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Sample records for incorporating tio2 nanotube

  1. In vitro bioactivity and corrosion resistance of Zr incorporated TiO2 nanotube arrays for orthopaedic applications

    NASA Astrophysics Data System (ADS)

    Indira, K.; KamachiMudali, U.; Rajendran, N.

    2014-10-01

    The present investigation deals with the incorporation of zirconium (Zr) ions onto TiO2 nanotube arrays (TNT) by simple dip coating method for biomedical implants. The electrochemical behaviour of the specimens were studied with potentiodynamic polarization (Tafel plots) and electrochemical impedance spectroscopy (EIS), while surface analysis involved field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), attenuated total reflectance fourier transform infrared (ATR-FTIR) spectroscopy, thin film x-ray diffraction (TF-XRD) and contact angle measurements. The FE-SEM morphology revealed that self-organised TNT was tightly arrayed with an average diameter of 110 ± 4 nm. The wall thickness and length of 15 ± 2 nm and 2.1 ± 0.3 μm respectively were developed by electrochemical anodization of titanium sheet in a mixture of ethylene glycol and NH4F electrolyte. The EDS, ATR-FTIR and TF-XRD studies were revealed the incorporation of Zr onto TNT specimens. Hydroxyapatite (HAp) was grown over Zr ions incorporated TNT (Zr-TNT) via in vitro immersion method. The HAp grown Zr-TNT exhibited higher bioactivity as well as enhanced corrosion resistance when compared to other specimen. Hence, Zr-TNT could be a viable material for the use as orthopaedic implant with good bioactivity and corrosion resistance.

  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. PMID:25792833

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    PubMed Central

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

    2016-01-01

    Titanium dioxide (TiO2) nanotubes are promising for a wide variety of potential applications in energy, biomedical and environmental sectors. However, their low mechanical strength and wide band gap limit their widespread technological use. This article reports our recent efforts to increase the mechanical strength of TiO2 nanotubes with lowered band gap by immobilizing a peptide of D-amino K122-4 (D) onto the nanotubes. Topographies and chemical compositions of the peptide-coated and uncoated TiO2 nanotubular arrays were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy (XPS). Properties of the peptide-coated and uncoated TiO2 nanotubular arrays, including hardness, elastic modulus, electron work function and photocurrent, were evaluated using micromechanical probe, Kelvin Probe and electrochemical system. Effect of the peptide on surface conductivity was also investigated through current mapping and I–V curve analysis with conductive atomic force microscopy. It is demonstrated that the peptide coating simultaneously enhances the mechanical strength, photocatalytic and electrical properties of TiO2 nanotubes. PMID:26915564

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

    PubMed Central

    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 (R2 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. PMID:25792833

  6. Both Enhanced Biocompatibility and Antibacterial Activity in Ag-Decorated TiO2 Nanotubes

    PubMed Central

    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. PMID:24124484

  7. 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.

  8. Electrochemical characterization of TiO2/WOx nanotubes for photocatalytic application

    PubMed Central

    2014-01-01

    TiO2/WOx nanotubes have unique photo-energy retention properties that have gathered scientific interest. Herein, we report the synthesis, morphological characterization, and the electrochemical characterization of TiO2/WOx nanotubes compared with pure TiO2 nanotubes, prepared by anodization technique. Significant structural differences were not observed in TiO2/WOx nanotubes as observed by using scanning electron microscopy and transmission electron microscopy. The charge transfer resistance of TiO2/WOx before and after photo irradiation determined by using electrochemical impedance spectroscopy proves the inherent energy retention property which was not observed in pure TiO2 nanotubes. PMID:25346647

  9. 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.

  10. 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. PMID:27287140

  11. 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.

  12. Preparation and photocatalytic activity of bicrystal phase TiO2 nanotubes containing TiO2-B and anatase

    NASA Astrophysics Data System (ADS)

    Huang, Chuanxi; Zhu, Kerong; Qi, Mengyao; Zhuang, Yonglong; Cheng, Chao

    2012-06-01

    Bicrystal phase TiO2 nanotubes (NTS) containing monoclinic TiO2-B and anatase were prepared by the hydrothermal reaction of anatase nanoparticles with NaOH aqueous solution and a heat treatment. Their structure was characterized by XRD, TEM and Raman spectra. The results showed that the bicrystal phase TiO2 NTS were formed after calcining H2Ti4O9·H2O NTS at 573 K. The bicrystal phase TiO2 NTS exhibit significantly higher photocatalytic activity than the single phase anatase NTS and Dessuga P-25 nanoparticles in the degradation of Methyl Orange aqueous solution under ultraviolet light irradiation, which is attributed to the large surface and interface areas of the bicrystal phase TiO2 NTS.

  13. 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. PMID:24991506

  14. Effect of TiO2 nanotubes arrays on osseointegration of orthodontic miniscrew.

    PubMed

    Jang, Insan; Shim, Seong-Cheol; Choi, Dong-Soon; Cha, Bong-Kuen; Lee, Jae-Kwan; Choe, Byung-Hak; Choi, Won-Youl

    2015-08-01

    To increase the stability of orthodontic miniscrews, TiO2 nanotube arrays were fabricated on the surface of Ti miniscrews and the effect of those arrays on the osseointegration of miniscrews was evaluated. Highly ordered TiO2 nanotube arrays were grown on the surface of orthodontic miniscrews. Ethylene glycol based electrolyte was used in the anodic oxidation process. Two-step anodic oxidation was conducted to obtain clean and open windows in TiO2 nanotube arrays. The diameter and length of the TiO2 nanotube arrays were ~ 70 nm and ~ 5 μm, respectively. The miniscrews with TiO2 nanotube arrays were implanted in the legs of New Zealand white rabbits for 8 weeks. Histological osseointegration was assessed by bone-to-implant contact ratio, and three-dimensional bone volume ratio was measured by micro-computed tomography analysis. The miniscrews with TiO2 nanotube arrays had a greater mean bone-to-implant contact ratio of 52.8 % than the control, 29.3 %. Mean bone volume ratio (BV/TV) was also higher in the miniscrews with TiO2 nanotube arrays, at 81.2 % than those in the control via micro-CT analysis. Our findings support that TiO2 nanotube arrays on the surface of miniscrews enhance osseointegration and improve the stability of the miniscrew.

  15. Effect of TiO2 nanotubes arrays on osseointegration of orthodontic miniscrew.

    PubMed

    Jang, Insan; Shim, Seong-Cheol; Choi, Dong-Soon; Cha, Bong-Kuen; Lee, Jae-Kwan; Choe, Byung-Hak; Choi, Won-Youl

    2015-08-01

    To increase the stability of orthodontic miniscrews, TiO2 nanotube arrays were fabricated on the surface of Ti miniscrews and the effect of those arrays on the osseointegration of miniscrews was evaluated. Highly ordered TiO2 nanotube arrays were grown on the surface of orthodontic miniscrews. Ethylene glycol based electrolyte was used in the anodic oxidation process. Two-step anodic oxidation was conducted to obtain clean and open windows in TiO2 nanotube arrays. The diameter and length of the TiO2 nanotube arrays were ~ 70 nm and ~ 5 μm, respectively. The miniscrews with TiO2 nanotube arrays were implanted in the legs of New Zealand white rabbits for 8 weeks. Histological osseointegration was assessed by bone-to-implant contact ratio, and three-dimensional bone volume ratio was measured by micro-computed tomography analysis. The miniscrews with TiO2 nanotube arrays had a greater mean bone-to-implant contact ratio of 52.8 % than the control, 29.3 %. Mean bone volume ratio (BV/TV) was also higher in the miniscrews with TiO2 nanotube arrays, at 81.2 % than those in the control via micro-CT analysis. Our findings support that TiO2 nanotube arrays on the surface of miniscrews enhance osseointegration and improve the stability of the miniscrew. PMID:26149697

  16. 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.

  17. 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.

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

    PubMed

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

    2012-03-01

    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. PMID:22297577

  19. 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. PMID:27547630

  20. 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

  1. 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.

