Science.gov

Sample records for incorporating tio2 nanotube

  1. Synthesis of silver quantum dots decorated TiO2 nanotubes and their incorporation in organic hybrid solar cells

    NASA Astrophysics Data System (ADS)

    Tan, Furui; Qu, Shengchun; Zhang, Xingwang; Liu, Kong; Wang, Zhanguo

    2013-08-01

    Uniform silver quantum dots decorated TiO2 nanotubes (Ag-TiO2 NTs) were synthesized via a simple reduction reaction in ethanol solvent. The size distribution of composite NTs arranges from 3 to 5 nm for Ag quantum dots and about 10 nm for TiO2 NTs in diameter. The composite Ag-TiO2 nanoparticles were incorporated in organic hybrid solar cells through doping into the active layer. Both the optical and electrical properties of the solar cells were improved. The photocurrent and fill factor of the devices were obviously increased after the Ag-TiO2 NTs were introduced, accompanied with a greatly reduced series resistance as well as enlarged shunt resistance. Suppressed recombination due to efficient charge transfer from plasmonic Ag quantum dots to the attached TiO2 NTs made contribution to the charge collection and transportation so that the fill factor was increased. Meanwhile, the enhanced light absorption resulted from effective incident light scattering by the Ag-TiO2 NTs composite played a role in increasing photocurrent. As a result, solar cells with Ag-TiO2 NTs generated an enhanced conversion efficiency up to 20 and 50 % compared to that adopting TiO2 NTs and that without doping, respectively.

  2. Optimizing stem cell functions and antibacterial properties of TiO2 nanotubes incorporated with ZnO nanoparticles: experiments and modeling.

    PubMed

    Liu, Wenwen; Su, Penglei; Gonzales, Arthur; Chen, Su; Wang, Na; Wang, Jinshu; Li, Hongyi; Zhang, Zhenting; Webster, Thomas J

    2015-01-01

    To optimize mesenchymal stem cell differentiation and antibacterial properties of titanium (Ti), nano-sized zinc oxide (ZnO) particles with tunable concentrations were incorporated into TiO2 nanotubes (TNTs) using a facile hydrothermal strategy. It is revealed here for the first time that the TNTs incorporated with ZnO nanoparticles exhibited better biocompatibility compared with pure Ti samples (controls) and that the amount of ZnO (tailored by the concentration of Zn(NO3)2 in the precursor) introduced into TNTs played a crucial role on their osteogenic properties. Not only was the alkaline phosphatase activity improved to about 13.8 U/g protein, but the osterix, collagen-I, and osteocalcin gene expressions was improved from mesenchymal stem cells compared to controls. To further explore the mechanism of TNTs decorated with ZnO on cell functions, a response surface mathematical model was used to optimize the concentration of ZnO incorporation into the Ti nanotubes for stem cell differentiation and antibacterial properties for the first time. Both experimental and modeling results confirmed (R (2) values of 0.8873-0.9138 and 0.9596-0.9941, respectively) that Ti incorporated with appropriate concentrations (with an initial concentration of Zn(NO3)2 at 0.015 M) of ZnO can provide exceptional osteogenic properties for stem cell differentiation in bone cells with strong antibacterial effects, properties important for improving dental and orthopedic implant efficacy.

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

    PubMed

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

    2016-02-26

    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.

  4. Both enhanced biocompatibility and antibacterial activity in Ag-decorated TiO2 nanotubes.

    PubMed

    Lan, Ming-Ying; Liu, Chia-Pei; Huang, Her-Hsiung; Lee, Sheng-Wei

    2013-01-01

    In this study, Ag is electron-beam evaporated to modify the topography of anodic TiO2 nanotubes of different diameters to obtain an implant with enhanced antibacterial activity and biocompatibility. We found that highly hydrophilic as-grown TiO2 nanotubes became poorly hydrophilic with Ag incorporation; however they could effectively recover their wettability to some extent under ultraviolet light irradiation. The results obtained from antibacterial tests suggested that the Ag-decorated TiO2 nanotubes could greatly inhibit the growth of Staphylococcus aureus. In vitro biocompatibility evaluation indicated that fibroblast cells exhibited an obvious diameter-dependent behavior on both as-grown and Ag-decorated TiO2 nanotubes. Most importantly, of all samples, the smallest diameter (25-nm-diameter) Ag-decorated nanotubes exhibited the most obvious biological activity in promoting adhesion and proliferation of human fibroblasts, and this activity could be attributed to the highly irregular topography on a nanometric scale of the Ag-decorated nanotube surface. These experimental results demonstrate that by properly controlling the structural parameters of Ag-decorated TiO2 nanotubes, an implant surface can be produced that enhances biocompatibility and simultaneously boosts antibacterial activity.

  5. Dye-sensitized TiO2 nanotube solar cells: rational structural and surface engineering on TiO2 nanotubes.

    PubMed

    Wang, Jun; Lin, Zhiqun

    2012-12-01

    Owing to well-defined structural parameters and enhanced electronic properties, highly ordered TiO(2) nanotube arrays have been employed to substitute TiO(2) nanoparticles for use in dye-sensitized solar cells. To further improve the performance of dye-sensitized TiO(2) nanotube solar cells, efforts have been directed toward the optimization of TiO(2) photoanodes, dyes, electrolytes, and counter electrodes. Herein, we highlight recent progress in rational structural and surface engineering on anodic TiO(2) nanotube arrays and their effects on improving the power conversion efficiency of dye-sensitized TiO(2) nanotube solar cells.

  6. Hydroxyapatite growth on anodic TiO2 nanotubes.

    PubMed

    Tsuchiya, Hiroaki; Macak, Jan M; Müller, Lenka; Kunze, Julia; Müller, Frank; Greil, Peter; Virtanen, Sannakaisa; Schmuki, Patrik

    2006-06-01

    In the present work, we study the growth of hydroxyapatite formation on different TiO(2) nanotube layers. The nanotube layers were fabricated by electrochemical anodization of titanium in fluoride-containing electrolytes. To study various nanotube lengths, layers with an individual tube diameter of 100 nm were grown to a thickness of approximately 2 mum or 500 nm. The ability to form apatite on the nanotube layers was examined by immersion tests combined with SEM, XRD and FT-IR investigations. For reference, experiments were also carried out on compact anodic TiO(2) layers. The results clearly show that the presence of the nanotubes on a titanium surface enhances the apatite formation and that the 2-mum thick nanotube layer triggers deposition faster than the thinner layers. Tubes annealed to anatase, or a mixture of anatase and rutile are clearly more efficient in promoting apatite formation than the tubes in their "as-formed" amorphous state.

  7. Preparation of TiO2 nanotubes/mesoporous calcium silicate composites with controllable drug release.

    PubMed

    Xie, Chunling; Li, Ping; Liu, Yan; Luo, Fei; Xiao, Xiufeng

    2016-10-01

    Nanotube structures such as TiO2 nanotube (TNT) arrays produced by self-ordering electrochemical anodization have been extensively explored for drug delivery applications. In this study, we presented a new implantable drug delivery system that combined mesoporous calcium silicate coating with nanotube structures to achieve a controllable drug release of water soluble and antiphlogistic drug loxoprofen sodium. The results showed that the TiO2 nanotubes/mesoporous calcium silicate composites were successfully fabricated by a simple template method and the deposition of mesoporous calcium silicate increased with the soaking time. Moreover, the rate of deposition of biological mesoporous calcium silicate on amorphous TNTs was better than that on anatase TNTs. Further, zinc-incorporated mesoporous calcium silicate coating, produced by adding a certain concentration of zinc nitrate into the soaking system, displayed improved chemical stability. A significant improvement in the drug release characteristics with reduced burst release and sustained release was demonstrated.

  8. Study of TiO2 nanotubes as an implant application

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    Vertically aligned TiO2 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 TiO2 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 TiO2 nanotubes is reported. Field emission scanning electron microscopy (FESEM) analysis proved interaction of BMSC on TiO2 nanotubes structure was better than flat titanium (Ti) surface. Also, significant cell adhesion on TiO2 nanotubes surface during in vitro study revealed that BMSC prone to attach on TiO2 nanotubes. From the result, it can be conclude that TiO2 nanotubes are biocompatible to biological environment and become a new generation for advanced implant materials.

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

    PubMed

    Chan, Donald K L; Cheung, Po Ling; Yu, Jimmy C

    2014-01-01

    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.

  10. AC conductivity studies of Fe doped TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Vijayan, P. P.; Thomas, M.; George, K. C.

    2015-02-01

    Fe-doped TiO2 nanotubes are prepared by the combination of sol-gel process with hydrothermal treatment. The morphology and crystalline structure of TiO2 nanotubes are characterized by transmission electron microscopy (TEM), X-ray diffraction respectively (XRD). Fe doping induces a structural transformation from anatase to rutile. The temperature dependence of the ac electrical conductivity is investigated in the temperature range 303-413 K. Positive temperature coefficient of resistance is observed in the Fe doped TiO2 nanotubes. PL spectrum shows the presence of oxygen vacancies and self trapped excitons in Fe doped TiO2 nanotubes and undoped samples.

  11. TiO2 nanotubes and mesoporous silica as containers in self-healing epoxy coatings

    NASA Astrophysics Data System (ADS)

    Vijayan P., Poornima; Al-Maadeed, Mariam Ali S. A.

    2016-12-01

    The potential of inorganic nanomaterials as reservoirs for healing agents is presented here. Mesoporous silica (SBA-15) and TiO2 nanotubes (TNTs) were synthesized. Both epoxy-encapsulated TiO2 nanotubes and amine-immobilized mesoporous silica were incorporated into epoxy and subsequently coated on a carbon steel substrate. The encapsulated TiO2 nanotubes was quantitatively estimated using a ‘dead pore ratio’ calculation. The morphology of the composite coating was studied in detail using transmission electron microscopic (TEM) analysis. The self-healing ability of the coating was monitored using electrochemical impedance spectroscopy (EIS); the coating recovered 57% of its anticorrosive property in 5 days. The self-healing of the scratch on the coating was monitored using Scanning Electron Microscopy (SEM). The results confirmed that the epoxy pre-polymer was slowly released into the crack. The released epoxy pre-polymer came into contact with the amine immobilized in mesoporous silica and cross-linked to heal the scratch.

  12. TiO2 nanotubes and mesoporous silica as containers in self-healing epoxy coatings

    PubMed Central

    Vijayan P., Poornima; Al-Maadeed, Mariam Ali S. A.

    2016-01-01

    The potential of inorganic nanomaterials as reservoirs for healing agents is presented here. Mesoporous silica (SBA-15) and TiO2 nanotubes (TNTs) were synthesized. Both epoxy-encapsulated TiO2 nanotubes and amine-immobilized mesoporous silica were incorporated into epoxy and subsequently coated on a carbon steel substrate. The encapsulated TiO2 nanotubes was quantitatively estimated using a ‘dead pore ratio’ calculation. The morphology of the composite coating was studied in detail using transmission electron microscopic (TEM) analysis. The self-healing ability of the coating was monitored using electrochemical impedance spectroscopy (EIS); the coating recovered 57% of its anticorrosive property in 5 days. The self-healing of the scratch on the coating was monitored using Scanning Electron Microscopy (SEM). The results confirmed that the epoxy pre-polymer was slowly released into the crack. The released epoxy pre-polymer came into contact with the amine immobilized in mesoporous silica and cross-linked to heal the scratch. PMID:27941829

  13. Tunable TiO2 Nanotube Arrays for Flexible Bio-Sensitized Solar Cells

    DTIC Science & Technology

    2012-08-01

    Tunable TiO2 Nanotube Arrays for Flexible Bio-Sensitized Solar Cells by Joshua J. Martin, Mark H. Griep, Anit Giri, Samuel G. Hirsch... Tio2 Nanotube Arrays for Flexible Bio-Sensitized Solar Cells 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...pathway vs. TiO2 nanoparticles in dye-sensitized solar cell (DSSC) designs. TiNT arrays prepared by electrochemical anodization of Ti foils and

  14. Antibacterial activity of TiO2 nanotubes: Influence of crystal phase, morphology and Ag deposition

    NASA Astrophysics Data System (ADS)

    Li, Huirong; Cui, Qiang; Feng, Bo; Wang, Jianxin; Lu, Xiong; Weng, Jie

    2013-11-01

    TiO2 nanotubes on Ti substrate were fabricated by electrochemical anodization. Ag nanoparticles were deposited on the TiO2 nanotubes by a silver mirror reaction. Antibacterial activity of the nanotubes with different structural features was evaluated by a culture test with Escherichia coli bacteria. The anatase nanotubes showed the highest antibacterial activity among three crystal phases including anatase, rutile and amorphous titania. The diameters of the nanotubes affected the antibacterial activity. The two nanotubes with 200 nm and 50 nm diameters had higher antibacterial rate than those with other diameters. The antibacterial activity of the nanotubes was independent on their lengths. Ag-deposited nanotubes exhibited excellent antibacterial activity and its antibacterial rate was up to approximately 100%. TiO2 nanotubes and Ag-deposited nanotubes on titanium should be potential for antibacterial applications in clinics and industry, especially regarding with their reusability.

  15. Fabrication and photocatalytic activity of TiO2 derived nanotubes with Ag ions doping.

    PubMed

    Liu, Fang; Lai, Shuting; Huang, Peilin; Liu, Yingju; Xu, Yuehua; Fang, Yueping; Zhou, Wuyi

    2012-11-01

    Ag/TiO2 nanotubes with uniform distribution were successfully prepared by a hydrothermal-dipping method. The synthesized samples were characterized by XRD, TEM and FTIR, respectively. The results exhibited that the morphological structure of the TiO2 nanotubes was improved by the doping of Ag ions. The photocatalytic degradation experiment indicated that the photocatalytic activity of the Ag/TiO2 nanotubes indicated better photocatalytic activity than pure TiO2 nanotubes since silver was able to help the electron-hole separation by attracting photoelectrons. The optimal mol ration of TiO2 and AgNO3 was 25:1.

  16. Graphene oxide modified TiO2 nanotube arrays: enhanced visible light photoelectrochemical properties

    NASA Astrophysics Data System (ADS)

    Song, Peng; Zhang, Xiaoyan; Sun, Mingxuan; Cui, Xiaoli; Lin, Yuehe

    2012-02-01

    Novel nanocomposite films, based on graphene oxide (GO) and TiO2 nanotube arrays, were synthesized by assembling GO on the surface of self-organized TiO2 nanotube arrays through a simple impregnation method. The composite films were characterized with field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy and UV-vis diffuse reflectance spectroscopy. The photoelectrochemical properties of the composite nanotube arrays were investigated under visible light illumination. Remarkably enhanced visible light photoelectrochemical response was observed for the GO decorated TiO2 nanotube composite electrode compared with pristine TiO2 nanotube arrays. The sensitizing effect of GO on the photoelectrochemical response of the TiO2 nanotube arrays was demonstrated and about 15 times enhanced maximum photoconversion efficiency was obtained with the presence of GO. An enhanced photocatalytic activity of the TiO2 nanotube arrays towards the degradation of methyl blue was also demonstrated after modification with GO. The results presented here demonstrate GO to be efficient for the improved utilization of visible light for TiO2 nanotube arrays.

  17. Graphene oxide modified TiO2 nanotube arrays: enhanced visible light photoelectrochemical properties.

    PubMed

    Song, Peng; Zhang, Xiaoyan; Sun, Mingxuan; Cui, Xiaoli; Lin, Yuehe

    2012-03-07

    Novel nanocomposite films, based on graphene oxide (GO) and TiO(2) nanotube arrays, were synthesized by assembling GO on the surface of self-organized TiO(2) nanotube arrays through a simple impregnation method. The composite films were characterized with field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy and UV-vis diffuse reflectance spectroscopy. The photoelectrochemical properties of the composite nanotube arrays were investigated under visible light illumination. Remarkably enhanced visible light photoelectrochemical response was observed for the GO decorated TiO(2) nanotube composite electrode compared with pristine TiO(2) nanotube arrays. The sensitizing effect of GO on the photoelectrochemical response of the TiO(2) nanotube arrays was demonstrated and about 15 times enhanced maximum photoconversion efficiency was obtained with the presence of GO. An enhanced photocatalytic activity of the TiO(2) nanotube arrays towards the degradation of methyl blue was also demonstrated after modification with GO. The results presented here demonstrate GO to be efficient for the improved utilization of visible light for TiO(2) nanotube arrays.

  18. A TiO2 nanotube network electron transport layer for high efficiency perovskite solar cells.

    PubMed

    Gao, Xianfeng; Li, Jianyang; Gollon, Sam; Qiu, Ming; Guan, Dongsheng; Guo, Xiaoru; Chen, Junhong; Yuan, Chris

    2017-02-15

    The electron transport layer (ETL) plays a critical role in high efficiency perovskite solar cells. In this study, an anodic TiO2 nanotube film was transformed into a TiO2 nanotube network film, which maintained its advantage as an efficient ETL for perovskite solar cells. Compared with the mesoporous TiO2 nanoparticle ETL, the TiO2 nanotube network ETL can increase the efficiency of perovskite solar cells by 26.6%, which is attributed to its superior charge collection property and light trapping ability. The results confirm the importance of optimizing the electron collecting layer and suggest another way to design and fabricate novel perovskite solid state solar cells, potentially by using a TiO2 nanotube network film as an alternative high efficiency electrode.

  19. Cr2O3 nanoparticles modified TiO2 nanotubes for enhancing visible photoelectrochemical performance.

    PubMed

    Zhang, Fen; Jin, Tao; Zeng, Rongchang; Cui, Hongzhi; Song, Liang

    2014-09-01

    TiO2 nanotube arrays modified by nanoparticles Cr2O3 with high sensibility in the visible spectrum were prepared by annealing the anodic TiO2 nanotube arrays pre-loaded with Cr(NO3)3 solution which was uniformly clung to the TiO2 nanotube arrays. The influence of the dipping time on the microstructure of the Cr2O3/TiO2-nanotubes was investigated. The microstructure and the elemental analysis were characterized by scanning electron microscope (SEM) and Energy dispersive X-ray (EDX). The photoelectrochemical performances of the as-prepared composite nanotubes were determined by measuring the photogenerated current and voltage under illumination of ultraviolet-visible (UV-vis)/visible light. The TiO2 nanotube arrays modified by Cr2O3 showed higher photocurrent values than those of unmodified TiO2 nanotube arrays. The enhanced photoelectrochemical behaviors can be attributed to the modified Cr2O3 which increases the probability of charge-carrier separation and extends the range of the TiO2 photoresponse from UV to visible region due to the low band gap of 2.3 eV of Cr2O3.

  20. Fast diffusion of silver in TiO2 nanotube arrays.

    PubMed

    Zhang, Wanggang; Liu, Yiming; Zhou, Diaoyu; Wang, Hui; Liang, Wei; Yang, Fuqian

    2016-01-01

    Using magnetron sputtering and heat treatment, Ag@TiO2 nanotubes are prepared. The effects of heat-treatment temperature and heating time on the evolution of Ag nanofilms on the surface of TiO2 nanotubes and microstructure of Ag nanofilms are investigated by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. Ag atoms migrate mainly on the outmost surface of the TiO2 nanotubes, and fast diffusion of Ag atoms is observed. The diffusivity for the diffusion of Ag atoms on the outmost surface of the TiO2 nanotubes at 400 °C is 6.87 × 10(-18) m(2)/s, which is three orders of magnitude larger than the diffusivities for the diffusion of Ag through amorphous TiO2 films. The activation energy for the diffusion of Ag atoms on the outmost surface of the TiO2 nanotubes in the temperature range of 300 to 500 °C is 157 kJ/mol, which is less than that for the lattice diffusion of Ag and larger than that for the grain boundary diffusion. The diffusion of Ag atoms leads to the formation of Ag nanocrystals on the outmost surface of TiO2 nanotubes. Probably there are hardly any Ag nanocrystals formed inside the TiO2 nanotubes through the migration of Ag.

  1. Fast diffusion of silver in TiO2 nanotube arrays

    PubMed Central

    Zhang, Wanggang; Liu, Yiming; Zhou, Diaoyu; Wang, Hui

    2016-01-01

    Summary Using magnetron sputtering and heat treatment, Ag@TiO2 nanotubes are prepared. The effects of heat-treatment temperature and heating time on the evolution of Ag nanofilms on the surface of TiO2 nanotubes and microstructure of Ag nanofilms are investigated by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. Ag atoms migrate mainly on the outmost surface of the TiO2 nanotubes, and fast diffusion of Ag atoms is observed. The diffusivity for the diffusion of Ag atoms on the outmost surface of the TiO2 nanotubes at 400 °C is 6.87 × 10−18 m2/s, which is three orders of magnitude larger than the diffusivities for the diffusion of Ag through amorphous TiO2 films. The activation energy for the diffusion of Ag atoms on the outmost surface of the TiO2 nanotubes in the temperature range of 300 to 500 °C is 157 kJ/mol, which is less than that for the lattice diffusion of Ag and larger than that for the grain boundary diffusion. The diffusion of Ag atoms leads to the formation of Ag nanocrystals on the outmost surface of TiO2 nanotubes. Probably there are hardly any Ag nanocrystals formed inside the TiO2 nanotubes through the migration of Ag. PMID:27547630

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

    PubMed

    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.

  3. Activity of vancomycin release from bioinspired coatings of hydroxyapatite or TiO2 nanotubes.

    PubMed

    Ionita, Daniela; Bajenaru-Georgescu, Daniela; Totea, Georgeta; Mazare, Anca; Schmuki, Patrik; Demetrescu, Ioana

    2017-01-30

    Herein we investigate the efficiency of various biomimetic coatings for localized drug delivery, using vancomycin as key therapeutic drug, which is a widely used antibiotic for the treatment of strong infections caused by positive Gram bacteria. We evaluate classical hydroxyapatite and biomimetic hydroxyapatite-collagen coatings obtained by electrochemical deposition as well as TiO2 nanotubes arrays obtained by electrochemical anodization. Surface morphology, compositional and structural data confirm the incorporation of vancomycin into the layers and drug release profiles for vancomycin evaluate their release ability. Namely, hydroxyapatite coatings lead to a ≈92% vancomycin release after 30h and hydroxyapatite-collagen to 85%, while the TiO2 nanotubes layers lead to 78% release. The antibacterial effect of such drug loaded coatings is evaluated against S. aureus (Gram-positive bacteria). Our study shows that the vancomycin incorporated hydroxyapatite coatings lead to a faster release, while the nanotubular coatings may lead to longer time release and additionally both types of coatings ensure a good antibacterial inhibition.

  4. Inverted polymer solar cells with employing of electrochemical-anodizing synthesized TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Mehdi, Ahmadi; Sajjad Rashidi, Dafeh; Hamed, Fatehy

    2016-04-01

    An inverted structure of polymer solar cells based on Poly(3-hexylthiophene)(P3HT):[6-6] Phenyl-(6) butyric acid methyl ester (PCBM) with using thin films of TiO2 nanotubes and nanoparticles as an efficient cathode buffer layer is developed. A total of three cells employing TiO2 thin films with different thickness values are fabricated. Two cells use layers of TiO2 nanotubes prepared via self-organized electrochemical-anodizing leading to thickness values of 203 and 423.7 nm, while the other cell uses only a simple sol-gel synthesized TiO2 thin film of nanoparticles with a thickness of 100 nm as electron transport layer. Experimental results demonstrate that TiO2 nanotubes with these thickness values are inefficient as the power conversion efficiency of the cell using 100-nm TiO2 thin film is 1.55%, which is more than the best power conversion efficiency of other cells. This can be a result of the weakness of the electrochemical anodizing method to grow nanotubes with lower thickness values. In fact as the TiO2 nanotubes grow in length the series resistance (R s) between the active polymer layer and electron transport layer increases, meanwhile the fill factor of cells falls dramatically which finally downgrades the power conversion efficiency of the cells as the fill factor falls.

  5. TiO2-coated carbon nanotubes: A redshift enhanced photocatalysis at visible light

    NASA Astrophysics Data System (ADS)

    Lu, Sheng-Yi; Tang, Chiung-Wen; Lin, Yu-Hsien; Kuo, Hsin-Fu; Lai, Yao-Cheng; Tsai, Meng-Yen; Ouyang, Hao; Hsu, Wen-Kuang

    2010-06-01

    Annealing of carbon nanotubes coated with thin and uniform TiO2 results in carbon diffusion into oxygen lattices and doping induced redshift is evident by an efficient photocatalysis at visible light. The underlying mechanism is discussed.

  6. Controlled fabrication of porous double-walled TiO2 nanotubes via ultraviolet-assisted anodization

    NASA Astrophysics Data System (ADS)

    Ali, Ghafar; Kim, Hyun Jin; Kim, Jae Joon; Cho, Sung Oh

    2014-03-01

    Double-walled TiO2 nanotubes with porous wall morphologies are fabricated by anodization under ultraviolet (UV) irradiation. TiO2 formed by anodization of Ti is activated to generate electrons and holes by UV and the anodization process is influenced by the photo-generated charges. As a consequence, morphologies of the fabricated TiO2 nanotubes can be adjusted by controlling the UV illumination. Double-walled TiO2 nanotubes or single-walled nanotubes can be selectively formed by switching on/off the UV illumination. The thickness of the inner and outer walls of the double-walled nanotubes can be tailored by changing the UV power. Due to their larger surface areas compared to single-walled nanotubes, the porous double-walled nanotubes exhibit an enhanced photo-degradation rate for methylene blue (MB). The mechanism of the porous double-walled TiO2 nanotubes is proposed based on the photoactive semiconducting property of the as-growing TiO2 nanotubes under UV.Double-walled TiO2 nanotubes with porous wall morphologies are fabricated by anodization under ultraviolet (UV) irradiation. TiO2 formed by anodization of Ti is activated to generate electrons and holes by UV and the anodization process is influenced by the photo-generated charges. As a consequence, morphologies of the fabricated TiO2 nanotubes can be adjusted by controlling the UV illumination. Double-walled TiO2 nanotubes or single-walled nanotubes can be selectively formed by switching on/off the UV illumination. The thickness of the inner and outer walls of the double-walled nanotubes can be tailored by changing the UV power. Due to their larger surface areas compared to single-walled nanotubes, the porous double-walled nanotubes exhibit an enhanced photo-degradation rate for methylene blue (MB). The mechanism of the porous double-walled TiO2 nanotubes is proposed based on the photoactive semiconducting property of the as-growing TiO2 nanotubes under UV. Electronic supplementary information (ESI) available

  7. Improvement of solar energy conversion with Nb-incorporated TiO2 hierarchical microspheres.

    PubMed

    Hoang, Son; Ngo, Thong Q; Berglund, Sean P; Fullon, Raymond R; Ekerdt, John G; Mullins, C Buddie

    2013-07-22

    Niobium-modified TiO2 hierarchical spherical micrometer-size particles, which consist of many nanowires, are synthesized by solvothermal synthesis and studied as photoelectrodes for water photo-oxidation and dye-sensitized solar cell (DSSC) applications. Incorporation of Nb leads to a rutile-to-anatase TiO2 phase transition in the TiO2 hierarchical spheres (HSs), with the anatase percentage increasing from 0% for the pristine TiO2 HSs to 47.6% for the 1.82 at.% Nb-incorporated TiO2 sample. Incorporation of Nb leads to significant improvements in water photo-oxidation with the photocurrents reaching 70.5 μA cm(-2) at 1.23 V versus the reversible hydrogen electrode, compared with 28.3 μA cm(-2) for the pristine TiO2 sample. The photoconversion efficiency of Nb:TiO2 HS-based DSSCs reaches 6.09±0.15% at 0.25 at.% Nb, significantly higher than that for the pristine TiO2 HS cells (3.99±0.02%). In addition, the incident-photon-to-current efficiency spectra for DSSCs show that employing TiO2 and Nb:TiO2 HSs provides better light harvesting, especially of long-wavelength photons, than anatase TiO2 nanoparticle-based DSSCs.

  8. Synthesis and growth mechanism of multilayer TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Guan, Dongsheng; Wang, Ying

    2012-04-01

    High-aspect-ratio TiO2 nanotube arrays formed by anodic oxidation have drawn extensive attention due to their easy fabrication and various excellent optical, electrical and biomedical properties. In contrast to conventional single-layer TiO2 nanotubes prepared via constant-voltage anodization, we synthesize multilayer TiO2 nanotube arrays with high surface area by using alternating-voltage anodization steps. This work presents synthesis and growth mechanisms of single-layer smooth TiO2 nanotubes, bamboo-type nanotubes and double-layer nanotubes, by tuning various parameters such as voltage, time, and water content in the electrolyte. It is found that ion diffusion inside the nanotubes dominates growth of these three structures. A stable pH and ion-diffusion profile allows the steady growth of smooth TiO2 tubes in NH4F-containing ethylene glycol (EG). The addition of a low-voltage anodization step reduces the pH and ion-diffusion gradient in the nanotubes and induces formation of bamboo-type nanotubes and double-layer nanotubes when a second high-voltage anodization is conducted. Ion diffusion through a nanotube takes time; thus formation of lower-layer TO2 nanotubes costs more time if longer nanotubes are grown in the upper layer, since ions diffuse through these longer nanotubes. This ion-diffusion controlled growth mechanism is further confirmed by tailoring the water content (0-20 vol%) in the electrolyte and the voltage gaps to control the time needed for initiation of lower-layer TiO2 nanotube arrays. The fundamental understanding of the growth characteristics of double-layer TiO2 nanotubes presented in this paper offers us more flexibility in engineering morphology, tuning dimensions and phase compositions of multilayer TiO2 nanotubes. In addition, we synthesize double-layer TiO2 nanotube arrays composed of one layer of anatase phase and another layer of amorphous phase.High-aspect-ratio TiO2 nanotube arrays formed by anodic oxidation have drawn extensive

  9. Enhanced photocatalytic activity in anodized WO3-loaded TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Nazari, M.; Golestani-Fard, F.; Bayati, R.; Eftekhari-Yekta, B.

    2015-04-01

    In this work, TiO2 and WO3-grafted TiO2 nanotubes were grown via anodizing of titanium substrates in tungstate containing electrolytes. The samples were characterized in detail by XRD, XPS, SEM, EDX, and UV-Vis spectrophotometry techniques. Besides, photocatalytic characteristics were evaluated through measuring the degradation rate of 4-chlorophenol to establish a correlation between structure and photochemical properties. We were able to control morphology and growth mode of nanotubes from a tubular to a worm-like structure by changing the electrolyte composition. The samples possessed an anatase-rutile matrix where the anatase/rutile ratio was found to increase with the concentration of tungstate in the electrolyte. We attributed this observation to change in electrical conductivity of the electrolyte and the heat generated on the substrates. It was unambiguously revealed that a composite of WO3 and TiO2 forms and, in parallel, tungsten is doped into the crystalline lattice of TiO2. The maximum photocatalytic reaction rate constant for TiO2 and WO3-TiO2 samples was determined to be 0.0131 and 0.0174 min-1 respectively. The grafting TiO2 nanotubes with WO3 enhances the photocatalytic activity mainly due to the hindrance of charge carrier recombination and the formation of a more acidic surface. We established a correlation between structure, stoichiometry, and photocatalytic characteristics of nanotubes.

  10. Free-standing arrays of isolated TiO2 nanotubes through supercritical fluid drying.

    PubMed

    Deneault, James R; Xiao, Xiaoyin; Kang, Tae-Sik; Wang, Joanna S; Wai, Chien M; Brown, Gail J; Durstock, Michael F

    2012-01-16

    A common complication in fabricating arrays of TiO(2) nanotubes is that they agglomerate into tightly packed bundles during the inevitable solvent evaporation step. This problem is particularly acute for template-fabricated TiO(2) nanotubes, as the geometric tunability of this technique enables relatively large inter-pore spacings or, from another perspective, more space for lateral displacement. Our work showed that agglomeration results from the surface tension forces that are present as the ambient solvent is evaporated from the nanotube film. Herein, we report a processing and fabrication approach that utilizes supercritical fluid drying (CO(2)) to prepare arrays of template-fabricated TiO(2) nanotubes that are free-standing and spatially isolated. This approach could be beneficial to many emerging technologies, such as solid-state dye-sensitized solar cells and vertically-oriented carbon nanotube electrodes.

  11. Interface feature characterization and Schottky interfacial layer confirmation of TiO2 nanotube array film

    NASA Astrophysics Data System (ADS)

    Li, Hongchao; Tang, Ningxin; Yang, Hongzhi; Leng, Xian; Zou, Jianpeng

    2015-11-01

    We report here characterization of the interfacial microstructure and properties of titanium dioxide (TiO2) 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 TiO2 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 TiO2 nanotube arrays occurs in four stages: barrier layer formation, penetrating micropore formation, regular nanotube formation, and nanofiber formation. The TiO2 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 TiO2 nanotube film was amorphous and the Ti substrate was highly crystallized with many dislocation walls.

  12. Preparation of near micrometer-sized TiO2 nanotube arrays by high voltage anodization.

    PubMed

    Ni, Jiahua; Noh, Kunbae; Frandsen, Christine J; Kong, Seong Deok; He, Guo; Tang, Tingting; Jin, Sungho

    2013-01-01

    Highly ordered TiO2 nanotube arrays with large diameter of 680-750 nm have been prepared by high voltage anodization in an electrolyte containing ethylene glycol at room temperature. To effectively suppress dielectric breakdown due to high voltage, pre-anodized TiO2 film was formed prior to the main anodizing process. Vertically aligned, large sized TiO2 nanotubes with double-wall structure have been demonstrated by SEM in detail under various anodizing voltages up to 225 V. The interface between the inner and outer walls in the double-wall configuration is porous. Surface topography of the large diameter TiO2 nanotube array is substantially improved and effective control of the growth of large diameter TiO2 nanotube array is achieved. Interestingly, the hemispherical barrier layer located at the bottom of TiO2 nanotubes formed in this work has crinkles analogous to the morphology of the brain cortex. These structures are potentially useful for orthopedic implants, storage of biological agents for controlled release, and solar cell applications.

  13. Investigating the antifungal activity of TiO2 nanoparticles deposited on branched carbon nanotube arrays

    NASA Astrophysics Data System (ADS)

    Darbari, S.; Abdi, Y.; Haghighi, F.; Mohajerzadeh, S.; Haghighi, N.

    2011-06-01

    Branched carbon nanotube (CNT) arrays were synthesized by plasma-enhanced chemical vapour deposition on a silicon substrate. Ni was used as the catalyst and played an important role in the realization of branches in vertically aligned nanotubes. TiO2 nanoparticles on the branched CNTs were produced by atmospheric pressure chemical vapour deposition followed by a 500 °C annealing step. Transmission and scanning electron microscopic techniques were used to study the morphology of the TiO2/branched CNT structures while x-ray diffraction and Raman spectroscopy were used to verify the characteristics of the prepared nanostructures. Their antifungal effect on Candida albicans biofilms under visible light was investigated and compared with the activity of TiO2/CNT arrays and thin films of TiO2. The TiO2/branched CNTs showed a highly improved photocatalytic antifungal activity in comparison with the TiO2/CNTs and TiO2 film. The excellent visible light-induced photocatalytic antifungal activity of the TiO2/branched CNTs was attributed to the generation of electron-hole pairs by visible light excitation with a low recombination rate, in addition to the high surface area provided for the interaction between the cells and the nanostructures. Scanning electron microscopy was used to observe the resulting morphological changes in the cell body of the biofilms existing on the antifungal samples.

  14. Surface modification of TiO2 nanotubes with osteogenic growth peptide to enhance osteoblast differentiation.

    PubMed

    Lai, Min; Jin, Ziyang; Su, Zhiguo

    2017-04-01

    To investigate the influence of surface-biofunctionalized substrates on osteoblast behavior, a layer of aligned TiO2 nanotubes with a diameter of around 70nm was fabricated on titanium surface by anodization, and then osteogenic growth peptide (OGP) was conjugated onto TiO2 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 TiO2 nanotube substrates on the morphology, proliferation and differentiation of osteoblasts were examined in vitro. Immunofluorescence staining revealed that the OGP-functionalized TiO2 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 TiO2 nanotubes showed significantly higher (p<0.05 or p<0.01) levels of alkaline phosphatase (ALP) and mineralization after 4, 7 and 14days of culture, respectively. Cells grown on OGP-functionalized TiO2 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 14days of culture. These data suggest that surface functionalization of TiO2 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.

  15. Tailoring of antibacterial Ag nanostructures on TiO2 nanotube layers by magnetron sputtering.

    PubMed

    Uhm, Soo-Hyuk; Song, Doo-Hoon; Kwon, Jae-Sung; Lee, Sang-Bae; Han, Jeon-Geon; Kim, Kyoung-Nam

    2014-04-01

    To reduce the incidence of postsurgical bacterial infection that may cause implantation failure at the implant-bone interface, surface treatment of titanium implants with antibiotic materials such as silver (Ag) has been proposed. The purpose of this work was to create TiO2 nanotubes using plasma electrolytic oxidation (PEO), followed by formation of an antibacterial Ag nanostructure coating on the TiO2 nanotube layer using a magnetron sputtering system. PEO was performed on commercially pure Ti sheets. The Ag nanostructure was added onto the resulting TiO2 nanotube using magnetron sputtering at varying deposition rates. Field emission scanning electron microscopy and transmission electron microscopy were used to characterize the surface, and Ag content on the TiO2 nanotube layer was analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. Scanning probe microscopy for surface roughness and contact angle measurement were used to indirectly confirm enhanced TiO2 nanotube hydrophilicity. Antibacterial activity of Ag ions in solution was determined by inductively coupled plasma mass spectrometry and antibacterial testing against Staphylococcus aureus (S. aureus). In vitro, TiO2 nanotubes coated with sputtered Ag resulted in significantly reduced S. aureus. Cell viability assays showed no toxicity for the lowest sputtering time group in the osteoblastic cell line MC3T3-E1. These results suggest that a multinanostructured layer with a biocompatible TiO2 nanotube and antimicrobial Ag coating is a promising biomaterial that can be tailored with magnetron sputtering for optimal performance.

  16. Microwave assisted rapid and complete degradation of atrazine using TiO(2) nanotube photocatalyst suspensions.

    PubMed

    Zhanqi, Gao; Shaogui, Yang; Na, Ta; Cheng, Sun

    2007-07-16

    A technology, microwave-assisted photocatalysis on TiO(2) nanotubes, which can be applied to degrade atrazine rapidly and completely, was investigated. TiO(2) nanotubes were prepared, and confirmed by XRD, TEM and ESR. Microwave-assisted photocatalytic degradation of atrazine in aqueous solution was investigated. The result indicates that atrazine is completely degraded in 5min and the mineralization efficiency is 98.5% in 20min, which is obviously more efficient than that by the traditional photocatalytic degradation methods. It may be attributed to the intense UV radiation generated by electrodeless discharge lamps under microwave irradiation, the increased number of OH, additional defect sites on TiO(2) under the irradiation of microwave and larger specific surface area of TiO(2) nanotubes which could adsorb more organic substances to degrade than TiO(2) nanoparticles. Along with the degradation of atrazine, the concentrations of Cl(-) and NO(3)(-) increase gradually. In 20min [Cl(-)] and [NO(3)(-)] are 3, 27.8mg/L, respectively, which are close to their stoichiometric values. The major intermediates of atrazine were identified by HPLC/MS and possible degradation pathways of atrazine in microwave-assisted photocatalysis on TiO(2) nanotubes were proposed.

  17. Structure -- Magnetic Property Correlations in TiO 2 Nanotube Arrays

    NASA Astrophysics Data System (ADS)

    Mohammad Hosseinpour, Pegah

    TiO2 nanotube arrays are promising candidates for applications such as photocatalysis and for potential employment in spin-electronic (spintronic) devices. The functionality of TiO2-based nanotubes is highly dependent on their structure (microstructure and crystallographic symmetry) and magnetic properties. Unified understanding of the influence of these factors on the electronic structure of TiO2 is of paramount importance towards engineering these materials. This Dissertation aims at investigating the correlations of the morphology, crystallinity, crystal structure, electronic structure and magnetic properties of TiO2 nanotubes, with potential relevance to their functionality. Self-ordered arrays of amorphous TiO2 nanotubes (pure and Fe-doped with cationic concentration of ~2.1 at%) were synthesized by the electrochemical anodization technique, followed by subjecting them to thermal treatments up to 450 °C to crystallize these nanostructures. A variety of probes---morphological, structural, magnetic and spectroscopic---were used to characterize the properties of these nanostructures as functions of their processing conditions and the dopant content. Structure-functionality relationships in these nanostructures were verified by examining the photodegradation rate of methyl orange (a model water pollutant) in presence of TiO2 nanotubes under UV-Visible light irradiation. Results from this Dissertation research demonstrated that post-synthesis processing conditions---specifically, the nature of the annealing environment, as well as the presence of an external dopant, can alter the crystal structure and local electronic environment in TiO2 nanotubes, with subsequent effects on the magnetic properties of these nanostructures. The fundamental knowledge obtained in this research, on the interrelations of structural-magnetic properties and their potential influence on the functionality of TiO 2-based nanotubes, can be extended to the metal oxide semiconducting systems

  18. One‐dimensional TiO2 Nanotube Photocatalysts for Solar Water Splitting

    PubMed Central

    Ge, Mingzheng; Li, Qingsong; Cao, Chunyan; Huang, Jianying; Li, Shuhui; Zhang, Songnan; Chen, Zhong; Zhang, Keqin; Al‐Deyab, Salem S.

    2016-01-01

    Hydrogen production from water splitting by photo/photoelectron‐catalytic process is a promising route to solve both fossil fuel depletion and environmental pollution at the same time. Titanium dioxide (TiO2) nanotubes have attracted much interest due to their large specific surface area and highly ordered structure, which has led to promising potential applications in photocatalytic degradation, photoreduction of CO2, water splitting, supercapacitors, dye‐sensitized solar cells, lithium‐ion batteries and biomedical devices. Nanotubes can be fabricated via facile hydrothermal method, solvothermal method, template technique and electrochemical anodic oxidation. In this report, we provide a comprehensive review on recent progress of the synthesis and modification of TiO2 nanotubes to be used for photo/photoelectro‐catalytic water splitting. The future development of TiO2 nanotubes is also discussed. PMID:28105391

  19. One-dimensional TiO2 Nanotube Photocatalysts for Solar Water Splitting.

    PubMed

    Ge, Mingzheng; Li, Qingsong; Cao, Chunyan; Huang, Jianying; Li, Shuhui; Zhang, Songnan; Chen, Zhong; Zhang, Keqin; Al-Deyab, Salem S; Lai, Yuekun

    2017-01-01

    Hydrogen production from water splitting by photo/photoelectron-catalytic process is a promising route to solve both fossil fuel depletion and environmental pollution at the same time. Titanium dioxide (TiO2) nanotubes have attracted much interest due to their large specific surface area and highly ordered structure, which has led to promising potential applications in photocatalytic degradation, photoreduction of CO2, water splitting, supercapacitors, dye-sensitized solar cells, lithium-ion batteries and biomedical devices. Nanotubes can be fabricated via facile hydrothermal method, solvothermal method, template technique and electrochemical anodic oxidation. In this report, we provide a comprehensive review on recent progress of the synthesis and modification of TiO2 nanotubes to be used for photo/photoelectro-catalytic water splitting. The future development of TiO2 nanotubes is also discussed.

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

    NASA Astrophysics Data System (ADS)

    Xie, Yi; Heo, Sung Hwan; Yoo, Seung Hwa; Ali, Ghafar; Cho, Sung Oh

    2010-03-01

    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.

  1. Effect of construction of TiO2 nanotubes on platelet behaviors: Structure-property relationships.

    PubMed

    Huang, Qiaoling; Yang, Yun; Zheng, Dajiang; Song, Ran; Zhang, Yanmei; Jiang, Pinliang; Vogler, Erwin A; Lin, Changjian

    2017-03-15

    Blood compatibility of TiO2 nanotubes (TNTs) has been assessed in rabbit platelet-rich plasma (PRP), which combines activation of both blood plasma coagulation and platelets. We find that (i) amorphous TiO2 nanotubes (TNTs) with relatively larger outer diameters led to reduced platelet adhesion/activation, (ii) TNTs with relatively smaller outer diameters in a predominately rutile phase also inhibited platelet adhesion and activation, and (iii) a pervasive fibrin network formed on larger outer diameter TNTs in a predominately anatase phase. Thus, this study suggests that combined effect of crystalline phase and surface chemistry controls blood-contact behavior of TNTs. A more comprehensive mechanism is proposed for understanding hemocompatibility of TiO2 which might prove helpful as a guide to prospective design of TiO2-based biomaterials.

  2. WO3/TiO2 nanotube photoanodes for solar water splitting with simultaneous wastewater treatment.

    SciTech Connect

    Reyes, Karla Rosa; Robinson, David B.

    2013-05-01

    Nanostructured WO3/TiO2 nanotubes with properties that enhance solar photoconversion reactions were developed, characterized and tested. The TiO2 nanotubes were prepared by anodization of Ti foil, and WO3 was electrodeposited on top of the nanotubes. SEM images show that these materials have the same ordered structure as TiO2 nanotubes, with an external nanostructured WO3 layer. Diffuse reflectance spectra showed an increase in the visible absorption relative to bare TiO2 nanotubes, and in the UV absorption relative to bare WO3 films. Incident simulated solar photon-to-current efficiency increased from 30% (for bare WO3) to 50% (for WO3/TiO2 composites). With the addition of diverse organic pollutants, the photocurrent densities exhibited more than a 5-fold increase. Chemical oxygen demand measurements showed the simultaneous photodegradation of organic pollutants. The results of this work indicate that the unique structure and composition of these composite materials enhance the charge carrier transport and optical properties compared with the parent materials.

  3. HOS cell adhesion on TiO2 nanotubes texturized by laser engraving

    NASA Astrophysics Data System (ADS)

    Sandoval Amador, A.; Montañez Supelano, N. D.; Arias, A. M. Vera; Escobar Rivero, P.; Peña Ballesteros, D. Y.

    2017-01-01

    Due to its outstanding properties, the titanium and its alloys have been widely used in the dental and orthopaedic fields as biomaterials. The TiO2 nanotubes surface and the texturized process by laser engraving enables significantly accelerated osteoblast adhesion on the biomaterial. For this reason in this paper, the HOS cell responses on TiO2 nanotubes fabricated on Ti6Al4V alloy and texturized by laser engraving were evaluated. The test surfaces were carried out on smooth Ti6Al4V as control, TiO2 nanotubes (NT) and surfaces with micropoints obtained by laser engraving, with 1mm spacing (NTP1) and 0.5mm (NTP2). The results show that the texturized process enables decreases the contact angle thus improving wettability of the TiO2 nanotubes surface. The NTP1 and NTP2 surfaces show excellent cell adhesion and spreading on the surface, which is evident in epifluorescence microscopy images. Furthermore, the NTP1 and NTP2 surfaces improved the cell proliferation at 18% and 16% respectively in relation with NT surface, showing that the laser texturing improves cell response of TiO2 nanotubes.

  4. Nanoindentation study of the mechanical behavior of TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    Titanium dioxide (TiO2) 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 TiO2 nanotube arrays is not well understood. In this work, we investigate the deformation and failure of TiO2 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 TiO2 nanotube arrays by Berkovich and conical indenters are closely associated with the densification of TiO2 nanotubes under compression. A theoretical model for deformation of the arrays under a large-radius conical indenter is also proposed.

  5. Engineering bamboo-type TiO2 nanotube arrays to enhance their photocatalytic property.

    PubMed

    Guan, Dongsheng; Hymel, Paul J; Zhou, Chengjun; Wang, Ying

    2014-06-01

    Bamboo-type TiO2 nanotube arrays with high surface area can be synthesized by alternating voltage (AV) anodization for their important use as photocatalytic medium. Their morphologies are highly dependent on preparation parameters including anodization time and electrolyte composition. Minimum time of high-voltage steps required for forming desired bamboo ridge spacing on these nanotubes can be calculated from current-time profiles recorded during potentiostatic anodization at the voltage. Water content in NH4F-containing ethylene glycol (EG) electrolytes is optimized simply from analyses of current transients or current-voltage relations for anodization in EG electrolytes with different amount of water, in order to achieve efficient electrochemical growth of TiO2 nanotubes for large ridge density and long tube length. Two types of bamboo-type TiO2 nanotubes with the same length of 5.46 microm but different ridge spacing are synthesized for photocatalytic degradation of methylene blue (MB) under UV radiation. Both of the bamboo-type nanotube arrays show improved photo catalysis compared to smooth TiO2 nanotubes of the same length, due to their larger surface area favorable for heterogeneous catalytic processes. In particular, the apparent rate constant of photocatalytic degradation on bamboo-type nanotubes is up to 29.4% higher than that for degradation on smooth ones.

  6. The Effect of Carbon Nanotube on Band Gap Energy of TiO2 Nanoparticles

    NASA Astrophysics Data System (ADS)

    Taleshi, F.

    2015-05-01

    A composite of TiO2-carbon nanotubes (CNTs) was synthesized via a sol-gel method. The structure and morphology of the nanocomposite samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The optical properties of the samples were studied using UV-Vis spectroscopy. The results show that CNTs can decrease the value of band gap energy of TiO2 nanoparticles considerably.

  7. Electrophoretic Deposition of Carbon Nanotubes over TiO2 Nanotubes: Evaluation of Surface Properties and Biocompatibility

    PubMed Central

    Park, Jung Eun; Park, Il Song; Bae, Tae Sung; Lee, Min Ho

    2014-01-01

    Titanium (Ti) is often used as an orthopedic and dental implant material due to its better mechanical properties, corrosion resistance, and excellent biocompatibility. Formation of TiO2 nanotubes (TiO2 NTs) on titanium is an interesting surface modification to achieve controlled drug delivery and to promote cell growth. Carbon nanotubes (CNTs) possess excellent chemical durability and mechanical strength. The use of CNTs in biomedical applications such as scaffolds has received considerable attention in recent years. The present study aims to modify the surface of titanium by anodizing to form TiO2 NTs and subsequently deposit CNTs over it by electrophoretic deposition (EPD). Characteristic, biocompatibility, and apatite forming ability of the surface modified samples were evaluated. The results of the study reveal that CNTs coating on TiO2 nanotubes help improve the biological activity and this type of surface modification is highly suitable for biomedical applications. PMID:25093017

  8. TiO2 Nanotubes: Recent Advances in Synthesis and Gas Sensing Properties

    PubMed Central

    Galstyan, Vardan; Comini, Elisabetta; Faglia, Guido; Sberveglieri, Giorgio

    2013-01-01

    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. PMID:24184919

  9. Photoelectrochemical characterization of dual-layered anodic TiO2 nanotubes with honeycomb morphology

    NASA Astrophysics Data System (ADS)

    Sitler, S. J.; Raja, K. S.; Karmiol, Z.; Chidambaram, D.

    2017-01-01

    Titanium dioxide (TiO2) nanotubes having a novel honeycomb like morphology were synthesized by a two-step anodization process and characterized for photoelectrochemical behavior. The titania nanotubes with honeycomb morphology showed at least 32% higher photocurrent density than the regular vertically oriented titania nanotubes at any given bias potential. The enhanced photoactivity of the honeycomb morphology was attributed to the better charge transport properties and the presence of a hemispherical surface morphology that enhanced the light harvesting behavior.

  10. Visible-light-induced photoelectrochemical behaviors of Fe-modified TiO2 nanotube arrays.

    PubMed

    Xu, Zhihua; Yu, Jiaguo

    2011-08-01

    Fe-modified TiO(2) nanotube arrays (TiO(2) NTs) were prepared by annealing amorphous TiO(2) NTs whose surface was covered with Fe(3+) by a dip-coating procedure, and characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and UV-visible reflectance spectroscopy. The photoelectrochemical properties were evaluated by the photocurrent response and photoelectrocatalytic (PEC) degradation of methylene orange (MO) and 4-chlorophenol in water under visible-light irradiation (λ > 420 nm). The results showed that a Fe-modified TiO(2) NTs electrode exhibited a larger photocurrent response and higher PEC activity for the degradation of organic pollutants than a pure TiO(2) NTs electrode. At a bias potential of 0.4 V, the photocurrent response of a 0.5 M Fe-modified TiO(2) NTs electrode exceeded that of a pure TiO(2) NTs electrode by a factor of about 10, and the PEC degradation rates of MO and 4-chlorophenol on a 0.5 M Fe-modified TiO(2) NTs electrode exceeded those on a pure TiO(2) NTs electrode by a factor of about 2.5. The larger photocurrent response and higher PEC activity of Fe-modified TiO(2) NTs could be attributed to the enhancement of separation of charge-carriers at the external electric field and the extension of the light response range of TiO(2) to the visible-light region with the narrowing of the band gap.

  11. TiO2 nanotube array sensor for detecting the SF6 decomposition product SO2.

    PubMed

    Zhang, Xiaoxing; Zhang, Jinbin; Jia, Yichao; Xiao, Peng; Tang, Ju

    2012-01-01

    The detection of partial discharge through analysis of SF(6) gas components in gas-insulated switchgear, is significant for the diagnosis and assessment of the operating state of power equipment. The present study proposes the use of a TiO(2) nanotube array sensor for detecting the SF(6) decomposition product SO(2), and the application of the anodic oxidation method for the directional growth of highly ordered TiO(2) nanotube arrays. The sensor response of 10-50 ppm SO(2) gas is tested, and the sensitive response mechanism is discussed. The test results show that the TiO(2) nanotube sensor array has good response to SO(2) gas, and by ultraviolet radiation, the sensor can remove attached components very efficiently, shorten recovery time, reduce chemical poisoning, and prolong the life of the components.

  12. A novel drug delivery of 5-fluorouracil device based on TiO2/ZnS nanotubes.

    PubMed

    Faria, Henrique Antonio Mendonça; de Queiroz, Alvaro Antonio Alencar

    2015-11-01

    The structural and electronic properties of titanium oxide nanotubes (TiO2) have attracted considerable attention for the development of therapeutic devices and imaging probes for nanomedicine. However, the fluorescence response of TiO2 has typically been within ultraviolet spectrum. In this study, the surface modification of TiO2 nanotubes with ZnS quantum dots was found to produce a red shift in the ultra violet emission band. The TiO2 nanotubes used in this work were obtained by sol-gel template synthesis. The ZnS quantum dots were deposited onto TiO2 nanotube surface by a micelle-template inducing reaction. The structure and morphology of the resulting hybrid TiO2/ZnS nanotubes were investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction techniques. According to the results of fluorescence spectroscopy, pure TiO2 nanotubes exhibited a high emission at 380nm (3.26eV), whereas TiO2/ZnS exhibited an emission at 410nm (3.02eV). The TiO2/ZnS nanotubes demonstrated good bio-imaging ability on sycamore cultured plant cells. The biocompatibility against mammalian cells (Chinese Hamster Ovarian Cells-CHO) suggesting that TiO2/ZnS may also have suitable optical properties for use as biological markers in diagnostic medicine. The drug release characteristic of TiO2/ZnS nanotubes was explored using 5-fluorouracil (5-FU), an anticancer drug used in photodynamic therapy. The results show that the TiO2/ZnS nanotubes are a promising candidate for anticancer drug delivery systems.

  13. Positive role of incorporating P-25 TiO2 to mesoporous-assembled TiO2 thin films for improving photocatalytic dye degradation efficiency.

    PubMed

    Sreethawong, Thammanoon; Ngamsinlapasathian, Supachai; Yoshikawa, Susumu

    2014-09-15

    In this work, a simple and effective strategy to improve the photocatalytic dye degradation efficiency of the mesoporous-assembled TiO2 nanoparticle thin films by incorporating small contents of commercial P-25 TiO2 during the thin film preparation was developed. The mesoporous-assembled TiO2 nanoparticles were synthesized by a sol-gel method with the aid of a mesopore-directing surfactant, followed by homogeneously mixing with P-25 TiO2 prior to the thin film coating on glass substrate. The mesoporous-assembled TiO2 film with 5 wt.% P-25 TiO2 incorporation and calcined at 400°C provided an improved photocatalytic Acid Black (AB) dye degradation efficiency. The increase in number of coated layers to the optimum four layers of the aforementioned film was found to further improve the degradation efficiency. The recyclability test of this 5 wt.% P-25 TiO2-incorporated mesoporous-assembled TiO2 film with four coated layers revealed that it can be reused for multiple cycles without a requirement of post-treatment while the degradation efficiency was retained.

  14. Flexible symmetric supercapacitors based on vertical TiO2 and carbon nanotubes

    NASA Astrophysics Data System (ADS)

    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.

  15. Ultrafast Room-Temperature Crystallization of TiO2 Nanotubes Exploiting Water-Vapor Treatment

    NASA Astrophysics Data System (ADS)

    Lamberti, Andrea; Chiodoni, Angelica; Shahzad, Nadia; Bianco, Stefano; Quaglio, Marzia; Pirri, Candido F.

    2015-01-01

    In this manuscript a near-room temperature crystallization process of anodic nanotubes from amorphous TiO2 to anatase phase with a fast 30 minutes treatment is reported for the first time. This method involves the exposure of as-grown TiO2 nanotubes to water vapor flow in ambient atmosphere. The water vapor-crystallized samples are deeply investigated in order to gain a whole understanding of their structural, physical and chemical properties. The photocatalytic activity of the converted material is tested by dye degradation experiment and the obtained performance confirms the highly promising properties of this low-temperature processed material.

  16. Photo-electro-catalytic performance of highly ordered nitrogen doped TiO2 nanotubes array photoanode

    NASA Astrophysics Data System (ADS)

    Aritonang, Anthoni B.; Surahman, Hedi; Krisnandi, Yuni K.; Gunlazuardi, Jarnuzi

    2017-02-01

    Highly ordered nitrogen doped TiO2 nanotube arrays (N-TNTAs) were synthesized via a one step anodization method at 40 V for 1 hour, in the electrolyte containing ammonium fluoride (NH4F), water and triethylamine solution, followed calcination under N2 atmosphere at 450oC for 3 h. The obtained samples were characterized by means of FE-SEM image showed that the N-TNTs are in a highly ordered array, having inner diameters, wall thickness, tube length of 65 nm, 30 nm and 900 nm, respectively. The X-ray diffraction (XRD) patterns of N-TNTAs and undoped TiO2 nanotubes arrays (TNTAs) are identical consists of anatase phase, which suggests that the doping of N does not affect the crystalline structure. X-ray photoelectron spectroscopy (XPS), revealed that N atom was incorporated into the lattice of a TiO2 nanotube array film. The infrared spectra, showed a new peak at 1240 cm-1 may indicate the incorporation of N into the lattice of TiO2 through substituting O atoms, in the form of ∼N-Ti-O∼. A red shift of the absorption edge toward the visible region of N-TNTAs are observed by diffuse reflectance spectroscopy (DRS), which is corresponding to a band gap of 2.8 eV. The photo-electro-catalytic (PEC) degradation efficiency toward methylene blue solution under visible light illumination of the N-TNTAs electrode was 89%, in which the rate constant of N-TNTAs electrode was 8 times better compared to that the undoped TNTAs photo-electrode.

  17. Amorphous TiO2 nanotube-derived synthesis of highly ordered anatase TiO2 nanorod arrays

    NASA Astrophysics Data System (ADS)

    Zhao, Cong; Zhu, Dachuan; Cao, Shixiu

    2016-02-01

    A facile method by combining anodic oxidation and hydrothermal method was developed to construct highly ordered anatase TiO2 nanorods (TNRs) and nanotubes (TNTs). In this method, the anodic oxidation was used for preparing highly ordered amorphous TNTs, which subsequently served as highly ordered template for next reaction process. Upon hydrothermal treatment, the as-anodized amorphous template got converted to highly ordered anatase TNTs (blank sample) in without cobalt nitrate solution and TNRs (doped sample) in cobalt nitrate solution, respectively. To our best knowledge, this is first successful attempt to prepare highly ordered anatase TNRs based on the above amorphous template. The scanning electron microscope (SEM) and transmission electron microscope (TEM) observations indicate that the as-prepared anatase TNRs are composed by a large number of anatase TiO2 nanoparticles (TNPs) and the morphology at top of TNRs is different from that of its trunk. Details of the morphology, phase transformation, and growth mechanism of the obtained TNRs are discussed. In addition, the role of Co2+ in the crystallization process had been also discussed.

  18. Super-long aligned TiO2/carbon nanotube arrays

    NASA Astrophysics Data System (ADS)

    Zhao, Yang; Hu, Yue; Li, Yan; Zhang, Han; Zhang, Shaowen; Qu, Liangti; Shi, Gaoquan; Dai, Liming

    2010-12-01

    5 mm long aligned titanium oxide/carbon nanotube (TiO2/CNT) coaxial nanowire arrays have been prepared by electrochemically coating the constituent CNTs with a uniform layer of highly crystalline anatase TiO2 nanoparticles. While the presence of the TiO2 coating was confirmed by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and x-ray diffraction, the resultant TiO2/CNT coaxial arrays were demonstrated to exhibit minimized recombination of photoinduced electron-hole pairs and fast electron transfer from the long TiO2/CNT arrays to external circuits. This, in conjunction with the aligned macrostructure, facilitates the fabrication of TiO2/CNT arrays for various device applications, ranging from photodetectors to photocatalytic systems. Thus, the millimeter long TiO2/CNT arrays represent a significant advance in the development of new macroscopic photoelectronic nanomaterials attractive for a variety of device applications beyond those demonstrated in this study.

  19. Mechanisms of stem cell osteogenic differentiation on TiO2 nanotubes.

    PubMed

    Yu, Weiqiang; Qian, Chao; Jiang, Xinquan; Zhang, Fuqiang; Weng, Weimin

    2015-12-01

    TiO2 nanotubes could stimulate osteogenic differentiation of stem cells, but the molecular mechanisms underlying the interactions between nanotubes and stem cells remain unclear. In this study, we investigated the response of bone marrow stromal cells to nanotubes of different diameters using microarray-based bioinformatics approach. Gene ontology (GO) and GO enrichment network analysis indicated that larger TiO2 nanotubes were more potent than smaller nanotubes in inducing the expression of genes involved in cell proliferation, differentiation, and immune responses, and inhibiting that of genes responsible for cell adhesion. The analysis of the signaling network containing significantly affected genes suggested that Na(+)/K(+) transporting ATPases ATP1A2 (alpha 2 polypeptide) and ATP1A3 (alpha 3 polypeptide), and MAP3K11 (mitogen-activated protein kinase kinase kinase 11) were important for inducing osteogenic differentiation of bone marrow stromal cells without additional osteogenic stimuli. The upregulation of the ATP1A2 and MAP3K11 genes confirmed by real-time PCR indicates that the response of bone marrow stromal cells to nanotube cues may be mediated by the pathways previously implicated in transducing mechanical stress signals. Our results revealed some molecular mechanisms by which TiO2 nanotubes may direct osteogenic differentiation of stem cells.

  20. Using Ag-embedded TiO2 nanotubes array as recyclable SERS substrate

    NASA Astrophysics Data System (ADS)

    Ling, Yunhan; Zhuo, Yuqing; Huang, Liang; Mao, Duolu

    2016-12-01

    A simple strategy for synthesizing Ag-loaded TiO2 nanotube film for use as multifunctional photocatalyst and recyclable surface-enhanced Raman scattering (SERS) substrate is introduced. Highly aligned TiO2 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.

  1. Dye-sensitized photovoltaic wires using highly ordered TiO2 nanotube arrays.

    PubMed

    Liu, Zhaoyue; Misra, Mano

    2010-04-27

    Dye-sensitized photovoltaic wires (DSPVWs) are developed using anodized Ti wires that contain ordered arrays of TiO2 nanotubes. The prototype DSPVW consists of N719 dye-adsorbed TiO2 nanotube arrays around a Ti wire as a working electrode, a platinum wire as a counter electrode, and an organic electrolyte encased in a capillary glass tube. The effect of length of nanotube arrays on the photovoltaic performance of DSPVWs is studied systematically. A solar-to-electric conversion efficiency of 2.78% is achieved with 55 microm long nanotubes under 98.3 mW/cm(2) AM 1.5 simulated full light. The prototype device is capable of achieving a long distance transport of photocurrent and harvesting all light from any direction in surroundings to generate electricity.

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

    PubMed

    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.

  3. TiO2-nanotube-based dye-sensitized solar cells containing fluorescent material.

    PubMed

    Kim, Woong-Rae; Lee, Young-Joon; Park, Hun; Lee, Jae-Joon; Choi, Won-Youl

    2013-05-01

    We fabricated a dye-sensitized solar cells (DSCs) with TiO2 nanotube arrays obtained by anodization of Ti foil. Vertical structure of TiO2 nanotube arrays is very attractive due to a high electron transfer from dye to electrode. To improve the power conversion efficiency, fluorescent material, F-6377, was applied in TiO2-nanotube-based DSCs to use a light spectrum efficiently. Fluorescent material was absorbed the different wavelength of 460 nm from the light absorbed by N719 dye. Fluorescent material to emit the absorbed light energy provided an additional light for dye in DSCs and additional electrons was generated. Thickness of TiO2 nanotube arrays grown by anodic oxidation was 15 microm. N719 dye and 13(-)/l(-) electrolyte were used to fabricate the DSCs. The short circuit current densities (J(sc)) and the power conversion efficiency in DSCs with fluorescent were 10.8 mA/cm2 and 2.48%, respectively. Electrochemical impedance spectroscopy (EIS) was observed to understand an electron transfer and life time.

  4. Exploring doxorubicin localization in eluting TiO2 nanotube arrays through fluorescence correlation spectroscopy analysis.

    PubMed

    De Santo, Ilaria; Sanguigno, Luigi; Causa, Filippo; Monetta, Tullio; Netti, Paolo A

    2012-11-07

    Drug elution properties of TiO(2) nanotube arrays have been largely investigated by means of solely macroscopic observations. Controversial elution performances have been reported so far and a clear comprehension of these phenomena is still missing as a consequence of a lack of molecular investigation methods. Here we propose a way to discern drug elution properties of nanotubes through the evaluation of drug localization by Fluorescence Correlation Spectroscopy (FCS) analysis. We verified this method upon doxorubicin elution from differently loaded TiO(2) nanotubes. Diverse elution profiles were obtained from nanotubes filled by soaking and wet vacuum impregnation methods. Impregnated nanotubes controlled drug diffusion up to thirty days, while soaked samples completed elution in seven days. FCS analysis of doxorubicin motion in loaded nanotubes clarified that more than 90% of drugs dwell preferentially in inter-nanotube spaces in soaked samples due to decorrelation in a 2D fashion, while a 97% fraction of molecules showed 1D mobility ascribable to displacements along the nanotube vertical axis of wet vacuum impregnated nanotubes. The diverse drug localizations inferred from FCS measurements, together with distinct drug-surface interaction strengths resulting from diverse drug filling techniques, could explain the variability in elution kinetics.

  5. Ultrasound aided photochemical synthesis of Ag loaded TiO2 nanotube arrays to enhance photocatalytic activity.

    PubMed

    Sun, Lan; Li, Jing; Wang, Chenglin; Li, Sifang; Lai, Yuekun; Chen, Hongbo; Lin, Changjian

    2009-11-15

    This work presents a novel approach for preparing TiO(2) nanotube array photocatalyst loaded with highly dispersed Ag nanoparticles through an ultrasound aided photochemical route. The Ag content loaded on the array was controlled by changing the concentration of AgNO(3) solution. The Ag-TiO(2) nanotube arrays were characterized by SEM, XRD, XPS and UV-vis absorption. The effects of Ag content on the photoelectrochemical (PEC) property and photocatalytic activity of TiO(2) nanotube array electrode were studied. The results showed that Ag loading significantly enhanced the photocurrent and photocatalytic degradation rate of TiO(2) nanotube array under UV-light irradiation. The photocurrent and photocatalytic degradation rate of Ag-TiO(2) nanotube array prepared in 0.006 M AgNO(3) solution were about 1.2 and 3.7 times as that of pure TiO(2) nanotube array, respectively.

  6. Facile fabrication, characterization, and enhanced photoelectrocatalytic degradation performance of highly oriented TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Zhao, Qidong; Li, Xinyong; Wang, Ning; Hou, Yang; Quan, Xie; Chen, Guohua

    2009-11-01

    Highly ordered TiO2 nanotube arrays were successfully fabricated using ethanol and water mixture electrolytes (40 vol% ethanol and 0.2 wt% hydrofluoric acid) by a facile electrochemical anodization method. The as-prepared nanotube arrays were grown perpendicular to the titanium substrate with about 90 nm in diameter, 20 nm in wall thickness, and around 500 nm in length. The formation mechanism of the samples is briefly discussed. A blue shift in the spectrum of UV-Vis absorption was observed with respect to a piece of the sol-gel derived TiO2 film. Moreover, photocurrent response and photoelectrocatalytic degradation of methyl orange under ultraviolet light irradiation were adopted to evaluate the photoelectrocatalytic properties of the TiO2 nanotube arrays. We demonstrate that the highly ordered TiO2 nanotube arrays possess much better photoelectrocatalytic activity than the sol-gel derived TiO2 film and good stability.

  7. Study on Fabrication and UV Photoelectric Property of TiO2 Nanotube Array Electrodes.

    PubMed

    Fu, Yao; Duan, Xiao-Long; Xing, Ming-Ming; Luo, Xi-Xian; Zhang, Ying-Hui; Liu, Wang

    2016-04-01

    Highly ordered TiO2 nanotube array electrodes were successfully fabricated by a two-step anodization method on Ti sheet substrates in an electrolyte composed of ammonium fluoride, deionized water, and glycol. The tube wall was smooth, and the average internal and external diameters, wall thickness, and tube length achieved were 80 nm, 90 nm, 10 nm, and 9 µm, respectively. X-ray diffraction and field emission scanning electron microscopy results revealed that the TiO2 nanotube arrays presented an amorphous structure. When calcined at 300 °C, the arrays crystallized into the anatase phase, and the crystallization degree of the oxide layer increased as the temperature rose. Calcinating at 400 °C did not obviously disrupt the porous structure of the highly ordered arrays. However, higher temperature enlarged the diameter of the nanotube array and roughened the tube wall. When the temperature reached 600 °C, the nanotube mouth broke because of the excessive stress, causing the oxide layer's thinness and nanotube mouth clogging. The photoelectric test showed that the electrode presented obvious photoresponse under 300-400 nm UV excitation (maximized at 360 nm). The degree of crystallization and the micro-structure of the oxide layer can significantly affect the photoelectric properties of the electrode. After calcination at 400 °C, the TiO2 nanotube arrays, with highly ordered tubular structure directly connected to the Ti substrate, can ensure the rapid transportation of photo-induced electrons to the Ti substrate, while the high crystallinity of the arrays can help reduce the defect density of the nanotube and extend the lifetime of the photo-induced carriers. The electrode showed the best photoelectric property, and the photocurrent intensity was maximized (29.6 µA). However, the calcination process with over-temperature resulted in substantial loss of the TiO2 oxide layer, mouth clogging, and a severe decline in the photoelectric properties.

  8. Gold nanoparticles-immobilized, hierarchically ordered, porous TiO2 nanotubes for biosensing of glutathione.

    PubMed

    Mers, Sv Sheen; Kumar, Elumalai Thambuswamy Deva; Ganesh, V

    2015-01-01

    Glutathione (GSH) is vital for several functions of our human body such as neutralization of free radicals and reactive oxygen compounds, maintaining the active forms of vitamin C and E, regulation of nitric oxide cycle, iron metabolism, etc. It is also an endogenous antioxidant in most of the biological reactions. Given the importance of GSH, a simple strategy is proposed in this work to develop a biosensor for quantitative detection of GSH. This particular biosensor comprises of gold nanoparticles (Au NPs)-immobilized, hierarchically ordered titanium dioxide (TiO2) porous nanotubes. Hexagonally arranged, honeycomb-like nanoporous tubular TiO2 electrodes are prepared by using a simple electrochemical anodization process by applying a constant potential of 30 V for 24 hours using ethylene glycol consisting of ammonium fluoride as an electrolytic medium. Structural morphology and crystalline nature of such TiO2 nanotubes are analyzed using field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). Interestingly, nanocomposites of TiO2 with Au NPs is prepared in an effort to alter the intrinsic properties of TiO2, especially tuning of its band gap. Au NPs are prepared by a well-known Brust and Schiffrin method and are immobilized onto TiO2 electrodes which act as a perfect electrochemical sensing platform for GSH detection. Structural characterization and analysis of these modified electrodes are performed using FESEM, XRD, and UV-visible spectroscopic studies. GSH binding events on Au NPs-immobilized porous TiO2 electrodes are monitored by electrochemical techniques, namely, cyclic voltammetry (CV) and chronoamperometry (CA). Several parameters such as sensitivity, selectivity, stability, limit of detection, etc are investigated. In addition, Au NPs dispersed in aqueous medium are also explored for naked-eye detection of GSH using UV-visible spectroscopy in order to compare the performance of the proposed sensor. Our studies clearly indicate

  9. Effect of alkali and heat treatments for bioactivity of TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Kim, Seo young; Kim, Yu kyoung; Park, Il song; Jin, Guang chun; Bae, Tae sung; Lee, Min ho

    2014-12-01

    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 TiO2 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 TiO2 nanotubes (PNA) and alkali and heat-treated TiO2 nanotubes (PNAH) groups. Cell proliferation was decreased due to the formation of amorphous sodium titanate (Na2TiO3) 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.

  10. An immutable array of TiO2 nanotubes to pressures over 30 GPa.

    PubMed

    Zhang, Yanyan; Wang, Qinglin; Zhang, Junkai; Wu, Xiaoxin; Ma, Yanzhang

    2017-04-07

    We report the successful formation of an immutable array of α-PbO2 phase TiO2 nanotubes by compression of a TiO2 nanotube array in an anatase phase. During compression to 31.3 GPa, the TiO2 nanotubes started to directly transform from an anatase phase to a baddeleyite phase at 14.5 GPa and completed the transition at 30.1 GPa. Under decompression, the baddeleyite phase transformed to an α-PbO2 phase at 4.6 GPa, which was quenchable to ambient pressure. Notably the tubular array microstructure was retained after the application of ultra high pressure and undergoing a series of phase transformations. Measurements indicated that the nanotubes in the array possessed higher compressibility than in the bulk form. The highly aligned array structure is believed to reinforce the nanotubes themselves, giving exceptional stability. This, as well as the wall thickness, may also account for their different phase transition pathway.

  11. An immutable array of TiO2 nanotubes to pressures over 30 GPa

    NASA Astrophysics Data System (ADS)

    Zhang, Yanyan; Wang, Qinglin; Zhang, Junkai; Wu, Xiaoxin; Ma, Yanzhang

    2017-04-01

    We report the successful formation of an immutable array of α-PbO2 phase TiO2 nanotubes by compression of a TiO2 nanotube array in an anatase phase. During compression to 31.3 GPa, the TiO2 nanotubes started to directly transform from an anatase phase to a baddeleyite phase at 14.5 GPa and completed the transition at 30.1 GPa. Under decompression, the baddeleyite phase transformed to an α-PbO2 phase at 4.6 GPa, which was quenchable to ambient pressure. Notably the tubular array microstructure was retained after the application of ultra high pressure and undergoing a series of phase transformations. Measurements indicated that the nanotubes in the array possessed higher compressibility than in the bulk form. The highly aligned array structure is believed to reinforce the nanotubes themselves, giving exceptional stability. This, as well as the wall thickness, may also account for their different phase transition pathway.

  12. [Preparation, characterization of Si doped TiO2 nanotubes and its application in photocatalytic oxidation of VOCs].

