM-EDS to quantify the actual copper loadings and characterize morphology. The photocatalysts were evaluated during the hydrogen photocatalytic production using an ethanolic solution (50% v/v) under UV and visible radiation. The best hydrogen production was performed by Ti-Cu 1.0 with an overall hydrogen production that was five times higher than that obtained with photolysis. This sample had an optimal thermal treatment at 500 °C, and at this temperature, the Cu 2 O and brookite/anatase ratio boosted the photocatalytic production of hydrogen. In addition, a deactivation test was carried out for the most active sample (TiO 2 -Cu 1.0), showing unchanged H 2 production for three cycles with negligible Cu lixiviation. The activity of hydrogen-through-copper production reported in this research work is comparable with the one featured by noble metals and that reported in the literature for doped TiO 2 materials. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis and Photocatalytic Activity of Anatase TiO2 Nanoparticles-coated Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Xie Yi

2009-01-01

Full Text Available Abstract A simple and straightforward approach to prepare TiO2-coated carbon nanotubes (CNTs is presented. Anatase TiO2 nanoparticles (NPs with the average size ~8 nm were coated on CNTs from peroxo titanic acid (PTA precursor even at low temperature of 100 °C. We demonstrate the effects of CNTs/TiO2 molar ratio on the adsorption capability and photocatalytic efficiency under UV–visible irradiation. The samples showed not only good optical absorption in visible range, but also great adsorption capacity for methyl orange (MO dye molecules. These properties facilitated the great enhancement of photocatalytic activity of TiO2 NPs-coated CNTs photocatalysts. The TiO2 NPs-coated CNTs exhibited 2.45 times higher photocatalytic activity for MO degradation than that of pure TiO2.

Enhanced Photocatalytic Activity of La3+-Doped TiO2 Nanotubes with Full Wave-Band Absorption

Science.gov (United States)

Xia, Minghao; Huang, Lingling; Zhang, Yubo; Wang, Yongqian

2018-06-01

TiO2 nanotubes doped with La3+ were synthesized by anodic oxidation method and the photocatalytic activity was detected by photodegrading methylene blue. As-prepared samples improved the absorption of both ultraviolet light and visible light and have a great enhancement on the photocatalytic activity while contrasting with the pristine TiO2 nanotubes. A tentative mechanism for the enhancement of photocatalytic activity with full wave-band absorption is proposed.

Photocatalytic Degradation of DIPA Using Bimetallic Cu-Ni/TiO2 Photocatalyst under Visible Light Irradiation

Science.gov (United States)

Bustam, Mohamad Azmi; Chong, Fai Kait; Man, Zakaria B.; Khan, Muhammad Saqib; Shariff, Azmi M.

2014-01-01

Bimetallic Cu-Ni/TiO2 photocatalysts were synthesized using wet impregnation (WI) method with TiO2 (Degussa-P25) as support and calcined at different temperatures (180, 200, and 300°C) for the photodegradation of DIPA under visible light. The photocatalysts were characterized using TGA, FESEM, UV-Vis diffuse reflectance spectroscopy, fourier transform infrared spectroscopy (FTIR) and temperature programmed reduction (TPR). The results from the photodegradation experiments revealed that the Cu-Ni/TiO2 photocatalysts exhibited much higher photocatalytic activities compared to bare TiO2. It was found that photocatalyst calcined at 200°C had the highest photocatalyst activities with highest chemical oxygen demand (COD) removal (86.82%). According to the structural and surface analysis, the enhanced photocatalytic activity could be attributed to its strong absorption into the visible region and high metal dispersion. PMID:25105158

Photocatalytic Degradation of DIPA Using Bimetallic Cu-Ni/TiO2 Photocatalyst under Visible Light Irradiation

Directory of Open Access Journals (Sweden)

Nadia Riaz

2014-01-01

Full Text Available Bimetallic Cu-Ni/TiO2 photocatalysts were synthesized using wet impregnation (WI method with TiO2 (Degussa-P25 as support and calcined at different temperatures (180, 200, and 300°C for the photodegradation of DIPA under visible light. The photocatalysts were characterized using TGA, FESEM, UV-Vis diffuse reflectance spectroscopy, fourier transform infrared spectroscopy (FTIR and temperature programmed reduction (TPR. The results from the photodegradation experiments revealed that the Cu-Ni/TiO2 photocatalysts exhibited much higher photocatalytic activities compared to bare TiO2. It was found that photocatalyst calcined at 200°C had the highest photocatalyst activities with highest chemical oxygen demand (COD removal (86.82%. According to the structural and surface analysis, the enhanced photocatalytic activity could be attributed to its strong absorption into the visible region and high metal dispersion.

Antibacterial activity and inflammation inhibition of ZnO nanoparticles embedded TiO2 nanotubes

Science.gov (United States)

Yao, Shenglian; Feng, Xujia; Lu, Jiaju; Zheng, Yudong; Wang, Xiumei; Volinsky, Alex A.; Wang, Lu-Ning

2018-06-01

Titanium (Ti) with nanoscale structure on the surface exhibits excellent biocompatibility and bone integration. Once implanted, the surgical implantation may lead to bacterial infection and inflammatory reaction, which cause the implant failure. In this work, irregular and nanorod-shaped ZnO nanoparticles were doped into TiO2 nanotubes (TNTs) with inner diameter of about 50 nm by electro-deposition. The antibacterial properties of ZnO incorporated into TiO2 nanotubes (TNTs/ZnO) were evaluated using Staphylococcus aureus (S. aureus). Zn ions released from the nanoparticles and the morphology could work together, improving antibacterial effectiveness up to 99.3% compared with the TNTs. Macrophages were cultured on the samples to determine their respective anti-inflammatory properties. The proliferation and viability of macrophages were evaluated by the CCK-8 method and Live&Dead stain, and the morphology of the cells was observed by scanning electron microscopy. Results indicated that TNTs/ZnO has a significant inhibitory effect on the proliferation and adhesion of macrophages, which could be used to prevent chronic inflammation and control the inflammatory reaction. Besides, the release of Zn ions from the ZnO nanoparticles is a long-term process, which could be beneficial for bone integration. Results demonstrate that ZnO deposited into TNTs improved the antibacterial effectiveness and weakened the inflammatory reaction of titanium-based implants, which is a promising approach to enhance their bioactivity.

Ag and CdS nanoparticles co-sensitized TiO2 nanotubes for enhancing visible photoelectrochemical performance

International Nuclear Information System (INIS)

Wang Qingyao; Yang Xiuchun; Liu Dan; Chi Lina; Hou Junwei

2012-01-01

Highlights: ► Ag and CdS nanoparticles co-sensitized TiO 2 nanotubes were fabricated by the SILAR method. ► The co-sensitization expands the photoresponse range of TiO 2 NTs to 668.7 nm. ► Visible light photocurrents and photocatalytic activities of CdS–Ag/TiO 2 NTs were studied. ► The electron transfer mechanism of CdS–Ag/TiO 2 NTs was proposed. - Abstract: The Ag and CdS nanoparticles co-sensitization of TiO 2 nanotubes (CdS–Ag/TiO 2 NTs) were prepared by successive ionic layer adsorption and reaction (SILAR) technique. The phase composition, morphology and optical property were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis diffusion reflection spectroscopy (DRS). The co-modification of Ag and CdS nanoparticles expanded the photoresponse range of TiO 2 NTs from ultraviolet region to 668.7 nm, and the CdS–Ag/TiO 2 NTs prepared by SILAR deposition of 5 cycles exhibited higher visible photocurrent and stability against photocorrosion. The detailed electrons transfer mechanism of CdS–Ag/TiO 2 NTs was proposed, and photocatalytic activity toward degradation of methyl orange (MO) under visible-light irradiation was also investigated.

Biomimetic Approach to Solar Cells Based on TiO2 Nanotubes

National Research Council Canada - National Science Library

Allen, Jan L; Lee, Ivan C; Wolfenstine, Jeff

2008-01-01

The goal of this research was to explore the use of nanotube titanium dioxide (TiO2) as an electrode material in dye-sensitized solar cells in order to further the development of solar cell technology...

Preparation of Fe-doped TiO{sub 2} nanotube arrays and their photocatalytic activities under visible light

Energy Technology Data Exchange (ETDEWEB)

Tu, Ya-Fang; Huang, Sheng-You [Department of Physics, Wuhan University, Wuhan 430072 (China); Sang, Jian-Ping, E-mail: jpsang@acc-lab.whu.edu.cn [Department of Physics, Wuhan University, Wuhan 430072 (China); Department of Physics, Jianghan University, Wuhan 430056 (China); Zou, Xian-Wu [Department of Physics, Wuhan University, Wuhan 430072 (China)

2010-02-15

Fe-doped TiO{sub 2} nanotube arrays have been prepared by the template-based liquid phase deposition method. Their morphologies, structures and optical properties were investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and UV-vis absorption spectroscopy. Their photocatalytic activities were evaluated by the degradation of methylene blue under visible light. The UV-vis absorption spectra of the Fe-doped TiO{sub 2} nanotube arrays showed a red shift and an enhancement of the absorption in the visible region compared to the undoped sample. The Fe-doped TiO{sub 2} nanotube arrays exhibited good photocatalytic activities under visible light irradiation, and the optimum dopant amount was found to be 5.9 at% in our experiments.