  2. Enhanced conversion efficiency of dye-sensitized solar cells using a CNT-incorporated TiO2 slurry-based photoanode

    NASA Astrophysics Data System (ADS)

    Cai, Jiaoping; Chen, Zexiang; Li, Jun; Wang, Yan; Xiang, Dong; Zhang, Jijun; Li, Hai

    2015-02-01

    A new titanium dioxide (TiO2) slurry formulation is herein reported for the fabrication of TiO2 photoanode for use in dye-sensitized solar cells (DSSCs). The prepared TiO2 photoanode featured a highly uniform mesoporous structure with well-dispersed TiO2 nanoparticles. The energy conversion efficiency of the resulting TiO2 slurry-based DSSC was ˜63% higher than that achieved by a DSSC prepared using a commercial TiO2 slurry. Subsequently, the incorporation of acid-treated multi-walled carbon nanotubes (CNTs) into the TiO2 slurry was examined. More specifically, the effect of varying the concentration of the CNTs in this slurry on the performance of the resulting DSSCs was studied. The chemical state of the CNTs-incorporated TiO2 photoanode was investigated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. A high energy conversion efficiency of 6.23% was obtained at an optimum CNT concentration of ˜0.06 wt.%. The obtained efficiency corresponds to a 63% enhancement when compared with that obtained from a DSSC based on a commercial TiO2 slurry. The higher efficiency was attributed to the improvement in the collection and transport of excited electrons in the presence of the CNTs.

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

    PubMed

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

    2016-06-29

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

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

    PubMed

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

    2016-06-29

    The chemical inertness of carbon nanotubes (CNT) requires some degree of "defect engineering" for controlled deposition of metal oxides through atomic layer deposition (ALD). The type, quantity, and distribution of such defects rules the deposition rate and defines the growth behavior. In this work, we employed ALD to grow titanium oxide (TiO2) on vertically aligned carbon nanotubes (VACNT). The effects of nitrogen doping and oxygen plasma pretreatment of the CNT on the morphology and total amount of TiO2 were systematically studied using transmission electron microscopy, Raman spectroscopy, and thermogravimetric analysis. The induced chemical changes for each functionalization route were identified by X-ray photoelectron and Raman spectroscopies. The TiO2 mass fraction deposited with the same number of cycles for the pristine CNT, nitrogen-doped CNT, and plasma-treated CNT were 8, 47, and 80%, respectively. We demonstrate that TiO2 nucleation is dependent mainly on surface incorporation of heteroatoms and their distribution rather than structural defects that govern the growth behavior. Therefore, selecting the best way to functionalize CNT will allow us to tailor TiO2 distribution and hence fabricate complex heterostructures. PMID:27269125

  5. Highly flexible coaxial nanohybrids made from porous TiO2 nanotubes.

    PubMed

    Wang, Daoai; Liu, Ying; Wang, Chengwei; Zhou, Feng; Liu, Weimin

    2009-05-26

    Anatase TiO(2), an n-type semiconductor, has gained considerable research interest over several decades due to its photocatalytic activity. Most recently, its properties for photoelectrical conversion in solar cells has been explored. Anodized TiO(2) nanotube (NT) arrays have been developed and possess improved photocatalytic, sensing, photoelectrolystic, and photovoltaic properties. The present work describes using TiO(2) as the building block to form ordered heterojunctions via simple electrodeposition with materials of potential interest, including conducting polymers (polypyrrole, poly(3-hexylthiophene)), inorganic semiconducting materials (CdS), and metals (Ni and Au, etc.). A key finding is that the synthesized TiO(2) NT-nanowires(nanotubes) nanohybrids are highly flexible after being peeled off from mother substrates, which is in contrast to more fragile pure TiO(2) NTs. These highly flexible coaxial nanohybrids are expected to have potent applications.

  6. 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.

  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. PMID:23512241

  8. Room temperature alcohol sensing by oxygen vacancy controlled TiO2 nanotube array

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    Oxygen vacancy (OV) controlled TiO2 nanotubes, having diameters of 50-70 nm and lengths of 200-250 nm, were synthesized by electrochemical anodization in the mixed electrolyte comprising NH4F and ethylene glycol with selective H2O content. The structural evolution of TiO2 nanoforms has been studied by field emission scanning electron microscopy. Variation in the formation of OVs with the variation of the structure of TiO2 nanoforms has been evaluated by photoluminescence and X-ray photoelectron spectroscopy. The sensor characteristics were correlated to the variation of the amount of induced OVs in the nanotubes. The efficient room temperature sensing achieved by the control of OVs of TiO2 nanotube array has paved the way for developing fast responding alcohol sensor with corresponding response magnitude of 60.2%, 45.3%, and 36.5% towards methanol, ethanol, and 2-propanol, respectively.

  9. 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.

  10. 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

  11. Lithium intercalation and diffusion in TiO2 nanotubes: a first-principles investigation.

    PubMed

    Liang, Ke; Chen, Xue; Guo, Zhenyu; Hou, Tingjun; Zhang, Xiaohong; Li, Youyong

    2016-09-21

    Titanium dioxide nanotubes have attracted considerable attention because of their excellent photoelectric and electrochemical performance in lithium-ion batteries (LIBs). Precise intercalation sites and controllable diffusion paths are very important for the structures and transport properties of TiO2 nanotubes. Based on first-principles calculations, herein, we discuss these parameters. The results indicate that TiO2 nanotubes with 2-coordinate oxygen vacancies could effectively improve the immigration ability of Li ions. The effective diffusion barriers (0.53 eV) between the outer and inner surfaces suggest a potential material for application in Li-ion barriers. PMID:27533347

  12. OH radical generation in a photocatalytic reactor using TiO2 nanotube plates.

    PubMed

    Lee, Kangpyung; Ku, Haemin; Pak, Daewon

    2016-04-01

    In order to use TiO2 nanotubes grown on a Ti plate as a photocatalyst, self-organized oxide nanotube layers were grown by anodization in a glycerol based electrolyte. The ultimate conditions for the synthesis of the TiO2 nanotube array on the Ti plate were investigated by comparing the morphology, length, and inner diameter of the nanotubes. They were significantly affected by the applied anodic voltage, anodization time, and composition of the electrolyte such as the water and fluoride ion concentration. The crystallographic structures of TiO2 nanotubes before and after annealing were compared. The photocatalytic reactor used in this study consisted of two parallel and closely spaced TiO2 nanotube plates. The plates were squares while a UV lamp was inserted perpendicularly to them. OH radical generation in the photocatalytic reactor was monitored by using a probe compound, parachlorobenzoate (pCBA). The steady state OH radical concentration was compared depending on the length of nanotubes and crystallographic structure. The longer the nanotubes, the higher the steady state OH radical concentration.

  13. OH radical generation in a photocatalytic reactor using TiO2 nanotube plates.

    PubMed

    Lee, Kangpyung; Ku, Haemin; Pak, Daewon

    2016-04-01

    In order to use TiO2 nanotubes grown on a Ti plate as a photocatalyst, self-organized oxide nanotube layers were grown by anodization in a glycerol based electrolyte. The ultimate conditions for the synthesis of the TiO2 nanotube array on the Ti plate were investigated by comparing the morphology, length, and inner diameter of the nanotubes. They were significantly affected by the applied anodic voltage, anodization time, and composition of the electrolyte such as the water and fluoride ion concentration. The crystallographic structures of TiO2 nanotubes before and after annealing were compared. The photocatalytic reactor used in this study consisted of two parallel and closely spaced TiO2 nanotube plates. The plates were squares while a UV lamp was inserted perpendicularly to them. OH radical generation in the photocatalytic reactor was monitored by using a probe compound, parachlorobenzoate (pCBA). The steady state OH radical concentration was compared depending on the length of nanotubes and crystallographic structure. The longer the nanotubes, the higher the steady state OH radical concentration. PMID:26855214

  14. Formation of anatase TiO2 nanoparticles on carbon nanotubes.

    PubMed

    Lee, Seung-woo; Sigmund, Wolfgang M

    2003-03-21

    Anatase TiO2 nanoparticles with a size range of 2 to 10 nm have been formed on carbon nanotubes by the controlled hydrolysis and condensation of titanium bis-ammonium lactato dihydroxide in water and electrosterically dispersed carbon nanotubes.