    PubMed

    Zou, Xue-Jun; Li, Xin-Yong; Qu, Zhen-Ping; Wang, Jiang-Jiang

    2011-12-01

    The Si-doped TiO2 nanotubes photocatalysts was synthesized by anodic oxidation method, which used Na2SiF6/HF as an electrolyte, and was characterized by means of SEM, XRD, DRS and EDX. TiO2 nanotubes composed of anatase phase and rutile phase, and Si was highly dispersed on the wall of TiO2 nanotubes. The photocatalytic activity of the Si-doped TiO2 nanotubes was investigated for photocatalytic degradation of gaseous toluene. It was found that the photocatalytic activity of Si-doped TiO2 nanotubes, which prepared by 0.03 mol x L x (-1) Na2SiF6/HF and calcined at 400 degrees C for 1 h, was the highest. The conversion of toluene was 60% over the prepared Si doped TiO2 nanotubes under UV light, which was one times higher than that of pure TiO2 nanotubes.

  13. Structural study of TiO2 nanotube based to the (101) anatase surface

    NASA Astrophysics Data System (ADS)

    Dargouthi, Sarra; Minot, Christian; Tangour, Bahoueddine

    2017-02-01

    This work concerns six TiO2 (n,0) nanotubes specifically: (9,0) (10,0) (11,0) (12,0) (13,0) and (14,0). They are obtained by winding a film from the (101) anatase surface, this plane surface serving as a reference. We show that the rolling up is a destabilizing factor. Indeed, the winding provokes a rapprochement between two successive bridged oxygen atoms thus inducing repulsion between them. Structure of nanotubes leads to modulate the O-O distance from 2.845 Å to 4.541 Å whereas the unique value of the anatase is 3.809 Å. This modulation of the internuclear distance O-O may play a role in the reactivity of TiO2 process involving two neighboring oxygen and can allow the proper choice of the nanotube to be used in catalysis.

  14. Controlled fabrication of porous double-walled TiO2 nanotubes via ultraviolet-assisted anodization.

    PubMed

    Ali, Ghafar; Kim, Hyun Jin; Kim, Jae Joon; Cho, Sung Oh

    2014-04-07

    Double-walled TiO2 nanotubes with porous wall morphologies are fabricated by anodization under ultraviolet (UV) irradiation. TiO2 formed by anodization of Ti is activated to generate electrons and holes by UV and the anodization process is influenced by the photo-generated charges. As a consequence, morphologies of the fabricated TiO2 nanotubes can be adjusted by controlling the UV illumination. Double-walled TiO2 nanotubes or single-walled nanotubes can be selectively formed by switching on/off the UV illumination. The thickness of the inner and outer walls of the double-walled nanotubes can be tailored by changing the UV power. Due to their larger surface areas compared to single-walled nanotubes, the porous double-walled nanotubes exhibit an enhanced photo-degradation rate for methylene blue (MB). The mechanism of the porous double-walled TiO2 nanotubes is proposed based on the photoactive semiconducting property of the as-growing TiO2 nanotubes under UV.

  15. Transparent TiO2 nanotube array photoelectrodes prepared via two-step anodization.

    PubMed

    Kim, Jin Young; Zhu, Kai; Neale, Nathan R; Frank, Arthur J

    2014-01-01

    Two-step anodization of transparent TiO2 nanotube arrays has been demonstrated with aid of a Nb-doped TiO2 buffer layer deposited between the Ti layer and TCO substrate. Enhanced physical adhesion and electrochemical stability provided by the buffer layer has been found to be important for successful implementation of the two-step anodization process. With the proposed approach, the morphology and thickness of NT arrays could be controlled very precisely, which in turn, influenced their optical and photoelectrochemical properties.

  16. Transparent TiO2 nanotube array photoelectrodes prepared via two-step anodization

    DOE PAGES

    Kim, Jin Young; Zhu, Kai; Neale, Nathan R.; ...

    2014-04-04

    Two-step anodization of transparent TiO2 nanotube arrays has been demonstrated with aid of a Nb-doped TiO2 buffer layer deposited between the Ti layer and TCO substrate. Enhanced physical adhesion and electrochemical stability provided by the buffer layer has been found to be important for successful implementation of the two-step anodization process. As a result, with the proposed approach, the morphology and thickness of NT arrays could be controlled very precisely, which in turn, influenced their optical and photoelectrochemical properties.

  17. Photocatalytic Oxidation of Propylene on Pd-Loaded Anatase TiO2 Nanotubes Under Visible Light Irradiation.

    PubMed

    Li, Chen; Zong, Lanlan; Li, Qiuye; Zhang, Jiwei; Yang, Jianjun; Jin, Zhensheng

    2016-12-01

    TiO2 nanotubes attract much attention because of their high photoelectron-chemical and photocatalytic efficiency. But their large band gap leads to a low absorption of the solar light and limits the practical application. How to obtain TiO2 nanotubes without any dopant and possessing visible light response is a big challenge nowadays. Orthorhombic titanic acid nanotubes (TAN) are a special precursor of TiO2, which possess large Brunauer-Emmett-Teller (BET) surface areas and strong ion exchange and adsorption capacity. TAN can transform to a novel TiO2 with a large amount of single-electron-trapped oxygen vacancies (SETOV) during calcination, while their nanotubular structure would be destroyed, and a BET surface area would decrease remarkably. And interestingly, SETOV can lead to a visible light response for this kind of TiO2. Herein, glucose was penetrated into TAN by the vacuum inhalation method, and TAN would dehydrate to anatase TiO2, and glucose would undergo thermolysis completely in the calcination process. As a result, the pure TiO2 nanotubes with visible light response and large BET surface areas were obtained. For further improving the photocatalytic activity, Pd nanoparticles were loaded as the foreign electron traps on TiO2 nanotubes and the photocatalytic oxidation efficiency of propylene was as high as 71 % under visible light irradiation, and the photostability of the catalyst kept over 90 % after 4 cyclic tests.

  18. Photocatalytic Oxidation of Propylene on Pd-Loaded Anatase TiO2 Nanotubes Under Visible Light Irradiation

    NASA Astrophysics Data System (ADS)

    Li, Chen; Zong, Lanlan; Li, Qiuye; Zhang, Jiwei; Yang, Jianjun; Jin, Zhensheng

    2016-05-01

    TiO2 nanotubes attract much attention because of their high photoelectron-chemical and photocatalytic efficiency. But their large band gap leads to a low absorption of the solar light and limits the practical application. How to obtain TiO2 nanotubes without any dopant and possessing visible light response is a big challenge nowadays. Orthorhombic titanic acid nanotubes (TAN) are a special precursor of TiO2, which possess large Brunauer-Emmett-Teller (BET) surface areas and strong ion exchange and adsorption capacity. TAN can transform to a novel TiO2 with a large amount of single-electron-trapped oxygen vacancies (SETOV) during calcination, while their nanotubular structure would be destroyed, and a BET surface area would decrease remarkably. And interestingly, SETOV can lead to a visible light response for this kind of TiO2. Herein, glucose was penetrated into TAN by the vacuum inhalation method, and TAN would dehydrate to anatase TiO2, and glucose would undergo thermolysis completely in the calcination process. As a result, the pure TiO2 nanotubes with visible light response and large BET surface areas were obtained. For further improving the photocatalytic activity, Pd nanoparticles were loaded as the foreign electron traps on TiO2 nanotubes and the photocatalytic oxidation efficiency of propylene was as high as 71 % under visible light irradiation, and the photostability of the catalyst kept over 90 % after 4 cyclic tests.

  19. PAMAM-grafted TiO2 nanotubes as novel versatile materials for drug delivery applications.

    PubMed

    Torres, Cecilia C; Campos, Cristian H; Diáz, Carola; Jiménez, Verónica A; Vidal, Felipe; Guzmán, Leonardo; Alderete, Joel B

    2016-08-01

    PAMAM-grafted TiO2 nanotubes (PAMAM-TiO2NT) have been synthesized and evaluated as new drug nanocarriers, using curcumin (CUR), methotrexate (MTX), and silibinin (SIL) as model therapeutic compounds. TiO2NT were surface-modified using a silane coupling agent and subsequently conjugated with PAMAM dendrimer of the third generation. The characterization of PAMAM-TiO2NT nanomaterials was performed by FTIR, TEM, N2 adsorption-desorption isotherms, XRD, and TGA techniques, which accounted for a 2.6wt.% of PAMAM grafting in the prepared materials. The drug loading capacity, drug release properties, and cytotoxicity of PAMAM-TiO2NT showed a significant improvement compared to pristine TiO2NT, thus revealing the promising properties of these new materials for drug delivery purposes.

  20. Recent progress in all-solid-state quantum dot-sensitized TiO2 nanotube array solar cells

    NASA Astrophysics Data System (ADS)

    Wang, Qingyao; Chen, Chao; Liu, Wei; Gao, Shanmin; Yang, Xiuchun

    2016-01-01

    All-solid-state quantum dot-sensitized TiO2 nanotube array solar cells have been drawing great attention to solar energy conversion, which break through restrictions in traditional solar cells, such as the high recombination at interfaces of porous TiO2 films/sensitizers/hole conductors/counter electrodes, instability of dyes, and leakage of solution electrolyte, and so the novel solar cells exhibit promising applications in the future. In this Minireview article, the assembling of solar cells including the preparation of TiO2 nanotube array photoanodes, quantum dot preparation and sensitization on photoanodes, filling of hole conductors in TiO2 nanotubes, and selection of counter electrodes are overviewed, and the development course of all-solid-state quantum dot-sensitized TiO2 nanotube array solar cells in recent years are summarized in detail. Moreover, the influences of TiO2 nanotube array photoanodes, quantum dots, solid electrolyte, and counter electrodes on photon-to-current efficiencies of solar cells are summarized. In addition, current problems of solid-state quantum dot-sensitized TiO2 nanotube array solar cells are analyzed, and the corresponding improvements, such as multisensitizers and passivation layers, are proposed to improve the photoelectric conversion efficiency. Finally, this Minireview provides a perspective for the future development of this novel solar cell.

  1. Electronic properties of free-standing TiO2 nanotube arrays fabricated by electrochemical anodization.

    PubMed

    Chen, Chi Liang; Dong, Chung-Li; Chen, Chia-Hao; Wu, Jen-Wei; Lu, Ying-Rui; Lin, Chin-Jung; Liou, Sofia Ya Hsuan; Tseng, Chuan-Ming; Kumar, Krishna; Wei, Da-Hua; Guo, Jinghua; Chou, Wu-Ching; Wu, Maw-Kuen

    2015-09-14

    Nanotubular TiO2 has attracted considerable attention owing to its unique functional properties, including high surface area and vectorial charge transport along the nanotube, making it a good photocatalytic material. Anodic TiO2-nanotube (TiNT) arrays on a Ti foil substrate were prepared by electrochemical anodic oxidation and SEM/HRTEM/XRD analyses have suggested that the walls of TiO2 tubes are formed from stacked [101] planes (anatase). Both HRTEM and XRD indicate an interplanar spacing of d101 = 0.36 nm in the wall structure. Despite the large amount of work done on nanotube synthesis, a thorough investigation of the electronic and atomic structures of free-standing TiNT arrays has not yet been carried out. X-ray absorption spectroscopy (XAS), resonant inelastic X-ray scattering (RIXS) and scanning photoelectron microscopy (SPEM) are employed herein to examine the electronic and atomic structures at the top and bottom of TiNT arrays. These analyses demonstrate the presence of mixed valence states of the Ti ions (Ti(3+) and Ti(4+)) and a structural distortion at the bottom cap region of the TiNT. Additionally, the results obtained herein suggest the formation of a defective anatase phase at the bottom cap barrier layer between the Ti foil substrate and TiNT during the growth of electrochemically anodized nanotubes.

  2. Synthesis of self-organized TiO2 nanotube arrays: Microstructural, stereoscopic, and topographic studies

    NASA Astrophysics Data System (ADS)

    Quiroz, Heiddy P.; Dussan, A.

    2016-08-01

    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 (TiO2) 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 TiO2 phases, were observed from the XRD pattern. These phases were corroborated via μXRD measurements, and the Ti3O5 phase was also observed in detail. Absorption coefficient (α), optical band gap (Eg), and extinction coefficient (ɛ) of TiO2 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.

  3. Biofilm formation on a TiO2 nanotube with controlled pore diameter and surface wettability

    NASA Astrophysics Data System (ADS)

    Anitha, V. C.; Lee, Jin-Hyung; Lee, Jintae; Narayan Banerjee, Arghya; Joo, Sang Woo; Min, Bong Ki

    2015-02-01

    Titania (TiO2) nanotube arrays (TNAs) with different pore diameters (140 - 20 nm) are fabricated via anodization using hydrofluoric acid (HF) containing ethylene glycol (EG) by changing the HF-to-EG volume ratio and the anodization voltage. To evaluate the effects of different pore diameters of TiO2 nanotubes on bacterial biofilm formation, Shewanella oneidensis (S. oneidensis) MR-1 cells and a crystal-violet biofilm assay are used. The surface roughness and wettability of the TNA surfaces as a function of pore diameter, measured via the contact angle and AFM techniques, are correlated with the controlled biofilm formation. Biofilm formation increases with the decreasing nanotube pore diameter, and a 20 nm TiO2 nanotube shows the maximum biofilm formation. The measurements revealed that 20 nm surfaces have the least hydrophilicity with the highest surface roughness of ˜17 nm and that they show almost a 90% increase in the effective surface area relative to the 140 nm TNAs, which stimulate the cells more effectively to produce the pili to attach to the surface for more biofilm formation. The results demonstrate that bacterial cell adhesion (and hence, biofilm formation) can effectively be controlled by tuning the roughness and wettability of TNAs via controlling the pore diameters of TNA surfaces. This biofilm formation as a function of the surface properties of TNAs can be a potential candidate for both medical applications and as electrodes in microbial fuel cells.

  4. Novel phosphorus doped carbon nitride modified TiO2 nanotube arrays with improved photoelectrochemical performance

    NASA Astrophysics Data System (ADS)

    Su, Jingyang; Geng, Ping; Li, Xinyong; Zhao, Qidong; Quan, Xie; Chen, Guohua

    2015-10-01

    Novel phosphorus-doped graphitic-carbon nitride (P-C3N4) modified vertically aligned TiO2 nanotube arrays (NTs) were designed and synthesized. They can significantly enhance the conduction and utilization of photogenerated charge carriers of TiO2 NTs. The heterostructure was successfully fabricated through a three-step process: electrochemical anodization and wet-dipping followed by thermal polymerization. The prepared P-C3N4/TiO2 NTs exhibit enhanced light-absorption characteristics and improved charge separation and transfer ability, thus resulting in a 3-fold photocurrent (1.98 mA cm-2 at 0 V vs. Ag/AgCl) compared with that of pure TiO2 NTs (0.66 mA cm-2 at 0 V vs. Ag/AgCl) in 1 M NaOH solution. The prepared P-C3N4/TiO2 NT photoelectrodes also present excellent photocatalytic and photoelectrocatalytic capabilities in the degradation of methylene blue (MB). The kinetic rate of P-C3N4/TiO2 NTs in the photoelectrocatalytic process for MB is 2.7 times that of pristine TiO2 NTs. Furthermore, the prepared sample was used as a photoanode for solar-driven water splitting, giving a H2 evolution rate of 36.6 μmol h-1 cm-2 at 1.0 V vs. RHE under simulated solar light illumination. This novel structure with a rational design for a visible light response shows potential for metal free materials in photoelectrochemical applications.Novel phosphorus-doped graphitic-carbon nitride (P-C3N4) modified vertically aligned TiO2 nanotube arrays (NTs) were designed and synthesized. They can significantly enhance the conduction and utilization of photogenerated charge carriers of TiO2 NTs. The heterostructure was successfully fabricated through a three-step process: electrochemical anodization and wet-dipping followed by thermal polymerization. The prepared P-C3N4/TiO2 NTs exhibit enhanced light-absorption characteristics and improved charge separation and transfer ability, thus resulting in a 3-fold photocurrent (1.98 mA cm-2 at 0 V vs. Ag/AgCl) compared with that of pure TiO2 NTs (0

  5. Analysis of the electron transport properties in dye-sensitized solar cells using highly ordered TiO2 nanotubes and TiO2 nanoparticles.

    PubMed

    Kao, Mu-Jung; Chang, Ho; Cho, Kun-Ching; Kuo, Chin-Guo; Chien, Shu-Hua; Liang, Shi-Sheng

    2012-04-01

    This study uses TiO2 nanoparticles and highly ordered anatase TiO2 nanotubes (AOTnt) as thin film photoanodes for dye-sensitized solar cells (DSSCs). DSSCs are assembled by single-layer and double-layer films of photoanodes and their electron transfer performance is compared. TiO2 nanoparticles were fabricated by the sol-gel method, and AOTnts were grown on titanium foil. This study uses TiO2 nanoparticles or AOTnts to prepare single-layer photoanodes and TiO2 nanoparticles coated on an AOTnt film to fabricate double-layer photoanodes. These three different photoanodes are soaked in dye and assembled into DSSCs, and their open-loop voltage recession, electrochemical impedance, lifetime, life cycle, and effective diffusion coefficient are measured. Electron transfer efficiency of the photoanodes and light harvesting efficiency are further analyzed. The results show that the electron transfer efficiency, open-loop voltage recession, lifetime, life cycle, and effective diffusion coefficient of the DSSCs assembled using double-layer photoanodes (AOTnt-TiO2) are superior to those of single-layer photoanodes (TiO2 or AOTnt).

  6. An efficient photoanode consisting of TiO2 nanoparticle-filled TiO2 nanotube arrays for dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Li, Quantong; Li, Siqian; Wang, Yi; Ye, Cong; Ruterana, Pierre; Wang, Hao

    2014-12-01

    An efficient photoanode consisting of TiO2 nanoparticle-filled TiO2 nanotube (TNT) arrays is prepared by a sol-gel process through hydrolysis and condensation of titaniumtetrachloride in an aqueous medium containing alcohol and ammonia. By introducing the TiO2 nanoparticles of proper particle size ∼20 nm into TNT arrays, the surface area, dye adsorption, short-circuit photocurrent density (Jsc), open circuit voltage (Voc) and the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs) are significantly improved (up to 107% enhancement on PCE). Particularly, the addition of alcohol and ammonia in TiO2 sol results in more hydroxyl groups chemisorbed onto the surface of the photoanodes, which is favorable for achieving large amount of dye adsorption. The influence of sol-treating time on the microstructure, morphology of photoanodes and the corresponding photovoltaic performance of DSSCs are investigated. It is found that immersing the TNT arrays into TiO2 sol for 0.5-2 h gives PCE of DSSC higher than 9.6%, and the highest PCE of 9.86% is achieved in DSSC when treating the TNT arrays with TiO2 sol for 2 h.

  7. Structural feature and catalytic performance of Cu species distributed over TiO2 nanotubes.

    PubMed

    Nian, Jun-Nan; Chen, Shin-An; Tsai, Chien-Cheng; Teng, Hsisheng

    2006-12-28

    Copper oxide was deposited on tubular TiO2 via Cu2+ introduction into a titanate nanotube aggregate followed by calcination. The titanate has a layered structure allowing Cu intercalation and can readily transform into anatase TiO2 via calcination for condensation of the constituting layers. The activity of the tubular catalysts, with a Cu content of 2 wt %, in selective NO reduction with NH3 was compared with those of other 2 wt % Cu/TiO2 catalysts using TiO2 nanoparticles as the support. The Cu species supported on the nanotubes showed a higher activity than those supported on the nanoparticles. X-ray absorption near-edge structure (XANES) analysis showed that the Cu species on all the TiO2 supports are in the +2 state. Extended X-ray absorption fine structure (EXAFS) investigations of these catalysts reflected higher degrees of CuO dispersion and Cu2+ dissolution into the TiO2 lattice for the tubular Cu/TiO2 catalysts. Absence of CuO bulk detection by a temperature-programmed reduction analysis for the tubular catalysts confirmed the high CuO-dispersion feature of the tubular catalysts. The dissolution of Cu2+ to form a CuxTi1-xO2 type of solid solution was improved by using an in-situ ion-intercalation method for Cu deposition on the nanotubes. A fraction as high as 40% for Cu2+ dissolution was obtained for the tubular catalysts while only 20% was obtained for the particulate catalysts. The CuxTi1-xO2 species were considered one form of the active sites on the Cu/TiO2 catalysts.

  8. Influence of Anodization Time and Voltage on the Parameters of TiO2 Nanotubes

    NASA Astrophysics Data System (ADS)

    Chernozem, R. V.; Surmeneva, M. A.; Surmenev, R. A.

    2016-02-01

    A vertically aligned titania nanotube layer was obtained by electrochemical anodic oxidation in the electrolyte contained 0.4 wt% solution of NH4F in 54 ml of ethylene glycol and 5 ml of deionized water, after titanium was chemically cleaned/etched with a mixture of HCl, H2O and HNO3 solution for removing the natural oxide films. The morphology and composition of the titania nanotube layer were examined by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The anodization of TiO2 nanotubes was done using 60 V for 240 min and 30 min, and 30 V for 30 min. The diameter of the titania nanotubes was about 52-156 nm, the wall thickness about 32-53 nm and the height about 0.9-6.3 μm. The pore size of TiO2 nanotubes influences the dissolution rate of CaP thin films and Young's modulus, which is significantly lower than that of the Ti substrate. Our future challenge will be investigation of the microstructure and mechanical behavior of titania nanotubes with CaP film.

  9. Improvement of the bio-functional properties of TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Roguska, A.; Pisarek, M.; Belcarz, A.; Marcon, L.; Holdynski, M.; Andrzejczuk, M.; Janik-Czachor, M.

    2016-12-01

    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 TiO2 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, TiO2 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.

  10. Two novel hierarchical homogeneous nanoarchitectures of TiO2 nanorods branched and P25-coated TiO2 nanotube arrays and their photocurrent performances

    PubMed Central

    2011-01-01

    We report here for the first time the synthesis of two novel hierarchical homogeneous nanoarchitectures of TiO2 nanorods branched TiO2 nanotube arrays (BTs) and P25-coated TiO2 nanotube arrays (PCTs) using two-step method including electrochemical anodization and hydrothermal modification process. Then the photocurrent densities versus applied potentials of BTs, PCTs, and pure TiO2 nanotube arrays (TNTAs) were investigated as well. Interestingly, at -0.11 V and under the same illumination condition, the photocurrent densities of BTs and PCTs show more than 1.5 and 1 times higher than that of pure TNTAs, respectively, which can be mainly attributed to significant improvement of the light-absorbing and charge-harvesting efficiency resulting from both larger and rougher surface areas of BTs and PCTs. Furthermore, these dramatic improvements suggest that BTs and PCTs will achieve better photoelectric conversion efficiency and become the promising candidates for applications in DSSCs, sensors, and photocatalysis. PMID:21711607

  11. Aggregated TiO2 Based Nanotubes for Dye Sensitized Solar Cells

    SciTech Connect

    Nie, Zimin; Zhou, Xiaoyuan; Zhang, Qifeng; Cao, Guozhong; Liu, Jun

    2013-11-01

    One-dimensional (1D) semiconducting oxides have attracted great attention for dye sensitized solar cells (DSCs), but the overall performance is still quite limited as compared to TiO2 nanocrystalline DSCs. Here, we report the synthesis of aggregated TiO2 based nanotubes with controlled morphologies and crystalline structures to obtain an overall power conversion efficiency of 9.9% using conventional dye without any additional chemical treatment steps. The high efficiency is attributed to the unique aggregate structure for light harvesting, optimized high surface area, and good crystallinity of the nanotube aggregates obtained through proper thermal annealing. This study demonstrates that high efficiency DSCs can be obtained with 1D nanomaterials, and provides lessons on the importance of optimizing both the nanocrystalline structure and the overall microscale morphology.

  12. Wire-shaped perovskite solar cell based on TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoyan; Kulkarni, Sneha A.; Li, Zhen; Xu, Wenjing; Batabyal, Sudip K.; Zhang, Sam; Cao, Anyuan; Wong, Lydia Helena

    2016-05-01

    In this work, a wire-shaped perovskite solar cell based on TiO2 nanotube (TNT) arrays is demonstrated for the first time by integrating a perovskite absorber on TNT-coated Ti wire. Anodization was adopted for the conformal growth of TNTs on Ti wire, together with the simultaneous formation of a compact TiO2 layer. A sequential step dipping process is employed to produce a uniform and compact perovskite layer on top of TNTs with conformal coverage as the efficient light absorber. Transparent carbon nanotube film is wrapped around Ti wire as the hole collector and counter electrode. The integrated perovskite solar cell wire by facile fabrication approaches shows a promising future in portable and wearable textile electronics.

  13. Wire-shaped perovskite solar cell based on TiO2 nanotubes.

    PubMed

    Wang, Xiaoyan; Kulkarni, Sneha A; Li, Zhen; Xu, Wenjing; Batabyal, Sudip K; Zhang, Sam; Cao, Anyuan; Wong, Lydia Helena

    2016-05-20

    In this work, a wire-shaped perovskite solar cell based on TiO2 nanotube (TNT) arrays is demonstrated for the first time by integrating a perovskite absorber on TNT-coated Ti wire. Anodization was adopted for the conformal growth of TNTs on Ti wire, together with the simultaneous formation of a compact TiO2 layer. A sequential step dipping process is employed to produce a uniform and compact perovskite layer on top of TNTs with conformal coverage as the efficient light absorber. Transparent carbon nanotube film is wrapped around Ti wire as the hole collector and counter electrode. The integrated perovskite solar cell wire by facile fabrication approaches shows a promising future in portable and wearable textile electronics.

  14. Photoelectrocatalytic oxidation of aqueous ammonia using TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Wang, Hua; Zhang, Xiufang; Su, Yan; Yu, Hongtao; Chen, Shuo; Quan, Xie; Yang, Fenglin

    2014-08-01

    The photoelectrocatalytic removal of ammonia in water was investigated using highly ordered TiO2 nanotube arrays as a photoanode. The results showed that the removal efficiency of total ammonia nitrogen (TAN) was closely related to the bias potential applied on TiO2 nanotube photoanode. Even without an adjustment of pH, over 99% of TAN (initial concentration 0.145 mM) was removed in 120 min with a bias potential of 1.0 V. It is important to note that the TAN could be directly oxidized into N2 and NO3--N without accumulation of an intermediate product of NO2--N. Meanwhile, the presence of the chemical scavengers revealed that photogenerated holes were the main oxidative species for the TAN oxidation. This work highlights the potential application of photoelectrocatalysis in the field of aqueous ammonia elimination.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    Semitransparent composite films of Au loaded TiO2 nanotubes (TNT-Au) were prepared by sputtering Au nanoparticles on highly transparent TiO2 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.

  16. Structure reconstruction of TiO2-based multi-wall nanotubes: first-principles calculations.

    PubMed

    Bandura, A V; Evarestov, R A; Lukyanov, S I

    2014-07-28

    A new method of theoretical modelling of polyhedral single-walled nanotubes based on the consolidation of walls in the rolled-up multi-walled nanotubes is proposed. Molecular mechanics and ab initio quantum mechanics methods are applied to investigate the merging of walls in nanotubes constructed from the different phases of titania. The combination of two methods allows us to simulate the structures which are difficult to find only by ab initio calculations. For nanotube folding we have used (1) the 3-plane fluorite TiO2 layer; (2) the anatase (101) 6-plane layer; (3) the rutile (110) 6-plane layer; and (4) the 6-plane layer with lepidocrocite morphology. The symmetry of the resulting single-walled nanotubes is significantly lower than the symmetry of initial coaxial cylindrical double- or triple-walled nanotubes. These merged nanotubes acquire higher stability in comparison with the initial multi-walled nanotubes. The wall thickness of the merged nanotubes exceeds 1 nm and approaches the corresponding parameter of the experimental patterns. The present investigation demonstrates that the merged nanotubes can integrate the two different crystalline phases in one and the same wall structure.

  17. A Pt-doped TiO2 nanotube arrays sensor for detecting SF6 decomposition products.

    PubMed

    Zhang, Xiaoxing; Tie, Jing; Zhang, Jinbin

    2013-10-30

    The detection of partial discharge and analysis of SF6 gas components in gas-insulated switchgear (GIS) is important for the diagnosis and operating state assessment of power equipment. The use of a Pt-doped TiO2 nanotube arrays sensor for detecting sulfur hexafluoride (SF6) decomposition products is proposed in this paper. The electrochemical pulse deposition method is employed to prepare the sensor array. The sensor's response to the main characteristic gaseous decomposition products of SF6 is evaluated. The gas sensing characteristic curves of the Pt-doped TiO2 nanotube sensor and intrinsic TiO2 nanotube arrays sensor are compared. The mechanism of the sensitive response is discussed. Test results showed that the Pt-doped nanoparticles not only change the gas sensing selectivity of the TiO2 nanotube arrays sensor with respect to the main characteristic SF6 decomposition products, but also reduce the operating temperature of the sensor.

  18. The effect of multiwalled carbon nanotube doping on the CO gas sensitivity of TiO2 xerogel composite film

    NASA Astrophysics Data System (ADS)

    Lee, Jin-Seok; Ha, Tae-Jung; Hong, Min-Hee; Park, Chang-Sun; Park, Hyung-Ho

    2013-03-01

    A simple sol-gel method was applied for the synthesis of 0.01 wt% multiwalled carbon nanotubes (MWCNTs)-doped TiO2 xerogel composite film. The film's CO gas sensing properties were then evaluated. Doped MWCNTs were coated with TiO2 and distributed on a TiO2 xerogel matrix. The TiO2 xerogel showed an anatase structure after heat treatment at 450 °C under vacuum. The specific surface area of the composite material was larger than the pure TiO2 xerogel material. The CO gas sensitivity of the MWCNTs(0.01 wt%)-doped TiO2 xerogel composite film was found to be seven times higher than that of pure TiO2 xerogel film and to have good stability. This higher gas-sensing property of the composite film was due to both an increase of specific surface area and the n-p junction structure of the TiO2 xerogel coated on MWCNTs. The electrons generated from TiO2 after adsorption of CO gas induces electron transfer from the TiO2 to the MWCNTs. This induces a characteristic change in the MWCNTs from p-type to n-type, and the resistance of MWCNTs-doped TiO2 xerogel composite sensor is therefore decreased.

  19. Ni-doped TiO2 nanotubes for wide-range hydrogen sensing

    PubMed Central

    2014-01-01

    Doping of titania nanotubes is one of the efficient way to obtain improved physical and chemical properties. Through electrochemical anodization and annealing treatment, Ni-doped TiO2 nanotube arrays were fabricated and their hydrogen sensing performance was investigated. The nanotube sensor demonstrated a good sensitivity for wide-range detection of both dilute and high-concentration hydrogen atmospheres ranging from 50 ppm to 2% H2. A temperature-dependent sensing from 25°C to 200°C was also found. Based on the experimental measurements and first-principles calculations, the electronic structure and hydrogen sensing properties of the Ni-doped TiO2 with an anatase structure were also investigated. It reveals that Ni substitution of the Ti sites could induce significant inversion of the conductivity type and effective reduction of the bandgap of anatase oxide. The calculations also reveal that the resistance change for Ni-doped anatase TiO2 with/without hydrogen absorption was closely related to the bandgap especially the Ni-induced impurity level. PMID:24624981

  20. Formation process of TiO2 nanotube arrays prepared by anodic oxidation method.

    PubMed

    Li, Hongyi; Liu, Man; Wang, Hong; Wu, Junshu; Su, Penglei; Li, Dasheng; Wang, Jinshu

    2013-06-01

    TiO2 nanotube array thin films have great potential in many fields, such as solar cell, photo catalyst, photo-induced cathodic protection for metals and bioactivity. In order to investigate the formation process of the TiO2 nanotube array thin films, the EIS spectrum and current density were measured during the anodic oxidation. The results showed that the formation process could be divided into four stages. The current density decreased sharply at the first stage, and then increased at the second stage, followed by declining and finally remained constant value. In addition, the current density increased with the anodic voltage. The EIS spectrum varied in different stage. The simulated circuit was composed three sections, the first sections indicated the resistance of the electrolyte, the second one gave the double layer structure between the electrolyte and titanium electrode, the third one was a inductive loop, which represented the anions absorbed on the surface of the TiO2 nanotube's wall. The more cations were absorbed, the higher value of the inductive loop would be. The EIS results showed that the value increased with the outer voltage, which means that more cations were absorbed under the higher anodic voltage.

  1. Electrical characterization of TiO2 nanotubes synthesized through electrochemical anodizing method

    NASA Astrophysics Data System (ADS)

    Manescu Paltanea, Veronica; Paltanea, Gheorghe; Popovici, Dorina; Jiga, Gabriel

    2016-05-01

    In the present paper, the electrochemical anodizing method was used for the obtaining of TiO2 nanotube layers, developed on titanium surface. Self-organized titanium nanotubes were obtained when an aqueous solution of 49.5 wt % H2O - 49.5 wt % glycerol - 1 wt % HF was used as electrolyte, the anodizing time being equal to 8 hours and the applied voltage to 25 V. Scanning electron microscopy shows that the one-dimensional nanostructure has a tubular configuration with an inner diameter of approximately 60 nm and an outer diameter of approximately 100 nm. The electrical properties of these materials were analyzed through dielectric spectroscopy method.

  2. Integration of TiO2 nanotube arrays into solid-state dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Bandara, J.; Shankar, K.; Basham, J.; Wietasch, H.; Paulose, M.; Varghese, O. K.; Grimes, C. A.; Thelakkat, M.

    2011-02-01

    In this investigation, transparent TiO2 nanotube arrays prepared on a FTO substrate are employed as 1D nanostructures providing elongated direct pathways for electron transport and collection in solid-state dye-sensitized solar cell (SDSC). Donor-antenna (D-A) dyes provide an exciting route for improving the light harvesting efficiency in dye sensitized solar cells owing to their high molar extinction coefficients and the effective spatial separation of charges in the charge-separated state. Hence in this study we fabricated SDSC devices with different thicknesses of transparent TiO2 nanotube array electrodes sensitized with Ru-(II)-donor-antenna dye and spiro-OMeTAD as a hole conductor. At AM 1.5 G, 100 mW/cm2 illumination intensity, a power conversion efficiency of 1.94% was achieved when the TiO2 nanotubes are initially subjected to TiCl4 treatment. Furthermore, a linear increase in the cell current without loss in fill factor is observed for increasing length of TiO2 nanotubes. The structural and morphological characteristics of the transparent TiO2 nanotube arrays as well as the optimal conditions for the fabrication of SDSCs with transparent TiO2 nanotubes on FTO glass are reported.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

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

    2017-12-01

    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.

  5. Mechanical degradation of TiO2 nanotubes with and without nanoparticulate silver coating.

    PubMed

    Shivaram, Anish; Bose, Susmita; Bandyopadhyay, Amit

    2016-06-01

    The primary objective of this research was to evaluate the extent of mechanical degradation on TiO2 nanotubes on Ti with and without nano-particulate silver coating using two different lengths of TiO2 nanotubes-300nm and ~1µm, which were fabricated on commercially pure Titanium (cp-Ti) rods using anodization method using two different electrolytic mediums-(1) deionized (DI) water with 1% HF, and (2) ethylene glycol with 1% HF, 0.5wt% NH4F and 10% DI water. Nanotubes fabricated rods were implanted into equine cadaver bone to evaluate mechanical damage at the surface. Silver was electrochemically deposited on these nanotubes and using a release study, silver ion concentrations were measured before and after implantation, followed by surface characterization using a Field Emission Scanning Electron Microscope (FESEM). In vitro cell-material interaction study was performed using human fetal osteoblast cells (hFOB) to understand the effect of silver coating using an MTT assay for proliferation and to determine any cytotoxic effect on the cells and to study its biocompatibility. No significant damage due to implantation was observed for nanotubes up to ~1µm length under current experimental conditions. Cell-materials interaction showed no cytotoxic effects on the cells due to silver coating and anodization of samples.

  6. Gold nanoparticles-immobilized, hierarchically ordered, porous TiO2 nanotubes for biosensing of glutathione

    PubMed Central

    Mers, SV Sheen; Kumar, Elumalai Thambuswamy Deva; Ganesh, V

    2015-01-01

    Glutathione (GSH) is vital for several functions of our human body such as neutralization of free radicals and reactive oxygen compounds, maintaining the active forms of vitamin C and E, regulation of nitric oxide cycle, iron metabolism, etc. It is also an endogenous antioxidant in most of the biological reactions. Given the importance of GSH, a simple strategy is proposed in this work to develop a biosensor for quantitative detection of GSH. This particular biosensor comprises of gold nanoparticles (Au NPs)-immobilized, hierarchically ordered titanium dioxide (TiO2) porous nanotubes. Hexagonally arranged, honeycomb-like nanoporous tubular TiO2 electrodes are prepared by using a simple electrochemical anodization process by applying a constant potential of 30 V for 24 hours using ethylene glycol consisting of ammonium fluoride as an electrolytic medium. Structural morphology and crystalline nature of such TiO2 nanotubes are analyzed using field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). Interestingly, nanocomposites of TiO2 with Au NPs is prepared in an effort to alter the intrinsic properties of TiO2, especially tuning of its band gap. Au NPs are prepared by a well-known Brust and Schiffrin method and are immobilized onto TiO2 electrodes which act as a perfect electrochemical sensing platform for GSH detection. Structural characterization and analysis of these modified electrodes are performed using FESEM, XRD, and UV-visible spectroscopic studies. GSH binding events on Au NPs-immobilized porous TiO2 electrodes are monitored by electrochemical techniques, namely, cyclic voltammetry (CV) and chronoamperometry (CA). Several parameters such as sensitivity, selectivity, stability, limit of detection, etc are investigated. In addition, Au NPs dispersed in aqueous medium are also explored for naked-eye detection of GSH using UV-visible spectroscopy in order to compare the performance of the proposed sensor. Our studies clearly indicate

  7. Inverted organic photovoltaic cells using three-dimensionally interconnected TiO2 nanotube arrays.

    PubMed

    Kim, Sehwan; Koh, Joo Hwan; Kim, Jong Hak; Kim, Eunkyoung

    2013-04-01

    Here we describe a simple sol-gel method to fabricate inverted organic photovoltaics (OPV) using interconnected TiO2 nanotubes (inter-TiO2 NT) as an efficient electron transport layer. Three-dimensionally inter-TiO2 NT arrays were prepared by spin-coating a TiO2 precursor solution on the ZnO nanorod (NR) template grown via the liquid phase deposition method. Upon etching of ZnO NRs, inter-TiO2 NT arrays were generated, as confirmed by X-ray diffraction (XRD), energy-filtering transmission electron microscopy (EF-TEM) and field-emission scanning electron microscopy (FE-SEM). A blend of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) deeply infiltrated into the pores of inter-TiO2 NT, as revealed by FE-SEM and atomic force microscopy (AFM) images. The power conversion efficiency (PCE) of inter-TiO2 NT-based inverted OPV reached 3.0% at an air mass of 1.5 (100 mW/cm2), which is a 25% performance improvement compared to flat TiO2 films derived from the sol-gel process or commercial paste. The efficiency improvement arises from facilitated charge separation and collection due to the increased TiO2 interface arera and efficient transport pathway.

  8. Memristive behaviour in poly-acrylic acid coated TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Conti, Daniele; Lamberti, Andrea; Porro, Samuele; Rivolo, Paola; Chiolerio, Alessandro; Fabrizio Pirri, Candido; Ricciardi, Carlo

    2016-12-01

    This work investigates titanium dioxide nanotube arrays (TiO2-NTA) grown by anodic oxidation as an active material for memristive applications. In particular, metal-insulator-metal structures made of vertically oriented amorphous TiO2-NTA grown on titanium foil were exploited in Ti/TiO2-NTA/Pt devices. The deposition of a polymeric thin film between NTA and top electrodes significantly improved the stability of the devices and increased by more than double the off/on resistance ratio. The resistive switching of TiO2-NTA samples crystallised by thermal annealing was also studied. Such devices displayed nonlinear I-V curves characterised by a smooth rectifying behaviour, without any evident resistive switching (RS). Also in this case, the interposition of the polymeric layer enhanced the RS behaviour of TiO2-NTA samples, remarkably increasing the devices’ off/on ratio and endurance. The rise of high resistance states can be simply related to the addition of the polymer as resistance in series, while the variation of the low resistance states is here attributed to the occurrence of surface chemical reactions between polymer functional groups and the metal oxide, which increase the charge carriers available for conduction.

  9. In vivo evaluation of anodic TiO2 nanotubes: an experimental study in the pig.

    PubMed

    von Wilmowsky, Cornelius; Bauer, Sebastian; Lutz, Rainer; Meisel, Mark; Neukam, Friedrich Wilhelm; Toyoshima, Takeshi; Schmuki, Patrik; Nkenke, Emeka; Schlegel, Karl Andreas

    2009-04-01

    Because of their ability to mimic the dimensions of constituent components of natural bone and the possibility to serve as a gene and drug-delivery carrier, nanotubes seem to be a promising coating for medical implants. Aim of this study was to investigate the effects of a TiO(2) nanotube structured surface on periimplant bone formation in vivo when compared with an untreated standard titanium surface. Twenty-five titanium implants covered with an ordered TiO(2) nanotube layer with an individual tube diameter of 30 nm and 25 commercially pure titanium (cp-Ti) implants were placed in the frontal skull of 25 domestic pigs. To evaluate the effects of the nanotube structured implants on the periimplant bone formation, bone-implant contact (BIC), and immunohistochemistry analysis were performed at day 3, 7, 14, 30, and 90. Evaluating immunohistochemistry, a significantly higher collagen type- I expression occurred at day 7 (p = 0.003), day 14 (p = 0.016), and day 30 (p = 0.044), for the nanostructured implants in comparison with the control group. It could be found that a nanotube structured implant surface with a diameter of 30 nm does influence bone formation and bone development by enhancing osteoblast function. SEM evaluation of the specimen surfaces revealed that the nanotube coatings do resist shearing forces that evoked by implant insertion. Because of their simple, low cost, flexible manufacturing and the possibility for the usage as drug or growth factor delivery system, nanotubes seem to be a promising method for future medical implant coatings.

  10. Fabrication and characterization of CdS doped TiO2 nanotube composite and its photocatalytic activity for the degradation of methyl orange.

    PubMed

    Chung, Jinwook; Kim, Seu-Run; Kim, Jong-Oh

    2015-01-01

    CdS doped TiO2 nanotube composite was fabricated by chemical bath deposition, and was characterized by the structural, spectral and photoelectrochemical properties. The results of the structural and spectral properties showed that CdS particles were successfully deposited onto the surface of TiO2 nanotube. It is demonstrated that CdS doped TiO2 nanotube composite improved the light harvesting ability. Power conversion efficiency of about 0.32% was observed. This value is about 2.9 times higher than that of pure TiO2 nanotube. The CdS doped TiO2 nanotube composite possesses relatively higher photocatalytic activity and photodegradation efficiency than that of pure TiO2 nanotube under UV light irradiation, and the degradation efficiency of methyl orange was about 42% at UV intensity of 32 W.

  11. Electrochemical assisted photocatalytic degradation of salicylic acid with highly ordered TiO2 nanotube electrodes

    NASA Astrophysics Data System (ADS)

    Zhang, Qian; Zhu, Jinwei; Wang, Ying; Feng, Jiangtao; Yan, Wei; Xu, Hao

    2014-07-01

    To explore the kinetics of photoelectrocatalytic degradation of salicylic acid, one of the important PPCPs, highly ordered TiO2 nanotube arrays (NTs) were prepared by the electrochemical anodization and characterized with scanning electron microscopy and X-ray diffraction techniques. The effect of TiO2 NTs properties, bias potential, initial salicylic acid concentration and solution pH on the degradation efficiency was studied and carefully analyzed. The results revealed that the salicylic acid degradation follows quasi-first order kinetics in the photoelectrocatalytic process, and the fastest decay kinetics was achieved in acidic environment (pH 2). The result was further interpreted through the electrochemical impedance spectroscopy. It is confirmed that the electrochemical assisted photocatalysis is a synergetic approach to combat stable organic substances with improved efficiency.

  12. Dye-sensitized TiO2 nanotube solar cells: fabrication and electronic characterization.

    PubMed

    Ohsaki, Yoshinori; Masaki, Naruhiko; Kitamura, Takayuki; Wada, Yuji; Okamoto, Takumi; Sekino, Toru; Niihara, Kohichi; Yanagida, Shozo

    2005-12-21

    TiO2 nanotubes (TNTs) with large aspect ratio and large specific surface area were prepared from P25 (Nippon Aerosil) and applied to dye-sensitized titanium dioxide solar cells (DSSCs). Optimization of fabrication conditions, i.e., pH of the starting paste, sintering temperature for the TiO2 electrodes, electrolyte compositions of DSSCs gave the high conversion efficiency with improved open circuit voltage (V(oc)) and fill factor (FF) when compared to DSSCs made of P25. The evaluation of dye adsorption and the photo-injected electron transport such as electron diffusion coefficient (D) and electron lifetime (tau) in TNTs electrodes revealed that the higher efficiency resulted from increase of electron density with keeping much longer tau in TNTs electrodes than in P25 electrodes.

  13. TiO2-Coated Carbon Nanotube-Silicon Solar Cells with Efficiency of 15%

    PubMed Central

    Shi, Enzheng; Zhang, Luhui; Li, Zhen; Li, Peixu; Shang, Yuanyuan; Jia, Yi; Wei, Jinquan; Wang, Kunlin; Zhu, Hongwei; Wu, Dehai; Zhang, Sen; Cao, Anyuan

    2012-01-01

    Combining carbon nanotubes (CNTs), graphene or conducting polymers with conventional silicon wafers leads to promising solar cell architectures with rapidly improved power conversion efficiency until recently. Here, we report CNT-Si junction solar cells with efficiencies reaching 15% by coating a TiO2 antireflection layer and doping CNTs with oxidative chemicals, under air mass (AM 1.5) illumination at a calibrated intensity of 100 mW/cm2 and an active device area of 15 mm2. The TiO2 layer significantly inhibits light reflectance from the Si surface, resulting in much enhanced short-circuit current (by 30%) and external quantum efficiency. Our method is simple, well-controlled, and very effective in boosting the performance of CNT-Si solar cells. PMID:23181192

  14. Photoelectrocatalytic degradation Rhodamine B over highly ordered TiO2 nanotube arrays photoelectrode

    NASA Astrophysics Data System (ADS)

    Wu, Jia; Xu, Hao; Yan, Wei

    2016-11-01

    Different nanotube length of TiO2 nanotube arrays (NTAs) electrodes was successfully prepared by anodization method with different duration time. The as-prepared electrodes were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Mott-Shottky measurement. The influence of bias potential, illumination and nanotube length on Rhodamine B (RhB) degradation was investigated. The results show that applied bias potential and short nanotube length are beneficial to RhB degradation due to the enhanced charge transfer. Moreover, it is found that an induction period exists in the RhB photoelectrodegradation with short nanotube length and the rate is sensitive to the carriers' concentration. This can be attributed to the increased effective holes for degradation RhB and the decreased recombination rate of electrons-holes. Nevertheless, RhB photoelectrodegradation with long nanotube length did not display the similar kinetic characteristic. The possible explanation is that long nanotube length increases the recombination rate of electrons-holes and limits the charge transfer, hence decreases the amount of effectively charge carriers. This may decrease the degradation rate and thus result in the disappearing of the second degradation constant. Moreover, we further demonstrate our deduction by the electrochemical impedance spectroscopy (EIS) and Mott-Shottky measurement.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

  17. Diameter-sensitive biocompatibility of anodic TiO2 nanotubes treated with supercritical CO2 fluid

    PubMed Central

    2013-01-01

    This work reports on the diameter-sensitive biocompatibility of anodic TiO2 nanotubes with different nanotube diameters grown by a self-ordering process and subsequently treated with supercritical CO2 (ScCO2) fluid. We find that highly hydrophilic as-grown TiO2 nanotubes become hydrophobic after the ScCO2 treatment but can effectively recover their surface wettability under UV light irradiation as a result of photo-oxidation of C-H functional groups formed on the nanotube surface. It is demonstrated that human fibroblast cells show more obvious diameter-specific behavior on the ScCO2-treated TiO2 nanotubes than on the as-grown ones in the range of diameters of 15 to 100 nm. This result can be attributed to the removal of disordered Ti(OH)4 precipitates from the nanotube surface by the ScCO2 fluid, thus resulting in purer nanotube topography and stronger diameter dependence of cell activity. Furthermore, for the smallest diameter of 15 nm, ScCO2-treated TiO2 nanotubes reveal higher biocompatibility than the as-grown sample. PMID:23547743

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

    PubMed

    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.

  19. N incorporation and electronic structure in N-doped TiO2(110) rutile

    SciTech Connect

    Cheung, Sau H.; Nachimuthu, Ponnusamy; Joly, Alan G.; Engelhard, Mark H.; Bowman, Michael K.; Chambers, Scott A.

    2007-02-08

    Epitaxial TiO2-xNx film growth under anion-rich conditions is characterized by nearly balanced incorporation rates for substitutional N (NO) and interstitial Ti (Tii). Tii donors fully compensate and stabilize N3-, but preclude the formation of p-type material. Hybridization occurs between Tii(IV) and NO3-, but the value of x is limited to ~0.02 under these conditions. Tii(IV)-NO3- states occur above the valence band maximum of pure TiO2, riving rise to enhanced optical absorption in the visible up to ~2.5 eV. Much higher NO and Tii concentrations result from using cation-rich conditions.

  20. Improved rhBMP-2 function on MBG incorporated TiO2 nanorod films.

    PubMed

    Ge, Fei; Yu, Mengfei; Yu, Cuixia; Lin, Jun; Weng, Wenjian; Cheng, Kui; Wang, Huiming

    2017-02-01

    In the process of biomaterials mediated bone regeneration, rhBMP-2 delivery at efficient dose in sustained kinetics is crucial for promoting cell osteogenic differentiation. Meanwhile, surface morphology of the biomaterials could regulate cellular responses as well as strengthen the rhBMP-2 interaction with cells for better bone induction. Herein, TiO2 nanorod films with varied mesoporous bioactive glass (MBG) incorporation amount were designed to strengthen the efficacy of rhBMP-2, basing on optimized loading/release behaviors and surface nanostructure cooperatively. The MBG incorporation improved rhBMP-2 loading amount and regulated its release behavior. Consequently, the osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) on the incorporated films was extremely enhanced, and the incorporated nanorod film with 200nm MBG thickness exhibited the best osteoinduction effect. However, MBG film and the incorporated nanorod film had the same loading amount of rhBMP-2, the latter showed a much higher expression of 7-day osteogenic differentiation index than the former, which could be attributed to the synergistic effect of optimized rhBMP-2 release behavior and surface morphology. The MBG incorporated TiO2 nanorod films here presents a promising strategy for enhancing osteoinduction through optimized rhBMP-2 release behavior.

  1. Atomic Layer Deposition for Coating of High Aspect Ratio TiO2 Nanotube Layers

    PubMed Central

    2016-01-01

    We present an optimized approach for the deposition of Al2O3 (as a model secondary material) coating into high aspect ratio (≈180) anodic TiO2 nanotube layers using the atomic layer deposition (ALD) process. In order to study the influence of the diffusion of the Al2O3 precursors on the resulting coating thickness, ALD processes with different exposure times (i.e., 0.5, 2, 5, and 10 s) of the trimethylaluminum (TMA) precursor were performed. Uniform coating of the nanotube interiors was achieved with longer exposure times (5 and 10 s), as verified by detailed scanning electron microscopy analysis. Quartz crystal microbalance measurements were used to monitor the deposition process and its particular features due to the tube diameter gradient. Finally, theoretical calculations were performed to calculate the minimum precursor exposure time to attain uniform coating. Theoretical values on the diffusion regime matched with the experimental results and helped to obtain valuable information for further optimization of ALD coating processes. The presented approach provides a straightforward solution toward the development of many novel devices, based on a high surface area interface between TiO2 nanotubes and a secondary material (such as Al2O3). PMID:27643411

  2. Plasma assisted deposition of single and multistacked TiO2 hierarchical nanotube photoanodes.

    PubMed

    Nicolas Filippin, A; Sanchez-Valencia, Juan R; Idígoras, Jesús; Rojas, T Cristina; Barranco, Angel; Anta, Juan A; Borras, Ana

    2017-04-13

    We present herein an evolved methodology for the growth of nanocrystalline hierarchical nanotubes combining physical vapor deposition of organic nanowires (ONWs) and plasma enhanced chemical vacuum deposition of anatase TiO2 layers. The ONWs act as vacuum removable 1D and 3D templates, with the whole process occurring at temperatures ranging from RT to 250 °C. As a result, a high density of hierarchical nanotubes with tunable diameter, length and tailored wall microstructures are formed on a variety of processable substrates as metal and metal oxide films or nanoparticles including transparent conductive oxides. The reiteration of the process leads to the development of an unprecedented 3D nanoarchitecture formed by stacking the layers of hierarchical TiO2 nanotubes. As a proof of concept, we present the superior performance of the 3D nanoarchitecture as a photoanode within an excitonic solar cell with efficiencies as high as 4.69% for a nominal thickness of the anatase layer below 2.75 μm. Mechanical stability and straightforward implementation in devices are demonstrated at the same time. The process is extendable to other functional oxides fabricated by plasma-assisted methods with readily available applications in energy harvesting and storage, catalysis and nanosensing.

  3. Atomic Layer Deposition for Coating of High Aspect Ratio TiO2 Nanotube Layers.

    PubMed

    Zazpe, Raul; Knaut, Martin; Sopha, Hanna; Hromadko, Ludek; Albert, Matthias; Prikryl, Jan; Gärtnerová, V; Bartha, Johann W; Macak, Jan M

    2016-10-05

    We present an optimized approach for the deposition of Al2O3 (as a model secondary material) coating into high aspect ratio (≈180) anodic TiO2 nanotube layers using the atomic layer deposition (ALD) process. In order to study the influence of the diffusion of the Al2O3 precursors on the resulting coating thickness, ALD processes with different exposure times (i.e., 0.5, 2, 5, and 10 s) of the trimethylaluminum (TMA) precursor were performed. Uniform coating of the nanotube interiors was achieved with longer exposure times (5 and 10 s), as verified by detailed scanning electron microscopy analysis. Quartz crystal microbalance measurements were used to monitor the deposition process and its particular features due to the tube diameter gradient. Finally, theoretical calculations were performed to calculate the minimum precursor exposure time to attain uniform coating. Theoretical values on the diffusion regime matched with the experimental results and helped to obtain valuable information for further optimization of ALD coating processes. The presented approach provides a straightforward solution toward the development of many novel devices, based on a high surface area interface between TiO2 nanotubes and a secondary material (such as Al2O3).

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

    PubMed

    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.

  5. Phosphorus Cation Doping: A New Strategy for Boosting Photoelectrochemical Performance on TiO2 Nanotube Photonic Crystals.

    PubMed

    Li, Zhenzhen; Xin, Yanmei; Wu, Wenlong; Fu, Baihe; Zhang, Zhonghai

    2016-11-16

    Photoelectrochemical (PEC) water splitting is a promising technique for sustainable hydrogen generation. However, PEC performance on current semiconductors needs further improvement. Herein, a phosphorus cation doping strategy is proposed to fundamentally boost PEC performance on TiO2 nanotube photonic crystal (TiO2 NTPC) photoelectrodes in both the visible-light region and full solar-light illumination. The self-supported P-TiO2 NTPC photoelectrodes are fabricated by a facile two-step electrochemical anodization method and subsequent phosphidation treatment. The Ti(4+) is partially replaced by P cations (P(5+)) from the crystal lattice, which narrows the band gap of TiO2 and induces charge imbalance by the formation of Ti-O-P bonds. We believe the combination of unique photonic nanostructures of TiO2 NTPCs and P cation doping strategy will open up a new opportunity for enhancing PEC performance of TiO2-based photoelectrodes.

  6. BiVO4/TiO2(N2) Nanotubes Heterojunction Photoanode for Highly Efficient Photoelectrocatalytic Applications

    NASA Astrophysics Data System (ADS)

    Wang, Rui; Bai, Jing; Li, Yunpo; Zeng, Qingyi; Li, Jinhua; Zhou, Baoxue

    2017-04-01

    We report the development of a novel visible response BiVO4/TiO2(N2) nanotubes photoanode for photoelectrocatalytic applications. The nitrogen-treated TiO2 nanotube shows a high carrier concentration rate, thus resulting in a high efficient charge transportation and low electron-hole recombination in the TiO2-BiVO4. Therefore, the BiVO4/TiO2(N2) NTs photoanode enabled with a significantly enhanced photocurrent of 2.73 mA cm-2 (at 1 V vs. Ag/AgCl) and a degradation efficiency in the oxidation of dyes under visible light. Field emission scanning electron microscopy, X-ray diffractometry, energy-dispersive X-ray spectrometer, and UV-Vis absorption spectrum were conducted to characterize the photoanode and demonstrated the presence of both metal oxides as a junction composite.

  7. Fast Growth of Highly Ordered TiO2 Nanotube Arrays on Si Substrate under High-Field Anodization

    NASA Astrophysics Data System (ADS)

    Song, Jingnan; Zheng, Maojun; Zhang, Bin; Li, Qiang; Wang, Faze; Ma, Liguo; Li, Yanbo; Zhu, Changqing; Ma, Li; Shen, Wenzhong

    2017-04-01

    Highly ordered TiO2 nanotube arrays (NTAs) on Si substrate possess broad applications due to its high surface-to-volume ratio and novel functionalities, however, there are still some challenges on facile synthesis. Here, we report a simple and cost-effective high-field (90-180 V) anodization method to grow highly ordered TiO2 NTAs on Si substrate, and investigate the effect of anodization time, voltage, and fluoride content on the formation of TiO2 NTAs. The current density-time curves, recorded during anodization processes, can be used to determine the optimum anodization time. It is found that the growth rate of TiO2 NTAs is improved significantly under high field, which is nearly 8 times faster than that under low fields (40-60 V). The length and growth rate of the nanotubes are further increased with the increase of fluoride content in the electrolyte.

  8. Lithium ion conductive behavior of TiO2 nanotube/ionic liquid matrices

    PubMed Central

    2014-01-01

    A series of TiO2 nanotube (TNT)/ionic liquid matrices were prepared, and their lithium ion conductive properties were studied. SEM images implied that ionic liquid was dispersed on the whole surface of TNT. Addition of TNT to ionic liquid (1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide (BMImTFSA)) resulted in significant increase of ionic conductivity. Furthermore, lithium transference number was also largely enhanced due to the interaction of anion with TNT. Vogel-Fulcher-Tammann parameter showed higher carrier ion number for TNT/BMImTFSA in comparison with BMImTFSA. PMID:25313300

  9. High-efficiency dye-sensitized solar cells based on robust and both-end-open TiO2 nanotube membranes

    PubMed Central

    2011-01-01

    In the present work, dye-sensitized solar cells (DSSCs) were fabricated by incorporating transparent electrodes of ordered free-standing TiO2 nanotube (TNT) arrays with both ends open transferred onto fluorine-doped tin oxide (FTO) conductive glass. The high-quality TiO2 membranes used here were obtained by a self-detaching technique, with the superiorities of facile but reliable procedures. Afterwards, these TNT membranes can be easily transferred to FTO glass substrates by TiO2 nanoparticle paste without any crack. Compared with those DSSCs consisting of the bottom-closed membranes or attached to Ti substrate, the carefully assembled and front-side illuminated DSSCs showed an enhanced solar energy conversion efficiency as high as 5.32% of 24-μm-thick TiO2 nanotube membranes without further treatments. These results reveal that by facilitating high-quality membrane synthesis, this kind of DSSCs assembly with optimized tube configuration can have a fascinating future. PMID:21794157

  10. Anodization parameters influencing the morphology and electrical properties of TiO2 nanotubes for living cell interfacing and investigations.

    PubMed

    Khudhair, D; Bhatti, A; Li, Y; Hamedani, H Amani; Garmestani, H; Hodgson, P; Nahavandi, S

    2016-02-01

    Nanotube structures have attracted tremendous attention in recent years in many applications. Among such nanotube structures, titania nanotubes (TiO2) 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 TiO2 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 TiO2 directly impacts the biocompatibility aspects of the titanium in terms of cell proliferation, adhesion and mineralization. Similarly, TiO2 nanotube wall thickness of 30-40nm 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.

  11. Antibacterial Activity of As-Annealed TiO2 Nanotubes Doped with Ag Nanoparticles against Periodontal Pathogens

    PubMed Central

    Yeniyol, Sinem; He, Zhiming; Yüksel, Behiye; Boylan, Robert Joseph; Ürgen, Mustafa; Özdemir, Tayfun; Ricci, John Lawrence

    2014-01-01

    It is important to develop functional transmucosal implant surfaces that reduce the number of initially adhering bacteria and they need to be modified to improve the anti-bacterial performance. Commercially pure Ti sheets were anodized in an electrolyte containing ethylene glycol, distilled water and ammonium fluoride at room temperature to produce TiO2 nanotubes. These structures were then annealed at 450°C to transform them to anatase. As-annealed TiO2 nanotubes were then treated in an electrolyte containing 80.7 g/L NiSO4·7H2O, 41 g/L MgSO4·7H2O, 45 g/L H3BO3, and 1.44 g/L Ag2SO4 at 20°C by the application of 9 V AC voltage for doping them with silver. As-annealed TiO2 nanotubes and as-annealed Ag doped TiO2 nanotubes were evaluated by SEM, FESEM, and XRD. Antibacterial activity was assessed by determining the adherence of A. actinomycetemcomitans, T. forsythia, and C. rectus to the surface of the nanotubes. Bacterial morphology was examined using an SEM. As-annealed Ag doped TiO2 nanotubes revealed intense peak of Ag. Bacterial death against the as-annealed Ag doped TiO2 nanotubes were detected against A. actinomycetemcomitans, T. forsythia, and C. rectus indicating antibacterial efficacy. PMID:25202230

  12. The effect of dye-sensitized solar cell based on the composite layer by anodic TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Yang, Jun Hyuk; Kim, Kyung Hwan; Bark, Chung Wung; Choi, Hyung Wook

    2014-12-01

    TiO2 nanotube arrays are very attractive for dye-sensitized solar cells (DSSCs) owing to their superior charge percolation and slower charge recombination. Highly ordered, vertically aligned TiO2 nanotube arrays have been fabricated by a three-step anodization process. Although the use of a one-dimensional structure provides an enhanced photoelectrical performance, the smaller surface area reduces the adsorption of dye on the TiO2 surface. To overcome this problem, we investigated the effect of DSSCs constructed with a multilayer photoelectrode made of TiO2 nanoparticles and TiO2 nanotube arrays. We fabricated the novel multilayer photoelectrode via a layer-by-layer assembly process and thoroughly investigated the effect of various structures on the sample efficiency. The DSSC with a four-layer photoelectrode exhibited a maximum conversion efficiency of 7.22% because of effective electron transport and enhanced adsorption of dye on the TiO2 surface.

  13. The effect of dye-sensitized solar cell based on the composite layer by anodic TiO2 nanotubes.

    PubMed

    Yang, Jun Hyuk; Kim, Kyung Hwan; Bark, Chung Wung; Choi, Hyung Wook

    2014-01-01

    TiO2 nanotube arrays are very attractive for dye-sensitized solar cells (DSSCs) owing to their superior charge percolation and slower charge recombination. Highly ordered, vertically aligned TiO2 nanotube arrays have been fabricated by a three-step anodization process. Although the use of a one-dimensional structure provides an enhanced photoelectrical performance, the smaller surface area reduces the adsorption of dye on the TiO2 surface. To overcome this problem, we investigated the effect of DSSCs constructed with a multilayer photoelectrode made of TiO2 nanoparticles and TiO2 nanotube arrays. We fabricated the novel multilayer photoelectrode via a layer-by-layer assembly process and thoroughly investigated the effect of various structures on the sample efficiency. The DSSC with a four-layer photoelectrode exhibited a maximum conversion efficiency of 7.22% because of effective electron transport and enhanced adsorption of dye on the TiO2 surface.

  14. Hierarchical Nanotube-Constructed Porous TiO2-B Spheres for High Performance Lithium Ion Batteries

    NASA Astrophysics Data System (ADS)

    Cai, Yi; Wang, Hong-En; -Zhuan Huang, Shao; Jin, Jun; Wang, Chao; Yu, Yong; Li, Yu; Su, Bao-Lian

    2015-07-01

    Hierarchically structured porous TiO2-B spheres have been synthesized via a hydrothermal process using amorphous titania/oleylamine composites as a self-sacrificing template. The TiO2-B spheres are constructed by interconnected nanotubes and possess a high specific surface area of 295 m2 g-1. When evaluated as an anode material in lithium-half cells, the as-obtained TiO2-B material exhibits high and reversible lithium storage capacity of 270 mA h g-1 at 1 C (340 mA g-1), excellent rate capability of 221 mA h g-1 at 10 C, and long cycle life with over 70% capacity retention after 1000 cycles at 10 C. The superior electrochemical performance of TiO2-B material strongly correlates to the synergetic superiorities with a combination of TiO2-B polymorph, hierarchically porous structure, interconnected nanotubes and spherical morphology. Post-mortem structural analyses reveal some discrete cubic LiTiO2 nanodots formed on the outer surfaces of TiO2-B nanotubes, which might account for the slight capacity loss upon prolonged electrochemical cycling.

  15. Application of TiO2 nanoparticles coated multi-wall carbon nanotube to dye-sensitized solar cells.

    PubMed

    Chang, Ho; Kao, Mu-Jung; Huang, Kuohsiu-David; Hsieh, Tung-Jung; Chien, Shu-Hua

    2010-11-01

    This study uses the sol-gel method to prepare TiO2 nanoparticle, and further applies TiO2 nanoparticle coating on the surface of the multi-wall carbon nanotube (MWCNT). As a result, TiO2-CNT composite nanoparticles are prepared to serve as photoelectrode material in dye-sensitized solar cell (DSSC). First, after acid treatment of MWCNT is used to remove impurities. Then, the sol-gel method is employed to prepare TiO2-CNT composite nanopowder. X-ray diffraction (XRD) pattern shows that after the TiO2 in TiO2-CNT composite nanopowder has been thermally treated at 450 degrees C, it can be completely changed to anatase phase. Furthermore, as shown from the SEM image, TiO2 has been successfully coated on CNT. The photoelectrode of DSSC is prepared using the electrophoretic deposition method (EPD) to mix the Degassa P25 TiO2 nanoparticles with TiO2-CNT powder for deposition on the indium tin oxide (ITO) conductive glass. After secondary EPD, a thin film of TiO2/CNTs with thickness 17 microm can be acquired. For the prepared TiO2-CNT composite nanoparticles, since MWCNT can increase the short-circuit current density of DSSC, the light-to-electricity conversion efficiency of DSSC can be effectively increased. Experimental results show that the photoelectric conversion efficiency of DSSC using CNT/TiO2 photoelectrode and N719 dye is increased by 41% from the original 3.45% to 4.87%.

  16. Dependence of TiO2 nanotube microstructural and electronic properties on water splitting

    NASA Astrophysics Data System (ADS)

    Freitas, R. G.; Santanna, M. A.; Pereira, E. C.

    2014-04-01

    In this work, TiO2 nanotubes were prepared by anodization in ionic liquid at 10 °C and 20 °C. Different tube diameters (50.8 nm and 70.5 nm) were obtained, and both of them exhibited an anatase phase with distinct crystallite sizes and lattice strains. The increase in the crystallite size led to a decrease in the grain boundary surface area, which could be associated with the recombination centers of the photogenerated charge carriers. Electrochemical impedance spectroscopy was used to correlate the water splitting photoactivity with the charge transfer resistance and the apparent roughness. A schematic representation of the nanotube structures consisting of two layers, compact and porous, proved to be appropriate to clarify the obtained results.

  17. Photovoltaic performance of dye-sensitized solar cells using TiO2 nanotubes aggregates produced by hydrothermal synthesis

    NASA Astrophysics Data System (ADS)

    Chen, Qiufan; Sun, Xiaonan; Liu, Anping; Zhang, Qifeng; Cao, Guozhong; Zhou, Xiaoyuan

    2015-09-01

    This paper reports the synthesis, detailed structural characterization of aggregated TiO2 nanotubes and the application of such aggregated TiO2 nanotubes as photoelectrodes in solar cells (dye sensitized DSCs). A maximum overall conversion efficiency of 7.9% has been achieved, which use conventional dyes without any additional chemical treatments under circumstances of an open-circuit voltage of 710 mV, a short-circuit current density of 16.8mA/cm2, and a fill factor of 66%. This impressive performance is believed to attribute to the micron-sized aggregate structure which may be favorable for light harvesting, the desired high specific surface area and pure anatase phase for dye absorption. This significant improvement in the conversion efficiency indicates that DSCs based on aggregated TiO2 nanotubes are a promising alternative to semiconductor-based solar cells.

  18. MFI-type (ZSM-5) zeolite-filled TiO2 nanotubes for enhanced photocatalytic activity.

    PubMed

    Paramasivam, I; Avhale, A; Inayat, A; Bösmann, A; Schmuki, P; Schwieger, W

    2009-06-03

    The present work demonstrates enhanced photocatalytic activity for zeolite-filled TiO2 nanotubes. ZSM-5 zeolite nanocrystals were grown on and into a TiO2 nanotubular skeleton (TiNT/ZSM-5) by multi-step hydrothermal synthesis consisting of in situ seeding and multiple in situ crystallization (MISC). The resulting zeolite nanocrystals were in the range of a few nanometers and they adhere well to the nanotubular inner walls. After crystallization, the photocatalytic activity of this zeolite-filled nanotube catalyst system was compared with neat anatase TiO2 nanotube (TiNT) and with calcined ZSM-5 powder. The results show for TiNT/ZSM-5 a highly enhanced efficiency for the decomposition of acetophenone (used as an aromatic model organic pollutant).

  19. Effects of TiO2 nanotubes with different diameters on gene expression and osseointegration of implants in minipigs.

    PubMed

    Wang, Na; Li, Hongyi; Lü, Wulong; Li, Jinghui; Wang, Jinshu; Zhang, Zhenting; Liu, Yiran

    2011-10-01

    Titanium dioxide (TiO(2)) nanotubes can accelerate the adhesion and differentiation of osteoblasts, yet little is known how this nano-modified implant surface affects osseointegration at molecular level in vivo. The aim of this study was to investigate the effects of TiO(2) nanotubes with different diameters (30 nm, 70 nm and 100 nm) on biological attachment mechanism of implants to bone in vivo by studying the gene expression and bone formation around the implants. The histological features and fluorochrome labeling changes of bone around implants on the non-decalcified sections (at 3, 5 and 8 weeks after implantation) were investigated by using traditional light- and fluorescent microscopy, and the gene expression of alkaline phosphatase (ALP), osterix (Osx), collagen-I (Col-I) and tartrate-resistant acid phosphatase (TRAP) was examined by using real-time PCR at 1, 2, 3, 4 and 5 weeks after implantation. Comparing with machined titanium implants, a significant increase in bone-implant contact (BIC) and gene expression levels was found in the bone attached to implants with TiO(2) nanotubes, especially with 70 nm diameter nanotubes. At the same time, the sequential fluorescent labeling images illustrated dynamic bone deposition. In conclusion, TiO(2) nanotubes can modulate bone formation events at the bone-implant interface as to reach favorable molecular response and osseointegration; in addition, the diameters of nanotubes can be precisely controlled in order to obtain better bone formation.

  20. Incorporation of nitrogen into TiO2 thin films during PVD processes

    NASA Astrophysics Data System (ADS)

    Asenova, I.; Manova, D.; Mändl, S.

    2014-11-01

    In this paper we investigate the possibility of incorporating nitrogen into amorphous, photocatalytic TiO2 thin films, prepared at room temperature, during the growth process. The aim is to reduce the bandgap of the UV active thin films. Physical vapor deposition experiments employing a titanium vacuum arc with gas backfill ranging from pure oxygen to pure nitrogen, are carried out. The resulting films are characterized for chemical composition, phase composition, optical properties and hydrophilicity in order to determine a correlation between gas composition and thin film properties. The experimental results point that a visible change in the band structure of the deposited layers is achieved.

  1. Adsorption of Hg(II) from aqueous solutions using TiO2 and titanate nanotube adsorbents

    NASA Astrophysics Data System (ADS)

    López-Muñoz, María-José; Arencibia, Amaya; Cerro, Luis; Pascual, Raquel; Melgar, Álvaro

    2016-03-01

    Titania and titanate nanotubes were evaluated as adsorbents for the removal of Hg(II) from aqueous solution. Commercial titanium dioxide (TiO2-P25, Evonik), a synthesized anatase sample obtained by the sol-gel method (TiO2-SG) and titanate nanotubes (TNT) prepared via hydrothermal treatment were compared. Mercury adsorption was analysed by kinetic and equilibrium experiments, studying the influence of pH and the type of adsorbents. The kinetics of Hg(II) adsorption on titania and titanate nanotubes could be well described by the pseudo-second order model. It was found that the process is generally fast with small differences between adsorbents, which cannot be explained by their dissimilarities in textural properties. Equilibrium isotherm data were best fitted with the Sips isotherm model. The maximum adsorption capacities of Hg(II) were achieved with titanate nanotubes sample, whereas between both titania samples, TiO2-SG exhibited the highest mercury uptake. For all adsorbents, adsorption capacities were enhanced as pH was increased, achieving at pH 10 Hg(II) adsorption capacities of 100, 121, and 140 mg g-1 for TiO2-P25, TiO2-SG, and TNT, respectively. Differences between samples were discussed in terms of their crystalline phase composition and chemical nature of both, mercury species and surface active sites.

  2. Photocatalytic Activity and Photocurrent Properties of TiO2 Nanotube Arrays Influenced by Calcination Temperature and Tube Length

    NASA Astrophysics Data System (ADS)

    Hou, Jian; Zhang, Min; Yan, Guotian; Yang, Jianjun

    2012-06-01

    In this article, titanium oxide nanotube arrays (TiO2-NTAs) were fabricated by anodic oxidation in an ethylene glycol (EG) electrolyte solution containing 0.25 wt.% NH4F. By varying anodized time and annealed temperature, the obtained nanotube arrays behaved different photocatalytic (PC) activities and photocurrent properties. These samples were characterized by scanning electronic microscope (SEM), X-ray powder diffraction (XRD). It was indicated in SEM images that TiO2 nanotube manifests highly ordered structure which, however, has been completely destroyed when the temperature comes to 800°C. XRD manifested that TiO2 nanotubes with various kinds of length all possessed anatase crystallite when annealed at 500°C; meanwhile, with certain length, TiO2-NTAs annealed at series calcination temperature range of 300-600°C also presented anatase crystallite, which is gradually enhanced with the increment of temperature. At 700°C, mixed structure was observed which was made up of proportions of overwhelming anatase and toothful rutile. Methyl blue (MB) degradation and photocurrent measurement testified that TiO2-NTAs under 4 h oxidation and 3 h of 600°C calcination manifested the highest activity and photocurrent density.

  3. Adsorption of carbon dioxide on amine-modified TiO2 nanotubes.

    PubMed

    Song, Fujiao; Zhao, Yunxia; Zhong, Qin

    2013-03-01

    TiO2 nanotubes (TiNT) were prepared by a hydrothermal treatment and modified by three kinds of amines, namely ethylenediamine, polyetherimide and tetraethylenepentamine (TEPA), to study their CO2 adsorption properties from gas streams. The resultant samples were characterized by X-ray diffraction, transmission electron microscopy, and infrared spectroscopy, as well as low temperature N2 adsorption. CO2 capture was investigated in a dynamic packed column at 30 degrees C. TEPA-modified TiO2 nanotubes showed the highest adsorption capacity of 167.64 mg/g because it had the highest amino-group content among the three amines. CO2 fixation on TiNT impregnated by TEPA was investigated at 30, 50, and 70 degrees C, and the adsorption capacity increased slightly with temperature. Following the adsorption step, the sorbents were regenerated by temperature programmed desorption, and the TiNT-TEPA sample, as CO2 sorbent, was found to be readily regenerated and energy-efficient. The cycle test also revealed that the TiNT-TEPA adsorbent is fairly stable, with only a 5% drop in the adsorption capacity after 10 adsorption/desorption cycles. In addition, the CO2 adsorption behavior was investigated with the deactivation model, and which showed an excellent prediction for the TiNT-TEPA breakthrough curves.