Ag2S/CdS/TiO2 Nanotube Array Films with High Photocurrent Density by Spotting Sample Method

OpenAIRE

Sun, Hong; Zhao, Peini; Zhang, Fanjun; Liu, Yuliang; Hao, Jingcheng

2015-01-01

Ag2S/CdS/TiO2 hybrid nanotube array films (Ag2S/CdS/TNTs) were prepared by selectively depositing a narrow-gap semiconductor—Ag2S (0.9 eV) quantum dots (QDs)—in the local domain of the CdS/TiO2 nanotube array films by spotting sample method (SSM). The improvement of sunlight absorption ability and photocurrent density of titanium dioxide (TiO2) nanotube array films (TNTs) which were obtained by anodic oxidation method was realized because of modifying semiconductor QDs. The CdS/TNTs, Ag2S/TNT...

Synthesis and photocatalytic properties of Sn-doped TiO{sub 2} nanotube arrays

Energy Technology Data Exchange (ETDEWEB)

Tu Yafang; Huang Shengyou [Department of Physics, Wuhan University, Wuhan 430072 (China); Sang Jianping, E-mail: jpsang@acc-lab.whu.edu.c [Department of Physics, Wuhan University, Wuhan 430072 (China); Department of Physics, Jianghan University, Wuhan 430056 (China); Zou Xianwu [Department of Physics, Wuhan University, Wuhan 430072 (China)

2009-08-12

TiO{sub 2} nanotube arrays doped by Sn up to 12 at% have been prepared using template-based liquid phase deposition method. Their morphologies, structures and optical properties have been investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV-vis absorption spectroscopy and photoluminescence spectroscopy. The photocatalytic properties of the samples were evaluated with the degradation of methylene blue under UV irradiation. The result shows that doping an appropriate amount of Sn can effectively improve the photocatalytic activity of TiO{sub 2} nanotube arrays, and the optimum dopant amount is found to be 5.6 at% in our experiments.

Formation and Morphology Evolution of Anodic TiO2 Nanotubes under Negative Pressure

International Nuclear Information System (INIS)

Lu, Hongyan; Fan, Haowen; Jin, Rong; Chong, Bin; Shen, Xiaoping; Yan, Shuo; Zhu, Xufei

2016-01-01

Highlights: • Nernst equation is applied to explain electrochemical reactions during anodization. • Longer nanotubes were obtained under 0.02 MPa, as compared to atmospheric conditions. • The total anodizing current was separated into ionic current and electronic current. • Explanation for the particularity of nanotubes obtained under 0.02 MPa is presented. - Abstract: Anodic TiO 2 nanotubes (ATNTs) have attracted extensive interest in the past decade. ATNTs are generally fabricated by anodization of Ti foils under atmospheric conditions (0.1 MPa). To date, the growth kinetics of ATNTs remains unclear. Herein anodizations of Ti foils under negative pressure are designed to overcome this challenge. Longer nanotubes were fabricated under negative pressure, as compared to atmospheric conditions. Variations of the nanotube length and surface morphology of ATNTs provide evidences for oxygen bubble mould, in which the ionic current contributes to nanotube growth while the electronic current gives rise to the oxygen evolution. Nernst equation was firstly applied to simulate variations of electronic current and ionic current during anodization. The in-depth analysis of the morphology variations could help elucidate the formation mechanism, thus paving the way for the optimization of the synthesis process of ATNTs.

Role of doping and CuO segregation in improving the giant permittivity of CaCu3Ti4O12

International Nuclear Information System (INIS)

Capsoni, D.; Bini, M.; Massarotti, V.; Chiodelli, G.; Mozzatic, M.C.; Azzoni, C.B.

2004-01-01

The dopant role on the electric and dielectric properties of the perovskite-type CaCu 3 Ti 4 O 12 (CCTO) compound is evidenced. Impedance spectroscopy measurements show that the relevant permittivity value attributed to sintered CCTO is due to grain boundary (g.b.) effects. The g.b. permittivity value of the pure CCTO can be increased of 1-2 orders of magnitude by cation substitution on Ti site and/or segregation of CuO phase, while the bulk permittivity keeps values 90εr180. Bulk and g.b. conductivity contributions are discussed: electrons are responsible for the charge transport and a mean bulk activation energy of 0.07eV is obtained at room temperature for all the examined samples. The g.b. activation energy ranges between 0.54 and 0.76eV. Defect models related to the transport properties are proposed, supported by electron paramagnetic resonance measurements

TiO2 Nanotubes: Recent Advances in Synthesis and Gas Sensing Properties

Directory of Open Access Journals (Sweden)

Giorgio Sberveglieri

2013-10-01

Full Text Available Synthesis—particularly by electrochemical anodization-, growth mechanism and chemical sensing properties of pure, doped and mixed titania tubular arrays are reviewed. The first part deals on how anodization parameters affect the size, shape and morphology of titania nanotubes. In the second part fabrication of sensing devices based on titania nanotubes is presented, together with their most notable gas sensing performances. Doping largely improves conductivity and enhances gas sensing performances of TiO2 nanotubes

Multi-walled carbon nanotubes functionalized by carboxylic groups: Activation of TiO{sub 2} (anatase) and phosphate olivines (LiMnPO{sub 4}; LiFePO{sub 4}) for electrochemical Li-storage

Energy Technology Data Exchange (ETDEWEB)

Kavan, Ladislav; Zukalova, Marketa [J. Heyrovsky Institute of Physical Chemistry, v.v.i., Academy of Sciences of the Czech Republic, Dolejskova 3, CZ-18223 Prague 8 (Czech Republic); Bacsa, Revathi; Tunckol, Meltem; Serp, Philippe [Laboratoire de Chimie de Coordination, UPR CNRS 8241, composante ENSIACET, Universite de Toulouse UPS-INP-LCC 4, Allee Emile Monso, BP 74233, 31432, Toulouse (France); Zakeeruddin, Shaik M.; Le Formal, Florian; Graetzel, Michael [Laboratoire de Photonique et Interfaces, EPFL, Ecublens, CH-1015 Lausanne (Switzerland)

2010-08-15

Multi-walled carbon nanotubes functionalized by carboxylic groups, exhibit better affinity towards TiO{sub 2} (P90, Degussa) as compared to that of pristine nanotubes. Also the electrochemical performance of TiO{sub 2} is improved by nanotube networking, but the Li-storage capacity of TiO{sub 2} is unchanged. Whereas the composite of TiO{sub 2} with non-functionalized nanotubes demonstrates simple superposition of the behavior of pure components, the composite with functionalized nanotubes shows unique faradaic pseudocapacitance which is specific for this composite only. The surface functionalization of nanotubes enhances charge storage capacity and reversibility of a composite with LiMnPO{sub 4} (olivine), but mediates also the electrolyte breakdown at potentials >4.2 V. Whereas the electrochemical activation of LiMnPO{sub 4} (olivine) by functionalized nanotubes is quite modest, excellent performance was found for LiFePO{sub 4} (olivine) in composite materials containing only 2 wt% of functionalized nanotubes. (author)

Investigation of anodic TiO2 nanotube composition with high spatial resolution AES and ToF SIMS

Science.gov (United States)

Dronov, Alexey; Gavrilin, Ilya; Kirilenko, Elena; Dronova, Daria; Gavrilov, Sergey

2018-03-01

High resolution Scanning Auger Electron Spectroscopy (AES) and Time-of-Flight Secondary Ion Mass-Spectrometry (ToF SIMS) were used to investigate structure and elemental composition variation of both across an array of TiO2 nanotubes (NTs) and single tube of an array. The TiO2 NT array was grown by anodic oxidation of Ti foil in fluorine-containing ethylene glycol electrolyte. It was found that the studied anodic TiO2 nanotubes have a layered structure with rather sharp interfaces. The differences in AES depth profiling results of a single tube with the focused primary electron beam (point analysis) and over an area of 75 μm in diameter of a nanotube array with the defocused primary electron beam are discussed. Depth profiling by ToF SIMS was carried out over approximately the same size of a nanotube array to determine possible ionic fragments in the structure. The analysis results show that the combination of both mentioned methods is useful for a detailed analysis of nanostructures with complex morphology and multi-layered nature.