  15. 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.

  16. Preparation and characterization of whey protein film incorporated with TiO2 nanoparticles.

    PubMed

    Zhou, J J; Wang, S Y; Gunasekaran, S

    2009-09-01

    Biodegradable titanium dioxide (TiO(2))/whey protein isolate (WPI) blend films were made by casting denatured WPI film solutions incorporated with TiO(2) nanoparticles. X-ray diffraction, UV-vis spectra, and fluorescence spectra of the films showed the successful incorporation of TiO(2) nanoparticles into the WPI matrix and indicated the interactions between TiO(2) and WPI. Mechanical tests revealed the antiplasticizing effect of TiO(2) nanoparticles on the WPI/TiO(2) film. Small amounts (<1 wt%) of added TiO(2) nanoparticles significantly increase the tensile properties of WPI film, but also decrease the moisture barrier properties. The addition of higher amounts (>1 wt%) of TiO(2) improves moisture barrier properties but lowers the tensile properties of the film. Microstructural evaluation confirmed the aggregation and distribution of TiO(2) nanoparticles within the WPI matrix and validated the results of functional properties of the WPI/TiO(2) film.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. TiO2 Nanotube Array Sensor for Detecting the SF6 Decomposition Product SO2

    PubMed Central

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

    2012-01-01

    The detection of partial discharge through analysis of SF6 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 TiO2 nanotube array sensor for detecting the SF6 decomposition product SO2, and the application of the anodic oxidation method for the directional growth of highly ordered TiO2 nanotube arrays. The sensor response of 10–50 ppm SO2 gas is tested, and the sensitive response mechanism is discussed. The test results show that the TiO2 nanotube sensor array has good response to SO2 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. PMID:22737009

  2. Effects of functionalization of TiO2 nanotube array sensors with Pd nanoparticles on their selectivity.

    PubMed

    Park, Sunghoon; Kim, Soohyun; Park, Suyoung; Lee, Wan In; Lee, Chongmu

    2014-08-27

    This study compared the responses of Pd-functionalized and pristine titanate (TiO2) nanotube arrays to ethanol with those to acetone to determine the effects of functionalization of TiO2 nanotubes with Pd nanoparticles on the sensitivity and selectivity. The responses of pristine and Pd-functionalized TiO2 nanotube arrays to ethanol gas at 200 °C were ~2877% and ~21,253%, respectively. On the other hand, the responses of pristine and Pd-functionalized TiO2 nanotube arrays to acetone gas at 250 °C were ~1636% and 8746% respectively. In the case of ethanol sensing, the response and recovery times of Pd-functionalized TiO2 nanotubes (10.2 and 7.1 s) were obviously shorter than those of pristine TiO2 nanotubes (14.3 and 8.8 s), respectively. In contrast, in the case of acetone sensing the response and recovery times of Pd-functionalized TiO2 nanotubes (42.5 and 19.7 s) were almost the same as those of pristine TiO2 nanotubes (47.2 and 17.9 s). TiO2 nanotube arrays showed the strongest response to ethanol and Pd functionalization was the most effective in improving the response of TiO2 nanotubes to ethanol among six different types of gases: ethanol, acetone, CO, H2, NH3 and NO2. The origin of the superior sensing properties of Pd-functionalized TiO2 nanotubes toward ethanol to acetone is also discussed.

  3. Growth and characterization of TiO2 nanotubes from sputtered Ti film on Si substrate

    NASA Astrophysics Data System (ADS)

    Chappanda, Karumbaiah N.; Smith, York R.; Mohanty, Swomitra K.; Rieth, Loren W.; Tathireddy, Prashant; Misra, Mano

    2012-07-01

    In this paper, we present the synthesis of self-organized TiO2 nanotube arrays formed by anodization of thin Ti film deposited on Si wafers by direct current (D.C.) sputtering. Organic electrolyte was used to demonstrate the growth of stable nanotubes at room temperature with voltages varying from 10 to 60 V (D.C.). The tubes were about 1.4 times longer than the thickness of the sputtered Ti film, showing little undesired dissolution of the metal in the electrolyte during anodization. By varying the thickness of the deposited Ti film, the length of the nanotubes could be controlled precisely irrespective of longer anodization time and/or anodization voltage. Scanning electron microscopy, atomic force microscopy, diffuse-reflectance UV-vis spectroscopy, and X-ray diffraction were used to characterize the thin film nanotubes. The tubes exhibited good adhesion to the wafer and did not peel off after annealing in air at 350 °C to form anatase TiO2. With TiO2 nanotubes on planar/stable Si substrates, one can envision their integration with the current micro-fabrication technique large-scale fabrication of TiO2 nanotube-based devices.

  4. 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.

  5. 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. PMID:26249588

  6. 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.

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

    PubMed Central

    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. PMID:25589038

  8. TiO2 nanotube structures for enhanced cell and biological functionality

    NASA Astrophysics Data System (ADS)

    Brammer, Karla S.; Oh, Seunghan; Frandsen, Christine J.; Jin, Sungho

    2010-04-01

    Nanostructures have pronounced effects on biological processes such as growth of cells and their functionality. Advances in biomaterial surface structure and design have resulted in improved tissue engineering. Nanotechnology can be utilized for optimization of titanium implants with a formation of vertically aligned TiO2 nanotube arrays on the implant surface. The anodic oxidation of the titanium implant surface to form a TiO2 nanotube array involves electrochemical processes and self assembly. In this paper, the mechanism of nanotube formation, nanotube bio-characteristics, and their emerging role in soft and hard tissue engineering as well as in regenerative medicine will be reviewed, and the beneficial effects of surface nanotubes on cell adhesion, proliferation, and functionality will be discussed in relation to potential orthopedics applications.

  9. 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.

  10. Facile electrochemical synthesis of antimicrobial TiO2 nanotube arrays

    PubMed Central

    Zhao, Yu; Xing, Qi; Janjanam, Jagadeesh; He, Kun; Long, Fei; Low, Ke-Bin; Tiwari, Ashutosh; Zhao, Feng; Shahbazian-Yassar, Reza; Friedrich, Craig; Shokuhfar, Tolou

    2014-01-01

    Infection-related complications have been a critical issue for the application of titanium orthopedic implants. The use of Ag nanoparticles offers a potential approach to incorporate antimicrobial properties into the titanium implants. In this work, a novel and simple method was developed for synthesis of Ag (II) oxide deposited TiO2 nanotubes (TiNTs) using electrochemical anodization followed by Ag electroplating processes in the same electrolyte. The quantities of AgO nanoparticles deposited in TiNT were controlled by selecting different electroplating times and voltages. It was shown that AgO nanoparticles were crystalline and distributed throughout the length of the nanotubes. Inductively coupled plasma mass spectrometry tests showed that the quantities of released Ag were less than 7 mg/L after 30 days at 37°C. Antimicrobial assay results show that the AgO-deposited TiNTs can effectively kill the Escherichia coli bacteria. Although the AgO-deposited TiNTs showed some cytotoxicity, it should be controllable by optimization of the electroplating parameters and incorporation of cell growth factor. The results of this study indicated that antimicrobial properties could be added to nanotextured medical implants through a simple and cost effective method. PMID:25429214

  11. Amine functionalized TiO2-carbon nanotube composite: synthesis, characterization and application to glucose biosensing

    NASA Astrophysics Data System (ADS)

    Tasviri, Mahboubeh; Rafiee-Pour, Hossain-Ali; Ghourchian, Hedayatollah; Gholami, Mohammad Reza

    2011-12-01

    The synthesis of amine functionalized TiO2-coated multiwalled carbon nanotubes (NH2-TiO2-CNTs) using sol-gel method was investigated. The synthesized nanocomposite was characterized with XRD, FTIR spectroscopy, BET test and SEM imaging. The results demonstrated a unique nanostructure with no destruction of the CNTs' shape. In addition, the presence of amine groups on the composite surface was confirmed by FTIR. This nanocomposite was used for one-step immobilization of glucose oxidase (GOx) to sense glucose. The result of cyclic voltammetry showed a pair of well-defined and quasi-reversible peaks for direct electron transfer of GOx in the absence of glucose. Also, the result of electrochemical impedance spectroscopy indicated that GOx was successfully immobilized on the surface of NH2-TiO2-CNTs. Furthermore, good amperometric response showed that immobilized GOx on the NH2-TiO2-CNTs exhibits exceptional bioelectrocatalytic activity toward glucose oxidation.