  4. Electrolyte Concentration Effect of a Photoelectrochemical Cell Consisting of TiO 2 Nanotube Anode

    DOE PAGES

    Ren, Kai; Gan, Yong X.; Nikolaidis, Efstratios; ...

    2013-01-01

    The photoelectrochemical responses of a TiO 2 nanotube anode in ethylene glycol (EG), glycerol, ammonia, ethanol, urea, and Na 2 S electrolytes with different concentrations were investigated. The TiO 2 nanotube anode was highly efficient in photoelectrocatalysis in these solutions under UV light illumination. The photocurrent density is obviously affected by the concentration change. Na 2 S generated the highest photocurrent density at 0, 1, and 2 V bias voltages, but its concentration does not significantly affect the photocurrent density. Urea shows high open circuit voltage at proper concentration and low photocurrent at different concentrations. Externally applied bias voltage ismore » also an important factor that changes the photoelectrochemical reaction process. In view of the open circuit voltage, EG, ammonia, and ethanol fuel cells show the trend that the open circuit voltage (OCV) increases with the increase of the concentration of the solutions. Glycerol has the highest OCV compared with others, and it deceases with the increase in the concentration because of the high viscosity. The OCV of the urea and Na 2 S solutions did not show obvious concentration effect.« less

  5. TiO2 nanotubes as animal drug delivery system and in vitro controlled release.

    PubMed

    Lai, Shuting; Zhang, Wei; Liu, Fang; Wu, Cui; Zeng, Dongping; Sun, Yongxue; Xu, Yuehua; Fang, Yueping; Zhou, Wuyi

    2013-01-01

    The enrofloxacin hydrochloride (Enro), an anti-inflammatory drug for the animals, was loaded on the TNTs through physical absorption due to the high specific surface area and excellent surface activity of the TiO2 nanotubes. The samples were characterized by XRD, BET, TEM, TG and FTIR. The in vitro controlled release behavior at different temperatures was studied in detail. The results showed that the obtained TNTs were uniform and mainly amorphous crystal phase with a diameter of 10-15 nm and a length of 350-400 nm. By investigating the effect of the hydrothermal reaction process of the obtained TiO2 nanotubes and the drug loading frequency on the loading content of Enro drugs, the results indicated that the increasing loading frequency of the drug was available for the drug loading and the maximum loading content of drug reached to 33.28%. Enro-TNTs performed a better release profile at low temperature than at high temperature in PBS solution. The Higuchi square root models are suitable to explain the in vitro drug release behavior of Enro from Enro-TNTs.

  6. Antibacterial activity and increased bone marrow stem cell functions of Zn-incorporated TiO2 coatings on titanium.

    PubMed

    Hu, H; Zhang, W; Qiao, Y; Jiang, X; Liu, X; Ding, C

    2012-02-01

    In this work, zinc was incorporated into TiO2 coatings on titanium by plasma electrolytic oxidation to obtain the implant with good bacterial inhibition ability and bone-formability. The porous and nanostructured Zn-incorporated TiO2 coatings are built up from pores smaller than 5 μm and grains 20-100 nm in size, in which the element Zn exists as ZnO. The results obtained from the antibacterial studies suggest that the Zn-incorporated TiO2 coatings can greatly inhibit the growth of both Staphylococcus aureus and Escherichia coli, and the ability to inhibit bacteria can be improved by increasing the Zn content in the coatings. Moreover, the in vitro cytocompatibility evaluation demonstrates that the adhesion, proliferation and differentiation of rat bone marrow stem cells (bMSC) on Zn-incorporated coatings are significantly enhanced compared with Zn-free coating and commercially pure Ti plate, and no cytotoxicity appeared on any of the Zn-incorporated TiO2 coatings. Moreover, bMSC express higher level of alkaline phosphatase activity on Zn-incorporated TiO2 coatings and are induced to differentiate into osteoblast cells. The better antibacterial activity, cytocompatibility and the capability to promote bMSC osteogenic differentiation of Zn-incorporated TiO2 coatings may be attributed to the fact that Zn ions can be slowly and constantly released from the coatings. In conclusion, innovative Zn-incorporated TiO2 coatings on titanium with excellent antibacterial activity and biocompatibility are promising candidates for orthopedic and dental implants.

  7. N-doped TiO2 Nanotubes as an Effective Additive to Improve the Catalytic Capability of Methanol Oxidation for Pt/Graphene Nanocomposites

    PubMed Central

    Wang, Xiaohua; Li, Yueming; Liu, Shimin; Zhang, Long

    2016-01-01

    N-doped TiO2 nanotubes have been prepared as additives to improve the catalytic capability of Pt/graphene composites in methanol oxidation reactions. Electrochemical experiments show that the catalytic performance of Pt/graphene composites has been greatly improved by the introduction of N-doped TiO2 nanotubes.

  8. Use of ion-assisted techniques for determining the structure of TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Renz, Renata P.; Vargas, André L. M.; Hübler, Roberto

    2015-12-01

    In recent years, several researchers have reported obtaining titanium dioxide nanotubes presenting a variety of advanced and functional properties for high-performance applications, e.g., for solar and fuel cells, gas sensor, self-cleaning and biomedical devices. Electrochemical oxidation of titanium has been widely used as a method for fabrication of self-organized titanium oxide nanotubes (TiO2 NTs), since it is a simple and inexpensive process, which allows a great control over the size and configuration of the formed structure. Normally, the morphological and structural characterizations are based on images from scanning or transmission electron microscopy. The use of characterization techniques assisted by energetic ion beams, such as RBS or MEIS, can simultaneously evaluate the composition and structural properties of the nanotubes. In this work, titanium oxide nanotubes were obtained by electrochemical oxidation of commercially pure titanium via constant-voltage experiments varying the growth time and the potential applied in order to access the formation dynamics of the NTs, including inner and outer diameters as function of the length, and the formation of the end lace type porous layer. The characterizations made by RBS were compared by analysis of top and cross-sectional FEG-SEM images demonstrating a good compromise between them.

  9. Nano Size Effects of TiO2 Nanotube Array on the Glioma Cells Behavior

    PubMed Central

    Yang, He; Qin, Xiaofei; Tian, Ang; Zhang, Dongyong; Xue, Xiangxin; Wu, Anhua

    2013-01-01

    In order to investigate the interplay between the cells and TiO2 nanotube array, and to explore the ability of cells to sense the size change in nano-environment, we reported on the behavior of glioma C6 cells on nanotube array coatings in terms of proliferation and apoptosis. The behavior of glioma C6 cells was obviously size-dependent on the coatings; the caliber with 15 nm diameter provided effective spacing to improve the cells proliferation and enhanced the cellular activities. C6 cells’ biological behaviors showed many similar tendencies to many phorocytes; the matching degree of geometry between nanotube and integrin defined that a spacing of 15 nm was optimal for inducing signals to nucleus, which results in achieving maximum activity of glioma cells. In addition, the immune behavior of cells was studied, a variety of inflammatory mediator’s gene expression levels were controlled by the nanoscale dimension, the expressions of IL-6 and IL-10 were higher on 30 nm than on 15 nm nanotube. PMID:23344031

  10. Fabrication of thin film TiO2 nanotube arrays on Co-28Cr-6Mo alloy by anodization.

    PubMed

    Ni, Jiahua; Frandsen, Christine J; Noh, Kunbae; Johnston, Gary W; He, Guo; Tang, Tingting; Jin, Sungho

    2013-04-01

    Titanium oxide (TiO2) nanotube arrays were prepared by anodization of Ti/Au/Ti trilayer thin film DC sputtered onto forged and cast Co-28Cr-6Mo alloy substrate at 400 °C. Two different types of deposited film structures (Ti/Au/Ti trilayer and Ti monolayer), and two deposition temperatures (room temperature and 400 °C) were compared in this work. The concentrations of ammonium fluoride (NH4F) and H2O in glycerol electrolyte were varied to study their effect on the formation of TiO2 nanotube arrays on a forged and cast Co-28Cr-6Mo alloy. The results show that Ti/Au/Ti trilayer thin film and elevated temperature sputtered films are favorable for the formation of well-ordered nanotube arrays. The optimized electrolyte concentration for the growth of TiO2 nanotube arrays on forged and cast Co-28Cr-6Mo alloy was obtained. This work contains meaningful results for the application of a TiO2 nanotube coating to a CoCr alloy implant for potential next-generation orthopedic implant surface coatings with improved osseointegrative capabilities.

  11. Photoactive layered nanocomposites obtained by direct transferring of anodic TiO2 nanotubes to commodity thermoplastics

    NASA Astrophysics Data System (ADS)

    Sanz, Ruy; Buccheri, Maria Antonietta; Zimbone, Massimo; Scuderi, Viviana; Amiard, Guillaume; Impellizzeri, Giuliana; Romano, Lucia; Privitera, Vittorio

    2017-03-01

    TiO2 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 TiO2 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 TiO2 nanotubes on titanium. In addition, the nanocomposites and TiO2 nanotubes on titanium present similar antibacterial properties under 1 mW cm-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.

  12. Fabrication of thin film TiO2 nanotube arrays on Co-28Cr-6Mo alloy by anodization

    PubMed Central

    Ni, Jiahua; Frandsen, Christine J.; Noh, Kunbae; Johnston, Gary W.; He, Guo; Tang, Tingting; Jin, Sungho

    2014-01-01

    Titanium oxide (TiO2) nanotube arrays were prepared by anodization of Ti/Au/Ti trilayer thin film DC sputtered onto forged and cast Co-28Cr-6Mo alloy substrate at 400 °C. Two different types of deposited film structures (Ti/Au/Ti trilayer and Ti monolayer), and two deposition temperatures (room temperature and 400 °C) were compared in this work. The concentrations of ammonium fluoride (NH4F) and H2O in glycerol electrolyte were varied to study their effect on the formation of TiO2 nanotube arrays on a forged and cast Co-28Cr-6Mo alloy. The results show that Ti/Au/Ti trilayer thin film and elevated temperature sputtered films are favorable for the formation of well-ordered nanotube arrays. The optimized electrolyte concentration for the growth of TiO2 nanotube arrays on forged and cast Co-28Cr-6Mo alloy was obtained. This work contains meaningful results for the application of a TiO2 nanotube coating to a CoCr alloy implant for potential next-generation orthopedic implant surface coatings with improved osseointegrative capabilities. PMID:23827596

  13. Enhancement of photoelectrochemical and photocathodic protection properties of TiO2 nanotube arrays by simple surface UV treatment

    NASA Astrophysics Data System (ADS)

    Zhang, Tingting; Liu, Yupeng; Liang, Jun; Wang, Daoai

    2017-02-01

    A simple and efficient surface treatment method toward practical applications to enhance photo response of TiO2 nanotube arrays (NTs) photoelectrode was reported. TiO2 NTs were prepared by two-step electrochemical anodization methods, following by surface ultra violet light (UV) illumination treatment, which can produce amounts of hydroxyl groups on the surface of TiO2 NTs photoelectrode. The photoelectrochemical measurements demonstrate that the photocurrent density of the UV treated TiO2 NTs photoelectrode enhances by 50% than that of the pristine TiO2 NTs photoelectrode. More interestingly, the decayed photocurrent density of TiO2 NTs can recover the high value by illumination treatment again after using/storing for several days. Additionally, open circuit potential, tafel curves and electrochemical impedance spectroscopy measurements exhibit that the UV illumination treatment for TiO2 NTs photoelectrode is an easy and effective strategy to protect 304 stainless steel from corrosion by photogenerated cathode protection.

  14. Electrochemical performance and biosensor application of TiO2 nanotube arrays with mesoporous structures constructed by chemical etching.

    PubMed

    Wang, Jinwen; Xu, Guangqing; Zhang, Xu; Lv, Jun; Zhang, Xinyi; Zheng, Zhixiang; Wu, Yucheng

    2015-04-28

    Novel mesoporous TiO2 nanotube arrays (TiO2 NTAs) were synthesized by an anodization method combined with chemical etching in HF solution, and the electrochemical performance was studied. Glucose oxidase (GOx) was immobilized on the mesoporous TiO2 NTAs to achieve an efficient biosensor for amperometric detection of glucose. The morphology, structure, component and electrochemical performance of mesoporous TiO2 NTAs were characterized by scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffractometry, X-ray photoelectron spectrometry and an electrochemical workstation, respectively. The influence of the mesoporous structure on the electrochemical performance is discussed in detail by comparing the cyclic voltammograms and electrochemical impedance spectrum of TiO2 and mesoporous TiO2 NTAs in different conditions. High electrochemical active surface area and electron transfer rate play key roles in enhancing the electrochemical performance of mesoporous TiO2 NTAs. When used as the basis of a biosensor, the amperometric response of glucose on a GOx/TiO2-0.5 NTAs electrode is linearly proportion to the glucose concentration in the range from 0.1 to 6 mM with a sensitivity of 0.954 μA mM(-1) cm(-2), which is 14.3 times that of un-etched GOx/TiO2 NTAs.

  15. The heterojunction effects of TiO2 nanotubes fabricated by atomic layer deposition on photocarrier transportation direction

    PubMed Central

    2012-01-01

    The heterojunction effects of TiO2 nanotubes on photoconductive characteristics were investigated. For ITO/TiO2/Si diodes, the photocurrent is controlled either by the TiO2/Si heterojunction (p-n junction) or the ITO-TiO2 heterojunction (Schottky contact). In the short circuit (approximately 0 V) condition, the TiO2-Si heterojunction dominates the photocarrier transportation direction due to its larger space-charge region and potential gradient. The detailed transition process of the photocarrier direction was investigated with a time-dependent photoresponse study. The results showed that the diode transitioned from TiO2-Si heterojunction-controlled to ITO-TiO2 heterojunction-controlled as we applied biases from approximately 0 to -1 V on the ITO electrode. PMID:22525197

  16. Are TiO2 nanotubes worth using in photocatalytic purification of air and water?

    PubMed

    Pichat, Pierre

    2014-09-19

    Titanium dioxide nanotubes (TNT) have mainly been used in dye sensitized solar cells, essentially because of a higher transport rate of electrons from the adsorbed photo-excited dye to the Ti electrode onto which TNT instead of TiO2 nanoparticles (TNP) are attached. The dimension ranges and the two main synthesis methods of TNT are briefly indicated here. Not surprisingly, the particular and regular texture of TNT was also expected to improve the photocatalytic efficacy for pollutant removal in air and water with respect to TNP. In this short review, the validity of this expectation is checked using the regrettably small number of literature comparisons between TNT and commercialized TNP referring to films of similar thickness and layers or slurries containing an equal TiO2 mass. Although the irradiated geometrical area differed for each study, it was identical for each comparison considered here. For the removal of toluene (methylbenzene) or acetaldehyde (ethanal) in air, the average ratio of the efficacy of TNT over that of TiO2 P25 was about 1.5, and for the removal of dyes in water, it was around 1. This lack of major improvement with TNT compared to TNP could partially be due to TNT texture disorders as seems to be suggested by the better average performance of anodic oxidation-prepared TNT. It could also come from the fact that the properties influencing the efficacy are more numerous, their interrelations more complex and their effects more important for pollutant removal than for dye sensitized solar cells and photoelectrocatalysis where the electron transport rate is the crucial parameter.

  17. Improved photoanode structure based on anodic titania nanotube array covered by TiO2-NPs/nanographite composite layer for ETA-cells

    NASA Astrophysics Data System (ADS)

    Gavrilin, I. M.; Dronov, A. A.; Shilyaeva, Yu I.; Lebedev, E. A.; Kuzmicheva, M. S.; Savchuk, T. P.; Gavrilov, S. A.

    2016-08-01

    This work is devoted to the morphology and electrical properties optimization of flexible photoanodes based on anodic titanium oxide nanotubular arrays (TiO2-NTAs) for solar cells with extremely thin absorbing layer (ETA-cells) by TiO2-nanographite thin composite layer formation on the TiO2-NTAs surface. First, the carbon doped TiO2-NTAs were synthesized by annealing of the as-anodized TiO2-NTAs in argon without foreign carbonaceous precursor. The residual ethylene glycol absorbed on the nanotube wall during anodization serves as the carbon source and the C species are uniformly distributed along the entire nanotube to form the C-TiO2 NTAs. Further decorating of C-TiO2-NTAs surface by TiO2 nanoparticles to form the TiO2-nanographite (NG) composite layer with high conductivity and increased photoanode effective area showed improved ETA-cells performance.

  18. Comparative study on the process behavior and reaction kinetics in sonocatalytic degradation of organic dyes by powder and nanotubes TiO2.

    PubMed

    Pang, Yean Ling; Abdullah, Ahmad Zuhairi

    2012-05-01

    Sonocatalytic degradation of various organic dyes (Congo Red, Reactive Blue 4, Methyl Orange, Rhodamine B and Methylene Blue) catalyzed by powder and nanotubes TiO(2) was studied. Both catalysts were characterized using transmission electron microscope (TEM), surface analyzer, Raman spectroscope and thermal gravimetric analyzer (TGA). Sonocatalytic activity of powder and nanotubes TiO(2) was elucidated based on the degradation of various organic dyes. The former catalyst was favorable for treatment of anionic dyes, while the latter was more beneficial for cationic dyes. Sonocatalytic activity of TiO(2) nanotubes could be up to four times as compared to TiO(2) powder under an ultrasonic power of 100 W and a frequency of 42 kHz. This was associated with the higher surface area and the electrostatic attraction between dye molecules and TiO(2) nanotubes. Fourier transform-infrared spectrometer (FT-IR) was used to identify changes that occurred on the functional group in Rhodamine B molecules and TiO(2) nanotubes after the reaction. Sonocatalytic degradation of Rhodamine B by TiO(2) nanotubes apparently followed the Langmuir-Hinshelwood adsorption kinetic model with surface reaction rate of 1.75 mg/L min. TiO(2) nanotubes were proven for their high potential to be applied in sonocatalytic degradation of organic dyes.

  19. Non-metal doped TiO2 nanotube arrays for high efficiency photocatalytic decomposition of organic species in water

    NASA Astrophysics Data System (ADS)

    Szkoda, Mariusz; Siuzdak, Katarzyna; Lisowska-Oleksiak, Anna

    2016-10-01

    Titanium dioxide is a well-known photoactive semiconductor with a variety of possible applications. The procedure of pollutant degradation is mainly performed using TiO2 powder suspension. It can also be exploited an immobilized catalyst on a solid support. Morphology and chemical doping have a great influence on TiO2 activity under illumination. Here we compare photoactivity of titania nanotube arrays doped with non-metal atoms: nitrogen, iodine and boron applied for photodegradation of organic dye - methylene blue and terephtalic acid. The doped samples act as a much better photocatalyst in the degradation process of methylene blue and lead to the formation of much higher amount of hydroxyl radicals (•OH) than undoped TiO2 nanotube arrays. The use of a catalyst active under solar light illumination in the form of thin films on a stable substrate can be scaled up for an industrial application.

  20. Influences of Sr-Incorporated TiO2 Layer on the Photovoltaic Properties of Dye-Sensitized Solar Cells.

    PubMed

    Kim, Eun Seong; Kim, Dae-Hwan; Lee, Sang-Ju; Han, Yoon Soo

    2016-03-01

    Effects of a mixed overlayer composed of TiO2 and TiSrO3 on the performance of dye-sensitized solar cells (DSSCs) were investigated. The surface of TiO2 photoelectrode formed on F-doped SnO2 (FTO) was modified by soaking it in a TiCl4:SrCl2 mixed aqueous solution with various molar ratios and then calcining to produce the TiCl4:SrCl2-treated TiO2 photoelectrode (Ti:Sr-TiO2/FTO). The highest power conversion efficiency (PCE) was obtained from DSSC with Ti:Sr(7:3)-TiO2/FTO, which was prepared from the mixed solution with the molar ratio of 7:3 (TiOl4:SrCl2). An enhancement in short-circuit photocurrent (J(sc)) and open-circuit voltage (V(oc)) of DSSC with Ti:Sr(7:3)-TiO2/FTO was achieved, compared to those of the reference device with Ti:Sr(10:0)-TiC2/FTO (i.e., TiO2-coated TiO2/FTO). The incorporation of the mixed overlayer on the nanoporous TiO2 photoelectorde led to an improvement in the electron collection efficiency by a prolonged electron lifetime, thereby increasing the J(sc) value. The increase in V(oc) value of the device with Ti:Sr(7:3)-TiO2/FTO was due to the suppression of the charge recombination between injected electrons and I3(-) ions.

  1. Electrospun TiO2 nanofibers incorporated with graphene nanoflakes for energy conversion

    NASA Astrophysics Data System (ADS)

    Shinde, Manish A.; Alarifi, Ibrahim; Alharbi, Abdulaziz; Asmatulu, Ramazan

    2015-03-01

    Solar energy has been used in many different ways, including solar water heater, solar cooking, space heating, and electricity generation. The major drawbacks of the solar energy conversion systems are the lower conversion efficiency and higher manufacturing and replacement costs. In order to eliminate these obstacles, many studies were focused on the energy and cost efficiencies of the solar cells (particularly dye sensitized solar cells - DSSC and thin film solar cells). In the present study, TiO2 nanofibers incorporated with graphene nanoflakes (0, 2, 4, and 8wt.%) were produced using electrospinning process. The chemical utilized for the electrospinning process included poly (vinyle acetate), dimetylfomamide (DMF), titanium (IV) isopropoxide and acetic acid in the presence and absence of graphene nanoflakes. The resultant nanofibers were heat treated at 300 °C for 2 hrs in a standard oven to remove all the organic parts of the nanofibers, and then further heated up to 500 °C in an argon atmosphere for additional 12 hrs to crystalline the nanofibers. SEM, TEM and XRD studies showed that graphene and TiO2 nanofibers are well integrated in the nanofiber structures. This study may guide some of the scientists and engineers to tailor the energy bang gap structures of some of the semiconductor materials for different industrial applications, including DSSC, water splitting, catalyst, batteries, and fuel cell.

  2. TiO2 nanotubes infiltrated with nanoparticles for dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Pan, Xuan; Chen, Changhong; Zhu, Kai; Fan, Zhaoyang

    2011-06-01

    We present a detailed study of the infiltration of titanium dioxide (TiO2) nanotubes (NTs) with TiO2 nanoparticles (NPs) for dye sensitized solar cells (DSSCs). The aim is to combine the merits of the NP's high dye loading and high light harvesting capability with the NT's straight carrier transport path and high electron collection efficiency to improve the DSSC performance. On infiltrating NTs with TiCl4 solution followed by hydrothermal synthesis, 10 nm size NPs were observed to form a conformal and dense layer on the NT walls. Compared with the bare NT structure, dye loading of this mixed NT and NP structure is more than doubled. The overall photon conversion efficiencies of the fabricated DSSCs are improved by 152%, 107%, and 49% for 8, 13, and 20 µm long NTs, respectively. Electron transport and recombination parameters were extracted based on electrochemical impedance spectroscopy measurements. Although a slight reduction of electron lifetime was observed in the mixed structures due to enhanced recombination with a larger surface area, the diffusion length is still significantly longer than the NT length used, suggesting that most electrons are collected. In addition to dye loading and hence photocurrent increment, the photovoltage and filling factor were also improved in the mixed structure due to a low serial resistance, leading to the enhancement of the overall efficiency.

  3. TiO2 nanotubes infiltrated with nanoparticles for dye sensitized solar cells.

    PubMed

    Pan, Xuan; Chen, Changhong; Zhu, Kai; Fan, Zhaoyang

    2011-06-10

    We present a detailed study of the infiltration of titanium dioxide (TiO(2)) nanotubes (NTs) with TiO(2) nanoparticles (NPs) for dye sensitized solar cells (DSSCs). The aim is to combine the merits of the NP's high dye loading and high light harvesting capability with the NT's straight carrier transport path and high electron collection efficiency to improve the DSSC performance. On infiltrating NTs with TiCl(4) solution followed by hydrothermal synthesis, 10 nm size NPs were observed to form a conformal and dense layer on the NT walls. Compared with the bare NT structure, dye loading of this mixed NT and NP structure is more than doubled. The overall photon conversion efficiencies of the fabricated DSSCs are improved by 152%, 107%, and 49% for 8, 13, and 20 µm long NTs, respectively. Electron transport and recombination parameters were extracted based on electrochemical impedance spectroscopy measurements. Although a slight reduction of electron lifetime was observed in the mixed structures due to enhanced recombination with a larger surface area, the diffusion length is still significantly longer than the NT length used, suggesting that most electrons are collected. In addition to dye loading and hence photocurrent increment, the photovoltage and filling factor were also improved in the mixed structure due to a low serial resistance, leading to the enhancement of the overall efficiency.

  4. Detection of T4 polynucleotide kinase activity with immobilization of TiO2 nanotubes and amplification of Au nanoparticles.

    PubMed

    Wang, Guangfeng; He, Xiuping; Xu, Gang; Chen, Ling; Zhu, Yanhong; Zhang, Xiaojun; Wang, Lun

    2013-05-15

    Determination of nucleotide kinase activity is valuable due to its importance in regulating nucleic acid metabolism. Herein, we describe a strategy for simply and accurately determining nucleotide kinase activity by TiO2 nanotubes mediated signal transition and Au nanoparticles amplification. In this method, DNA containing 5'-hydroxyl group is self-assembled onto a gold electrode and used as a substrate for T4 polynucleotide kinase (PNK). By the specific immobilization affinity of TiO2 nanotubes with the phosphorylated DNA, TiO2 nanotubes were linked with phosphorylated substrate DNA on the electrode. And then Au nanoparticles modified 5'-phosphate DNA was conjugated with the TiO2 nanotubes and hybridized with methylene blue labeled signal DNA. Because gold nanoparticles have high loading of signal indicator methylene blue, the electrochemical signal is generated and amplified. It presents an excellent performance with wide linear range and low detection limit. Additionally, inhibition effects of some salts have also been investigated. The developed method is a potentially useful tool in researching the interactions between proteins and nucleic acids and provides a diversified platform for a kinase activity assay.

  5. Preparation and Application of TiO2 Nanotube Array Gas Sensor for SF6-Insulated Equipment Detection: a Review

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoxing; Gui, Yingang; Dong, Xingchen

    2016-06-01

    Since Zwilling and co-workers first introduced the electrochemical anodization method to prepare TiO2 nanotubes in 1999, it has attracted a lot of researches due to its outstanding gas response and selectivity, making it widely used in gas detection field. This review presents an introduction to the sensor applications of TiO2 nanotube arrays (TNTAs) in sulfur hexafluoride (SF6)-insulated equipment, which is used to evaluate and diagnose the insulation status of SF6-insulated equipment by detecting their typical decomposition products of SF6: sulfur dioxide (SO2), thionyl fluoride (SOF2), and sulfuryl fluoride (SO2F2). The synthesis and sensing properties of TiO2 nanotubes are discussed first. Then, it is followed by discussing the theoretical sensing to the typical SF6 decomposition products, SO2, SOF2, and SO2F2, which analyzes the sensing mechanism at the molecular level. Finally, the gas response of pure and modified TiO2 nanotubes sensor to SO2, SOF2, and SO2F2 is provided according to the change of resistance in experimental observation.

  6. TiO2 nanotube arrays grown in ionic liquids: high-efficiency in photocatalysis and pore-widening

    SciTech Connect

    Li, Huaqing; Qu, Jun; Cui, Qingzhou; Xu, Hanbing; Luo, Huimin; Chi, Miaofang; Meisner, Roberta Ann; Wang, Wei; Dai, Sheng

    2011-01-01

    Debris-free, long, well-separated TiO2 nanotube arrays were obtained using an ionic liquid (IL) as electrolyte. The high conductivity of IL resulted in fast pore widening and few contaminants from electrolyte decomposition leading to high photocatalytic efficiency in water splitting.

  7. Heterogeneous TiO2/V2O5/Carbon Nanotube Electrodes for Lithium-Ion Batteries.

    PubMed

    Kurttepeli, Mert; Deng, Shaoren; Mattelaer, Felix; Cott, Daire J; Vereecken, Philippe; Dendooven, Jolien; Detavernier, Christophe; Bals, Sara

    2017-03-08

    Vanadium pentoxide (V2O5) is proposed and investigated as a cathode material for lithium-ion (Li-ion) batteries. However, the dissolution of V2O5 during the charge/discharge remains as an issue at the V2O5-electrolyte interface. In this work, we present a heterogeneous nanostructure with carbon nanotubes supported V2O5/titanium dioxide (TiO2) multilayers as electrodes for thin-film Li-ion batteries. Atomic layer deposition of V2O5 on carbon nanotubes provides enhanced Li storage capacity and high rate performance. An additional TiO2 layer leads to increased morphological stability and in return higher electrochemical cycling performance of V2O5/carbon nanotubes. The physical and chemical properties of TiO2/V2O5/carbon nanotubes are characterized by cyclic voltammetry and charge/discharge measurements as well as electron microscopy. The detailed mechanism of the protective TiO2 layer to improve the electrochemical cycling stability of the V2O5 is unveiled.

  8. Preparation and Application of TiO2 Nanotube Array Gas Sensor for SF6-Insulated Equipment Detection: a Review.

    PubMed

    Zhang, Xiaoxing; Gui, Yingang; Dong, Xingchen

    2016-12-01

    Since Zwilling and co-workers first introduced the electrochemical anodization method to prepare TiO2 nanotubes in 1999, it has attracted a lot of researches due to its outstanding gas response and selectivity, making it widely used in gas detection field. This review presents an introduction to the sensor applications of TiO2 nanotube arrays (TNTAs) in sulfur hexafluoride (SF6)-insulated equipment, which is used to evaluate and diagnose the insulation status of SF6-insulated equipment by detecting their typical decomposition products of SF6: sulfur dioxide (SO2), thionyl fluoride (SOF2), and sulfuryl fluoride (SO2F2). The synthesis and sensing properties of TiO2 nanotubes are discussed first. Then, it is followed by discussing the theoretical sensing to the typical SF6 decomposition products, SO2, SOF2, and SO2F2, which analyzes the sensing mechanism at the molecular level. Finally, the gas response of pure and modified TiO2 nanotubes sensor to SO2, SOF2, and SO2F2 is provided according to the change of resistance in experimental observation.

  9. Effect of annealing temperature on wettability of TiO2 nanotube array films.

    PubMed

    Yang, Lei; Zhang, Miao; Shi, Shiwei; Lv, Jianguo; Song, Xueping; He, Gang; Sun, Zhaoqi

    2014-01-01

    Highly ordered TiO2 nanotube array (TN) films were prepared by anodization of titanium foil in a mixed electrolyte solution of glycerin and NH4F and then annealed at 200°C, 400°C, 600°C, and 800°C, respectively. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), water contact angle (WCA), and photoluminescence (PL). It was found that low temperature (below 600°C) has no significant influence on surface morphology, but the diameter of the nanotube increases from 40 to 50 nm with increasing temperature. At 800°C, the nanotube arrays are completely destroyed and only dense rutile film is observed. Samples unannealed and annealed at 200°C are amorphous. At 400°C, anatase phase appears. At 600°C, rutile phase appears. At 800°C, anatase phase changes into rutile phase completely. The wettability of the TN films shows that the WCAs for all samples freshly annealed at different temperatures are about 0°. After the annealed samples have been stored in air for 1 month, the WCAs increase to 130°, 133°, 135°, 141°, and 77°, respectively. Upon ultraviolet (UV) irradiation, they exhibit a significant transition from hydrophobicity to hydrophilicity. Especially, samples unannealed and annealed at 400°C show high photoinduced hydrophilicity.

  10. Recent advances on smart TiO2 nanotube platforms for sustainable drug delivery applications.

    PubMed

    Wang, Qun; Huang, Jian-Ying; Li, Hua-Qiong; Zhao, Allan Zi-Jian; Wang, Yi; Zhang, Ke-Qin; Sun, Hong-Tao; Lai, Yue-Kun

    To address the limitations of traditional drug delivery, TiO2 nanotubes (TNTs) are recognized as a promising material for localized drug delivery systems. With regard to the excellent biocompatibility and physicochemical properties, TNTs prepared by a facile electrochemical anodizing process have been used to fabricate new drug-releasing implants for localized drug delivery. This review discusses the development of TNTs applied in localized drug delivery systems, focusing on several approaches to control drug release, including the regulation of the dimensions of TNTs, modification of internal chemical characteristics, adjusting pore openings by biopolymer coatings, and employing polymeric micelles as drug nanocarriers. Furthermore, rational strategies on external conditions-triggered stimuli-responsive drug release for localized drug delivery systems are highlighted. Finally, the review concludes with the recent advances on TNTs for controlled drug delivery and corresponding prospects in the future.

  11. Effective approach to strengthening TiO2 nanotube arrays by using double or triple reinforcements

    NASA Astrophysics Data System (ADS)

    Sun, Mengwei; Yu, Dongliang; Lu, Linfeng; Ma, Weihua; Song, Ye; Zhu, Xufei

    2015-08-01

    Porous anodic TiO2 nanotube arrays (TNTAs) are fragile and also susceptible to be damaged during physical manipulation. Few studies have involved the improvement of the poor interfacial adhesion of TNTAs to the Ti substrate. Here, the poor adhesion of TNTAs was dramatically improved by appending an additional compact layer (ACL) formed at the interface between TNTAs and the Ti substrate. The adhesion of TNTAs with single-ACL increased with the increase of the ACL thickness. Furthermore, the reinforced TNTAs with double-ACL and triple-ACL have been successfully developed for the first time. The experimental results indicated that the critical load of the TNTAs with triple-ACL is roughly 5.8 times higher than that of the untreated TNTAs. The present results may be helpful to assemble less brittle and large area TNTAs for extensive applications.

  12. Electronic states and photoluminescence of TiO2 nanotubes with adsorbed surface oxygen

    NASA Astrophysics Data System (ADS)

    Liu, L. Z.; Xu, W.; Wu, X. L.; Zhang, Y. Y.; Chen, T. H.; Chu, Paul K.

    2012-03-01

    The electronic states associated with enhanced photocatalytic activity of anodic anatase TiO2 nanotubes (NTs) annealed in N2 and O2 are investigated by photoluminescence (PL). The NTs annealed in N2 show a green peak related to oxygen vacancies and its position blueshifts with deceasing temperature, whereas those annealed in O2 show a double peak at 475-600 nm and the energy separation increases with decreasing temperature. Spectral analysis and density function theory calculation disclose that the double peak results from residual oxygen vacancies and oxygen atoms on the NT wall and the increased energy separation arises from the larger difference between the inner and outer NT stress at low temperature.

  13. Recent advances on smart TiO2 nanotube platforms for sustainable drug delivery applications

    PubMed Central

    Wang, Qun; Huang, Jian-Ying; Li, Hua-Qiong; Zhao, Allan Zi-Jian; Wang, Yi; Zhang, Ke-Qin; Sun, Hong-Tao; Lai, Yue-Kun

    2017-01-01

    To address the limitations of traditional drug delivery, TiO2 nanotubes (TNTs) are recognized as a promising material for localized drug delivery systems. With regard to the excellent biocompatibility and physicochemical properties, TNTs prepared by a facile electrochemical anodizing process have been used to fabricate new drug-releasing implants for localized drug delivery. This review discusses the development of TNTs applied in localized drug delivery systems, focusing on several approaches to control drug release, including the regulation of the dimensions of TNTs, modification of internal chemical characteristics, adjusting pore openings by biopolymer coatings, and employing polymeric micelles as drug nanocarriers. Furthermore, rational strategies on external conditions-triggered stimuli-responsive drug release for localized drug delivery systems are highlighted. Finally, the review concludes with the recent advances on TNTs for controlled drug delivery and corresponding prospects in the future. PMID:28053530

  14. Photoelectrocatalytic degradation of triclosan on TiO2 nanotube arrays and toxicity change.

    PubMed

    Liu, Haijin; Cao, Xianglin; Liu, Guoguang; Wang, Yingling; Zhang, Nan; Li, Tong; Tough, Robert

    2013-09-01

    Triclosan, one of the most widely used disinfectants, has been found to be toxic to animals and human beings. In this paper, triclosan was degraded on TiO2 nanotube arrays, using a photoelectrocatalytic (PEC) process under UV illumination, with Na2SO4 as the supporting electrolyte. The effect of bias potential was investigated and the results showed that 0V was the most appropriate potential for the degradation of triclosan. In 30min, 78.7% of triclosan had degraded during the PEC process. Intermediate analysis showed that 2,7-dichlorodibenzodioxin (DCDD) had formed during the degradation. The toxicity change during the PEC process was investigated using a luminescent bacteria test, with the results demonstrating that the toxicity of the reaction liquid decreased at the beginning and subsequently increased to a stable level. The indications were that some intermediates such as 2,7-dichlorodibenzodioxin was more toxic and stable than triclosan in the solution.

  15. Transparent, well-aligned TiO(2) nanotube arrays with controllable dimensions on glass substrates for photocatalytic applications.

    PubMed

    Tan, Lee Kheng; Kumar, Manippady K; An, Wen Wen; Gao, Han

    2010-02-01

    Transparent, well-aligned TiO(2) nanotube arrays (NTAs) with controllable dimensions are grown on glass substrates via atomic layer deposition (ALD) of TiO(2) onto free-standing porous anodic alumina (PAA) templates. Photodegradation of aqueous methylene blue (MB) solution and solid stearic acid (SA) film using TiO(2) NTAs of various wall thicknesses are investigated. The Pd functionalized TiO(2) NTAs, with a wall thickness of 15 nm and height of 200 nm, has the highest photodegradation efficiency at 76% after 4 h of UV irradiation. These functionalized NTAs are able to photodegrade MB molecules completely as no obvious demethylated byproducts are observed during the process. It also demonstrates excellent photocatalytic activity for solid contaminants such as SA film. By using the ALD technique, the nanotube wall thickness can be precisely controlled so that it is sufficiently thin to be transparent while sufficiently thick for excellent photocatalytic performances. The transparent TiO(2) NTAs on glass substrates with excellent photocatalytic properties might have potential applications in self-cleaning coating, transparent electronics, and solar cells.

  16. Electrochemically conductive treatment of TiO2 nanotube arrays in AlCl3 aqueous solution for supercapacitors

    NASA Astrophysics Data System (ADS)

    Zhong, Wenjie; Sang, Shangbin; Liu, Yingying; Wu, Qiumei; Liu, Kaiyu; Liu, Hongtao

    2015-10-01

    Highly ordered TiO2 nanotube arrays (NTAs) with excellent stability and large specific surface area make them competitive using as supercapacitor materials. Improving the conductivity of TiO2 is of great concern for the construction of high-performance supercapacitors. In this work, we developed a novel approach to improve the performance of TiO2 materials, involving the fabrication of Al-doped TiO2 NTAs by a simple electrochemical cathodic polarization treatment in AlCl3 aqueous solution. The prepared Al-doped TiO2 NTAs exhibited excellent electrochemical performances, attributing to the remarkably improved electrical conductivity (i.e., from approx. 10 kΩ to 20 Ω). Further analysis showed that Al3+ ions rather than H+ protons doped into TiO2 lattice cause this high conductivity. A MnO2/Al-TiO2 composite was evaluated by cyclic voltammetry, and achieved the specific capacitance of 544 F g-1, and the Ragone plot of the sample showed a high power density but less reduction of energy density. These results indicate that the MnO2/Al-TiO2 NTAs sample could be served as a promising electrode material for high -performance supercapacitors.

  17. TiO2 nanotube-supported cu as the catalyst for selective NO reduction with NH3.

    PubMed

    Chen, Shin-An; Nian, Jun-Nan; Tsai, Chien-Cheng; Teng, Hsisheng

    2007-05-01

    Catalyst supports composed of titanate nanotubes were prepared from hydrothermal treatment on TiO2 nanoparticles in NaOH followed by HCl washing. The nanotubes exhibited well-defined TiO2 anatase phase after calcination at 400 degrees C. The nanotube aggregates and other commercially available TiO2 nanoparticles, all with surface areas >300 m(2)/g, were impregnated with Cu and examined in selective catalytic reduction of NO with NH3. In catalyst preparation, the nanotubes were found to be more thermally stable than nanoparticles, withstanding agglomeration at elevated temperatures. The Cu species supported on the nanotubes showed a higher catalytic activity than those supported on the nanoparticles. Analysis with temperature programmed reduction, X-ray photoelectron spectroscopy, and NO adsorption reflected that the layered-titanate feature of the tube wall was advantageous for even distribution of the Cu species, thus leading to the high-catalytic activity of the tubular Cu/TiO2 catalyst.

  18. Synthesis of TiO2 nanotube array thin films and determination of the optical constants using transmittance data

    NASA Astrophysics Data System (ADS)

    Ahmadi, K.; Abdolahzadeh Ziabari, Ali; Mirabbaszadeh, K.; Ahmadi, S.

    2015-01-01

    TiO2 nanotube arrays were grown on glass substrate by ZnO nanorod sol-gel template process. XRD analysis and FESEM microscopy were employed to characterize the structural and morphological properties of the prepared nanotube. EDX and UV-Vis spectroscopy were used to assess the chemical composition and study the optical properties of the film. An optical model has been performed to simulate the optical constants and thicknesses of the films from transmittance data using the Levenberg-Marquardt algorithm via Drude model. The simulated transmittance is in good agreement with the measured spectrum in the whole measurement wavelength range. The refractive index and extinction coefficient, thickness and dielectric function of TiO2 nanotube films were calculated by Drude model. Also, the related absorption coefficient, optical bandgap and porosity were determined.

  19. Influence of crystallite size and surface morphology on electrochemical properties of annealed TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Munirathinam, Balakrishnan; Pydimukkala, Haveela; Ramaswamy, Narayanan; Neelakantan, Lakshman

    2015-11-01

    The current study investigates the effect of crystallite size and surface morphology of TiO2 nanotubes on their wettability and electrochemical properties. Self-organized amorphous TiO2 nanotubes were synthesized by anodization process in an acidic (0.5 wt% HF) and a neutral electrolyte (1 M Na2SO4 + 0.5 wt% NaF). Subsequently, the nanotubes were annealed at 450 °C to achieve crystalline phase. Scanning electron microscope micrographs revealed that nanotubes formed from the neutral bath are four times longer (1.2 μm) than the ones synthesized from the acidic bath (325 nm). The charge consumed during anodization is greater under the acidic conditions implying the severity of the attack on the nanotubes by the electrolyte. X-Ray diffraction analysis showed that after annealing TiO2 crystallizes in the tetragonal lattice as anatase structure. Peak fitting method for line profile analysis was employed to estimate the crystallite size and the micro strain. The oxide nanotubes formed in neutral medium showed smaller crystallite size (28.91 nm) than the one formed in acidic medium (43.37 nm). Wettability measurements showed wetting angles <60°, indicating hydrophilic nature of the anatase nanotubes. Further, both the dimensional aspect (i.e., length and diameter of nanotubes) and the crystallite size have significant effect on the hydrophilic behavior. Electrochemical impedance spectroscopy in a simulated body fluid environment confirmed that structural changes in the oxide layer influence the electrochemical properties. Polarization studies demonstrated that crystallite size affects the passive behavior of the nanotubes. Smaller crystallite size (28.91 nm) lowers the passive current density (0.11 μA cm-2), indicating the good protectiveness.

  20. Morphological studies of vertical arrays TiO2 nanotubes by electrochemical anodization technique for dye sensitized solar cell application

    NASA Astrophysics Data System (ADS)

    Su'ait, M. S.; Alamgir, F.; Scardi, P.; Ahmad, A.

    2013-11-01

    A vertical array titanium dioxide nanotube (n-TiO2) for photovoltaic materials in dye sensitized solar cell has been synthesized by electrochemical anodization technique in NH4F aqueous solution. The morphological observation performed by SEM analysis on the scratch film showed that the distribution growths of TiO2 nanotubes on Ti subtract were uniform. The duration of growth is varied up to 12 h, with tubes length approximately 1 μm. However, at the maximum duration, a compact TiO2 layers were formed. This phenomenon is due to the field-assisted anodic oxidation at the interfaces of Ti/TiO2 is at equal rate with the field-assisted dissolution rate of the top TiO2 nanotube's surface, resulting from the decreased quantity of F- ions to form fluoro complexes, [TiF6]2-. A slight increase in the rate of the chemical dissolution reaction produced a precipitated TiO2. Hence, [TiF6]2- complexes which are required for tubes formation are difficult to exist.

  1. Preparation of TiO2 Nanotubes Loaded on Polyurethane Membrane and Research on Their Photocatalytic Properties.

    PubMed

    Lin, Longli; Wu, Qijun; Gong, Xun; Zhang, Yu

    2017-01-01

    To solve the problem of separation and recovery of photocatalyst in water, the modification of TiO2 was studied as well as its immobilization and photocatalytic properties. To improve surface properties, TiO2 nanotubes were synthesized by a hydrothermal method and silylated by silane coupling agents to introduce a certain functional group. Supported on polyurethane (PU) membrane, TiO2 nanotubes were prepared to produce immobilized PU/TiO2. Catalysts were characterized and identified by means of Fourier-transform infrared spectroscopy (FTIR), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), and scanning electron microscopy (SEM). Results showed that silylated TiO2 nanotubes were well grafted on the surface of the activated PU membrane. With a 300 W high pressure mercury lamp as light source, the photocatalytic activity and stability of immobilized PU/TiO2 were investigated with degrading methyl orange. It was showed that the target is degraded by immobilized PU/TiO2 with high activation and the catalytic performance is stable for a long time if catalyst is washed with ethanol.

  2. Preparation of TiO2 Nanotubes Loaded on Polyurethane Membrane and Research on Their Photocatalytic Properties

    PubMed Central

    Wu, Qijun; Zhang, Yu

    2017-01-01

    To solve the problem of separation and recovery of photocatalyst in water, the modification of TiO2 was studied as well as its immobilization and photocatalytic properties. To improve surface properties, TiO2 nanotubes were synthesized by a hydrothermal method and silylated by silane coupling agents to introduce a certain functional group. Supported on polyurethane (PU) membrane, TiO2 nanotubes were prepared to produce immobilized PU/TiO2. Catalysts were characterized and identified by means of Fourier-transform infrared spectroscopy (FTIR), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), and scanning electron microscopy (SEM). Results showed that silylated TiO2 nanotubes were well grafted on the surface of the activated PU membrane. With a 300 W high pressure mercury lamp as light source, the photocatalytic activity and stability of immobilized PU/TiO2 were investigated with degrading methyl orange. It was showed that the target is degraded by immobilized PU/TiO2 with high activation and the catalytic performance is stable for a long time if catalyst is washed with ethanol. PMID:28194295

  3. Orthodontic tunnel miniscrews with and without TiO2 nanotube arrays as a drug-delivery system: In vivo study.

    PubMed

    Cha, Bong-Kuen; Choi, Dong-Soon; Jang, Insan; Choe, Byung-Hak; Choi, Won-Youl

    2016-09-28

    Orthodontic tunnel miniscrews with and without TiO2 nanotube arrays were fabricated to improve the induction of new bone formation and osseointegration. To inject the drug of recombinant human bone morphogenetic protein, tunnels in a conventional machined miniscrew were machined by a computer-numerical-control lathe. TiO2 nanotube arrays to load the drug were also formed on the surface of the tunnel miniscrew by anodic oxidation. To obtain clean TiO2 nanotube arrays, two-step anodic oxidation was conducted. The diameters of TiO2 nanotube window and TiO2 nanotube were ∼70 nm and ∼110 nm, respectively. Three groups, i.e., a conventional machined miniscrew, a tunnel miniscrew without TiO2 nanotube arrays, and a tunnel miniscrew with TiO2 nanotube arrays, were prepared and inserted in the legs of five New Zealand White rabbits. In a histomorphometric analysis, the bone implant contact ratios of the tunnel miniscrews with the TiO2 nanotube arrays and without the TiO2 nanotube arrays were 5.84% and 5.88%, respectively. These values were higher than the value of 4.30% for the conventional machined miniscrew. The bone surface ratios in the tunnel miniscrew with and without the TiO2 nanotube were also higher than those of the conventional machined miniscrew. The measured values of the tunnel miniscrew with and without the nanotube and the conventional miniscrew were 76.75%, 73.41%, and 44.82%, respectively, although the differences were statistically insignificant. New bone at three weeks and six weeks after the operations were found in the tunnel miniscrews in fluorescent images. Both the tunnel miniscrews with and without the TiO2 nanotube arrays demonstrated greater bone formation compared to the conventional miniscrews. However, TiO2 nanotube arrays was not likely to provide additional benefit to the tunnel miniscrew. An in vivo study suggested that the tunnel fabricated in the miniscrew can be efficient drug-delivery systems to improve osseointegration.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Selective strain incorporation and retention into Si-substrate through VLS growth of TiO2 nano-islands

    NASA Astrophysics Data System (ADS)

    Palit, Mainak; Nag Chowdhury, Basudev; Das, Avishek; Das, Souvik; Chattopadhyay, Sanatan

    2017-02-01

    In this work, process induced strain has been incorporated selectively into Si-substrate by growing TiO2 nano-islands on it using vapour–liquid–solid method and the induced strain has been retained by chemically removing the TiO2 nano-islands. The retained strain is quantified by employing pole study method of the electron backscatter diffraction (EBSD) and compared with the similar results obtained from micro-Raman measurements. A very good agreement between the results indicates accuracy of the developed pole study analyses. Both the methods suggest that such a low-cost approach is capable of incorporating and retaining a compressive strain  >4.7% along < \\text{1} 0 0> and tensile strain  >1.3% along < 0 \\text{1} 0> and < 0 0 \\text{1}> directions by growing the crystalline TiO2 nano-islands on Si substrates followed by their chemical removal.

  6. Room temperature ferromagnetism in Co-incorporated TiO2 thin films.

    PubMed

    Sharma, Sudesh; Chaudhary, Sujeet; Panwar, N; Kashyap, Subhash C; Pandya, D K

    2011-03-01

    Observation of room temperature ferromagnetism (RTFM) in nano-crystalline Co-incorporated titanium dioxide [Ti(1-x)Co(x)O2(x = 0.05)] thin films prepared by spray pyrolysis technique is reported. While only the anatase phase was detected in as-deposited 5 at.% Co-incorporated TiO2 film, a small amount of rutile phase developed following its vacuum annealing. Besides, no X-ray diffraction peak corresponding to cobalt metal could be detected in any of the two films. SQUID magnetometry of both pristine and Co-doped thin films at room temperature elucidated distinct ferromagnetic behavior in 5 at.% Co-incorporated as-deposited film with saturation moment M(s) approximately 5.6 emu/cm3 which got enhanced up to 11.8 emu/cm3 on subsequent vacuum annealing. From the zero field cooled magnetization measurement we confirmed the absence of Co-metal clusters. The electrical resistivity was found to be greater than 108 omega-cm for the films. Based on the magnetic and electrical measurements the origin of RTFM has been attributed to the bound magnetic polaron (BMP) model.

  7. Highly efficient photoelectrocatalytic removal of RhB and Cr(VI) by Cu nanoparticles sensitized TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Zhong, J. S.; Wang, Q. Y.; Zhou, J.; Chen, D. Q.; Ji, Z. G.

    2016-03-01

    TiO2 nanotube arrays sensitized by copper nanoparticles (TiO2 NTs/Cu) exhibited highly efficient photoelectrocatalytic removal of RhB and Cr(VI). Vertically grown anatase TiO2 NTs on Ti substrates were prepared by electrochemical anodization followed by calcinations. Subsequently, Cu nanoparticles with uniform spherical structures and size distributions were deposited on TiO2 nanotubes by a modified hydrothermal reaction. By exploiting TiO2 NTs/Cu as both photoelectrodes and photocatalysts, high photocurrent density and photoelectrocatalytic removal efficiencies of RhB and Cr(VI) were achieved under solar light irradiation. The enhancement on the photoelectrochemical performance was explained by the optoelectronic coupling between Cu nanoparticles and TiO2 NTs, which accelerated the transfer rate of electrons, and subsequently decreased the electron/hole pair recombination.

  8. Preparation and Solar Light Photocatalytic Activity of N-Doped TiO2-Loaded Halloysite Nanotubes Nanocomposites

    NASA Astrophysics Data System (ADS)

    Cheng, Zhi-Lin; Sun, Wei

    2015-10-01

    A novel method to prepare N-doped TiO2-loaded halloysite nanotubes (N-TiO2/HNTs) nanocomposites was achieved by using the chemical vapor deposition in autoclave. The N-TiO2/HNTs nanocomposites obtained by the different form of the doping N source were studied through a series of characterizations. The XRD, SEM, and TEM characterizations verified the anatase structure of TiO2 nanoparticles with the size of ca.20nm loaded on the outer surface of HNTs. The UV-vis characterization of the N-TiO2/HNTs presented a further red-shift compared to the pure N-TiO2 nanoparticles.. The XPS characterizations confirmed the N element doped into the crystal structure of TiO2 nanoparticles. The photocatalytic activities of N-TiO2/HNTs nanocomposites prepared were evaluated by degradation of phenol at room temperature under simulated solar light irradiation.

  9. Effect of heat treatment on morphology, crystalline structure and photocatalysis properties of TiO 2 nanotubes on Ti substrate and freestanding membrane

    NASA Astrophysics Data System (ADS)

    Fang, Dong; Luo, Zhiping; Huang, Kelong; Lagoudas, Dimitris C.

    2011-05-01

    Highly ordered titanium oxide (TiO 2) nanotubes were prepared by electrolytic anodization of titanium electrodes. Morphological evolution and phase transformations of TiO 2 nanotubes on a Ti substrate and that of freestanding TiO 2 membranes during the calcinations process were studied by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction microscopy. The detailed results and mechanisms on the morphology and crystalline structure were presented. Our results show that a compact layer exists between the tubular layer and Ti substrate at 600 °C, and the length of the nanotubes shortens dramatically at 750 °C. The freestanding membranes have many particles on their tubes during calcinations from 450 to 900 °C. The TiO 2 nanotubes on the Ti substrate transform to rutile crystals at 600 °C, while the freestanding TiO 2 membranes retain an anatase crystal with increasing temperature to 800 °C. The photocatalytic activity of TiO 2 nanotubes on a Ti substrate annealed at different temperatures was investigated by the degradation of methyl orange in aqueous solution under UV light irradiation. Due to the anatase crystals in the tubular layer and rutile crystals in the compact layer, TiO 2 nanotubes annealed at 450 °C with pure anatase crystals have a better photocatalytic activity than those annealed at 600 °C or 750 °C.

  10. Preparation of TiO2 nanotube/nanoparticle composite particles and their applications in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Lee, Chang Hyo; Rhee, Seung Woo; Choi, Hyung Wook

    2012-01-01

    Efficiency of dye-sensitized solar cells [DSSCs] was enhanced by combining the use of TiO2 nanotubes [TNTs] and nanoparticles. TNTs were fabricated by a sol-gel method, and TiO2 powders were produced through an alkali hydrothermal transformation. DSSCs were constructed using TNTs and TiO2 nanoparticles at various weight percentages. TNTs and TiO2 nanoparticles were coated onto FTO glass by the screen printing method. The DSSCs were fabricated using ruthenium(II) (N-719) and electrolyte (I3/I3 -) dyes. The crystalline structure and morphology were characterized by X-ray diffraction and using a scanning electron microscope. The absorption spectra were measured using an UV-Vis spectrometer. The incident photocurrent conversion efficiency was measured using a solar simulator (100 mW/cm2). The DSSCs based on TNT/TiO2 nanoparticle hybrids showed better photovoltaic performance than cells made purely of TiO2 nanoparticles.

  11. Preparation of TiO2 nanotube/nanoparticle composite particles and their applications in dye-sensitized solar cells.

    PubMed

    Lee, Chang Hyo; Rhee, Seung Woo; Choi, Hyung Wook

    2012-01-05

    Efficiency of dye-sensitized solar cells [DSSCs] was enhanced by combining the use of TiO2 nanotubes [TNTs] and nanoparticles. TNTs were fabricated by a sol-gel method, and TiO2 powders were produced through an alkali hydrothermal transformation. DSSCs were constructed using TNTs and TiO2 nanoparticles at various weight percentages. TNTs and TiO2 nanoparticles were coated onto FTO glass by the screen printing method. The DSSCs were fabricated using ruthenium(II) (N-719) and electrolyte (I3/I3-) dyes. The crystalline structure and morphology were characterized by X-ray diffraction and using a scanning electron microscope. The absorption spectra were measured using an UV-Vis spectrometer. The incident photocurrent conversion efficiency was measured using a solar simulator (100 mW/cm2). The DSSCs based on TNT/TiO2 nanoparticle hybrids showed better photovoltaic performance than cells made purely of TiO2 nanoparticles.

  12. Sonochemical Degradation of Reactive Black 5 with a Composite Catalyst of TiO2/Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Cho, Eunju; Choi, Jongbok; Lee, Yonghyeon; Park, Jeong Min; Khim, Jeehyeong

    2013-07-01

    In the sonocatalytic process, composites of TiO2-carbon were used because carbon provides more adsorption sites and acts like an electron sink to prevent the recombination of an electron/hole. Therefore, in the present study, the characteristics of a TiO2/single-walled carbon nanotubes catalyst (TiO2/SWCNTs) have been investigated, and the optimal weight ratio of SWCNTs and the dose for degradation of reactive black 5 (RB5) were also evaluated. TiO2/SWCNT composite was characterized using Brunauer-Emmett-Teller analysis, scanning electron microscopy, energy-dispersive X-ray diffraction microanalysis and spectra, and X-ray diffraction patterns. The degradation rate constants of RB5 with the ratio of SWCNTs were found to depend on the adsorption phenomenon of a surface catalyst, light absorbance, and the recombination of electrons and holes. As a result, the optimal ratio of carbon in the sono-TiO2/SWCNTs process for degradation of RB5 was TiO2:SWCNTs= 200:1. Additionally, the optimal dose of the catalyst was 0.5 g/L.

  13. Preparation of TiO2 nanotube/nanoparticle composite particles and their applications in dye-sensitized solar cells

    PubMed Central

    2012-01-01

    Efficiency of dye-sensitized solar cells [DSSCs] was enhanced by combining the use of TiO2 nanotubes [TNTs] and nanoparticles. TNTs were fabricated by a sol-gel method, and TiO2 powders were produced through an alkali hydrothermal transformation. DSSCs were constructed using TNTs and TiO2 nanoparticles at various weight percentages. TNTs and TiO2 nanoparticles were coated onto FTO glass by the screen printing method. The DSSCs were fabricated using ruthenium(II) (N-719) and electrolyte (I3/I3-) dyes. The crystalline structure and morphology were characterized by X-ray diffraction and using a scanning electron microscope. The absorption spectra were measured using an UV-Vis spectrometer. The incident photocurrent conversion efficiency was measured using a solar simulator (100 mW/cm2). The DSSCs based on TNT/TiO2 nanoparticle hybrids showed better photovoltaic performance than cells made purely of TiO2 nanoparticles. PMID:22222095

  14. Direct formation of anatase TiO2 nanoparticles on carbon nanotubes by atomic layer deposition and their photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Huang, Sheng-Hsin; Liao, Shih-Yun; Wang, Chih-Chieh; Kei, Chi-Chung; Gan, Jon-Yiew; Perng, Tsong-Pyng

    2016-10-01

    TiO2 with different morphology was deposited on acid-treated multi-walled carbon nanotubes (CNTs) by atomic layer deposition at 100 °C-300 °C to form a TiO2@CNT structure. The TiO2 fabricated at 100 °C was an amorphous film, but became crystalline anatase nanoparticles when fabricated at 200 °C and 300 °C. The saturation growth rates of TiO2 nanoparticles at 300 °C were about 1.5 and 0.4 Å/cycle for substrate-enhanced growth and linear growth processes, respectively. It was found that the rate constants for methylene blue degradation by the TiO2@CNT structure formed at 300 °C were more suitable to fit with second-order reaction. The size of 9 nm exhibited the best degradation efficiency, because of the high specific area and appropriate diffusion length for the electrons and holes.

  15. Elaboration and characterization of TiO2 nanoparticles incorporated in SiO2 host matrix

    NASA Astrophysics Data System (ADS)

    Amlouk, A.; El Mir, L.; Kraiem, S.; Alaya, S.

    2006-07-01

    Nanometer-scale TiO2 particles have been synthesized by sol gel method. It was incorporated in a glass-based silica aerogel. The composite was characterized by various techniques such as particle size analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray diffraction (XRD), infrared spectroscopy (IR) and photoluminescence (PL). The bulk glass presents a strong luminescence at wavelengths ranging from 750 to 950 nm. This PL was attributed to various non-bridging oxygen hole centers (NBOHCs) defects resulting from thermal treatment and crystallization of TiO2 at the interface between titania nanoparticles and silica host matrix.

  16. The function of a TiO2 compact layer in dye-sensitized solar cells incorporating "planar" organic dyes.

    PubMed

    Burke, Anthony; Ito, Seigo; Snaith, Henry; Bach, Udo; Kwiatkowski, Joe; Grätzel, Michael

    2008-04-01

    We present a device based study into the operation of liquid electrolyte dye-sensitized solar cells (DSSC's) using organic dyes. We find that, for these systems, it is entirely necessary to employ a compact TiO2 layer between the transparent fluorine doped SnO2 (FTO) anode and the electrolyte in order to reduce charge recombination losses. By incorporation of a compact layer, the device efficiency can be increased by over 160% under simulated full sun illumination and more than doubled at lower light intensities. This is strong evidence that the more widely employed ruthenium based sensitizers act as to "insulate" the anode against recombination losses and that many planar organic dyes employed in DSSC's could greatly benefit from the use of a compact TiO2 blocking layer. This is in strong contrast to DSSC's sensitized with ruthenium based systems, where the introduction of compact TiO2 has only marginal effects on conversion efficiencies.

  17. Bioactivity of self-organized TiO2 nanotubes used as surface treatment on Ti biomaterials

    NASA Astrophysics Data System (ADS)

    Souza, M. R.; Reyes, K. M.; Oliveira, N. T. C.; Kuromoto, N. K.; Marino, C. E. B.

    2016-03-01

    Titanium and its alloys are widely used as implants due to their excellent mechanical properties, corrosion resistance and biocompatibility. TiO2 nanotubes have been studied as surface treatment to increase the specific area and to improve osseointegration. However, the thermodynamic stability and bioactivity of these nanostructures must be evaluated. The objective of this research was to obtain nanotubes oxides on Ti6Al4V alloy and to analyze the electrochemical stability in physiological solution at 37 °C and the bioactive response of the biomaterial. The nanotubes were obtained by potentiostatic anodization. The morphology of the oxides was evaluated by scanning electron microscopy. The chemical characterization was analyzed by energy dispersive spectroscopy and x-ray photoelectron spectroscopy techniques. The electrochemical stability was analyzed by open circuit potential (OCP) and the bioactivity by biomimetic test in a simulated body fluid (SBF) solution. The OCP of the nanotubes oxides was shown to be more noble and stable than the compacted oxides. The biomaterial covered with theses oxides showed sealing by Ca and P after 30 d immersion in artificial blood. And after 15 d of immersion in SBF, the hydroxyapatite could be seen on the non-sealed nanotubes. TiO2 nanotube layers could improve the superficial chemical stability and also the osseointegration process.

  18. Highly sensitive chemiluminescence immunoassay on chitosan membrane modified paper platform using TiO2 nanoparticles/multiwalled carbon nanotubes as label.

    PubMed

    Li, Weiping; Ge, Shenguang; Wang, Shoumei; Yan, Mei; Ge, Lei; Yu, Jinghua

    2013-01-01

    A highly sensitive chemiluminescence (CL) immunoassay was incorporated into a low-cost microfluidic paper-based analytical device (μ-PAD) to fabricate a facile paper-based CL immunodevice (denoted as μ-PCLI). This μ-PCLI was constructed by covalently immobilizing capture antibody on a chitosan membrane modified μ-PADs, which was developed by simple wax printing methodology. TiO2 nanoparticles coated multiwalled carbon nanotubes (TiO2/MWCNTs) were synthesized as an amplification catalyst tag to label signal antibody (Ab2). After sandwich-type immunoreactions, the TiO2/MWCNTs were captured on the surface of μ-PADs to catalyze the luminol-p-iodophenol-H2O2 CL system, which produced an enhanced CL emission. Using prostate-specific antigen as a model analyte, the approach provided a good linear response range from 0.001 to 20 ng/mL with a low detection limit of 0.8 pg/mL under optimal conditions. This μ-PCLI showed good reproducibility, selectivity and stability. The assay results of prostate-specific antigen in clinical serum samples were in good agreement with that obtained by commercially used electrochemiluminescence methods at the Cancer Research Center of Shandong Tumor Hospital (Jinan, Shandong Province, China). This μ-PCLI could be very useful to realize highly sensitive, qualitative point-of-care testing in developing or developed countries.

  19. Carbon Single Walled Nanotubes- Electron Acceptor Molecules for Improving the Efficiency of the Photoexcitation of TiO2 for Solar-Driven Technologies

    DTIC Science & Technology

    2012-10-16

    Single walled nanotubes ( SWNTs ) are shown to be electron acceptor molecules. The PL was used to observe the buildup during UV irradiation of surface...surface. Single walled nanotubes ( SWNTs ) are shown to be electron acceptor molecules. The PL was used to observe the buildup during UV irradiation of...the TiO2 bed and through the bed containing SWNT linkers. It was found that while SWNTs are good acceptors, no added conductivity from isolated TiO2

  20. Anatase TiO2 nanotube powder film with high crystallinity for enhanced photocatalytic performance

    NASA Astrophysics Data System (ADS)

    Lin, Jia; Liu, Xiaolin; Zhu, Shu; Liu, Yongsheng; Chen, Xianfeng

    2015-03-01

    We report on the synthesis of TiO2 nanotube (NT) powders using anodic oxidation and ultrasonication. Compared to free-standing NT array films, the powder-type NTs can be easily fabricated in a cost-effective way. Particularly, without the substrate effect arising from underlying Ti metals, highly crystallized NT powders with intact tube structures and pure anatase phase can be obtained using high-temperature heat treatment. The application of NTs with different crystallinity for the photocatalytic decomposition of methylene blue (MB) was then demonstrated. The results showed that with increasing annealing temperature, the photocatalytic decomposition rate was gradually enhanced, and the NT powder electrode annealed at 650°C showed the highest photoactivity. Compared to typical NTs annealed at 450°C, the rate constant increased by 2.7-fold, although the surface area was 21% lower. These findings indicate that the better photocatalytic activity was due to the significantly improved crystallinity of anatase anodic NTs in powder form, resulting in a low density of crystalline defects. This simple and efficient approach is applicable for scaled-up water purification and other light utilization applications.

  1. TiO2 nanotubes supported NiW hydrodesulphurization catalysts: Characterization and activity

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    High surface area TiO2 nanotubes (Ti-NT) synthesized by alkali hydrothermal method were used as a support for NiW hydrodesulphurization catalyst. Nickel salt of 12-tungstophosphoric acid - Ni3/2PW12O40 was applied as oxide precursor of the active components. The catalyst was characterized by SBET, 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.

  2. Capture of carbon dioxide from flue gases by amine-functionalized TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Song, Fujiao; Zhao, Yunxia; Cao, Yan; Ding, Jie; Bu, Yunfei; Zhong, Qin

    2013-03-01

    The novel carbon dioxide (CO2) adsorbents with high capture efficiency were prepared through impregnating TiO2 nanotubes (TiNT) with four kinds of amines, namely monoethanolamine (MEA), ethylenediamine (EDA), triethylenetetramine (TETA) and tetraethylenepentamine (TEPA), respectively. The samples were characterized by thermogravimetric analysis, low temperature N2 adsorption and transmission electron microscopy. CO2 capture was investigated in a dynamic packed column. The TEPA-loaded sample showed a better adsorption capacity due to its higher amino-groups content. In condition, TiNT-TEPA-69 shows the highest CO2 adsorption capacity among the four TEPA-loaded samples, approximately 4.37 mmol/g at 60 °C. The adsorption capacity was enhanced to 5.24 mmol/g under moisture conditions. TiNT-TEPA-69 was selected as adsorbent to study the adsorption/desorption behavior in the absence of moisture and in the presence of moisture. While the former is fairly stable after 5 adsorption/desorption cycles, the latter decreases dramatically.

  3. On the biocompatibility between TiO2 nanotubes layer and human osteoblasts.

    PubMed

    Portan, Diana V; Kroustalli, Anthi A; Deligianni, Despina D; Papanicolaou, George C

    2012-10-01

    Titanium and its alloys are the most popular biomaterials replacing hard tissues in implant surgeries. Clinicians are generally pleased by titanium mechanical properties and non-toxicity performances; on the other hand, there have been reported several cases of titanium implantation failure, phenomenon explained sometimes as "non adherence of human tissue to the metallic surface." Yet, researchers reported that titanium surfaces are favorable for osteoblasts adhesion. Therefore, titanium integration into the human body remains an unsolved problem. In the present study, biocompatibility tests were performed on titanium and TiO(2) nanotubes substrates, involving human bone marrow cells. The combination of a newly developed analytical model based on the hybrid interphase concept, applicable to systems consisting of inert materials when in contact with living tissues, together with experimental results, confirmed previous research studies and lead to the conclusion that osteoblasts adhere efficiently to titanium surfaces. However, the present results suggest that osteoblasts strong anchorage at the very first moment of their contact with the metallic material leads to their apoptosis. It is most probable that in several cases this is the reason of failed implantation surgeries involving titanium.

  4. Synthesis and photo-catalytic property of TiO2 nanotube arrays/ZnS

    NASA Astrophysics Data System (ADS)

    Kong, Junhan; Liu, Zhe; Xiong, Yehan; Liu, Zhanhong; Wang, Yongqian

    2017-04-01

    TiO2 nanotube arrays/ZnS (TNAs/ZnS) nanocomposites were synthesized successfully via anodic oxidation method and hydrothermal method as well. In this study, field emission scanning electron microscopy equipped with energy-dispersive spectroscopy (EDS) was used to monitor the morphological features and elemental composition of the samples. UV-Vis absorption spectra showed the absorption performance in both UV and visible light regions. In addition, the photo-catalytic activity of the samples was measured by the photo-degradation rate of methylene blue. From the result, we could notice that the morphology of the samples would change gradually when the amounts of zinc source and sulfur source changed, and the hydrothermal temperature was one of the significant factors which influenced the morphology. EDS spectra showed the existence of zinc and sulfur elements. Photo-catalytic activity test indicated that the photo-degradation rate of MB rises up to 91.6% after 240 min. Furthermore, there existed an expected relationship between the photo-degradation rate and the amounts of zinc source and sulfur source. UV-Vis absorption spectra of the samples also verified the result of photo-catalytic activity test.

  5. Capture of carbon dioxide by amine-loaded as-synthesized TiO2 nanotubes.

    PubMed

    Song, Fujiao; Zhao, Yunxia; Ding, Huiling; Cao, Yan; Ding, Jie; Bu, Yunfei; Zhong, Qin

    2013-01-01

    Titanium-based adsorbents for CO2 capture were prepared through impregnating the as-synthesized TiO2 nanotubes (TiNT) with four kinds of amines, namely monoethanolamine (MEA), ethylenediamine (EDA), triethylenetetramine (TETA) and tetraethylenepentamine (TEPA). The resultant samples were characterized by X-ray diffraction, low-temperature N2 adsorption as well as transmission electron microscopy. The absorption of CO2 was carried out in a dynamic packed column. The sample impregnated with TEPA showed a better adsorption capacity due to its higher amino groups content. In addition, CO2 adsorption capacity increases as the amount of amine loaded increases. Therefore, TiNT-TEPA-69 showed the highest CO2 adsorption capacity among the three samples impregnated with TETA; approximately 4.10 mmol/g at 30 degrees C. In addition, the dynamic adsorption/desorption performance was investigated. The adsorption capacity of TiNT-TEPA-69 dropped slightly (about 2%) during a total of five cycles. The TiNT-TEPA-69 adsorbent exhibited excellent CO2 adsorption/desorption performance.

  6. Design and evaluation of a UV LED Photocatalytic Reactor Using Anodized TiO2 Nanotubes.

    PubMed

    Ghosh, Jyoti P; Achari, Gopal; Langford, Cooper H

    2016-08-01

    A bench-scale flow-through photocatalytic reactor using light emitting diodes (LED) as light source and a TiO2 nanotube array (TN) as immobilized catalyst has been designed, fabricated and tested on commonly studied contaminants. The photoreactor is comprised of 144, 365-nm UV-LED lamps mounted along the inner periphery of an annular cylinder. An ordered array of TN, as catalyst, was immobilized by electrochemical anodization of a titanium cylinder and placed in the center of the reactor. Synthesized TN was characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Laboratory investigations were conducted on the photoreactor to treat 4-chlorophenol (4-CP), atrazine and methylene blue. The performance of the photoreactor at different flow rates and at varying distances of photocatalyst from the light source was monitored. The photocatalytic reaction rates increased with bubbling oxygen into the reservoir. Significant improvement was observed when H2O2 was added and degradation to detection limits was observed.

  7. Nitrogen doped TiO2 nanotube arrays with high photoelectrochemical activity for photocatalytic applications

    NASA Astrophysics Data System (ADS)

    Yuan, Bao; Wang, Yan; Bian, Haidong; Shen, Tiankuo; Wu, Yucheng; Chen, Zhong

    2013-09-01

    Nitrogen doped TiO2 nanotube arrays (N-TNAs) were prepared by immersing TNAs in 1 M NH3·H2O solution and then annealing in different temperatures. The morphology, structure and composition of the N-TNAs were characterized by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy, respectively. Effects of annealing temperatures on structure, photocatalytic properties, and the crystal structure transformation process of the N-TNAs were discussed. Photocatalytic properties of the N-TNAs were evaluated in term of the degradation of methyl orange (MO) under UV light and visible light, and the photocurrent of N-TNAs were tested by electrochemical workstation. The XPS results showed that the N-TNAs were achieved by interstitial doping and substitutional doping, and the FESEM results showed the morphology was not changed after doping process. Compared with the pure TNAs, the N-TNAs annealed at 500 ̊C for 2 h with a mixed phase of anatase and rutile exhibited higher photocatalytic degradation activity to MO. Furthermore, the photocatalytic mechanism of organic pollutants degradation (MO) was discussed based on our experiments.

  8. Visible light-harvesting of TiO2 nanotubes array by pulsed laser deposited CdS

    NASA Astrophysics Data System (ADS)

    Bjelajac, Andjelika; Djokic, Veljko; Petrovic, Rada; Socol, Gabiel; Mihailescu, Ion N.; Florea, Ileana; Ersen, Ovidiu; Janackovic, Djordje

    2014-08-01

    Titanium dioxide (TiO2) nanotubes arrays, obtained by anodization technique and annealing, were decorated with CdS using pulsed laser deposition method. Their structural, morphological and chemical characterization was carried out by electron microscopy in scanning (SEM) and transmission (TEM) modes, combined with energy dispersive spectroscopy (EDS) and electron energy loss spectroscopy (EELS). It was demonstrated that the quantity of deposited CdS can be controlled by varying the number of laser pulses. The chemical mapping of the elements of interest was performed using the energy filtered mode of the electron microscope. The results showed that pulse laser deposition is an adequate technique for deposition of CdS inside and between 100 nm wide TiO2 nanotubes. The diffuse reflectance spectroscopy investigation of selected samples proved that the absorption edge of the prepared CdS/TiO2 nanocomposites is significantly extended to the visible range. The corresponding band gaps were determinated from the Tauc plot of transformed Kubelka-Munk function. The band gap reduction of TiO2 nanotubes by pulsed laser deposition of CdS was put in evidence.