Fabrication and characterization of composite TiO{sub 2} nanotubes/boron-doped diamond electrodes towards enhanced supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Sobaszek, M. [Department of Metrology and Optoelectronics, Faculty of Electronics, Telecommunications and Informatics, Gdańsk University of Technology, 11/12 G. Narutowicza St., 80-233 Gdańsk (Poland); Siuzdak, K.; Sawczak, M. [Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, 14 Fiszera St., 80-231 Gdansk (Poland); Ryl, J. [Department of Electrochemistry, Corrosion and Material Engineering, Faculty of Chemistry, Gdańsk University of Technology, 11/12 G. Narutowicza St., 80-233 Gdańsk (Poland); Bogdanowicz, R., E-mail: rbogdan@eti.pg.gda.pl [Department of Metrology and Optoelectronics, Faculty of Electronics, Telecommunications and Informatics, Gdańsk University of Technology, 11/12 G. Narutowicza St., 80-233 Gdańsk (Poland)

2016-02-29

The composite TiO{sub 2} nanotubes/boron-doped diamond electrodes were deposited using Microwave Plasma Enhanced Chemical Vapor Deposition resulting in the improved electrochemical performance. This composite electrode can deliver high specific capacitance of 7.46 mF cm{sup −2} comparing to boron-doped diamond (BDD) deposited onto flat Ti plate (0.11 mF cm{sup −2}).The morphology and composition of composite electrode were characterized by scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) techniques. According to XPS and Raman analyses, the structure of TiO{sub 2} was greatly changed during Chemical Vapor Deposition process: formation of Ti{sup 3+} sites, partial anatase to rutile transformation and titanium carbide phase formation. This effect is attributed to the simultaneous presence of activated hydrogen and carbon in the plasma leading to enhanced dehydration of NTs (nanotubes) followed by carbon bonding. The enhanced capacitive effect of TiO{sub 2} NT/BDD could be recognized as: (1) the unique synergistic morphology of NTs and BDD providing more efficient conducting pathway for the diffusion of ions and (2) partial decomposition of NTs and transformation towards to TiC and Ti{sub 2}O{sub 3} fractions. Finally, highly ordered titania nanotubes produced via simply, quick and controllable method — anodization, could act as promising substrate for conductive BDD layer deposition and further application of such composites for supercapacitor construction. - Highlights: • The TiO{sub 2} nanotube (NT)/diamond electrode delivers capacitance of 7.46 mF cm{sup −2}. • The NTs are not affected by diamond growth process and keep their pristine shape. • The BDD overlayer fully encapsulates TiO{sub 2} NTs exhibiting typical columnar growth. • The activated hydrogen and carbon in the plasma lead to enhanced dehydration of NTs. • The presence of TiC and Ti{sub 2}O{sub 3} fractions introducing additional capacitance.

A visible-light-driven composite photocatalyst of TiO2 nanotube arrays and graphene quantum dots

Directory of Open Access Journals (Sweden)

Donald K. L. Chan

2014-05-01

Full Text Available TiO2 nanotube arrays are well-known efficient UV-driven photocatalysts. The incorporation of graphene quantum dots could extend the photo-response of the nanotubes to the visible-light range. Graphene quantum dot-sensitized TiO2 nanotube arrays were synthesized by covalently coupling these two materials. The product was characterized by Fourier-transform infrared spectrometry (FTIR, scanning electron microscopy (SEM, transmission electron microscopy (TEM, X-ray diffraction (XRD, thermogravimetric analysis (TGA and UV–vis absorption spectroscopy. The product exhibited high photocatalytic performance in the photodegradation of methylene blue and enhanced photocurrent under visible light irradiation.

Hydrothermal fabrication of Ni{sub 3}S{sub 2}/TiO{sub 2} nanotube composite films on Ni anode and application in photoassisted water electrolysis

Energy Technology Data Exchange (ETDEWEB)

He, Hongbo; Chen, Aiping, E-mail: apchen@ecust.edu.cn; Lv, Hui; Dong, Haijun; Chang, Ming; Li, Chunzhong

2013-10-15

Highlights: •Ni{sub 3}S{sub 2}/TiO{sub 2} nanotube photocatalysts were synthesized on Ni by hydrothermal method. •Structure of Ni{sub 3}S{sub 2} wrapped by TiO{sub 2} nanotubes improves remarkably stability of Ni{sub 3}S{sub 2}. •Ni{sub 3}S{sub 2}/TiO{sub 2} film on Ni has better H{sub 2} production performance than TiO{sub 2}-modified anode. -- Abstract: Nanostructured films of rhombohedral Ni{sub 3}S{sub 2} were hydrothermally synthesized on Ni and TiO{sub 2} nanotube layer, as substrates. A possible mechanism is proposed to explain the formation of rhombohedral Ni{sub 3}S{sub 2} nanostructures. The results of UV–vis spectrophotometric studies indicate that optical absorption spectrum of Ni{sub 3}S{sub 2}/TiO{sub 2} nanotube composites could be extended to the visible region. As-synthesized Ni{sub 3}S{sub 2}/TiO{sub 2} nanotube composite films on Ni substrate had better (by about 40%) hydrogen production performance under the visible light irradiation, in comparison with the Ni anode modified by TiO{sub 2} nanotubes.

Efficient solar light-driven degradation of Congo red with novel Cu-loaded Fe3O4@TiO2 nanoparticles.

Science.gov (United States)

Arora, Priya; Fermah, Alisha; Rajput, Jaspreet Kaur; Singh, Harminder; Badhan, Jigyasa

2017-08-01

In this work, Cu-loaded Fe 3 O 4 @TiO 2 core shell nanoparticles were prepared in a single pot by coating of TiO 2 on Fe 3 O 4 nanoparticles followed by Cu loading. X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), thermogravimetric analysis (TGA), Brunauer-Emmett- Teller (BET), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS), and valence band X-ray photoelectron spectroscopy (VB XPS) techniques were used for characterization of as prepared nanoparticles. Synergism between copper and titania was evaluated by studying the solar light-driven photodegradation of Congo red dye solution in the presence of Fe 3 O 4 @TiO 2 nanoparticles on one side and Cu-loaded Fe 3 O 4 @TiO 2 nanoparticles on the other side. The latter performed better than the former catalyst, indicating the enhanced activity of copper-loaded catalyst. Further photodegradation was studied by three means, i.e., under ultraviolet (UV), refluxing, and solar radiations. Cu-loaded Fe 3 O 4 @TiO 2 enhanced the degradation efficiency of Congo red dye. Thus, Cu act possibly by reducing the band gap of TiO 2 and widening the optical response of semiconductor, as a result of which solar light could be used to carry out photocatalysis. Graphical abstract Photodegradation of congo red over Cu-loaded Fe 3 O 4 @TiO 2 nanoparticles.

Improved resistive switching phenomena and mechanism using Cu-Al alloy in a new Cu:AlO{sub x}/TaO{sub x}/TiN structure

Energy Technology Data Exchange (ETDEWEB)

Roy, S. [Thin Film Nano Tech. Lab., Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kwei-Shan, Tao-Yuan 333, Taiwan (China); Maikap, S., E-mail: sidhu@mail.cgu.edu.tw [Thin Film Nano Tech. Lab., Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kwei-Shan, Tao-Yuan 333, Taiwan (China); Sreekanth, G.; Dutta, M.; Jana, D. [Thin Film Nano Tech. Lab., Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kwei-Shan, Tao-Yuan 333, Taiwan (China); Chen, Y.Y.; Yang, J.R. [Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan (China)

2015-07-15

Highlights: • Cu:AlO{sub x} alloy is used for the first time to have defective TaO{sub x} film. • A relation in between formation voltage and RESET current has been developed. • A switching mechanism based on a thinner with dense Cu filament is demonstrated. • Good uniformity with yield of >90% and long cycles using 1 ms pulse are obtained. - Abstract: Improved resistive switching phenomena such as device-to-device uniformity, lower formation voltage (2.8 V) and RESET current, >500 program/erase cycles, longer read endurance of >10{sup 6} cycles with a program/erase pulse width of 1 μs, and data retention of >225 h under a low current compliance of 300 μA have been discussed by using Cu-Al alloy in Cu:AlO{sub x}/TaO{sub x}/TiN conductive bridging resistive random access memory (CBRAM) device for the first time. The switching mechanism is based on a thinner with dense Cu filament formation/dissolution through the defects in the Cu:AlO{sub x}/TaO{sub x}/TiN structure owing to enhance memory characteristics. These characteristics have been confirmed by measuring randomly picked 100 devices having via-hole size of 0.4 × 0.4 μm{sup 2}. The Cu-Al alloy becomes Cu:AlO{sub x} buffer layer and Ta{sub 2}O{sub 5} becomes TaO{sub x} switching layer owing to Gibbs free energy dependency. All layers and elements are observed by high-resolution transmission electron microscope (HRTEM) image and energy dispersive X-ray spectroscopy (EDX). By developing a numerical equation in between RESET current and formation voltage, it is found that a higher rate of Cu migration is observed owing to both the defective switching layer and larger size, which results a lower formation voltage and RESET current of the Cu:AlO{sub x}/TaO{sub x}/TiN structure, as compared to Cu/Ta{sub 2}O{sub 5}/TiN under external positive bias on the Cu electrode. This simple Cu:AlO{sub x}/TaO{sub x}/TiN CBRAM device is useful for future nanoscale non-volatile memory application.

Ternary CNTs@TiO₂/CoO Nanotube Composites: Improved Anode Materials for High Performance Lithium Ion Batteries.

Science.gov (United States)

Madian, Mahmoud; Ummethala, Raghunandan; Naga, Ahmed Osama Abo El; Ismail, Nahla; Rümmeli, Mark Hermann; Eychmüller, Alexander; Giebeler, Lars

2017-06-20

TiO₂ nanotubes (NTs) synthesized by electrochemical anodization are discussed as very promising anodes for lithium ion batteries, owing to their high structural stability, high surface area, safety, and low production cost. However, their poor electronic conductivity and low Li⁺ ion diffusivity are the main drawbacks that prevent them from achieving high electrochemical performance. Herein, we report the fabrication of a novel ternary carbon nanotubes (CNTs)@TiO₂/CoO nanotubes composite by a two-step synthesis method. The preparation includes an initial anodic fabrication of well-ordered TiO₂/CoO NTs from a Ti-Co alloy, followed by growing of CNTs horizontally on the top of the oxide films using a simple spray pyrolysis technique. The unique 1D structure of such a hybrid nanostructure with the inclusion of CNTs demonstrates significantly enhanced areal capacity and rate performances compared to pure TiO₂ and TiO₂/CoO NTs, without CNTs tested under identical conditions. The findings reveal that CNTs provide a highly conductive network that improves Li⁺ ion diffusivity, promoting a strongly favored lithium insertion into the TiO₂/CoO NT framework, and hence resulting in high capacity and an extremely reproducible high rate capability.