  12. 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.

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

    PubMed

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

    2015-08-01

    The significantly enhanced osteoblast adhesion, proliferation and alkaline phosphatase (ALP) activity were observed on TiO2 nanotube surface in recent studies in which the scale of nanotube diameter was restricted under 100 nm. In this paper, a series of highly ordered TiO2 nanotube arrays with larger diameters ranging from 150 nm to 470 nm were fabricated via high voltage anodization. The behaviors of MC3T3-E1 cells in response to the diameter-controlled TiO2 nanotubes were investigated. A contrast between the trend of proliferation and the trend of cell elongation was observed. The highest cell elongation (nearly 10:1) and the lowest cell number were observed on the TiO2 nanotube arrays with 150 nm diameter. While, the lowest cell elongation and highest cell number were achieved on the TiO2 nanotube arrays with 470 nm diameter. Furthermore, the ALP activity peaked on the 150 nm diameter TiO2 nanotube arrays and decreased dramatically with the increase of nanotube diameter. Thus a narrow range of diameter (100-200 nm) that could induce the greatest bone-forming activity is determined. It is expected that more delicate design of orthopedic implant with regional abduction of cell proliferation or bone forming could be achieved by controlling the diameter of TiO2 nanotubes.

  14. Electron field emission from TiO2 nanotube arrays synthesized by hydrothermal reaction

    NASA Astrophysics Data System (ADS)

    Miyauchi, Masahiro; Tokudome, Hiromasa; Toda, Yoshitake; Kamiya, Toshio; Hosono, Hideo

    2006-07-01

    Conductive TiO2 nanotube arrays were grown on metal Ti substrates by hydrothermal reaction and subsequent postannealing in vacuum. The nanotubes were vertically grown and adhered well to the substrates. The crystal structure of the postannealed TiO2 nanotubes was identified to be oxygen-defective anatase. The nanotube arrays exhibited efficient electron field emission even at room temperature with rather low turn-on fields ˜280V per electrode distance of 100μm. The emission current density exceeded 0.15mA /cm2 at an extraction voltage of 800V. The emission current was reproducible and stable in the lower voltage (<800V) region.

  15. 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

    2012-11-01

    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.

  16. 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

  17. 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. PMID:27451743

  18. 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.

  19. Fabrication of anti-aging TiO2 nanotubes on biomedical Ti alloys.

    PubMed

    Hamlekhan, Azhang; Butt, Arman; Patel, Sweetu; Royhman, Dmitry; Takoudis, Christos; Sukotjo, Cortino; Yuan, Judy; Jursich, Gregory; Mathew, Mathew T; Hendrickson, William; Virdi, Amarjit; Shokuhfar, Tolou

    2014-01-01

    The primary objective of this study was to fabricate a TiO2 nanotubular surface, which could maintain hydrophilicity over time (resist aging). In order to achieve non-aging hydrophilic surfaces, anodization and annealing conditions were optimized. This is the first study to show that anodization and annealing condition affect the stability of surface hydrophilicity. Our results indicate that maintenance of hydrophilicity of the obtained TiO2 nanotubes was affected by anodization voltage and annealing temperature. Annealing sharply decreased the water contact angle (WCA) of the as-synthesized TiO2 nanotubular surface, which was correlated to improved hydrophilicity. TiO2 nanotubular surfaces are transformed to hydrophilic surfaces after annealing, regardless of annealing and anodization conditions; however, WCA measurements during aging demonstrate that surface hydrophilicity of non-anodized and 20 V anodized samples decreased after only 11 days of aging, while the 60 V anodized samples maintained their hydrophilicity over the same time period. The nanotubes obtained by 60 V anodization followed by 600 °C annealing maintained their hydrophilicity significantly longer than nanotubes which were obtained by 60 V anodization followed by 300 °C annealing.

  20. Unexpected adsorption of oxygen on TiO2 nanotube arrays: influence of crystal structure.

    PubMed

    Funk, S; Hokkanen, B; Burghaus, U; Ghicov, A; Schmuki, P

    2007-04-01

    We present kinetics data of O2, n/iso-butane, CO2, and CO adsorbed at ultrahigh vacuum conditions on TiO2 nanotube (TiNTs) arrays produced by electrochemical anodization; amorphous and polycrystalline (anatase and mixed anatase/rutile) TiNTs have been studied addressing structure-activity relationships. Oxygen distinctly interacts with the TiNTs, whereas this process is not observed on fully oxidized TiO2 single crystals. Both molecularly and atomically bonded oxygen have been observed. Variations in the binding energies of alkanes were also detected.

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

    DOE PAGESBeta

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

    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.

  2. 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.

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

    PubMed

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

    2014-04-01

    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.

  4. 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.

  5. 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. PMID:27229518

  6. Temperature dependence of Young's modulus of titanium dioxide (TIO2) nanotubes: Molecular mechanics modeling

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    Temperature dependence of the Young's modulus of cylindrical single-wall nanotubes with zigzag and armchair chiralities and consolidated-wall nanotubes has been studied by the molecular mechanics method with the use of the atom-atom potential. The nanotubes have been obtained by rolling up of crystal layers (111) of TiO2 with fluorite structure. Calculations have been performed for isothermal conditions on the basis of calculating the Helmholtz free energy of the system. The dependence of the Helmholtz free energy of nanotubes on the period has been calculated in the quasi-harmonic approximation as a result of calculation of phonon frequencies. It has been shown that the temperature dependence of the stiffness of nanotubes is determined by their chirality, and some nanotubes exibit anomalous behavior of both the Young's modulus and the period of unit cell with variation in temperature.

  7. Optimum Thickness Conditions of TiO2 Nanotubes Layer for Efficient Electrochemical Luminescence Cells Application.

    PubMed

    Choi, Min-Ki; Sung, Youl-Moon; Park, Min-Woo

    2015-02-01

    We report a TiO2 nanotubes (NTs)-based Electrochemical luminescence (ECL) cell. The ECL cell was fabricated using the electrode of TiO2 NTs and Ru(II) complex (Ru(bpy)2+(3)) as a luminescence materials. The fabricated ECL cell is composed of F-doped SnO2 (FTO) glass/Ru(II)/TiO2 NTs/Ti plate. At a bias voltage of 3 V, the measured ECL efficiencies were 0 Im/W for cell without NTs, 0.03 Im/W for NTs-6.5 µm, 0.07 Im/W for NTs-8 µm and 0.1 Im/W for NTs-10 µm, respectively. The use of Ti02 NTs increases ECL intensities by about 2 times compared to the typical ECL cell without the use of TiO2 NTs.

  8. 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. PMID:27157739

  9. 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

  10. 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.

  11. Improved performance of dye-sensitized solar cells using TiO2 nanotubes infiltrated by TiO2 nanoparticles using a dipping-rinsing-hydrolysis process

    NASA Astrophysics Data System (ADS)

    Lin, Lu-Yin; Chen, Chia-Yuan; Yeh, Min-Hsin; Tsai, Keng-Wei; Lee, Chuan-Pei; Vittal, R.; Wu, Chun-Guey; Ho, Kuo-Chuan

    2013-12-01

    An efficient back-illuminated dye-sensitized solar cell (DSSC) is made with a flexible Ti-foil based photoanode composed of a composite TiO2 film with TiO2 nanotubes (TNT) and TiO2 nanoparticles (TNP). The composite TiO2 film is fabricated through a novel dipping-rinsing-hydrolysis (DRH) process by inserting TiO2 into TNT and sintering the product to form TNP inside TNT. By directly placing TiO2 nanoparticles into TNT, the former grow internally from the base of TNT to occupy it completely. This solves previous problems of incomplete filling of TNP into TNT, which used partial penetration of TiCl4 reactant from the top of the TNT. In the present case, the TNP are grown from the base of TNT. A DSSC containing TNT and TNP prepared in this way shows a photoelectric efficiency of 6.45%, which is much higher than that (4.21%) of a DSSC with untreated TNT. The films are characterized by using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The improvement in the photoelectric efficiency is explained by using electrochemical impedance spectroscopy (EIS), incident photon-to-current conversion efficiency (IPCE) analysis, and UV-absorption spectra analysis.