  9. Fe3+-Doped TiO2 Nanotube Arrays on Ti-Fe Alloys for Enhanced Photoelectrocatalytic Activity

    PubMed Central

    Yu, Jiangdong; Wu, Zhi; Gong, Cheng; Xiao, Wang; Sun, Lan; Lin, Changjian

    2016-01-01

    Highly ordered, vertically oriented Fe3+-doped TiO2 nanotube arrays (Fe-TNTs) were prepared on Ti-Fe alloy substrates with different Fe contents by the electrochemical anodization method. The as-prepared Fe-TNTs were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and related electrochemical techniques. XPS results demonstrated that Fe3+ ions were successfully doped into TiO2 nanotubes. The photoelectrochemical activity of Fe-TNTs was compared with that of pure TiO2 nanotube arrays (TNTs). The results showed that Fe-TNTs grown on low concentration (0.5 wt %–1 wt % Fe) Ti-Fe alloys possessed higher photocurrent density than TNTs. The Fe-TNTs grown on Ti-Fe alloy containing 0.8 wt % Fe exhibited the highest photoelectrochemical activity and the photoelectrocatalytic degradation rate of methylene blue (MB) aqueous solution was significantly higher than that of TNTs. PMID:28335234

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

    NASA Astrophysics Data System (ADS)

    Tran, Vy Anh; Truong, Trieu Thinh; Phan, Thu Anh Pham; Nguyen, Trang Ngoc; Huynh, Tuan Van; Agresti, Antonio; Pescetelli, Sara; Le, Tien Khoa; Di Carlo, Aldo; Lund, Torben; Le, So-Nhu; Nguyen, Phuong Tuyet

    2017-03-01

    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 M NaOH. The nano-tubes were N-doped by reflux in various concentrations of NH4NO3. 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.

  11. Preparation and properties of a phthalocyanine-sensitized TiO2 nanotube array for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Cheng, Wanxi; Shen, Yue; Wu, Guizhi; Gu, Feng; Zhang, Jiancheng; Wang, Linjun

    2010-12-01

    Dye-sensitized solar cells (DSSCs) based on an ordered titanate nanotube (TNT) array were fabricated using phthalocyanine as a dye sensitizer. The ordered TNT photoanode was prepared via two steps: (1) electrosynthesis of the TiO2 nanotube array in the HF solution by the anodization method; (2) electrodeposition of 2,9,16,23-tetra-amino zinc phthalocyanine (TAZnPc) in the TiO2 nanotubes array. The morphological characteristics and structures of TAZnPc immobilized TiO2 NTs (TAZnPc/TiO2 NTs) were examined. The average pore diameter of the TNT structures was 100 nm and its average length was 500 nm. The diffuse reflection spectra (DRS) curves of TAZnPc/TiO2 NTs had a wide absorption at 550-950 nm, which may come from the TAZnPc. The photocurrent and photovoltage of the cells were measured with an active area of 0.25 cm2 by using CHI660B electrochemical workstation in the condition of illumination (AM 1.5, 100 mW cm-2). The open circuit voltage (Voc), short circuit current (Jsc) and fill factor (FF) of the DSSC are 0.416 V, 0.115 mA cm-2 and 0.68, respectively.

  12. Polypyrrole self-organized nanopore arrays formed by controlled electropolymerization in TiO2 nanotube template.

    PubMed

    Kowalski, Damian; Schmuki, Patrik

    2010-12-07

    A new concept for formation of nanostructured intrinsically conducting polymers (ICP) is demonstrated. Polypyrrole can be electropolymerized from an ionic-surfactant-solution in TiO(2) nanotube framework to form a geometrical structure of self-organized nanopore arrays. Polymerization is initialized selectively in the space between nanotube walls forming a mechanically stable polymer network with controlled wall thickness from 40 to 10 nm. Such robust polymer nanostructures are very promising for application in electrochemical systems of limited charge carrier diffusion length.

  13. Origin of the improved photocatalytic activity of Cu incorporated TiO2 for hydrogen generation from water

    NASA Astrophysics Data System (ADS)

    Hu, Qianqian; Huang, Jiquan; Li, Guojing; Jiang, Yabin; Lan, Hai; Guo, Wang; Cao, Yongge

    2016-09-01

    Cu incorporated TiO2 has been regarded as a low-cost photocatalyst with excellent photocatalytic performance for water splitting. Here we try to exploit the origin of its high reactivity by fabricating a series of Cu incorporated TiO2 films with the same Cu content under different atmosphere. Based on the comprehensive structure and surface characterizations, it is found that CuO is unstable and will be reduced to Cu2O or even to metallic Cu under light irradiation during the photocatalytic reaction, and Cu2O is an efficient co-catalyst that promotes the separation of photogenerated carriers while metallic Cu can further boost the photocatalytic activity. Besides, it is also noticed that the chemisorbed oxygen on the particle surface blocks the water splitting. By depositing TiO2 films under oxygen rich condition, oxygen vacancy is decreased greatly, which facilitates the removal of chemisorbed oxygen and the formation of metallic Cu during photocatalytic reaction, resulting in an ultra-high H2 evolution rate of 2.80 μmol cm-2 h-1, which is about 55 times higher than that of pure TiO2.

  14. Preparation, characterization and visible-light-driven photocatalytic activity of Fe-incorporated TiO2 microspheres photocatalysts

    NASA Astrophysics Data System (ADS)

    Li, Jun-Qi; Wang, De-Fang; Guo, Zhan-Yun; Zhu, Zhen-Feng

    2012-12-01

    Fe incorporated TiO2 microspheres (Fe-TiO2) were prepared by integrating the sol-gel method and impregnating-calcination method. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-vis diffuse reflectance spectroscopy indicated that α-Fe2O3 nanoparticles were deposited onto the TiO2 microspheres, and in the mean time, some Fe3+ ions were doped into TiO2 lattice. The absorption of Fe-TiO2 microspheres in the visible light region increased with the increasing of Fe content. Photoluminescence (PL) analyses further confirmed that Fe-incorporation effectively promoted the separation and transfer of photogenerated charge carriers, which can improve the photocatalytic activity of the samples. The photocatalytic activity of Fe-TiO2 microspheres was evaluated by the degradation of methylene blue aqueous solution under visible light irradiation. The results demonstrated that the Fe-TiO2 microspheres exhibited significantly enhanced photocatalytic activity compared with pure TiO2 microspheres. What is more, the charge-transfer processes in Fe-TiO2 were also discussed.

  15. Preparation of Pd-loaded La-doped TiO2 nanotubes and investigation of their photocatalytic activity under visible light

    NASA Astrophysics Data System (ADS)

    Zong, Lanlan; Li, Qiuye; Zhang, Jiwei; Wang, Xiaodong; Yang, Jianjun

    2013-11-01

    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 TiO2. However, in our former research, we found that calcination of TAN to anatase TiO2 would destroy the nanotubular structure and decrease the BET surface area sharply. In this work, we utilized the pillar effect of the foreign nanoparticles (La2O3) to keep the nanotubular morphology of TiO2, and obtained the anatase TiO2 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 TiO2 by photo-deposition method. The photocatalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, diffuse reflectance spectra, and N2 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 TiO2 nanotubes improved effectively compared with that of La-doped TiO2 and pure TiO2.

  16. Fabrication of single TiO2 nanotube devices with Pt interconnections using electron- and ion-beam-assisted deposition

    NASA Astrophysics Data System (ADS)

    Lee, Mingun; Cha, Dongkyu; Huang, Jie; Ha, Min-Woo; Kim, Jiyoung

    2016-06-01

    Device fabrication using nanostructured materials, such as nanotubes, requires appropriate metal interconnections between nanotubes and electrical probing pads. Here, electron-beam-assisted deposition (EBAD) and ion-beam-assisted deposition (IBAD) techniques for fabrication of Pt interconnections for single TiO2 nanotube devices are investigated. IBAD conditions were optimized to reduce the leakage current as a result of Pt spreading. The resistivity of the IBAD-Pt was about three orders of magnitude less than that of the EBAD-Pt, due to low carbon concentration and Ga doping, as indicated by X-ray photoelectron spectroscopy analysis. The total resistances of single TiO2 nanotube devices with EBAD- or IBAD-Pt interconnections were 3.82 × 1010 and 4.76 × 108 Ω, respectively. When the resistivity of a single nanotube is low, the high series resistance of EBAD-Pt cannot be ignored. IBAD is a suitable method for nanotechnology applications, such as photocatalysis and biosensors.

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

    PubMed

    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.

  18. Low-temperature synthesis of high-ordered anatase TiO2 nanotube array films coated with exposed {001} nanofacets

    PubMed Central

    Ding, Jie; Huang, Zhennan; Zhu, Jihao; Kou, Shengzhong; Zhang, Xiaobin; Yang, Hangsheng

    2015-01-01

    High-ordered anatase TiO2 nanotube array films coated with exposed high-reactive {001} nanofacets were fabricated by a modified hydrothermal method using amorphous anodic TiO2 nanotube arrays (ATONAs) as starting materials. It was found that the reaction between gas phase HF and solid ATONAs played a key role in the transformation process from amorphous to anatase TiO2, and the TiO2 tubular structure kept unchanged during the surface modification with an exposed {001} facets up to 76.5%, which could be attributed to the low reaction temperature of 130 °C. Our study provided a novel route for the facile preparation of {001} facets exposed anatase TiO2. PMID:26634815

  19. Atomic Layer Deposition Al2O3 Coatings Significantly Improve Thermal, Chemical, and Mechanical Stability of Anodic TiO2 Nanotube Layers

    PubMed Central

    2017-01-01

    We report on a very significant enhancement of the thermal, chemical, and mechanical stability of self-organized TiO2 nanotubes layers, provided by thin Al2O3 coatings of different thicknesses prepared by atomic layer deposition (ALD). TiO2 nanotube layers coated with Al2O3 coatings exhibit significantly improved thermal stability as illustrated by the preservation of the nanotubular structure upon annealing treatment at high temperatures (870 °C). In addition, a high anatase content is preserved in the nanotube layers against expectation of the total rutile conversion at such a high temperature. Hardness of the resulting nanotube layers is investigated by nanoindentation measurements and shows strongly improved values compared to uncoated counterparts. Finally, it is demonstrated that Al2O3 coatings guarantee unprecedented chemical stability of TiO2 nanotube layers in harsh environments of concentrated H3PO4 solutions. PMID:28291942

  20. Preparation and photovoltaic properties of layered TiO2/carbon nanotube/TiO2 photoanodes for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Barberio, M.; Grosso, D. R.; Imbrogno, A.; Xu, F.

    2016-03-01

    In this paper, we report on the realization of photoanodes for dye sensitized solar cells based on composites of carbon nanotubes and titanium dioxide nanoparticles. Our results show the best photovoltaics performance for carbon nanotubes weight percentages between 0.2% and 0.4%. Photoanodes realized in three-layer configuration, TiO2/carbon nanotube/TiO2, show a cell efficiency of 10.5% and a fill factor of 70%, values 2.4 times greater with respect to that of classical TiO2 anode. The presence of carbon nanotubes enhances the charge transport, strongly reducing the electron/hole recombination in the anode bulk, while the double layer of TiO2 increases the dye adsorption limiting the reduction caused by the presence of carbon nanotubes.

  1. Atomic Layer Deposition Al2O3 Coatings Significantly Improve Thermal, Chemical, and Mechanical Stability of Anodic TiO2 Nanotube Layers.

    PubMed

    Zazpe, Raul; Prikryl, Jan; Gärtnerova, Viera; Nechvilova, Katerina; Benes, Ludvik; Strizik, Lukas; Jäger, Ales; Bosund, Markus; Sopha, Hanna; Macak, Jan M

    2017-04-04

    We report on a very significant enhancement of the thermal, chemical, and mechanical stability of self-organized TiO2 nanotubes layers, provided by thin Al2O3 coatings of different thicknesses prepared by atomic layer deposition (ALD). TiO2 nanotube layers coated with Al2O3 coatings exhibit significantly improved thermal stability as illustrated by the preservation of the nanotubular structure upon annealing treatment at high temperatures (870 °C). In addition, a high anatase content is preserved in the nanotube layers against expectation of the total rutile conversion at such a high temperature. Hardness of the resulting nanotube layers is investigated by nanoindentation measurements and shows strongly improved values compared to uncoated counterparts. Finally, it is demonstrated that Al2O3 coatings guarantee unprecedented chemical stability of TiO2 nanotube layers in harsh environments of concentrated H3PO4 solutions.

  2. Preparation of Fe-doped TiO2 nanotube arrays and their room-temperature ferromagnetic properties.

    PubMed

    Wang, Jianli; Liu, Chao; Shen, Weidong; Cao, Chunlan; Song, Sihong

    2014-08-01

    Fe-doped titania nanotube arrays (NTs) were fabricated by electrochemical anodization on a Ti foil using Fe(NO3)3 · 2H2O as iron source. Their morphology, structure and optical properties were investigated by field emission scanning electron microscopy, X-ray diffraction, UV-visible absorption spectroscopy and photoluminescence spectroscopy. The UV-visible reflection spectrum of the Fe-doped TiO2 NTs showed a red shift in wavelength of absorption and greater reflectivity compared with the undoped sample due to the Fe ion incorportion in TiO2 lattices. The photoluminescence spectrum of the Fe-doped TiO2 NTs shows two strong new peaks centered at 388 nm and 694 nm, besides the UV emission peak owing to the electronic transition mediated by the defect levels such as oxygen vacancies in the band gap. The magnetic property of the Fe-doped TiO2 NTs exhibits a room temperature ferromagnetic characteristic with a saturation magnetization (Ms) of 0.146 x 10(-2) emu/cm3 and a coercive field of 60 Oe. And the cause of the magnetic properties has been discussed in detail.

  3. Broadband and omnidirectional light harvesting enhancement in photovoltaic devices with aperiodic TiO2 nanotube photonic crystal

    NASA Astrophysics Data System (ADS)

    Guo, Min; Su, Haijun; Zhang, Jun; Liu, Lin; Fu, Nianqing; Yong, Zehui; Huang, Haitao; Xie, Keyu

    2017-03-01

    Design of more effective broadband light-trapping elements to improve the light harvesting efficiency under both normal and tilted light for solar cells and other photonic devices is highly desirable. Herein we present a theoretical analysis on the optical properties of a novel TiO2 nanotube aperiodic photonic crystal (NT APC) following an aperiodic sequences and its photocurrent enhancement effect for dye-sensitized solar cells (DSSCs) under various incidence angles. It is found that, compared to regular PC, the designed TiO2 NT APC owns broader reflection region and a desired omnidirectional reflection (ODR) bandgaps, leading to considerable and stable photocurrent enhancement under both normal and oblique light. The effects of the structural parameters of the TiO2 NT APC, including the average lattice constant and the common sequence difference, on the optical properties, ODR bandgaps and absorption magnification of the integrated DSSCs are investigated in detail. Moreover, the angular dependence of photocurrent enhancement and angular compensation effect of such TiO2 NT APCs are also provided to offer a guidance on the optimum structural parameters design under different engineering application conditions.

  4. Cumulative effect of Fe2O3 on TiO2 nanotubes via atomic layer deposition with enhanced lithium ion storage performance

    NASA Astrophysics Data System (ADS)

    Lv, Xiaoxin; Deng, Jiujun; Sun, Xuhui

    2016-04-01

    Fe2O3 coated TiO2 nanotube (Fe2O3@TiO2 nanotube) composites anodes for lithium-ion batteries (LIBs) have been prepared by hydrothermal and atomic layer deposition (ALD) method. The composites anodes show a reversible capacity of 450 mAh g-1 after 150 cycles at the current density of 200 mA g-1, which is approximately two times of pure TiO2 nanotubes. Even at a high current density of 3200 mA g-1, the composite anodes still exhibit a good capacity of 198 mAh g-1, more than three times higher than that of pure TiO2 nanotubes. The good reversible capacity and rete capability of composite anodes indicate the cumulative effect of Fe2O3 on TiO2 nanotube by the integration of structural stability of TiO2 and high theoretical capacity of Fe2O3.

  5. [Research of the photoelectrocatalysis degradation of methylene blue of TiO2 nanotube array films annealed in oxygen atmospheres].

    PubMed

    Zhang, Xi; Liao, Lei; Ling, Yun-Han; Qin, Ai-Miao; Zhao, Cheng-Gen; Zhao, Fei-Chao

    2011-11-01

    Well-aligned and uniform titanium dioxide nanotube arrays were fabricated in situ on titanium substrate by electrochemical anodic oxidation. SEM images indicate that the TiO2 nanotubes are well organized into high-density uniform arrays,with diameter ranging in size from 70 to 100 nm. The XRD patterns show that the sample fabricated by anodic oxidation is amorphous without being annealed. As the 500 degrees C annealed sample crystallized in the anatase phase, which is in good photocatalytic activity. In quartz glass reactor, the photoelectrocatalytic degradation of MB in aqueous solutions as well as the effect factors and then to 0.1 mol/L NaCl as the electrolyte, under with in oxygen atmospheres annealed the applied bias is 0.5 V and has a pH = 3.25, light intensity is 1 000 microW/cm2 and the surface area of nano-tube array film conditions, will help to improve the TiO2 nanotubes array film photoelectrocatalysis degradation of MB degradation efficiency is 99.56%. The results of EIS analyses revealed that the surface reaction step was the only rate limiting step either for the photoelectrocatalytic process. The extra bias potential could decrease the values of the electron-transfer resistance and increase the separation efficiency of photogenerated electron-hole pairs.

  6. Effect of doping level of colored TiO2 nanotube arrays fabricated by electrochemical self-doping on electrochemical properties.

    PubMed

    Kim, Choonsoo; Kim, Seonghwan; Hong, Sung Pil; Lee, Jaehan; Yoon, Jeyong

    2016-06-07

    Recently, two types of TiO2 nanotube arrays (NTAs) (blue- and black-colored TiO2 NTAs), which are easily fabricated by electrochemical self-doping, have gained much attention due particularly to their enhanced capacitive and oxidant-generating properties. These enhanced electrochemical properties mean that they have potential as basic materials for energy and environmental applications, such as in supercapacitors and anodes for water treatment. However, the understanding of the effect of the doping level of these TiO2 NTAs on their electrochemical properties is limited because there is no direct comparison or relevant discussion of their respective electrochemical properties under the same conditions, despite the similar surface characteristics of the TiO2 NTAs obtained by comparable electrochemical doping. Therefore, the objective of this study was to investigate the effect of the doping level of blue and black TiO2 NTAs on their electrochemical properties, including the capacitive and oxidant-generating properties. Although no significant difference in their surface properties was found using SEM, XRD and XPS, the black TiO2 NTA revealed a slightly higher doping level than the blue TiO2 NTA, which is caused by the order of the electrochemical self-doping and annealing conditions. With the different doping levels of the two TiO2 NTAs, the black TiO2 NTA showed a higher areal capacitance, indicating good capacitive properties, and better service life in oxidant-generation than that of the blue TiO2 NTA. The blue TiO2 NTA exhibited a larger oxygen evolution overpotential and higher chlorine evolution efficiency than that of the black TiO2 NTA. We report that the new knowledge on blue and black TiO2 NTAs from this study can contribute to the further development of supercapacitors and oxidant-generating anodes for water treatment.

  7. Gas sensing properties and p-type response of ALD TiO2 coated carbon nanotubes.

    PubMed

    Marichy, Catherine; Donato, Nicola; Latino, Mariangela; Willinger, Marc Georg; Tessonnier, Jean-Philippe; Neri, Giovanni; Pinna, Nicola

    2015-01-16

    Amorphous titanium dioxide-coated carbon nanotubes (CNTs) were prepared by atomic layer deposition (ALD) and investigated as sensing layers for resistive NO2 and O2 gas sensors. By varying ALD process conditions and CNT structure, heterostructures with different metal oxide grain size, morphology and coating thickness were synthesized. Higher responses were observed with homogeneous and continuous 5.5 nm thick films onto CNTs at an operating temperature of 150 °C, while CNTs decorated with either discontinuous film or TiO2 nanoparticles showed a weak response close to the one of device made of bare CNTs. An unexpected p-type behavior in presence of the target gas was also noticed, independently of the metal oxide morphology and thickness. Based on previous works, hypotheses were made in order to explain the p-type behavior of TiO2/CNT sensors.

  8. Langmuir-Blodgett assembly of visible light responsive TiO2 nanotube arrays/graphene oxide heterostructure

    NASA Astrophysics Data System (ADS)

    Chen, Ying; Gao, Hongyan; Wei, Danming; Dong, Xinju; Cao, Yan

    2017-01-01

    The hybrid nanocomposites of titanium dioxide (TiO2) with graphene oxide (GO) have recently garnered much attention as electronic devices, energy conversion devices, photocatalysts and other applications. In this study, Langmuir-Blodgett (LB) assembly method was firstly reported to prepare a TiO2 nanotube arrays (TNA)-GO heterostructure. The as-prepared TNA-GO sample was characterized by X-ray diffraction, Raman spectra, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The promising characteristics of this TNA-GO material, the inexpensive, nontoxic and highly visible-light responsiveness, may raise the potential uses in many, various photocatalytic applications.

  9. Effect of TiCl4 Post-Treatment on the Embedded-Type TiO2 Nanotubes Dye-Sensitized Solar Cells.

    PubMed

    Kim, Kang-Pil; Kim, Jeong-Hwa; Hwang, Dae-Kue; Sung, Shi-Joon; Heo, Young-Woo

    2015-10-01

    We have studied the effect of TiCl4 post-treatment on the embedded-type TiO2 nanotubes (NT)-dye-sensitized solar cells (DSSCs). The TiO2 nanoparticles layer formed on TiO2 NTs surface by TiCl4 post-treatment showed different morphologies depending on TiCl4 treatment temperature. These different morphologies influenced the cell efficiency of TiO2 NT-DSSCs. The TiO2 NT treated with TiCl4 at 50 °C exhibited a rougher surface than that treated at 70 °C. The rough surface of the TiO2 NT improved the charge exchange between the dye and electrolyte. The TiO2 NT treated with TiCl4 at 50 °C showed better fill factor and cell efficiency than that treated at 70 °C. The TiCl4 post-treatment of TiO2 NT was effective at conditions of low temperature and long times. The TiO2 NT-DSSCs with TiCl4 post-treatment at 50 °C for 1.5 h showed an efficiency of 6.52%.

  10. Reliable metal deposition into TiO(2) nanotubes for leakage-free interdigitated electrode structures and use as a memristive electrode.

    PubMed

    Liu, Ning; Lee, Kiyoung; Schmuki, Patrik

    2013-11-18

    Nearly 100 % filling of TiO2 nanotubes with metals, including Ag, Cu, Au, and Pt, was achieved by defect-sealing treatment at the bottom of the nanotubes, followed by metal deposition using nuclei formation/coalescence. The resulting short-circuit-free interdigitated electrode configurations can, for example, be used to fabricate memristive electrodes.

  11. Hierarchical fabrication of heterojunctioned SrTiO3/TiO2 nanotubes on 3D microporous Ti substrate with enhanced photocatalytic activity and adhesive strength

    NASA Astrophysics Data System (ADS)

    Zhou, Jie; Yin, Lu; Zha, Kang; Li, Huirong; Liu, Zhiyuan; Wang, Jianxin; Duan, Ke; Feng, Bo

    2016-03-01

    Recently, construction of three-dimensional (3D) architecture and design of heterostructure have been proved to be two important approaches for improving photocatalytic (PC) properties of TiO2-based catalysts. In this work, a 3D microporous surface on Ti substrate (MPT) was prepared by simple acid etching. Then, heterojunctioned SrTiO3/TiO2 nanotubes with dominant {001} facets of anatase TiO2were successfully fabricated on MPT by combining anodization with hydrothermal treatment. The 3D microporous-patterned SrTiO3/TiO2 nanotubes heterojunction shows significantly enhanced photo-current density and ∼200% improved PC effect in degradation of Rhodamine B owing to its higher specific surface area, stronger light-harvesting ability and positive heterojunction effect in comparison with TiO2 nanotubes formed on flat Ti substrate. Moreover, the 3D microporous structure on Ti substrate improved the adhesive strength between the nanotubes layer and Ti substrate, which can be ascribed to the effective release of internal stress. Therefore, this present strategy is expected to expand the application of TiO2-based catalysts in many fields which require excellent PC properties and mechanical stability.

  12. Porous TiO2 Nanotubes with Spatially Separated Platinum and CoOx Cocatalysts Produced by Atomic Layer Deposition for Photocatalytic Hydrogen Production.

    PubMed

    Zhang, Jiankang; Yu, Zhuobin; Gao, Zhe; Ge, Huibin; Zhao, Shichao; Chen, Chaoqiu; Chen, Shuai; Tong, Xili; Wang, Meihua; Zheng, Zhanfeng; Qin, Yong

    2017-01-16

    Efficient separation of photogenerated electrons and holes, and associated surface reactions, is a crucial aspect of efficient semiconductor photocatalytic systems employed for photocatalytic hydrogen production. A new CoOx /TiO2 /Pt photocatalyst produced by template-assisted atomic layer deposition is reported for photocatalytic hydrogen production on Pt and CoOx dual cocatalysts. Pt nanoclusters acting as electron collectors and active sites for the reduction reaction are deposited on the inner surface of porous TiO2 nanotubes, while CoOx nanoclusters acting as hole collectors and active sites for oxidation reaction are deposited on the outer surface of porous TiO2 nanotubes. A CoOx /TiO2 /Pt photocatalyst, comprising ultra-low concentrations of noble Pt (0.046 wt %) and CoOx (0.019 wt %) deposited simultaneously with one atomic layer deposition cycle, achieves remarkably high photocatalytic efficiency (275.9 μmol h(-1) ), which is nearly five times as high as that of pristine TiO2 nanotubes (56.5 μmol h(-1) ). The highly dispersed Pt and CoOx nanoclusters, porous structure of TiO2 nanotubes with large specific surface area, and the synergetic effect of the spatially separated Pt and CoOx dual cocatalysts contribute to the excellent photocatalytic activity.

  13. Biomimetic Approach to Solar Cells Based on TiO2 Nanotubes

    DTIC Science & Technology

    2008-04-01

    reviewing instructions, searching existing data sources , gathering and maintaining the data needed, and completing and reviewing the collection information... terpineol as solvent and ethyl cellulose as binder. The aqueous system was optimized with a mass percent of 15.9%, 4.8%, and 79.3% of TiO2...hydroxyethylcellulose, and water, respectively. The terpineol - based system was optimized with a mass percent of 17.7%, 4.3%, and 79.4% of TiO2

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

    PubMed

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

    2014-04-01

    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 (TiO2) 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 TiO2 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.

  15. Dual effects and mechanism of TiO2 nanotube arrays in reducing bacterial colonization and enhancing C3H10T1/2 cell adhesion

    PubMed Central

    Peng, Zhaoxiang; Ni, Jiahua; Zheng, Kang; Shen, Yandong; Wang, Xiaoqing; He, Guo; Jin, Sungho; Tang, Tingting

    2013-01-01

    Competition occurs between the osteoblasts in regional microenvironments and pathogens introduced during surgery, on the surface of bone implants, such as joint prostheses. The aim of this study was to modulate bacterial and osteoblast adhesion on implant surfaces by using a nanotube array. Titanium oxide (TiO2) nanotube arrays, 30 nm or 80 nm in diameter, were prepared by a two-step anodization on titanium substrates. Mechanically polished and acid-etched titanium samples were also prepared to serve as control groups. The standard strains of Staphylococcus epidermidis (S. epidermidis, American Type Culture Collection [ATCC]35984) and mouse C3H10T1/2 cell lines with osteogenic potential were used to evaluate the different responses to the nanotube arrays, in bacteria and eukaryotic cells. We found that the initial adhesion and colonization of S. epidermidis on the surface of the TiO2 nanotube arrays were significantly reduced and that the adhesion of C3H10T1/2 cells on the surface of the TiO2 nanotube arrays was significantly enhanced when compared with the control samples. Based on a surface analysis of all four groups, we observed increased surface roughness, decreased water contact angles, and an enhanced concentration of oxygen and fluorine atoms on the TiO2 nanotube surface. We conclude that the TiO2 nanotube surface can reduce bacterial colonization and enhance C3H10T1/2 cell adhesion; multiple physical and chemical properties of the TiO2 nanotube surface may contribute to these dual effects. PMID:23983463

  16. Effects of the large distribution of CdS quantum dot sizes on the charge transfer interactions into TiO2 nanotubes for photocatalytic hydrogen generation.

    PubMed

    González-Moya, Johan R; Garcia-Basabe, Yunier; Rocco, Maria Luiza M; Pereira, Marcelo B; Princival, Jefferson L; Almeida, Luciano C; Araújo, Carlos M; David, Denis G F; da Silva, Antonio Ferreira; Machado, Giovanna

    2016-07-15

    Hydrogen fuels generated by water splitting using a photocatalyst and solar irradiation are currently gaining the strength to diversify the world energy matrix in a green way. CdS quantum dots have revealed a hydrogen generation improvement when added to TiO2 materials under visible-light irradiation. In the present paper, we investigated the performance of TiO2 nanotubes coupled with CdS quantum dots, by a molecular bifunctional linker, on photocatalytic hydrogen generation. TiO2 nanotubes were obtained by anodization of Ti foil, followed by annealing to crystallize the nanotubes into the anatase phase. Afterwards, the samples were sensitized with CdS quantum dots via an in situ hydrothermal route using 3-mercaptopropionic acid as the capping agent. This sensitization technique permits high loading and uniform distribution of CdS quantum dots onto TiO2 nanotubes. The XPS depth profile showed that CdS concentration remains almost unchanged (homogeneous), while the concentration relative to the sulfate anion decreases by more than 80% with respect to the initial value after ∼100 nm in depth. The presence of sulfate anions is due to the oxidation of sulfide and occurs in greater proportion in the material surface. This protection for air oxidation inside the nanotubular matrix seemingly protected the CdS for photocorrosion in sacrificial solution leading to good stability properties proved by long duration, stable photocurrent measurements. The effect of the size and the distribution of sizes of CdS quantum dots attached to TiO2 nanotubes on the photocatalytic hydrogen generation were investigated. The experimental results showed three different behaviors when the reaction time of CdS synthesis was increased in the sensitized samples, i.e. similar, deactivation and activation effects on the hydrogen production with regard to TiO2 nanotubes. The deactivation effect was related to two populations of sizes of CdS, where the population with a shorter band gap acts as a

  17. Effects of the large distribution of CdS quantum dot sizes on the charge transfer interactions into TiO2 nanotubes for photocatalytic hydrogen generation

    NASA Astrophysics Data System (ADS)

    González-Moya, Johan R.; Garcia-Basabe, Yunier; Rocco, Maria Luiza M.; Pereira, Marcelo B.; Princival, Jefferson L.; Almeida, Luciano C.; Araújo, Carlos M.; David, Denis G. F.; Ferreira da Silva, Antonio; Machado, Giovanna

    2016-07-01

    Hydrogen fuels generated by water splitting using a photocatalyst and solar irradiation are currently gaining the strength to diversify the world energy matrix in a green way. CdS quantum dots have revealed a hydrogen generation improvement when added to TiO2 materials under visible-light irradiation. In the present paper, we investigated the performance of TiO2 nanotubes coupled with CdS quantum dots, by a molecular bifunctional linker, on photocatalytic hydrogen generation. TiO2 nanotubes were obtained by anodization of Ti foil, followed by annealing to crystallize the nanotubes into the anatase phase. Afterwards, the samples were sensitized with CdS quantum dots via an in situ hydrothermal route using 3-mercaptopropionic acid as the capping agent. This sensitization technique permits high loading and uniform distribution of CdS quantum dots onto TiO2 nanotubes. The XPS depth profile showed that CdS concentration remains almost unchanged (homogeneous), while the concentration relative to the sulfate anion decreases by more than 80% with respect to the initial value after ˜100 nm in depth. The presence of sulfate anions is due to the oxidation of sulfide and occurs in greater proportion in the material surface. This protection for air oxidation inside the nanotubular matrix seemingly protected the CdS for photocorrosion in sacrificial solution leading to good stability properties proved by long duration, stable photocurrent measurements. The effect of the size and the distribution of sizes of CdS quantum dots attached to TiO2 nanotubes on the photocatalytic hydrogen generation were investigated. The experimental results showed three different behaviors when the reaction time of CdS synthesis was increased in the sensitized samples, i.e. similar, deactivation and activation effects on the hydrogen production with regard to TiO2 nanotubes. The deactivation effect was related to two populations of sizes of CdS, where the population with a shorter band gap acts as a

  18. Electrochemical Infilling of CuInSe2 within TiO2 Nanotube Layers and Subsequent Photoelectrochemical Studies

    PubMed Central

    Das, Sayantan; Sopha, Hanna; Krbal, Milos; Zazpe, Raul; Podzemna, Veronika; Prikryl, Jan

    2017-01-01

    Abstract Anodic self‐organized TiO2 nanotube layers (with different aspect ratios) were electrochemically infilled with CuInSe2 nanocrystals with the aim to prepare heterostructures with a photoelectrochemical response in the visible light. The resulting heterostructure assembly was confirmed by field‐emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and X‐ray diffraction (XRD). High incident photon‐to‐electron conversion efficiency values exceeding 55% were obtained in the visible‐light region. The resulting heterostructures show promise as a candidate for solid‐state solar cells. PMID:28392991

  19. Characterization of self-organized TiO2 nanotubes on Ti-4Zr-22Nb-2Sn alloys and the application in drug delivery system.

    PubMed

    Liang, Y Q; Cui, Z D; Zhu, S L; Yang, X J

    2011-03-01

    In this study, the self-organized TiO(2) nanotubes grown by anodization of Ti-4Zr-22Nb-2Sn at different potentials, concentration of NH(4)F and anodization time was investigated. The morphology of nanotubes was observed by FE-SEM. The drug-loaded nanotubes were also fabricated in aqueous media containing minocycline hydrochloride. They were characterized by SEM, XPS and FT-IR. The results showed that the drug of minocycline hydrochloride (MH) was loaded in the nanotubes. The release effects were studied in phosphate buffer solution (PBS). The release rate of MH from TiO(2) nanotubes with shorter tube length in PBS was lower than the one of MH from longer nanotubes. The sustaining release time could last at least 150 h. Hence, it is a promising method to eliminate the harmful reactions by carrying drug in the tubes when the titanium alloys were used as biomedical implants.

  20. Spectroscopic studies of porphyrin functionalized multiwalled carbon nanotubes and their interaction with TiO2 nanoparticles surface

    NASA Astrophysics Data System (ADS)

    Zannotti, Marco; Giovannetti, Rita; D'Amato, Chiara Anna; Rommozzi, Elena

    2016-01-01

    UV-vis and fluorescence investigations about the non-covalent interaction, in ethanolic solutions, of multi-wall carbon nanotube (MWCNT) with Coproporphyrin-I, and its Cu(II) and Zn(II) complexes (MCPIs) have been reported. Evidence of binding between MWCNTs and porphyrins was discovered from spectral adsorption decrease with respect to free porphyrins and by the exhibition of photoluminescence quenching with respect to free porphyrins demonstrating that MWCNT@MCPIs are potential donor-acceptor complexes. Equilibrium and kinetic aspects in the interactions with monolayer transparent TiO2 thin films with the obtained MWCNT@MCPIs are clarified showing their effective adsorption by porphyrin links on the TiO2 monolayer support, with respect to not only MWCNTs, according to the Langmuir model and with pseudo-first-order kinetics. Morphological description of the adsorption of MWCNT@MCPIs on TiO2 with scanning electron microscopy has been reported. The obtained experimental evidences describe therefore MWCNT@MCPIs as potential sensitizers in the DSSC (Dye-Sensitized Solar Cell) applications.

  1. Electrodeposition technique-dependent photoelectrochemical and photocatalytic properties of an In2S3/TiO2 nanotube array.

    PubMed

    Li, Yue; Luo, Shenglian; Wei, Zhendong; Meng, Deshui; Ding, Mingyue; Liu, Chengbin

    2014-03-07

    Electrodeposition is a very versatile tool to fabricate multicomponent TiO2 nanotube array (NTA) composites. However, the understanding of the correlation between the component structure and the fabrication technique has not been clearly investigated yet, though it has been observed that the performance of composites is bound up with the component structure. In this work, the photoelectrochemical properties of In2S3-TiO2 NTA composites prepared by CV electrodeposition, potentiostatic electrodeposition and pulse electrodeposition, respectively, were investigated. The results revealed that the as-prepared photoelectrodes exhibited electrodeposition technique-dependent properties, and the pulse prepared In2S3-TiO2 yielded the highest and stable photocurrent response, consequently exhibiting a superior photocatalytic activity in the degradation of p-nitrophenol (PNP). This may be attributed to the homogeneous, ultra-fine structure of In2S3 nanoparticles (NPs), which brings about a high charge separation efficiency. Furthermore, the trapping tests showed that both radicals and holes were the main active species in the photocatalytic degradation of PNP. This work not only provided a firm basis for maximizing photocatalytic activity via tuning fabrication techniques but also gave a deep insight into the photocatalytic mechanism.

  2. Carbon-Decorated TiO2 Nanotube Membranes: A Renewable Nanofilter for Charge-Selective Enrichment of Proteins.

    PubMed

    Xu, Jingwen; Yang, Lingling; Han, Yuyao; Wang, Yongmei; Zhou, Xuemei; Gao, Zhida; Song, Yan-Yan; Schmuki, Patrik

    2016-08-31

    In this work, we design a TiO2 nanomembrane (TiNM) that can be used as a nanofilter platform for selective enrichment of specific proteins. After a first use, the photocatalytic properties of TiO2 allow the decomposition of unwanted remnants on the substrate and thus make the platform reusable. To construct this platform, we fabricate a free-standing TiO2 nanotube array and remove the bottom oxide to form a both-end-open TiNM. By pyrolysis of the natural tube wall contamination, the walls become decorated with graphitic carbon patches (C/TiNM). Owing to the large surface area, the amphiphilic nature and the charge-adjustable character, this C/TiNM can be used to extract and enrich hydrophobic charged biomolecules. Using human serum albumin (HSA) as a model protein as well as protein mixtures, we show that the composite membrane exhibits a highly enhanced loading capacity and protein selectivity and is reusable after a short UV treatment.

  3. Electronic Structure of Semiconducting and Metallic Tubes in TiO2/Carbon Nanotube Heterojunctions: Density Functional Theory Calculations.

    PubMed

    Long, Run

    2013-04-18

    The electronic structure of the TiO2(110) surface interfaced with both a semiconducting and metallic carbon nanotube (CNT) was investigated by density functional theory. Our simulations rationalized visible light photocatalytic activity of CNT/TiO2 hybrid materials higher than that under ultraviolent irradiation and showed that the photoactivity of a semiconducting CNT decorating TiO2 is better than that of the metallic CNT/TiO2 system due to efficient charge separation across the interface. This suggests that semiconducting CNT/TiO2 could be a potential photovoltaic material. In contrast, strong interaction between a metallic CNT and TiO2 leads to large charge transfer. Such charge transfer reduces the built-in potential, in turn resulting in inefficient charge separation. Functionalizing the metallic CNT with a small platinum cluster can increase the built-in potential and drive charge separation. These observations indicate that the CNT/TiO2 interface can be a potential photovoltaic material by a metal cluster decorating a CNT despite a real tube being composed of the mixture of metallic and semiconducting CNTs.

  4. Narrowing of band gap and effective charge carrier separation in oxygen deficient TiO2 nanotubes with improved visible light photocatalytic activity.

    PubMed

    Choudhury, Biswajit; Bayan, Sayan; Choudhury, Amarjyoti; Chakraborty, Purushottam

    2016-03-01

    Oxygen vacancies are introduced into hydrothermally processed TiO2 nanotube by vacuum calcination. Formation of oxygen vacancies modifies the local coordination in TiO2 as evident from Raman spectroscopy and secondary ion mass spectrometry (SIMS) results. The surface area is increased from 172.5m(2)/g in pure to 405.1m(2)/g in defective TiO2 nanotube. The mid-band gap electronic states created by oxygen vacancies are mostly responsible for the effective narrowing of band gap. Charge carrier separation is sufficiently prolonged as the charged oxygen defect states inhibit facile carrier recombination. With high surface area, narrowed band gap and separated charge carriers defective TiO2 nanotube is a suitable candidate in the photodegradation of methylene blue (MB) and phenol under visible light illumination. Photosensitized electron transfer from MB to the conduction band of TiO2 and the photodegradation of MB is facilitated in presence of high density of oxygen vacancies. Unlike MB, phenol absorbs in the UV region and does not easily excited under visible light. Phenol shows activity under visible light by forming charge transfer complex with TiO2. Defect trapped carriers become available at the phenol-TiO2 interface and finally interact with phenol molecule and degrade it.

  5. TiO2 nanotube arrays modified with Cr-doped SrTiO3 nanocubes for highly efficient hydrogen evolution under visible light.

    PubMed

    Jiao, Zhengbo; Zhang, Yan; Chen, Tao; Dong, Qingsong; Lu, Gongxuan; Bi, Yingpu

    2014-02-24

    In recent decades, solar-driven hydrogen production over semiconductors has attracted tremendous interest owing to the global energy and environmental crisis. Among various semiconductor materials, TiO2 exhibits outstanding photocatalytic properties and has been extensively applied in diverse photocatalytic and photoelectric systems. However, two major drawbacks limit practical applications, namely, high charge-recombination rate and poor visible-light utilization. In this work, heterostructured TiO2 nanotube arrays grafted with Cr-doped SrTiO3 nanocubes were fabricated by simply controlling the kinetics of hydrothermal reactions. It was found that coupling TiO2 nanotube arrays with regular SrTiO3 nanocubes can significantly improve the charge separation. Meanwhile, doping Cr cations into SrTiO3 nanocubes proved to be an effective and feasible approach to enhance remarkably the visible-light response, which was also confirmed by theoretical calculations. As a result, the rate of photoelectrochemical hydrogen evolution of these novel heteronanostructures is an order of magnitude larger than those of TiO2 nanotube arrays and other previously reported SrTiO3 /TiO2 nanocomposites under visible-light irradiation. Furthermore, the as-prepared Cr-doped SrTiO3 /TiO2 heterostructures exhibit excellent durability and stability, which are favorable for practical hydrogen production and photoelectric nanodevices.

  6. Enhanced Self-Assembly of Crystalline, Large-Area, and Periodicity-Tunable TiO2 Nanotube Arrays on Various Substrates.

    PubMed

    Liang, Xiaoguang; Zhang, Heng; Li, Ho-Wa; Shu, Lei; Cheung, HoYuen; Li, Dapan; Yip, SenPo; Yang, Qing Dan; Wong, Chun-Yuen; Tsang, Sai-Wing; Ho, Johnny C

    2017-02-22

    Due to their superior physical properties, titanium dioxide (TiO2) nanotube arrays are one of the most investigated nanostructure systems in materials science until now. However, it is still a great challenge to achieve damage-free techniques to realize controllable, cost-effective, and high-performance TiO2 nanotube arrays on both rigid and flexible substrates for different technological applications. In this work, we demonstrate a unique strategy to achieve self-assemble crystalline, large-area, and regular TiO2 nanotube arrays on various substrates via hybrid combination of conventional semiconductor processes. Besides the usual applications of TiO2 as carrier transport layers in thin-film electronic devices, we demonstrate that the periodic TiO2 nanotube arrays can show the effect of optical grating with large-area uniformity. Specifically, the fabricated nanotube geometries, such as the tube height, pitch, diameter, and wall thickness, as well as the crystallinity can be reliably controlled by varying the processing conditions. More importantly, utilizing these nanotube arrays in perovskite solar cells can further enhance the optical absorption, leading to improved power conversion efficiency. In contrast to other typical template-assisted fabrication approaches, we employ a soft template here, which would enable the construction of nanotube arrays without any significant damage associated with template removal. Furthermore, without the thermal restriction of underlying substrates, these crystalline nanotube arrays can be transferred to mechanically flexible substrates by a simple one-step method, which can expedite these nanotubes for potential utilization in other application domains.

  7. Fabrication of In2S3 nanoparticle decorated TiO2 nanotube arrays by successive ionic layer adsorption and reaction technique and their photocatalytic application.

    PubMed

    Zhang, Zhenrong; Tang, Yanhong; Liu, Chengbin; Wan, Long

    2014-06-01

    In2S3 nanoparticle (NP) decorated self-organized TiO2 nanotube array (In2S3/TiO2 NT) hybrids were fabricated via simple successive ionic layer adsorption and reaction (SILAR) technique. The In2S3 NPs in a size of about 15 nm were found to deposit on the top surface of the highly oriented TiO2 NT while without clogging the tube entrances. The loading amount of In2S3 NPs on the TiO2 NT was controlled by the cycle number of SILAR deposition. Compared with the bare TiO2 NT, the In2S3/TiO2 NT hybrids showed stronger absorption in the visible light region and significantly enhanced photocurrent density. The photocatalytic activity of the In2S3/TiO2 NT photocatalyst far exceeds that of bare TiO2 NT in the degradation of typical herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) under simulated solar light. After 160-min irradiation, almost 100% 2,4-D removal is obtained on the 7-In2S3/TiO2 NT prepared through seven SILAR deposition cycles, much higher than 26% on the bare TiO2 NT. After 10 successive cycles of photocatalytic process with total 1,600 min of irradiation, In2S3/TiO2 NT maintained as high 2,4-D removal efficiency as 95.1% with good stability and easy recovery, which justifies the potential of the photocatalytic system in application for the photocatalytic removal of organic pollutants such as herbicides or pesticides from water.

  8. An integrated power pack of dye-sensitized solar cell and Li battery based on double-sided TiO2 nanotube arrays.

    PubMed

    Guo, Wenxi; Xue, Xinyu; Wang, Sihong; Lin, Changjian; Wang, Zhong Lin

    2012-05-09

    We present a new approach to fabricate an integrated power pack by hybridizing energy harvest and storage processes. This power pack incorporates a series-wound dye-sensitized solar cell (DSSC) and a lithium ion battery (LIB) on the same Ti foil that has double-sided TiO(2) nanotube (NTs) arrays. The solar cell part is made of two different cosensitized tandem solar cells based on TiO(2) nanorod arrays (NRs) and NTs, respectively, which provide an open-circuit voltage of 3.39 V and a short-circuit current density of 1.01 mA/cm(2). The power pack can be charged to about 3 V in about 8 min, and the discharge capacity is about 38.89 μAh under the discharge density of 100 μA. The total energy conversion and storage efficiency for this system is 0.82%. Such an integrated power pack could serve as a power source for mobile electronics.

  9. Photovoltaic properties of dye sensitised solar cells using TiO2 nanotube arrays for photoanodes: Role of hydrochloric acid treatment

    NASA Astrophysics Data System (ADS)

    Liu, Tian; Wang, Baoyuan; Xie, Jian; Li, Quantong; Zhang, Jun; Asghar, Muhammad Imran; Lund, Peter D.; Wang, Hao

    2015-11-01

    A hydrochloric acid treatment was performed to modify the surface of TiO2 nanotube arrays for improving the photovoltaic performance of dye-sensitized solar cells. The microstructural, optical and photovoltaic properties of TiO2 nanotube arrays and the assembled cells were investigated in detail. It was found that HCl treatment does not change the morphology and crystallographic structure of the nanotube arrays, but it results in more hydroxyl groups on the TiO2 surface for dye adsorption and a surface protonation for both an improved dye adsorption and a higher quantum yield of electron injection. A major performance enhancement was found which originated from the remarkable increase in the dye adsorption. A power conversion efficiency of 8.4%, JSC of ∼16.8 mA cm-2 and VOC of 0.7 V was observed when the photoanode was treated with a 0.1 M HCl solution.

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

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

    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 (TiO2) 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, TiO2 nanotubes were synthetized and doped with Ca and P by means of a novel methodology which relied, firstly, on the synthesis of TiO2 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 TiO2 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 CaCO3, Ca3(PO4)2, CaHPO4 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.

  11. Carbon-Pt nanoparticles modified TiO2 nanotubes for simultaneous detection of dopamine and uric acid.

    PubMed

    Mahshid, Sara; Luo, Shenglian; Yang, Lixia; Mahshid, Sahar Sadat; Askari, Masoud; Dolati, Abolghasem; Cai, Qingyun

    2011-08-01

    The present work describes sensing application of modified TiO2 nanotubes having carbon-Pt nanoparticles for simultaneous detection of dopamine and uric acid. The TiO2 nanotubes electrode was prepared using anodizing method, followed by electrodeposition of Pt nanoparticles onto the tubes. Carbon was deposited by decomposition of polyethylene glycol in a tube furnace to improve the conductivity. The C-Pt-TiO2 nanotubes modified electrode was characterized by cyclic voltammetry and differential pulse voltammetry methods. The modified electrode displayed high sensitivity towards the oxidation of dopamine and uric acid in a phosphate buffer solution (pH 7.00). The electro-oxidation currents of dopamine and uric acid were linearly related to the concentration over a wide range of 3.5 x 10(-8) M to 1 x 10(-5) M and 1 x 10(-7) M to 3 x 10(-5) M respectively. The limit of detection was determined as 2 x 10(-10) M for dopamine at signal-to-noise ratio of 3. The interference of uric acid was also investigated. Electro-oxidation currents of dopamine in the presence of fix amount of uric acid represented a linear behaviour towards successive addition of dopamine in range of 1 x 10(-7) M to 1 x 10(-5) M. Furthermore, in a solution containing dopamine, uric acid and ascorbic acid the overlapped oxidation peaks of dopamine and ascorbic acid could be easily separated by using C-Pt-TiO2 nanotubes modified electrode.

  12. Three-dimensional SnO2@TiO2 double-shell nanotubes on carbon cloth as a flexible anode for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Haifeng; Ren, Weina; Cheng, Chuanwei

    2015-07-01

    In this study, three-dimensional SnO2@TiO2 double-shell nanotubes on carbon cloth are synthesized by a combination of the hydrothermal method for ZnO nanorods and a subsequent SnO2 and TiO2 thin film coating with atomic layer deposition (ALD). The as-prepared SnO2@TiO2 double-shell nanotubes are further tested as a flexible anode for Li ion batteries. The SnO2@TiO2 double-shell nanotubes/carbon cloth electrode exhibited a high initial discharge capacity (e.g. 778.8 mA h g-1 at a high current density of 780 mA g-1) and good cycling performance, which could be attributed to the 3D double-layer nanotube structure. The interior space of the stable TiO2 hollow tube can accommodate the large internal stress caused by volume expansion of SnO2 and protect SnO2 from pulverization and exfoliation.

  13. Synthesis and Photocatalytic Properties of Ce-Doped TiO2 Nanotube Arrays via Anodic Oxidation

    NASA Astrophysics Data System (ADS)

    Kong, Junhan; Wang, Yongqian; Sun, Qimeng; Meng, Dawei

    2017-03-01

    Ce-doped TiO2 nanotube arrays (TNAs) were prepared successfully through one-step anodic oxidation methods. The structural and morphological features of the TNAs were monitored by x-ray diffraction and field emission scanning electron microscopy with energy dispersive spectroscopy. Ultraviolet-visible light absorption spectra showed the light absorption performances of TiO2 nanotubes in both ultraviolet (UV) and visible light regions. Also, the photocatalytic activities of these samples were measured by the photodegradation rate of methylene blue (MB). The result indicated that doping a moderate amount of cerium ions into TNAs increased the absorption of both ultraviolet light and visible light obviously. However, the excess amount of doping ions would destroy the tubular structure severely and decrease the specific surface area of TNAs sharply. It could directly lead to the decreasing of photocatalytic activitity of TNAs. Furthermore, the best photodegradation rate of the Ce-doped TNAs on MB reached to 95.6%, which had a huge improvement comparing with pure TNAs.

  14. Ag Nanoparticle–Functionalized Open-Ended Freestanding TiO2 Nanotube Arrays with a Scattering Layer for Improved Energy Conversion Efficiency in Dye-Sensitized Solar Cells

    PubMed Central

    Rho, Won-Yeop; Chun, Myeung-Hwan; Kim, Ho-Sub; Kim, Hyung-Mo; Suh, Jung Sang; Jun, Bong-Hyun

    2016-01-01

    Dye-sensitized solar cells (DSSCs) were fabricated using open-ended freestanding TiO2 nanotube arrays functionalized with Ag nanoparticles (NPs) in the channel to create a plasmonic effect, and then coated with large TiO2 NPs to create a scattering effect in order to improve energy conversion efficiency. Compared to closed-ended freestanding TiO2 nanotube array–based DSSCs without Ag or large TiO2 NPs, the energy conversion efficiency of closed-ended DSSCs improved by 9.21% (actual efficiency, from 5.86% to 6.40%) with Ag NPs, 6.48% (actual efficiency, from 5.86% to 6.24%) with TiO2 NPs, and 14.50% (actual efficiency, from 5.86% to 6.71%) with both Ag NPs and TiO2 NPs. By introducing Ag NPs and/or large TiO2 NPs to open-ended freestanding TiO2 nanotube array–based DSSCs, the energy conversion efficiency was improved by 9.15% (actual efficiency, from 6.12% to 6.68%) with Ag NPs and 8.17% (actual efficiency, from 6.12% to 6.62%) with TiO2 NPs, and by 15.20% (actual efficiency, from 6.12% to 7.05%) with both Ag NPs and TiO2 NPs. Moreover, compared to closed-ended freestanding TiO2 nanotube arrays, the energy conversion efficiency of open-ended freestanding TiO2 nanotube arrays increased from 6.71% to 7.05%. We demonstrate that each component—Ag NPs, TiO2 NPs, and open-ended freestanding TiO2 nanotube arrays—enhanced the energy conversion efficiency, and the use of a combination of all components in DSSCs resulted in the highest energy conversion efficiency. PMID:28335245

  15. Enhanced performance of dye-sensitized solar cells based on TiO2 nanotube membranes using an optimized annealing profile.

    PubMed

    Mohammadpour, F; Moradi, M; Lee, K; Cha, G; So, S; Kahnt, A; Guldi, D M; Altomare, M; Schmuki, P

    2015-01-31

    We use free-standing TiO2 nanotube membranes that are transferred onto FTO slides in front-side illuminated dye-sensitized solar cells (DSSCs). We investigate the key parameters for solar cell arrangement of self-ordered anodic TiO2 nanotube layers on the FTO substrate, namely the influence of the annealing procedure on the DSSC light conversion efficiency. The results show that using an optimal temperature annealing profile can significantly enhance the DSSC efficiency (in our case η = 9.8%), as it leads to a markedly lower density of trapping states in the tube oxide, and thus to strongly improved electron transport properties.

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

    PubMed

    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.

  17. Graphitic C3 N4 -Sensitized TiO2 Nanotube Layers: A Visible-Light Activated Efficient Metal-Free Antimicrobial Platform.

    PubMed

    Xu, Jingwen; Li, Yan; Zhou, Xuemei; Li, Yuzhen; Gao, Zhi-Da; Song, Yan-Yan; Schmuki, Patrik

    2016-03-14

    Herein, we use a facile procedure to graft a thin graphitic C3N4 (g-C3N4) layer on aligned TiO2 nanotube arrays (TiNT) by a one-step chemical vapor deposition (CVD) approach. This provides a platform to enhance the visible-light response of TiO2 nanotubes for antimicrobial applications. The formed g-C3N4/TiNT binary nanocomposite exhibits excellent bactericidal efficiency against Escherichia coli (E. coli) as a visible-light activated antibacterial coating, without the use of additional bactericides.

  18. Heterostructured ZnFe2O4/TiO2 nanotube arrays with remarkable visible-light photoelectrocatalytic performance and stability.

    PubMed

    Xie, Shan; Ouyang, Ke; Lao, Yueming; He, Peihao; Wang, Qun

    2017-05-01

    A series of heterostructured ZnFe2O4/TiO2-nanotube arrays (NTAs) with remarkable visible-light photoelectrocatalytic (PEC) activity were successfully prepared via a two-step process of anodization and impregnation, followed by annealing. The structure and morphology of the as-prepared ZnFe2O4/TiO2-NTAs samples, PEC degradation abilities and photoelectrochemical performances, as well as long-term stabilities toward degradation of methyl orange (MO) solution under visible-light irradiation were deeply investigated. Results showed that forming a heterojunction by combination of TiO2-NTAs with ZnFe2O4 successfully extended the absorption edge of TiO2-NTAs to visible-light region. Among all the ZnFe2O4/TiO2-NTAs samples, the 2-ZnFe2O4/TiO2-NTAs sample, named ZT(2), obtained the best PEC activity and the highest photocurrent density under visible-light irradiation. Moreover, the ZT(2) sample retained a good reproducibility and high stability after 20days of PEC degradation. The outstanding visible-light PEC activity and photocurrent response of the ZT(2) sample were attributed to the proper amount of ZnFe2O4 nanoparticles loaded onto the TiO2-NTAs, which not only dramatically improved the visible-light absorption of TiO2-NTAs, but also assisted the separation of photo-induced electron-hole pairs and reduced their recombination by forming a ZnFe2O4/TiO2-NTAs heterojunction. The reaction mechanism responsible for the enhanced visible-light PEC performance of the ZnFe2O4/TiO2-NTAs heterostructure was also discussed.

  19. Photodegradation performance and mechanism of 4-nonylphenol by WO3/TiO2 and TiO2 nanotube array photoelectrodes.

    PubMed

    Xin, Yanjun; Wang, Gang; Zhu, Xiangwei; Gao, Mengchun; Liu, Yongping; Chen, Qinghua

    2017-02-20

    TiO2 Nanotube arrays (TNA) and WO3-coated TNA photoelectrodes were fabricated using an in situ anodization and pulse electrochemical deposition technology. The performance of the TNA photoelectrodes in the photocatalytic (PC) and photoelectrocatalytic (PEC) degradation of 4-nonylphenol (4-NP) was investigated. The effects of the initial pH and the anions on the degradation rates and reaction mechanism of 4-NP were studied by the photoluminescence (PL) spectra and electrochemical impedance spectra (EIS). The degradation of 4-NP was fitted to a first-order reaction, and the apparent kinetic constants were 1.9 × 10(-2) min(-1) for TNA photoelectrodes and 2.4 × 10(-2) min(-1) for WO3/TNA photoelectrodes. When a bias potential of 1.0 V was applied, the values for TNA and WO3/TNA photoelectrodes increased to 2.5 × 10(-2) and 3.0 × 10(-2) min(-1), respectively. The degradation of 4-NP was controlled by a charge-transfer process one. WO3-decorated TNA photoelectrodes could increase the adsorption of 4-NP and promote its degradation. For the TNA and WO3/TNAs photoelectrodes, acid and alkaline solutions could facilitate the formation of hydroxyl radicals, whereas the removal of 4-NP was inhibited. The presence of [Formula: see text] , Cl(-), [Formula: see text] and [Formula: see text] has a negative effect on the formation of •OH, so did the removal of 4-NP. For the TNA photoelectrodes, the inhibition effect of [Formula: see text] on the formation of hydroxyl radicals and the removal of 4-NP was the most serious compared with that of [Formula: see text], Cl(-) and [Formula: see text] , while for the WO3/TNA photoelectrodes the inhibition effect of [Formula: see text] on the removal of 4-NP was maximum.

  20. Electrospinning directly synthesized metal nanoparticles decorated on both sidewalls of TiO2 nanotubes and their applications.

    PubMed

    Zhang, Guanhua; Duan, Huigao; Lu, Bingan; Xu, Zhi

    2013-07-07

    The hybrid structure of nanoparticle-decorated nanotubes has the advantage of both large specific surface areas of nanoparticles and anisotropic properties of nanotubes, which is desirable for many applications. In this study, Ag nanoparticles on highly porous TiO2 nanotubes (NTs) on both internal and external sidewalls (Ag@TiO2@Ag NTs) are directly synthesized by emulsion electrospinning and thermal evaporation for the first time. The Ag@TiO2@Ag NT heterostructures, which have large surface-to-volume ratios, improved electrical conductivity, and an excellent material synergetic effect, demonstrate excellent electrochemical properties and superior photocatalytic performance. The new method for the synthesis of Ag@TiO2@Ag NT heterostructures can be applied to fabricate various types of other novel metal nanoparticles (for example Au and Pt) on highly porous nanotubes on both internal and external sidewalls. The possible growth mechanism and reasons for excellent electrochemical properties and superior photocatalytic performance were discussed in detail.

  1. Stoichiometry, Length, and Wall Thickness Optimization of TiO2 Nanotube Array for Efficient Alcohol Sensing.

    PubMed

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

    2015-05-13

    The present study concerns development of an efficient alcohol sensor by controlling the stoichiometry, length, and wall thickness of electrochemically grown TiO2 nanotube array for its use as the sensing layer. Judicious variation of H2O content (0, 2, 10 and 100% by volume) in the mixed electrolyte comprising ethylene glycol and NH4F resulted into the desired variation of stoichiometry. The sensor study was performed within the temperature range of 27 to 250 °C for detecting the alcohols in the concentration range of 10-1000 ppm. The nanotubes grown with the electrolyte containing 2 vol % H2O offered the maximum response magnitude. For this stoichiometry, variation of corresponding length (1.25-2.4 μm) and wall thickness (19.8-9 nm) of the nanotubes was achieved by varying the anodization time (4-16 h) and temperatures (42-87 °C), respectively. While the variation of length influenced the sensing parameters insignificantly, the best response magnitude was achieved for ∼13 nm wall thickness. The underlying sensing mechanism was correlated with the experimental findings on the basis of structural parameters of the nanotubes.

  2. Double-layer electrode based on TiO2 nanotubes arrays for enhancing photovoltaic properties in dye-sensitized solar cells.

    PubMed

    He, Zuoli; Que, Wenxiu; Sun, Peng; Ren, Jiangbo

    2013-12-26

    The present work reports a rapid and facile method to fabricate a novel double-layer TiO2 photoanode, which is based on highly ordered TiO2 nanotube arrays and monodispersive scattering microspheres. This double-layer TiO2 sphere/TNTA photoanode have got many unique structural and optical properties from TiO2 scattering microspheres, such as high specific surface area, multiple interparticle scattering, and efficient light-harvesting. Results indicate that this as-fabricated double-layer TiO2 sphere/TNTA front-illumination dye-sensitized solar cell, which is fabricated from the TiO2 nanotube arrays with a 17.4 μm length after TiCl4 treatment, exhibits a pronounced power conversion efficiency of 7.24% under an AM1.5 G irradiation, which can be attributed to the increased incident photon-to-current conversion and light-harvesting efficiency.

  3. Enhanced osteogenic activity and anti-inflammatory properties of Lenti-BMP-2-loaded TiO2 nanotube layers fabricated by lyophilization following trehalose addition

    PubMed Central

    Zhang, Xiaochen; Zhang, Zhiyuan; Shen, Gang; Zhao, Jun

    2016-01-01

    To enhance biocompatibility and osseointegration between titanium implants and surrounding bone tissue, numerous efforts have been made to modify the surface topography and composition of Ti implants. In this paper, Lenti-BMP-2-loaded TiO2 nanotube coatings were fabricated by lyophilization in the presence of trehalose to functionalize the surface. We characterized TiO2 nanotube layers in terms of the following: surface morphology; Lenti-BMP-2 and trehalose release; their ability to induce osteogenesis, proliferation, and anti-inflammation in vitro; and osseointegration in vivo. The anodized TiO2 nanotube surfaces exhibited an amorphous glassy matrix perpendicular to the Ti surface. Both Lenti-BMP-2 and trehalose showed sustained release over the course of 8 days. Results from real-time quantitative polymerase chain reaction studies demonstrated that lyophilized Lenti-BMP-2/TiO2 nanotubes constructed with trehalose (Lyo-Tre-Lenti-BMP-2) significantly promoted osteogenic differentiation of bone marrow stromal cells but not their proliferation. In addition, Lyo-Tre-Lenti-BMP-2 nanotubes effectively inhibited lipopolysaccharide-induced interleukin-1β and tumor necrosis factor-α production. In vivo, the formulation also promoted osseointegration. This study presents a promising new method for surface-modifying biomedical Ti-based implants to simultaneously enhance their osteogenic potential and anti-inflammatory properties, which can better satisfy clinical needs. PMID:26869786

  4. Selective microwave sensors exploiting the interaction of analytes with trap states in TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Zarifi, M. H.; Farsinezhad, S.; Abdolrazzaghi, M.; Daneshmand, M.; Shankar, K.

    2016-03-01

    Sensing of molecular analytes by probing the effects of their interaction with microwaves is emerging as a cheap, compact, label-free and highly sensitive detection and quantification technique. Microstrip ring-type resonators are particularly favored for this purpose due to their planar sensing geometry, electromagnetic field enhancements in the coupling gap and compatibility with established printed circuit board manufacturing. However, the lack of selectivity in what is essentially a permittivity-sensing method is an impediment to wider adoption and implementation of this sensing platform. By placing a polycrystalline anatase-phase TiO2 nanotube membrane in the coupling gap of a microwave resonator, we engineer selectivity for the detection and differentiation of methanol, ethanol and 2-propanol. The scavenging of reactive trapped holes by aliphatic alcohols adsorbed on TiO2 is responsible for the alcohol-specific detection while the different short chain alcohols are distinguished on the basis of differences in their microwave response. Electrodeless microwave sensors which allow spectral and time-dependent monitoring of the resonance frequency and quality factor provide a wealth of information in comparison with electrode-based resistive sensors for the detection of volatile organic compounds. A high dynamic range (400 ppm-10 000 ppm) is demonstrated for methanol detection.Sensing of molecular analytes by probing the effects of their interaction with microwaves is emerging as a cheap, compact, label-free and highly sensitive detection and quantification technique. Microstrip ring-type resonators are particularly favored for this purpose due to their planar sensing geometry, electromagnetic field enhancements in the coupling gap and compatibility with established printed circuit board manufacturing. However, the lack of selectivity in what is essentially a permittivity-sensing method is an impediment to wider adoption and implementation of this sensing platform

  5. Acid-assisted hydrothermal synthesis of nanocrystalline TiO2 from titanate nanotubes: influence of acids on the photodegradation of gaseous toluene.

    PubMed

    Chen, Kunyang; Zhu, Lizhong; Yang, Kun

    2015-01-01

    In order to efficiently remove volatile organic compounds (VOCs) from indoor air, one-dimensional titanate nanotubes (TiNTs) were hydrothermally treated to prepare TiO2 nanocrystals with different crystalline phases, shapes and sizes. The influences of various acids such as CH3COOH, HNO3, HCl, HF and H2SO4 used in the treatment were separately compared to optimize the performance of the TiO2 nanocrystals. Compared with the strong and corrosive inorganic acids, CH3COOH was not only safer and more environmentally friendly, but also more efficient in promoting the photocatalytic activity of the obtained TiO2. It was observed that the anatase TiO2 synthesized in 15 mol/L CH3COOH solution exhibited the highest photodegradation rate of gaseous toluene (94%), exceeding that of P25 (44%) by a factor of more than two. The improved photocatalytic activity was attributed to the small crystallite size and surface modification by CH3COOH. The influence of relative humidity (20%-80%) on the performance of TiO2 nanocrystals was also studied. The anatase TiO2 synthesized in 15 mol/L CH3COOH solution was more tolerant to moisture than the other TiO2 nanocrystals and P25.

  6. Preparation and photoelectrocatalytic activity of ZnO nanorods embedded in highly ordered TiO(2) nanotube arrays electrode for azo dye degradation.

    PubMed

    Zhang, Zhonghai; Yuan, Yuan; Liang, Linhong; Cheng, Yuxiao; Shi, Guoyue; Jin, Litong

    2008-10-30

    In this article, the ZnO nanorods embedded in highly ordered TiO(2) nanotube arrays (ZnO/TiO(2) NR/Ts) electrodes were fabricated through two steps: (1) electrosynthesis of TiO(2) nanotube arrays (TiO(2) NTs) in HF solution by anodization method; (2) followed by cathodic electrodeposition of ZnO embedded in the TiO(2) nanotube arrays. The morphological characteristics and structures of ZnO/TiO(2) NR/Ts electrodes were examined by field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD) analysis, and UV-vis spectra. The linear-sweep photovoltammetry response on the ZnO/TiO(2) NR/Ts electrode was presented and the photocurrent was dramatically enhanced on the ZnO/TiO(2) NR/Ts electrode, comparing with that on bare TiO(2) NTs electrode. The photocatalytic and photoelectrocatalytic activity of ZnO/TiO(2) NR/Ts electrode was evaluated in degradation of methyl orange (MO) in aqueous solution.

  7. Controllable Synthesis of TiO2@Fe2O3 Core-Shell Nanotube Arrays with Double-Wall Coating as Superb Lithium-Ion Battery Anodes

    PubMed Central

    Zhong, Yan; Ma, Yifan; Guo, Qiubo; Liu, Jiaqi; Wang, Yadong; Yang, Mei; Xia, Hui

    2017-01-01

    Highlighted by the safe operation and stable performances, titanium oxides (TiO2) are deemed as promising candidates for next generation lithium-ion batteries (LIBs). However, the pervasively low capacity is casting shadow on desirable electrochemical behaviors and obscuring their practical applications. In this work, we reported a unique template-assisted and two-step atomic layer deposition (ALD) method to achieve TiO2@Fe2O3 core-shell nanotube arrays with hollow interior and double-wall coating. The as-prepared architecture combines both merits of the high specific capacity of Fe2O3 and structural stability of TiO2 backbone. Owing to the nanotubular structural advantages integrating facile strain relaxation as well as rapid ion and electron transport, the TiO2@Fe2O3 nanotube arrays with a high mass loading of Fe2O3 attained desirable capacity of ~520 mA h g−1, exhibiting both good rate capability under uprated current density of 10 A g−1 and especially enhanced cycle stability (~450 mA h g−1 after 600 cycles), outclassing most reported TiO2@metal oxide composites. The results not only provide a new avenue for hybrid core-shell nanotube formation, but also offer an insight for rational design of advanced electrode materials for LIBs. PMID:28098237

  8. Controllable Synthesis of TiO2@Fe2O3 Core-Shell Nanotube Arrays with Double-Wall Coating as Superb Lithium-Ion Battery Anodes

    NASA Astrophysics Data System (ADS)

    Zhong, Yan; Ma, Yifan; Guo, Qiubo; Liu, Jiaqi; Wang, Yadong; Yang, Mei; Xia, Hui

    2017-01-01

    Highlighted by the safe operation and stable performances, titanium oxides (TiO2) are deemed as promising candidates for next generation lithium-ion batteries (LIBs). However, the pervasively low capacity is casting shadow on desirable electrochemical behaviors and obscuring their practical applications. In this work, we reported a unique template-assisted and two-step atomic layer deposition (ALD) method to achieve TiO2@Fe2O3 core-shell nanotube arrays with hollow interior and double-wall coating. The as-prepared architecture combines both merits of the high specific capacity of Fe2O3 and structural stability of TiO2 backbone. Owing to the nanotubular structural advantages integrating facile strain relaxation as well as rapid ion and electron transport, the TiO2@Fe2O3 nanotube arrays with a high mass loading of Fe2O3 attained desirable capacity of ~520 mA h g‑1, exhibiting both good rate capability under uprated current density of 10 A g‑1 and especially enhanced cycle stability (~450 mA h g‑1 after 600 cycles), outclassing most reported TiO2@metal oxide composites. The results not only provide a new avenue for hybrid core-shell nanotube formation, but also offer an insight for rational design of advanced electrode materials for LIBs.

  9. Controllable Synthesis of TiO2@Fe2O3 Core-Shell Nanotube Arrays with Double-Wall Coating as Superb Lithium-Ion Battery Anodes.

    PubMed

    Zhong, Yan; Ma, Yifan; Guo, Qiubo; Liu, Jiaqi; Wang, Yadong; Yang, Mei; Xia, Hui

    2017-01-18

    Highlighted by the safe operation and stable performances, titanium oxides (TiO2) are deemed as promising candidates for next generation lithium-ion batteries (LIBs). However, the pervasively low capacity is casting shadow on desirable electrochemical behaviors and obscuring their practical applications. In this work, we reported a unique template-assisted and two-step atomic layer deposition (ALD) method to achieve TiO2@Fe2O3 core-shell nanotube arrays with hollow interior and double-wall coating. The as-prepared architecture combines both merits of the high specific capacity of Fe2O3 and structural stability of TiO2 backbone. Owing to the nanotubular structural advantages integrating facile strain relaxation as well as rapid ion and electron transport, the TiO2@Fe2O3 nanotube arrays with a high mass loading of Fe2O3 attained desirable capacity of ~520 mA h g(-1), exhibiting both good rate capability under uprated current density of 10 A g(-1) and especially enhanced cycle stability (~450 mA h g(-1) after 600 cycles), outclassing most reported TiO2@metal oxide composites. The results not only provide a new avenue for hybrid core-shell nanotube formation, but also offer an insight for rational design of advanced electrode materials for LIBs.

  10. TiO2 quantum dots embedded in bamboo-like porous carbon nanotubes as ultra high power and long life anodes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Tang, Yakun; Liu, Lang; Wang, Xingchao; Jia, Dianzeng; Xia, Wei; Zhao, Zongbin; Qiu, Jieshan

    2016-07-01

    TiO2 quantum dots embedded in bamboo-like porous carbon nanotubes have been constructed through the pyrolysis of sulfonated polymer nanotubes and TiO2 hybrids. The TiO2 quantum dots are formed during the pyrolysis, due to the space confinement within the highly cross-linked copolymer networks. The sulfonation degree of the polymer nanotubes is a critical factor to ensure the formation of the unique interpenetrating structure. The nanocomposites exhibit high reversible capacity of 523 mAh g-1 at 100 mA g-1 after 200 cycles, excellent rate capability and superior long-term cycling stability at high current density, which could attain a high discharge capacity of 189 mAh g-1 at 2000 mA g-1 for up to 2000 cycles. The enhanced electrochemical performance of the nanocomposites benefit from the uniform distribution of TiO2 quantum dots, high electronic conductivity of porous carbons and unique interpenetrating structure, which simultaneously solved the major problems of TiO2 anode facing the pulverization, loss of electrical contact and particle aggregation.

  11. Tailoring resistive switching properties of TiO2 with controlled incorporation of oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Cristians Rios, Alejandro; Aarão-Rodrigues, Lorena; Ronieri Cadore, Alisson; de Andrade, Rodrigo R.; Montoro, Luciano A.; Malachias, Angelo

    2016-08-01

    Reversible resistance states were extensively observed in thin film systems, and their physical properties were in most cases determined by the electric behavior of the dielectric layer placed between contacts. Here we include SnO2 nanoparticles on TiO2 dielectric films, inducing modifications of the resistive switching behavior. We show that the choice of oxide nanoparticles with dielectric constant smaller than the dielectric constant of the main oxide film guides conductive channels, increasing the extension of the Fowler-Nordheim (tunneling) conduction regime during their electroforming as the density of nanoparticles rises. It is found that the SnO2 nanoparticles show reduced impact on the resistive switching response of devices produced following this methodology. The formation of Ti4O7 conductive channels is discussed based on electric measurements as well as on scanning probe and electron microscopy techniques.

  12. Effect of irradiation on deposition of CdS in fabricating co-axial heterostructure of TiO2 nanotube arrays via chemical deposition

    NASA Astrophysics Data System (ADS)

    Pan, Rongjun; Wu, Yucheng; Li, Zhenglin; Fang, Zhijie

    2014-02-01

    Highly-ordered TiO2 nanotube arrays were synthesized electrochemically. Effect of irradiation on deposition of CdS in fabricating co-axial heterogeneous structure via chemical deposition was investigated. The field emission measurements revealed that irradiation with higher energy will help to achieve not only more CdS, but also neater and more intimate heterostructure through exerting influences on ion migration into the tubes and attachment of ions onto the tube walls. The XRD measurements revealed that the deposited nanotubes are composed of anatase TiO2, metallic Ti, and CdS. The optical characterization revealed that the photoabsorption and absorption activity are correlated with the energy of irradiation. The photoelectrochemical measurements revealed that the photocurrent density are also correlated with the energy of the irradiation. The stability of the obtained structures was governed by the contact between CdS and TiO2 as well as the amount of CdS.