Distinguishing between deep trapping transients of electrons and holes in TiO2 nanotube arrays using planar microwave resonator sensor.

Science.gov (United States)

Zarifi, Mohammad H; Wiltshire, Benjamin Daniel; Mahdi, Najia; Shankar, Karthik; Daneshmand, Mojgan

2018-05-16

A large signal DC bias and a small signal microwave bias were simultaneously applied to TiO2 nanotube membranes mounted on a planar microwave resonator. The DC bias modulated the electron concentration in the TiO2 nanotubes, and was varied between 0 and 120 V in this study. Transients immediately following the application and removal of DC bias were measured by monitoring the S-parameters of the resonator as a function of time. The DC bias stimulated Poole-Frenkel type trap-mediated electrical injection of excess carriers into TiO2 nanotubes which resulted in a near constant resonant frequency but a pronounced decrease in the microwave amplitude due to free electron absorption. When ultraviolet illumination and DC bias were both present and then step-wise removed, the resonant frequency shifted due to trapping -mediated change in the dielectric constant of the nanotube membranes. Characteristic lifetimes of 60-80 s, 300-800 s and ~3000 s were present regardless of whether light or bias was applied and are also observed in the presence of a hole scavenger, which we attribute to oxygen adsorption and deep electron traps while another characteristic lifetime > 9000 s was only present when illumination was applied, and is attributed to the presence of hole traps.

Synthesis of self-organized TiO{sub 2} nanotube arrays: Microstructural, stereoscopic, and topographic studies

Energy Technology Data Exchange (ETDEWEB)

Quiroz, Heiddy P., E-mail: hpquirozg@unal.edu.co; Dussan, A., E-mail: adussanc@unal.edu.co [Department of Physis, Grupo de Materiales Nanoestructurados y sus Aplicaciones, Universidad Nacional de Colombia, Bogotá 11001 (Colombia)

2016-08-07

In this work, titanium dioxide nanotubes were prepared by using titanium foils via electrochemical anodization in ethylene glycol solutions containing different amounts of water and fluoride in the ranges of 1%–3% and 0.15%–0.5%, respectively, to determine their effects on morphology, optical, and crystalline structure properties. Annealing processes were performed on all samples in the range between 273 and 723 K. Morphology and structure properties of the samples were studied by scanning electron microscopy, X-ray diffraction (XRD), and transmission electron microscopy. Titanium dioxide (TiO{sub 2}) nanotubes, through anodization method, are strongly influenced by conditions, like fluoride concentration and applied voltages. Tube lengths between 2 and 7 μm were obtained, exhibiting different diameters and wall thicknesses. When alternating voltage was applied, the outer surface of the nanotubes exhibited evenly spaced ring-shaped regions, while smooth tubes were observed when constant voltage was applied. Reflection peaks, corresponding to Brookite, Anatase, and Rutile, of TiO{sub 2} phases, were observed from the XRD pattern. These phases were corroborated via μXRD measurements, and the Ti{sub 3}O{sub 5} phase was also observed in detail. Absorption coefficient (α), optical band gap (Eg), and extinction coefficient (ε) of TiO{sub 2} nanotubes were calculated by transmittance spectra in the UV–Vis range. Strong absorption was noted in the UV region from reflectance and absorbance measurements. A correlation between synthesis parameters and physical properties is presented.

Study of the highly ordered TiO2 nanotubes physical properties prepared with two-step anodization

Science.gov (United States)

Pishkar, Negin; Ghoranneviss, Mahmood; Ghorannevis, Zohreh; Akbari, Hossein

2018-06-01

Highly ordered hexagonal closely packed titanium dioxide nanotubes (TiO2 NTs) were successfully grown by a two-step anodization process. The TiO2 NTs were synthesized by electrochemical anodization of titanium foils in an ethylene glycol based electrolyte solution containing 0.3 wt% NH4F and 2 vol% deionized (DI) water at constant potential (50 V) for 1 h at room temperature. Physical properties of the TiO2 NTs, which were prepared via one and two-step anodization, were investigated. Atomic Force Microscopy (AFM) analysis revealed that anodization and subsequently peeled off the TiO2 NTs caused to the periodic pattern on the Ti surface. In order To study the nanotubes morphology, Field Emission Scanning Electron Microscopy (FESEM) was used, which was revealed that the two-step anodization resulted highly ordered hexagonal TiO2 NTs. Crystal structures of the TiO2 NTs were mainly anatase, determined by X-ray diffraction analysis. Optical studies were performed by Diffuse Reflection Spectra (DRS) and Photoluminescence (PL) analysis showed that the band gap of TiO2 NTs prepared via two-step anodization was lower than the band gap of samples prepared by one-step anodization process.

A Facile Method for Loading CeO2 Nanoparticles on Anodic TiO2 Nanotube Arrays.

Science.gov (United States)

Liao, Yulong; Yuan, Botao; Zhang, Dainan; Wang, Xiaoyi; Li, Yuanxun; Wen, Qiye; Zhang, Huaiwu; Zhong, Zhiyong

2018-04-03

In this paper, a facile method was proposed to load CeO 2 nanoparticles (NPs) on anodic TiO 2 nanotube (NT) arrays, which leads to a formation of CeO 2 /TiO 2 heterojunctions. Highly ordered anatase phase TiO 2 NT arrays were fabricated by using anodic oxidation method, then these individual TiO 2 NTs were used as tiny "nano-containers" to load a small amount of Ce(NO 3 ) 3 solutions. The loaded anodic TiO 2 NTs were baked and heated to a high temperature of 450 °C, under which the Ce(NO 3 ) 3 would be thermally decomposed inside those nano-containers. After the thermal decomposition of Ce(NO 3 ) 3 , cubic crystal CeO 2 NPs were obtained and successfully loaded into the anodic TiO 2 NT arrays. The prepared CeO 2 /TiO 2 heterojunction structures were characterized by a variety of analytical technologies, including XRD, SEM, and Raman spectra. This study provides a facile approach to prepare CeO 2 /TiO 2 films, which could be very useful for environmental and energy-related areas.

Crystal structure and ferroelectric properties of Ca(Cu3−xMx)Ti4O12 (M = Fe and Ni) ceramics

International Nuclear Information System (INIS)

Moriyama, Tohru; Kan, Akinori; Ogawa, Hirotaka

2013-01-01

Highlights: ► M-substituted Ca(Cu 3−x M x )Ti 4 O 12 (CCMTO) ceramics, where M = Fe and Ni, were synthesized. ► The influence of M substitution for Cu on crystal structure and ferroelectric properties of CCMTO ceramics were investigated. ► Analysis of CCMTO ceramics revealed the single phase of CCMTO ceramics belongs to I23 non-centrosymmetric space group of I23. ► As a result, the P r and E c values of CCFTO ceramics at x = 0.05 were 1.8 μC/cm 2 and 40 kV/cm, respectively. -- Abstract: M-substituted Ca(Cu 3−x M x )Ti 4 O 12 (CCMTO) ceramics, where M = Fe and Ni, were synthesized and the influence of M substitutions for Cu on the crystal structure and ferroelectric properties of CCMTO ceramics were investigated in this study. From the variations in the lattice parameters of CCMTO ceramics, the solubility limit of Ni substitution for Cu in CaCu 3−x Ni x Ti 4 O 12 (CCNTO) ceramics was x = 0.2, whereas that of CaCu 3−x Fe x Ti 4 O 12 (CCFTO) ceramics was x = 0.05. The crystal structural analysis of CCMTO ceramics revealed that the single phase of CCMTO ceramics belongs to the I23 non-centrosymmetric space group of I23; as a result, the P r and E c values of CCFTO ceramics at x = 0.05 were 1.8 μC/cm 2 and 40 kV/cm, respectively. The ferroelectric behavior of CCMTO ceramics by the M substitutions for Cu may be related to the displacement of a Ti 4+ cation in the TiO 6 octahedra and tilting of the Ti–O–Ti angle because of the non-centrosymmetric space group

Asymmetric photoelectric property of transparent TiO{sub 2} nanotube films loaded with Au nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Wang, Hui [College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China); College of Applied Science, Taiyuan University of Science and Technology, Taiyuan, Shanxi 030024 (China); Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Ministry of Education, Taiyuan, Shanxi 030024 (China); Liang, Wei, E-mail: 986903124@qq.com [College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China); Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Ministry of Education, Taiyuan, Shanxi 030024 (China); Liu, Yiming; Zhang, Wanggang; Zhou, Diaoyu; Wen, Jing [College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China); Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Ministry of Education, Taiyuan, Shanxi 030024 (China)

2016-11-15

Highlights: • Highly transparent films of TiO{sub 2} nanotube arrays were directly fabricated on FTO glasses. • Semitransparent TNT-Au composite films were obtained and exhibited excellent photoelectrocatalytic ability. • Back-side of TNT-Au composite films was firstly irradiated and tested to compare with front-side of films. - Abstract: Semitransparent composite films of Au loaded TiO{sub 2} nanotubes (TNT-Au) were prepared by sputtering Au nanoparticles on highly transparent TiO{sub 2} nanotubes films, which were fabricated directly on FTO glasses by anodizing the Ti film sputtered on the FTO glasses. Compared with pure TNT films, the prepared TNT-Au films possessed excellent absorption ability and high photocurrent response and improved photocatalytic activity under visible-light irradiation. It could be concluded that Au nanoparticles played important roles in improving the photoelectrochemical performance of TNT-Au films. Moreover, in this work, both sides of TNT-Au films were researched and compared owing to theirs semitransparency. It was firstly found that the photoelectric activity of TNT-Au composite films with back-side illumination was obviously superior to front-side illumination.