  12. Conical islands of TiO2 nanotube arrays in the photoelectrode of dye-sensitized solar cells.

    PubMed

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

    2015-01-01

    Ti conical island structures were fabricated using photolithography and the reactive ion etching method. The resulting conical island structures were anodized in ethylene glycol solution containing 0.25 wt% NH4F and 2 vol% H2O, and conical islands composed of TiO2 nanotubes were successfully formed on the Ti foils. The conical islands composed of TiO2 nanotubes were employed in photoelectrodes for dye-sensitized solar cells (DSCs). DSC photoelectrodes based on planar Ti structures covered with TiO2 nanotubes were also fabricated as a reference. The short-circuit current (J sc) and efficiency of DSCs based on the conical island structures were higher than those of the reference samples. The efficiency of DSCs based on the conical island structures reached up to 1.866%. From electrochemical impedance spectroscopy and open-circuit voltage (V oc) decay measurements, DSCs based on the conical island structures exhibited a lower charge transfer resistance at the counter cathode and a longer electron lifetime at the interface of the photoelectrode and electrolyte compared to the reference samples. The conical island structure was very effective at improving performances of DSCs based on TiO2 nanotubes. Graphical AbstractConical islands of TiO2 nanotube arrays are fabricated by an anodizing process with Ti protruding dots which have a conical shape. The conical islands are applied for use in DSC photoelectrodes. DSCs based on the conical islands of TiO2 nanotube arrays have the potential to achieve higher efficiency levels compared to DSCs based on normal TiO2 nanotubes and TiO2 nanoparticles because the conical islands of TiO2 nanotube arrays enlarge the surface area for dye adsorption.

  13. 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.

  14. 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.

  15. 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

  16. Enhanced photocatalytic performance of N-nitrosodimethylamine on TiO2 nanotube based on the role of singlet oxygen.

    PubMed

    Guo, Xiaoyan; Li, Qilin; Zhang, Man; Long, Mingce; Kong, Lulu; Zhou, Qixing; Shao, Huaiqi; Hu, Wanli; Wei, Tingting

    2015-02-01

    N-nitrosodimethylamine (NDMA) photocatalytic degradation performance and mechanism were investigated on the TiO2 nanotube prepared from anatase TiO2 nanopowder in terms of the production of reactive oxygen species including hydroxyl radical, singlet oxygen and superoxide radical. Significantly higher NDMA degradation efficiency was obtained on anatase TiO2 nanotube rather than anatase TiO2 nanopowder. The tubular morphology may be responsible for almost 100% NDMA removal on TiO2 nanotube, presumably due to its confinement effect leading to NDMA molecules within the nanotube being attacked by reactive oxygen species such as hydroxyl radical and singlet oxygen, and initiating reaction inside the nanotube. In particular, the ability of the nanotubular structure of TiO2 nanotube to promote a singlet oxygen oxidation pathway contributes much to the enhanced NDMA degradation efficiency and favors the formation of dimethylamine and NO3(-). Such function originating from nanotube morphology could bring new insights for the photocatalytic degradation of organic pollutants.

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

    PubMed

    Yeniyol, Sinem; He, Zhiming; Yüksel, Behiye; Boylan, Robert Joseph; Urgen, Mustafa; Ozdemir, 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Manipulation of TiO2 Nanotubes in a Transparent Dielectrophoretic Device.

    PubMed

    Seon, Ji-Yun; Yoon, Young Joon; Kim, Chang-Yeoul; Kim, Hyo Tae

    2016-02-01

    A DEP device with a transparent oxide thin film electrode was fabricated by a photolithography process and sputtering deposition with indium tin oxide (ITO). In order to form a fine ITO electrode pattern, we manipulated the negative slope using a photoresist by controlling the intensity of the ultra-violet radiation and the exposure time. In this study, the motions of a 1 microm polystyrene sphere and TiO2 nanotube were observed as a function of the applied voltage and the frequency. The findings confirm that TiO2 nanotubes can be manipulated by a p-DEP force and that they can be effectively aligned under conditions of 10 V(p-p) at 750 Hz. PMID:27433654

  4. Photoelectrochemical characterization of hydrogenated TiO2 nanotubes as photoanodes for sensing applications.

    PubMed

    Li, Sheng; Qiu, Jingxia; Ling, Min; Peng, Feng; Wood, Barry; Zhang, Shanqing

    2013-11-13

    In this work, hydrogenated TiO2 nanotubes (H-TNTs) electrodes were successfully fabricated via the anodization of a titanium sheet followed by a hydrogenation process. Oxygen vacancies were induced in the crystalline structure of TiO2 nanotubes (TNTs) as shallow donors that enhance the electronic conductivity of the TNTs. This improvement in the electronic conductivity and photoelectrocatalytic (PEC) performance was confirmed and evaluated by a photoelectrochemical characterization. Most importantly, the H-TNTs electrode was able to degrade potassium hydrogen phthalate (strong adsorbent) and glucose (weak adsorbent) indiscriminately. The corresponding photocurrents at the H-TNTs were 2-fold greater than that of the TNTs samples for the same concentrations of the organic compounds. This suggests that the H-TNTs electrode can be a promising sensor for the PEC determination of individual organic compounds or as an aggregative parameter of organic compounds (e.g., chemical oxygen demand). PMID:24083843

  5. 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. PMID:27070991

  6. 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.

  7. 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. PMID:24922363

  8. Contact potential barriers and characterization of Ag-doped composite TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Li, Jingling; Chen, Wenzhe; Yu, Hualiang; Wu, Bo; Huang, Wenbo; Wang, Mingxiu; Huang, Shizhen; Lin, Wei; Zhang, Likun; Li, Shiping

    2014-04-01

    Ag-doping TiO2 composite nanotubes (Ag-TNTs) were synthesized by alkaline fusion followed by hydrothermal treatment. The microstructure and morphology of the materials were characterized by XRD, TEM, XPS, SPS (surface photovoltage spectroscopy), FISPS (electric field-induced surface photovoltage spectroscopy) and Raman spectroscopy. First-principles calculations based on density-functional theory (DFT) showed the formation of several impurity levels near the top of the valence band in the band gap (Eg) of rutile TiO2 due to Ag doping. A "double junction" is proposed, involving a Schottky junction and p-n junction (denoted as "Ag-p-n junction") occurring between the Ag particles and the nanotube surface, as well as forming inside TiO2 nanotubes, respectively. The strongly built-in electric field of the junctions promotes the separation of photo-holes and photoelectrons, enhancing the photocatalytic efficiency. XRD results indicated that the composite Ag-TNTs exist as a mixture of anatase and rutile phases. XPS results showed that Ti4+ is the primary state of Ti. Raman spectral analysis of Ag-TNTs revealed the presence of a new peak at 271 cm-1. The red-shift of the absorption light wavelength of Ag-TNTs was 0.16 eV (20 nm) due to a considerable narrowing of Eg by the existing impurity levels.