  13. Morphology and crystallinity control of ultrathin TiO2 layers deposited on carbon nanotubes by temperature-step atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Guerra-Nuñez, Carlos; Zhang, Yucheng; Li, Meng; Chawla, Vipin; Erni, Rolf; Michler, Johann; Park, Hyung Gyu; Utke, Ivo

    2015-06-01

    Carbon nanotubes (CNTs) coated with titanium oxide (TiO2) have generated considerable interest over the last decade and become a promising nanomaterial for a wide range of energy applications. The efficient use of the outstanding electrical properties of this nanostructure relies heavily on the quality of the interface and the thickness and morphology of the TiO2 layer. However, complete surface coverage of the chemically inert CNTs and appropriate control of the morphology of the TiO2 layer have not been achieved so far. Here, we report a new strategy to obtain ultrathin TiO2 coatings deposited by ``Temperature-step'' Atomic Layer Deposition (TS-ALD) with complete surface coverage of non-functionalized multiwall carbon nanotubes (MWCNTs) and controlled morphology and crystallinity of the TiO2 film. This strategy consists of adjusting the temperature during the ALD deposition to obtain the desired morphology. Complete coverage of long non-functionalized MWCNTs with conformal anatase layers was obtained by using a low temperature of 60 °C during the nucleation stage followed by an increase to 220 °C during the growth stage. This resulted in a continuous and amorphous TiO2 layer, covered with a conformal anatase coating. Starting with the deposition at 220 °C and reducing to 60 °C resulted in sporadic crystal grains at the CNT/TiO2 interface covered with an amorphous TiO2 layer. The results were accomplished through an extensive study of nucleation and growth of titanium oxide films on MWCNTs, of which a detailed characterization is presented in this work.Carbon nanotubes (CNTs) coated with titanium oxide (TiO2) have generated considerable interest over the last decade and become a promising nanomaterial for a wide range of energy applications. The efficient use of the outstanding electrical properties of this nanostructure relies heavily on the quality of the interface and the thickness and morphology of the TiO2 layer. However, complete surface coverage of the

  14. The anodization voltage influence on the properties of TiO2 nanotubes grown by electrochemical oxidation.

    PubMed

    Alivov, Yahya; Pandikunta, Mahesh; Nikishin, Sergey; Fan, Z Y

    2009-06-03

    A systematic study of titanium dioxide (TiO2) nanotubes (NTs) grown by electrochemical anodization in NH4F + glycerol electrolyte has been carried out in a broad range of anodization voltage of 5-350 V and acid concentration of 0.1-0.7 wt%. It is found that NTs can be grown in the voltage range from 10 to 240 V. The maximum NH4F acid concentration at which NTs can be formed decreases with the anodization voltage (V(a)). The maximum NH4F acid concentration is 0.7% for V(a)<60 V, and it decreases to 0.1% at V(a) = 240 V. Glancing angle x-ray diffractometer (GAXRD) measurements show that as-grown amorphous TiO2 transforms to the anatase phase when annealed at 400 degrees C, and further transforms to the rutile phase at annealing temperatures higher than 500 degrees C. The transition temperature from anatase to rutile phase depends on the anodization conditions. The electrical resistivity of the NT increases by eight orders of magnitude when V(a) increases from 10 to 240 V.

  15. Role of interfacial strain in fiber-shaped solar cell based on TiO2 nanotube arrays.

    PubMed

    Fan, Xing; Huang, Lu; Liu, Zuohua; Tao, Changyuan

    2014-09-01

    This study reports the first equivalent circuit model for all-solid, fiber-shaped, dye-sensitized solar cell (DSSC), in order to reveal the internal catalytic reaction mechanism in this new type of solar cells. The counter electrode of the winding structure leads to negative impedance under high frequency, which is consistent with the model. The study further investigates the strain of the TiO2 nanotube (TNT) arrays and its influence on interfacial mechanism. As a unique characteristic of fiber-shaped DSSC, the strain of the TNT arrays strengthens the permeation of the electrolyte. The permeation not only improves the efficiency of interfacial photochemical reactions, but also magnifies the probability of the side reactions on the electrolyte/Ti interfaces. Therefore, both the variation of impedance and overall conversion efficiency exhibit similar inflection points. Different from that of traditional plate-type device, the interfacial impedance in the equivalent circuit of fiber-shaped devices should be treated as a variable for changes in TiO2 and CuI layers.

  16. Self-assembly of palladium nanoparticles on functional TiO2 nanotubes for a nonenzymatic glucose sensor.

    PubMed

    Chen, Xianlan; Li, Gang; Zhang, Guowei; Hou, Keyu; Pan, Haibo; Du, Min

    2016-05-01

    Polydiallyldimethylammonium chloride, PDDA, was used as a stabilizer and linker for functionalized TiO2 nanotubes (TiO2 NTs). Self-assembled process with palladium nanoparticles (NPs) was successfully synthesized and used for the oxidation of glucose on glassy carbon electrodes. Based on the voltammetric and amperometric results, Pd NPs efficiently catalyzed the oxidation of glucose at -0.05 V in the presence of 0.1 M NaCl and showed excellent resistance toward interference poisoning from such interfering species as ascorbic acid, uric acid and urea. To further increase sensitivity, the Pd NPs-PDDA-TiO2 NTs/GCE was electrochemically treated with H2SO4 and NaOH, the glucose oxidation current was magnified 2.5 times than that before pretreatments due to greatly enhancing the electron transport property of the sensor based on the increased defect sites and surface oxide species. In view of the physiological level of glucose, the wide linear concentration range of glucose (4×10(-7)-8×10(-4)M) with a detection limit of 8×10(-8)M (S/N=3) was obviously good enough for clinical application.

  17. Removal of toluene from water by photocatalytic oxidation with activated carbon supported Fe(3+)-doped TiO2 nanotubes.

    PubMed

    Yuan, Rongfang; Zhou, Beihai; Ma, Li

    2014-01-01

    In this work, activated carbon (AC)-supported TiO2 containing 1.0% (mass percent) of 1.0 at.% (atomic percent) Fe(3+)-doped TiO2 nanotubes (Fe-TNTs) were successfully synthesized. The catalyst was used to effectively decompose toluene in water under O3/UV conditions, and some properties including the morphology, X-ray photoelectron spectroscopy, X-ray diffraction patterns, specific surface area and UV-visible diffuse reflectance spectroscopy were analyzed. A removal efficiency of 90.7% was achieved in the presence of fresh AC-supported Fe-TNTs calcined at 550 °C, with a pseudo-first-order rate constant of 0.038/min. The removal efficiency of toluene was reduced when the catalysts were repeatedly used, since the amount of adsorption sites of the supporting substrates decreased. However, even after AC-supported catalyst was used four times, the removal efficiency of toluene was still sufficient in water treatment. The enhanced photocatalytic activity of AC-supported Fe-TNTs was related to the synergistic effect of AC adsorption and Fe-TNTs photocatalytic ozonation. The water from a petrochemical company in China was used to obtain the removal efficiency of the pollutants, and the toluene and total organic carbon removal efficiencies were 69.9% and 58.3%, respectively.

  18. Photocatalytic oxidation of methyl orange in water phase by immobilized TiO2-carbon nanotube nanocomposite photocatalyst

    NASA Astrophysics Data System (ADS)

    Dong, Yinmao; Tang, Dongyan; Li, Chensha

    2014-03-01

    We developed an immobilized carbon nanotube (CNT)-titanium dioxide (TiO2) heterostructure material for the photocatalytic oxidation of methyl orange in aqueous phase. The catalyst material was prepared via sol-gel method using multi-walled CNTs grown on graphite substrate as carriers. The multi-walled CNTs were synthesized from thermal decomposing of hydrocarbon gas directly on thin graphite plate, forming immobilized 3-dimensional network of CNTs. The nanophase TiO2 was synthesized coating on CNTs to form "coral"-shaped nanocomposite 3-dimensional network on graphite substrate, thus bringing effective porous structure and high specific surface area, and possessing the merit of dispersive powder photocatalysts, which is the fully available surface area, while adapting the requirement for clean and convenient manipulation as an immobilized photocatalyst. Moreover, the CNT-TiO2 heterostructure reduced the electron-hole pair recombination rate and enhanced the photoabsorption and the adsorption ability, resulting in elevating the photocatalysis efficiency. These synergistic effects due to the hybrid nature of the materials and interphase interaction greatly improved the catalytic activity, and demonstrated superior photocatalytic performances. Our work can be a significant inspiration for developing hybrid nano-phase materials to realize sophisticated functions, and bear tremendous significance for the development and applications of semiconductor nano-materials.

  19. Effect of annealing environments on self-organized TiO2 nanotubes for efficient photocatalytic applications.

    PubMed

    Hyam, Rajeshkumar Shankar; Lee, Jongseok; Cho, Eunju; Khim, Jeehyeong; Lee, Haigun

    2012-12-01

    In the present study, amorphous titanium dioxide (TiO2) nanotubes were synthesized by one-step anodization technique and subsequently annealed in different environments to investigate the effect of annealing atmospheres on the formation of different crystalline phases. X-ray Diffraction (XRD) patterns clearly showed the presence of anatase TiO2 phase with various crystallite sizes. The samples annealed in oxygen and air atmospheres at 500 degrees C showed a dominant anatase phase and a small amount of rutile phase, on the other hand, the samples annealed in nitrogen and argon atmospheres and in a vacuum at 500 degrees C contained the anatase phase only. XPS analysis of the samples showed a broadening in the binding energy curves with respect to variation in annealing atmosphere, confirming the variation in surface defects, which in turn affect photocatalytic degradation. The vacuum-annealed sample showed superior photocatalytic degradation efficiency as it had relatively higher pseudo-first order rate constants (k) of 0.009/min.

  20. TiO2 Nanotubes with Open Channels as Deactivation-Resistant Photocatalyst for the Degradation of Volatile Organic Compounds.

    PubMed

    Weon, Seunghyun; Choi, Wonyong

    2016-03-01

    We synthesized ordered TiO2 nanotubes (TNT) and compared their photocatalytic activity with that of TiO2 nanoparticles (TNP) film during the repeated cycles of photocatalytic degradation of gaseous toluene and acetaldehyde to test the durability of TNT as an air-purifying photocatalyst. The photocatalytic activity of TNT showed only moderate reduction after the five cycles of toluene degradation, whereas TNP underwent rapid deactivation as the photocatalysis cycles were repeated. Dynamic SIMS analysis showed that carbonaceous deposits were formed on the surface of TNP during the photocatalytic degradation of toluene, which implies that the photocatalyst deactivation should be ascribed to the accumulation of recalcitrant degradation intermediates (carbonaceous residues). In more oxidizing atmosphere (100% O2 under which less carbonaceous residues should form), the photocatalytic activity of TNP still decreased with repeating cycles of toluene degradation, whereas TNT showed no sign of deactivation. Because TNT has a highly ordered open channel structure, O2 molecules can be more easily supplied to the active sites with less mass transfer limitation, which subsequently hinders the accumulation of carbonaceous residues on TNT surface. Contrary to the case of toluene degradation, both TNT and TNP did not exhibit any significant deactivation during the photocatalytic degradation of acetaldehyde, because the generation of recalcitrant intermediates from acetaldehyde degradation is insignificant. The structural characteristics of TNT is highly advantageous in preventing the catalyst deactivation during the photocatalytic degradation of aromatic compounds.

  1. Fabrication and characterization of novel composite membranes composed of photonic crystals and TiO2 nanotube array films

    NASA Astrophysics Data System (ADS)

    Tang, Junjie; Zhu, Huili; Wang, Aijun; Chen, Sheng-Li; Yuan, Yao

    2016-05-01

    Novel composite membranes composed of photonic crystals (PCs) and TiO2 nanotube array (TNA) films have been fabricated by combining the room temperature floating self-assembly (RTFSA) method, recently developed by our research group, and the liquid-phase deposition technique. By applying this combined procedure, polystyrene (PS) opal PC/TNA and TiO2 inverse opal PC/TNA composite membranes were prepared. Scanning electron microscopy and ultraviolet/visible spectroscopy analyses showed that the membrane samples possessed very high crystalline quality. Notably, the ordered packing of the PS microspheres from the top to the bottom of the opal PC film was not affected by the surface roughness of the porous TNA substrate. This is attributed to the self-assembly mechanism of the colloidal particles, which produces a three-dimensional ordered structure in the RTFSA method. Herein, the crystallization of the colloidal particles occurred at the surface of the colloidal suspension, and the crystal growth proceeded downward from the surface of the suspension to the substrate.

  2. Graphene-modified TiO2 nanotube arrays as an adsorbent in micro-solid phase extraction for determination of carbamate pesticides in water samples.

    PubMed

    Zhou, Qingxiang; Fang, Zhi

    2015-04-15

    Graphene is a good adsorbent for organic pollutants, especially for compounds containing benzene rings. When used in TiO2 nanotube arrays for micro-solid phase extraction (μ-SPE), the combination of graphene's strong adsorptive properties with its good separation capabilities results in excellent sample preconcentration performance. In the present study, graphene-modified TiO2 nanotube arrays were prepared by electrodeposition using a cyclic voltammetric reduction method. Four carbamate pesticides, including metolcarb, carbaryl, isoprocarb, and diethofencarb, were used as model analytes to validate the enrichment properties of the prepared adsorbent in μ-SPE. Factors affecting the enrichment efficiency of the μ-SPE procedure were optimized and included sample pH, elution solvents, salting-out effect, adsorption time and desorption time. Under optimal conditions, graphene-modified TiO2 nanotube arrays exhibited excellent enrichment efficiency for carbamate pesticides. The detection limits of these carbamate pesticides ranged from 2.27 to 3.26 μg L(-1). The proposed method was validated using four environmental water samples, and yields of pesticides recovered from spiked test samples of the four analytes were in the range of 83.9-108.8%. These results indicate that graphene-modified TiO2 nanotube arrays exhibit good adsorption to the target pollutants, and the method described in this work could be used as a faster and easier alternative procedure for routine analysis of carbamate pesticides in real water samples.

  3. Photoelectrochemical aptasensor for the sensitive and selective detection of kanamycin based on Au nanoparticle functionalized self-doped TiO2 nanotube arrays.

    PubMed

    Xin, Yanmei; Li, Zhenzhen; Zhang, Zhonghai

    2015-11-04

    In this communication, a new photoelectrochemical aptasensor with Au nanoparticle functionalized self-doped TiO2 nanotube arrays (Au/SD-TiO2 NTs) as the core sensing unit and aptamers as the recognition unit was set up to accomplish the sensitive and selective detection of kanamycin with the lowest detection limit of 0.1 nM.

  4. Effect of dye-sensitized solar cells based on the anodizing TiO2 nanotube array/nanoparticle double-layer electrode

    NASA Astrophysics Data System (ADS)

    Yang, Jun Hyuk; Wung Bark, Chung; Kim, Kyung Hwan; Choi, Hyung Wook

    2014-11-01

    Highly ordered TiO2 nanotube arrays fabricated by anodization are very attractive for dye-sensitized solar cells owing to their superior charge percolation and slower charge recombination. Highly ordered, vertically aligned TiO2 nanotube arrays have been prepared by a three-step anodic oxidation. In this work, we considered the aforementioned strategies to improve the efficiency of dye-sensitized solar cells. Employing one of these approaches, the use of oxide semiconductors in the form of a TiO2 nanotube array was attempted as a novel means of improving the electron transport through the film. We fabricated a novel TiO2 nanoparticle/TiO2 nanotube array double-layer photoelectrode by a layer-by-layer assembly process, and we thoroughly investigated the effect of various structures on sample efficiency. Dye-sensitized solar cells with a light-to-electric energy conversion efficiency of 5.48% were achieved at a simulated solar light irradiation of 100 mW/cm2 (AM 1.5).

  5. Transfer and assembly of large area TiO2 nanotube arrays onto conductive glass for dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Li, Siqian; Ding, Hao; Li, Quantong; Wang, Baoyuan; Wang, Xina; Wang, Hao

    2014-02-01

    Highly ordered titanium oxide nanotube arrays are synthesized by a two-step anodic oxidation of pure titanium foil at constant voltage. It is found that the length of nanotube arrays firstly increased rapidly with the anodization time, and then the growth rate gradually slowed down with further increasing the anodization time. The mechanism of anodization time-dependent tube length growth is discussed. Large area free-standing TiO2 nanotube (TNT) arrays are detached from the underlying Ti foil and transferred onto the fluorine-doped tin oxide (FTO) conductive glass substrates to serve as the photoanodes of the dye-sensitized solar cells (DSSCs). The photoelectric performance of the DSSCs assembled by TNT/FTO films is strongly related to the tube length of titania and the surface treatment. For the photoanodes without any surface modification, the highest overall photovoltaic conversion efficiency (PCE) that can be achieved is 4.12% in the DSSC assembled with 33-μm-thick TNT arrays, while the overall PCE of DSSC based on the 33-μm-thick TNT arrays increases to 9.02% in response to the treatment with TiCl4.

  6. The Effect of the Electrodes Area Ratio on TiO2 Nanotube Arrays Yield in Anodization

    NASA Astrophysics Data System (ADS)

    He, Yun-Bing; Zhang, Wei-Cai; Mo, Xiao-Yan; Yu, Tao-Ran; Fan, Hong-Bo

    2016-05-01

    The anodization with different cathodes (i.e., point cathode, linear cathode or planar cathodes with different areas) was performed to determine the effect of the cathode area on TiO2 nanotube (TiNT) yield. Results show that proper planar cathode, but not point or linear cathode, is necessary for the production of TiNT, and 8:3 (S(-)/S(+)) is regarded as the optimal electrode area ratio. The anodization with three electrodes would help to further enhance the unit yield. And the unit yield by one cathode and two anodes is higher than that by two cathodes and one anode, but the product of the latter featured with more uniform structure. Our work would help in guiding the further exploration of high yield TiNT.

  7. Optimization of conditions for hydrogen production from anodized TiO2 nanotube-based photoelectrochemical cells.

    PubMed

    Hong, Won Sung; Park, Jong Hyeok; Han, Gui Young

    2009-12-01

    The photocatalytic splitting of water into H2 and O2 using semiconductors has received much attention, especially in terms of its potential application to the direct production of H2 as a clean energy source. In this study, the H2 yield increased with increasing reactor temperature, but the TiO2 nanotube arrays collapsed after prolonged operation at temperatures over 75 degrees C. We found that aqueous Na2SO3 reagent was the best hole scavenger of the different aqueous solutions examined. Using the optimum temperatures and electrolytes, we conducted an experiment to produce H2 from solutions with different pH values, and found that acidic conditions were better in terms of the amount of H2 produced. The results obtained allowed us to identify the optimal temperature, electrolyte and pH conditions required to produce H2 by photochemically splitting water.

  8. TiO2 nanotube sensor for online chemical oxygen demand determination in conjunction with flow injection technique.

    PubMed

    Li, Xuejin; Yin, Weiping; Li, Jianyong; Bai, Jing; Huang, Ke; Li, Jinhua; Zhou, Baoxue

    2014-06-01

    A simple, rapid and environmental friendly online chemical oxygen demand (COD) analytical method based on TiO2 nanotube sensor in conjunction with the flow injection technique was proposed to determine the COD of aqueous samples, especially for refractory organics, low-concentration wastewater, and surface water. The new method can overcome the drawbacks of the conventional COD determination methods. The results show that with the new method, each analysis takes only about 1 to 3 min, the linear range is up to 1 to 500 mg x L(-1) of the compound of interest, and the detection limit is 1 mg x L(-1). The COD values obtained by the proposed method are more accurate than those obtained by the conventional method.

  9. Aperiodic TiO2 nanotube photonic crystal: full-visible-spectrum solar light harvesting in photovoltaic devices.

    PubMed

    Guo, Min; Xie, Keyu; Wang, Yu; Zhou, Limin; Huang, Haitao

    2014-09-23

    Bandgap engineering of a photonic crystal is highly desirable for photon management in photonic sensors and devices. Aperiodic photonic crystals (APCs) can provide unprecedented opportunities for much more versatile photon management, due to increased degrees of freedom in the design and the unique properties brought about by the aperiodic structures as compared to their periodic counterparts. However, many efforts still remain on conceptual approaches, practical achievements in APCs are rarely reported due to the difficulties in fabrication. Here, we report a simple but highly controllable current-pulse anodization process to design and fabricate TiO2 nanotube APCs. By coupling an APC into the photoanode of a dye-sensitized solar cell, we demonstrate the concept of using APC to achieve nearly full-visible-spectrum light harvesting, as evidenced by both experimental and simulated results. It is anticipated that this work will lead to more fruitful practical applications of APCs in high-efficiency photovoltaics, sensors and optoelectronic devices.

  10. Transient competition between photocatalysis and carrier recombination in TiO2 nanotube film loaded with Au nanoparticles

    NASA Astrophysics Data System (ADS)

    Shao, Zhu-Feng; Yang, Yan-Qiang; Liu, Shu-Tian; Wang, Qiang

    2014-09-01

    Highly ordered TiO2 nanotube array (TNA) films are fabricated by using an anodic oxidation method. Au nanoparticles (NPs) films are decorated onto the top of TNA films with the aid of ion-sputtering and thermal annealing. An enhanced photocatalytic activity under ultraviolet C (UVC, 266 nm) light irradiation is obtained compared with that of the pristine TNA, which is shown by the steady-state photoluminescence (PL) spectra. Furthermore, a distinct blue shift in the nanosecond time-resolved transient photoluminescence (NTRT-PL) spectra is observed. Such a phenomenon could be well explained by considering the competition between the surface photocatalytic process and the recombination of the photo-generated carriers. The enhanced UV photocatalytic activities of the Au—TNA composite are evaluated through photo-degradation of methyl orange (MO) in an aqueous solution with ultraviolet—visible absorption spectrometry. Our current work may provide a simple strategy to synthesize defect-related composite photocatalytic devices.

  11. Alumina decorated TiO2 nanotubes with ordered mesoporous walls as high sensitivity NO(x) gas sensors at room temperature.

    PubMed

    Lü, Renjiang; Zhou, Wei; Shi, Keying; Yang, Ying; Wang, Lei; Pan, Kai; Tian, Chungui; Ren, Zhiyu; Fu, Honggang

    2013-09-21

    Alumina (Al2O3) decorated anatase TiO2 nanotubes with ordered mesoporous pore walls (Al2O3/meso-TiO2 nanotubes) are successfully synthesized through vacuum pressure induction technology, and then combined with the thermal decomposition of a mesoporous TiO2 sol precursor, inside the cylindrical nanochannels of an anodic aluminium oxide (AAO) template. The decorated Al2O3 was formed by in situ deposition via direct reaction of the strong acid sol precursor and the nanochannel wall of the AAO template. The resultant Al2O3/meso-TiO2 nanotubes are characterized in detail by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and N2 adsorption-desorption. The experimental results reveal that the Al2O3/meso-TiO2 nanotubes have a tubular structure with an average diameter of ∼200 nm and highly ordered mesopores in the tubular walls. The Al2O3 is distributed evenly on the anatase TiO2 nanotubes. Moreover, the Al2O3/meso-TiO2 nanotubes possess a large specific surface area (136 m(2) g(-1)) and narrow mesopore size distribution (∼10 nm). By using NO(x) as a probe molecule, the Al2O3/meso-TiO2 nanotube films exhibit better sensing performance than that of mesoporous TiO2 nanotubes, in terms of their high sensitivity, fast response-recovery time, and good stability in air at room temperature. The outstanding performance in the gas sensing ability of Al2O3/meso-TiO2 nanotubes is a result of their one-dimensional tubular and mesoporous nanostructures, advantageous for the adsorption and diffusion of NO(x) gas. In addition, the sensing response is greatly improved by virtue of the decorated Al2O3 on the surfaces of the TiO2 nanotubes, which acts as an energy barrier to suppress charge recombination. The structural properties of the Al2O3/meso-TiO2 nanotubes makes them a viable novel gas sensor material at room temperature.

  12. In situ plasmonic Ag nanoparticle anchored TiO2 nanotube arrays as visible-light-driven photocatalysts for enhanced water splitting

    NASA Astrophysics Data System (ADS)

    Ge, Ming-Zheng; Cao, Chun-Yan; Li, Shu-Hui; Tang, Yu-Xin; Wang, Lu-Ning; Qi, Ning; Huang, Jian-Ying; Zhang, Ke-Qin; Al-Deyab, S. S.; Lai, Yue-Kun

    2016-02-01

    An ultrasonication-assisted in situ deposition strategy was utilised to uniformly decorate plasmonic Ag nanoparticles on vertically aligned TiO2 nanotube arrays (NTAs) to construct a Ag@TiO2 NTA composite. The Ag nanoparticles act as efficient surface plasmon resonance (SPR) photosensitizers to drive photocatalytic water splitting under visible light irradiation. The Ag nanoparticles were uniformly deposited on the surface and inside the highly oriented TiO2 nanotubes. The visible-light-driven hydrogen production activities of silver nanoparticle anchored TiO2 nanotube array photocatalysts were evaluated using methanol as a sacrificial reagent in water under a 500 W Xe lamp with a UV light cutoff filter (λ >= 420 nm). It was found that the hydrogen production rate of the Ag@TiO2 NTAs prepared with ultrasonication-assisted deposition for 5 min was approximately 15 times higher than that of its pristine TiO2 NTAs counterpart. The highly efficient photocatalytic hydrogen evolution is attributed to the SPR effect of Ag for enhanced visible light absorption and boosting the photogenerated electron-hole separation/transfer. This strategy is promising for the design and construction of high efficiency TiO2 based photocatalysts for solar energy conversion.An ultrasonication-assisted in situ deposition strategy was utilised to uniformly decorate plasmonic Ag nanoparticles on vertically aligned TiO2 nanotube arrays (NTAs) to construct a Ag@TiO2 NTA composite. The Ag nanoparticles act as efficient surface plasmon resonance (SPR) photosensitizers to drive photocatalytic water splitting under visible light irradiation. The Ag nanoparticles were uniformly deposited on the surface and inside the highly oriented TiO2 nanotubes. The visible-light-driven hydrogen production activities of silver nanoparticle anchored TiO2 nanotube array photocatalysts were evaluated using methanol as a sacrificial reagent in water under a 500 W Xe lamp with a UV light cutoff filter (λ >= 420 nm

  13. Cobalt-Nickel Layered Double Hydroxides Modified on TiO2 Nanotube Arrays for Highly Efficient and Stable PEC Water Splitting.

    PubMed

    Chen, Weijian; Wang, Taotao; Xue, Jiawei; Li, Shikuo; Wang, Zidan; Sun, Song

    2017-03-01

    TiO2 -based photoanodes have attracted extensive attention worldwide for photoelectrochemical (PEC) water splitting, but these materials still suffer from poor electron-hole separation and low photoconversion efficiency. Here, the high PEC water splitting activity and long-term stability against photocorrosion of well-aligned hierarchical TiO2 @CoNi-layered double hydroxides nanotube arrays (TiO2 @CoNi-LDHs NTAs) are reported. The typical TiO2 @CoNi-LDHs NTAs exhibits enhancing photocurrent density of 4.4 mA cm(-2) at a potential of 1.23 V (vs reversible hydrogen electrode) under AM 1.5G simulated sunlight (100 mW cm(-2) ), 3.3 times higher than that of the pristine TiO2 sample. Moreover, this hierarchical electrode displays excellent stability against photocorrosion with initial activity loss no more than 1.0% even after 10 h irradiation in Na2 SO4 electrolyte solution (pH 6.8), much competitive to those reported TiO2 -based photoelectrodes. This work may offer a combinatorial synthesis strategy for the preparation of hierarchical architectures with high PEC performances.

  14. Influence of various sterilization procedures on TiO2 nanotubes used for biomedical devices.

    PubMed

    Junkar, Ita; Kulkarni, Mukta; Drašler, Barbara; Rugelj, Neža; Mazare, Anca; Flašker, Ajda; Drobne, Damjana; Humpolíček, Petr; Resnik, Matic; Schmuki, Patrik; Mozetič, Miran; Iglič, Aleš

    2016-06-01

    Sterilization is the final surface treatment procedure of all implantable devices and is one of the key factors which have to be considered before implementation. Since different sterilization procedures for all implantable devices influence mechanical properties as well as biological response, the influence of different sterilization techniques on titanium nanotubes was studied. Commonly used sterilization techniques such as autoclaving, ultra-violet light sterilization, hydrogen peroxide plasma sterilization as well as the not so frequently used gaseous oxygen plasma sterilization were used. Three different nanotube diameters; 15 nm, 50 nm and 100 nm were employed to study the effects of various sterilization techniques. It was observed that autoclave sterilization resulted in destruction of nanotubular features on all three studied nanotube diameters, while UV-light and both kinds of plasma sterilization did not cause any significant morphological changes on the surfaces. Differences between the sterilization techniques employed influenced cytocompatibility, especially in the case of nanotubes with 100 nm diameter.

  15. TiO2 nanotube arrays for photocatalysis: Effects of crystallinity, local order, and electronic structure

    DOE PAGES

    Liu, Jing; Hosseinpour, Pegah M.; Luo, Si; ...

    2014-11-19

    To furnish insight into correlations of electronic and local structure and photoactivity, arrays of short and long TiO₂ nanotubes were synthesized by electrochemical anodization of Ti foil, followed by thermal treatment in O₂ (oxidizing), Ar (inert), and H₂ (reducing) environments. The physical and electronic structures of these nanotubes were probed with x-ray diffraction, scanning electron microscopy, and synchrotron-based x-ray absorption spectroscopy, and correlated with their photocatalytic properties. The photocatalytic activity of the nanotubes was evaluated by monitoring the degradation of methyl orange under UV-VIS light irradiation. Results show that upon annealing at 350 °C all as-anodized amorphous TiO₂ nanotube samplesmore » partially transform to the anatase structure, with variations in the degree of crystallinity and in the concentration of local defects near the nanotubes' surface (~5 nm) depending on the annealing conditions. Degradation of methyl orange was not detectable for the as-anodized TiO₂ nanotubes regardless of their length. The annealed long nanotubes demonstrated detectable catalytic activity, which was more significant with the H₂-annealed nanotubes than with the Ar- and O₂-annealed nanotube samples. This enhanced photocatalytic response of the H₂-annealed long nanotubes relative to the other samples is positively correlated with the presence of a larger concentration of lattice defects (such as Ti3+ and anticipated oxygen vacancies) and a slightly lower degree of crystallinity near the nanotube surface. These physical and electronic structural attributes impact the efficacy of visible light absorption; moreover, the increased concentration of surface defects is postulated to promote the generation of hydroxyl radicals and thus accelerate the photodegradation of the methyl orange. The information obtained from this study provides unique insight into the role of the near-surface electronic and defect structure

  16. Removing structural disorder from oriented TiO2 nanotube arrays: reducing the dimensionality of transport and recombination in dye-sensitized solar cells.

    PubMed

    Zhu, Kai; Vinzant, Todd B; Neale, Nathan R; Frank, Arthur J

    2007-12-01

    We report on the influence of morphological disorder, arising from bundling of nanotubes (NTs) and microcracks in films of oriented TiO2 NT arrays, on charge transport and recombination in dye-sensitized solar cells (DSSCs). Capillary stress created during evaporation of liquids from the mesopores of dense TiO2 NT arrays was of sufficient magnitude to induce bundling and microcrack formation. The average lateral deflection of the NTs in the bundles increased with the surface tension of the liquids and with the film thicknesses. The supercritical CO2 drying technique was used to produce bundle-free and crack-free NT films. Charge transport and recombination properties of sensitized films were studied by frequency-resolved modulated photocurrent/photovoltage spectroscopies. Transport became significantly faster with decreased clustering of the NTs, indicating that bundling creates additional pathways via intertube contacts. Removing such contacts alters the transport mechanism from a combination of one and three dimensions to the expected one dimension and shortens the electron-transport pathway. Reducing intertube contacts also resulted in a lower density of surface recombination centers by minimizing distortion-induced surface defects in bundled NTs. A causal connection between transport and recombination is observed. The dye coverage was greater in the more aligned NT arrays, suggesting that reducing intertube contacts increases the internal surface area of the films accessible to dye molecules. The solar conversion efficiency and photocurrent density were highest for DSSCs incorporating films with more aligned NT arrays owing to an enhanced light-harvesting efficiency. Removing structural disorder from other materials and devices consisting of nominally one-dimensional architectures (e.g., nanowire arrays) should produce similar effects.

  17. Enhanced photocatalytic degradation of humic acids using Al and Fe co-doped TiO2 nanotubes under UV/ozonation for drinking water purification.

    PubMed

    Yuan, Rongfang; Zhou, Beihai; Hua, Duo; Shi, Chunhong

    2013-11-15

    O3/UV/TiO2 was used to effectively decompose humic acids (HAs) in drinking water. To obtain a large specific surface area and low band gap energy, Al and Fe co-doped TiO2 nanotubes were successfully synthesized using the hydrothermal method. The effect of the optimal co-doped TiO2 nanotubes catalyst on the HAs removal efficiency through O3/UV/co-doped TiO2 process was investigated. The highest HAs removal efficiency (79.4%) that exhibited a pseudo-first-order rate constant of 0.172 min(-1) was achieved, in the presence of 550 °C calcined 1.0% co-doped TiO2 nanotubes with an Al:Fe ratio of 0.25:0.75. The effects of calcination temperature and doping concentration on anatase phase weight fractions, average crystallite sizes, Brunauer-Emmett-Teller surface area, catalyst band gap energy, and catalyst photocatalytic activity were also discussed. The inorganic anions also affected the catalyst photocatalytic ability. In a neutral solution, SO4(2-) slightly promoted HAs removal. However, HCO3(-) was found to significantly inhibit the catalyst activity, whereas Cl(-) had negligible effect on photocatalytic ability.

  18. SaOS-2 cell response to macro-porous boron-incorporated TiO2 coating prepared by micro-arc oxidation on titanium.

    PubMed

    Huang, Qianli; Elkhooly, Tarek A; Liu, Xujie; Zhang, Ranran; Yang, Xing; Shen, Zhijian; Feng, Qingling

    2016-10-01

    The aims of the present study were to develop boron-incorporated TiO2 coating (B-TiO2 coating) through micro-arc oxidation (MAO) and subsequently evaluate the effect of boron incorporation on the in vitro biological performance of the coatings. The physicochemical properties of B-TiO2 coating and its response to osteoblast like cells (SaOS-2) were investigated compared to the control group without boron (TiO2 coating). The morphological and X-ray diffraction results showed that both coatings exhibited similar surface topography and phase composition, respectively. However, the incorporation of B led to an enhancement in the surface hydrophilicity of B-TiO2 coating. The spreading of SaOS-2 cells on B-TiO2 coating was faster than that on TiO2 coating. The proliferation rate of SaOS-2 cells cultured on B-TiO2 decreased after 5days of culture compared to that on TiO2 coating. SaOS-2 cells cultured on B-TiO2 coating exhibited an enhanced alkaline phosphatase (ALP) activity, Collagen I synthesis and in vitro mineralization compared to those on TiO2 coating. The present findings suggest that B-TiO2 coating is a promising candidate surface for orthopedic implants.

  19. Silver nanoparticles decorated anatase TiO2₂nanotubes for removal of pentachlorophenol from water.

    PubMed

    Yu, Lian; Yang, Xiaofang; Ye, Yushi; Peng, Xianjia; Wang, Dongsheng

    2015-09-01

    One-dimensional nanotubes are promising materials for environmental applications. In this study, anatase TiO2 nanotubes (TNTs) were fabricated using an alkaline hydrothermal method at 130°C and then calcinated at 400°C for 2h. Ag nanoparticles were photo-deposited onto the TNTs for enhanced photodegradation of pentachlorophenol (PCP) under simulated solar light. The samples were characterized using transmission electron microscopy, physical adsorption of nitrogen, X-ray diffraction, X-ray photoelectron spectroscopy and UV-Visible diffuse reflectance spectroscopic techniques. The as-synthesized TNTs showed tubular structures with the outer and inner diameter of 9-10 and 5-6 nm, respectively. The results showed that metallic Ag nanoparticles were uniformly dispersed on the TNTs surface, and Ag/TNTs exhibited significant visible-light absorption. After 180 min irradiation, about 99% PCP was removed by Ag/TNTs (5.4 at.%), compared to 54.3% by P25 and 59.4% by pure TNTs. This is attributed to the synergistic effects between Ag nanoparticles acting as traps to effectively capture the photo-generated electrons, and the localized surface plasmon resonance (LSPR) of Ag nanoparticles promoting the absorption of visible light. The intermediates during the PCP photodegradation were systematically analyzed, ruling out the existence of high toxic polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans. Ag/TNTs showed excellent stability even after five cycles.

  20. TiO2 thin films with rutile phase prepared by DC magnetron co-sputtering at room temperature: Effect of Cu incorporation

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Li, Yujie; Ba, Xin; Huang, Lin; Yu, Ying

    2015-08-01

    The thin films for pure TiO2 and that incorporated with Cu ion were deposited by DC magnetron co-sputtering with Ar gas. The crystal texture, surface morphology, energy gap and optical properties of the prepared films have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectrometer (XPS), UV-vis spectrophotometer, and Raman spectroscopy. The results show that as-deposited TiO2 film mainly possesses anatase structure at room temperature with pure Ar gas, but the introduction of Cu can alter the phase structure of crystallite TiO2. XRD patterns and Raman spectra indicate that the Cu incorporation with high concentration (ACu/ATi + ACu ≈ 20%) favors the formation of rutile phase. Moreover, the Cu incorporation into TiO2 lattice induces band gap narrowing. Band structures and density of states have been analyzed based on density functional theory (DFT) and periodic models in order to investigate the influence of the Cu incorporation on the electronic structure of TiO2. Both experimental data and electronic structure calculations evidence the fact that the change in film structure from the anatase to the rutile phase can be ascribed to the possible incorporation of Cu1+ in the sites previously occupied by Ti4+, and the presence of Cu results in important effect on the electronic states, which is mainly related to the 3d Cu orbitals in the gap and in the vicinity of the valence band edges for TiO2.

  1. 3D silk fibroin scaffold incorporating titanium dioxide (TiO2) nanoparticle (NPs) for tissue engineering.

    PubMed

    Kim, Jung-Ho; Sheikh, Faheem A; Ju, Hyung Woo; Park, Hyun Jung; Moon, Bo Mi; Lee, Ok Joo; Park, Chan Hum

    2014-07-01

    The present study deals with fabrication of scaffolds composing of silk fibroin and TiO2 NPs fabricated using a salt-leaching process. At first instance, the TiO2 NPs were prepared by using sol-gel synthesis, affording to have average diameter of 77±21μm. Furthermore, the aqueous solutions of silk fibroin were mixed with 0.2%, 2.0% and 4.0% of TiO2 NPs and salt-leaching process was introduced which resulted in creation of porous scaffolds modified with TiO2 NPs. The presence of TiO2 NPs in scaffolds was confirmed by VP-FE-SEM-EDS, TGA and XRD. The presence of TiO2 NPs influenced in decrease in pore size and swelling behavior of composite scaffolds. The resultant mechanical property of scaffolds was improved upon the introduction of TiO2 NPs. Moreover, cell cytotoxicity results for 1, 3 and 7 days; revealed no toxic behavior to osteoblasts. However, a mild toxicity to NIH 3T3 fibroblasts was observed with the scaffolds containing 4.0% TiO2 NPs. The cell fixation results from 1 and 7 days of incubation indicated the attachment, spreading and subsequent proliferation of fibroblasts. However, these findings were independent to the amount of TiO2 NPs in scaffolds.

  2. Surface and sorption properties of TIO2 nanotubes, synthesized by electrochemical anodization

    NASA Astrophysics Data System (ADS)

    Serikov, T. M.; Ibrayev, N. Kh; Smagulov, Zh

    2016-02-01

    Electrochemical anodizing of titanium metal in the fluorine-containing electrolyte was used for production of nanotubes of titanium dioxide. The surface morphology of the films was investigated by scanning electron microscopy. It was found that with increasing anodizing voltage the inner diameter, growth rate and nanotubes interporous distance is increasing. The distribution of pore volume studied by the method of adsorption and desorption of nitrogen. The specific surface area of titanium dioxide films was measured for determine the conditions of anodizing on their changes. The sorption capacity of the films was studied.

  3. TiO2 nanotubes as alternative cathode in microbial fuel cells: Effect of annealing treatment on its performance

    NASA Astrophysics Data System (ADS)

    Yahia, S. Ait Ali; Hamadou, L.; Salar-García, M. J.; Kadri, A.; Ortiz-Martínez, V. M.; Hernández-Fernández, F. J.; de los Rios, A. Pérez; Benbrahim, N.

    2016-11-01

    In the present work, amorphous and crystalline TiO2 nanotubes (TiNT) were fabricated via anodization and characterized as an alternative cathode for Microbial Fuel Cells (MFCs). The morphology of TiNT is characterized by scanning electron microscopy (SEM). The crystalline structure and chemical composition are examined by X-ray diffraction (XRD) and Energy dispersive X-ray spectroscopy (EDX). The electrical conductivity characteristics were examined by electrochemical impedance spectroscopy (EIS). MFCs based on the alternative cathodes were evaluated in terms of energy generation and wastewater treatment. The performances of the as-anodized nanotubes and TiNT annealed at 450 °C and at 550 °C were investigated in double-chamber MFCs with carbon rod and graphite granules as anode and polymer inclusion membrane based on ionic liquid as separator. Industrial wastewater was the source of carbon and inoculum for the experiments. The as grown amorphous nanotubes exhibited the best output power density of 15.16 mWm-2. The results reported here indicate that the specific surface area and the oxygen vacancies of the TiNT cathode can influence the MFCs performance together, because both factors play crucial role in the oxygen reduction reaction (ORR). As-anodized TiNT, due to its higher specific surface provide more active sites for electrode reactions. The final oxygen demand (COD) for all systems achieved a COD removal within the interval 54-71% after 10 days. This approved the suitability of MFCs for wastewater treatment.

  4. TiO2 nanotubes with ultrathin walls for enhanced water splitting.

    PubMed

    Mohamed, Ahmad M; Aljaber, Amina S; AlQaradawi, Siham Y; Allam, Nageh K

    2015-08-14

    We demonstrate, for the first time, the synthesis of titania nanotubes with ultrathin (3-5 nm) wall thickness. As revealed by the incident photon-to-current collection efficiency (IPCE) and electrochemical impedance spectroscopy measurements, the ultrathin walls, less than the charge carrier diffusion length, were essential to ensure fast and efficient charge carrier collection.

  5. Thin layer of ordered boron-doped TiO2 nanotubes fabricated in a novel type of electrolyte and characterized by remarkably improved photoactivity

    NASA Astrophysics Data System (ADS)

    Siuzdak, Katarzyna; Szkoda, Mariusz; Lisowska-Oleksiak, Anna; Grochowska, Katarzyna; Karczewski, Jakub; Ryl, Jacek

    2015-12-01

    This paper reports a novel method of boron doped titania nanotube arrays preparation by electrochemical anodization in electrolyte containing boron precursor - boron trifluoride diethyl etherate (BF3 C4H10O), simultaneously acting as an anodizing agent. A pure, ordered TiO2 nanotubes array, as a reference sample, was also prepared in solution containing a standard etching compound: ammonium fluoride. The doped and pure titania were characterized by scanning electron microscopy, UV-vis spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, photoluminescence emission spectroscopy and by means of electrochemical methods. The B-doping decidedly shifts the absorption edge of TiO2 nanotubes towards the visible light region and significantly inhibits the radiative recombination processes. Despite the fact that the doped sample is characterized by 4.6 lower real surface area when compared to pure titania, it leads to the decomposition of methylene blue in 93%, that is over 2.3 times higher than the degradation efficiency exhibited by the undoped material. The formation rate of hydroxyl radicals (rad OH) upon illumination significantly favours boron doped titania as a photocatalytic material. Moreover, the simple doping of TiO2 nanotubes array results in the enhancement of generated photocurrent from 120 μA/cm2 to 350 μA/cm2 registered for undoped and doped electrode, respectively.

  6. Preparation of platinum- and silver-incorporated TiO2 coatings in thin-film photoreactor for the photocatalytic decomposition of o-cresol.

    PubMed

    Kuo, Yu-Lin; Su, Te-Li; Chuang, Kai-Jen; Chen, Hua-Wei; Kung, Fu-Chen

    2011-12-01

    Platinum-incorporated TiO2 (Pt-TiO2) and silver-incorporated TiO2 (Ag-TiO2) coatings on sapphire tubes of a thin-film photoreactor were prepared using a photoreduction process. Results of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) revealed that the Ag-TiO2 coatings consisted of a mixture of Ag2O, Ag and TiO2 particles, owing to the partial oxidization of silver particles on the TiO2 coatings, while the Pt-TiO2 coating contained a mixture of Pt and TiO2 particles. Diffuse reflectance UV-Vis spectra (DRS) showed that metal particles (Ag or Pt) incorporated into the TiO2 coatings promoted optical absorption in the visible region and made it possible for the coatings to be excited by visible light. Photoluminescence (PL) spectra showed that the PL intensity of the Pt-TiO2 coating was lower than that of the Ag-TiO2 and TiO2 coatings, indicating that the Pt-TiO2 coating had a higher efficiency of charge carrier trapping, immigration and transfer, which subsequently promoted the pseudo-first-order rate constants after the UV/TiO2 process. The Pt-TiO2 coatings for the photocatalytic decomposition of o-cresol under UV light irradiation corresponded to a higher pseudo-first-order rate constant (k) of 0.02 min(-1) when compared with the photocatalytic decomposition rates of pure TiO2 coatings (k = 0.0062 min(-1)) and Ag-TiO2 coatings (k = 0.01 min(-1)). The experimental results also indicated that the photodegradation rate of the Pt-TiO2 coating under visible light irradiation was significantly higher than the photodegradation rates of the Ag-TiO2 and pure TiO2 coatings.

  7. DFT Investigation on the Electronic and Water Adsorption Properties of Pristine and N-Doped TiO2 Nanotubes for Photocatalytic Water Splitting Applications

    NASA Astrophysics Data System (ADS)

    Enriquez, John Isaac G.; Moreno, Joaquin Lorenzo V.; David, Melanie Y.; Arboleda, Nelson B.; Lin, Ong Hui; Villagracia, Al Rey C.

    2017-02-01

    Experimental studies have shown the production of hydrogen through a photocatalytic water splitting process using a titanium dioxide nanotube (TiO2NT) as a photoelectrode. In this study, a theoretical model of pristine and nitrogen-doped TiO2NT based on a TiO2 anatase (101) surface is presented. Spin unrestricted density functional theory calculations were performed to provide a detailed description of the geometries, electronic properties, and adsorption of water (H2O) on pristine and N-doped TiO2NT. The calculations show that doping with N will improve the photocatalytic properties of TiO2NT in two ways: First, the energy barrier of the dissociation reaction of water into hydroxyl radical and hydrogen atom is reduced; and second, the defect-induced states above the valence band lowers the band gap which will result in enhanced visible-light-driven photoactivity. Based on the position of the Fermi level relative to the defect induced energy levels, an optimal doping concentration of around 1.4% is proposed, which is in good agreement with experimental results. This study provides an atomic/molecular level understanding of the photocatalytic water splitting process and may serve as a groundwork for the rational design of more efficient photocatalysts.

  8. Design and preparation of highly active carbon nanotube-supported sulfated TiO 2 and platinum catalysts for methanol electrooxidation

    NASA Astrophysics Data System (ADS)

    Song, Huanqiao; Xiao, Pu; Qiu, Xinping; Zhu, Wentao

    A novel electrocatalyst structure of carbon nanotube-supported sulfated TiO 2 and Pt (Pt-S-TiO 2/CNT) is reported. The Pt-S-TiO 2/CNT catalysts are prepared by a combination of improved sol-gel and ethylene glycol reduction methods. Transmission electron microscopy and X-ray diffraction show that the sulfated TiO 2 is amorphous and is coated uniformly on the surface of the CNTs. Pt nanoparticles of about 3.6 nm in size are homogenously dispersed on the sulfated TiO 2 surface. Fourier transform infrared spectroscopy analysis proves that the CNT surfaces are modified with sulfated TiO 2 and a high concentration of SO x, and adsorbed OH species exist on the surface of the sulfated TiO 2. Electrochemical studies are carried out using chronoamperometry, cyclic voltammetry, CO stripping voltammetry and impedance spectroscopy. The results indicate that Pt-S-TiO 2/CNT catalysts have much higher catalytic activity and CO tolerance for methanol electrooxidation than Pt/TiO 2/CNTs, Pt/CNTs and commercial Pt/C.

  9. TiO2 decorated Co3O4 acicular nanotube arrays and its application as a non-enzymatic glucose sensor.

    PubMed

    Gao, Zhenfei; Zhang, Liqiang; Ma, Chi; Zhou, Qidong; Tang, Yushu; Tu, Zhiqiang; Yang, Wang; Cui, Lishan; Li, Yongfeng

    2016-06-15

    TiO2 modified Co3O4 acicular nanotube arrays (ANTAs) have been fabricated in this study, showing a good performance in glucose detection. In the experiment, the precursor Co(CO3)0.5(OH)·0.11H2O acicular nanowire arrays (ANWAs) was first grown on the fluorine doped tin oxide (FTO) substrate by a hydrothermal method. Thereafter, the uniform pink precursor Co(CO3)0.5(OH)·0.11H2O ANWAs was completely converted to the black Co3O4 ANTAs thin film by alkaline treatment. After the decoration of TiO2, the TiO2/Co3O4 ANTAs electrode exhibits a much higher current response to glucose compared with the Co3O4 ANTAs. Importantly, this neotype composite structure of Co3O4 enhances the glucose sensing performance by increasing specific surface area, additional reactive sites and synergistic effect, which make the TiO2/Co3O4 glucose sensor show a high sensitivity of 2008.82 μA mM(-1) cm(-2), a fast response time (less than 5s) and a detection limit as low as 0.3396 μM (S/N=3). The TiO2/Co3O4 ANTAs modified electrode exhibits a high selectivity for glucose in human serum, against ascorbic acid and uric acid.

  10. New Approach to Create TiO2(B)/Carbon Core/Shell Nanotubes: Ideal Structure for Enhanced Lithium Ion Storage.

    PubMed

    Zhu, Xiaoyi; Yang, Xianfeng; Lv, Chunxiao; Guo, Shaojun; Li, Jianjiang; Zheng, Zhanfeng; Zhu, Huaiyong; Yang, Dongjiang

    2016-07-27

    To achieve uniform carbon coating on TiO2 nanomaterials, high temperature (>500 °C) annealing treatment is a necessity. However, the annealing treatment inevitably leads to the strong phase transformation from TiO2(B) with high lithium ion storage (LIS) capacity to anatase with low LIS one as well as the damage of nanostructures. Herein, we demonstrate a new approach to create TiO2(B)/carbon core/shell nanotubes (C@TBNTs) using a long-chain silane polymethylhydrosiloxane (PMHS) to bind the TBNTs by forming Si-O-Ti bonds. The key feature of this work is that the introduction of PMHS onto TBNTs can afford TBNTs with very high thermal stability at higher than 700 °C and inhibit the phase transformation from TiO2(B) to anatase. Such a high thermal property of PMHS-TBNTs makes them easily coated with highly graphitic carbon shell via CVD process at 700 °C. The as-prepared C@TBNTs deliver outstanding rate capability and electrochemical stability, i.e., reversible capacity above 250 mAh g(-1) at 10 C and a high specific capacity of 479.2 mAh g(-1) after 1000 cycles at 1 C. As far as we know, the LIS performance of our sample is the highest among the previously reported TiO2(B) anode materials.

  11. Enhanced photocatalytic activity of bismuth-doped TiO2 nanotubes under direct sunlight irradiation for degradation of Rhodamine B dye

    NASA Astrophysics Data System (ADS)

    Natarajan, Thillai Sivakumar; Natarajan, Kalithasan; Bajaj, Hari C.; Tayade, Rajesh J.

    2013-05-01

    Bismuth-doped TiO2 nanotubes (Bi-TNT) were successfully synthesized by combination of sol-gel and hydrothermal methods. The synthesized photocatalyst was efficiently used for degradation of rhodamine B (RhB) dye under direct sunlight irradiation. Subsequent characterization of synthesized photocatalysts was carried out using PXRD, SEM, TEM, EDX, FT-IR, Raman, N2 adsorption, TPD-NH3, UV-Vis DRS, XRF and ICP techniques. The surface area of the TiO2 nanoparticles increased after tubular structure formation (TiO2 nanoparticles—114.21 m2/g, TiO2 nanotube—191.93 m2/g). The degradation studies revealed that initial rate of photocatalytic degradation of RhB dye using Bi-TNT was 5.56, 4.16, 1.30 and 2.38 times higher as compared to TNP, Bi-TNP, TNT and Degussa P-25 TiO2 (P-25), respectively, under direct sunlight irradiation. The enhanced photocatalytic activity of Bi-TNT may be due to the increase in the surface area and Bi doping, which leads to effective separation of photogenerated carriers. The degradation was confirmed by chemical oxygen demand, total organic carbon and total inorganic carbon analysis of the degraded dye solutions. The probable degradation mechanism of RhB dye has also been proposed using liquid chromatography-mass spectrometry analysis of degraded samples.

  12. Highly ordered and vertically oriented TiO2/Al2O3 nanotube electrodes for application in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kim, Jae-Yup; Lee, Kyeong-Hwan; Shin, Junyoung; Park, Sun Ha; Kang, Jin Soo; Han, Kyu Seok; Sung, Myung Mo; Pinna, Nicola; Sung, Yung-Eun

    2014-12-01

    The surface of long TiO2 nanotube (NT) electrodes in dye-sensitized solar cells (DSSCs) was modified without post-annealing by using atomic layer deposition (ALD) for the enhancement of photovoltage. Vertically oriented TiO2 NT electrodes with highly ordered and crack-free surface structures over large areas were prepared by a two-step anodization method. The prepared TiO2 NTs had a pore size of 80 nm, and a length of 23 μm. Onto these TiO2 NTs, an Al2O3 shell of a precisely controlled thickness was deposited by ALD. The conformally coated shell layer was confirmed by high-resolution transmission electron microscopy, energy-dispersive x-ray spectroscopy, and x-ray photoelectron spectroscopy. The open-circuit voltage (Voc) of the DSSCs was gradually enhanced as the thickness of the Al2O3 shell of the TiO2/Al2O3 NT electrodes was increased, which resulted from the enhanced electron lifetime. The enhanced electron lifetime caused by the energy barrier effect of the shell layer was measured quantitatively by the open-circuit voltage decay technique. As a result, 1- and 2-cycle-coated samples showed enhanced conversion efficiencies compared to the bare sample.

  13. Enhanced Photoelectrochemical Activity of ZnO-Coated TiO2 Nanotubes and Its Dependence on ZnO Coating Thickness

    NASA Astrophysics Data System (ADS)

    Cai, Hua; Liang, Peipei; Hu, Zhigao; Shi, Liqun; Yang, Xu; Sun, Jian; Xu, Ning; Wu, Jiada

    2016-02-01

    One-dimensional heterogeneous nanostructures in the form of ZnO-coated TiO2 nanotubes (ZnO/TiO2 NTs) were fabricated by atomic layer deposition of an ultrathin ZnO coating on electrochemical anodization-formed TiO2 nanotubes (NTs) with the thickness of ZnO coating being precisely controlled at atomic scale, and the photoelectrochemical activity of the fabricated ZnO/TiO2 NTs and the influence of ZnO coating and its thickness were studied. The structures of TiO2 NTs and ZnO coatings were characterized by X-ray diffraction, Raman backscattering spectroscopy, and transmission electron microscopy. The photoelectrochemical activity was studied through the measurements of electrochemical impendence, flat-band potential, and transient photocurrent density. The TiO2 NTs exhibit anatase structure, and the ZnO coatings are structured with hexagonal wurtzite. The photoelectrochemical activity of the ZnO/TiO2 NTs is strongly dependent on the thickness of ZnO coating. ZnO/TiO2 NTs with a thinner rather than a thicker ZnO coating exhibit better photoelectrochemical activity with reduced charge transfer resistance, increased negative flat-band potentials, and enhanced photocurrent densities. Under visible illumination, an increase of about 60 % in the photoelectrochemical activity is obtained for ZnO/TiO2 NTs with an about 2-nm-thick ZnO coating.

  14. Enhanced Photoelectrochemical Activity of ZnO-Coated TiO2 Nanotubes and Its Dependence on ZnO Coating Thickness.

    PubMed

    Cai, Hua; Liang, Peipei; Hu, Zhigao; Shi, Liqun; Yang, Xu; Sun, Jian; Xu, Ning; Wu, Jiada

    2016-12-01

    One-dimensional heterogeneous nanostructures in the form of ZnO-coated TiO2 nanotubes (ZnO/TiO2 NTs) were fabricated by atomic layer deposition of an ultrathin ZnO coating on electrochemical anodization-formed TiO2 nanotubes (NTs) with the thickness of ZnO coating being precisely controlled at atomic scale, and the photoelectrochemical activity of the fabricated ZnO/TiO2 NTs and the influence of ZnO coating and its thickness were studied. The structures of TiO2 NTs and ZnO coatings were characterized by X-ray diffraction, Raman backscattering spectroscopy, and transmission electron microscopy. The photoelectrochemical activity was studied through the measurements of electrochemical impendence, flat-band potential, and transient photocurrent density. The TiO2 NTs exhibit anatase structure, and the ZnO coatings are structured with hexagonal wurtzite. The photoelectrochemical activity of the ZnO/TiO2 NTs is strongly dependent on the thickness of ZnO coating. ZnO/TiO2 NTs with a thinner rather than a thicker ZnO coating exhibit better photoelectrochemical activity with reduced charge transfer resistance, increased negative flat-band potentials, and enhanced photocurrent densities. Under visible illumination, an increase of about 60 % in the photoelectrochemical activity is obtained for ZnO/TiO2 NTs with an about 2-nm-thick ZnO coating.

  15. The effect of crystal structure of TiO2 nanotubes on the formation of calcium phosphate coatings during biomimetic deposition

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Kim, Sun; McLeod, John A.; Li, Jun; Guo, Xiaoxuan; Sham, Tsun-Kong; Liu, Lijia

    2017-02-01

    The crystallization process of bioactive calcium phosphate (CaP) species via biomimetic deposition onto anodic TiO2 nanotubes is investigated. The porous surface of nanostructured TiO2 provides an ideal substrate for CaP crystallization. The compositions of CaP coatings are studied using X-ray absorption near-edge structures (XANES) at the Ca K-edge. Using detection modes with different probing depths, both the surface of the CaP coating and the CaP-TiO2 interface are simultaneously analyzed. Calcium phosphate (CaP) species, such as hydroxyapatite (HAp), octacalcium phosphate (Ca8(HPO4)2(PO4)4·5H2O, OCP), brushite (CaHPO4·2H2O, DCPD), and amorphous calcium phosphate (ACP), are found in the CaP coatings. TiO2 nanotubes of amorphous and anatase phases are comparatively studied to determine their effect on the efficiency of CaP formation and the phase transformation among CaP species in prolonged deposition time. It is found the composition of CaP coating has a strong dependency on the crystal structure of TiO2 substrate and the kinetics (deposition time).

  16. Gas Sensitivity and Sensing Mechanism Studies on Au-Doped TiO2 Nanotube Arrays for Detecting SF6 Decomposed Components

    PubMed Central

    Zhang, Xiaoxing; Yu, Lei; Tie, Jing; Dong, Xingchen

    2014-01-01

    The analysis to SF6 decomposed component gases is an efficient diagnostic approach to detect the partial discharge in gas-insulated switchgear (GIS) for the purpose of accessing the operating state of power equipment. This paper applied the Au-doped TiO2 nanotube array sensor (Au-TiO2 NTAs) to detect SF6 decomposed components. The electrochemical constant potential method was adopted in the Au-TiO2 NTAs' fabrication, and a series of experiments were conducted to test the characteristic SF6 decomposed gases for a thorough investigation of sensing performances. The sensing characteristic curves of intrinsic and Au-doped TiO2 NTAs were compared to study the mechanism of the gas sensing response. The results indicated that the doped Au could change the TiO2 nanotube arrays' performances of gas sensing selectivity in SF6 decomposed components, as well as reducing the working temperature of TiO2 NTAs. PMID:25330053

  17. CdTe and graphene co-sensitized TiO2 nanotube array photoanodes for protection of 304SS under visible light.

    PubMed

    Li, Hong; Wang, Xiutong; Zhang, Liang; Hou, Baorong

    2015-04-17

    CdTe/graphene/TiO2 films that served as photoanodes for cathodic protection application were prepared by an electrochemical deposition method. The deposition of graphene and CdTe nanoparticles (NPs) on the surface of the TiO2 nanotubes was confirmed by scanning electron microscope and transmission electron microscopy. The composites exhibited high light absorption in both the UV and visible light region. The results indicated that TiO2 nanotube photoelectrodes sensitized by 20-cycle graphene and 30-cycle CdTe NPs exhibited effective photocathodic protection properties for 304 stainless steel (304SS) under the visible-light illumination, with an photopotential of -750 mV versus saturated calomel electrode and a current density of 560 μA cm(-2). Due to the efficient photogenerated charge separation, the three-component CdTe/graphene/TiO2 showed stronger photoresponse than pure TiO2 under visible-light illumination. In summary, the CdTe/graphene could improve the photocathodic protection properties of TiO2 films.

  18. Design of β-cyclodextrin modified TiO2 nanotubes for the adsorption of Cu(II): Isotherms and kinetics study.

    PubMed

    Triki, Mohamed; Tanazefti, Haythem; Kochkar, Hafedh

    2017-05-01

    This paper builds on previous literature showing the interesting adsorptive properties of TiO2 nanotubes. It further explores the positive effect of β-cyclodextrin on these properties. Hence, β-cyclodextrin modified TiO2 nanotubes were successfully prepared and characterized by XRD, N2 physisorption at 77K, Raman, FTIR-ATR, (1)H NMR, TEM and EPR. The adsorptive interaction of Cu(II) with materials was investigated in aqueous solution at pH 9.25 (NH4(+)/NH3). The main conclusion is that copper(II)-ammonia complexation equilibria play an important role in the adsorption process. The β-cyclodextrin was found to improve the Cu(NH3)4(2+) adsorption mainly by retarding its precipitation to high concentrations values (>400mgL(-1)). Adsorption experimental data showed good fit with the pseudo-second-order model and the Langmuir isotherm model.

  19. Synthesis and Characterization of TiO2 Nanotubes Sensitized with CdS Quantum Dots Using a One-Step Method

    NASA Astrophysics Data System (ADS)

    Song, Jiahui; Zhang, Xinguo; Zhou, Chunyan; Lan, Yuwei; Pang, Qi; Zhou, Liya

    2015-01-01

    A novel one-step synthesis process was used to assemble CdS quantum dots (QDs) into TiO2 nanotube arrays (TNTAs). The sensitization time of the TiO2 nanotubes can be adjusted by controlling the CdS QD synthesis time. The absorption band of sensitized TNTAs red-shifted and broadened to the visible spectrum. The photoelectric conversion efficiency increased to 0.83%, the open-circuit voltage to 776 mV, and the short-circuit current density ( J SC) to 2.30 mA cm-2 with increased sensitization time. The conversion efficiency with this new sensitization method was five times that of nonsensitized TNTAs, providing novel ideas for study of TNTA solar cells.

  20. Improved visible solar absorber based on TiO2 nanotube film by surface-loading of plasmonic Au nanoparticles

    NASA Astrophysics Data System (ADS)

    Shao, Zhufeng; Wang, Xinshun; Ren, Shoutian; Tian, Zhaoshuo; Fan, Shengli; Sun, Shengsheng; Liu, Shutian; Wang, Qiang

    2013-08-01

    Plasmon-driven electrons injection into active layers of optoelectronic devices is a promising and challenging research topic due to the great unavailability of suitable materials and devices configurations capable of providing comprehensively high photocurrent. In this letter, anodic TiO2 nanotubes array (TNA) films are formed to show enhanced visible light absorbing properties by surface-loading of isolated Au nanoparticles (NPs), exhibiting increased photocurrent and decreased response time. Surface Plasmon produces hot free electrons in the gold NPs when the device is illuminated by visible light with suitable photon energies, and the direct injection of hot electrons into TNA film is realized due to the energy nonequilibrium between gold NPs and TNA film. A significant fraction of these electrons will tunnel into the semiconductor's conduction band, which will introduce the surface n-type conduction layer, resulting in about 145% enhancement of photocurrent and 37% reduction of response time. A scattering-induced enhancement mechanism contributes effectively to the plasmonic photoresponse.

  1. Improved antibacterial activity and biocompatibility on vancomycin-loaded TiO2 nanotubes: in vivo and in vitro studies.

    PubMed

    Zhang, Hangzhou; Sun, Yu; Tian, Ang; Xue, Xiang Xin; Wang, Lin; Alquhali, Ali; Bai, Xizhuang

    2013-01-01

    The goal for current orthopedic implant research is to design implants that have not only good biocompatibility but also antibacterial properties. TiO2 nanotubes (NTs) were fabricated on the titanium surface through electrochemical anodization, which added new properties, such as enhanced biocompatibility and potential utility as drug nanoreservoirs. The aim of the present study was to investigate the antibacterial properties and biocompatibility of NTs loaded with vancomycin (NT-V), both in vitro and in vivo. Staphylococcus aureus was used to study the antibacterial properties of the NT-V. There were three study groups: the commercially pure titanium (Cp-Ti) group, the NT group (nonloaded vancomycin), and the NT-V group. We compared NT-V biocompatibility and antibacterial efficacy with those of the NT and Cp-Ti groups. Compared with Cp-Ti, NT-V showed good antibacterial effect both in vitro and in vivo. Although the NTs reduced the surface bacterial adhesion in vitro, implant infection still developed in in vivo studies. Furthermore, the results also revealed that both NTs and NT-V showed good biocompatibility. Therefore, the NTs loaded with antibiotic might be potentially used for future orthopedic implants.

  2. Fabrication and characterization of gold nanoparticle-loaded TiO2 nanotube arrays for medical implants.

    PubMed

    Bai, Yu; Bai, Yulong; Wang, Cunyang; Gao, Jingjun; Ma, Wen

    2016-02-01

    Au nanoparticles (AuNPs) are successfully assembled on TiO2 nanotube (TN) arrays through electrochemical deposition technology to improve the surface characteristics of TN arrays as an implant material. The loading amount of AuNPs can be controlled by adjusting the deposition time of electrochemical deposition. The effect of the amount of the loaded AuNPs on surface roughness and surface energy is systematically investigated on the basis of various characterizations. Results show that the increase in the loading amount of AuNPs on the TN arrays can increase surface roughness and decrease surface energy. Potentiodynamic polarization tests indicate that AuNP-modified TNs possess a higher corrosion resistance than unmodified TNs. Corrosion resistance increases as the amount of the loaded AuNP increases. In vitro cell culture tests are performed on the basis of cell morphology observations and MTT assays. Osteoblast cell adhesion and proliferation ability on the AuNP-modified TN surface are greater than those on the unmodified TN surface. The sample fabricated at the deposition time of 90 s exhibits an optimum cell performance. This work can provide a new platform to develop the surface chemistry of TN arrays and to fabricate titanium-based implant materials to enhance bioactivity.

  3. Aperiodic TiO2 Nanotube Photonic Crystal: Full-Visible-Spectrum Solar Light Harvesting in Photovoltaic Devices

    PubMed Central

    Guo, Min; Xie, Keyu; Wang, Yu; Zhou, Limin; Huang, Haitao

    2014-01-01

    Bandgap engineering of a photonic crystal is highly desirable for photon management in photonic sensors and devices. Aperiodic photonic crystals (APCs) can provide unprecedented opportunities for much more versatile photon management, due to increased degrees of freedom in the design and the unique properties brought about by the aperiodic structures as compared to their periodic counterparts. However, many efforts still remain on conceptual approaches, practical achievements in APCs are rarely reported due to the difficulties in fabrication. Here, we report a simple but highly controllable current-pulse anodization process to design and fabricate TiO2 nanotube APCs. By coupling an APC into the photoanode of a dye-sensitized solar cell, we demonstrate the concept of using APC to achieve nearly full-visible-spectrum light harvesting, as evidenced by both experimental and simulated results. It is anticipated that this work will lead to more fruitful practical applications of APCs in high-efficiency photovoltaics, sensors and optoelectronic devices. PMID:25245854

  4. Optical modeling-assisted characterization of dye-sensitized solar cells using TiO2 nanotube arrays as photoanodes

    PubMed Central

    Kim, Il Ku; Wang, Lianzhou; Amal, Rose

    2014-01-01

    Summary Photovoltaic characteristics of dye-sensitized solar cells (DSSCs) using TiO2 nanotube (TNT) arrays as photoanodes were investigated. The TNT arrays were 3.3, 11.5, and 20.6 μm long with the pore diameters of 50, 78.6, and 98.7 nm, respectively. The longest TNT array of 20.6 μm in length showed enhanced photovoltaic performances of 3.87% with significantly increased photocurrent density of 8.26 mA·cm−2. This improvement is attributed to the increased amount of the adsorbed dyes and the improved electron transport property with an increase in TNT length. The initial charge generation rate was improved from 4 × 1021 s−1·cm−3 to 7 × 1021 s−1·cm−3 in DSSCs based on optical modelling analysis. The modelling analysis of optical processes inside TNT-based DSSCs using generalized transfer matrix method (GTMM) revealed that the amount of dye and TNT lengths were critical factors influencing the performance of DSSCs, which is consistent with the experimental results. PMID:24991527

  5. Photoinduced deposition of gold nanoparticles on TiO2-WO3 nanotube films as efficient photoanodes for solar water splitting

    NASA Astrophysics Data System (ADS)

    Momeni, Mohamad Mohsen; Ghayeb, Yousef

    2016-06-01

    Gold-modified TiO2-WO3 nanotubes with different amounts of gold were obtained by two methods; photoassisted deposition and one-step electrochemical anodizing method. The morphology, crystallinity and elemental composition were studied by FE-SEM, XRD and EDX. The photoelectrochemical performance was examined under Xe light illumination in 1 M NaOH electrolyte. Characterization of the as-prepared TiO2-WO3 samples indicated that sodium tungstate concentration in anodizing solution significantly influenced the morphology and photoelectrochemical activity of fabricated films. Also, photoelectrochemical characterizations show that the photocatalytic activity of Au/TiO2-WO3 nanotubes was improved as compared with that of bare TiO2-WO3 nanotubes. The experimental results showed that the photocatalytic activities of Au/TiO2-WO3 were significantly affected by the amount of Au nanoparticles. The amount of gold nanoparticles was effectively controlled by time of photoreduction of the chloroauric acid solution. These new photoanodes showed enhanced high photocurrent density with good stability and are a highly promising photoanodes for photocatalytic hydrogen production.

  6. Fabrication of 3D interconnected porous TiO2 nanotubes templated by poly(vinyl chloride-g-4-vinyl pyridine) for dye-sensitized solar cells.

    PubMed

    Koh, Joo Hwan; Koh, Jong Kwan; Seo, Jin Ah; Shin, Jong-Shik; Kim, Jong Hak

    2011-09-07

    Porous TiO(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 µm long ZnO nanorod array was grown from the fluorine-doped tin oxide (FTO) glass via a liquid phase deposition method. The TiO(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(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(w)) and 0.74% for high M(w) polymer electrolytes.

  7. Self-Cleaning Glass of Photocatalytic Anatase TiO2@Carbon Nanotubes Thin Film by Polymer-Assisted Approach

    NASA Astrophysics Data System (ADS)

    Yi, Qinghua; Wang, Hao; Cong, Shan; Cao, Yingjie; Wang, Yun; Sun, Yinghui; Lou, Yanhui; Zhao, Jie; Wu, Jiang; Zou, Guifu

    2016-10-01

    Due to the good photocatalytic activity, the TiO2@CNTs thin film is highly desirable to apply to the self-cleaning glass for green intelligent building. Here, the TiO2@CNTs thin film has been successfully achieved by polymer-assisted approach of an aqueous chemical solution method. The polymer, polyethylenimine, aims to combine the Ti4+ with CNTs for film formation of TiO2@CNTs. The resultant thin film was uniform, highly transparent, and super-hydrophilic. Owing to fast electron transport and effectively hindering electron-hole recombination, the TiO2@CNTs thin film has nearly twofold photocatalytic performance than pure TiO2. The TiO2@CNTs thin films show a good application for self-cleaning glasses.

  8. Self-Cleaning Glass of Photocatalytic Anatase TiO2@Carbon Nanotubes Thin Film by Polymer-Assisted Approach.

    PubMed

    Yi, Qinghua; Wang, Hao; Cong, Shan; Cao, Yingjie; Wang, Yun; Sun, Yinghui; Lou, Yanhui; Zhao, Jie; Wu, Jiang; Zou, Guifu

    2016-12-01

    Due to the good photocatalytic activity, the TiO2@CNTs thin film is highly desirable to apply to the self-cleaning glass for green intelligent building. Here, the TiO2@CNTs thin film has been successfully achieved by polymer-assisted approach of an aqueous chemical solution method. The polymer, polyethylenimine, aims to combine the Ti(4+) with CNTs for film formation of TiO2@CNTs. The resultant thin film was uniform, highly transparent, and super-hydrophilic. Owing to fast electron transport and effectively hindering electron-hole recombination, the TiO2@CNTs thin film has nearly twofold photocatalytic performance than pure TiO2. The TiO2@CNTs thin films show a good application for self-cleaning glasses.

  9. Interface Architecture Determined Electrocatalytic Activity of Pt on Vertically Oriented TiO2 Nanotubes

    SciTech Connect

    R Rettew; N Allam; F Alamgir

    2011-12-31

    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{sub 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{sub 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{sub 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.

  10. Surface wettability of TiO2 nanotube arrays prepared by electrochemical anodization

    NASA Astrophysics Data System (ADS)

    Liu, Guohua; Du, Kang; Wang, Kaiying

    2016-12-01

    This work reports structural engineering and wettability of titania nanotube arrays (TNTs). The nanotube diameter and thickness of TNT layer increase with increasing of applied voltage from 20 to 40, 60 and 80 V, and the diameter has no relevance to extending anodic duration. The fabricated TNTs are 30-190 nm inner diameter and 5-40 mm height. 10 mL water droplets are applied to define wettability of the TNTs by measuring contact angles. Hydrophilicity is enhanced with increasing diameter of TNTs as well as over-etching occurring on the surface. Large diameter tubes and capillary force provide more space and power for liquid to penetration. The contact angle reduces from 35° to 2° with the tube diameter increasing from 30 to 190 nm. Bare Ti foil is inherently hydrophobic with approximately 90° contact angle. The as-prepared TNTs are hydrophilic with contact angle of 24°, and annealing further improves this property to a contact angle of 13°. The bottom of TNTs shows superhydrophilic due to hydroxide compounds existed on the surface. The metal substrate with tube footprint left presents hydrophobic with contact angle of 68°, which is lower than the bare one. It is believed that wettability on the surface of TNTs is dependent on their morphology and chemical composition.

  11. Ag Nanoparticles Located on Three-Dimensional Pine Tree-Like Hierarchical TiO2 Nanotube Array Films as High-Efficiency Plasmonic Photocatalysts

    NASA Astrophysics Data System (ADS)

    Xu, Jinxia; Wang, Zhenhuan; Li, Wenqing; Zhang, Xingang; He, Dong; Xiao, Xiangheng

    2017-01-01

    High specific surface area three-dimensional pine tree-like hierarchical TiO2 nanotube array films loaded with Ag nanoparticles were successfully prepared by one-step hydrothermal reaction combining with simple and feasible magnetron sputtering. The composite Ag/TiO2-branched nanotube arrays show outstanding photocatalytic property, which is attributed to the boost of plasmonic enhancement carrier generation and separation, higher specific surface area, higher organic pollutant absorption, faster charge transport, and superior light-harvesting efficiency for efficient charge collection. The work provides a cost-effective and flexible pathway to develop high-performance photocatalyst or optoelectronic devices.