Cu{sub 2}O/TiO{sub 2} heterostructures on a DVD as easy&cheap photoelectrochemical sensors

Energy Technology Data Exchange (ETDEWEB)

Zanatta, Michele; Calvillo, Laura; Zheng, Jian; Rizzi, Gian Andrea, E-mail: gianandrea.rizzi@unipd.it; Durante, Christian; Giallongo, Giuseppe; Chirkov, Dymitrov; Colazzo, Luciano; Marega, Carla; Gennaro, Armando; Granozzi, Gaetano

2016-03-31

Cu{sub 2}O nanoparticles have been grown by pulse-electrochemical deposition on a Digital Versatile Disk (DVD) which acts as a nanostructured electrode. Prior to Cu{sub 2}O deposition, the silver-coated rectangular-shaped grooves of the disassembled DVD were coated with a TiO{sub 2} thin film by a modified sol–gel method, where oxalic acid is used in place of the usual mineral acids to peptize the precipitated hydrous titania formed from the hydrolysis of titanium iso-propoxide. This procedure leaves no inorganic residues after UV-curing, resulting in a high quality film, mainly composed of TiO{sub 2}-anatase. As demonstrated by Atomic Force Microscopy (AFM) measurements, the DVD grooves are filled by a 120–130 nm thick TiO{sub 2} film, while the thickness of the TiO{sub 2} deposit on the crests is only ca. 50 nm. This inhomogeneous thickness leads to an inhomogeneous electric field when the DVD is used as an electrode for depositing Cu{sub 2}O nanoparticles, which eventually leads to the growth of Cu{sub 2}O nanoparticles only on the DVD crests. A highly regular and reproducible Cu{sub 2}O/TiO{sub 2} stripe-like heterostructure is obtained where both semiconducting oxides are aside. This system has been characterized by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), X-ray photoemission spectroscopy (XPS), Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy, Raman spectroscopy and photocurrent measurements. A possible use of this easy&cheap electrode as a visible light responsive sensor to water soluble organics in basic solution is suggested. - Highlights: • A commercial DVD is recycled to prepare cheap photo-electrochemical sensors. • The sensing elements are Cu{sub 2}O nanostripes grown on a nanostructured TiO{sub 2} thin film obtained at room temperature. • Water soluble organics can be detected by dissolved O{sub 2} activation with visible light.

Chemical solution deposition of CaCu3Ti4O12 thin film

Indian Academy of Sciences (India)

Administrator

CaCu3Ti4O12; thin film; chemical solution deposition; dielectric properties. 1. Introduction. The CaCu3Ti4O12. (CCTO) compound has recently attracted considerable ... and Kelvin probe force microscopy (Chung et al 2004). Intrinsic .... SEM images of CCTO thin films as a function of sintering temperature. silicon based ...

Dominant factors governing the rate capability of a TiO2 nanotube anode for high power lithium ion batteries.

Science.gov (United States)

Han, Hyungkyu; Song, Taeseup; Lee, Eung-Kwan; Devadoss, Anitha; Jeon, Yeryung; Ha, Jaehwan; Chung, Yong-Chae; Choi, Young-Min; Jung, Yeon-Gil; Paik, Ungyu

2012-09-25

Titanium dioxide (TiO(2)) is one of the most promising anode materials for lithium ion batteries due to low cost and structural stability during Li insertion/extraction. However, its poor rate capability limits its practical use. Although various approaches have been explored to overcome this problem, previous reports have mainly focused on the enhancement of both the electronic conductivity and the kinetic associated with lithium in the composite film of active material/conducting agent/binder. Here, we systematically explore the effect of the contact resistance between a current collector and a composite film of active material/conducting agent/binder on the rate capability of a TiO(2)-based electrode. The vertically aligned TiO(2) nanotubes arrays, directly grown on the current collector, with sealed cap and unsealed cap, and conventional randomly oriented TiO(2) nanotubes electrodes were prepared for this study. The vertically aligned TiO(2) nanotubes array electrode with unsealed cap showed superior performance with six times higher capacity at 10 C rate compared to conventional randomly oriented TiO(2) nanotubes electrode with 10 wt % conducting agent. On the basis of the detailed experimental results and associated theoretical analysis, we demonstrate that the reduction of the contact resistance between electrode and current collector plays an important role in improving the electronic conductivity of the overall electrode system.

Preparation of Li4Ti5O12 by solution ion-exchange of sodium titanate nanotube and evaluation of electrochemical performance

International Nuclear Information System (INIS)

Zhang, Jingwei; Zhang, Fenli; Li, Jiuhe; Cai, Wei; Zhang, Jiwei; Yu, Laigui; Jin, Zhensheng; Zhang, Zhijun

2013-01-01

Nano-sized spinel lithium titanate (Li 4 Ti 5 O 12 ) was synthesized using sodium titanate nanotube as precursor via a facile solution ion-exchange method in association with subsequent calcination treatment at relatively low temperature. The influences of precursors, ion-exchange condition, and calcination temperature on the microstructure and electrochemical performance of the products were studied. Results indicate that pure-phase Li 4 Ti 5 O 12 can be harvested from sodium titanate nanotube precursor through an ion-exchanging at room temperature and calcination at 500 °C. The products exhibit a better performance as Li-ion battery anode material than the counterparts prepared from protonic titanate nanotube (H-titanate) precursor. The reason may lie in that sodium titanate nanotube is easier than protonic titanate nanotube to synthesize lithium titanate without TiO 2 impurity, resulting in reduced electron transfer ability and Li-ion transport ability. The capacity of Li 4 Ti 5 O 12 prepared from sodium titanate nanotube is 146 mAh/g at 10 C, and it has only 0.7 % decay after 200 charge/discharge cycles

Modification of TiO(2) nanotube surfaces by electro-spray deposition of amoxicillin combined with PLGA for bactericidal effects at surgical implantation sites.

Science.gov (United States)

Lee, Jung-Hwan; Moon, Seung-Kyun; Kim, Kwang-Mahn; Kim, Kyoung-Nam

2013-01-01

To fabricate the antibiotic-releasing coatings on TiO(2) nanotube surfaces for wide applications of implant and bone plate in medical and dental surgery, the optimal deposition time of amoxicillin/PLGA solution simultaneously performing non-toxicity and a high bactericidal effect for preventing early implant failures was found. FE-SEM, ESD and FT-IR were used for confirming deposition of amoxicillin/PLGA on the TiO(2) surface. Also, the elution of amoxicillin/PLGA in a TiO(2) nanotube surface was measured by a UV-VIS spectrophotometer. The bactericidal effect of amoxicillin on the TiO(2) nanotube surface was evaluated by using Staphylococcus aureus (S. aureus). The cytotoxicity and cell proliferation were observed by WST assay using MC3T3-E1 osteoblast cells. The results indicated that the TiO(2) nanotube surface controlled by electro-spray deposition time with amoxicillin/PLGA solution could provide a high bactericidal effect against S. aureus by the bactericidal effect of amoxicillin, as well as good osteoblast cell proliferation at the TiO(2) nanotube surface without toxicity. This study used electro-spray deposition (ESD) methodology to obtain amoxicillin deposition in nanotube structures of TiO(2) and found the optimal deposition time of amoxicillin/PLGA solution simultaneously performing non-toxicity and a high bactericidal effect for preventing early implant failures.

Room temperature deposition of amorphous p-type CuFeO2 and ...

Indian Academy of Sciences (India)

2Key Lab of Novel Thin Film Solar Cells, Chinese Academy of Sciences, Hefei 230031, China. 3University of Science and Technology of China, Hefei 230026, China. MS received 14 October 2015; accepted 28 December 2015. Abstract. Transparent conducting amorphous p-type CuFeO2 (CFO) thin film was prepared by ...