  9. Photoelectrochemical oxidation of ibuprofen via Cu2O-doped TiO2 nanotube arrays.

    PubMed

    Sun, Qiannan; Peng, Yen-Ping; Chen, Hanlin; Chang, Ken-Lin; Qiu, Yang-Neng; Lai, Shiau-Wu

    2016-12-01

    A p-n junction based Cu2O-doped TiO2 nanotube arrays (Cu2O-TNAs) were synthesized and used as a working anode in a photoelectrochemical (PEC) system. The results revealed that the Cu2O-TNAs were dominated by the anatase phase and responded significantly to visible light. XPS analyses indicated that with an amount of 24.79% Cu doping into the structure, the band gap of Cu2O-TNAs was greatly reduced. SEM images revealed that the supported TiO2 nanotubes had diameters of approximately 80nm and lengths of about 2.63μm. Upon doping with Cu2O, the TiO2 nanotubes maintained their structural integrity, exhibiting no significant morphological change, favoring PEC applications. Under illumination, the photocurrent from Cu2O/TNAs was 2.4 times larger than that from TNAs, implying that doping with Cu2O significantly improved electron mobility by reducing the rate of recombination of electron-hole pairs. The EIS and Bode plot revealed that the estimated electron lifetimes, τel, of TNAs and Cu2O/TNAs were 6.91 and 26.26ms, respectively. The efficiencies of degradation of Ibuprofen by photoelectrochemical, photocatalytic (PC), electrochemical (EC) and photolytic (P) methods were measured. PMID:27021261

  10. 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

  11. 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.

  12. The Synthesis and Photocatalytic Properties of TiO2 Nanotube Array by Starch-Modified Anodic Oxidation.

    PubMed

    Zhang, Fengjun; Liu, Zijian; Lu, Wei; Lyu, Cong; Lyu, Chuan; Wang, Xiansheng

    2015-11-01

    In this study, the characterization and photocatalytic activity of TiO2 nanotube arrays prepared by anodization process with starch addition were investigated in detail. The results suggested that the optimum mass fraction of starch added in anodization process was 0.1%, with which TiO2 nanotube arrays owning good tubular structure were synthesized. The tube length and average inner diameter of nanotubes were approximately 4 μm and 30 nm, respectively. Through the characterization of TiO2 nanotube arrays by energy dispersive spectrometer, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier Transform Infrared (FTIR) spectroscopy, it was found that the as-prepared nanotubes possessed well uniformed and higher photodegradation responsive than the pure TiO2 . Moreover, it was expected that the as-prepared nanotubes exhibited good photocatalytic activity for the degradation of RhB under UV-light irradiation, which could be ascribed to their good morphology, enhanced UV-light absorption property and electron transmission ability during the photocatalytic reaction. In addition, the nanotubes were not significantly regenerated during the cycling runs experiment. Overall, this study could provide a principle method to synthesize TiO2 nanotube arrays with enhanced photocatalytic activity by anodization process with starch addition for environmental purification.

  13. 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

  14. 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

  15. In situ synthesis of TiO2(B) nanotube/nanoparticle composite anode materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Liu, Xiang; Sun, Qian; Ng, Alan M. C.; Djurišić, Aleksandra B.; Xie, Maohai; Liao, Changzhong; Shih, Kaimin; Vranješ, Mila; Nedeljković, Jovan M.; Deng, Zhaofeng

    2015-10-01

    Titania nanotubes were prepared by a simple hydrothermal route. Their electrochemical performance has been examined in detail and compared to TiO2(B) nanoparticles, TiO2 anatase and P25 titania nanoparticles. The cycling and rate performance of TiO2 nanotubes is superior to both types of nanoparticles, and it can be further improved by an in situ titanium precursor treatment, which results in the formation of TiO2 nanoparticles on/between the nanotubes. The obtained specific capacity after 200 cycles at 0.2 A g-1 charge/discharge rate remained above 130 mAh g-1. The enhanced lithium storage properties of these samples can be attributed to their unique morphology and crystal structure.

  16. In situ synthesis of TiO2(B) nanotube/nanoparticle composite anode materials for lithium ion batteries.

    PubMed

    Liu, Xiang; Sun, Qian; Ng, Alan M C; Djurišić, Aleksandra B; Xie, Maohai; Liao, Changzhong; Shih, Kaimin; Vranješ, Mila; Nedeljković, Jovan M; Deng, Zhaofeng

    2015-10-23

    Titania nanotubes were prepared by a simple hydrothermal route. Their electrochemical performance has been examined in detail and compared to TiO2(B) nanoparticles, TiO2 anatase and P25 titania nanoparticles. The cycling and rate performance of TiO2 nanotubes is superior to both types of nanoparticles, and it can be further improved by an in situ titanium precursor treatment, which results in the formation of TiO2 nanoparticles on/between the nanotubes. The obtained specific capacity after 200 cycles at 0.2 A g(-1) charge/discharge rate remained above 130 mAh g(-1). The enhanced lithium storage properties of these samples can be attributed to their unique morphology and crystal structure.

  17. Hybrid bulk heterojunction solar cells from a blend of poly(3-hexylthiophene) and TiO 2 nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Z. J.; Qu, S. C.; Zeng, X. B.; Liu, J. P.; Zhang, C. S.; Tan, F. R.; Jin, L.; Wang, Z. G.

    2008-12-01

    Hybrid bulk heterojunction solar cells based on blend of poly(3-hexylthiophene) (P3HT) and TiO 2 nanotubes or dye(N719) modified TiO 2 nanotubes were processed from solution and characterized to research the nature of organic/inorganic hybrid materials. Compared with the pristine polymer P3HT and TiO 2 nanoparticles/P3HT solar cells, the TiO 2 nanotubes/P3HT hybrid solar cells show obvious performance improvement, due to the formation of the bulk heterojunction and charge transport improvement. A further improvement in the device performance can be achieved by modifying TiO 2 nanotube surface with a standard dye N719 which can play a role in the improvement of both the light absorption and charge dissociation. Compared with the non-modified TiO 2 nanotubes solar cells, the modified ones have better power conversion efficiency under 100 mW/cm 2 illumination with 500 W Xenon lamp.

  18. Synthesis and photocatalytic property of N-doped TiO 2 nanorods and nanotubes with high nitrogen content

    NASA Astrophysics Data System (ADS)

    He, Z.; He, H. Y.

    2011-11-01

    Nano N-doped TiO2 nanotubes were fabricated by hydrothermally treating N-doped TiO2 nanorods in a 8 M NaOH solution at 110 °C for 20 h. The N-doped TiO2 nanorods were synthesized by a solvothermal process with precursor solution containing titanium sulfate, urea, and dichloroethane. The N-doped TiO2 nanorods and nanotubes were characterized with X-ray diffraction, transmission electron microscopy, and UV-vis spectrophotometry. The nitrogen contents of the N-doped TiO2 nanorods and nanotubes were reached to high values of 36.9 at.% and 25.7 at.%, respectively. The nitrogen doping narrowed the band gap of the N-doped TiO2 nanorods and nanotubes and introduced indirect band gap to the powders, which respectively extended the absorption edge to visible light and infrared region. The nanotubes showed larger specific surface area and greater degradation efficiency to methyl orange than the nanorods.

  19. High quantum yield graphene quantum dots decorated TiO2 nanotubes for enhancing photocatalytic activity

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    Graphene quantum dots (GQDs) with high quantum yield (about 23.6% at an excitation wavelength of 320 nm) and GQDs/TiO2 nanotubes (GQDs/TiO2 NTs) composites were achieved by a simple hydrothermal method at low temperature. Photoluminescence characterization showed that the GQDs exhibited the down-conversion PL features at excitation from 300 to 420 nm and up-conversion photoluminescence in the range of 600-800 nm. The photocatalytic activity of prepared GQDs/TiO2 NTs composites on the degradation of methyl orange (MO) was significantly enhanced compared with that of pure TiO2 nanotubes (TiO2 NTs). For the composites coupling with 1.5%, 2.5% and 3.5% GQDs, the degradation of MO after 20 min irradiation under UV-vis light irradiation (λ = 380-780 nm) were 80.52%, 94.64% and 51.91%, respectively, which are much higher than that of pure TiO2 NTs (35.41%). It was inferred from the results of characterization that the improved photocatalytic activity of the GQDs/TiO2 NTs composites was attributed to the synergetic effect of up-conversion properties of the GQDs, enhanced visible light absorption and efficient separation of photogenerated electron-holes of the GQDs/TiO2 composite.