  12. TiO2 nanotube composite layers as delivery system for ZnO and Ag nanoparticles - an unexpected overdose effect decreasing their antibacterial efficacy.

    PubMed

    Roguska, A; Belcarz, A; Pisarek, M; Ginalska, G; Lewandowska, M

    2015-06-01

    Enhancement of biocompatibility and antibacterial properties of implant materials is potentially beneficial for their practical value. Therefore, the use of metallic and metallic oxide nanoparticles as antimicrobial coatings components which induce minimized antibacterial resistance receives currently particular attention. In this work, TiO2 nanotubes layers loaded with ZnO and Ag nanoparticles were designed for biomedical coatings and delivery systems and evaluated for antimicrobial activity. TiO2 nanotubes themselves exhibited considerable and diameter-dependent antibacterial activity against planktonic Staphylococcus epidermidis cells but favored bacterial adhesion. Loading of nanotubes with moderate amount of ZnO nanoparticles significantly diminished S. epidermidis cell adhesion and viability just after 1.5h contact with modified surfaces. However, an increase of loaded ZnO amount unexpectedly altered the structure of nanoparticle-nanolayer, caused partial closure of nanotube interior and significantly reduced ZnO solubility and antibacterial efficacy. Co-deposition of Ag nanoparticles enhanced the antibacterial properties of synthesized coatings. However, the increase of ZnO quantity on Ag nanoparticles co-deposited surfaces favored the adhesion of bacterial cells. Thus, ZnO/Ag/TiO2 nanotube composite layers may be promising delivery systems for combating post-operative infections in hard tissue replacement procedures. However, the amount of loaded antibacterial agents must be carefully balanced to avoid the overdose and reduced efficacy.

  13. TiO2 nanotube platforms for smart drug delivery: a review

    PubMed Central

    Wang, Qun; Huang, Jian-Ying; Li, Hua-Qiong; Chen, Zhong; Zhao, Allan Zi-Jian; Wang, Yi; Zhang, Ke-Qin; Sun, Hong-Tao; Al-Deyab, Salem S; Lai, Yue-Kun

    2016-01-01

    Titania nanotube (TNT) arrays are recognized as promising materials for localized drug delivery implants because of their excellent properties and facile preparation process. This review highlights the concept of localized drug delivery systems based on TNTs, considering their outstanding biocompatibility in a series of ex vivo and in vivo studies. Considering the safety of TNT implants in the host body, studies of the biocompatibility present significant importance for the clinical application of TNT implants. Toward smart TNT platforms for sustainable drug delivery, several advanced approaches were presented in this review, including controlled release triggered by temperature, light, radiofrequency magnetism, and ultrasonic stimulation. Moreover, TNT implants used in medical therapy have been demonstrated by various examples including dentistry, orthopedic implants, cardiovascular stents, and so on. Finally, a future perspective of TNTs for clinical applications is provided. PMID:27703349

  14. TiO2 nanotube platforms for smart drug delivery: a review.

    PubMed

    Wang, Qun; Huang, Jian-Ying; Li, Hua-Qiong; Chen, Zhong; Zhao, Allan Zi-Jian; Wang, Yi; Zhang, Ke-Qin; Sun, Hong-Tao; Al-Deyab, Salem S; Lai, Yue-Kun

    Titania nanotube (TNT) arrays are recognized as promising materials for localized drug delivery implants because of their excellent properties and facile preparation process. This review highlights the concept of localized drug delivery systems based on TNTs, considering their outstanding biocompatibility in a series of ex vivo and in vivo studies. Considering the safety of TNT implants in the host body, studies of the biocompatibility present significant importance for the clinical application of TNT implants. Toward smart TNT platforms for sustainable drug delivery, several advanced approaches were presented in this review, including controlled release triggered by temperature, light, radiofrequency magnetism, and ultrasonic stimulation. Moreover, TNT implants used in medical therapy have been demonstrated by various examples including dentistry, orthopedic implants, cardiovascular stents, and so on. Finally, a future perspective of TNTs for clinical applications is provided.

  15. Integrin-mediated osteoblastic adhesion on a porous manganese-incorporated TiO2 coating prepared by plasma electrolytic oxidation

    PubMed Central

    ZHANG, ZHENXIANG; GU, BEIBEI; ZHU, WEI; ZHU, LIXIAN

    2013-01-01

    This study was conducted to evaluate the bioactivity of manganese-incorporated TiO2 (Mn-TiO2) coating prepared on titanium (Ti) plate by plasma electrolytic oxidation (PEO) technique in Ca-, P- and Mn-containing electrolytes. The surface topography, phase and element compositions of the coatings were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometry (EDS), respectively. The adhesion of osteoblast-like MG63 cells onto Ti, TiO2 and Mn-TiO2 surfaces was evaluated, and the signal transduction pathway involved was confirmed by the sequential expression of the genes for integrins β1, β3, α1 and α3, focal adhesion kinase (FAK), and the extracellular regulated kinases (ERKs), including ERK1 and ERK2. The results obtained indicated that Mn was successfully incorporated into the porous nanostructured TiO2 coating, and did not alter the surface topography or the phase composition of the coating. The adhesion of the MG63 cells onto the Mn-incorporated TiO2 coating was significantly enhanced compared with that on the Mn-free TiO2 coating and the pure Ti plates. In addition, the enhanced cell adhesion on the Mn-TiO2 coatings may have been mediated by the binding of the integrin subunits, β1 and α1, and the subsequent signal transduction pathway, involving FAK and ERK2. The study indicated that the novel Mn-TiO2 coating has potential for orthopedic implant applications, and that further investigations are required. PMID:24137252

  16. Integrin-mediated osteoblastic adhesion on a porous manganese-incorporated TiO2 coating prepared by plasma electrolytic oxidation.

    PubMed

    Zhang, Zhenxiang; Gu, Beibei; Zhu, Wei; Zhu, Lixian

    2013-09-01

    This study was conducted to evaluate the bioactivity of manganese-incorporated TiO2 (Mn-TiO2) coating prepared on titanium (Ti) plate by plasma electrolytic oxidation (PEO) technique in Ca-, P- and Mn-containing electrolytes. The surface topography, phase and element compositions of the coatings were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometry (EDS), respectively. The adhesion of osteoblast-like MG63 cells onto Ti, TiO2 and Mn-TiO2 surfaces was evaluated, and the signal transduction pathway involved was confirmed by the sequential expression of the genes for integrins β1, β3, α1 and α3, focal adhesion kinase (FAK), and the extracellular regulated kinases (ERKs), including ERK1 and ERK2. The results obtained indicated that Mn was successfully incorporated into the porous nanostructured TiO2 coating, and did not alter the surface topography or the phase composition of the coating. The adhesion of the MG63 cells onto the Mn-incorporated TiO2 coating was significantly enhanced compared with that on the Mn-free TiO2 coating and the pure Ti plates. In addition, the enhanced cell adhesion on the Mn-TiO2 coatings may have been mediated by the binding of the integrin subunits, β1 and α1, and the subsequent signal transduction pathway, involving FAK and ERK2. The study indicated that the novel Mn-TiO2 coating has potential for orthopedic implant applications, and that further investigations are required.

  17. Pseudocapacitive Lithium-Ion Storage in Oriented Anatase TiO2 Nanotube Arrays

    SciTech Connect

    Zhu, K.; Wang, Q.; Kim, J. H.; Pesaran, A. A.; Frank, A. J.

    2012-06-07

    We report on the synthesis and electrochemical properties of oriented anatase TiO{sub 2} nanotube (NT) arrays as electrodes for Li-ion batteries. The TiO{sub 2} NT electrodes displayed both pseudocapacitive Li{sup +} storage associated with the NT surface and the Li{sup +} storage within the bulk material. The relative contribution of the pseudocapacitive and bulk storages depends strongly on the scan rate. While the charges are stored primarily in the bulk at low scan rates (<< 1 mV/s), the surface storage dominates the total storage capacity at higher scan rates (>1 mV/s). The storage capacity of the NT electrodes as a function of charge/discharge rates showed no dependence on the NT film thickness, suggesting that the Li{sup +} insertion/extraction processes occur homogeneously across the entire length of NT arrays. These results indicated that the electron conduction along the NT walls and the ion conduction within the electrolyte do not cause significant hindering of the charge/discharge kinetics for NT electrode architectures. As a result of the surface pseudocapacitive storage, the reversible Li{sup +} storage capacities for TiO{sub 2} NT electrodes were higher than the theoretical storage capacity for bulk anatase TiO{sub 2} materials.

  18. Theoretical and photo-electrochemical studies of surface plasmon induced visible light absorption of Ag loaded TiO2 nanotubes for water splitting

    NASA Astrophysics Data System (ADS)

    Gross, P. A.; Javahiraly, N.; Geraldini Sabat, N.; Cottineau, T.; Savinova, E. R.; Keller, V.

    2016-10-01

    Vertically aligned TiO2 nanotubes (TiO2-NTs), obtained by anodization in organic electrolyte, are decorated with 15 nm Ag nanoparticles prepared by a micro-wave assisted polyol synthesis. The Ag/TiO2 system is characterized by electronic microscopies in order to build a Finite Differential Time Domain (FDTD) model to simulate the interaction of light with the system. By combining UV-visible spectroscopy and FDTD simulations, the observed red shift in the surface plasmon resonance wavelength of the Ag nanoparticles, deposited on TiO2, is explained. The Ag/TiO2-NT system is used as photoanode in a photoelectrochemical water splitting setup and shows an increasing Incident Photon to Current Conversion Efficiency (IPCE) in the visible light domain with an increasing amount of deposited Ag. The spectral position of this activity enhancement coincides with the one expected from the FDTD calculations for the surface plasmon resonance of the Ag nanoparticles deposited on TiO2.

  19. Self-organized TiO2 nanotube arrays: synthesis by anodization in an ionic liquid and assessment of photocatalytic properties.

    PubMed

    Wender, Heberton; Feil, Adriano F; Diaz, Leonardo B; Ribeiro, Camila S; Machado, Guilherme J; Migowski, Pedro; Weibel, Daniel E; Dupont, Jairton; Teixeira, Sérgio R

    2011-04-01

    Self-organized TiO(2) nanotube (NT) arrays were produced by anodization in ethylene glycol (EG) electrolytes containing 1-n-butyl-3-methyl-imidazolium tetrafluoroborate (BMI.BF(4)) ionic liquid and water. The morphology of the as-formed NTs was considerably affected by changing the anodization time, voltage, and water and ionic liquid electrolyte concentrations. In general, a nanoporous layer was formed on the top surface of the TiO(2) NTs, except for anodization at 100 V with 1 vol % of BMI.BF(4), where the NT's mouth was revealed. The length and bottom diameter of the NTs as well as the pore diameter of the top layer showed a linear relationship with increased anodization voltage. These TiO(2) NTs were tested as photocatalysts for methyl orange photodegradation and hydrogen evolution from water/methanol solutions by UV light irradiation. The results show that the TiO(2) NTs obtained by anodization in EG/H(2)O/BMI.BF(4) electrolytes are active and efficient for both applications.

  20. Co3O4-modified TiO2 nanotube arrays via atomic layer deposition for improved visible-light photoelectrochemical performance.

    PubMed

    Huang, Bin; Yang, Wenjuan; Wen, Yanwei; Shan, Bin; Chen, Rong

    2015-01-14

    Composite Co3O4/TiO2 nanotube arrays (NTs) were fabricated via atomic layer deposition (ALD) of Co3O4 thin film onto well-aligned anodized TiO2 NTs. The microscopic morphology, composition, and interfacial plane of the composite structure were characterized by scanning electron microscopy, energy dispersion mapping, X-ray photoelectron spectra, and high-resolution transmission electron microscopy. It was shown that the ultrathin Co3O4 film uniformly coat onto the inner wall of the high aspect ratio (>100:1) TiO2 NTs with film thickness precisely controlled by the number of ALD deposition cycles. The composite structure with ∼4 nm Co3O4 coating revealed optimal photoelectrochemical (PEC) performance in the visible-light range (λ > 420 nm). The photocurrent density reaches as high as 90.4 μA/cm(2), which is ∼14 times that of the pristine TiO2 NTs and 3 times that of the impregnation method. The enhanced PEC performance could be attributed to the finely controlled Co3O4 coating layer that enhances the visible-light absorption, maintains large specific surface area to the electrolyte interface, and facilitates the charge transfer.

  1. Very low amount of TiO2 on N-doped carbon nanotubes significantly improves oxygen reduction activity and stability of supported Pt nanoparticles.

    PubMed

    Zhao, Anqi; Masa, Justus; Xia, Wei

    2015-04-28

    Electrochemical corrosion is a major problem for carbon materials used in electrocatalysis. Highly dispersed TiO2 was deposited on O-functionalized and N-doped carbon nanotubes by chemical vapour deposition to tackle the carbon corrosion problem. Very low Ti loadings of about 1 wt% were applied to minimize the negative influence of TiO2 as a semiconductor on the high conductivity of carbon materials. Both N doping and TiO2 coating facilitate strong metal-support interactions and favour the formation of small Pt particles. N doping improved the intrinsic catalytic activity of the carbon support and enhanced the conductivity due to the removal of surface oxygen groups, while the negative effect of TiO2 on conductivity is counterbalanced by its promoting effect on metal-support interactions leading to enhanced overall catalytic performance. Pt/TiO2/NCNTs showed the highest ORR activity, and significantly outperformed Pt/NCNTs in electrochemical stability tests.

  2. Low temperature transfer of well-tailored TiO2 nanotube array membrane for efficient plastic dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Fu, Nianqing; Li, Xiaoyan; Liu, Yan; Liu, Yanchun; Guo, Min; Li, Wenfang; Huang, Haitao

    2017-03-01

    Transferring semiconductor film onto plastic substrate for efficient flexible photovoltaic devices with good mechanical stability against shape wrench is always a big challenge. In this work, well-designed TiO2 nanotube array (TNTA) membrane is achieved by a combination of hot-water-soaking and TiCl4 post-treatment for efficient plastic DSSCs. In this engineered TiO2 architecture, the TiO2 particle decorated and nanowire capped TNTA hybrid structure provides not only enormous dye-loading amount and excellent light scattering/trapping effects for superior light harvesting efficiency, but also fast charge transport along the 1D aligned TNTA scaffold. More importantly, the thin and mesoporous TiO2 layer deposited on the bottom surface of TNTA makes it is possible to form mechanical interlocking between TNTA membrane and the adhesive layer to insure the excellent mechanical stability and efficient electron transfer from the TNTA membrane to the substrate. The plastic DSSCs based on the well-tailored TNTA membranes yield an exciting efficiency of 6.25% and at the same time maintain 90% of its initial efficiency after hundreds of bending cycles.

  3. Gold nanocluster sensitized TiO2 nanotube arrays for visible-light driven photoelectrocatalytic removal of antibiotic tetracycline

    NASA Astrophysics Data System (ADS)

    Liu, Yanbiao; Yao, Qiaofeng; Wu, Xuejun; Chen, Tiankai; Ma, Ying; Ong, Choon Nam; Xie, Jianping

    2016-05-01

    It is of technical interest to develop low-cost, high-quality and scalable photosensitizers that could efficiently harvest visible light. Here we design an efficient photoelectrocatalyst by integrating a recently developed gold nanocluster (AuNC, as a photosensitizer) into two types of highly ordered TiO2 nanotube arrays (TNAs, as substrates to host the photosensitizers). The TNA electrodes used in this study are a short TNA (~0.5 µm in length, synthesized by the anodic oxidation in an aqueous hydrofluoric (HF) acid solution) and a long TNA (~4.5 µm in length, synthesized by the anodic oxidation in a fluorinated ethylene glycol (EG) solution). A number of characterization techniques (e.g., FESEM, XRD and XPS) were applied to study the as-synthesized nanocomposites. In particular, diffuse reflectance spectroscopy and photochemical measurements suggest that the AuNC-coated TNA electrodes have successfully extended visible light absorption and improved their photochemical performance. Compared with the blank TNAs, the as-designed nanocomposites exhibit an evidently enhanced photoelectrocatalytic performance towards tetracycline (an emerging antibiotic contaminant in aquatic environment) decomposition, where the removal efficiency increases from 65% to 81% for AuNC/long-TNA and from 46% to 73% for AuNC/short-TNA electrodes, respectively. The improved performance is largely attributed to the photo-electro-chemical synergetic effect. The photochemical performance of the as-designed nanocomposites could be further improved by fine tuning the size, composition, and surface of the AuNC-based photosensitizers.It is of technical interest to develop low-cost, high-quality and scalable photosensitizers that could efficiently harvest visible light. Here we design an efficient photoelectrocatalyst by integrating a recently developed gold nanocluster (AuNC, as a photosensitizer) into two types of highly ordered TiO2 nanotube arrays (TNAs, as substrates to host the

  4. A simple low pressure method for the synthesis of TiO2 nanotubes and nanofibers and their application in DSSCs

    NASA Astrophysics Data System (ADS)

    Karimipour, Masoud; Mashhoun, Sara; Mollaei, Mohsen; Molaei, Mehdi; Taghavinia, Nima

    2015-07-01

    TiO2 nanotubes were synthesized using a modified autoclave-free thermal method from as-prepared initial powders. The size of initial powders (IP) was found to be critical in determining the morphology and crystal structure of the final product. Oleylamine (OA) was used as the polymer agent in the preparation of initial powders with different mol ratios of OA/Ti: 1, 5, and 10. X-ray diffraction analysis depicted that the increase of mole ratio up to 10 resulted in smaller nanoparticles with the sizes of about 8 nm. It was also deliberated that low temperature thermally treated IP showed the characteristic diffraction pattern of titanate phase of nanotubes. Scanning electron microscope images showed nanorods, short nanotubes, and single-phase long and uniform nanofibers produced from initial powders. SEM cross-section of the anode cell of TiO2 nanofibers demonstrated the presence of uniformly closed net long fibers in the cell. Open circuit voltage measurements of the nanofiber cell demonstrated a several hundreds of seconds in the electron transport decay, which was significantly higher than that of the nanoparticles. IMPS/IMVS measurements of the nanofibers and nanotube solar cells showed electron transport enhancement and long life time compared to their nanoparticle counterparts. [Figure not available: see fulltext.

  5. TiO2 nanotubes wrapped with reduced graphene oxide as a high-performance anode material for lithium-ion batteries

    PubMed Central

    Zheng, Peng; Liu, Ting; Su, Ying; Zhang, Lifeng; Guo, Shouwu

    2016-01-01

    Through electrostatic interaction and high-temperature reduction methods, rGO was closely coated onto the surface of TiO2 nanotubes. Even at a high temperature of 700 °C, the nanotube morphology of TiO2 (anatase) was preserved because of the assistance of rGO, which provides a framework that prevents the tubes from breaking into particles and undergoing a phase transformation. The rGO/TiO2 nanotubes deliver a high capacity (263 mAh g−1 at the end of 100 cycles at 0.1 A g−1), excellent rate performance (151 mAh g−1 at 2 A g−1 and 102 mAh g−1 at 5 A g−1), and good cycle stability (206 mAh g−1 after 500 cycles at 0.5 A g−1). These characteristics arise from the GO/TiO2 nanotubes’ advanced structure. First, the closely coated rGO and Ti3+ in the tubes give rise to a high electro-conductivity of the nanotubes. Additionally, the Li+ ions can rapidly transfer into the electrode via the nanotubes’ empty inner diameter and short tube wall. PMID:27808271

  6. Characterization of the structure, thermal stability and wettability of the TiO2 nanotubes growth on the Ti-7.5Mo alloy surface

    NASA Astrophysics Data System (ADS)

    Chaves, J. M.; Escada, A. L. A.; Rodrigues, A. D.; Alves Claro, A. P. R.

    2016-05-01

    In this study, the Ti-7.5Mo experimental alloy for biomedical applications was processed showing orthorhombic (α″) martensite phase and low elastic modulus (54 GPa). The surface treatment permitted the growth of ordered TiO2 nanotubes via anodization process. The heat treatment during in situ Raman measurement revealed that the TiO2 nanotubes were transformed of the amorphous state for crystalline (anatase phase) around 400 °C. Annealing of the nanotubes was evaluated by XRD, SEM and Raman spectroscopy. Results showed a high stability of the nanostructure, since only for temperatures above of 500 °C, at which the phase rutile appears, the nanostructure tends to vanish. It was observed in Raman analysis an increasing of the average size of the crystallite of the anatase phase with annealing temperature ranging from 6.5 nm up to 13 nm, besides of the precipitation of the layer rutile in the interface nanotubes-substrate. It is believed that the contact between anatase crystallites or layer rutile of the interface lead to growth of the rutile phase, causing coalescence and subsequent collapse of the tubular nanostructure. The wettability, as well as, surface energy was dependent of the crystalline structure and morphology, becoming more hydrophilic in the anatase phase when as compared with amorphous and rutile phase. The typical features of the surface together excellent bulk properties (low elastic modulus) of the Ti-7.5Mo alloy can provide a guideline for future biomedical applications.

  7. A high-throughput reaction system to measure the gas-phase photocatalytic oxidation activity of TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Grasser, Jordan A.; Muggli, Darrin S.

    2009-07-01

    A sixteen-channel, high-throughput system was designed and built to test the activity of catalysts for gas-phase photocatalytic oxidation of methanol. The system utilizes granular catalyst films to model relevant applications and allow for rapid processing. It is capable of 48 catalyst tests per day using the procedure described herein. Several experiments were performed to minimize both the within-node and between-node variances of the system. Utilizing the high-throughput system, the significance of preparation methods on the photocatalytic activity of TiO2 nanotubes was investigated. A one-half fractional factorial experiment identified the factors that significantly impact catalyst activity as the following: precursor type (Degussa P-25, or nanotubes), platinum loading, the interaction between precursor and dope time, and the interaction between the precursor and calcination temperature. Based on experimental results, catalyst activity is optimized by doping TiO2 nanotubes directly (rather than doping P-25 prior to nanotube formation), a low platinum loading (0.01 wt %), and using a dope time of 30 min followed by calcination at 773 K. The optimum catalyst preparation conditions produced a catalyst that was three times more active than the starting P-25 material.

  8. TiO2 nanotubes wrapped with reduced graphene oxide as a high-performance anode material for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zheng, Peng; Liu, Ting; Su, Ying; Zhang, Lifeng; Guo, Shouwu

    2016-11-01

    Through electrostatic interaction and high-temperature reduction methods, rGO was closely coated onto the surface of TiO2 nanotubes. Even at a high temperature of 700 °C, the nanotube morphology of TiO2 (anatase) was preserved because of the assistance of rGO, which provides a framework that prevents the tubes from breaking into particles and undergoing a phase transformation. The rGO/TiO2 nanotubes deliver a high capacity (263 mAh g-1 at the end of 100 cycles at 0.1 A g-1), excellent rate performance (151 mAh g-1 at 2 A g-1 and 102 mAh g-1 at 5 A g-1), and good cycle stability (206 mAh g-1 after 500 cycles at 0.5 A g-1). These characteristics arise from the GO/TiO2 nanotubes’ advanced structure. First, the closely coated rGO and Ti3+ in the tubes give rise to a high electro-conductivity of the nanotubes. Additionally, the Li+ ions can rapidly transfer into the electrode via the nanotubes’ empty inner diameter and short tube wall.

  9. Self-Organized Amorphous TiO2 Nanotube Arrays on Porous Ti Foam for Rechargeable Lithium and Sodium Ion Batteries

    SciTech Connect

    Bi, Zhonghe; Paranthaman, Mariappan Parans; Menchhofer, Paul A; Dehoff, Ryan R; Bridges, Craig A; Chi, Miaofang; Guo, Bingkun; Sun, Xiao-Guang; Dai, Sheng

    2013-01-01

    Self-organized amorphous TiO2 nanotube arrays (NTAs) were successfully fabricated on both Ti foil and porous Ti foam through electrochemical anodization techniques. The starting Ti foams were fabricated using ARCAM s Electron Beam Melting (EBM) technology. The TiO2 NTAs on Ti foam were used as anodes in lithium ion batteries; they exhibited high capacities of 103 Ahcm-2 at 10 Acm-2 and 83 Ahcm-2 at 500 Acm-2, which are two to three times higher than those achieved on the standard Ti foil, which is around 40 Ahcm-2 at 10 Acm-2 and 24 Ahcm-2 at 500 Acm-2, respectively. This improvement is mainly attributed to higher surface area of the Ti foam and higher porosity of the nanotube arrays layer grown on the Ti foam. In addition, a Na-ion half-cell composed of these NTAs anodes and Na metal showed a self-improving specific capacity upon cycling at 10 Acm-2. These results indicate that TiO2 NTAs grown on Ti porous foam are promising electrodes for Li-ion or Na-ion rechargeable batteries.

  10. Layer-by-layer assembly of TiO2 nanowire/carbon nanotube films and characterization of their photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Darányi, Mária; Csesznok, Tamás; Kukovecz, Ákos; Kónya, Zoltán; Kiricsi, Imre; Ajayan, Pulickel M.; Vajtai, Robert

    2011-05-01

    We report on the layer-by-layer (LbL) formation of TiO2-MWNT-TiO2 coatings on quartz with either trititanate derived TiO2 nanowires or Degussa P25 as the photocatalytically active material. The optimized deposition sequence is discussed in detail and the morphology of the prepared coatings is analyzed by SEM and XRD. The heterogeneous photocatalytic performance of the coatings was tested in the methyl orange oxidation reaction. The apparent first order rate constant fell in the 0.01-0.20 h - 1 range over a 2.5 × 2.5 cm2 film depending on the type and the thickness of the titanate coating. Building a multiwall carbon nanotube layer into the middle of the layer improved the photocatalytic activity for each material for all of the studied thicknesses. P25 based films performed 2-5 times better than TiO2 nanowire films; however, the pores in the P25 based films were largely blocked because the isotropic P25 nanoparticles form closely packed layers by themselves and even more so with the comparably sized multiwall carbon nanotubes. Therefore, films derived from titanate nanowires appear to be more suitable for use as multifunctional, photocatalytically active filtration media.

  11. Layer-by-layer assembly of TiO2 nanowire/carbon nanotube films and characterization of their photocatalytic activity.

    PubMed

    Darányi, Mária; Csesznok, Tamás; Kukovecz, Akos; Kónya, Zoltán; Kiricsi, Imre; Ajayan, Pulickel M; Vajtai, Robert

    2011-05-13

    We report on the layer-by-layer (LbL) formation of TiO(2)-MWNT-TiO(2) coatings on quartz with either trititanate derived TiO(2) nanowires or Degussa P25 as the photocatalytically active material. The optimized deposition sequence is discussed in detail and the morphology of the prepared coatings is analyzed by SEM and XRD. The heterogeneous photocatalytic performance of the coatings was tested in the methyl orange oxidation reaction. The apparent first order rate constant fell in the 0.01-0.20 h(-1) range over a 2.5 × 2.5 cm(2) film depending on the type and the thickness of the titanate coating. Building a multiwall carbon nanotube layer into the middle of the layer improved the photocatalytic activity for each material for all of the studied thicknesses. P25 based films performed 2-5 times better than TiO(2) nanowire films; however, the pores in the P25 based films were largely blocked because the isotropic P25 nanoparticles form closely packed layers by themselves and even more so with the comparably sized multiwall carbon nanotubes. Therefore, films derived from titanate nanowires appear to be more suitable for use as multifunctional, photocatalytically active filtration media.

  12. Fabrication of transparent TiO2 nanotube-based photoanodes for CdS/CdTe quantum co-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Gualdrón-Reyes, A. F.; Cárdenas-Arenas, A.; Martínez, C. A.; Kouznetsov, V. V.; Meléndez, A. M.

    2017-01-01

    In order to fabricate a solar cell, ordered TiO2 nanotube (TNT) arrays were prepared by double anodization. TNT arrays with variable lengths were obtained by changing the duration of the anodizing process of up to 3h. TNT membranes were transferred to indium tin oxide substrates and attached with a B-TiO2 sol. TNT photoanode with the best photoelectrochemical performance was sensitized with CdS by SILAR method. On other hand, CdTe quantum dots prepared via colloidal synthesis were deposited on TNT photoanodes for 2h, 4h and 6h. In addition, TNT/CdS was loaded with CdTe quantum dots for 4 h. Morphology and chemical modification of TiO2 were characterized by FESEM and XPS, while their photoelectrochemical performance was measured by open-circuit photopotential and photovoltammetry under visible light. TiO2 nanotubes grown during 2.5h showed the highest photocurrent due to presence of Ti3+ donor states by N and F co-doping, increasing the number of photogenerated electrons transported to back collector. TNT/CdS/CdTe photoanode reach the highest conversion efficiency under AM 1.5G simulated solar illumination.

  13. Influence of the Ti microstructure on anodic self-organized TiO2 nanotube layers produced in ethylene glycol electrolytes

    NASA Astrophysics Data System (ADS)

    Macak, J. M.; Jarosova, M.; Jäger, A.; Sopha, H.; Klementová, M.

    2016-05-01

    The relationship between the microstructure of Ti substrates and the anodic growth of self-organized TiO2 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 NH4F 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 TiO2 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 nanotubes grown on various grains was investigated showing non-negligible differences in the diameter for different grain orientations and substrates.

  14. The controlled release of simvastatin from TiO2 nanotubes to promote osteoblast differentiation and inhibit osteoclast resorption

    NASA Astrophysics Data System (ADS)

    Lai, Min; Jin, Ziyang; Yang, Xinyi; Wang, Huaying; Xu, Kui

    2017-02-01

    The aim of this study was to fabricate a novel drug-releasing bioactive platform that has excellent potential for improving osteoblast differentiation and inhibiting osteoclast resorption. TiO2 nanotubes (TNTs) with an outer diameter of around 70 nm were prepared by an anodization method. TNTs were filled with simvastatin (SV) and then coated using chitosan/gelatin multilayers (TNT-SV-LBL). The successful fabrication of TNT-SV-LBL substrates was confirmed by field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle measurement, respectively. The in vitro release behavior of simvastatin from TNT-SV-LBL substrates showed a sustained release as compared to the uncoated group. Osteoblasts adhering to TNT-SV-LBL substrates attached well and displayed significantly higher (p < 0.01) cell viability compared with the other substrates. More importantly, osteoblasts grown on TNT-SV-LBL substrates displayed a statistically significant (p < 0.01 or p < 0.05) increase in protein production levels of alkaline phosphatase (ALP), osteocalcin (OC) and mRNA expression of runt related transcription factor 2 (Runx2), ALP, collagen type I (Col I), osteopontin (OPN), OC and osteoprotegerin (OPG) compared to the other groups after 4, 7 and 14 days of culture, respectively. Additionally, multinuclear osteoclastic differentiation of RAW264.7 cells grown on TNT-SV-LBL substrates was inhibited as confirmed by tartrate-resistant acid phosphatase (TRAP) analysis. These results demonstrated that bio-functionalized substrates with SV and chitosan/gelatin multilayers have great potential for improving osteoblast differentiation, as well as inhibiting osteoclast formation. Therefore, these advanced surface and chemical capabilities make this substrate well suited for the development of a drug-releasing Ti implant for bone regeneration.

  15. An Investigation on Effects of TiO2 Nano-Particles Incorporated in Electroless NiP Coatings' Properties

    NASA Astrophysics Data System (ADS)

    Allahkaram, S. R.; Salmi, S.; Tohidlou, E.

    Electroless composite coatings have been vastly used in various industries during last decades due to their good properties, such as corrosion and wear resistance, hardness and uniform thickness. In this paper, co-deposition of TiO2 nano-particles with Nickel-Phosphorus electroless coatings on API-5L-X65 steel substrates was investigated. Surface morphology and composition of coatings were studied via SEM and EDX, respectively. XRD analyses showed that these coatings had amorphous structure with TiO2 crystalline particles. TiO2 nano-particles increased microhardness of coatings. Corrosion resistance of these coatings was tested using linear polarization in 0.5M sulfuric acid electrolyte. Results showed that NiP-TiO2 electroless composite coatings increased corrosion resistance of substrates.

  16. High-Performance Stable Field Emission with Ultralow Turn on Voltage from rGO Conformal Coated TiO2 Nanotubes 3D Arrays

    PubMed Central

    Agrawal, Yogyata; Kedawat, Garima; Kumar, Pawan; Dwivedi, Jaya; Singh, V. N.; Gupta, R. K.; Gupta, Bipin Kumar

    2015-01-01

    A facile method to produce conformal coated reduced graphene oxide (rGO) on vertically aligned titanium oxide (TiO2) nanotubes three dimensional (3D) arrays (NTAs) is demonstrated for enhanced field emission display applications. These engineered nano arrays exhibit efficient electron field emission properties such as high field emission current density (80 mA/cm2), low turn-on field (1.0 V/μm) and field enhancement factor (6000) with high emission current stability. Moreover, these enhancements observed in nano arrays attribute to the contribution of low work function with non-rectifying barriers, which allow an easy injection of electrons from the conduction band of TiO2 into the Fermi level of reduced graphene oxide under external electric field. The obtained results are extremely advantageous for its potential application in field emission devices. PMID:26152895

  17. Efficient removal of herbicide 2,4-dichlorophenoxyacetic acid from water using Ag/reduced graphene oxide co-decorated TiO2 nanotube arrays.

    PubMed

    Tang, Yanhong; Luo, Shenglian; Teng, Yarong; Liu, Chengbin; Xu, Xiangli; Zhang, Xilin; Chen, Liang

    2012-11-30

    A new photocatalyst, Ag nanoparticles (NPs) and reduced graphene oxide (RGO) co-decorated TiO(2) nanotube arrays (NTs) (Ag/RGO-TiO(2) NTs), was designed and facilely produced by combining electrodeposition and photoreduction processes. The structures and properties of the photocatalysts were characterized. The ternary catalyst exhibited almost 100% photocatalytic removal efficiency of typical herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) from water under simulated solar light irradiation. The photodegradation rate toward 2,4-D over Ag/RGO-TiO(2) NTs is 11.3 times that over bare TiO(2) NTs. After 10 successive cycles with 1600 min of irradiation, Ag/RGO-TiO(2) NTs maintained as high 2,4-D removal efficiency as 97.3% with excellent stability and easy recovery, which justifies the photocatalytic system a promising application for herbicide removal from water.

  18. Synergistic effects of the aspect ratio of TiO2 nanowires and multi-walled carbon nanotube embedment for enhancing photovoltaic performance of dye-sensitized solar cells.

    PubMed

    Ahn, Ji Young; Kim, Ji Hoon; Moon, Kook Joo; Park, So Dam; Kim, Soo Hyung

    2013-08-07

    The existence of numerous interfacial boundaries among TiO2 nanoparticles (NPs) accumulated in the photoelectrode layer of dye-sensitized solar cells (DSSCs) hinders the effective transport of photogenerated electrons to an electrode. Therefore, as a replacement for TiO2 NPs, one-dimensional TiO2 nanowires (NWs) can be suggested to provide pathways for fast electron transport by significantly reducing the number of interfacial boundaries. In order to provide direct evidence for the better performance of such longer TiO2 NWs than shorter TiO2 NWs, we examine the effect of the controlled aspect ratio of the TiO2 NWs randomly accumulated in the photoelectrode layer on the photovoltaic performance of DSSCs. It is clearly found that longer TiO2 NWs significantly improve the electron transport by reducing the TiO2/dye/electrolyte interfacial contact resistance. Furthermore, the embedment of multi-walled carbon nanotubes (MWCNTs) as an effective charge transfer medium in longer TiO2 NWs is proposed in this study to promote more synergistic effects, which lead to significant improvements in the photovoltaic properties of DSSCs.

  19. A bilayer composite composed of TiO2-incorporated electrospun chitosan membrane and human extracellular matrix sheet as a wound dressing.

    PubMed

    Woo, Chang Hee; Choi, Young Chan; Choi, Ji Suk; Lee, Hee Young; Cho, Yong Woo

    2015-01-01

    We designed bilayer composites composed of an upper layer of titanium dioxide (TiO2)-incorporated chitosan membrane and a sub-layer of human adipose-derived extracellular matrix (ECM) sheet as a wound dressing for full-thickness wound healing. The dense and fibrous top layer, which aims to protect the wound from bacterial infection, was prepared by electrospinning of chitosan solution followed by immersion in TiO2 solution. The sponge-like sub-layer, which aims to promote new tissue regeneration, was prepared with acellular ECM derived from human adipose tissue. Using a modified drop plate method, there was a 33.9 and 69.6% reduction in viable Escherichia coli and Staphylococcus aureus on the bilayer composite, respectively. In an in vivo experiment using rats, the bilayer composites exhibited good biocompatibility and provided proper physicochemical and compositional cues at the wound site. Changes in wound size and histological examination of full-thickness wounds showed that the bilayer composites induced faster regeneration of granulation tissue and epidermis with less scar formation, than control wounds. Overall results suggest that the TiO2-incorporated chitosan/ECM bilayer composite can be a suitable candidate as a wound dressing, with an excellent inhibition of bacterial penetration and wound healing acceleration effects.

  20. Hydroxyapatite/gelatin functionalized graphene oxide composite coatings deposited on TiO2 nanotube by electrochemical deposition for biomedical applications

    NASA Astrophysics Data System (ADS)

    Yan, Yajing; Zhang, Xuejiao; Mao, Huanhuan; Huang, Yong; Ding, Qiongqiong; Pang, Xiaofeng

    2015-02-01

    Graphene oxide cross-linked gelatin was employed as reinforcement fillers in hydroxyapatite coatings by electrochemical deposition process on TiO2 nanotube arrays (TNs). The TNs were grown on titanium by electrochemical anodization in hydrofluoric electrolyte using constant voltage. Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Field emission scanning electron microscopy equipped with energy dispersive X-ray analysis and biological studies were used to characterize the coatings. The corrosion resistance of the coatings was also investigated by electrochemical method in simulated body fluid solution.

  1. Micro-solid phase equilibrium extraction with highly ordered TiO2 nanotube arrays: a new approach for the enrichment and measurement of organochlorine pesticides at trace level in environmental water samples.

    PubMed

    Zhou, Qingxiang; Huang, Yunrui; Xiao, Junping; Xie, Guohong

    2011-04-01

    Ordered TiO(2) nanotube arrays have been widely used in many fields such as photocatalysis, self-cleaning, solar cells, gas sensing, and catalysis. This present study exploited a new functional application of the ordered TiO(2) nanotube arrays. A micro-solid phase equilibrium extraction using ordered TiO(2) nanotube arrays was developed for the enrichment and measurement of organochlorine pesticides prior to gas chromatography-electron capture detection. Ordered TiO(2) nanotube arrays exhibited excellent merits on the pre-concentration of organochlorine pesticides and lower detection limits of 0.10, 0.10, 0.10, 0.098, 0.0076, 0.0097, 0.016, and 0.023 μg L(-1) for α-HCH, β-HCH, γ-HCH, δ-HCH, p,p'-DDE, p,p'-DDD, o,p'-DDT, and p,p'-DDT, respectively, were achieved. Four real water samples were used for validation, and the spiked recoveries were in the range of 78-102.8%. These results demonstrated that the developed micro-solid phase equilibrium extraction using ordered TiO(2) nanotube arrays would be very constructive and have a great beginning with a brand new prospect in the analysis of environmental pollutants.

  2. Supported noble metals on hydrogen-treated TiO2 nanotube arrays as highly ordered electrodes for fuel cells.

    PubMed

    Zhang, Changkun; Yu, Hongmei; Li, Yongkun; Gao, Yuan; Zhao, Yun; Song, Wei; Shao, Zhigang; Yi, Baolian

    2013-04-01

    Hydrogen-treated TiO2 nanotube (H-TNT) arrays serve as highly ordered nanostructured electrode supports, which are able to significantly improve the electrochemical performance and durability of fuel cells. The electrical conductivity of H-TNTs increases by approximately one order of magnitude in comparison to air-treated TNTs. The increase in the number of oxygen vacancies and hydroxyl groups on the H-TNTs help to anchor a greater number of Pt atoms during Pt electrodeposition. The H-TNTs are pretreated by using a successive ion adsorption and reaction (SIAR) method that enhances the loading and dispersion of Pt catalysts when electrodeposited. In the SIAR method a Pd activator can be used to provide uniform nucleation sites for Pt and leads to increased Pt loading on the H-TNTs. Furthermore, fabricated Pt nanoparticles with a diameter of 3.4 nm are located uniformly around the pretreated H-TNT support. The as-prepared and highly ordered electrodes exhibit excellent stability during accelerated durability tests, particularly for the H-TNT-loaded Pt catalysts that have been annealed in ultrahigh purity H2 for a second time. There is minimal decrease in the electrochemical surface area of the as-prepared electrode after 1000 cycles compared to a 68 % decrease for the commercial JM 20 % Pt/C electrode after 800 cycles. X-ray photoelectron spectroscopy shows that after the H-TNT-loaded Pt catalysts are annealed in H2 for the second time, the strong metal-support interaction between the H-TNTs and the Pt catalysts enhances the electrochemical stability of the electrodes. Fuel-cell testing shows that the power density reaches a maximum of 500 mWcm(-2) when this highly ordered electrode is used as the anode. When used as the cathode in a fuel cell with extra-low Pt loading, the new electrode generates a specific power density of 2.68 kWg(Pt) (-1) . It is indicated that H-TNT arrays, which have highly ordered nanostructures, could be used as ordered electrode supports.

  3. Domain-confined catalytic soot combustion over Co3O4 anchored on a TiO2 nanotube array catalyst prepared by mercaptoacetic acid induced surface-grafting.

    PubMed

    Ren, Jiale; Yu, Yifu; Dai, Fangfang; Meng, Ming; Zhang, Jing; Zheng, Lirong; Hu, Tiandou

    2013-12-21

    Herein, we introduce a specially designed domain-confined macroporous catalyst, namely, the Co3O4 nanocrystals anchored on a TiO2 nanotube array catalyst, which was synthesized by using the mercaptoacetic acid induced surface-grafting method. This catalyst exhibits much better performance for catalytic soot combustion than the conventional TiO2 powder supported one in gravitational contact mode (GMC).

  4. Open-ended TiO2 nanotubes formed by two-step anodization and their application in dye-sensitized solar cells.

    PubMed

    Yip, Cho-Tung; Guo, Min; Huang, Haitao; Zhou, Limin; Wang, Yu; Huang, Chuanjun

    2012-01-21

    We demonstrate a simple method to fabricate open-ended TiO(2) nanotube (NT) based dye-sensitized solar cells (DSSCs), where the NTs are attached to either TiO(2) nanorods (NRs) grown on fluorine-doped tin oxide (FTO) or FTO directly by nanoparticles (NPs). A completely hole-through TiO(2) NT layer is fabricated via a two-step anodization with heat treatment immediately after the first anodization. DSSCs with the open-ended NTs show better photovoltaic performance than those with close-ended NTs, due to the enhanced charge transport in the open-ended structure. Under optimum conditions, DSSCs fabricated with the open-ended NT layer exhibit a short circuit current density (J(sc)) of 19.10 mA cm(-2), an open circuit voltage (V(oc)) of 0.68 V, a fill factor (FF) of 0.49, and a power conversion efficiency (eff) of 6.3%.

  5. Self-assembly graphitic carbon nitride quantum dots anchored on TiO2 nanotube arrays: An efficient heterojunction for pollutants degradation under solar light.

    PubMed

    Su, Jingyang; Zhu, Lin; Geng, Ping; Chen, Guohua

    2016-10-05

    In this study, an efficient heterojunction was constructed by anchoring graphitic carbon nitride quantum dots onto TiO2 nanotube arrays through hydrothermal reaction strategy. The prepared graphitic carbon nitride quantum dots, which were prepared by solid-thermal reaction and sequential dialysis process, act as a sensitizer to enhance light absorption. Furthermore, it was demonstrated that the charge transfer and separation in the formed heterojunction were significantly improved compared with pristine TiO2. The prepared heterojunction was used as a photoanode, exhibiting much improved photoelectrochemical capability and excellent photo-stability under solar light illumination. The photoelectrocatalytic activities of prepared heterojunction were demonstrated by degradation of RhB and phenol in aqueous solution. The kinetic constants of RhB and phenol degradation using prepared photoelectrode are 2.4 times and 4.9 times higher than those of pristine TiO2, respectively. Moreover, hydroxyl radicals are demonstrated to be dominant active radicals during the pollutants degradation.

  6. Plasmonic gold nanocrystals coupled with photonic crystal seamlessly on TiO2 nanotube photoelectrodes for efficient visible light photoelectrochemical water splitting.

    PubMed

    Zhang, Zhonghai; Zhang, Lianbin; Hedhili, Mohamed Nejib; Zhang, Hongnan; Wang, Peng

    2013-01-09

    A visible light responsive plasmonic photocatalytic composite material is designed by rationally selecting Au nanocrystals and assembling them with the TiO(2)-based photonic crystal substrate. The selection of the Au nanocrystals is so that their surface plasmonic resonance (SPR) wavelength matches the photonic band gap of the photonic crystal and thus that the SPR of the Au receives remarkable assistance from the photonic crystal substrate. The design of the composite material is expected to significantly increase the Au SPR intensity and consequently boost the hot electron injection from the Au nanocrystals into the conduction band of TiO(2), leading to a considerably enhanced water splitting performance of the material under visible light. A proof-of-concept example is provided by assembling 20 nm Au nanocrystals, with a SPR peak at 556 nm, onto the photonic crystal which is seamlessly connected on TiO(2) nanotube array. Under visible light illumination (>420 nm), the designed material produced a photocurrent density of ~150 μA cm(-2), which is the highest value ever reported in any plasmonic Au/TiO(2) system under visible light irradiation due to the photonic crystal-assisted SPR. This work contributes to the rational design of the visible light responsive plasmonic photocatalytic composite material based on wide band gap metal oxides for photoelectrochemical applications.

  7. Immobilization of Pt Nanoparticles via Rapid and Reusable Electropolymerization of Dopamine on TiO2 Nanotube Arrays for Reversible SERS Substrates and Nonenzymatic Glucose Sensors.

    PubMed

    Cai, Jingsheng; Huang, Jianying; Ge, Mingzheng; Iocozzia, James; Lin, Zhiqun; Zhang, Ke-Qin; Lai, Yuekun

    2017-03-10

    Inspired by mussel-adhesion phenomena in nature, polydopamine (PDA) coatings are a promising route to multifunctional platforms for decorating various materials. The typical self-polymerization process of dopamine is time-consuming and the coatings of PDA are not reusable. Herein, a reusable and time-saving strategy for the electrochemical polymerization of dopamine (EPD) is reported. The PDA layer is deposited on vertically aligned TiO2 nanotube arrays (NTAs). Owing to the abundant catechol and amine groups in the PDA layer, uniform Pt nanoparticles (NPs) are deposited onto the TiO2 NTAs and can effectively prevent the recombination of electron-hole pairs generated from photo-electrocatalysis and transfer the captured electrons to participate in the photo-electrocatalytic reaction process. Compared with pristine TiO2 NTAs, the as-prepared Pt@TiO2 NTA composites exhibit surface-enhanced Raman scattering sensitivity for detecting rhodamine 6G and display excellent UV-assisted self-cleaning ability, and also show promise as a nonenzymatic glucose biosensor. Furthermore, the mussel-inspired electropolymerization strategy and the fast EPD-reduced nanoparticle decorating process presented herein can be readily extended to various functional substrates, such as conductive glass, metallic oxides, and semiconductors. It is the adaptation of the established PDA system for a selective, robust, and generalizable sensing system that is the emphasis of this work.

  8. Fast photoelectro-reduction of Cr(VI) over MoS2@TiO2 nanotubes on Ti wire.

    PubMed

    Yang, Lixia; Zheng, Xutong; Liu, Ming; Luo, Shenglian; Luo, Yan; Li, Guifa

    2017-01-30

    A stable MoS2 nanosheets@TiO2 NTAs composite was prepared via a simple hydrothermal process. Few-layer MoS2 nanosheets distributed on the TiO2 nanotube top surface and the inner walls rather than filling in the tubes, allowing abundant tubular channels open to environment and benefiting for efficient mass transport. Photocatalytic (PE) and photoelectrocatalytic (PEC) performance of the composite were evaluated on Cr(VI) reduction, with variable low molecule weight organic acids (LOAs) added as sacrificial electron donor to form a charge-transfer-complex (CTC) between LOAs and TiO2/MoS2, which is sensitive to the visible light illumination and could induce the photo-reduction of Cr(VI) and photo-oxidation of LOAs. The overall trend of Cr(VI) PEC rates are in the order as: L(+)-Tartaric acid>oxalic acid>citric acid>malic acid>amber acid, which is 103.9>62.5>31.2>21.6>2.5mg/Lmin(-1)cm(-2), respectively. The improved catalytic performance and excellent stability of the composite can be attributed to the abundant active adsorption and reaction sites on MoS2 nanosheets and the formation of a heterojunction between TiO2 and MoS2. Moreover, the appropriate application of LOAs and voltage also have a great contribution to the utilization of sunlight and efficient separation of photogenerated carriers.

  9. All solid-state solar cells based on CH3NH3PbI3-sensitized TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Yang, Xiuchun; Liu, Wei; Ren, Peng

    2016-09-01

    TiO2 nanotube arrays (TiO2 NTAs) were firstly used as photoanode in methylammonium lead iodide (CH3NH3PbI3) perovskite/TiO2 NTAs heterojunction solar cell, where CH3NH3PbI3 functions as both light absorber and hole conductor. The composition, structure and photoelectrochemical properties of the as-prepared samples were characterized by x-ray diffractometer (XRD), field-emission scanning electron microscope (FE-SEM), ultraviolet-visible (UV-vis) spectrophotometer and electrochemical workstation. The results indicate that the as-prepared CH3NH3PbI3 belongs to the cubic crystal system, and TiO2 NTAs sensitized by 0.3 M CH3NH3I and PbI2 exhibit the best photoelectrochemical properties with an open-circuit voltage of 0.422 V and a short-circuit current density of 173.4 μA cm-2. The EIS result shows that the extremely large resistance at CH3NH3PbI3/FTO interface contributes to the low current density of the perovskite solar cell.

  10. Amplified quenching of electrochemiluminescence from CdS sensitized TiO2 nanotubes by CdTe-carbon nanotube composite for detection of prostate protein antigen in serum.

    PubMed

    Tian, Chun-Yuan; Zhao, Wei-Wei; Wang, Jing; Xu, Jing-Juan; Chen, Hong-Yuan

    2012-07-07

    This work reports an ECL immunoassay method for ultrasensitive detection of prostate protein antigen (PSA), by remarkably efficient energy-transfer induced electrochemiluminescence (ECL) quenching from the CdS nanoparticles (NPs) sensitized TiO(2) nanotube array (CdS-TiO(2) NTs) to the activated CdTe NPs functionalized multi-wall carbon nanotubes (CdTe-MWNTs) composite. The coupling of TiO(2) and CdS NPs results in a cathodic ECL intensity 14.7 times stronger than that of the pure TiO(2) NTs electrode, which could be efficiently quenched by the CdTe-MWNTs. The enhanced mechanism of TiO(2) NTs ECL by CdS NPs was studied in detail by cyclic voltammetry and ECL spectroscopy. The strong absorption of the CdTe-MWNTs in the wavelength range of 400-800 nm renders them highly efficient for ECL quenching labeled on anti-PSA antibody. Based on a sandwich structure, we developed an ECL immunoassay method for the sensitive and selective detection of PSA. The ECL intensity decrement was logarithmically related to the concentration of the PSA in the range of 1.0 fg mL(-1) to 10 pg mL(-1) with a detection limit of 1 fg mL(-1). Human serum samples were then tested using the proposed immunoassay with excellent correlations, suggesting that the proposed immunoassay method is of great promise in clinical screening of cancer biomarkers.

  11. Nanomolar concentrations determination of hydrazine by a modified carbon paste electrode incorporating TiO2nanoparticles

    NASA Astrophysics Data System (ADS)

    Mazloum-Ardakani, Mohammad; Taleat, Zahra; Beitollahi, Hadi; Naeimi, Hossein

    2011-04-01

    In the present paper, the use of a carbon paste electrode modified by quinizarine (QZ) and TiO2nanoparticles prepared by a simple and rapid method was described. The heterogeneous electron-transfer properties of quinizarine coupled to TiO2nanoparticles at a carbon paste electrode was investigated using cyclic voltammetry and chronoamperometry in aqueous buffer solutions. The modified electrode showed excellent character for the electrocatalytic oxidization of hydrazine (HZ). Differential pulse voltammetric peak currents of HZ increased linearly with their concentrations at the range of 0.5 µM to 1900.0 µM and the detection limit (2σ) was determined to be 77 nM. Finally, this method was used for the determination of HZ in water samples, using a standard addition method.

  12. Nanomolar concentrations determination of hydrazine by a modified carbon paste electrode incorporating TiO2 nanoparticles.

    PubMed

    Mazloum-Ardakani, Mohammad; Taleat, Zahra; Beitollahi, Hadi; Naeimi, Hossein

    2011-04-01

    In the present paper, the use of a carbon paste electrode modified by quinizarine (QZ) and TiO(2) nanoparticles prepared by a simple and rapid method was described. The heterogeneous electron-transfer properties of quinizarine coupled to TiO(2) nanoparticles at a carbon paste electrode was investigated using cyclic voltammetry and chronoamperometry in aqueous buffer solutions. The modified electrode showed excellent character for the electrocatalytic oxidization of hydrazine (HZ). Differential pulse voltammetric peak currents of HZ increased linearly with their concentrations at the range of 0.5 µM to 1900.0 µM and the detection limit (2σ) was determined to be 77 nM. Finally, this method was used for the determination of HZ in water samples, using a standard addition method.

  13. Electrochemical sensor for detection of hydrazine based on Au@Pd core-shell nanoparticles supported on amino-functionalized TiO2 nanotubes.

    PubMed

    Chen, Xianlan; Liu, Wei; Tang, Lele; Wang, Jian; Pan, Haibo; Du, Min

    2014-01-01

    In this paper, we reported a simple strategy for synthesizing well-defined TiO2NTs-Au@Pd hybrid nanostructures with prior TiO2 nanotube functionalization (F-TiO2NTs). TiO2NTs with larger surface area (BET surface area is 184.9m(2)g(-1)) were synthesized by hydrothermal method, and the NTs are anatase phase with a range of 2-3μm in length and 30-50nm in diameter after calcined at 400°C for 3h. 3-Aminopropyl-trimethoxysilane (APTMS) as a coupling agent was reacted with the surface hydroxyl groups as anchoring sites for flower-shaped bimetallic Au@Pd nanostructures, self-assembling amine functionality on the surface of TiO2NTs. Note that two faces at the interface between F-TiO2NTs with (004) plane and Au@Pd nanostructures with (111) one of cubic Au and Pd nanoparticles are compatible, benefiting to the charge transfer between two components due to their crystalline coordination. The results showed that as-prepared F-TiO2NTs-Au@Pd hybrid nanostructures modified glassy carbon electrode (GCE) exhibits high electrocatalytic activity toward hydrazine (N2H4) at low potential and a linear response from 0.06 to 700μM with the detection limit for N2H4 was found to be 1.2×10(-8)M (S/N=3). Based on scan rate effect during the hydrazine oxidation, it indicates that the number of electrons transferred in the rate-limiting step is 1, and a transfer coefficient (α) is estimated as 0.73. The self-assembled F-TiO2NTs-Au@Pd hybrid nanostructures as enhanced materials present excellent electrocatalytic activity, fast response, highly sensitive and have a promising application potential in nonenzymatic sensing.

  14. Photoelectrochemical Performance of Quantum dot-Sensitized TiO2 Nanotube Arrays: a Study of Surface Modification by Atomic Layer Deposition Coating.

    PubMed

    Zhou, Quan; Zhou, Junchen; Zeng, Min; Wang, Guizhen; Chen, Yongjun; Lin, Shiwei

    2017-12-01

    Although CdS and PbS quantum dot-sensitized TiO2 nanotube arrays (TNTAs/QDs) show photocatalytic activity in the visible-light region, the low internal quantum efficiency and the slow interfacial hole transfer rate limit their applications. This work modified the surface of the TNTAs/QDs photoelectrodes with metal-oxide overlayers by atomic layer deposition (ALD), such as coating Al2O3, TiO2, and ZnO. The ALD deposition of all these overlayers can apparently enhance the photoelectrochemical performance of the TNTAs/QDs. Under simulated solar illumination, the maximum photocurrent densities of the TNTAs/QDs with 10 cycles ZnO, 25 cycles TiO2, and 30 cycles Al2O3 overlayers are 5.0, 4.3, and 5.6 mA/cm(2) at 1.0 V (vs. SCE), respectively. The photoelectrode with Al2O3 overlayer coating presents the superior performance, whose photocurrent density is 37 times and 1.6 times higher than those of the TNTAs and TNTAs/QDs, respectively. Systematic examination of the effects of various metal-oxide overlayers on the photoelectrochemical performance indicates that the enhancement by TiO2 and ZnO overcoatings can only ascribed to the decrease of the interfacial charge transfer impedance, besides which Al2O3 coating can passivate the surface states and facilitate the charge transfer kinetics. These results could be helpful to develop high-performance photoelectrodes in the photoelectrochemical applications.

  15. Effect of phosphonate monolayer adsorbate on the microwave photoresponse of TiO2 nanotube membranes mounted on a planar double ring resonator

    NASA Astrophysics Data System (ADS)

    Zarifi, Mohammad H.; Farsinezhad, Samira; Wiltshire, Benjamin D.; Abdorrazaghi, Mohammad; Mahdi, Najia; Kar, Piyush; Daneshmand, Mojgan; Shankar, Karthik

    2016-09-01

    In this study, the effects of a phosphonate molecular monolayer adsorbed on the surface of a free-standing self-organized TiO2 nanotube membrane, on the microwave photoresponse of the membrane are presented. This phenomenon is monitored using planar microwave sensors. A double ring resonator is utilized to monitor the permittivity and conductivity variation on the monolayer coated membrane and the sensor environment separately. It is shown that the rise time and subsequent decay of the amplitude (A), resonance frequency (f 0) and quality factor (Q) of the resonator depend on the existence and the type of the monolayer coating the membrane. Three different monolayers of n-decylphosphonic acid (DPA), 1H, 1H‧, 2H, 2H‧-perfluorodecyl phosphonic acid (PFDPA) and 16-phosphonohexadecanoic acid adsorbed on the titania nanotube membrane are investigated while monitoring their microwave properties during the illumination time period and in the relaxation period, which demonstrate different behavior in comparison to each other and to the bare nanotube membrane layer. The effect of humidity on the TiO2 nanotube membrane with and without different monolayers is also studied and the results demonstrate distinguishable microwave responses. While each of the monolayer-coated membranes exhibited an attenuation of the photo-induced change in A, f 0 and Q with respect to the bare membrane, PFDPA-coated membranes showed the smallest relative change in the monitored microwave parameters upon ultraviolet illumination and upon the introduction of different levels of humidity. These effects are explained on the basis of surface trap passivation by the monolayers as well as the hydrophobicity of the monolayers. Our work also shows how the interactions of self-assembled monolayers with charge carriers and surface states on metal oxides may be used to indirectly sense their presence through measurement of the microwave response.

  16. Study of TiO2 nano-tubes using electrochemical anodization method for applications in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Ghani, T.; Mujahid, M.; Mehmood, M.; Shahzad, Q.

    2016-08-01

    TiO2 nano-tubes are getting strong attraction in many fields due to their unique properties. They are important in biomedical application, Dye sensitized solar cells, sensor and photocatalys is applications, etc. Our prime interest is to grow these tubes for dye-sensitized solar cells with high conversion efficiency and low production cost. In this research, we have synthesized TiO2 naonotubes by anodizing 25 µm thick titanium foil at 40V using two-step anodization method. The electrolyte used is the ethylene glycol with varying concentration of NH4F and fixed concentration of deionized water. Effect of different concentrations of the electrolyte on tube crystal structure has been studied. It is observed that crystallinity increases with increased concentration of fluoride ions. It is found that two-stepanodization method results in more crystalline and open structures. Scanning electron microscopy is utilized to study the surface morphology and tubes growth, whereas observation of the crystal structure of nano-tubes is made by X-ray diffraction.

  17. Enhanced performance of reversely transferred, doubly open-ended TiO2 nanotube arrays for front-illuminated dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kim, Hyunsoo; Lee, Soo-Yong; Kim, Jae-Hong; Ahn, Kwang-Soon; Kang, Soon-Hyung

    2016-01-01

    Doubly open-ended conventional TiO2 nanotube arrays (Type I) and nanoporous-layer-covered nanotube arrays (Type II) were transferred to transparent fluorine-doped tin oxides (FTOs) for front-illuminated dye-sensitized solar cells (DSSCs). FTO/Type II exhibited a long electron lifetime ( τ e ) and rapid electron transport compared to FTO/Type I because of the reduced surface defect-state-mediated recombination rate. In particular, Type II transferred reversely to the FTO (FTO/Type II-rev) had beneficial geometric effects, leading to a decrease in pore size from the bottom to the top and a nanoporous TiO2 thin bottom layer. These enabled more effective light scattering near the FTO and facilitated lateral electron movement toward the FTO, leading to a shortened electron pathway and a reduced recombination rate. The significantly enhanced electron lifetime and the shortened electron transit time of the FTO/Type II-rev improved the charge collection efficiency significantly. Furthermore, the enhanced light scattering increased the light harvesting efficiency. These beneficial geometric effects of FTO/Type II-rev contributed to the greatly enhanced overall cell efficiency (7.61%) of the DSSC compared to the DSSCs with FTO/Type I (5.27%) and FTO/Type II (6.65%).

  18. A strategy to reduce the angular dependence of a dye-sensitized solar cell by coupling to a TiO2 nanotube photonic crystal.

    PubMed

    Guo, Min; Xie, Keyu; Liu, Xiaolin; Wang, Yu; Zhou, Limin; Huang, Haitao

    2014-11-07

    Almost all types of solar cells suffer from a decreased power output when the incident light is tilted away from normal since the incident intensity generally follows a cosine law of the incident angle. Making use of the blue shift nature of the Bragg position of a TiO2 nanotube photonic crystal (NT PC) under oblique incidence, we demonstrate experimentally that the use of the NT PC can partially compensate the cosine power loss of a dye-sensitized solar cell (DSSC). The strategy used here is to purposely choose the Bragg position of the NT PC to be at the longer wavelength side of the dye absorption peak. When the incident light is tilted, the blue shift of the Bragg position results in more overlap with the dye absorption peak, generating a higher efficiency that partially compensates the reduced photon flux due to light inclination. Moreover, the unique structure of the vertically aligned TiO2 nanotubes contributes an additional scattering effect when the incident light is tilted. As a result, the power output of a DSSC coupled with the NT PC layer shows a much flatter angular dependence than a DSSC without the NT PC. At all the incident angles, the DSSC coupled with the NT PC layer also shows a higher power conversion efficiency than the one without. The concept of using NT PC to mitigate the angular dependence of DSSCs can be easily extended to many other optoelectronic devices that are irradiance sensitive.

  19. Pt-Decorated g-C3N4/TiO2 Nanotube Arrays with Enhanced Visible-Light Photocatalytic Activity for H2 Evolution.

    PubMed

    Gao, Zhi-Da; Qu, Yong-Fang; Zhou, Xuemei; Wang, Lei; Song, Yan-Yan; Schmuki, Patrik

    2016-06-01

    Aligned TiO2 nanotube layers (TiNTs) grown by self-organizing anodization of a Ti-substrate in a fluoride-based electrolyte were decorated with graphitic-phase C3N4 (g-C3N4) via a facile chemical vapor deposition approach. In comparison with classical TiO2 nanotubes (anatase), the g-C3N4/TiNTs show an onset of the photocurrent at 2.4 eV (vs. 3.2 eV for anatase) with a considerably high photocurrent magnitude in the visible range. After further decoration with Pt nanoparticles, we obtained a visible-light responsive platform that showed, compared with g-C3N4-free TiNTs, a strong enhancement for photoelectrochemical and bias-free H2 evolution (15.62 μLh(-1) cm(-2)), which was almost a 98-fold increase in the H2 production rate of TiNTs (0.16 μLh(-1) cm(-2)). In a wider context, the g-C3N4-combined 3 D nanoporous/nanotubular structure thus provides a platform with significant visible-light response in photocatalytic applications.

  20. Improving photoelectrochemical performance on quantum dots co-sensitized TiO2 nanotube arrays using ZnO energy barrier by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Zeng, Min; Zeng, Xi; Peng, Xiange; Zhu, Zhuo; Liao, Jianjun; Liu, Kai; Wang, Guizhen; Lin, Shiwei

    2016-12-01

    PbS and CdS quantum dots (QDs) have been deposited onto TiO2 nanotube arrays (TNTAs) in turn via a sonication-assisted successive ionic layer adsorption and reaction method. This method could uniformly decorate TNTAs with QDs, avoiding QDs aggregation at the mouth of TiO2 nanotube. The loading amounts of QDs on TNTAs could be controlled by adjusting the TNTAs length. Under one sun illumination, the QDs co-sensitized TNTAs (TNTAs/QDs) with the length of about 2.4 μm displayed the highest photocurrent of 4.32 mA cm-2, which is 27 times higher than that of the bare TNTAs. Introduction of a thin ZnO energy barrier by atomic layer deposition (ALD) between the TNTAs and QDs can further improve the photocurrent of TNTAs/QDs. And the TNTAs/QDs with 10 ALD cycles of ZnO interlayer exhibits the highest photocurrent of 5.24 mA cm-2 and best photoconversion efficiency of 4.9%, a more than 20% enhancement over the bare TNTAs/QDs. Such enhanced photoelectrochemical performance may be ascribed to the increased amounts of QDs on the TNTAs due to the introduction of ZnO interlayer. The benefits of ALD layers play a crucial role in development and optimization of high-performance photoelectrodes in the near future.

  1. Determination of trace organophosphorus pesticides in water samples with TiO2 nanotubes cartridge prior to GC-flame photometric detection.

    PubMed

    Huang, Yunrui; Zhou, Qingxiang; Xiao, Junping; Xie, Guohong

    2010-07-01

    This article described a new method for the sensitive determination of organophosphorus pesticides in water samples using SPE in combination with GC-flame photometric detection. In the procedure of method development, TiO(2) nanotubes were used as SPE adsorbents for the enrichment of organophosphorus pesticides from water samples. Several factors, such as eluent and its volume, sample pH, sample volume, sample flow rate, and concentration of humic acid, were optimized. Under the optimal conditions, the proposed method had good linear ranges as 0.1-40 microg/L for each of them, LOD of 0.11, 0.014, and 0.0025 microg/L, and LOQs of 0.37, 0.047, and 0.0083 microg/L for chlorpyrifos, phorate, and methyl parathion, respectively. The proposed method was validated with real environmental water samples and the spiked recoveries were over the range of 86.5-115.1%. All these results indicated that TiO(2) nanotubes, as a new SPE adsorbent, would be used widespread for the preconcentration and determination of environmental pollutants in the future.

  2. Pt‐Decorated g‐C3N4/TiO2 Nanotube Arrays with Enhanced Visible‐Light Photocatalytic Activity for H2 Evolution

    PubMed Central

    Gao, Zhi‐Da; Qu, Yong‐Fang; Zhou, Xuemei; Wang, Lei

    2016-01-01

    Abstract Aligned TiO2 nanotube layers (TiNTs) grown by self‐organizing anodization of a Ti‐substrate in a fluoride‐based electrolyte were decorated with graphitic‐phase C3N4 (g‐C3N4) via a facile chemical vapor deposition approach. In comparison with classical TiO2 nanotubes (anatase), the g‐C3N4/TiNTs show an onset of the photocurrent at 2.4 eV (vs. 3.2 eV for anatase) with a considerably high photocurrent magnitude in the visible range. After further decoration with Pt nanoparticles, we obtained a visible‐light responsive platform that showed, compared with g‐C3N4‐free TiNTs, a strong enhancement for photoelectrochemical and bias‐free H2 evolution (15.62 μLh−1 cm−2), which was almost a 98‐fold increase in the H2 production rate of TiNTs (0.16 μLh−1 cm−2). In a wider context, the g‐C3N4‐combined 3 D nanoporous/nanotubular structure thus provides a platform with significant visible‐light response in photocatalytic applications. PMID:27891298

  3. Plasmonic silver quantum dots coupled with hierarchical TiO2 nanotube arrays photoelectrodes for efficient visible-light photoelectrocatalytic hydrogen evolution.

    PubMed

    Lian, Zichao; Wang, Wenchao; Xiao, Shuning; Li, Xin; Cui, Yingying; Zhang, Dieqing; Li, Guisheng; Li, Hexing

    2015-06-12

    A plasmonic Ag/TiO2 photocatalytic composite was designed by selecting Ag quantum dots (Ag QDs) to act as a surface plasmon resonance (SPR) photosensitizer for driving the visible-light driven photoelectrocatalytic hydrogen evolution. Vertically oriented hierarchical TiO2 nanotube arrays (H-TiO2-NTAs) with macroporous structure were prepared through a two-step method based on electrochemical anodization. Subsequently, Ag QDs, with tunable size (1.3-21.0 nm), could be uniformly deposited on the H-TiO2 NTAs by current pulsing approach. The unique structure of the as-obtained photoelectrodes greatly improved the photoelectric conversion efficiency. The as-obtained Ag/H-TiO2-NTAs exhibited strong visible-light absorption capability, high photocurrent density, and enhanced photoelectrocatalytic (PEC) activity toward photoelectrocatalytic hydrogen evolution under visible-light irradiation (λ>420 nm). The enhancement in the photoelectric conversion efficiency and activity was ascribed to the synergistic effects of silver and the unique hierarchical structures of TiO2 nanotube arrays, strong SPR effect, and anti-shielding effect of ultrafine Ag QDs.

  4. Antifungal activity of Ag:hydroxyapatite thin films synthesized by pulsed laser deposition on Ti and Ti modified by TiO2 nanotubes substrates

    NASA Astrophysics Data System (ADS)

    Eraković, S.; Janković, A.; Ristoscu, C.; Duta, L.; Serban, N.; Visan, A.; Mihailescu, I. N.; Stan, G. E.; Socol, M.; Iordache, O.; Dumitrescu, I.; Luculescu, C. R.; Janaćković, Dj.; Miškovic-Stanković, V.

    2014-02-01

    Hydroxyapatite (HA) is a widely used biomaterial for implant thin films, largely recognized for its excellent capability to chemically bond to hard tissue inducing the osteogenesis without immune response from human tissues. Nowadays, intense research efforts are focused on development of antimicrobial HA doped thin films. In particular, HA doped with Ag (Ag:HA) is expected to inhibit the attachment of microbes and contamination of metallic implant surface. We herewith report on nano-sized HA and Ag:HA thin films synthesized by pulsed laser deposition on pure Ti and Ti modified with 100 nm diameter TiO2 nanotubes (fabricated by anodization of Ti plates) substrates. The HA-based thin films were characterized by SEM, AFM, EDS, FTIR, and XRD. The cytotoxic activity was tested with HEp2 cells against controls. The antifungal efficiency of the deposited layers was tested against the Candida albicans and Aspergillus niger strains. The Ti substrates modified with TiO2 nanotubes covered with Ag:HA thin films showed the highest antifungal activity.

  5. Enhancement in Sustained Release of Antimicrobial Peptide from Dual-Diameter-Structured TiO2 Nanotubes for Long-Lasting Antibacterial Activity and Cytocompatibility.

    PubMed

    Zhang, Yanni; Zhang, Lan; Li, Bo; Han, Yong

    2017-03-22

    Novel films on Ti-based orthopedic implants for localized antimicrobial delivery, which comprises dual-diameter TiO2 nanotubes with the inner layers of compact and fluorine-free oxide tightly bonding to Ti, were formed by voltage-increased anodization with F(-) sedimentation procedure. The nanotubes were closely aligned and structured with upper 35 and 70 nm diametric tubes as nanocaps, respectively, and the underlying 140 nm diametric tubes as nanoreservoirs. Followed by loading ponericin G1 (a kind of antimicrobial peptide (AMP)) into the dual-diameter nanotubes with vacuum-assisted physisorption, the resultant films were investigated for loading efficiency and release kinetics of AMP, antibacterial activity against Staphylococcus aureus, and osteoblastic compatibility, together with the AMP-loaded single-diameter (140 nm) nanotube film. The loaded films had no statistical difference in the loading efficiency of AMP and revealed burst release within 6 h followed by steady release of AMP in phosphate-buffered solution. At day 42, almost all of AMP was released from the single-diameter nanotube film. However, the dual-diameter nanotube films loaded with AMP still showed sustained release at least up to 60 days, and the sustained efficacy was enhanced with decreasing diameter of nanocaps. In the case of nominal AMP loading amount of 125 μg, the resultant 35 nm capped dual-diameter nanotube film exhibited significant short- and long-term (even for 49 days) antibacterial activity not only against planktonic bacteria, which is ascribed to the release-killing efficacy of AMP, but also against adhered bacteria, which is ascribed to the AMP-derived killing efficacy and the nanocaps-derived adhesion resistance. Moreover, this loaded film presented cytocompatibility comparative to that of Ti but higher than that of the other AMP-loaded films. Increasing the nominal loading amount of AMP to 200 μg improved antibacterial activity but gave rise to obvious cytotoxicity of the

  6. TiO2 nanotube arrays deposited on Ti substrate by anodic oxidation and their potential as a long-term drug delivery system for antimicrobial agents

    NASA Astrophysics Data System (ADS)

    Moseke, Claus; Hage, Felix; Vorndran, Elke; Gbureck, Uwe

    2012-05-01

    Nanotube arrays on medical titanium surfaces were fabricated by two different anodization methods and their potential for storage and release of antimicrobial substances was evaluated. The treatment of the Ti surfaces in fluoride containing electrolytes on water as well as on polyethylene glycol basis led to the formation of TiO2 nanotubes with up to 6.54 μm length and average diameters of up to 160 nm. Drug release experiments with the model antibiotic vancomycin and with antibacterial silver ions showed that the increased surface area of the anodized samples enabled them to be loaded with up to 450% more active agent than the untreated Ti surfaces. Significant surface-dependent differences in the release kinetics of vancomycin were observed. In comparison to surfaces anodized in an aqueous electrolyte, the release of the antibiotic from surfaces anodized in an electrolyte based on ethylene glycol was significantly retarded, with a release of noticeable amounts over a period of more than 300 days. Loading of nanotube surfaces fabricated in aqueous electrolyte with silver ions revealed increased amounts of adsorbed silver by up to 230%, while the release kinetics showed significant differences in comparison to untreated Ti. It was concluded that nanotube arrays on favored medical implant materials have a high potential for loading with antimicrobial agents and also provide the possibility of tailored release kinetics by variation of anodization parameters.

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

    PubMed

    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.

  8. High-Performance and Stable Gel-State Dye-Sensitized Solar Cells Using Anodic TiO2 Nanotube Arrays and Polymer-Based Gel Electrolytes.