Synthesis of frost-like CuO combined graphene-TiO{sub 2} by self-assembly method and its high photocatalytic performance

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Dinh Cung Tien [Department of Advanced Materials Science & Engineering, Hanseo University, Seosan, Chungnam, 356-706 (Korea, Republic of); Cho, Kwang-Youn [Korea Institutes of Ceramic Engineering and Technology, Soho-ro, Jinju-Si, Gyeongsangnam-do (Korea, Republic of); Oh, Won-Chun, E-mail: wc_oh@hanseo.ac.kr [Department of Advanced Materials Science & Engineering, Hanseo University, Seosan, Chungnam, 356-706 (Korea, Republic of)

2017-08-01

Highlights: • The frost-like CuO nanoparticles (3–5 nm) combined with the small TiO{sub 2} rods (50–100 nm) are expected to have a high charge transfer effect from TiO{sub 2} to CuO. • In this study, ·OH and h{sup +} play a major role in the photocatalytic reaction than O{sub 2}·{sup –} or both hydroxyl and holes are the active species responsible under visible light irradiation. • The photocatalytic degradation of rhodamine B (RhB), methylene blue trihydrate (MB), and reactive black B (RBB) in an aqueous solution under visible light irradiation was observed by UV spectrophotometry after measurement of the decrease of their concentrations. CuO-graphene-TiO{sub 2} is expected to become a new potential material for photodegradation activity with excellent photodegradation. - Graphical abstract: TEM image of CuO-graphene (a and b), and CuO-graphene-TiO{sub 2} (c and d) composites. - Abstract: A novel material, frost-like CuO combined-graphene-TiO{sub 2} composite, was successfully synthesized using a self-assembly method. During the reaction, the loading of CuO and TiO{sub 2} nanoparticles on graphene sheets was achieved. The obtained CuO-graphene-TiO{sub 2} composite photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), and X-ray photoelectron spectroscopy (XPS). The frost-like CuO nanoparticles combined with the small TiO{sub 2} rods were successfully loaded on the transparent graphene sheets. The photocatalytic degradation of rhodamine B (RhB), methylene blue trihydrate (MB), and reactive black B (RBB) in an aqueous solution under visible light irradiation was observed by UV spectrophotometry after measurement of the decrease of their concentrations. Through the photocatalytic test and TOC results, the CuO-graphene-TiO{sub 2} is expected to

Quantum Chemical Study of Water Adsorption on the Surfaces of SrTiO3 Nanotubes.

Science.gov (United States)

Bandura, Andrei V; Kuruch, Dmitry D; Evarestov, Robert A

2015-07-20

We have studied the adsorption of water molecules on the inner and outer surfaces of nanotubes generated by rolling (001) layers of SrTiO3 cubic crystals. The stability and the atomic and electronic structures of the adsorbed layers are determined by using hybrid density functional theory. The absorption energy and the preferred adsorbate structure are essentially governed by the nature of the surface of the nanotube. Dissociative adsorption prevails on the outer nanotube surfaces. The stability of the adsorbed layers on the inner surfaces is related to the possibility of the formation of hydrogen bonds between water molecules and surface oxygen atoms, and depends on the surface curvature. The presence of water molecules on the inner surface of the nanotubes leads to an increase of the electronic band gap. Externally TiO2 -terminated nanotubes could be used for the photocatalytic decomposition of water by ultraviolet radiation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of Pd-loaded La-doped TiO{sub 2} nanotubes and investigation of their photocatalytic activity under visible light

Energy Technology Data Exchange (ETDEWEB)

Zong, Lanlan; Li, Qiuye, E-mail: qiuyeli@henu.edu.cn; Zhang, Jiwei; Wang, Xiaodong; Yang, Jianjun [Henan University, Key Laboratory for Special Functional Materials (China)

2013-11-15

Orthorhombic titanic acid nanotubes (TAN) have large BET surface area and small-diameter one-dimensional nanotubular morphology, so they can work as a good supporter and a precursor of TiO{sub 2}. However, in our former research, we found that calcination of TAN to anatase TiO{sub 2} would destroy the nanotubular structure and decrease the BET surface area sharply. In this work, we utilized the pillar effect of the foreign nanoparticles (La{sub 2}O{sub 3}) to keep the nanotubular morphology of TiO{sub 2}, and obtained the anatase TiO{sub 2} nanotubes with large BET surface area. For improving the photocatalytic activity, Pd nanoparticles were loaded as the electron traps on the surface of La-doped TiO{sub 2} by photo-deposition method. The photocatalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, diffuse reflectance spectra, and N{sub 2} adsorption–desorption isotherms measurement. Their photocatalytic activities were evaluated by the removal of propylene under visible light irradiation (λ ≥ 420 nm). The results showed that the photocatalytic activity of Pd-loaded La-doped TiO{sub 2} nanotubes improved effectively compared with that of La-doped TiO{sub 2} and pure TiO{sub 2}.

FTIR study of formic acid interaction with TiO2 and TiO2 doped with Pd and Cu in photocatalytic processes

International Nuclear Information System (INIS)

Arana, J.; Garriga i Cabo, C.; Dona-Rodriguez, J.M.; Gonzalez-Diaz, O.; Herrera-Melian, J.A.; Perez-Pena, J.

2004-01-01

In this study the different processes occurring on the TiO 2 and Pd and Cu doped TiO 2 surfaces during the photocatalytic formic acid degradation in the presence or absence of S 2 O 8 2- or H 2 O 2 have been investigated. FTIR studies have shown the relevance of the H-bounded hydroxyl groups. It has been observed that formate molecules interact simultaneously with the dopants and surfacial Ti atoms yielding an intermediate species which plays an important role in the phototacatalytic degradation mechanism. Also, it has been determined that Pd or Cu oxides may act as receptors or transmitters of the TiO 2 photogenerated electrons and thus modify the degradation mechanism. Different redox reactions have been proposed according to the obtained results

Room temperature magnetic and dielectric properties of cobalt doped CaCu3Ti4O12 ceramics

Science.gov (United States)

Mu, Chunhong; Song, Yuanqiang; Wang, Haibin; Wang, Xiaoning

2015-05-01

CaCu3Ti4-xCoxO12 (x = 0, 0.2, 0.4) ceramics were prepared by a conventional solid state reaction, and the effects of cobalt doping on the room temperature magnetic and dielectric properties were investigated. Both X-ray diffraction and energy dispersive X-ray spectroscopy confirmed the presence of Cu and Co rich phase at grain boundaries of Co-doped ceramics. Scanning electron microscopy micrographs of Co-doped samples showed a striking change from regular polyhedral particle type in pure CaCu3Ti4O12 (CCTO) to sheet-like grains with certain growth orientation. Undoped CaCu3Ti4O12 is well known for its colossal dielectric constant in a broad temperature and frequency range. The dielectric constant value was slightly changed by 5 at. % and 10 at. % Co doping, whereas the second relaxation process was clearly separated in low frequency region at room temperature. A multirelaxation mechanism was proposed to be the origin of the colossal dielectric constant. In addition, the permeability spectra measurements indicated Co-doped CCTO with good magnetic properties, showing the initial permeability (μ') as high as 5.5 and low magnetic loss (μ″ < 0.2) below 3 MHz. And the interesting ferromagnetic superexchange coupling in Co-doped CaCu3Ti4O12 was discussed.

Photocathodic Protection of 304 Stainless Steel by Bi2S3/TiO2 Nanotube Films Under Visible Light.

Science.gov (United States)

Li, Hong; Wang, Xiutong; Wei, Qinyi; Hou, Baorong

2017-12-01

We report the preparation of TiO 2 nanotubes coupled with a narrow bandgap semiconductor, i.e., Bi 2 S 3 , to improve the photocathodic protection property of TiO 2 for metals under visible light. Bi 2 S 3 /TiO 2 nanotube films were successfully synthesized using the successive ionic layer adsorption and reaction (SILAR) method. The morphology and structure of the composite films were studied by scanning electron microscopy and X-ray diffraction, respectively. UV-visible diffuse reflectance spectra were recorded to analyze the optical absorption property of the composite films. In addition, the influence of Bi 2 S 3 deposition cycles on the photoelectrochemical and photocathodic protection properties of the composite films was also studied. Results revealed that the heterostructure comprised crystalline anatase TiO 2 and orthorhombic Bi 2 S 3 and exhibited a high visible light response. The photocurrent density of Bi 2 S 3 /TiO 2 was significantly higher than that of pure TiO 2 under visible light. The sensitization of Bi 2 S 3 enhanced the separation efficiency of the photogenerated charges and photocathodic protection properties of TiO 2 . The Bi 2 S 3 /TiO 2 nanotubes prepared by SILAR deposition with 20 cycles exhibited the optimal photogenerated cathodic protection performance on the 304 stainless steel under visible light.

Photocathodic Protection of 304 Stainless Steel by Bi2S3/TiO2 Nanotube Films Under Visible Light

Science.gov (United States)

Li, Hong; Wang, Xiutong; Wei, Qinyi; Hou, Baorong

2017-01-01

We report the preparation of TiO2 nanotubes coupled with a narrow bandgap semiconductor, i.e., Bi2S3, to improve the photocathodic protection property of TiO2 for metals under visible light. Bi2S3/TiO2 nanotube films were successfully synthesized using the successive ionic layer adsorption and reaction (SILAR) method. The morphology and structure of the composite films were studied by scanning electron microscopy and X-ray diffraction, respectively. UV-visible diffuse reflectance spectra were recorded to analyze the optical absorption property of the composite films. In addition, the influence of Bi2S3 deposition cycles on the photoelectrochemical and photocathodic protection properties of the composite films was also studied. Results revealed that the heterostructure comprised crystalline anatase TiO2 and orthorhombic Bi2S3 and exhibited a high visible light response. The photocurrent density of Bi2S3/TiO2 was significantly higher than that of pure TiO2 under visible light. The sensitization of Bi2S3 enhanced the separation efficiency of the photogenerated charges and photocathodic protection properties of TiO2. The Bi2S3/TiO2 nanotubes prepared by SILAR deposition with 20 cycles exhibited the optimal photogenerated cathodic protection performance on the 304 stainless steel under visible light.

Transforming n=1 members of the Ruddlesden-Popper phases to a n=3 member through metathesis: synthesis of a new layered perovskite, Ca2La2CuTi2O10

International Nuclear Information System (INIS)

Sivakumar, T.; Lofland, S.E.; Ramanujachary, K.V.; Ramesha, K.; Subbanna, G.N.; Gopalakrishnan, J.