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

    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.

  1. 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.

  2. 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.

  3. 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. PMID:26197106

  4. 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.

  5. Highly efficient solar cells using TiO(2) nanotube arrays sensitized with a donor-antenna dye.

    PubMed

    Shankar, Karthik; Bandara, Jayasundera; Paulose, Maggie; Wietasch, Helga; Varghese, Oomman K; Mor, Gopal K; LaTempa, Thomas J; Thelakkat, Mukundan; Grimes, Craig A

    2008-06-01

    Donor antenna dyes provide an exciting route to improving the efficiency of dye sensitized solar cells owing to their high molar extinction coefficients and the effective spatial separation of charges in the charge-separated state, which decelerates the recombination of photogenerated charges. Vertically oriented TiO(2) nanotube arrays provide an optimal material architecture for photoelectrochemical devices because of their large internal surface area, lower recombination losses, and vectorial charge transport along the nanotube axis. In this study, the results obtained by sensitizing TiO(2) nanotube arrays with the donor antenna dye Ru-TPA-NCS are presented. Solar cells fabricated using an antenna dye-sensitized array of 14.4 microm long TiO(2) nanotubes on Ti foil subjected to AM 1.5 one sun illumination in the backside geometry exhibited an overall conversion efficiency of 6.1%. An efficiency of 4.1% was obtained in the frontside illumination geometry using a 1 microm long array of transparent TiO(2) nanotubes subjected to a TiCl(4) treatment and then sensitized with the Ru-TPA-NCS dye. Open circuit voltage decay measurements give insight into the recombination behavior in antenna-dye sensitized nanotube photoelectrodes, demonstrating outstanding properties likely due to a reduction in the influence of the surface traps and reduced electron transfer from TiO(2) to ions in solution.

  6. Nanoscale TiO2 nanotubes govern the biological behavior of human glioma and osteosarcoma cells.

    PubMed

    Tian, Ang; Qin, Xiaofei; Wu, Anhua; Zhang, Hangzhou; Xu, Quan; Xing, Deguang; Yang, He; Qiu, Bo; Xue, Xiangxin; Zhang, Dongyong; Dong, Chenbo

    2015-01-01

    Cells respond to their surroundings through an interactive adhesion process that has direct effects on cell proliferation and migration. This research was designed to investigate the effects of TiO2 nanotubes with different topographies and structures on the biological behavior of cultured cells. The results demonstrated that the nanotube diameter, rather than the crystalline structure of the coatings, was a major factor for the biological behavior of the cultured cells. The optimal diameter of the nanotubes was 20 nm for cell adhesion, migration, and proliferation in both glioma and osteosarcoma cells. The expression levels of vitronectin and phosphor-focal adhesion kinase were affected by the nanotube diameter; therefore, it is proposed that the responses of vitronectin and phosphor-focal adhesion kinase to the nanotube could modulate cell fate. In addition, the geometry and size of the nanotube coating could regulate the degree of expression of acetylated α-tubulin, thus indirectly modulating cell migration behavior. Moreover, the expression levels of apoptosis-associated proteins were influenced by the topography. In conclusion, a nanotube diameter of 20 nm was the critical threshold that upregulated the expression level of Bcl-2 and obviously decreased the expression levels of Bax and caspase-3. This information will be useful for future biomedical and clinical applications.

  7. 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.

  8. Nanoscale TiO2 nanotubes govern the biological behavior of human glioma and osteosarcoma cells

    PubMed Central

    Tian, Ang; Qin, Xiaofei; Wu, Anhua; Zhang, Hangzhou; Xu, Quan; Xing, Deguang; Yang, He; Qiu, Bo; Xue, Xiangxin; Zhang, Dongyong; Dong, Chenbo

    2015-01-01

    Cells respond to their surroundings through an interactive adhesion process that has direct effects on cell proliferation and migration. This research was designed to investigate the effects of TiO2 nanotubes with different topographies and structures on the biological behavior of cultured cells. The results demonstrated that the nanotube diameter, rather than the crystalline structure of the coatings, was a major factor for the biological behavior of the cultured cells. The optimal diameter of the nanotubes was 20 nm for cell adhesion, migration, and proliferation in both glioma and osteosarcoma cells. The expression levels of vitronectin and phosphor-focal adhesion kinase were affected by the nanotube diameter; therefore, it is proposed that the responses of vitronectin and phosphor-focal adhesion kinase to the nanotube could modulate cell fate. In addition, the geometry and size of the nanotube coating could regulate the degree of expression of acetylated α-tubulin, thus indirectly modulating cell migration behavior. Moreover, the expression levels of apoptosis-associated proteins were influenced by the topography. In conclusion, a nanotube diameter of 20 nm was the critical threshold that upregulated the expression level of Bcl-2 and obviously decreased the expression levels of Bax and caspase-3. This information will be useful for future biomedical and clinical applications. PMID:25848261

  9. 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.

  10. Single-Walled TiO2 Nanotubes: Enhanced Carrier-Transport Properties by TiCl4 Treatment.

    PubMed

    Hwang, Imgon; So, Seulgi; Mokhtar, Mohamed; Alshehri, Abdelmohsen; Al-Thabaiti, Shaeel A; Mazare, Anca; Schmuki, Patrik

    2015-06-15

    In the present work we report significant enhancement of the photoelectrochemical properties of self- organized TiO2 nanotubes by a combined "de-coring" of classic nanotubes followed by an appropiate TiCl4 treatment. We show that, except for the expected particle decoration, a key effect of the TiCl4 treatment is that the electron transport characteristics in TiO2 nanotubes can be drastically improved, for example, we observe an enhancement of up to 70 % in electron-transport times. PMID:25962935

  11. Modification of physicochemical and thermal properties of starch films by incorporation of TiO2 nanoparticles.

    PubMed

    Oleyaei, Seyed Amir; Zahedi, Younes; Ghanbarzadeh, Babak; Moayedi, Ali Akbar

    2016-08-01

    In this research, potato starch and TiO2 nanoparticles (0.5, 1 and 2wt%) films were developed. Influences of different concentrations of TiO2 on the functional properties of nanocomposite films (water-related properties, mechanical characteristics, and UV transmittance) were investigated. XRD, FTIR, and DSC analyses were used to characterize the morphology and thermal properties of the films. The results revealed that TiO2 nanoparticles dramatically decreased the values of water-related properties (water vapor permeability: 11-34%; water solubility: 1.88-9.26%; moisture uptake: 2.15-11.18%). Incorporation of TiO2 led to a slight increment of contact angle and tensile strength, and a decrease in elongation at break of the films. TiO2 successfully blocked more than 90% of UV light, while opacity and white index of the films were enhanced. Glass transition temperature and melting point of the films were positively affected by the addition of TiO2 nanoparticles. The result of XRD study exhibited that due to a limited agglomeration of TiO2 nanoparticles, the mean crystal size of TiO2 increased. Formation of new hydrogen bonds between the hydroxyl groups of starch and nanoparticles was confirmed by FTIR spectroscopy. In conclusion, TiO2 nanoparticles improved the functional properties of potato starch film and extended the potential for food packaging applications. PMID:27132884

  12. 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.

  13. Development of Amperometric Glucose Biosensor Based on Prussian Blue Functionlized TiO2 Nanotube Arrays

    NASA Astrophysics Data System (ADS)

    Gao, Zhi-Da; Qu, Yongfang; Li, Tongtong; Shrestha, Nabeen K.; Song, Yan-Yan

    2014-11-01

    Amperometric biosensors consisting of oxidase and peroxidase have attracted great attention because of their wide application. The current work demonstrates a novel approach to construct an enzymatic biosensor based on TiO2 nanotube arrays (TiNTs) as a supporting electrode on which Prussian Blue (PB)-an ``artificial enzyme peroxidase'' and enzyme glucose oxidase (GOx) have been immobilized. For this, PB nanocrystals are deposited onto the nanotube wall photocatalytically using the intrinsic photocatalytical property of TiO2, and the GOx/AuNPs nanobiocomposites are subsequently immobilized into the nanotubes via the electrodeposition of polymer. The resulting electrode exhibits a fast response, wide linear range, and good stability for glucose sensing. The sensitivity of the sensor is as high as 248 mA M-1 cm-2, and the detection limit is about 3.2 μM. These findings demonstrate a promising strategy to integrate enzymes and TiNTs, which could provide an analytical access to a large group of enzymes for bioelectrochemical applications including biosensors and biofuel cells.