    PubMed

    Seidalilir, Zahra; Malekfar, Rasoul; Wu, Hui-Ping; Shiu, Jia-Wei; Diau, Eric Wei-Guang

    2015-06-17

    Highly ordered and vertically oriented TiO2 nanotube (NT) arrays were synthesized with potentiostatic anodization of Ti foil and applied to fabricate gel-state dye-sensitized solar cells (DSSCs). The open structure of the TiO2 NT facilitates the infiltration of the gel-state electrolyte; their one-dimensional structural feature provides effective charge transport. TiO2 NTs of length L=15-35 μm were produced on anodization for periods of t=5-15 h at a constant voltage of 60 V, and sensitized with N719 for photovoltaic characterization. A commercially available copolymer, poly(methyl methacrylate-co-ethyl acrylate) (PMMA-EA), served as a gelling agent to prepare a polymer-gel electrolyte (PGE) for DSSC applications. The PGE as prepared exhibited a maximum conductivity of 4.58 mS cm(-1) with PMMA-EA (7 wt %). The phase transition temperature (Tp) of the PGE containing PMMA-EA at varied concentrations was determined on the basis of the viscosities measured at varied temperatures. Tp increased with increasing concentration of PMMA-EA. An NT-DSSC with L=30 μm assembled using a PGE containing PMMA-EA (7 wt %) exhibited an overall power conversion efficiency (PCE) of 6.9%, which is comparable with that of a corresponding liquid-type device, PCE=7.1%. Moreover, the gel-state NT-DSSC exhibited excellent thermal and light-soaking enduring stability: the best device retained ∼90% of its initial efficiency after 1000 h under 1 sun of illumination at 50 °C, whereas its liquid-state counterpart decayed appreciably after light soaking for 500 h.

  9. Probing the charge recombination in rGO decorated mixed phase (anatase-rutile) TiO2 multi-leg nanotubes

    NASA Astrophysics Data System (ADS)

    Rambabu, Y.; Jaiswal, Manu; Roy, Somnath C.

    2016-11-01

    Recombination of photo-generated charges is one of the most significant challenges in designing efficient photo-anode for photo electrochemical water oxidation. In the case of TiO2, mixed phase (anatase-rutile) junctions often shown to be more effective in suppressing electron-hole recombination compared to a single (anatase or rutile) phase. Here, we report the study of bulk and surface recombination process in TiO2 multi-leg nanotube (MLNTs) anatase-rutile (A-R) junctions decorated with reduced graphene oxide (rGO) layers, through an analysis of the photo-current and impedance characteristics. To quantify the charge transport/transfer process involved in these junctions, holes arriving at the interface of semiconductor/electrolyte were collected by adding H2O2 to the electrolyte. This enabled us to interpret the bulk and surface recombination process involved in anatase/rutile/rGO junctions for photo-electrochemical water oxidation. We correlated this quantification to the electrochemical impedance spectroscopy (EIS) measurements, and showed that in anatase/rutile junction the increase in PEC performance was due to suppression in electron-hole recombination rate at the surface states that effectively enhances the hole transfer rate to the electrolyte. On the other hand, in rGO wrapped A-R MLNTs junction it was due to both phenomenon i.e decrease in bulk recombination rate as well as increase in hole transfer rate to the electrolyte at the semiconductor/electrolyte interface.

  10. Study on Au nanoparticles, TiO2 nanoclusters, and SiO2 nanoshells coated multi-wall carbon nanotubes/silica gel-glass

    NASA Astrophysics Data System (ADS)

    Zheng, Chan; Chen, Wenzhe; Ye, Xiaoyun

    2012-05-01

    Multi-wall carbon nanotubes (MWCNTs) coated with crystalline Au nanoparticles, TiO2 nanoclusters, and amorphous SiO2 nanoshells, to represent conductors, semiconductors, and insulators, respectively, were embedded in transparent silica gel-glass. The coated MWCNT/silica gel-glasses were prepared by the sol-gel technique. Scanning electron microscopy (SEM), X-ray diffraction (XRD), UV/Vis spectroscopy, Fourier Transform Infrared (FT-IR) spectroscopy and pore structure measurements were used to investigate the morphology, structure, and texture properties of the coated MWCNT/silica gel-glasses. The hardness and elastic modulus of the silica gel-glasses were characterized using a Nanoindenter and found to depend on the coating materials. Coating the MWCNTs with crystalline Au nanoparticles, TiO2 nanoclusters, and amorphous SiO2 nanoshells leads to an increase in the hardness and elastic modulus, despite the higher specific surface area and pore volume of the coated MWCNT/silica gel-glasses. Consequently, we can conclude that the mechanical properties of coated MWCNT/silica gel-glass might be greatly dependent on the guest MWCNTs rather than the silica gel matrix.

  11. Photo-reduced Cu/CuO nanoclusters on TiO2 nanotube arrays as highly efficient and reusable catalyst

    NASA Astrophysics Data System (ADS)

    Jin, Zhao; Liu, Chang; Qi, Kun; Cui, Xiaoqiang

    2017-01-01

    Non-noble metal nanoparticles are becoming more and more important in catalysis recently. Cu/CuO nanoclusters on highly ordered TiO2 nanotube arrays are successfully developed by a surfactant-free photoreduction method. This non-noble metal Cu/CuO-TiO2 catalyst exhibits excellent catalytic activity and stability for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with the presence of sodium borohydride (NaBH4). The rate constant of this low-cost Cu/CuO based catalyst is even higher than that of the noble metal nanoparticles decorated on the same TiO2 substrate. The conversion efficiency remains almost unchanged after 7 cycles of recycling. The recycle process of this Cu/CuO-TiO2 catalyst supported by Ti foil is very simple and convenient compared with that of the common powder catalysts. This catalyst also exhibited great catalytic activity to other organic dyes, such as methylene blue (MB), rhodamine B (RhB) and methyl orange (MO). This highly efficient, low-cost and easily reusable Cu/CuO-TiO2 catalyst is expected to be of great potential in catalysis in the future.

  12. Photodegradation of organic contamination in wastewaters by bonding TiO2/single-walled carbon nanotube composites with enhanced photocatalytic activity.

    PubMed

    Zhou, Wei; Pan, Kai; Qu, Yang; Sun, Fanfei; Tian, Chungui; Ren, Zhiyu; Tian, Guohui; Fu, Honggang

    2010-10-01

    Bonding TiO(2)/single-walled carbon nanotube (SWCNT) composites have been successfully synthesized through a facile sol-solvothermal technique. The obtained materials were characterized in detail by XRD, FT-IR, Raman and TEM. The results revealed that TiO(2) and SWNCT linked compactly through ester bonds and thus improved their interfaces. Therefore, the recombination of photogenerated electron-hole pairs was inhibited efficiently, which improved the photocatalytic activity. A reasonable mechanism was proposed to explain its formation. The photocatalytic activity was investigated utilizing rhodamine B and nitrobenzene (NB) as models for organic contamination in wastewaters. Experimental results indicated that this bonding composite exhibited higher photocatalytic activity than that of Degussa P25. The excellent photocatalytic activity could be attributed to larger surface area, smaller crystalline size, and especially the ester bonds, which was further confirmed by surface photovoltage spectroscopy. Furthermore, by adding ()OH scavenger tert-butanol, the obvious decrease of NB photodegradation indicated that NB was oxidized primarily by ()OH. The photodegradation products were identified by GC/MS, further indicating that the degradation proceeded via ()OH oxidation. A possible reaction pathway for the degradation of NB was suggested by the evidence presented in this study.

  13. Photocatalytic direct conversion of ethanol to 1,1- diethoxyethane over noble-metal-loaded TiO2 nanotubes and nanorods.

    PubMed

    Zhang, Hongxia; Wu, Yupeng; Li, Li; Zhu, Zhenping

    2015-04-13

    As one of the most important biomass platform molecules, ethanol needs to have its product chain chemically extended to meet future demands in renewable fuels and chemicals. Additionally, chemical conversion of ethanol under mild and green conditions is still a major challenge. In this work, ethanol is directly converted into 1,1-diethoxyethane (DEE) and H2 under mild photocatalytic conditions over platinum-loaded TiO2 nanotubes and nanorods. The reaction follows a tandem dehydrogenation-acetalization mechanism, in which ethanol is first dehydrogenated into acetaldehyde and H(+) ion by photogenerated holes, and then acetalization between acetaldehyde and ethanol proceeds through promotion by H(+) ions formed in real time. Excess H(+) ions are simultaneously reduced into H2 by photogenerated electrons. This photocatalytic process has a very high reaction rate over nanosized tubular and rod-like TiO2 photocatalysts, reaching 157.7 mmol g(-1)  h(-1) in relatively low photocatalyst feeding. More importantly, the reaction is highly selective, with a nearly stoichiometric conversion of reacted ethanol into DEE. This photocatalytic dehydrogenation CO coupling of ethanol is a new green approach to the direct efficient conversion of ethanol into DEE and provides a promising channel for sustainable bioethanol applications.

  14. Photo-reduced Cu/CuO nanoclusters on TiO2 nanotube arrays as highly efficient and reusable catalyst

    PubMed Central

    Jin, Zhao; Liu, Chang; Qi, Kun; Cui, Xiaoqiang

    2017-01-01

    Non-noble metal nanoparticles are becoming more and more important in catalysis recently. Cu/CuO nanoclusters on highly ordered TiO2 nanotube arrays are successfully developed by a surfactant-free photoreduction method. This non-noble metal Cu/CuO-TiO2 catalyst exhibits excellent catalytic activity and stability for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with the presence of sodium borohydride (NaBH4). The rate constant of this low-cost Cu/CuO based catalyst is even higher than that of the noble metal nanoparticles decorated on the same TiO2 substrate. The conversion efficiency remains almost unchanged after 7 cycles of recycling. The recycle process of this Cu/CuO-TiO2 catalyst supported by Ti foil is very simple and convenient compared with that of the common powder catalysts. This catalyst also exhibited great catalytic activity to other organic dyes, such as methylene blue (MB), rhodamine B (RhB) and methyl orange (MO). This highly efficient, low-cost and easily reusable Cu/CuO-TiO2 catalyst is expected to be of great potential in catalysis in the future. PMID:28071708

  15. Air-gating and chemical-gating in transistors and sensing devices made from hollow TiO2 semiconductor nanotubes.

    PubMed

    Alivov, Yahya; Funke, Hans; Nagpal, Prashant

    2015-07-24

    Rapid miniaturization of electronic devices down to the nanoscale, according to Moore's law, has led to some undesirable effects like high leakage current in transistors, which can offset additional benefits from scaling down. Development of three-dimensional transistors, by spatial extension in the third dimension, has allowed higher contact area with a gate electrode and better control over conductivity in the semiconductor channel. However, these devices do not utilize the large surface area and interfaces for new electronic functionality. Here, we demonstrate air gating and chemical gating in hollow semiconductor nanotube devices and highlight the potential for development of novel transistors that can be modulated using channel bias, gate voltage, chemical composition, and concentration. Using chemical gating, we reversibly altered the conductivity of nanoscaled semiconductor nanotubes (10-500 nm TiO2 nanotubes) by six orders of magnitude, with a tunable rectification factor (ON/OFF ratio) ranging from 1-10(6). While demonstrated air- and chemical-gating speeds were slow here (∼seconds) due to the mechanical-evacuation rate and size of our chamber, the small nanoscale volume of these hollow semiconductors can enable much higher switching speeds, limited by the rate of adsorption/desorption of molecules at semiconductor interfaces. These chemical-gating effects are completely reversible, additive between different chemical compositions, and can enable semiconductor nanoelectronic devices for 'chemical transistors', 'chemical diodes', and very high-efficiency sensing applications.

  16. Cu2O/Ag co-deposited TiO2 nanotube array film prepared by pulse-reversing voltage and photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Ding, Qi; Chen, Suiyuan; Shang, Fanmin; Liang, Jing; Liu, Changsheng

    2016-12-01

    In this experiment, Cu2O/Ag co-deposition TiO2 nanotube array (Cu2O-Ag-TNT) film was prepared on pure Ti substrate with the method of combining anodic oxidation and electrodeposition by pulse-reversing voltage power supply in the electrolyte of NH4F, ethylene glycol, CuNO3 · 3H2O and AgNO3. The morphology, phase, chemical composition, photocatalytic property and mechanism of the nanotube array film were studied by means of scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy, transmission electron microscopy, UV-vis diffuse reflectance spectra, photoluminescence and photocatalytic degradation under visible light. The results showed that the depositional Cu2O and Ag existed in two forms, being the small-particle dispersion and large-particle sedimentary phase in the nanotube arrays: Cu2O-Ag-TNTs for different doping amounts of Ag could be prepared by adjusting the concentration of AgNO3 and the reverse voltages; with changing of the doping amount of Ag, the band gap and photo-generated electron-hole pair recombination rate also changed, and under the conditions of annealing and the optimized process parameter, the band gap of the nanotube arrays narrowed 0.49 eV and the rate of electron and pair recombination decreased noticeably; the nanotube array film for the concentration of 0.5 cm2 ml-1 degraded the methylene blue of 8 mg L-1, and the degradation rate reached above 98%. The co-deposition Cu2O-Ag-TNT film prepared by the one-step method performed well in the field of photocatalysis under visible light.

  17. An in situ photoelectrochemical determination of hydrogen sulfide through generation of CdS nanoclusters onto TiO2 nanotubes.

    PubMed

    Li, Hong; Tian, Yang; Deng, Zifeng; Liang, Yan

    2012-10-07

    A novel and facile photoelectrochemical method has been developed to detect H(2)S in water samples with high sensitivity and selectivity. The protocol is based on the photocurrent generated by CdS nanoclusters which are deposited onto TiO(2) nanotubes exposing in CdSO(4) solution with the gradual addition of Na(2)S, with low-cost, environment-friendly, theoretical and technical simplicity. The developed method shows a very broad linear range from 10(-8) M to 10(-3) M and a low detection limit of 0.31 nM (9.92 ppt), far lower than the ceiling value in drinking water provided by WHO. Furthermore, the present method has been applied for determination of H(2)S in water samples. The concentrations of H(2)S in water samples determined by the present method are in a good agreement with those monitored by traditional spectrophotometry.

  18. Ag nanoparticle-filled TiO2 nanotube arrays prepared by anodization and electrophoretic deposition for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Wei, Xing; Sugri Nbelayim, Pascal; Kawamura, Go; Muto, Hiroyuki; Matsuda, Atsunori

    2017-03-01

    A layer of TiO2 nanotube (TNT) arrays with a thickness of 13 μm is synthesized by a two-step anodic oxidation from Ti metal foil. Surface charged Ag nanoparticles (NPs) are prepared by chemical reduction. After a pretreatment of the TNT arrays by acetone vapor, Ag NP filled TNT arrays can be achieved by electrophoretic deposition (EPD). Effects of the applied voltage during EPD such as DC–AC difference, frequency and waveform are investigated by quantitative analysis using atomic absorption spectroscopy. The results show that the best EPD condition is using DC 2 V + AC 4 V and a square wave of 1 Hz as the applied voltage. Back illuminated dye-sensitized solar cells are fabricated from TNT arrays with and without Ag NPs. The efficiency increased from 3.70% to 5.01% by the deposition of Ag NPs.

  19. Ag nanoparticle-filled TiO2 nanotube arrays prepared by anodization and electrophoretic deposition for dye-sensitized solar cells.

    PubMed

    Wei, Xing; Nbelayim, Pascal Sugri; Kawamura, Go; Muto, Hiroyuki; Matsuda, Atsunori

    2017-03-01

    A layer of TiO2 nanotube (TNT) arrays with a thickness of 13 μm is synthesized by a two-step anodic oxidation from Ti metal foil. Surface charged Ag nanoparticles (NPs) are prepared by chemical reduction. After a pretreatment of the TNT arrays by acetone vapor, Ag NP filled TNT arrays can be achieved by electrophoretic deposition (EPD). Effects of the applied voltage during EPD such as DC-AC difference, frequency and waveform are investigated by quantitative analysis using atomic absorption spectroscopy. The results show that the best EPD condition is using DC 2 V + AC 4 V and a square wave of 1 Hz as the applied voltage. Back illuminated dye-sensitized solar cells are fabricated from TNT arrays with and without Ag NPs. The efficiency increased from 3.70% to 5.01% by the deposition of Ag NPs.

  20. Sensitive determination of dopamine in the presence of uric acid and ascorbic acid using TiO2 nanotubes modified with Pd, Pt and Au nanoparticles.

    PubMed

    Mahshid, Sara; Li, Chengcheng; Mahshid, Sahar Sadat; Askari, Masoud; Dolati, Abolghasem; Yang, Lixia; Luo, Shenglian; Cai, Qingyun

    2011-06-07

    A simple modified TiO(2) nanotubes electrode was fabricated by electrodeposition of Pd, Pt and Au nanoparticles. The TiO(2) nanotubes electrode was prepared using the anodizing method, followed by modifying Pd nanoparticles onto the tubes surface, offering a uniform conductive surface for electrodeposition of Pt and Au. The performance of the modified electrode was characterized by cyclic voltammetry and differential pulse voltammetry methods. The Au/Pt/Pd/TiO(2) NTs modified electrode represented a high sensitivity towards individual detection of dopamine as well as simultaneous detection of dopamine and uric acid using 0.1 M phosphate buffer solution (pH 7.00) as the base solution. In both case, electro-oxidation peak currents of dopamine were linearly related to accumulated concentration over a wide concentration range of 5.0 × 10(-8) to 3.0 × 10(-5) M. However in the same range of dopamine concentration, the sensitivity had a significant loss at Pt/Pd/TiO(2) NTs electrode, suggesting the necessity for Au nanoparticles in modified electrode. The limit of the detection was determined as 3 × 10(-8) M for dopamine at signal-to-noise ratio equal to 3. Furthermore, the Au/Pt/Pd/TiO(2) NTs modified electrode was able to distinguish the oxidation response of dopamine, uric acid and ascorbic acid in mixture solution of different acidity. It was shown that the modified electrode possessed a very good reproducibility and long-term stability. The method was also successfully applied for determination of DA in human urine samples with satisfactory results.

  1. Enhancing the photocatalytic properties of TiO2 by coupling with carbon nanotubes and supporting gold.

    PubMed

    Wang, Huihu; Dong, Shijie; Chang, Ying; Faria, Joaquim L

    2012-10-15

    The photodegradation of methylene blue in aqueous solutions is studied using various photocatalysts, including neat TiO(2), CNT-TiO(2), Au-TiO(2), and Au-CNT-TiO(2) composites MB. Materials were synthesized and extensively characterized by XRD, TEM, DRFIT spectroscopy, N(2) adsorption-desorption isotherms, as well as diffuse reflectance UV-vis spectroscopy. By using CNT-TiO(2) composite as catalysts, it was found that CNT act as adsorbent and photosensitizer to improve the photoactivity of neat TiO(2). Among the CNT-TiO(2) composites with different CNT weight ratio (0.2-20%), the 2%CNT-TiO(2) shows the best photoactivity. When CNT content is larger than 2%, the surplus CNT may absorb and scatter light photons. Combined with the decrease of TiO(2) amount in composite, the photoactivity is reduced. To further improve the photoactivity of 2%CNT-TiO(2), different Au loads varying from 0.25% to 1% were introduced by the deposition-precipitation method. The 0.25%Au-2%CNT-TiO(2) composite had the highest photoactivity. The increase in activity was explained by the surface plasmon resonance of Au that makes the composite to absorb more photons than the 2%CNT-TiO(2), thus overcoming the disadvantages of surplus CNT addition. On the other hand, 0.25%Au-2%CNT-TiO(2) composite also presents higher activity than 0.25%Au-TiO(2) due to higher adsorption capacity provided by CNT introduction. The addition of CNT and Au simultaneously has a much stronger synergic role than when each of them is introduced individually.

  2. Incorporation of N-doped TiO2 nanorods in regenerated cellulose thin films fabricated from recycled newspaper as a green portable photocatalyst.

    PubMed

    Mohamed, Mohamad Azuwa; Salleh, W N W; Jaafar, Juhana; Ismail, A F; Abd Mutalib, Muhazri; Jamil, Siti Munira

    2015-11-20

    In this work, an environmental friendly RC/N-TiO2 nanocomposite thin film was designed as a green portable photocatalyst by utilizing recycled newspaper as sustainable cellulose resource. Investigations on the influence of N-doped TiO2 nanorods incorporation on the structural and morphological properties of RC/N-TiO2 nanocomposite thin film are presented. The resulting nanocomposite thin film was characterized by FESEM, AFM, FTIR, UV-vis-NIR spectroscopy, and XPS analysis. The results suggested that there was a remarkable compatibility between cellulose and N-doped TiO2 nanorods anchored onto the surface of the RC/N-TiO2 nanocomposite thin film. Under UV and visible irradiation, the RC/N-TiO2 nanocomposite thin film showed remarkable photocatalytic activity for the degradation of methylene blue solution with degradation percentage of 96% and 78.8%, respectively. It is crucial to note that the resulting portable photocatalyst produced via an environmental and green technique in its fabrication process has good potential in the field of water and wastewater treatment application.

  3. Nanostructural evolution of one-dimensional BaTiO3 structures by hydrothermal conversion of vertically aligned TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Muñoz-Tabares, J. A.; Bejtka, K.; Lamberti, A.; Garino, N.; Bianco, S.; Quaglio, M.; Pirri, C. F.; Chiodoni, A.

    2016-03-01

    The use of TiO2 nanotube (NT) arrays as templates for hydrothermal conversion of one-dimensional barium titanate (BaTiO3) structures is considered a promising synthesis approach, even though the formation mechanisms are not yet fully understood. Herein we report a nanostructural study by means of XRD and (HR)TEM of high aspect ratio TiO2-NTs hydrothermally converted into BaTiO3. The nanostructure shows two different and well-defined regions: at the top the conversion involves complete dissolution of NTs and subsequent precipitation of BaTiO3 crystals by homogeneous nucleation, followed by the growth of dendritic structures by aggregation and oriented attachment mechanisms. Instead, at the bottom, the low liquid/solid ratio, due to the limited amount of Ba solution that infiltrates the NTs, leads to the rapid crystallization of such a solution into BaTiO3, thus allowing the NTs to act as a template for the formation of highly oriented one-dimensional nanostructures. The in-depth analysis of the structural transformations that take place during the formation of the rod-like arrays of BaTiO3 could help elucidate the conversion mechanism, thus paving the way for the optimization of the synthesis process in view of new applications in energy harvesting devices, where easy and low temperature processing, controlled composition, morphology and functional properties are required.The use of TiO2 nanotube (NT) arrays as templates for hydrothermal conversion of one-dimensional barium titanate (BaTiO3) structures is considered a promising synthesis approach, even though the formation mechanisms are not yet fully understood. Herein we report a nanostructural study by means of XRD and (HR)TEM of high aspect ratio TiO2-NTs hydrothermally converted into BaTiO3. The nanostructure shows two different and well-defined regions: at the top the conversion involves complete dissolution of NTs and subsequent precipitation of BaTiO3 crystals by homogeneous nucleation, followed by the

  4. Recognition unit-free and self-cleaning photoelectrochemical sensing platform on TiO2 nanotube photonic crystals for sensitive and selective detection of dopamine release from mouse brain.

    PubMed

    Xin, Yanmei; Li, Zhenzhen; Wu, Wenlong; Fu, Baihe; Wu, Hongjun; Zhang, Zhonghai

    2017-01-15

    For implementing sensitive and selective detection of biological molecules, the biosensors are been designed more and more complicated. The exploration of detection platform in a simple way without loss their sensitivity and selectivity is always a big challenge. Herein, a prototype of recognition biomolecule unit-free photoelectrochemical (PEC) sensing platform with self-cleaning activity is proposed with TiO2 nanotube photonic crystal (TiO2 NTPCs) materials as photoelectrode, and dopamine (DA) molecule as both sensitizer and target analyte. The unique adsorption between DA and TiO2 NTPCs induces the formation of charge transfer complex, which not only expends the optical absorption of TiO2 into visible light region, thus significantly boosts the PEC performance under illumination of visible light, but also implements the selective detection of DA on TiO2 photoelectrode. This simple but efficient PEC analysis platform presents a low detection limit of 0.15nm for detection of DA, which allows to realize the sensitive and selective determination of DA release from the mouse brain for its practical application after coupled with a microdialysis probe. The DA functionalized TiO2 NTPCs PEC sensing platform opens up a new PEC detection model, without using extra-biomolecule auxiliary, just with target molecule naturally adsorbed on the electrode for sensitive and selective detection, and paves a new avenue for biosensors design with minimalism idea.

  5. Reconstruction of TiO2/MnO2-C nanotube/nanoflake core/shell arrays as high-performance supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Xiong, Qinqin; Zheng, Cun; Chi, Hongzhong; Zhang, Jun; Ji, Zhenguo

    2017-02-01

    Construction of electrodes with fast reaction kinetics is of great importance for achieving advanced supercapacitors. Herein we report a facile combined synthetic strategy with atomic layer deposition (ALD) and electrodeposition to rationally fabricate nanotube/nanoflake core/shell arrays. ALD-TiO2 nanotubes are used as the skeleton core for assembly of electrodeposited MnO2-C nanoflake shells forming a core/shell structure. Highly porous architecture and good electrical conductivity are combined in this unique core/shell structure, resulting in fast ion/electron transfer. In tests of electrochemical performance, the TiO2/MnO2-C core/shell arrays are characterized as cathode for asymmetric supecapacitors and exhibit high specific capacitance (880 F g-1 at 2.5 A g-1), excellent rate properties (735 F g-1 at 30 A g-1) and good long-term cycling stability (94.3% capacitance retention after 20 000 cycles). The proposed electrode construction strategy is favorable for fabrication of other advanced supercapacitor electrodes.

  6. TiO2 Nanotube-Carbon (TNT-C) as Support for Pt-based Catalyst for High Methanol Oxidation Reaction in Direct Methanol Fuel Cell.

    PubMed

    Abdullah, M; Kamarudin, S K; Shyuan, L K

    2016-12-01

    In this study, TiO2 nanotubes (TNTs) were synthesized via a hydrothermal method using highly concentrated NaOH solutions varying from 6 to 12 M at 180 °C for 48 h. The effects of the NaOH concentration and the TNT crystal structure on the performance for methanol oxidation were investigated to determine the best catalyst support for Pt-based catalysts. The results showed that TNTs produced with 10 M NaOH exhibited a length and a diameter of 550 and 70 nm, respectively; these TNTs showed the best nanotube structure and were further used as catalyst supports for a Pt-based catalyst in a direct methanol fuel cell. The synthesized TNT and Pt-based catalysts were analysed by FESEM, TEM, BET, EDX, XRD and FTIR. The electrochemical performance of the catalysts was investigated using cyclic voltammetry (CV) and chronoamperometric (CA) analysis to further understand the methanol oxidation in the direct methanol fuel cell (DMFC). Finally, the result proves that Pt-Ru/TNT-C catalyst shows high performance in methanol oxidation as the highest current density achieved at 3.3 mA/cm(2) (normalised by electrochemically active surface area) and high catalyst tolerance towards poisoning species was established.

  7. Investigation of the feasibility of TiO(2) nanotubes for the enrichment of DDT and its metabolites at trace levels in environmental water samples.

    PubMed

    Zhou, Qingxiang; Ding, Yujie; Xiao, Junping; Liu, Guoguang; Guo, Xiaoyang

    2007-04-13

    TiO(2) nanotubes, novel nanomaterials synthesized from hydrothermal treatment, were investigated for being used as a new solid-phase extraction adsorbent with o,p'-DDT, [1,1,1-trichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl)ethane, p,p'-DDT, [1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane] and its principle metabolites p,p'-DDD, [1,1-dichloro-2,2-bis(4-chlorophenyl)ethane] and p,p'-DDE [1,1-(2,2-dichloro-ethanylidene)-bis(4-chlorobenzene)] as the target analytes. Several factors such as eluant and its volume, the sample pH, sample volume and the flow rate of samples, were optimized. The effect of humic acid, which is often present in natural water system, was also investigated. Under the optimal conditions, lower detection limits of 0.0031, 0.0037, 0.0053 and 0.0025 ng mL(-1) for p,p'-DDD, p,p'-DDT, o,p'-DDT and p,p'-DDE, respectively, were obtained. The proposed method was successfully applied to the analysis of the target compounds in several environmental water samples. Good recoveries over the range of 81.2-115% were obtained. These results indicated that titanium nanotubes had enormous potential in environmental field as a novel SPE adsorbent material.

  8. TiO2 Nanotube-Carbon (TNT-C) as Support for Pt-based Catalyst for High Methanol Oxidation Reaction in Direct Methanol Fuel Cell

    NASA Astrophysics Data System (ADS)

    Abdullah, M.; Kamarudin, S. K.; Shyuan, L. K.

    2016-12-01

    In this study, TiO2 nanotubes (TNTs) were synthesized via a hydrothermal method using highly concentrated NaOH solutions varying from 6 to 12 M at 180 °C for 48 h. The effects of the NaOH concentration and the TNT crystal structure on the performance for methanol oxidation were investigated to determine the best catalyst support for Pt-based catalysts. The results showed that TNTs produced with 10 M NaOH exhibited a length and a diameter of 550 and 70 nm, respectively; these TNTs showed the best nanotube structure and were further used as catalyst supports for a Pt-based catalyst in a direct methanol fuel cell. The synthesized TNT and Pt-based catalysts were analysed by FESEM, TEM, BET, EDX, XRD and FTIR. The electrochemical performance of the catalysts was investigated using cyclic voltammetry (CV) and chronoamperometric (CA) analysis to further understand the methanol oxidation in the direct methanol fuel cell (DMFC). Finally, the result proves that Pt-Ru/TNT-C catalyst shows high performance in methanol oxidation as the highest current density achieved at 3.3 mA/cm2 (normalised by electrochemically active surface area) and high catalyst tolerance towards poisoning species was established.

  9. Reconstruction of TiO2/MnO2-C nanotube/nanoflake core/shell arrays as high-performance supercapacitor electrodes.

    PubMed

    Xiong, Qinqin; Zheng, Cun; Chi, Hongzhong; Zhang, Jun; Ji, Zhenguo

    2017-02-03

    Construction of electrodes with fast reaction kinetics is of great importance for achieving advanced supercapacitors. Herein we report a facile combined synthetic strategy with atomic layer deposition (ALD) and electrodeposition to rationally fabricate nanotube/nanoflake core/shell arrays. ALD-TiO2 nanotubes are used as the skeleton core for assembly of electrodeposited MnO2-C nanoflake shells forming a core/shell structure. Highly porous architecture and good electrical conductivity are combined in this unique core/shell structure, resulting in fast ion/electron transfer. In tests of electrochemical performance, the TiO2/MnO2-C core/shell arrays are characterized as cathode for asymmetric supecapacitors and exhibit high specific capacitance (880 F g(-1) at 2.5 A g(-1)), excellent rate properties (735 F g(-1) at 30 A g(-1)) and good long-term cycling stability (94.3% capacitance retention after 20 000 cycles). The proposed electrode construction strategy is favorable for fabrication of other advanced supercapacitor electrodes.

  10. Photoelectrocatalytic reduction of CO2 into chemicals using Pt-modified reduced graphene oxide combined with Pt-modified TiO2 nanotubes.

    PubMed

    Cheng, Jun; Zhang, Meng; Wu, Gai; Wang, Xin; Zhou, Junhu; Cen, Kefa

    2014-06-17

    The photoelectrocatalytic (PEC) reduction of CO2 into high-value chemicals is beneficial in alleviating global warming and advancing a low-carbon economy. In this work, Pt-modified reduced graphene oxide (Pt-RGO) and Pt-modified TiO2 nanotubes (Pt-TNT) were combined as cathode and photoanode catalysts, respectively, to form a PEC reactor for converting CO2 into valuable chemicals. XRD, XPS, TEM, AFM, and SEM were employed to characterize the microstructures of the Pt-RGO and Pt-TNT catalysts. Reduction products, such as C2H5OH and CH3COOH, were obtained from CO2 under band gap illumination and biased voltage. A combined liquid product generation rate (CH3OH, C2H5OH, HCOOH, and CH3COOH) of approximately 600 nmol/(h·cm(2)) was observed. Carbon atom conversion rate reached 1,130 nmol/(h·cm(2)), which were much higher than those achieved using Pt-modified carbon nanotubes and platinum carbon as cathode catalysts.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    TiO2 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 Agcore-Cushell 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.

  12. Fabrication of TiO2 nanotubes on porous titanium scaffold and biocompatibility evaluation in vitro and in vivo.

    PubMed

    Fan, Xingping; Feng, Bo; Liu, Zhiyuan; Tan, Jing; Zhi, Wei; Lu, Xiong; Wang, Jianxin; Weng, Jie

    2012-12-01

    Porous titanium was modified by anodic oxidation and heat treatment method. Scanning electron microscopy and X-ray diffraction examinations revealed that the modified surface of porous titanium was covered by anatase nanotubes. In vitro, the bioactivity of specimens before and after modification was evaluated by immersing into the double-concentration simulated body fluid for 7 days. The porous titanium specimens were implanted into the femurs of dogs for 3 months. The osteointegration of the implants was investigated by push-out test and histological examination. The results showed that the porous titanium with anatase nanotubes has the superior ability of apatite formation and a higher push-out force when compared with the other implants. The histological analysis indicated that the implant with anatase nanotubes had excellent ability to facilitate the osteointegration in vivo.

  13. Uniformly dispersed and controllable ligand-free silver-nanoparticle-decorated TiO2 nanotube arrays with enhanced photoelectrochemical behaviors.

    PubMed

    Bian, Haidong; Shu, Xia; Zhang, Jianfang; Yuan, Bao; Wang, Yan; Liu, Lingjuan; Xu, Guangqing; Chen, Zhong; Wu, Yucheng

    2013-11-01

    Homogeneously dispersed silver nanoparticles (AgNPs) were successfully decorated onto the surface of TiO2 nanotube arrays (TNTA) by means of an in situ photoreduction method. TNTA films as supports exhibit excellent properties to prevent agglomeration of AgNPs, and they also avoid using polymer ligands, which is deleterious to enhancing the properties of the fabricated NPs. The silver particle size and its content could be controlled just by changing the immersion time. Detailed SEM and TEM analyses combined with energy-dispersive X-ray spectroscopy analyses with different immersion times (5, 10, 30, 60 min) have revealed the variation tendency. The prepared Ag/TNTA composite films were also characterized by XRD, X-ray photoelectron spectroscopy, and high-resolution TEM. The UV/Vis diffuse reflectance spectra displayed a redshift of the absorption peak with the growth of AgNPs. The photocurrent response and the photoelectrocatalytic degradation of methyl orange (MO) were used to evaluate the photoelectrochemical properties of the fabricated samples. The results showed that the photocurrent response and photoelectrocatalytic activity largely depended on the loaded Ag particle size and content. TNTA films with a diameter of 17.92 nm and silver content of 1.15 at% showed the highest photocurrent response and degradation rate of MO. The enhanced properties could be attributed to the synergistic effect between AgNPs and TiO2. To make good use of this effect, particle size and silver content should be well controlled to develop the electron charge and discharge process during the photoelectrical process. Neither smaller nor larger AgNPs caused decreased photoelectrical properties.

  14. Ultra-sensitive determination of epinephrine based on TiO2-Au nanoclusters supported on reduced graphene oxide and carbon nanotube hybrid nanocomposites.

    PubMed

    Li, Jianbo; Wang, Xiaojiao; Duan, Huimin; Wang, Yanhui; Luo, Chuannan

    2016-07-01

    A highly efficient and sensitive electrochemical sensor for EP based on reduced graphene and multi-walled carbon nanotube hybrid nanocomposites loaded TiO2-Au nano-clusters modified glassy carbon electrode was developed. The surface nature and morphology of the nanocomposite film and the electrochemical properties of the sensor were characterized by Raman spectra, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectra (EDX), Fourier transform infrared spectroscopy (FT-IR), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), respectively. Carbon nanomaterials were widely used in sensing due to its large electroactive surface area, fast electron transport and strong adsorption capacity. Meanwhile, TiO2-Au nano-clusters could accelerate the electron transfer, increase reactive site and extend electrochemical response window. The nanocomposite film could greatly enhance the response sensitivity and decrease the overpotential. The resulting sensor showed an excellent electrocatalytic activity toward EP. Under the optimum conditions (i.e. pH6.0, 0.1M PBS, preconcentration for 110s), Differential pulse voltammetry was employed to detect ultra-trace amounts of EP. The result of a wide linear range of 1.0-300nM and limited of detection 0.34nM (S/N=3) were obtained. The constructed sensor exhibited excellent accuracy and precision, the relative standard deviation (RSD) was less than 5%. The nanocomposite film sensor was successfully used to accurately detect the content of EP in practical samples, and the recoveries for the standards added are 97%-105%.

  15. High performance PbS quantum dot sensitized solar cells via electric field assisted in situ chemical deposition on modulated TiO2 nanotube arrays.

    PubMed

    Tao, Liang; Xiong, Yan; Liu, Hong; Shen, Wenzhong

    2014-01-21

    Quantum dot sensitized solar cells (QDSSCs) are attractive photovoltaic devices due to their simplicity and low material requirements. However, efforts to realize high efficiencies in QDSSCs have often been offset by complicated processes and expensive or toxic materials, significantly limiting their useful application. In this work, we have realized for the first time, high performance PbS QDSSCs based on TiO2 nanotube arrays (NTAs) via an in situ chemical deposition method controlled by a low electric field. An efficiency, η, of ~3.41% under full sun illumination has been achieved, which is 133.6% higher than the best result previously reported for a simple system without doping or co-sensitizing, and comparable to systems with additional chemicals. Furthermore, a high open-circuit voltage (0.64 V), short-circuit current (8.48 mA cm(-2)) and fill factor (0.63) have been achieved. A great increase in the quantity of the loaded quantum dots (QDs) in the NTAs was obtained from the in situ electric field assisted chemical bath deposition (EACBD) process, which was the most significant contributing factor with respect to the high JSC. The high VOC and FF have been attributed to a much shorter electron path, less structural and electronic defects, and lower recombination in the ordered TiO2 NTAs produced by oscillating anodic voltage. Besides, the optimal film thickness (~4 μm) based on the NTAs was much thinner than that of the control cell based on nanoporous film (~30.0 μm). This investigation can hopefully offer an effective way of realizing high performance QDSSCs and QD growth/installation in other nanostructures as well.

  16. Attenuation of the macrophage inflammatory activity by TiO2 nanotubes via inhibition of MAPK and NF-κB pathways

    PubMed Central

    Neacsu, Patricia; Mazare, Anca; Schmuki, Patrik; Cimpean, Anisoara

    2015-01-01

    Biomaterial implantation in a living tissue triggers the activation of macrophages in inflammatory events, promoting the transcription of pro-inflammatory mediator genes. The initiation of macrophage inflammatory processes is mainly regulated by signaling proteins of mitogen-activated protein kinase (MAPK) and by nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways. We have previously shown that titania nanotubes modified Ti surfaces (Ti/TiO2) mitigate the immune response, compared with flat Ti surfaces; however, little is known regarding the underlying mechanism. Therefore, the aim of this study is to investigate the mechanism(s) by which this nanotopography attenuates the inflammatory activity of macrophages. Thus, we analyzed the effects of TiO2 nanotubes on the activation of MAPK and NF-κB signaling pathways in standard and lipopolysaccharide-evoked conditions. Results showed that the Ti/TiO2 significantly reduce the expression levels of the phosphorylated forms of p38, ERK1/2, c-Jun NH2-terminal kinase (JNK), IKKβ, and IkB-α. Furthermore, a significant reduction in the p65 nuclear accumulation on the nanotubular surface was remarked. Following, by using specific MAPK inhibitors, we observed that lipopolysaccharide-induced production of monocyte chemotactic protein-1 and nitric oxide was significantly inhibited on the Ti/TiO2 surface via p38 and ERK1/2, but not via JNK. However, the selective inhibitor for JNK signaling pathway (SP600125) was effective in reducing tumor necrosis factor alpha release as well as monocyte chemotactic protein-1 and nitric oxide production. Altogether, these data suggest that titania nanotubes can attenuate the macrophage inflammatory response via suppression of MAPK and NF-κB pathways providing a potential mechanism for their anti-inflammatory activity. PMID:26491301

  17. In situ synthesis of carbon incorporated TiO2 with long-term performance as anode for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Chen, Yang; Ma, Xiaoqing; Cui, Xiaoli; Jiang, Zhiyu

    2016-01-01

    The carbon incorporated titanium dioxide (C-TiO2) has been in-situ synthesized via facile flame-assisted approach using tetrabutyl orthotitanate as a precursor. The as-prepared C-TiO2 samples are characterized by SEM, XRD, XPS, Raman spectroscopy, EDX, TGA and electrochemical measurements. It is found that carbon incorporated TiO2 microspheres can be directly obtained without any post annealing. Enhanced lithium storage performance is observed for the resultant sample after ball milling. The reversible capacity remains 159.8 mAh g-1 at a specific current of 335 mA g-1 even after 960 charge-discharge cycles. The high capacity reversibility and good long-term cycling capability are attributed to the inherently incorporated carbon species, which efficiently improve electronic conductivity. Meanwhile, the intrinsic crystal structure and enlarged contact area between electrode and electrolyte provide abundant channels for Li-ion transport. This work could not only make the prepared C-TiO2 a promising anode candidate, but also present an available strategy for developing other electrode materials.

  18. Signal-amplified platform for electrochemical immunosensor based on TiO2 nanotube arrays using a HRP tagged antibody-Au nanoparticles as probe.

    PubMed

    Gao, Zhi-Da; Guan, Fang-Fang; Li, Cheng-Yong; Liu, Hai-Feng; Song, Yan-Yan

    2013-03-15

    In this study, a novel signal-amplified electrochemical immunosensor was proposed by using TiO(2) nanotube (TiNT) arrays as the platform. Due to the distinct tubular features-large surface area, high pore volume and good electrochemical conductivity, the TiNT based electrodes exhibited excellent signal-amplified effects. gold nanoparticle (AuNP) was further utilized to bind horseradish peroxidase (HRP) tagged antibodies as recognition elements. Compared to the immunosensor based on either flat electrode, the immunosensors using TiNT layer as electrode showed higher amplified electrochemical signals from the catalytic reaction of HRP relative to hydrogen peroxide (H(2)O(2)). Under optimal conditions, the proposed immunosensor exhibited a good electrochemical behavior to antigen in a concentration range from 0.1 ng mL(-1) to 10(5) ng mL(-1) with a detection limit of 0.01 ng mL(-1). The results showed that the TiNT-based electrochemical immunosensing platform could provide a great potential in clinical application for detection of low-abundant proteins.

  19. Morphology dependent adsorption of methylene blue on trititanate nanoplates and nanotubes prepared by the hydrothermal treatment of TiO2.

    PubMed

    Dawson, Graham; Chen, Wei; Lu, Luhua; Dai, Kai

    2017-01-01

    The adsorption properties of two nanomorphologies of trititanate, nanotubes (TiNT) and plates (TiNP), prepared by the hydrothermal reaction of concentrated NaOH with different phases of TiO2, were examined. It was found that the capacity for both morphologies towards methylene blue (MB), an ideal pollutant, was extremely high, with the TiNP having a capacity of 130 mg/g, higher than the TiNT, whose capacity was 120 mg/g at 10 mg/L MB concentration. At capacity, the well-dispersed powders deposit on the floor of the reaction vessel. The two morphologies had very different structural and adsorption properties. TiNT with high surface area and pore volume exhibited exothermic monolayer adsorption of MB. TiNP with low surface area and pore volume yielded a higher adsorption capacity through endothermic multilayer adsorption governed by pore diffusion. TiNP exhibited a higher negative surface charge of -23 mV, compared to -12 mV for TiNT. The adsorption process appears to be an electrostatic interaction, with the cationic dye attracted more strongly to the nanoplates, resulting in a higher adsorption capacity and different adsorption modes. We believe this simple, low cost production of high capacity nanostructured adsorbent material has potential uses in wastewater treatment.

  20. Decoration of TiO2 nanotube arrays by graphitic-C3N4 quantum dots with improved photoelectrocatalytic performance

    NASA Astrophysics Data System (ADS)

    Sun, Bo; Lu, Na; Su, Yan; Yu, Hongtao; Meng, Xiangyu; Gao, Zhanming

    2017-02-01

    In this paper, we present a novel method to improve the photoelectrocatalytic (PEC) property of TiO2 nanotube arrays (TNTAs) by way of decorating it with visible-light-respond graphitic-C3N4 quantum dots (g-C3N4 QDs). The g-C3N4 QDs/TNTAs heterojunction is successfully prepared using a facile dipping method. The optimal condition of preparing g-C3N4 QDs/TNTAs heterojunction is found as 60 min of dipping duration and 0.2 mg mL-1 of g-C3N4 QDs dipping solution. The fabricated g-C3N4 QDs/TNTAs heterojunction shows improved PEC activity comparing to TNTAs due to its better separation capability of photo-generated charges and wider optical absorption. And the photocurrent generated by the optimal g-C3N4 QDs/TNTAs photoanode is 4.3 times than that of pristine TNTAs. Besides, the g-C3N4 QDs/TNTAs heterojunction also exhibits superior PEC activities in degradation of phenol. 98.6% of phenol is successfully degraded in 120 min and the pseudo-first-order kinetic constant of phenol degradation is 4.9 times as great as that of pristine TNTAs. This work indicates that the g-C3N4 QDs/TNTAs heterojunction is expected to be a promising nanomaterial for pollutant degradation and further application in solar energy conversion.

  1. Visible to near-infrared light harvesting in TiO2 nanotube array-P3HT based heterojunction solar cells.

    PubMed

    Mor, Gopal K; Kim, Sanghoon; Paulose, Maggie; Varghese, Oomman K; Shankar, Karthik; Basham, James; Grimes, Craig A

    2009-12-01

    The development of high-efficiency solid-state excitonic photovoltaic solar cells compatible with solution processing techniques is a research area of intense interest, with the poor optical harvesting in the red and near-IR (NIR) portion of the solar spectrum a significant limitation to device performance. Herein we present a solid-state solar cell design, consisting of TiO(2) nanotube arrays vertically oriented from the FTO-coated glass substrate, sensitized with unsymmetrical squaraine dye (SQ-1) that absorbs in the red and NIR portion of solar spectrum, and which are uniformly infiltrated with p-type regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT) that absorbs higher energy photons. Our solid-state solar cells exhibit broad, near-UV to NIR, spectral response with external quantum yields of up to 65%. Under UV filtered AM 1.5G of 90 mW/cm(2) intensity we achieve typical device photoconversion efficiencies of 3.2%, with champion device efficiencies of 3.8%.

  2. Effects of dominant material properties on the stability and transport of TiO2 nanoparticles and carbon nanotubes in aquatic environments: from synthesis to fate.

    PubMed

    Liu, Xuyang; Chen, Gexin; Keller, Arturo A; Su, Chunming

    2013-01-01

    Recently, increasing studies have focused on the environmental stability, transport, and fate of the anthropogenic nanomaterials in the environment, which contributes to the understanding of the potential risks when released. However, applying nanomaterials from different manufacturers and production methods tends to result in inconsistent experimental data and potentially a biased comparison. The aim of this review is to investigate the dominant material properties that determine the aggregation and deposition behavior of nanomaterials. Herein, we focus on two of the most popular anthropogenic nanomaterials, i.e., titanium dioxide (TiO2) and carbon nanotubes (CNTs). We start from the production methods of nanomaterials of different sources, and then examine their influence on the material properties and surface characteristics. The role of the material properties was carefully analyzed and correlated with the stability and transport in aquatic environments. These two case studies may be extended to other nanomaterials with similar surface properties, which will improve our understanding of the impact and risks of anthropogenic nanomaterials in the environment. This study highlights opportunities to design and produce "green" nanomaterials with less environmental risk and no sacrificing of the novel "nano" properties.

  3. Preparation, characterization and visible-light-driven photocatalytic activity of a novel Fe(III) porphyrin-sensitized TiO2 nanotube photocatalyst

    NASA Astrophysics Data System (ADS)

    Wei, Meng; Wan, Junmin; Hu, Zhiwen; Peng, Zhiqin; Wang, Bing; Wang, Huigang

    2017-01-01

    Iron(III) meso-tetra(4-carboxyphenyl) porphyrin (FeTCPP) loaded on the surface of TiO2 nanotubes (TNTs) has been successfully prepared through improved hydrothermal and heating reflux process. The new photocatalyst has been characterized and analyzed by TEM/EDS, BET, XRD, FT-IR, DRS, PL, XPS and EPR. The photocatalytic activity of FeTCPP/TNT nanocomposite was evaluated by the photodegradation of MB under visible light irradiation. The degradation results showed a purification of more than 90% MB in simulating wastewater, and confirmed that the prepared FeTCPP/TNT nanocomposite has acquired superior photocatalytic activitiy. The 6 times cycled results suggested the great stability of the photocatalyst. These results confirmed the FeTCPP played an important role in capturing photons and expanding the absorption wavelength to the visible light region, and the FeTCPP/TNT photocatalyst is also beneficial for the electron transfer and long-distance transmission, and could efficiently increase the separation of the electron-hole pairs, and accelerate the decomposition of organic pollutants. In addition, nano-sized structures can increase adsorption capability.

  4. Carbon-dot-decorated TiO2 nanotube arrays used for photo/voltage-induced organic pollutant degradation and the inactivation of bacteria

    NASA Astrophysics Data System (ADS)

    Feng, Lingyan; Sun, Hanjun; Ren, Jinsong; Qu, Xiaogang

    2016-03-01

    Photoluminescent carbon dots (c-dots) have recently attracted growing interest as a new member of the carbon-nanomaterial family. Here, we report for the first time that c-dot-decorated TiO2 nanotube arrays (c-dot/TiNTs) exhibit highly enhanced abilities regarding photo/voltage-induced organic pollutant degradation and bacterial inactivation. By applying UV irradiation (365 nm) or an electrochemical potential over 3 V (versus Ag/AgCl), an organic dye and a herbicide were efficiently degraded. Moreover, the inactivation of Gram-positive S. aureus and Gram-negative E. coli bacteria was realized on a c-dot/TiNT film. The c-dots were able to absorb light efficiently resulting in multiple exciton generation and also a reduction in the recombination of the e-/h+ pair produced in c-dot/TiNT film during photo/voltage-induced degradation. It was also possible to readily regenerate the surface using ultraviolet light irradiation, leaving the whole film structure undamaged and with high reproducibility and stability.

  5. A facile one-step synthesis of Mn3O4 nanoparticles-decorated TiO2 nanotube arrays as high performance electrode for supercapacitors

    NASA Astrophysics Data System (ADS)

    Zhang, Jianfang; Wang, Yan; Qin, Yongqiang; Yu, Cuiping; Cui, Lihua; Shu, Xia; Cui, Jiewu; Zheng, Hongmei; Zhang, Yong; Wu, Yucheng

    2017-02-01

    Via a facile one-step chemical bath deposition route, homogeneously dispersed Mn3O4 nanoparticles have been successfully deposited onto the inner surface of TiO2 nanotube arrays (TNAs). The content and size of Mn3O4 can be controlled by changing the deposition time. Field emission scanning electron microscopy and transmission electron microscopy analysis reveal the morphologies structures of Mn3O4/TNAs composites. The crystal-line structures are characterized by the X-ray diffraction patterns and Raman spectra. X-ray photoelectron spectroscopy further confirms the valence states of the sample elements. The electrochemical properties of Mn3O4/TNAs electrodes are systematically investigated by the combine use of cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The resulting Mn3O4/TNAs electrode prepared by deposition time of 3 h shows the highest specific capacitance of 570 F g-1 at a current density of 1 A g-1. And it also shows an excellent long-term cycling stability at a current density of 5 A g-1, which remaining 91.8% of the initial capacitance after 2000 cycles. Thus this kind of Mn3O4 nanoparticles decorated TNAs may be considered as an alternative promising candidate for high performance supercapacitor electrodes.

  6. Double-Sided Transparent TiO2 Nanotube/ITO Electrodes for Efficient CdS/CuInS2 Quantum Dot-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Chen, Chong; Ling, Lanyu; Li, Fumin

    2017-01-01

    In this paper, to improve the power conversion efficiencies (PCEs) of quantum dot-sensitized solar cells (QDSSCs) based on CdS-sensitized TiO2 nanotube (TNT) electrodes, two methods are employed on the basis of our previous work. First, by replacing the traditional single-sided working electrodes, double-sided transparent TNT/ITO (DTTO) electrodes are prepared to increase the loading amount of quantum dots (QDs) on the working electrodes. Second, to increase the light absorption of the CdS-sensitized DTTO electrodes and improve the efficiency of charge separation in CdS-sensitized QDSSCs, copper indium disulfide (CuInS2) is selected to cosensitize the DTTO electrodes with CdS, which has a complementary property of light absorption with CdS. The PCEs of QDSSCs based on these prepared QD-sensitized DTTO electrodes are measured. Our experimental results show that compared to those based on the CdS/DTTO electrodes without CuInS2, the PCEs of the QDSSCs based on CdS/CuInS2-sensitized DTTO electrode are significantly improved, which is mainly attributed to the increased light absorption and reduced charge recombination. Under simulated one-sun illumination, the best PCE of 1.42% is achieved for the QDSSCs based on CdS(10)/CuInS2/DTTO electrode, which is much higher than that (0.56%) of the QDSSCs based on CdS(10)/DTTO electrode.

  7. Double-Sided Transparent TiO2 Nanotube/ITO Electrodes for Efficient CdS/CuInS2 Quantum Dot-Sensitized Solar Cells.

    PubMed

    Chen, Chong; Ling, Lanyu; Li, Fumin

    2017-12-01

    In this paper, to improve the power conversion efficiencies (PCEs) of quantum dot-sensitized solar cells (QDSSCs) based on CdS-sensitized TiO2 nanotube (TNT) electrodes, two methods are employed on the basis of our previous work. First, by replacing the traditional single-sided working electrodes, double-sided transparent TNT/ITO (DTTO) electrodes are prepared to increase the loading amount of quantum dots (QDs) on the working electrodes. Second, to increase the light absorption of the CdS-sensitized DTTO electrodes and improve the efficiency of charge separation in CdS-sensitized QDSSCs, copper indium disulfide (CuInS2) is selected to cosensitize the DTTO electrodes with CdS, which has a complementary property of light absorption with CdS. The PCEs of QDSSCs based on these prepared QD-sensitized DTTO electrodes are measured. Our experimental results show that compared to those based on the CdS/DTTO electrodes without CuInS2, the PCEs of the QDSSCs based on CdS/CuInS2-sensitized DTTO electrode are significantly improved, which is mainly attributed to the increased light absorption and reduced charge recombination. Under simulated one-sun illumination, the best PCE of 1.42% is achieved for the QDSSCs based on CdS(10)/CuInS2/DTTO electrode, which is much higher than that (0.56%) of the QDSSCs based on CdS(10)/DTTO electrode.

  8. In situ fabrication of Ag3PO4/TiO2 nanotube heterojunctions with enhanced visible-light photocatalytic activity.

    PubMed

    Tong, Zhen Wei; Yang, Dong; Sun, Yuan Yuan; Tian, Yao; Jiang, Zhong Yi

    2015-05-14

    Ag3PO4/TiO2 nanotube (TNT) heterojunctions were fabricated via a facile in situ growth method. Hemispherical Ag3PO4 nanocrystals were uniformly grown on the TNT surface, and their size was confined to 5-10 nm. A joint area was distinctly observed between the Ag3PO4 nanocrystals and TNT, indicating the formation of a Ag3PO4/TNT heterojunction. Compared with pure Ag3PO4, the Ag3PO4/TNT heterojunction possesses more active sites, less bulk defects, more efficient electron-hole separation, as well as better dye adsorption properties, and thus exhibits a significantly elevated photocatalytic activity for Rhodamine B (RhB) degradation. The study of the reactive species demonstrates that the photocatalytic degradation of RhB over the Ag3PO4/TNT heterojunction is primarily driven by both photogenerated h(+) and ˙OH radicals. This easily-fabricated Ag3PO4/TNT heterojunction with promising photocatalytic activity may find potential applications in energy and environmental related areas.

  9. Nanocrystal Cu2O-loaded TiO2 nanotube array films as high-performance visible-light bactericidal photocatalyst.

    PubMed

    Zhang, Shengsen; Liu, Chang; Liu, Xiaolu; Zhang, Haimin; Liu, Porun; Zhang, Shanqing; Peng, Feng; Zhao, Huijun

    2012-12-01

    In this work, we report the use of a non-toxic nanocrystal Cu(2)O-loaded TiO(2) nanotube array (Cu(2)O/TNTs) film as high-performance visible-light bactericidal photocatalyst. The samples were characterized by field-emission scanning electron microscopy, X-ray photoelectron spectroscopy, and ultraviolet-visible diffusion reflection spectroscopy. This Cu(2)O/TNTs film photocatalyst is capable of complete inactivation of Escherichia coli in 5 × 10(7) colony-forming units/mL within a record short disinfection time of 20 min under visible-light irradiation. The average bactericidal percentage of the Cu(2)O/TNTs for E. coli under visible-light irradiation are 20 times and 6.6 times higher than those of TNTs under the same conditions and Cu(2)O/TNTs without light, respectively. This superior bactericidal performance is mainly attributed to the high ability to produce OH radicals by both photogenerated electron and hole of the prepared photocatalyst under visible light. The Cu(2)O/TNTs film photocatalyst makes it applicable to broad fields including drinking water disinfection.

  10. Enhanced performance of dye-sensitized solar cells based on organic dopant incorporated PVDF-HFP/PEO polymer blend electrolyte with g-C3N4/TiO2 photoanode

    NASA Astrophysics Data System (ADS)

    Senthil, R. A.; Theerthagiri, J.; Madhavan, J.; Murugan, K.; Arunachalam, Prabhakarn; Arof, A. K.

    2016-10-01

    This work describes the effect of 2-aminopyrimidine (2-APY) on poly(vinylidinefluoride-co-hexafluoropropylene) (PVDF-HFP)/polyethylene oxide (PEO) blend polymer electrolyte along with binary iodide salts (tetrabutylammonium iodide (TBAI) and potassium iodide (KI)) and iodine (I2) were studied for enhancing the efficiency of the dye-sensitized solar cells (DSSCs) consisting of g-C3N4/TiO2 composite as photoanode. The g-C3N4 was synthesized from low cost urea by thermal condensation method. It was used as a precursor to synthesize the various weight percentage ratios (5%, 10% and 15%) of g-C3N4/TiO2 composites by wet-impregnation method. The pure and 2-APY incorporated PVDF-HFP/PEO polymer blend electrolytes were arranged by wet chemical process (casting method) using DMF as a solvent. The synthesized g-C3N4/TiO2 composites and polymer blend electrolytes were studied and analyzed by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The ionic conductivity values of the pure and 2-APY incorporated PVDF-HFP/PEO blend electrolytes were estimated to be 4.53×10-5 and 1.87×10-4 Scm-1 respectively. The UV-vis absorption spectroscopy was carried out for the pure and different wt% of g-C3N4/TiO2 composites coated FTO films after N3 dye-sensitization. The 10 wt% g-C3N4/TiO2 composite film showed a maximum absorption compared to the others. The DSSC assembled with 10 wt% g-C3N4/TiO2 as photoanode using the pure polymer blend electrolyte exhibited a power conversion efficiency (PCE) of 3.17% , which was superior than that of DSSC based pure TiO2 (2.46%). However, the PCE was increased to 4.73% for the DSSC assembled using 10 wt% g-C3N4/TiO2 as photoanode with 2-APY incorporated polymer blend electrolyte. Hence, the present study is a successful attempt to provide a new pathway to enhance the performance of DSSCs.

  11. The high surface energy of NiO {110} facets incorporated into TiO2 hollow microspheres by etching Ti plate for enhanced photocatalytic and photoelectrochemical activity

    NASA Astrophysics Data System (ADS)

    Li, Jian; Cui, Hongzhi; Song, Xiaojie; Wei, Na; Tian, Jian

    2017-02-01

    We present a rational design for the controllable synthesis of NiO/TiO2 hollow microspheres (NTHMs) with Ti plate via a one-pot template-free synthesis strategy. Specifically, to enhance the formation of hollow microspheres, part of the titanium source is provided by the Ti plate. The hollow spherical NiO/TiO2 particles possess unique microstructural characteristics, namely, a higher specific surface area (∼65.82 m2 g-1), a larger mesoporous structure (∼7.79 nm), and hierarchical nanoarchitectures connected with mesopores within the shell (monodispersed size of ∼1 μm and shell thickness of ∼80 nm). In addition, as a cocatalyst for improved catalytic activity, the incorporated NiO nanoparticles with exposed high surface energy {110} facets displayed an outstanding performance. It has been proven that this facile nanostructure possesses remarkably high photoelectrochemical and photocatalytic activities. The main mechanism for enhancement of photocatalytic activity is attributed to the construction of p-n junctions with an inner electric field between TiO2 and NiO, which can dramatically enhance the separation efficiency of the photogenerated electron-hole pairs. This strategy could be applied to fabricate mixed metal oxide hollow microspheres toward the photoelectrochemical catalysis.

  12. Simultaneous degradation of ofloxacin and recovery of Cu(II) by photoelectrocatalysis with highly ordered TiO2 nanotubes.

    PubMed

    Liu, Lan; Li, Ruizhen; Liu, Yong; Zhang, Jingdong

    2016-05-05

    A photoelectrocatalytic system for removal of ofloxacin and Cu(2+) complex was developed. In such a photoelectrocatalytic system, highly ordered titanium dioxide nanotubes served as a highly active photoanode for photoelectrocatalytic degradation of ofloxacin; and titanium plate was used as the cathode, on which Cu(2+) ions were electrodeposited. Compared with other treatment methods including photocatalysis, electrochemistry and direct photolysis, photoelectrocatalytic technique exhibited the highest removal efficiency for either ofloxacin or Cu(2+). To obtain the optimum photoelectrocatalytic operation conditions, some influencing factors such as current, pH and supporting electrolyte concentration were investigated systematically. The mutual influence analysis indicated that the photoelectrocatalytic removal efficiency of ofloxacin was first promoted by Cu(2+) but was then suppressed with prolonging the treatment time; whereas the removal of Cu(2+) was always promoted by ofloxacin over the whole photoelectrocatalytic treatment process. Furthermore, the photoelectrocatalytic removal of ofloxacin -Cu(2+) was studied by differential pulse voltammetry and high-performance liquid chromatography-mass spectrometry. The results indicated that although Cu(2+) influenced the removal rate of ofloxacin, it did not change the degradation mechanism of ofloxacin. The formation of an electroactive intermediate product during the photoelectrocatalytic process was clearly observed by voltammetric analysis. Based on intermediate products identified by high-performance liquid chromatography-mass spectrometry, a possible photoelectrocatalytic removal mechanism for ofloxacin -Cu(2+) was proposed.

  13. Cytocompatibility and antibacterial activity of titania nanotubes incorporated with gold nanoparticles.

    PubMed

    Yang, Tingting; Qian, Shi; Qiao, Yuqing; Liu, Xuanyong

    2016-09-01

    TiO2 nanotubes prepared by electrochemical anodization have received considerable attention in the biomedical field. In this work, different amounts of gold nanoparticles were immobilized onto TiO2 nanotubes using 3-aminopropyltrimethoxysilane as coupling agent. Field emission scanning electron microscopy and X-ray photoelectron spectroscopy were used to investigate the surface morphology and composition. Photoluminescence spectra and surface zeta potential were also measured. The obtained results indicate that the surface modified gold nanoparticles can significantly enhance the electron storage capability and reduce the surface zeta potential compared to pristine TiO2 nanotubes. Moreover, the surface modified gold nanoparticles can stimulate initial adhesion and spreading of rat bone mesenchymal stem cells as well as proliferation, while the osteogenous performance of TiO2 nanotubes will not be reduced. The gold-modified surface presents moderate antibacterial effect on both Staphylococcus aureus and Escherichia coli. It should be noted that the surface modified fewer gold nanoparticles has better antibacterial effect compared to the surface of substantial modification of gold nanoparticles. Our study illustrates a composite surface with favorable cytocompatibility and antibacterial effect and provides a promising candidate for orthopedic and dental implant.

  14. Photocatalysis applications of some hybrid polymeric composites incorporating TiO2 nanoparticles and their combinations with SiO2/Fe2O3.

    PubMed

    Chibac, Andreea Laura; Buruiana, Tinca; Melinte, Violeta; Buruiana, Emil C

    2017-01-01

    Polymer nanocomposites containing titanium oxide nanoparticles (TiO2 NPs) combined with other inorganic components (Si-O-Si or/and γ-Fe2O3) were prepared by the dispersion of premade NPs (nanocrystalline TiO2, TiO2/SiO2, TiO2/Fe2O3, TiO2/SiO2/Fe2O3) within a photopolymerizable urethane dimethacrylate (polytetrahydrofuran-urethane dimethacrylate, PTHF-UDMA). The physicochemical characterization of nanoparticles and hybrid polymeric composites with 10 wt % NPs (S1-S4) was realized through XRD, TEM and FTIR analyses. The mean size (10-30 nm) and the crystallinity of the NPs varied as a function of the inorganic constituent. The catalytic activity of these hybrid films was tested for the photodegradation of phenol, hydroquinone and dopamine in aqueous solution under UV or visible-light irradiation. The best results were obtained for the films with TiO2/Fe2O3 or TiO2/SiO2/Fe2O3 NPs. The degradation of the mentioned model pollutants varied between 71% and 100% (after 250 min of irradiation) depending on the composition of the hybrid film tested and the light applied (UV-visible light). Also, it was established that such hybrid films can be reused at least for five cycles, without losing too much of the photocatalytic efficiency (ca. 7%). These findings could have implications in the development of new nanocatalysts.

  15. Photocatalysis applications of some hybrid polymeric composites incorporating TiO2 nanoparticles and their combinations with SiO2/Fe2O3

    PubMed Central

    Buruiana, Tinca; Melinte, Violeta; Buruiana, Emil C

    2017-01-01

    Polymer nanocomposites containing titanium oxide nanoparticles (TiO2 NPs) combined with other inorganic components (Si–O–Si or/and γ-Fe2O3) were prepared by the dispersion of premade NPs (nanocrystalline TiO2, TiO2/SiO2, TiO2/Fe2O3, TiO2/SiO2/Fe2O3) within a photopolymerizable urethane dimethacrylate (polytetrahydrofuran-urethane dimethacrylate, PTHF-UDMA). The physicochemical characterization of nanoparticles and hybrid polymeric composites with 10 wt % NPs (S1–S4) was realized through XRD, TEM and FTIR analyses. The mean size (10–30 nm) and the crystallinity of the NPs varied as a function of the inorganic constituent. The catalytic activity of these hybrid films was tested for the photodegradation of phenol, hydroquinone and dopamine in aqueous solution under UV or visible-light irradiation. The best results were obtained for the films with TiO2/Fe2O3 or TiO2/SiO2/Fe2O3 NPs. The degradation of the mentioned model pollutants varied between 71% and 100% (after 250 min of irradiation) depending on the composition of the hybrid film tested and the light applied (UV–visible light). Also, it was established that such hybrid films can be reused at least for five cycles, without losing too much of the photocatalytic efficiency (ca. 7%). These findings could have implications in the development of new nanocatalysts. PMID:28243566

  16. High-performance large-scale flexible dye-sensitized solar cells based on anodic TiO2 nanotube arrays.

    PubMed

    Jen, Hsiu-Ping; Lin, Meng-Hung; Li, Lu-Lin; Wu, Hui-Ping; Huang, Wei-Kai; Cheng, Po-Jen; Diau, Eric Wei-Guang

    2013-10-23

    A simple strategy to fabricate flexible dye-sensitized solar cells involves the use of photoanodes based on TiO2 nanotube (TNT) arrays with rear illumination. The TNT films (tube length ∼35 μm) were produced via anodization, and sensitized with N719 dye for photovoltaic characterization. Pt counter electrodes of two types were used: a conventional FTO/glass substrate for a device of rigid type and an ITO/PEN substrate for a device of flexible type. These DSSC devices were fabricated into either a single-cell structure (active area 3.6×0.5 cm2) or a parallel module containing three single cells (total active area 5.4 cm2). The flexible devices exhibit remarkable performance with efficiencies η=5.40% (single cell) and 4.77% (parallel module) of power conversion, which outperformed their rigid counterparts with η=4.87% (single cell) and 4.50% (parallel model) under standard one-sun irradiation. The flexible device had a greater efficiency of conversion of incident photons to current and a broader spectral range than the rigid device; a thinner electrolyte layer for the flexible device than for the rigid device is a key factor to improve the light-harvesting ability for the TNT-DSSC device with rear illumination. Measurements of electrochemical impedance spectra show excellent catalytic activity and superior diffusion characteristics for the flexible device. This technique thus provides a new option to construct flexible photovoltaic devices with large-scale, light-weight, and cost-effective advantages for imminent applications in consumer electronics.

  17. Ultrasensitive photoelectrochemical immunoassay for matrix metalloproteinase-2 detection based on CdS:Mn/CdTe cosensitized TiO2 nanotubes and signal amplification of SiO2@Ab2 conjugates.

    PubMed

    Fan, Gao-Chao; Han, Li; Zhu, Hua; Zhang, Jian-Rong; Zhu, Jun-Jie

    2014-12-16

    An ultrasensitive photoelectrochemical sandwich immunoassay was developed to detect matrix metalloproteinase-2 (MMP-2, antigen, Ag) based on CdS:Mn/CdTe cosensitized TiO2 nanotubes (TiO2-NTs) and signal amplification of SiO2@Ab2 conjugates. Specifically, the TiO2-NTs electrode was first deposited with CdS:Mn by successive ionic layer adsorption and reaction technique and then further coated with CdTe quantum dots (QDs) via the layer-by-layer method, forming TiO2-NTs/CdS:Mn/CdTe cosensitized structure, which was employed as a matrix to immobilize capture MMP-2 antibodies (Ab1); whereas, SiO2 nanoparticles were coated with signal MMP-2 antibodies (Ab2) to form SiO2@Ab2 conjugates, which were used as signal amplification elements via the specific antibody-antigen immunoreaction between Ag and Ab2. The ultrahigh sensitivity of this immunoassay derived from the two major reasons as below. First, the TiO2-NTs/CdS:Mn/CdTe cosensitized structure could adequately absorb the light energy, dramatically promote electron transfer, and effectively inhibit the electron-hole recombination, resulting in significantly enhanced photocurrent intensity of the sensing electrode. However, in the presence of target Ag, the immobilized SiO2@Ab2 conjugates could evidently increase the steric hindrance of the sensing electrode and effectively depress the electron transfer, leading to obviously decreased photocurrent intensity. Accordingly, the well-designed photoelectrochemical immunoassay exhibited a low detection limit of 3.6 fg/mL and a wide linear range from 10 fg/mL to 500 pg/mL for target Ag detection. Meanwhile, it also presented good reproducibility, specificity, and stability and might open a new promising platform for the detection of other important biomarkers.

  18. Development of a TiO2 modified optical fiber electrode and its incorporation into a photoelectrochemical reactor for wastewater treatment.

    PubMed

    Esquivel, K; Arriaga, L G; Rodríguez, F J; Martínez, L; Godínez, Luis A

    2009-08-01

    Electrochemical advanced oxidation processes (EAOPs) are used to chemically burn non biodegradable complex organic compounds that are present in polluted effluents. A common approach involves the use of TiO2 semiconductor substrates as either photocatalytic or photoelectrocatalytic materials in reactors that produce a powerful oxidant (hydroxyl radical) that reacts with pollutant species. In this context, the purpose of this work is to develop a new TiO2 based photoanode using an optic fiber support. The novel arrangement of a TiO2 layer positioned on top of a surface modified optical fiber substrate, allowed the construction of a photoelectrochemical reactor that works on the basis of an internally illuminated approach. In this way, a semi-conductive optical fiber modified surface was prepared using 30 microm thickness SnO2:Sb films on which the photoactive TiO2 layer was electrophoretically deposited. UV light transmission experiments were conducted to evaluate the transmittance along the optical fiber covered with SnO2:Sb and TiO2 showing that 43% of UV light reached the optical fiber tip. With different illumination configurations (external or internal), it was possible to get an increase in the amount of photo-generated H(2)O(2) close to 50% as compared to different types of TiO2 films. Finally, the electro-Fenton photoelectrocatalytic Oxidation process studied in this work was able to achieve total color removal of Azo orange II dye (15 mg L(-1)) and a 57% removal of total organic carbon (TOC) within 60 min of degradation time.

  19. TiO2 anode materials for lithium-ion batteries with different morphology and additives

    NASA Astrophysics Data System (ADS)

    Liu, Xiang; Ng, Yip Hang; Leung, Yu Hang; Liu, Fangzhou; Djurišic, Aleksandra B.; Xie, Mao Hai; Chan, Wai Kin

    2014-03-01

    Electrochemical performances of different TiO2 nanostructures, TiO2/CNT composite and TiO2 with titanium isopropoxide (TTIP) treatment anode were investigated. For different TiO2 nanostructures, we investigated vertically aligned TiO2 nanotubes on Ti foil and TiO2 nanotube-powders fabricated by rapid breakdown anodization technique. The morphology of the prepared samples was characterized by scanning probe microscopy (SEM). The electrochemical lithium storage abilities were studied by galvanostatic method. In addition, carbon nanotubes (CNT) additives and solution treatment process of TiO2 anode were investigated, and the results show that the additives and treatment could enhance the cycling performance of the TiO2 anode on lithium ion batteries.

  20. New metallic alloys incorporating fullerenes and carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Doome, R. J.; Fonseca, A.; Nagy, J. B.

    1998-08-01

    In order to open new routes to fullerenes application, we have investigated the effect of fullerenes and nanotubes in metallic alloys. Fullerenes mixture and carbon nanotubes have been used as new carbon sources in the synthesis of metallic alloys (Al, Fe and Ni). After melting under inert atmosphere, macroscopic homogeneous alloys were obtained with iron and nickel but the aluminium based alloys looked rather inhomogeneous due to an incomplete melting. From the samples analysis by chemical reactions and XPS, it was concluded that the carbon is essentially located on the alloy surface as carbide and sp2 structures. Except for the aluminium based alloy where some fullerenes were still detected, thermal treatment as well as metal catalytic effect led to the decomposition of the fullerenes in the alloys. Nevertheless, carbon nanotubes kept their structure and were trapped in the alloys. The hardness of these new alloys were determined and compared to values of common alloys incorporating graphite and norit-A as carbon sources. The preliminary results showed slightly higher hardness values for alloys incorporating fullerenes and weaker values for alloys incorporating carbon nanotubes.

  1. Enhancement of Glycerol Steam Reforming Activity and Thermal Stability by Incorporating CeO2 and TiO2 in Ni- and Co-MCM-41 Catalysts

    NASA Astrophysics Data System (ADS)

    Dade, William N.

    Hydrogen (H2) has many applications in industry with current focus shifted to production of hydrocarbon fuels and valuable oxygenates using the Fischer-Tropsch technology and direct use in proton exchange membrane fuel cell (PEMFC). Hydrogen is generally produced via steam reforming of natural gas or alcohols like methanol and ethanol. Glycerol, a by-product of biodiesel production process, is currently considered to be one of the most attractive sources of sustainable H2 due to its high H/C ratio and bio-based origin. Ni and Co based catalysts have been reported to be active in glycerol steam reforming (GSR); however, deactivation of the catalysts by carbon deposition and sintering under GSR operating conditions is a major challenge. In this study, a series of catalysts containing Ni and Co nanoparticles incorporated in CeO2 and TiO2 modified high surface area MCM-41 have been synthesized using one-pot method. The catalysts are tested for GSR (at H2O/Glycerol mole ratio of 12 and GHSV of 2200 h-1) to study the effect of support modification and reaction temperature (450 - 700 °C) on the product selectivity and long term stability. GSR results revealed that all the catalysts performed significantly well exhibiting over 85% glycerol conversion at 650 °C except Ni catalysts that showed better low temperature activities. Deactivation studies of the catalysts conducted at 650 °C indicated that the Ni-TiO2-MCM-41 and Ni-CeO 2-MCM-41 were resistant to deactivation with ˜100% glycerol conversion for 40 h. In contrast, Co-TiO2-MCM-41 perform poorly as the catalyst rapidly deactivated after 12 h to yield ˜20% glycerol conversion after 40 h. The WAXRD and TGA-DSC analyses of spent catalysts showed a significant amount of coke deposition that might explain catalysts deactivation. The flattening shape of the original BET type IV isotherm with drastic reduction of catalyst surface area can also be responsible for observed drop in catalysts activities.