2004-01-01

We report the formation of a new n=3 Ruddlesden-Popper (R-P) layered perovskite oxide, Ca 2 La 2 CuTi 2 O 10 (I), in the metathesis reaction between NaLaTiO 4 and Ca 2 CuO 2 Cl 2 (n=1 R-P phases) at 700 deg. C in air. Rietveld refinement of powder XRD data shows that I is isostructural with Sr 4 Ti 3 O 10 (space group I4/mmm; a=3.8837(5), c=27.727(6) A), consisting of triple perovskite CuTi 2 O 10 sheets wherein Cu and Ti are ordered at the central and terminal octahedral sites, respectively. Magnetization data provide support for the presence of strong antiferromagnetically coupled CuO 2 sheets in the structure. I is metastable decomposing at higher temperatures (∼950 deg. C) to a mixture of perovskite-like CaLa 2 CuTi 2 O 9 and CaO. Interestingly, the reaction between NaLaTiO 4 and Sr 2 CuO 2 Cl 2 follows a different metathesis route, 2NaLaTiO 4 +Sr 2 CuO 2 Cl 2 →La 2 CuO 4 +2SrTiO 3 +2NaCl, revealing multiplicity of reaction pathways for solid-state metathesis reactions

Study on photocatalysis of TiO2 nanotubes prepared by methanol ...

Indian Academy of Sciences (India)

TiO2 nanotubes were synthesized by the solvothermal process at low temperature in a highly alkaline water–methanol mixed solution. Their characteristics were identified by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), specific surface area (BET), Fourier transform infrared spectroscopy (FTIR) ...

Fabrication of 3D interconnected porous TiO{sub 2} nanotubes templated by poly(vinyl chloride-g-4-vinyl pyridine) for dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Koh, Joo Hwan; Koh, Jong Kwan; Seo, Jin Ah; Kim, Jong Hak [Department of Chemical and Biomolecular Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Shin, Jong-Shik, E-mail: jonghak@yonsei.ac.kr [Department of Biotechnology, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)

2011-09-07

Porous TiO{sub 2} nanotube arrays with three-dimensional (3D) interconnectivity were prepared using a sol-gel process assisted by poly(vinyl chloride-graft-4-vinyl pyridine), PVC-g-P4VP graft copolymer and a ZnO nanorod template. A 7 {mu}m long ZnO nanorod array was grown from the fluorine-doped tin oxide (FTO) glass via a liquid phase deposition method. The TiO{sub 2} sol-gel solution templated by the PVC-g-P4VP graft copolymer produced a random 3D interconnection between the adjacent ZnO nanorods during spin coating. Upon etching of ZnO, TiO{sub 2} nanotubes consisting of 10-15 nm nanoparticles were generated, as confirmed by wide-angle x-ray scattering (WAXS), energy-filtering transmission electron microscopy (EF-TEM) and field-emission scanning electron microscopy (FE-SEM). The ordered and interconnected nanotube architecture showed an enhanced light scattering effect and increased penetration of polymer electrolytes in dye-sensitized solar cells (DSSC). The energy conversion efficiency reached 1.82% for liquid electrolyte, and 1.46% for low molecular weight (M{sub w}) and 0.74% for high M{sub w} polymer electrolytes.

Relationship between the electrochemical behavior of multiwalled carbon nanotubes (MWNTs) loaded with CuO and the photocatalytic activity of Eosin Y-MWNTs-CuO system

Science.gov (United States)

Bui, Duc-Nguyen; Kang, Shi-Zhao; Qin, Lixia; Li, Xiang-Qing; Mu, Jin

2013-02-01

The photocatalytic system containing Eosin Y, multiwalled carbon nanotubes (MWNTs) and CuO (Eosin Y-MWNTs-CuO) was fabricated; meanwhile its photocatalytic activity for hydrogen evolution from triethanolamine (TEOA) aqueous solution was evaluated. Under visible light irradiation, the amount of hydrogen (H2) evolution increased greatly due to introduction of CuO in the photocatalytic system. Moreover, the electrochemical behavior of MWNTs loaded with CuO was explored using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results clearly indicate that there is a strong relationship between the electrochemical behavior of MWNTs-CuO and the photocatalytic activity of Eosin Y-MWNTs-CuO, and the high photocatalytic activity of Eosin Y-MWNTs-CuO may mainly originate from the efficient electron-transfer in the system.

Aspects of the SrO-CuO-TiO₂ Ternary System Related to the Deposition of SrTiO₃ and Copper-Doped SrTiO₃ Thin-Film Buffer Layers

Energy Technology Data Exchange (ETDEWEB)

Ayala, Alicia [Univ. of New Mexico, Albuquerque, NM (United States)

2004-12-20

YBa₂Cu₃O_27-δ (YBCO) coated conductors are promising materials for large-scale superconductivity applications. One version of a YBCO coated conductor is based on ion beam assisted deposition (IBAD) of magnesium oxide (MgO) onto polycrystalline metal substrates. SrTiO₃ (STO) is often deposited by physical vapor deposition (PVD) methods as a buffer layer between the YBCO and IBAD MgO due to its chemical stability and lattice mismatch of only ~1.5% with YBCO. In this work, some aspects of the stability of STO with respect to copper (Cu) and chemical solution deposition of STO on IBAD MgO templates were examined. Solubility limits of Cu in STO were established by processing Cu-doped STO powders by conventional bulk preparation techniques. The maximum solubility of Cu in STO was ~1% as determined by transmission electron microscopy (TEM) and Rietveld refinements of x-ray diffraction (XRD) data. XRD analysis, performed in collaboration with NIST, on powder compositions on the STO/SrCuO₂ tie line did not identify any ternary phases. SrCu_0.10T_0.90O_y buffer layers were prepared by pulsed laser deposition (PLD) and CSD on IBAD MgO flexible metallic textured tapes. TEM analysis of a ~100 nm thick SrCu_0.10Ti_0.90O_y buffer layer deposited by PLD showed a smooth Cu-doped STO/MgO interface. A ~600 nm thick YBCO film, deposited onto the SrCu_0.10Ti_0.90O_y buffer by PLD, exhibited a T_c of 87 K and critical current density (J_c) of ~1 MA/cm². STO and Cu-doped STO thin films by CSD were ~30 nm thick. The in plane alignment (FWHM) after deposition of the STO improved by ~1° while it degraded by ~2° with the SrCu_0.05TiO_y buffer. YBCO was deposited by PLD on the STO and SrCu_0.05TiO_y buffers. The in plane alignment (FWHM) of the YBCO with the STO buffer layer

Enhancement of photocatalytic degradation of polyethylene plastic with CuPc modified TiO2 photocatalyst under solar light irradiation

International Nuclear Information System (INIS)

Zhao Xu; Li Zongwei; Chen Yi; Shi Liyi; Zhu Yongfa

2008-01-01

Solid-phase photocatalytic degradation of polyethylene (PE) plastic, one of the most common commercial plastic, over copper phthalocyanine (CuPc) modified TiO 2 (TiO 2 /CuPc) photocatalyst was investigated in the ambient air under solar light irradiation. Higher PE weight loss rate, greater texture change; more amount of generated CO 2 , which is the main product of the photocatalytic degradation of the composite PEC plastic can be achieved in the system of PE-(TiO 2 /CuPc) in comparison with PE-TiO 2 system. The CuPc promoted charge separation of TiO 2 and enhanced the photocatalytic degradation of PE based on the analysis of surface photovoltage spectroscopy (SPS). During the photodegradation of PE plastic, the reactive oxygen species generated on TiO 2 or TiO 2 /CuPc particle surfaces play important roles. The present study demonstrates that the combination of polymer plastic with TiO 2 /CuPc composite photocatalyst in the form of thin film is a practical and useful way to photodegrade plastic contaminants under solar light irradiation

Incorporating TiO2 nanotubes with a peptide of D-amino K122-4 (D) for enhanced mechanical and photocatalytic properties

Science.gov (United States)

Guo, L. Q.; Hu, Y. W.; Yu, B.; Davis, E.; Irvin, R.; Yan, X. G.; Li, D. Y.

2016-02-01

Titanium dioxide (TiO2) nanotubes are promising for a wide variety of potential applications in energy, biomedical and environmental sectors. However, their low mechanical strength and wide band gap limit their widespread technological use. This article reports our recent efforts to increase the mechanical strength of TiO2 nanotubes with lowered band gap by immobilizing a peptide of D-amino K122-4 (D) onto the nanotubes. Topographies and chemical compositions of the peptide-coated and uncoated TiO2 nanotubular arrays were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy (XPS). Properties of the peptide-coated and uncoated TiO2 nanotubular arrays, including hardness, elastic modulus, electron work function and photocurrent, were evaluated using micromechanical probe, Kelvin Probe and electrochemical system. Effect of the peptide on surface conductivity was also investigated through current mapping and I-V curve analysis with conductive atomic force microscopy. It is demonstrated that the peptide coating simultaneously enhances the mechanical strength, photocatalytic and electrical properties of TiO2 nanotubes.

Synthesis and magnetotransport studies of CrO2 films grown on TiO2 nanotube arrays by chemical vapor deposition

Science.gov (United States)

Wang, Xiaoling; Zhang, Caiping; Wang, Lu; Lin, Tao; Wen, Gehui

2018-04-01

The CrO2 films have been prepared on the TiO2 nanotube array template via atmospheric pressure chemical vapor deposition method. And the growth procedure was studied. In the beginning of the deposition process, the CrO2 grows on the cross section of the TiO2 nanotubes wall, forms a nanonet-like layer. And the grain size of CrO2 is very small. With the increase of the deposition time, the grain size of CrO2 also increases, and the nanonet-like layer changes into porous film. With the further increase of the deposition time, all the nanotubes are covered by CrO2 grains and the surface structure becomes polycrystalline film. The average grain size on the surface of the CrO2 films deposited for 1 h, 2 h and 5 h is about 190 nm, 300 nm and 470 nm. The X-ray diffraction pattern reveals that the rutile CrO2 film has been synthesized on the TiO2 nanotube array template. The CrO2 films show large magnetoresistance (MR) at low temperature, which should originate from spin-dependent tunneling through grain boundaries between CrO2 grains. And the tunneling mechanism of the CrO2 films can be well described by the fluctuation-induced tunneling (FIT) model. The CrO2 film deposited for 2 h shows insulator behavior from 5 k to 300 K, but the CrO2 film deposited for 5 h shows insulator-metal transition around 140 K. The reason is briefly discussed.

Tantalum coating on TiO2 nanotubes induces superior rate of matrix mineralization and osteofunctionality in human osteoblasts

International Nuclear Information System (INIS)

Frandsen, Christine J.; Brammer, Karla S.; Noh, Kunbae; Johnston, Gary; Jin, Sungho

2014-01-01

Nanostructured surface geometries have been the focus of a multitude of recent biomaterial research, and exciting findings have been published. However, only a few publications have directly compared nanostructures of various surface chemistries. The work herein directly compares the response of human osteoblast cells to surfaces of identical nanotube geometries with two well-known orthopedic biomaterials: titanium oxide (TiO 2 ) and tantalum (Ta). The results reveal that the Ta surface chemistry on the nanotube architecture enhances alkaline phosphatase activity, and promotes a ∼ 30% faster rate of matrix mineralization and bone-nodule formation when compared to results on bare TiO 2 nanotubes. This study implies that unique combinations of surface chemistry and nanostructure may influence cell behavior due to distinctive physico-chemical properties. These findings are of paramount importance to the orthopedics field for understanding cell behavior in response to subtle alterations in nanostructure and surface chemistry, and will enable further insight into the complex manipulation of biomaterial surfaces. With increased focus in the field of orthopedic materials research on nanostructured surfaces, this study emphasizes the need for careful and systematic review of variations in surface chemistry in concurrence with nanotopographical changes. - Highlights: • A TiO 2 nanotube surface structure was coated with tantalum. • Osteoblast cell response was compared between the tantalum coated and as-formed TiO 2 nanotube surface. • We observed superior rates of bone matrix mineralization and osteoblast maturation on the tantalum coated nanotube surface

1 composite mixture of TiO2 nanoparticles and nanotubes in dye

Indian Academy of Sciences (India)

Administrator

Abstract. TiO2-based nanotubes (NTs), nanoparticles (NPs) and composite structural film (50% NP + 50% ... of faster electron injection ratio compared with other .... exist in this system. .... the open circuit voltage, Im the maximum current and.

Electrochemically synthesized visible light absorbing vertically aligned N-doped TiO2 nanotube array films

International Nuclear Information System (INIS)

Antony, Rajini P.; Mathews, Tom; Ajikumar, P.K.; Krishna, D. Nandagopala; Dash, S.; Tyagi, A.K.

2012-01-01

Graphical abstract: Display Omitted Highlights: ► Single step electrochemical synthesis of N-doped TiO 2 nanotube array films. ► Effective substitutional N-doping achieved. ► Different N-concentrations were achieved by varying the N-precursor concentration in the electrolyte. ► Visible light absorption observed at high N-doping. -- Abstract: Visible light absorbing vertically aligned N-doped anatase nanotube array thin films were synthesized by anodizing Ti foils in ethylene glycol + NH 4 F + water mixture containing urea as nitrogen source. Different nitrogen concentrations were achieved by varying the urea content in the electrolyte. The structure, morphology, composition and optical band gap of the nanotube arrays were determined by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy, respectively. The substitution of O 2− ions by N 3− ions in the anion sublattice as well as the formulae of the doped samples was confirmed from the results of XPS. The optical band gap of the nanotube arrays was found to decrease with N-concentration. The sample with the highest concentration corresponding to the formula TiO 1.83 N 0.14 showed two regions in the Tauc's plot indicating the presence of interband states.

Facile synthesis, enhanced field emission and photocatalytic activities of Cu2O–TiO2–ZnO ternary hetero-nanostructures

International Nuclear Information System (INIS)

Wang Yang; Yu Ke; Yin Haihong; Song Changqin; Zhang Zhengli; Li Shouchuan; Zhang Qingfeng; Zhao Bin; Zhang Yingfang; Zhu Ziqiang; Shi Hui

2013-01-01

Cu 2 O–TiO 2 –ZnO ternary nano-heteroarchitectures were designed and successfully fabricated using titanium (IV) oxideacetylacetonate (TiO(acac) 2 ) as a precursor and polyethyleneimine (PEI) as a binding agent. Field emission and photocatalytic activities of pure Cu 2 O nanopines, Cu 2 O–TiO 2 core–shell nanopines and Cu 2 O–TiO 2 –ZnO ternary composites were investigated and compared. The results revealed that the as-prepared nano-heterojunctions and nanoparticles at the surface remarkably enhanced the field emission and photocatalytic activities of pure Cu 2 O nanopines. The as-prepared nano-heterojunctions induced interfacial states and energy band differentials, which caused electron transition and the inhibition of photo-induced electron–hole pair recombination. The nanoparticles at the surface formed thousands of surface nano-protrusions and active sites for photocatalytic chemical reactions. (paper)

Optimizing TiO2 nanotube top geometry for use in dye-sensitized solar cells.

Science.gov (United States)

Mir, Nooshin; Lee, Kiyoung; Paramasivam, Indhumati; Schmuki, Patrik

2012-09-17

Recombination dynamics: For TiO(2) nanotube-based dye-sensitized solar cells, the efficiency can be drastically enhanced by a synergetic effect that occurs when using nanowire-ended nanotubes in combination with an adequate nanoparticle decoration (see figure). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Controlled Synthesis of CuS/TiO2 Heterostructured Nanocomposites for Enhanced Photocatalytic Hydrogen Generation through Water Splitting.

Science.gov (United States)

Chandra, Moumita; Bhunia, Kousik; Pradhan, Debabrata

2018-04-16

Photocatalytic hydrogen (H 2 ) generation through water splitting has attracted substantial attention as a clean and renewable energy generation process that has enormous potential in converting solar-to-chemical energy using suitable photocatalysts. The major bottleneck in the development of semiconductor-based photocatalysts lies in poor light absorption and fast recombination of photogenerated electron-hole pairs. Herein we report the synthesis of CuS/TiO 2 heterostructured nanocomposites with varied TiO 2 contents via simple hydrothermal and solution-based process. The morphology, crystal structure, composition, and optical properties of the as-synthesized CuS/TiO 2 hybrids are evaluated in detail. Controlling the CuS/TiO 2 ratio to an optimum value leads to the highest photocatalytic H 2 production rate of 1262 μmol h -1 g -1 , which is 9.7 and 9.3 times higher than that of pristine TiO 2 nanospindles and CuS nanoflakes under irradiation, respectively. The enhancement in the H 2 evolution rate is attributed to increased light absorption and efficient charge separation with an optimum CuS coverage on TiO 2 . The photoluminescence and photoelectrochemical measurements further confirm the efficient separation of charge carriers in the CuS/TiO 2 hybrid. The mechanism and synergistic role of CuS and TiO 2 semiconductors for enhanced photoactivity is further delineated.

Synthesis of high efficient Cu/TiO2 photocatalysts by grinding and their size-dependent photocatalytic hydrogen production

Science.gov (United States)

Ni, Dawei; Shen, Haiyan; Li, Huiqiao; Ma, Ying; Zhai, Tianyou

2017-07-01

Recently, copper species have been extensively investigated to replace Pt as efficient co-catalysts for the evolution of H2 due to their low cost and relatively high activity. Cu nanoparticles less than 5 nm are successfully decorated on TiO2 surface in this work by an easy and mild milling process. These Cu nanoparticles are highly dispersed on TiO2 when the loading amount of Cu is no more than 10 wt%. The sizes of Cu nanoparticles can be controlled by changing the milling environment and decrease in the order of Cu-ethanol > Cu-water > Cu nanoparticles obtained through drying milling. The highest and stable hydrogen generation can be realized on Cu/TiO2 with 2.0 wt% Cu and sizes of Cu nanoparticles ranging from 2 to 4 nm, in which high and stable photocurrent confirms promoted photogenerated charge separation. Smaller Cu clusters are demonstrated to be detrimental to hydrogen evolution at same Cu content. High loading of Cu nanoparticles of 2-4 nm will benefit photogenerated electron-hole recombination and thus decrease the activity of Cu/TiO2. The results here demonstrate the key roles of Cu cluster size in addition to Cu coverage on photocatalytic activity of Cu/TiO2 composite photocatalysts.