  2. Free standing TiO2 nanotube array electrodes with an ultra-thin Al2O3 barrier layer and TiCl4 surface modification for highly efficient dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Gao, Xianfeng; Guan, Dongsheng; Huo, Jingwan; Chen, Junhong; Yuan, Chris

    2013-10-01

    Dye sensitized solar cells were fabricated with free standing TiO2 nanotube (TNT) array films, which were prepared by template assisted atomic layer deposition (ALD) with precise wall thickness control. Efforts to improve the photovoltaic performance were made by using Al2O3 barrier layer coating in conjunction with TiCl4 surface modification. An Al2O3 thin layer was deposited on the TNT electrode by ALD to serve as the charge recombination barrier, but it suffers from the drawback of decreasing the photoelectron injection from dye into TiO2 when the barrier layer became too thick. With the TiCl4 treatment in combination with optimal thickness coating, this problem could be avoided. The co-surface treated electrode presents superior surface property with low recombination rate and good electron transport property. A high conversion efficiency of 8.62% is obtained, which is about 1.8 times that of the device without surface modifications.Dye sensitized solar cells were fabricated with free standing TiO2 nanotube (TNT) array films, which were prepared by template assisted atomic layer deposition (ALD) with precise wall thickness control. Efforts to improve the photovoltaic performance were made by using Al2O3 barrier layer coating in conjunction with TiCl4 surface modification. An Al2O3 thin layer was deposited on the TNT electrode by ALD to serve as the charge recombination barrier, but it suffers from the drawback of decreasing the photoelectron injection from dye into TiO2 when the barrier layer became too thick. With the TiCl4 treatment in combination with optimal thickness coating, this problem could be avoided. The co-surface treated electrode presents superior surface property with low recombination rate and good electron transport property. A high conversion efficiency of 8.62% is obtained, which is about 1.8 times that of the device without surface modifications. Electronic supplementary information (ESI) available: UV-Vis spectra of desorbed N719 dyes from

  3. A novel solid-state electrochemiluminescence sensor based on Ru(bpy)32 + immobilization on TiO2 nanotube arrays and its application for detection of amines in water

    NASA Astrophysics Data System (ADS)

    Xu, Zhihua; Yu, Jiaguo

    2010-06-01

    Many amines are proven or suspected to be carcinogenic and have been implicated in inducing cancer of the bladder. Therefore, the monitoring of their levels in environmental samples is important for the protection of health and the environment. Herein, a novel method for effective immobilization of Ru(bpy)32 + on the electrode surface of TiO2 nanotube arrays (TNs) is developed for the first time. The method involves Ru(bpy)32 + spontaneously adsorbed on the surface of negatively charged TiO2 nanotubes due to electrostatic interaction to produce a Ru(bpy)32 + /TNs/Ti (Ru-TNs-Ti) solid-state electrochemiluminescence (ECL) sensor. The prepared solid-state sensor was used to detect the changes of concentrations of pollutant tripropylamine (TPA) in water. The sensor exhibits excellent ECL behavior, very good stability and high sensitivity. This study may provide new insight into the design and preparation of an advanced solid-state ECL sensor for monitoring of amines in water.

  4. Engineered Solution-Liquid-Solid Growth of a "Treelike" 1D/1D TiO2 Nanotube-CdSe Nanowire Heterostructure: Photoelectrochemical Conversion of Broad Spectrum of Solar Energy.

    PubMed

    Mukherjee, Bratindranath; Sarker, Swagotom; Crone, Eric; Pathak, Pawan; Subramanian, Vaidyanathan R

    2016-12-07

    This work presents a hitherto unreported approach to assemble a 1D oxide-1D chalcogenide heterostructured photoactive film. As a representative system, bismuth (Bi) catalyzed 1D CdSe nanowires are directly grown on anodized 1D TiO2 nanotube (T_NT). A combination of the reductive successive-ionic-layer-adsorption-reaction (R-SILAR) and the solution-liquid-solid (S-L-S) approach is implemented to fabricate this heterostructured assembly, reported in this 1D/1D form for the first time. XRD, SEM, HRTEM, and elemental mapping are performed to systematically characterize the deposition of bismuth on T_NT and the growth of CdSe nanowires leading to the evolution of the 1D/1D heterostructure. The resulting "treelike" photoactive architecture demonstrates UV-visible light-driven electron-hole pair generation. The photoelectrochemical results highlight: (i) the formation of a stable n-n heterojunction between TiO2 nanotube and CdSe nanowire, (ii) an excellent correlation between the absorbance vis-à-vis light conversion efficiency (IPCE), and (iii) a photocurrent density of 3.84 mA/cm(2). This proof-of-concept features the viability of the approach for designing such complex 1D/1D oxide-chalcogenide heterostructures that can be of interest to photovoltaics, photocatalysis, environmental remediation, and sensing.

  5. Dark pulse generation in fiber lasers incorporating carbon nanotubes.

    PubMed

    Liu, H H; Chow, K K

    2014-12-01

    We demonstrate the generation of dark pulses from carbon nanotube (CNT) incorporated erbium-doped fiber ring lasers with net anomalous dispersion. A side-polished fiber coated with CNT layer by optically-driven deposition method is embedded into the laser in order to enhance the birefringence and nonlinearity of the laser cavity. The dual-wavelength domain-wall dark pulses are obtained from the developed CNT-incorporated fiber laser at a relatively low pump threshold of 50.6 mW. Dark pulses repeated at the fifth-order harmonic of the fundamental cavity frequency are observed by adjusting the intra-cavity polarization state.

  6. Self-assembled TiO(2) nanotube arrays by anodization of titanium in diethylene glycol: approach to extended pore widening.

    PubMed

    Yoriya, Sorachon; Grimes, Craig A

    2010-01-05

    We report on the formation of titanium dioxide nanotube arrays having the largest known pore size, approximately 350 nm diameter. The nanotube arrays are synthesized by Ti foil anodization in a diethylene glycol electrolyte containing low (0.5-2%) concentrations of hydrofluoric acid. The large pore size nanotube arrays are achieved with extended anodization durations of approximately 120 h, with the anodization duration showing a more significant effect on pore diameter than the anodization voltage. It appears that the combined effects of hydrofluoric acid content and anodization duration determine the lateral etching rate of the nanotubes, leading to the larger pore size nanotubes.

  7. Free standing TiO2 nanotube array electrodes with an ultra-thin Al2O3 barrier layer and TiCl4 surface modification for highly efficient dye sensitized solar cells.

    PubMed

    Gao, Xianfeng; Guan, Dongsheng; Huo, Jingwan; Chen, Junhong; Yuan, Chris

    2013-11-07

    Dye sensitized solar cells were fabricated with free standing TiO2 nanotube (TNT) array films, which were prepared by template assisted atomic layer deposition (ALD) with precise wall thickness control. Efforts to improve the photovoltaic performance were made by using Al2O3 barrier layer coating in conjunction with TiCl4 surface modification. An Al2O3 thin layer was deposited on the TNT electrode by ALD to serve as the charge recombination barrier, but it suffers from the drawback of decreasing the photoelectron injection from dye into TiO2 when the barrier layer became too thick. With the TiCl4 treatment in combination with optimal thickness coating, this problem could be avoided. The co-surface treated electrode presents superior surface property with low recombination rate and good electron transport property. A high conversion efficiency of 8.62% is obtained, which is about 1.8 times that of the device without surface modifications.

  8. Influence of Cu2+ dopant in optical property of CdTe quantum dots and photoelectrochemical performance of CdTe:Cu2+/TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Chen, Qian; Geng, Yue; Zhou, Chunyan; Song, Jiahui; Zhou, Liya

    2016-05-01

    A novel one-step synthesis process was used to prepare CdTe:Cu2+/TiO2 nanotube arrays (TNTAs). X-ray powder diffraction and high-resolution transmission electron microscopy analyses confirmed that the obtained CdTe:Cu2+ quantum dots (QDs) possess cubic structures, which are approximately spherical, and a small particle size (2.95 nm). The photoluminescent and UV-visible absorption spectra of CdTe:Cu2+ QDs also display an obvious redshift, which was attributed to the replacement of Cd2+ with Cu2+. Compared with that of the TNTAs and CdTe/TNTAs, the photoelectric conversion efficiency of CdTe:5% Cu2+/TNTAs increased by 785.7% and 103.3%, respectively. The incident photo-to-current conversion efficiency of CdTe:5% Cu2+/TNTAs was 50.6%, which indicated the potential use of QDs in photochemical solar cells.

  9. Tunable, Highly Ordered TiO2 Nanotube Arrays on Indium Tin Oxide Coated PET for Flexible Bio-sensitized Solar Cells

    DTIC Science & Technology

    2011-08-01

    crystallite form. When annealed at temperatures between 300 and 500 ° C for about 3 h, the anatase crystalline form of TiO2 can be obtained. At higher...L. Jpn. J. Appl. Phys. 2006, 45, L638. 5. Koops, S. E.; O’Regan, B. C .; Barnes , P.R.F.; Durrant, J. R. J. Am. Chem. Soc. 2009, 131, 4808. 6...Oxide Coated PET for Flexible Bio-sensitized Solar Cells JOSHUA J. MARTIN, UNIVERSITY OF DELAWARE MENTORS: DR. SHASHI KARNA AND DR. MARK GRIEP U.S

  10. Synthesis of rare earth doped TiO2 nanorods as photocatalysts for lignin degradation

    DOE PAGES

    Song, Liang; Zhao, Xueyuan; Cao, Lixin; ...

    2015-09-10

    In this paper, a two-step process is developed to synthesize rare earth doped titania nanorods (RE–TiO2 NRs) as photocatalysts for efficient degradation of lignin under simulated sunlight irradiation. In this approach, protonated titanate nanotubes with layered structures were first prepared by a hydrothermal approach, and rare earth metal ions were subsequently bound to the negatively charged surface of the synthesized titanate via electrostatic incorporation. The as-synthesized RE–TiO2 NRs after calcination generally showed much higher photocatalytic efficiencies than those of undoped TiO2 NRs or the commercial P25 TiO2 photocatalyst. Using methyl orange (MO) as a probing molecule, we demonstrate that Eu–TiO2more » NRs are among the best for degrading MO, with an observed rate constant of 4.2 × 10-3 s-1. The La3+, Sm3+, Eu3+ and Er3+ doped TiO2 NRs also showed higher photocatalytic efficiencies in degrading MO than the commercial P25 TiO2. Finally, we further demonstrate that lignin can be photodegraded effectively and rapidly at room temperature under simulated sunlight through two reaction routes, which could be important in controlling ways of lignin depolymerization or the formation of reaction products.« less

  11. Removing Structural Disorder from Oriented TiO2 Nanotube Arrays: Reducing the Dimensionality of Transport and Recombination in Dye-Sensitized Solar Cells

    SciTech Connect

    Zhu, K.; Vinzant, T. B.; Neale, N. R.; Frank, A. J.

    2007-01-01

    We report on the influence of morphological disorder, arising from bundling of nanotubes (NTs) and microcracks in films of oriented TiO{sub 2} NT arrays, on charge transport and recombination in dye-sensitized solar cells (DSSCs). Capillary stress created during evaporation of liquids from the mesopores of dense TiO{sub 2} NT arrays was of sufficient magnitude to induce bundling and microcrack formation. The average lateral deflection of the NTs in the bundles increased with the surface tension of the liquids and with the film thicknesses. The supercritical CO{sub 2} drying technique was used to produce bundle-free and crack-free NT films. Charge transport and recombination properties of sensitized films were studied by frequency-resolved modulated photocurrent/photovoltage spectroscopies. Transport became significantly faster with decreased clustering of the NTs, indicating that bundling creates additional pathways via intertube contacts. Removing such contacts alters the transport mechanism from a combination of one and three dimensions to the expected one dimension and shortens the electron-transport pathway. Reducing intertube contacts also resulted in a lower density of surface recombination centers by minimizing distortion-induced surface defects in bundled NTs. A causal connection between transport and recombination is observed. The dye coverage was greater in the more aligned NT arrays, suggesting that reducing intertube contacts increases the internal surface area of the films accessible to dye molecules. The solar conversion efficiency and photocurrent density were highest for DSSCs incorporating films with more aligned NT arrays owing to an enhanced light-harvesting efficiency. Removing structural disorder from other materials and devices consisting of nominally one-dimensional architectures (e.g., nanowire arrays) should produce similar effects.

  12. Enhanced photovoltaic performance of dye-sensitized solar cells based on NaYF4:Yb(3+), Er(3+)-incorporated nanocrystalline TiO2 electrodes.

    PubMed

    Zhu, Guang; Wang, Hongyan; Zhang, Quanxin; Zhang, Li

    2015-08-01

    Near infrared to visible up-conversion of light by rare earth ion-doped phosphors (NaYF4:Yb(3+), Er(3+)) that convert multiple photons of lower energy to higher energy photons offer new possibilities for improved performance of photovoltaic devices. Here, up-conversion phosphor NaYF4:Yb(3+), Er(3+) doped nanocrystalline TiO2 films are designed and used as a electrode for dye-sensitized solar cells, and the photovoltaic performance of DSSCs based on composite electrodes are investigated. The results show the cell with NaYF4:Yb(3+), Er(3+) achieves a power conversion efficiency of 7.65% under one sun illumination (AM 1.5G, 100mWcm(-2)), which is an increase of 14% compared to the cell without NaYF4:Yb(3+), Er(3+) (6.71%). The performance improvement is attributed to the dual effects of enhanced light harvesting from extended light absorption range and increased light scattering, and lower electron transfer resistance.

  13. The effects of hierarchical micro/nanosurfaces decorated with TiO2 nanotubes on the bioactivity of titanium implants in vitro and in vivo.

    PubMed

    Ding, Xianglong; Zhou, Lei; Wang, Jingxu; Zhao, Qingxia; Lin, Xi; Gao, Yan; Li, Shaobing; Wu, Jingyi; Rong, Mingdeng; Guo, Zehong; Lai, Chunhua; Lu, Haibin; Jia, Fang

    2015-01-01

    In the present work, a hierarchical hybrid micro/nanostructured titanium surface was obtained by sandblasting with large grit and acid etching (SLA), and nanotubes of different diameters (30 nm, 50 nm, and 80 nm) were superimposed by anodization. The effect of each SLA-treated surface decorated with nanotubes (SLA + 30 nm, SLA + 50 nm, and SLA + 80 nm) on osteogenesis was studied in vitro and in vivo. The human MG63 osteosarcoma cell line was used for cytocompatibility evaluation, which showed that cell adhesion and proliferation were dramatically enhanced on SLA + 30 nm. In comparison with cells grown on the other tested surfaces, those grown on SLA + 80 nm showed an enhanced expression of osteogenesis-related genes. Cell spread was also enhanced on SLA + 80 nm. A canine model was used for in vivo evaluation of bone bonding. Histological examination demonstrated that new bone was formed more rapidly on SLA-treated surfaces with nanotubes (especially SLA + 80 nm) than on those without nanotubes. All of these results indicate that SLA + 80 nm is favorable for promoting the activity of osteoblasts and early bone bonding.

  14. Synthesis and characterization of poly(methyl methacrylate)-based experimental bone cements reinforced with TiO2-SrO nanotubes.

    PubMed

    Khaled, S M Z; Charpentier, Paul A; Rizkalla, Amin S

    2010-08-01

    In an attempt to overcome existing limitations of experimental bone cements we here demonstrate a simple approach to synthesizing strontium-modified titania nanotubes (n-SrO-TiO(2) tubes) and functionalize them using the bifunctional monomer methacrylic acid. Then, using 'grafting from' polymerization with methyl methacrylate, experimental bone cements were produced with excellent mechanical properties, radiopacity and biocompatibility. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive spectroscopy mapping and backscattered SEM micrographs revealed a uniform distribution of SrO throughout the titanium matrix, with retention of the nanotubular morphology. Nanocomposites were then reinforced with 1, 2, 4 and 6 wt.% of the functionalized metal oxide nanotubes. Under the mixing and dispersion regime employed in this study, 2 wt.% appeared optimal, exhibiting a more uniform dispersion and stronger adhesion of the nanotubes in the poly(methyl methacrylate) matrix, as shown by TEM and SEM. Moreover, this optimum loading provided a significant increase in the fracture toughness (K(IC)) (20%) and flexural strength (40%) in comparison with the control matrix (unfilled) at P<0.05. Examination of the fracture surfaces by SEM showed that toughening was provided by the nanotubes interlocking with the acrylic matrix and crack bridging during fracture. On modifying the n-TiO(2) tubes with strontium oxide the nanocomposites exhibited a similar radiopacity to a commercial bone cement (CMW 1), while exhibiting a significant enhancement of osteoblast cell proliferation (242%) in vitro compared with the control at P<0.05.

  15. The effects of hierarchical micro/nanosurfaces decorated with TiO2 nanotubes on the bioactivity of titanium implants in vitro and in vivo

    PubMed Central

    Ding, Xianglong; Zhou, Lei; Wang, Jingxu; Zhao, Qingxia; Lin, Xi; Gao, Yan; Li, Shaobing; Wu, Jingyi; Rong, Mingdeng; Guo, Zehong; Lai, Chunhua; Lu, Haibin; Jia, Fang

    2015-01-01

    In the present work, a hierarchical hybrid micro/nanostructured titanium surface was obtained by sandblasting with large grit and acid etching (SLA), and nanotubes of different diameters (30 nm, 50 nm, and 80 nm) were superimposed by anodization. The effect of each SLA-treated surface decorated with nanotubes (SLA + 30 nm, SLA + 50 nm, and SLA + 80 nm) on osteogenesis was studied in vitro and in vivo. The human MG63 osteosarcoma cell line was used for cytocompatibility evaluation, which showed that cell adhesion and proliferation were dramatically enhanced on SLA + 30 nm. In comparison with cells grown on the other tested surfaces, those grown on SLA + 80 nm showed an enhanced expression of osteogenesis-related genes. Cell spread was also enhanced on SLA + 80 nm. A canine model was used for in vivo evaluation of bone bonding. Histological examination demonstrated that new bone was formed more rapidly on SLA-treated surfaces with nanotubes (especially SLA + 80 nm) than on those without nanotubes. All of these results indicate that SLA + 80 nm is favorable for promoting the activity of osteoblasts and early bone bonding. PMID:26635472

  16. Tracking areal lithium densities from neutron activation - quantitative Li determination in self-organized TiO2 nanotube anode materials for Li-ion batteries.

    PubMed

    Portenkirchner, E; Neri, G; Lichtinger, J; Brumbarov, J; Rüdiger, C; Gernhäuser, R; Kunze-Liebhäuser, J

    2017-03-28

    Nanostructuring of electrode materials is a promising approach to enhance the performance of next-generation, high-energy density lithium (Li)-ion batteries. Various experimental and theoretical approaches allow for a detailed understanding of solid-state or surface-controlled reactions that occur in nanoscaled electrode materials. While most techniques which are suitable for nanomaterial investigations are restricted to analysis widths of the order of Å to some nm, they do not allow for characterization over the length scales of interest for electrode design, which is typically in the order of mm. In this work, three different self-organized anodic titania nanotube arrays, comprising as-grown amorphous titania nanotubes, carburized anatase titania nanotubes, and silicon coated carburized anatase titania nanotubes, have been synthesized and studied as model composite anodes for use in Li-ion batteries. Their 2D areal Li densities have been successfully reconstructed with a sub-millimeter spatial resolution over lateral electrode dimensions of 20 mm exploiting the (6)Li(n,α)(3)H reaction, in spite of the extremely small areal Li densities (10-20 μg cm(-2) Li) in the nanotubular active material. While the average areal Li densities recorded via triton analysis are found to be in good agreement with the electrochemically measured charges during lithiation, triton analysis revealed, for certain nanotube arrays, areas with a significantly higher Li content ('hot spots') compared to the average. In summary, the presented technique is shown to be extremely well suited for analysis of the lithiation behavior of nanostructured electrode materials with very low Li concentrations. Furthermore, identification of lithiation anomalies is easily possible, which allows for fundamental studies and thus for further advancement of nanostructured Li-ion battery electrodes.

  17. Influence of annealing on optical and photovoltaic properties of nanostructured TiO2 films

    NASA Astrophysics Data System (ADS)

    Serikov, T. M.; Ibrayev, N. Kh; Smagulov, Zh Kh; Kuterbekov, К. А.

    2017-01-01

    Spectral and kinetic characteristics of the photoluminescence of TiO2 films obtained from TiO2 nanoparticles and nanotubes were studied. Luminescence spectra typical for the TiO2 with anatase structure were observed under UV excitation of the films. Heat treatment of the films at T=1273 K leads to a long-wavelength shift of the photoluminescence band with maximum at 850 nm, which corresponds to the rutile structure. The luminescence duration of rutile films is longer than the luminescence duration of the anatase films as for nanoparticles and for nanotubes. The photovoltaic properties of TiO2 films with different structures were investigated. It was established that anatase structured films have a higher photocurrent than the rutile structured film. By impedance spectroscopy method it was found that the electron transport resistance in the nanotube films is higher but the recombination rate is lower than in the TiO2 nanoparticle films.

  18. TiO2, SiO2, and Al2O3 coated nanopores and nanotubes produced by ALD in etched ion-track membranes for transport measurements

    NASA Astrophysics Data System (ADS)

    Spende, Anne; Sobel, Nicolas; Lukas, Manuela; Zierold, Robert; Riedl, Jesse C.; Gura, Leonard; Schubert, Ina; Montero Moreno, Josep M.; Nielsch, Kornelius; Stühn, Bernd; Hess, Christian; Trautmann, Christina; Toimil-Molares, Maria E.

    2015-08-01

    Low-temperature atomic layer deposition (ALD) of TiO2, SiO2, and Al2O3 was applied to modify the surface and to tailor the diameter of nanochannels in etched ion-track polycarbonate membranes. The homogeneity, conformity, and composition of the coating inside the nanochannels are investigated for different channel diameters (18-55 nm) and film thicknesses (5-22 nm). Small angle x-ray scattering before and after ALD demonstrates conformal coating along the full channel length. X-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy provide evidence of nearly stoichiometric composition of the different coatings. By wet-chemical methods, the ALD-deposited film is released from the supporting polymer templates providing 30 μm long self-supporting nanotubes with walls as thin as 5 nm. Electrolytic ion-conductivity measurements provide proof-of-concept that combining ALD coating with ion-track nanotechnology offers promising perspectives for single-pore applications by controlled shrinking of an oversized pore to a preferred smaller diameter and fine-tuning of the chemical and physical nature of the inner channel surface.

  19. Double-Side Co-Catalytic Activation of Anodic TiO2 Nanotube Membranes with Sputter-Coated Pt for Photocatalytic H2 Generation from Water/Methanol Mixtures.

    PubMed

    Cha, Gihoon; Altomare, Marco; Truong Nguyen, Nhat; Taccardi, Nicola; Lee, Kiyoung; Schmuki, Patrik

    2017-02-01

    Self-standing TiO2 nanotube layers in the form of membranes are fabricated by self-organizing anodization of Ti metal and a potential shock technique. The membranes are then decorated by sputtering different Pt amounts i) only at the top, ii) only at the bottom or iii) at both top and bottom of the tube layers. The Pt-decorated membranes are transferred either in tube top-up or in tube top-down configuration onto FTO slides and are investigated, after crystallization, as photocatalysts for H2 generation using either front or back-side light irradiation. Double-side Pt-decoration of the tube membranes leads to higher H2 generation rates (independently of tube and light-irradiation configuration) compared to membranes decorated at only one side with similar overall Pt amounts. The results suggest that this effect cannot be only ascribed to the overall amount of Pt co-catalyst as such but also to its distribution at both tube extremities. This leads to optimized light absorption and electron diffusion/transfer dynamics: the central part of the membranes acts as light-harvesting zone and electrons therein generated can diffuse towards the Pt/TiO2 active zones (tube extremities) where they can react with the environment and generate H2 .

  20. TiO2, SiO2, and Al2O3 coated nanopores and nanotubes produced by ALD in etched ion-track membranes for transport measurements.

    PubMed

    Spende, Anne; Sobel, Nicolas; Lukas, Manuela; Zierold, Robert; Riedl, Jesse C; Gura, Leonard; Schubert, Ina; Moreno, Josep M Montero; Nielsch, Kornelius; Stühn, Bernd; Hess, Christian; Trautmann, Christina; Toimil-Molares, Maria E

    2015-08-21

    Low-temperature atomic layer deposition (ALD) of TiO2, SiO2, and Al2O3 was applied to modify the surface and to tailor the diameter of nanochannels in etched ion-track polycarbonate membranes. The homogeneity, conformity, and composition of the coating inside the nanochannels are investigated for different channel diameters (18-55 nm) and film thicknesses (5-22 nm). Small angle x-ray scattering before and after ALD demonstrates conformal coating along the full channel length. X-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy provide evidence of nearly stoichiometric composition of the different coatings. By wet-chemical methods, the ALD-deposited film is released from the supporting polymer templates providing 30 μm long self-supporting nanotubes with walls as thin as 5 nm. Electrolytic ion-conductivity measurements provide proof-of-concept that combining ALD coating with ion-track nanotechnology offers promising perspectives for single-pore applications by controlled shrinking of an oversized pore to a preferred smaller diameter and fine-tuning of the chemical and physical nature of the inner channel surface.

  1. Enhancement of Photo-Current Conversion Efficiency in a CdS/CdSe Quantum-Dot-Sensitized Solar Cell Incorporated with Single-Walled Carbon Nanotubes.

    PubMed

    Park, Hyunjune; Lee, Jongtaek; Park, Taehee; Lee, Sanghun; Yi, Whikun

    2015-02-01

    Cadmium sulfide (CdS) and cadmium selenide (CdSe) are sequentially assembled onto a nanocrystalline TiO2 film to create a quantum-dot (QD)-sensitized solar cell application by a successive ionic layer adsorption and reaction (SILAR) method. The results show that CdS and CdSe QDs have a complementary effect in the performance of light harvest of solar cell. Single-walled carbon nanotubes (SWNTs) are incorporated with a CdS/CdSe QDs solar cell by mixing them with TiC2 film to enhance electron transfer. SWNTs are also sprayed onto CdSe QDs (SWNTs onto CdSe) to apply p+ type properties of SWNTs. Absorbance is increased in a wide wavelength range. In particular, cells having the sprayed SWNTs onto the QDs show a clear increase in absorbance at a low wavelength region. The fill factor of CdS/CdSe QDs solar cell with SWNTs is higher than that without SWNTs, indicating the decrease in loss of electron from TiO2 to QDs. Short-circuit current in a QD-sensitized solar cell having SWNTs on CdSe shows maximum value. Photo-current conversion efficiency of cells is increased in both cell types containing SWNTs at 10~17% compared with pristine cells. We expect that solar cells using SWNTs will affect future energy technology and devices.

  2. Spherical TiO2 aggregates with different building units for dye-sensitized solar cells.

    PubMed

    Liu, Zhaohui; Su, Xunjia; Hou, Genliang; Bi, Song; Xiao, Zhou; Jia, Haipeng

    2013-09-07

    Tailoring the architectures of spherical TiO2 aggregates is crucial to obtain superior photovoltaic properties and promote their application in dye-sensitized solar cells (DSSCs). Herein, we synthesized spherical TiO2 aggregates using different building units, including nanocrystallites, nanorods, nanosheets, and nanotubes, via a hydrothermal method, and studied the effect of the building units on the performances of DSSCs. The aggregates assembled by uniform nanosheet and nanotube building units were synthesized with the use of spherical TiO2 nanorod aggregates as titanium sources in an alkaline hydrothermal reaction. Compared with TiO2 nanoparticles, the spherical TiO2 aggregates possess higher surface area, more efficient light scattering ability, and better electron transport properties. Among the four types of spherical TiO2 aggregates; the nanorod, nanotube, and nanosheet aggregates demonstrate better electron transport properties than the nanocrystallite aggregates; the nanotube and nanosheet aggregates exhibit more efficient light scattering than the nanocrystallite and nanorod aggregates; and the nanotube aggregates show the highest surface area. Thus the DSSC based on nanotube aggregates exhibited the highest energy conversion efficiency of 7.48%, which is 16.0%, 9.7%, and 19.5% higher than those of the DSSCs based on the nanosheet, nanorod, and nanocrystallite aggregates, respectively.

  3. High Cyclability of Ionic Liquid-Produced TiO2 Nanotube Arrays As an Anode Material for Lithium-Ion Batteries

    SciTech Connect

    Li, Huaqing; Martha, Surendra K; Unocic, Raymond R; Luo, Huimin; Dai, Sheng; Qu, Jun

    2012-01-01

    TiO{sub 2} nanotubes (NTs) are considered as a potential SEI-free anode material for Li-ion batteries to offer enhanced safety. Organic solutions, dominatingly ethylene glycol (EG)-based, have widely been used for synthesizing TiO{sub 2} NTs via anodization because of their ability to generate long tubes and well-aligned structures. However, it has been revealed that the EG-produced NTs are composited with carbonaceous decomposition products of EG, release of which during the tube crystallization process inevitably causes nano-scale porosity and cracks. These microstructural defects significantly deteriorate the NTs charge transport efficiency and mechanical strength/toughness. Here we report using ionic liquids (ILs) to anodize titanium to grow low-defect TiO{sub 2} NTs by reducing the electrolyte decomposition rate (less IR drop due to higher electrical conductivity) as well as the chance of the decomposition products mixing into the TiO{sub 2} matrix (organic cations repelled away). Promising electrochemical results have been achieved when using the IL-produced TiO{sub 2} NTs as an anode for Li-ion batteries. The ILNTs demonstrated excellent capacity retention without microstructural damage for nearly 1200 cycles of charge-discharge, while the NTs grown in a conventional EG solution totally pulverized in cycling, resulting in significant capacity fade.

  4. Preferential adsorption behavior of methylene blue dye onto surface hydroxyl group enriched TiO2 nanotube and its photocatalytic regeneration.

    PubMed

    Natarajan, Thillai Sivakumar; Bajaj, Hari C; Tayade, Rajesh J

    2014-11-01

    The present manuscript focus on the synthesis of surface hydroxyl group enriched titanium dioxide nanotube (TNT) by hydrothermal method for preferential adsorption of methylene blue (MB) dye. The mixture of methylene blue (MB) and rhodamine B (RhB) dye was used to study the preferential adsorption nature of TNT. The synthesized TNT were characterized by various techniques such as powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption, and ammonia-temperature programmed desorption (NH3-TPD) analysis. Result demonstrated that enhancement in the surface area of TNT and higher number of hydroxyl group on the surface of TNT. In the binary mixture, the adsorption of MB dye was 12.9 times higher as compared to RhB dye, which clearly indicated the preferential adsorption of MB dye on TNT surface. The preferential interaction of MB on TNT is due to the electrostatic interaction between the cationic MB and negatively charged TNT surface. The preferential adsorption of MB dye was studied by applying Langmuir, Freundlich and Sips isotherm; pseudo-first and second-order kinetic model. Furthermore, the regeneration of dye adsorbed TNT was carried out by eco-friendly photocatalytic process under the irradiation of ultraviolet light.

  5. Hydrogen production from formic acid solution by modified TiO2 and titanate nanotubes in a two-step system under visible light irradiation.

    PubMed

    Yeh, H M; Lo, S L; Chen, M J; Chen, H Y

    2014-01-01

    Hydrogen gas is one of the most promising renewable energy sources, and the final product of hydrogen combustion is nothing but water. However, it is still a big challenge to produce hydrogen and store it. Many studies have been conducted into produce hydrogen from water using photocatalysts. Z-scheme photocatalysis is a two-photocatalyst system that comprises a hydrogen catalyst and an oxygen catalyst to produce hydrogen and oxygen respectively. Compared to the one-step system, the two-step system can promote the efficiency of water splitting. In addition, formic acid (FA) is a convenient hydrogen-storage material and can be safely handled in aqueous solutions. Therefore, this study investigated the photocatalytic conversion of FA solution to hydrogen using visible light with several types of hydrogen catalysts (CdS/titanate nanotubes (TNTs), CdS/TiO2, Pt/CdS/TNTs) and WO3 as the oxygen catalyst. The results showed that the yield of hydrogen with CdS/TNTs + WO3 was much higher than with CdS/TiO2 + WO3. Moreover, coating the photocatalysts with metal could further promote the reaction. The optimal platinum loading was 0.01 wt%, and the hydrogen production achieved was 852.5 μmol · h(-1) with 20 vol% FA solution.

  6. Optimized dispersion of conductive agents for enhanced Li-storage performance of TiO2

    NASA Astrophysics Data System (ADS)

    Han, Moyan; Chen, Ge

    2016-12-01

    Novel TiO2/carbon (TiO2/C) composites have been synthesized by a layer-by-layer deposition method, with electrostatic interaction. The addition of carbon conductive agents enhances the electrochemical performance of TiO2. Carbon for these has been sourced 0D nitrogen-doped carbon, 1D carbon nanotubes and 2D graphene. The as-obtained TiO2/C composites show carbon nanotubes and titanium dioxide coaxial nanocables anchored on the graphene. The nitrogen-doped carbon is uniformly dispersed on the nanocables. As anode materials for Li-ion batteries, the TiO2/C composites exhibit excellent rate capability and cycling stability. A capacity of 150 mAh/g is retained at a current density of 4 A/g. The enhanced electrochemical performance may be attributed to the well-dispersed carbon conductive framework, which facilitates charge transfer during the lithium insertion/extraction process.

  7. Synthesis of highly stable sub-8 nm TiO2 nanoparticles and their multilayer electrodes of TiO2/MWNT for electrochemical applications.

    PubMed

    Hyder, Md Nasim; Gallant, Betar M; Shah, Nisarg J; Shao-Horn, Yang; Hammond, Paula T

    2013-10-09

    Next-generation electrochemical energy storage for integrated microsystems and consumer electronic devices requires novel electrode materials with engineered architectures to meet the requirements of high performance, low cost, and robustness. However, conventional electrode fabrication processes such as doctor blading afford limited control over the electrode thickness and structure at the nanoscale and require the incorporation of insulating binder and other additives, which can promote agglomeration and reduce active surface area, limiting the inherent advantages attainable from nanoscale materials. We have engineered a route for the synthesis of highly stable, sub-8 nm TiO2 nanoparticles and their subsequent incorporation with acid-functionalized multiwalled carbon nanotubes (MWNTs) into nanostructured electrodes using aqueous-based layer-by-layer electrostatic self-assembly. Using this approach, binder-free thin film electrodes with highly controllable thicknesses up to the micrometer scale were developed with well-dispersed, nonagglomerated TiO2 nanoparticles on MWNTs. Upon testing in an Li electrochemical half-cell, these electrodes demonstrate high capacity (>150 mAh/gel(ectrode) at 0.1 A/gel(ectrode)), good rate capability (>100 mAh/gel(ectrode) up to 1 A/g(electrode)) and nearly no capacity loss up to 200 cycles for electrodes with thicknesses up to 1480 nm, indicating their promise as thin-film negative electrodes for future Li storage applications.

  8. Engineering of highly ordered TiO2 nanopore arrays by anodization

    NASA Astrophysics Data System (ADS)

    Wang, Huijie; Huang, Zhennan; Zhang, Li; Ding, Jie; Ma, Zhaoxia; Liu, Yong; Kou, Shengzhong; Yang, Hangsheng

    2016-07-01

    Finite element analysis was used to simulate the current density distributions in the TiO2 barrier layer formed at the initial stage of Ti anodization. The morphology modification of the barrier layer was found to induce current density distribution change. By starting the anodization with proper TiO2 barrier layer morphology, the current density distribution can be adjusted to favor the formation of either nanotube arrays or nanopore arrays of anodic TiO2. We also found that the addition of sodium acetate into the electrolyte suppressed both the field-assisted chemical dissolution of TiO2 and the TiF62- hydrolysis induced TiO2 deposition during anodization, and thus further favored the nanopore formation. Accordingly, highly ordered anodic TiO2 nanopore arrays, similar to anodic aluminum oxide nanopore arrays, were successfully prepared.

  9. Review of the progress in preparing nano TiO2: an important environmental engineering material.

    PubMed

    Wang, Yan; He, Yiming; Lai, Qinghua; Fan, Maohong

    2014-11-01

    TiO2 nanomaterial is promising with its high potential and outstanding performance in photocatalytic environmental applications, such as CO2 conversion, water treatment, and air quality control. For many of these applications, the particle size, crystal structure and phase, porosity, and surface area influence the activity of TiO2 dramatically. TiO2 nanomaterials with special structures and morphologies, such as nanospheres, nanowires, nanotubes, nanorods, and nanoflowers are thus synthesized due to their desired characteristics. With an emphasis on the different morphologies of TiO2 and the influence factors in the synthesis, this review summarizes fourteen TiO2 preparation methods, such as the sol-gel method, solvothermal method, and reverse micelle method. The TiO2 formation mechanisms, the advantages and disadvantages of the preparation methods, and the photocatalytic environmental application examples are proposed as well.

  10. Comparison study on photocatalytic oxidation of pharmaceuticals by TiO2-Fe and TiO2-reduced graphene oxide nanocomposites immobilized on optical fibers.

    PubMed

    Lin, Lu; Wang, Huiyao; Jiang, Wenbin; Mkaouar, Ahmed Radhi; Xu, Pei

    2017-03-08

    Incorporating reduced graphene oxide (rGO) or Fe(3+) ions in TiO2 photocatalyst could enhance photocatalytic degradation of organic contaminants in aqueous solutions. This study characterized the photocatalytic activities of TiO2-Fe and TiO2-rGO nanocomposites immobilized on optical fibers synthesized by polymer assisted hydrothermal deposition method. The photocatalysts presented a mixture phase of anatase and rutile in the TiO2-rGO and TiO2-Fe nanocomposites. Doping Fe into TiO2 particles (2.40eV) could reduce more band gap energy than incorporating rGO (2.85eV), thereby enhancing utilization efficiency of visible light. Incorporating Fe and rGO in TiO2 decreased significantly the intensity of TiO2 photoluminescence signals and enhanced the separation rate of photo-induced charge carriers. Photocatalytic performance of the synthesized nanocomposites was measured by the degradation of three pharmaceuticals under UV and visible light irradiation, including carbamazepine, ibuprofen, and sulfamethoxazole. TiO2-rGO exhibited higher photocatalytic activity for the degradation of pharmaceuticals under UV irradiation, while TiO2-Fe demonstrated more suitable for visible light oxidation. The results suggested that the enhanced photocatalytic performance of TiO2-rGO could be attributed to reduced recombination rate of photoexcited electrons-hole pairs, but for TiO2-Fe nanocomposite, narrower band gap would contribute to increased photocatalytic activity.

  11. Conversion of Nanocellulose Aerogel into TiO2 and TiO2@C Nano-thorns by Direct Anhydrous Mineralization with TiCl4. Evaluation of Electrochemical Properties in Li Batteries.

    PubMed

    Henry, Aurélien; Plumejeau, Sandrine; Heux, Laurent; Louvain, Nicolas; Monconduit, Laure; Stievano, Lorenzo; Boury, Bruno

    2015-07-15

    Nanostructured TiO2 and TiO2@C nanocomposites were prepared by an original process combining biotemplating and mineralization of aerogels of nanofibrillated cellulose (NFC). A direct one step treatment of NFC with TiCl4 in strictly anhydrous conditions allows TiO2 formation at the outermost part of the nanofibrils while preserving their shape and size. Such TiO2@cellulose composites can be transformed into TiO2 nanotubes (TiO2-NT) by calcination in air at 600 and 900 °C, or into TiO2@C nanocomposites by pyrolysis in argon at 600 and 900 °C. Detailed characterization of these materials is reported here, along with an assessment of their performance as negative electrode materials for Li-ion batteries.

  12. Controlled preparation of porous TiO2-Ag nanostructures through supramolecular assembly for plasmon-enhanced photocatalysis.

    PubMed

    Fei, Jinbo; Li, Junbai

    2015-01-14

    By templating Ag(+)-induced supramolecular assembly at different temperatures, porous TiO2-Ag nanotubes and nanospheres are fabricated in a controlled manner due to the effect of Rayleigh instability. Compared with traditional TiO2 nanoparticles, TiO2-Ag nanostructures above show much more extensive visible light absorption and exhibit the noticeably plasmon-enhanced photocatalysis because of the existence of Ag nanoparticles.

  13. Nanofibrous TiO2 improving performance of mesoporous TiO2 electrode in dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Zukalová, Markéta; Kavan, Ladislav; Procházka, Jan; Zukal, Arnošt; Yum, Jun-Ho; Graetzel, Michael

    2013-05-01

    A method of direct coating of conducting glass by electrospinning was developed. Electrospun fibrous TiO2 consisting of closely packed anatase nanocrystals of 40-50 nm in size was incorporated into mesoporous TiO2 thin film stabilized by phosphorus. The mesoporous framework formed by walls with 5-6 nm TiO2 nanocrystals surrounding 20 nm mesopores exhibits extreme porosity and consequently limited number of necking points. TiO2 with fibrous morphology was found to solidify mesoporous titania and to be beneficial for the performance of corresponding photoanode in dye-sensitized solar cell (DSC). Obviously, its wire-like structure suitably interconnects mesoporous network and thus increases the electron collection efficiency from the TiO2 layer to the F-doped SnO2 electrode. The solar conversion efficiency of a DSC employing optimized photoanode consisting of nanocrystalline fibrous bottom layer, four mesoporous layers, and one nanocrystalline anatase scattering top layer sensitized with the N945 dye reached 5.35 %. This represents an improvement of about 9 % compared to the solar conversion efficiency of a DSC employing purely mesoporous TiO2 layer prepared by means of phosphorus doping (5.05 %).

  14. Enhanced photocatalytic activity towards degradation and H2 evolution over one dimensional TiO2@MWCNTs heterojunction

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao; Cao, Shuang; Wu, Zhijiao; Zhao, Suling; Piao, Lingyu

    2017-04-01

    With the distinct electronic and optical properties, multiwall carbon nanotubes (MWCNTs) are identified as an outstanding catalyst support, which can effectively improve the performance of the TiO2 photocatalysts. Herein, the unique one dimensional TiO2@MWCNTs nanocomposites have been prepared by a facile hydrothermal method. The TiO2 coating layers are extremely uniform and the thickness is adjustable for different nanocomposites. XPS measurements confirm that intimate electronic interactions are existed between MWCNTs and TiO2 via interfacial Tisbnd Osbnd C bond and the photoluminescence intensity of the TiO2@MWCNTs nanocomposites are effectively quenched compared with pure TiO2, suggesting the fast electron transfer rates. The thickness of TiO2 coating layers of the TiO2@MWCNTs nanocomposites plays a significant role in the photocatalytic degradation of organic pollutants, such as methylene blue (MB) and Rhodamine B (RhB), and photocatalytic H2 evolution from water. Due to the formation of one dimensional heterojunction of TiO2@MWCNTs nanocomposites and the positive synergistic effect between TiO2 and carbon nanotubes, it is found that the photocatalytic activity of the system is significantly improved.

  15. Lithium insertion in nanostructured TiO(2)(B) architectures.

    PubMed

    Dylla, Anthony G; Henkelman, Graeme; Stevenson, Keith J

    2013-05-21

    (+) pathways from surface to subsurface sites, which many chemists believe to contribute to the pseudocapacitive charging. Several disadvantages exist as well. TiO2(B), and titania in general, suffers from poor electronic and ionic conductivity. Nanostructured TiO2(B) also exhibits significant irreversible capacity loss (ICL) upon first discharge (lithiation). Nanostructuring TiO2(B) can help alleviate problems with poor ionic conductivity by shortening lithium diffusion pathways. Unfortunately, this also increases the likelihood of severe first discharge ICL due to reactive Ti-OH and Ti-O surface sites that can cause unwanted electrolyte degradation and irreversible trapping of Li(+). Nanostructuring also results in lowered volumetric energy density, which could be a considerable problem for mobile applications. We will also discuss these problems and proposed solutions. Scientists have synthesized TiO2(B) in a variety of nanostructures including nanowires, nanotubes, nanoparticles, mesoporous-ordered nanostructures, and nanosheets. Many of these structures exhibit enhanced Li(+) diffusion kinetics and increased specific capacities compared to bulk material, and thus warrant investigation on how nanostructuring influences lithiation behavior. This Account will focus on these influences from both experimental and theoretical perspectives. We will discuss the surface charging mechanism that gives rise to the increased lithiation and delithiation kinetics for TiO2(B), along with the influence of dimensional confinement of the nanoarchitectures, and how nanostructuring can change the lithiation mechanism considerably.

  16. Photocatalytic oxidation of propylene on La and N codoped TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Liu, Jinfeng; Li, Haiyan; Zong, Lanlan; Li, Qiuye; Wang, Xiaodong; Zhang, Min; Yang, Jianjun

    2015-02-01

    Lanthanum- and nitrogen-codoped TiO2 photocatalysts was synthesized using orthorhombic nanotubes titanic acid as the precursor by a simple impregnation and subsequent calcination method. The morphology, phase structure, and properties of La- and N-codoped TiO2 were well characterized by transmission electron microscopy, X-ray diffraction, Raman spectra, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectra. The La-/N-codoped TiO2 showed excellent photoactivity of propylene oxidation compared with the single-doped TiO2 and La-/N-codoped P25 TiO2 nanoparticles under visible light irradiation. The origin of the enhancement of the visible light-responsive photocatalytic activity was discussed in detail.

  17. Hydrogen Impurity Defects in Rutile TiO2

    PubMed Central

    Mo, Li-Bin; Wang, Yu; Bai, Yang; Xiang, Qing-Yun; Li, Qun; Yao, Wen-Qing; Wang, Jia-Ou; Ibrahim, Kurash; Wang, Huan-Hua; Wan, Cai-Hua; Cao, Jiang-Li

    2015-01-01

    Hydrogen-related defects play crucial roles in determining physical properties of their host oxides. In this work, we report our systematic experimental and theoretical (based on density functional theory) studies of the defect states formed in hydrogenated-rutile TiO2 in gaseous H2 and atomic H. In gas-hydrogenated TiO2, the incorporated hydrogen tends to occupy the oxygen vacancy site and negatively charged. The incorporated hydrogen takes the interstitial position in atom-hydrogenated TiO2, forming a weak O-H bond with the closest oxygen ion, and becomes positive. Both states of hydrogen affect the electronic structure of TiO2 mainly through changes of Ti 3d and O 2p states instead of the direct contributions of hydrogen. The resulted electronic structures of the hydrogenated TiO2 are manifested in modifications of the electrical and optical properties that will be useful for the design of new materials capable for green energy economy. PMID:26627134

  18. New generation fiber reinforced polymer composites incorporating carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Soliman, Eslam

    The last five decades observed an increasing use of fiber reinforced polymer (FRP) composites as alternative construction materials for aerospace and infrastructure. The high specific strength of FRP attracted its use as non-corrosive reinforcement. However, FRP materials were characterized with a relatively low ductility and low shear strength compared with steel reinforcement. On the other hand, carbon nanotubes (CNTs) have been introduced in the last decade as a material with minimal defect that is capable of increasing the mechanical properties of polymer matrices. This dissertation reports experimental investigations on the use of multi-walled carbon nanotubes (MWCNTs) to produce a new generation of FRP composites. The experiments showed significant improvements in the flexure properties of the nanocomposite when functionalized MWCNTs were used. In addition, MWCNTs were used to produce FRP composites in order to examine static, dynamic, and creep behavior. The MWCNTs improved the off-axis tension, off-axis flexure, FRP lap shear joint responses. In addition, they reduced the creep of FRP-concrete interface, enhanced the fracture toughness, and altered the impact resistance significantly. In general, the MWCNTs are found to affect the behaviour of the FRP composites when matrix failure dominates the behaviour. The improvement in the mechanical response with the addition of low contents of MWCNTs would benefit many industrial and military applications such as strengthening structures using FRP composites, composite pipelines, aircrafts, and armoured vehicles.

  19. Effect of TiO2 pigment gradation on the properties of thermal insulation coatings

    NASA Astrophysics Data System (ADS)

    Shen, Lu-wei; Zhang, Ya-mei; Zhang, Pei-gen; Shi, Jin-jie; Sun, Zheng-ming

    2016-12-01

    This study was designed to evaluate the thermal performance and mechanical properties of coatings with different gradations of TiO2 pigments. The solar reflectance, cooling performance, wash resistance, and film adhesion strength of the coatings were investigated. The influence of TiO2 powder gradation on the final properties of the coatings was studed. The solar reflectance and the thermal insulation were observed to increase with increasing content of nanosized TiO2. The mechanical properties of the coatings, such as their wash resistance and film adhesion strength, were observed to increase with increased incorporation of nanosized TiO2. Such improvements in the properties of the coatings were attributed to the greater specific surface area and lower thermal conductivity of nanosized TiO2 particles compared to normal TiO2 particles.

  20. Location Of Hole And Electron Traps On Nanocrystalline Anatase TiO2

    SciTech Connect

    Mercado, Candy C.; Knorr, Fritz J.; McHale, Jeanne L.; Usmani, Shirin M.; Ichimura, Andrew S.; Saraf, Laxmikant V.

    2012-05-17

    The defect photoluminescence from TiO2 nanoparticles in the anatase phase is reported for nanosheets which expose predominantly (001) surfaces, and compared to that from conventional anatase nanoparticles which expose mostly (101) surfaces. Also reported is the weak defect photoluminescence of TiO2 nanotubes, which we find using electron back-scattered diffraction to consist of walls which expose (110) and (100) facets. The nanotubes exhibit photoluminescence that is blue-shifted and much weaker than that from conventional TiO2 nanoparticles. Despite the preponderance of (001) surfaces in the nanosheet samples, they exhibit photoluminescence similar to that of conventional nanoparticles. We assign the broad visible photoluminescence of anatase nanoparticles to two overlapping distributions: hole trap emission associated with oxygen vacancies on (101) exposed surfaces, which peaks in the green, and a broader emission extending into the red which results from electron traps on under-coordinated titanium atoms, which are prevalent on (001) facets. The results of this study suggest how morphology of TiO2 nanoparticles could be optimized to control the distribution and activity of surface traps. Our results also shed light on the mechanism by which the TiCl4 surface treatment heals traps on anatase and mixed-phase TiO2 films, and reveals distinct differences in the trap-state distributions of TiO2 nanoparticles and nanotubes. The molecular basis for electron and hole traps and their spatial separation on different facets is discussed.

  1. Enhancement in photo-induced hydrophilicity of TiO2/CNT nanostructures by applying voltage

    NASA Astrophysics Data System (ADS)

    Abdi, Yaser; Khalilian, Maryam; Arzi, Ezatollah

    2011-06-01

    Carbon nanotube (CNT) arrays were synthesized by plasma-enhanced chemical vapour deposition on a silicon substrate. Cabbage-like TiO2 nanostructures on the CNTs were produced by atmospheric-pressure chemical vapour deposition. Scanning electron microcopy was used to study the morphology of the TiO2/CNT structures while x-ray diffraction and Fourier transform infrared (FTIR) spectroscopy were used to verify the characteristics of the prepared nanostructures. Their hydrophilicity under UV and visible light was investigated and compared with the activity of thin films of TiO2. The TiO2/CNTs showed a highly improved photocatalytic activity in comparison with the TiO2 film. The excellent visible-light-induced hydrophilicity of the TiO2/CNTs was attributed to the generation of electron-hole pairs by visible light excitation with a low recombination rate. The results of this study showed that the fabricated cabbage-like TiO2/CNT nanostructures have a super-hydrophilic surface without further UV irradiation. Electrical measurements showed that a p-n junction was formed at the interface of the TiO2/CNTs. Consequently, a super-hydrophilic surface was achieved by applying an electric bias voltage. Visible-light- and electro-induced hydrophilicity of the obtained nanostructure was reported in this work.

  2. Photocatalytic oxidation of selected gas-phase VOCs using UV light, TiO2, and TiO2/Pd.

    PubMed

    Fujimoto, Tânia M; Ponczek, Milena; Rochetto, Ursula L; Landers, Richard; Tomaz, Edson

    2016-03-30

    Heterogeneous photocatalytic oxidation systems using titanium dioxide (TiO2) have been extensively studied for the removal of several volatile organic compounds (VOCs). The addition of noble metals such as palladium on TiO2 may improve photocatalytic activity by increasing charge separation efficiency. In this work, palladium was impregnated on TiO2 and the efficiency of the new catalyst was tested and compared with that of pure TiO2. Pd was impregnated on TiO2 by the reduction method, using NaBH4, and was characterized by XRD, XPS, UV-Vis, and H2 chemisorption. The photocatalytic tests were performed in an annular coated-wall reactor using octane, isooctane, n-hexane, and cyclohexane at inlet concentrations varying from 100 to 120 ppmv. Compared with pure TiO2 film, the photocatalytic activity of TiO2 impregnated with 1 wt% of palladium was improved. All the aforementioned analytical techniques confirmed the presence of Pd incorporated into the structure of TiO2, and the conversion rates were studied in a broad range of residence times, yielding up to 90 % or higher rates in 40 s of residence time, thus underscoring the relevant contribution of the technology.

  3. Biocompatibility of different nanostructured TiO2 scaffolds and their potential for urologic applications.

    PubMed

    Imani, Roghayeh; Pazoki, Meysam; Zupančič, Daša; Kreft, Mateja Erdani; Kralj-Iglič, Veronika; Veranič, Peter; Iglič, Aleš

    2016-11-01

    Despite great efforts in tissue engineering of the ureter, urinary bladder, and urethra, further research is needed in order to improve the patient's quality of life and minimize the economic burden of different lower urinary tract disorders. The nanostructured titanium dioxide (TiO2) scaffolds have a wide range of clinical applications and are already widely used in orthopedic or dental medicine. The current study was conducted to synthesize TiO2 nanotubes by the anodization method and TiO2 nanowires and nanospheres by the chemical vapor deposition method. These scaffolds were characterized with scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods. In order to test the urologic applicability of generated TiO2 scaffolds, we seeded the normal porcine urothelial (NPU) cells on TiO2 nanotubes, TiO2 nanowires, TiO2 nanospheres, and on the standard porous membrane. The viability and growth of the cells were monitored everyday, and after 3 weeks of culturing, the analysis with scanning electron microscope (SEM) was performed. Our results showed that the NPU cells were attached on all scaffolds; they were viable and formed a multilayered epithelium, i.e., urothelium. The apical plasma membrane of the majority of superficial NPU cells, grown on all three different TiO2 scaffolds and on the porous membrane, exhibited microvilli; thus, indicating that they were at a similar differentiation stage. The maximal caliper diameter measurements of superficial NPU cells revealed significant alterations, with the largest cells being observed on nanowires and the smallest ones on the porous membrane. Our findings indicate that different nanostructured TiO2 scaffolds, especially nanowires, have a great potential for tissue engineering and should be further investigated for various urologic applications.

  4. Influence of TiO2 nanostructures on the optical absorption of organic-inorganic perovskite

    NASA Astrophysics Data System (ADS)

    Liu, Zongyi; Ye, Mao; Ostrowski, Michel; Yi, Ya Sha

    2016-04-01

    This work aims to reveal the strong influence of TiO2 nanostructures on the light absorption property of TiO2 and perovskite mixture. Three TiO2 nanostructures, i.e., nanoparticles (S1), ultrapure nanorods (S2), and ultrasmall nanorods (S3), were studied: S1 was selected as a baseline; S2 and S3 were synthesized from S1 by using modified hydrothermal processes. Mesoporous TiO2 thin films were spin-coated from solutions containing these TiO2 nanorods and nanoparticles (S1 as baseline). Organic-inorganic hybrid perovskite CH3NH3PbI3 was then incorporated into these mesoporous TiO2 thin films. Optical absorption results showed that the perovskite mixture with ultrasmall TiO2 nanostructures (S3) has significantly higher optical absorption coefficient. Finite-difference time domain models were built based on three distinct nanostructures of TiO2 and CH3NH3PbI3 mixtures fabricated (S1 to S3) to understand their optical absorption properties. Our work is promising to fabricate TiO2 nanostructures, as a backbone structure, for a series of applications including photovoltaics and photodetection.

  5. Improved performance of lithium ion battery separator enabled by co-electrospinnig polyimide/poly(vinylidene fluoride-co-hexafluoropropylene) and the incorporation of TiO2-(2-hydroxyethyl methacrylate)

    NASA Astrophysics Data System (ADS)

    Chen, Weiya; Liu, Yanbo; Ma, Ying; Yang, Wenxiu

    2015-01-01

    Functionalized TiO2 (f-TiO2) was synthesized by the atom transfer radical polymerization process and then three types of composite nanofiber membranes including PI/PVdF-HFP (PI/PH, with no nanoparticles contained in PI), TiO2@PI/PVdF-HFP (T@PI/PH, with TiO2 mixed in PI) and f-TiO2@PI/PVdF-HFP (f-T@PI/PH, with f-TiO2 blended in PI) were prepared by bicomponent co-electrospinning technique which could separately maintain the original properties of both PVdF-HFP and PI nanofibers. UV-vis characterization manifested that the modified nanoparticles can provide significant improvements in reducing the particle agglomeration. Morphology, porosity, electrolyte uptake and liquid electrolyte contact angle of all the electrospun separators were investigated, and results showed that the composite separator with 2% f-TiO2 nanoparticle had smaller fiber diameter, higher porosity, larger electrolyte uptake, smaller contact angle and more excellent thermal dimensional stability. More importantly, the tensile strength of all the composite membranes increased by more than three times after thermal calendering process, which resulted from the several bonded points caused by the fusion of PVdF-HFP component with low melting temperature. Additionally, electrochemical properties of PI/PH, 2% T@PI/PH and 2% f-T@PI/PH composite separators and cycling performances of corresponding batteries were evaluated and 2% f-T@PI/PH composite separator showed better properties than the other two.

  6. Eco-friendly synthesis of TiO2, Au and Pt doped TiO2 nanoparticles for dye sensitized solar cell applications and evaluation of toxicity

    NASA Astrophysics Data System (ADS)

    Gopinath, K.; Kumaraguru, S.; Bhakyaraj, K.; Thirumal, S.; Arumugam, A.

    2016-04-01

    Driven by the demand of pure TiO2, Au and Pt doped TiO2 NPs were successfully synthesized using Terminalia arjuna bark extract. The eco-friendly synthesized NPs were characterized by UV-Vis-DRS, ATR-FT-IR, PL, XRD, Raman, SEM with EDX and TEM analysis. The synthesized NPs were investigation for dye sensitized solar cell applications. UV-Vis-Diffused Reflectance Spectra clearly showed that the expected TiO2 inter band absorption below 306 nm, incorporation of gold shows surface plasma resonant (SPR) near 555 nm and platinum incorporated TiO2 NPs shows absorbance at 460 nm. The energy conversion efficiency for Au doped TiO2 NPs when compared to pure and Pt doped TiO2 NPs. In addition to that, Au noble metal present TiO2 matrix and an improve open-circuit voltage (Voc) of DSSC. Synthesized NPs was evaluated into antibacterial and antifungal activities by disk diffusion method. It is observed that NPs have not shown any activities in all tested bacterial and fungal strains. In this eco-friendly synthesis method to provide non toxic and environmental friendly nanomaterials can be used for solar energy device application.

  7. Panchromatic Sensitizer for Dye-Sensitized Solar Cells: Unsymmetrical Squaraine Dyes Incorporating Benzodithiophene π-Spacer with Alkyl Chains to Extend Conjugation, Control the Dye Assembly on TiO2, and Retard Charge Recombination.

    PubMed

    Bisht, Rajesh; M K, Munavvar Fairoos; Singh, Ambarish Kumar; Nithyanandhan, Jayaraj

    2017-02-17

    Metal-free near-infrared (NIR) active unsymmetrical squaraine dyes, RSQ1 and RSQ2, with benzodithiophene (BDT) π-spacer and cyanoacrylic acid acceptor were synthesized by utilizing palladium catalyzed direct (hetero)arylation reaction. Methyl and 2-ethylhexyl groups were strategically placed at the BDT unit for RSQ1 and RSQ2, respectively, to investigate the effect of alkylated π-spacer on dye aggregation on the TiO2 surface and recombination reactions at TiO2/dye/electrolyte interface. These dyes have strong absorption (ε > 10(5) M(-1) cm(-1)) in near-infrared (NIR) region and exhibit similar optical and electrochemical properties as they have same conjugated framework. RSQ2 performed better than RSQ1 owing to its higher open-circuit voltage (Voc) and fill factor (ff) in spite of having comparable short-circuit current density (Jsc). The panchromatic incident photon-to-current conversion efficiency (IPCE) response was also observed for both the dyes. RSQ2 showed power conversion efficiency (PCE) of 6.72% with short-circuit current density (Jsc) of 18.53 mA/cm(2), open circuit voltage (Voc) of 0.538 V, and fill factor (ff) of 67.4%, without any coadsorbent. Attenuation of the charge recombination for RSQ2 was revealed by electrochemical impedance analysis (EIS) and open-circuit potential decay transients (OCVD), which attributes to its higher Voc and ff in comparison to RSQ1.

  8. Controllable atomic layer deposition of one-dimensional nanotubular TiO2

    NASA Astrophysics Data System (ADS)

    Meng, Xiangbo; Banis, Mohammad Norouzi; Geng, Dongsheng; Li, Xifei; Zhang, Yong; Li, Ruying; Abou-Rachid, Hakima; Sun, Xueliang

    2013-02-01

    This study aimed at synthesizing one-dimensional (1D) nanostructures of TiO2 using atomic layer deposition (ALD) on anodic aluminum oxide (AAO) templates and carbon nanotubes (CNTs). The precursors used are titanium tetraisopropoxide (TTIP, Ti(OCH(CH3)2)4) and deionized water. It was found that the morphologies and structural phases of as-deposited TiO2 are controllable through adjusting cycling numbers of ALD and growth temperatures. Commonly, a low temperature (150 °C) produced amorphous TiO2 while a high temperature (250 °C) led to crystalline anatase TiO2 on both AAO and CNTs. In addition, it was revealed that the deposition of TiO2 is also subject to the influences of the applied substrates. The work well demonstrated that ALD is a precise route to synthesize 1D nanostructures of TiO2. The resultant nanostructured TiO2 can be important candidates in many applications, such as water splitting, solar cells, lithium-ion batteries, and gas sensors.

  9. Hierarchical Oriented Anatase TiO2 Nanostructure arrays on Flexible Substrate for Efficient Dye-sensitized Solar Cells

    PubMed Central

    Wu, Wu-Qiang; Rao, Hua-Shang; Xu, Yang-Fan; Wang, Yu-Fen; Su, Cheng-Yong; Kuang, Dai-Bin

    2013-01-01

    The vertically oriented anatase single crystalline TiO2 nanostructure arrays (TNAs) consisting of TiO2 truncated octahedrons with exposed {001} facets or hierarchical TiO2 nanotubes (HNTs) consisting of numerous nanocrystals on Ti-foil substrate were synthesized via a two-step hydrothermal growth process. The first step hydrothermal reaction of Ti foil and NaOH leads to the formation of H-titanate nanowire arrays, which is further performed the second step hydrothermal reaction to obtain the oriented anatase single crystalline TiO2 nanostructures such as TiO2 nanoarrays assembly with truncated octahedral TiO2 nanocrystals in the presence of NH4F aqueous or hierarchical TiO2 nanotubes with walls made of nanocrystals in the presence of pure water. Subsequently, these TiO2 nanostructures were utilized to produce dye-sensitized solar cells in a backside illumination pattern, yielding a significant high power conversion efficiency (PCE) of 4.66% (TNAs, JSC = 7.46 mA cm−2, VOC = 839 mV, FF = 0.75) and 5.84% (HNTs, JSC = 10.02 mA cm−2, VOC = 817 mV, FF = 0.72), respectively. PMID:23715529

  10. Transport properties in single-crystalline rutile TiO2 nanorods

    NASA Astrophysics Data System (ADS)

    Chen, R. S.; Chen, C. A.; Wang, W. C.; Tsai, H. Y.; Huang, Y. S.

    2011-11-01

    Electronic transport properties of the single-crystalline titanium dioxide (TiO2) nanorods (NRs) with single rutile phase have been investigated. The conductivity values for the individual TiO2 NRs grown by metal-organic chemical vapor deposition are in the range of 1-10 Ω-1 cm-1. The temperature-dependent measurement shows the presence of two shallow donor levels/bands with activation energies at 8 and 28 meV, respectively. On the photoconductivity (PC), the TiO2 NRs exhibit the much higher normalized PC gain and sensitive excitation-power dependence than the polycrystalline nanotubes. The results demonstrate the superior photoconduction efficiency and distinct mechanism in the monocrystalline one-dimensional TiO2 nanostructures in comparison to the polycrystalline or nanoporous counterparts.

  11. Effect of fluorine doped TiO2 on the property of perovskite solar cell

    NASA Astrophysics Data System (ADS)

    Zhang, X. Q.; Wu, Y. P.; Huang, Y.; Zhou, Z. H.; Shen, S.

    2017-03-01

    Anatase TiO2 nanoparticles with different amounts of fluorine doping were synthesized by a hydrothermal method using hydrogen titanate nanotubes as a precursor and applied as mesoporous layer for preparing perovskite solar cell. The morphology and structures were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD), meanwhile, the properties and performances were tested by photoluminescence spectrum (PL) and current density and voltage (J-V) curve. It was found that doping fluorine into TiO2 made the photoelectric conversion efficiency (PCE) of perovskite solar cell (PSC) to be improved. The best PCE of PSC based on a F-doped TiO2 was 13.06% and increased by 51% compared to an un-doped TiO2. The study provided a direction for the exploration of high performance electron transport layer of perovskite solar cell.

  12. Preparation, characterization and photocatalytic activities of TiO2-SrTiO3 composites

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Zhu, Lianjie; Gao, Fubo; Xie, Hanjie

    2017-01-01

    Series of TiO2-SrTiO3 composites were synthesized by hydrothermal method, using TiO2 nanotube array as a precursor and Sr(OH)2 as a Sr source material. TiO2-SrTiO3 products with various composition were obtained by simply changing the reaction time. The as-synthesized products were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The optical properties were studied by means of UV-Vis absorption spectroscopy and photoluminescence (PL) spectra. Their photocatalytic activities were assessed by photodegradation of rhodamine B (RhB) solution and the photocatalytic reaction mechanism was discussed. The TiO2-SrTiO3 composites obtained at 2 h exhibits the highest activity for photodegradation of RhB.

  13. Ultraviolet and Visible Photochemistry of Methanol at 3D Mesoporous Networks: TiO2 and Au-TiO2

    DTIC Science & Technology

    2013-05-23

    Y. Titania Aerogels as a Superior Mesoporous Structure for Photoanodes of Dye-Sensitized Solar Cells . Int. J. Electrochem. Sci. 2012, 7, 6910−6919...methanol photochemistry at three-dimensionally (3D) networked aerogels of TiO2 or Au– TiO2 reveals that incorporated Au nanoparticles strongly sensitize...the oxide nanoarchitecture to visible light. Methanol dissociatively adsorbs at the surfaces of TiO2 and Au– TiO2 aerogels under dark, high-vacuum

  14. Mechanochemical Synthesis of TiO2 Nanocomposites as Photocatalysts for Benzyl Alcohol Photo-Oxidation

    PubMed Central

    Ouyang, Weiyi; Kuna, Ewelina; Yepez, Alfonso; Balu, Alina M.; Romero, Antonio A.; Colmenares, Juan Carlos; Luque, Rafael

    2016-01-01

    TiO2 (anatase phase) has excellent photocatalytic performance and different methods have been reported to overcome its main limitation of high band gap energy. In this work, TiO2-magnetically-separable nanocomposites (MAGSNC) photocatalysts with different TiO2 loading were synthesized using a simple one-pot mechanochemical method. Photocatalysts were characterized by a number of techniques and their photocatalytic activity was tested in the selective oxidation of benzyl alcohol to benzaldehyde. Extension of light absorption into the visible region was achieved upon titania incorporation. Results indicated that the photocatalytic activity increased with TiO2 loading on the catalysts, with moderate conversion (20%) at high benzaldehyde selectivity (84%) achieved for 5% TiO2-MAGSNC. These findings pointed out a potential strategy for the valorization of lignocellulosic-based biomass under visible light irradiation using designer photocatalytic nanomaterials. PMID:28335221

  15. UV protection afforded by gel-trapped TiO2 particles.

    PubMed

    Sojka, Milan F; Cummins, Phillip G; Declercq, Lieve A G; Fthenakis, Christina G; Ionita-Manzatu, Mirela C; Lee, Wilson A; Maes, Daniel H; McKeever-Alfieri, Mary Ann; Najdek, Linda J; Pernodet, Nadine; Sente, Ilse M E; Teta, Lawrence P; Van Rillaer, Katrin; Yarosh, Daniel B; Giacomoni, Paolo U

    2011-07-01

    We have developed a technology to incorporate micronized titanium dioxide (TiO(2)), together with antioxidants, in particles of a UV-visible transparent polymer gel. These particles are coated with silica to avoid clustering and the size of the micronized TiO(2) reduces the back scattering of white light. gel-trapped TiO(2) minimizes the oxidative stress exerted by UV radiation, increases the photo-stability of some accompanying ingredients, such as avobenzone. The size of the particles is in the micrometre range. This favors their permanence on the top of the stratum corneum. Gel-trapped TiO(2)-based sunscreens provide a larger SPF and two-fold larger UVA protection than equal-composition sunscreens that contain larger amounts of untrapped TiO(2).

  16. Superhydrophobic surface of TiO2 hierarchical nanostructures fabricated by Ti anodization.

    PubMed

    Dong, Junye; Ouyang, Xin; Han, Jie; Qiu, Wei; Gao, Wei

    2014-04-15

    A hierarchical structure of TiO2 with disordered nanowires on top of regular nanotubes was fabricated. With organic monolayers, it showed stronger superhydrophobic properties than regular nanotubes. The surface roughness was further enhanced by removing the dense nanowires layer, resulting in 172° water contact angle. The potential application for aquatic devices was explored by the treated Ti mesh which showed striking floating stability.

  17. Dispersions of geometric TiO2 nanomaterials and their toxicity to RPMI 2650 nasal epithelial cells

    NASA Astrophysics Data System (ADS)

    Tilly, Trevor B.; Kerr, Lei L.; Braydich-Stolle, Laura K.; Schlager, John J.; Hussain, Saber M.

    2014-11-01

    Titanium dioxide (TiO2) based nanofilaments—nanotube, nanowire, nanorod—have gained interest for industrial, electrical, and as of recent, medical applications due to their superior performance over TiO2 nanoparticles. Safety assessment of these nanomaterials is critical to protect workers, patients, and bystanders as these technologies become widely implemented. Additionally, TiO2 based nanofilaments can easily be inhaled by humans and their high aspect ratio, much like asbestos fibers, may make them toxic in the respiratory system. The tendency of TiO2 nanofilaments to aggregate makes evaluating their nanotoxicity difficult and the results controversial, because incomplete dispersion results in larger particle sizes that are no longer in the nano dimensional size range. TiO2 nanofilaments are aggregated and difficult to disperse homogeneously in solution by conventional methods, such as sonication and vortexing. In this study, a microfluidic device was utilized to produce stable, homogeneous dosing solutions necessary for in vitro toxicity evaluation by eliminating any toxicity caused by aggregated TiO2 nanomaterials. The toxicity results could then be directly correlated to the TiO2 nanostructure itself. The toxicity of four TiO2 nanogeometries—nanotube, nanowire, nanorod, and nanoparticle—were assessed in RPMI 2650 human nasal epithelial cells at representative day, week, and month in vitro exposure dosages of 10, 50, 100 μg/ml, respectively. All TiO2 based nanomaterials dispersed by the microfluidic method were nontoxic to RPMI 2650 cells at the concentrations tested, whereas higher concentrations of 100 μg/ml of nanowires and nanotubes dispersed by sonication reduced viability up to 27 %, indicating that in vitro toxicity results may be controlled by the dispersion of dosing solutions.

  18. Effects of TiO2 structures in dye-sensitized solar cell.

    PubMed

    Kim, Bok-Min; Rho, Seon-Gyun; Kang, Choon-Hyoung

    2011-02-01

    In this work, the effects of crystalline structure of the TiO2, which is incorporated in fabrication of the n-type electrode, on the DSSC performance were investigated in terms of the energy conversion efficiency. In this effort, TiO2 nanoparticle pastes with varying contents of rutile and anatase structures were prepared by using the ethanol mixing method. The most efficient photo-electro-chemical performance was achieved for the DSSC fabricated with the TiO2 paste in which the anatase form of the nanocrystal extends to 90%.

  19. Synthesis of fullerene-, carbon nanotube-, and graphene-TiO₂ nanocomposite photocatalysts for selective oxidation: a comparative study.

    PubMed

    Yang, Min-Quan; Zhang, Nan; Xu, Yi-Jun

    2013-02-01

    A series of TiO(2)-graphene (GR), -carbon nanotube (CNT), and -fullerene (C(60)) nanocomposite photocatalysts with different weight addition ratios of carbon contents are synthesized via a combination of sol-gel and hydrothermal methods. Their structures and properties are determined by the X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (DRS), transmission electron microscopy (TEM), nitrogen adsorption-desorption, and photoelectrochemical measurements. Photocatalytic selective oxidation of benzyl alcohol to benzaldehyde is employed as a model reaction to evaluate the photocatalytic activity of the TiO(2)-carbon (GR, CNT, and C(60)) nanocomposites under visible light irradiation. The results reveal that incorporating TiO(2) with carbon materials can extend the adsorption edge of all the TiO(2)-carbon nanocomposites to the visible light region. For TiO(2)-GR, TiO(2)-CNT, and TiO(2)-C(60) nanocomposites, the photocatalytic activities of the composites with optimum ratios, TiO(2)-0.1% GR, TiO(2)-0.5% CNT, and TiO(2)-1.0% C(60), are very close to each other along with the irradiation time. Furthermore, the underlying reaction mechanism for the photocatalytic selective oxidation of benzyl alcohol to benzaldehyde over TiO(2)-carbon nanocomposites has been explored using different radical scavenger techniques, suggesting that TiO(2)-carbon photocatalysts follow the analogous oxidation mechanism toward selective oxidation of benzyl alcohol. The addition of different carbon materials has no significant influence on the crystal phase, particle size, and the morphology of TiO(2). Therefore, it can be concluded, at least for nanocomposites of TiO(2)-carbon (GR, CNT, and C(60)) obtained by the present approach, that there is no much difference in essence on affecting the photocatalytic performance of semiconductor TiO(2) among these three different carbon allotropes, GR, CNT, and C(60). Our findings point to the importance of a comparative study of semiconductor

  20. Highly efficient TiO2-based microreactor for photocatalytic applications.

    PubMed

    Krivec, Matic; Žagar, Kristina; Suhadolnik, Luka; Čeh, Miran; Dražić, Goran

    2013-09-25

    A photocatalytic, TiO2-based microreactor is designed and fabricated on a metal-titanium foil. The microchannel is mechanically engraved in the substrate foil, and a double-layered TiO2 anatase film is immobilized on its inner walls with a two-step synthesis, which included anodization and a hydrothermal treatment. X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirm the presence of an approximately 10-μm-thick layer of titania nanotubes and anatase nanoparticles. The SEM and transmission electron microscopy (TEM) of the cross sections show a dense interface between the titanium substrate and the TiO2 nanotubes. An additional layer of TiO2-anatase nanoparticles on the top of the film provides a large, photocatalytic surface area. The metal-titanium substrate with a functionalized serpentine channel is sealed with UV-transparent Plexiglas, and four 0.8-mW UV LEDs combined with a power controller on a small printed-circuit board are fixed over the substrate. The photocatalytic activity and the kinetic properties for the degradation of caffeine are provided, and the longer-term stability of the TiO2 film is evaluated. The results show that after 6 months of use and 3600 working cycles the microreactor still exhibits 60% of its initial efficiency.