  14. Development of amperometric glucose biosensor based on Prussian Blue functionlized TiO2 nanotube arrays.

    PubMed

    Gao, Zhi-Da; Qu, Yongfang; Li, Tongtong; Shrestha, Nabeen K; Song, Yan-Yan

    2014-01-01

    Amperometric biosensors consisting of oxidase and peroxidase have attracted great attention because of their wide application. The current work demonstrates a novel approach to construct an enzymatic biosensor based on TiO2 nanotube arrays (TiNTs) as a supporting electrode on which Prussian Blue (PB)-an "artificial enzyme peroxidase" and enzyme glucose oxidase (GOx) have been immobilized. For this, PB nanocrystals are deposited onto the nanotube wall photocatalytically using the intrinsic photocatalytical property of TiO2, and the GOx/AuNPs nanobiocomposites are subsequently immobilized into the nanotubes via the electrodeposition of polymer. The resulting electrode exhibits a fast response, wide linear range, and good stability for glucose sensing. The sensitivity of the sensor is as high as 248 mA M(-1) cm(-2), and the detection limit is about 3.2 μM. These findings demonstrate a promising strategy to integrate enzymes and TiNTs, which could provide an analytical access to a large group of enzymes for bioelectrochemical applications including biosensors and biofuel cells. PMID:25367086

  15. 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

  16. Development of Amperometric Glucose Biosensor Based on Prussian Blue Functionlized TiO2 Nanotube Arrays

    PubMed Central

    Gao, Zhi-Da; Qu, Yongfang; Li, Tongtong; Shrestha, Nabeen K.; Song, Yan-Yan

    2014-01-01

    Amperometric biosensors consisting of oxidase and peroxidase have attracted great attention because of their wide application. The current work demonstrates a novel approach to construct an enzymatic biosensor based on TiO2 nanotube arrays (TiNTs) as a supporting electrode on which Prussian Blue (PB)-an “artificial enzyme peroxidase” and enzyme glucose oxidase (GOx) have been immobilized. For this, PB nanocrystals are deposited onto the nanotube wall photocatalytically using the intrinsic photocatalytical property of TiO2, and the GOx/AuNPs nanobiocomposites are subsequently immobilized into the nanotubes via the electrodeposition of polymer. The resulting electrode exhibits a fast response, wide linear range, and good stability for glucose sensing. The sensitivity of the sensor is as high as 248 mA M−1 cm−2, and the detection limit is about 3.2 μM. These findings demonstrate a promising strategy to integrate enzymes and TiNTs, which could provide an analytical access to a large group of enzymes for bioelectrochemical applications including biosensors and biofuel cells. PMID:25367086

  17. Synthesis and enhanced photoelectrocatalytic activity of p-n junction Co3O4/TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Dai, Gaopeng; Liu, Suqin; Liang, Ying; Luo, Tianxiong

    2013-01-01

    Co3O4/TiO2 nanotube arrays (NTs) were prepared by depositing Co3O4 nanoparticles (NPs) on the tube wall of the self-organized TiO2 NTs using an impregnating-deposition-decompostion method. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-vis absorption spectroscopy. The photoelectrocatalytic (PEC) activity is evaluated by degradation of methyl orange (MO) aqueous solution. The prepared Co3O4/TiO2 NTs exhibit much higher PEC activity than TiO2 NTs due to the p-n junction formed between Co3O4 and TiO2.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. Carbon nanotube TiO2 hybrid films for detecting traces of O2

    NASA Astrophysics Data System (ADS)

    Llobet, E.; Espinosa, E. H.; Sotter, E.; Ionescu, R.; Vilanova, X.; Torres, J.; Felten, A.; Pireaux, J. J.; Ke, X.; Van Tendeloo, G.; Renaux, F.; Paint, Y.; Hecq, M.; Bittencourt, C.

    2008-09-01

    Hybrid titania films have been prepared using an adapted sol-gel method for obtaining well-dispersed hydrogen plasma-treated multiwall carbon nanotubes in either pure titania or Nb-doped titania. The drop-coating method has been used to fabricate resistive oxygen sensors based on titania or on titania and carbon nanotube hybrids. Morphology and composition studies have revealed that the dispersion of low amounts of carbon nanotubes within the titania matrix does not significantly alter its crystallization behaviour. The gas sensitivity studies performed on the different samples have shown that the hybrid layers based on titania and carbon nanotubes possess an unprecedented responsiveness towards oxygen (i.e. more than four times higher than that shown by optimized Nb-doped TiO2 films). Furthermore, hybrid sensors containing carbon nanotubes respond at significantly lower operating temperatures than their non-hybrid counterparts. These new hybrid sensors show a strong potential for monitoring traces of oxygen (i.e. <=10 ppm) in a flow of CO2, which is of interest for the beverage industry.

  3. 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.

  4. Carbon cladded TiO2 nanotubes: fabrication and use in 3D-RuO2 based supercapacitors.

    PubMed

    Gao, Zhi-Da; Zhu, Xu; Li, Ya-Hang; Zhou, Xuemei; Song, Yan-Yan; Schmuki, Patrik

    2015-05-01

    In this work we introduce a facile procedure that allows a highly conformal coating of self-organized TiO2 nanotubes (NTs) with a graphite-like thin carbon layer. This provides a platform to enhance the functionality of TiO2 nanotubes for a wide range of applications. Here we show that such modified nanotubes can serve as a 3D scaffold for an ideal decoration with RuO2 nanoparticles. Used as 3D pseudocapacitor electrode, capacitance values of up to 80 times higher than plain TiO2 NTs, and a very high yield of utilization of RuO2 (872 F g(-1)) and excellent long-term cycling stability can be reached. PMID:25848658

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

    DOE PAGESBeta

    Ren, Kai; Gan, Yong X.; Nikolaidis, Efstratios; Sofyani, Sharaf Al; Zhang, Lihua

    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

  6. Mesoporous nanotube aggregates obtained from hydrothermally treating TiO 2 with NaOH

    NASA Astrophysics Data System (ADS)

    Tsai, Chien-Cheng; Nian, Jun-Nan; Teng, Hsisheng

    2006-12-01

    Nanotube aggregates with high porosity were prepared from hydrothermal treatment of TiO 2 particles in NaOH at 130 °C, followed by HCl rinsing to different pH values. Pore structure of the aggregates, which were mainly mesoporous, was characterized by analyzing the N 2 sorption isotherm with different methods including the t-plot and density function theory. The surface area, pore volume and mean pore size of the aggregates increased with the rinsing acidity to reach a maximum (e.g. 400 m 2/g in surface area) at pH 1.6 and then decreased with further increase of the acidity. The crystalline phase and composition of the aggregates were, as well, significantly affected by the acidity of the post-treatment rinsing. Large-surface area aggregates were of loosely-attached nanotubes, composed of both anatase TiO 2 and H 2Ti 2O 5·H 2O, obtained under a mildly acidic rinsing condition, while basic or highly acidic conditions resulted in the formation of closely coagulated dense structures consisting of different crystalline phases.

  7. 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.

  8. Fabrication of highly ordered TiO2 nanotube arrays via anodization of Ti-6Al-4V alloy sheet.

    PubMed

    Wang, Lei; Zhao, Ting-ting; Zhang, Zhao; Li, Gang

    2010-12-01

    Uniform and highly ordered TiO2 nanotube arrays were fabricated by the electrochemical anodic oxidation on Ti-6Al-4V surface, using graphite plate as cathode and ethylene glycol (EG) with addition of a certain amount of H2O and NH4F as electrolyte, and the anodization voltage went up to a presetting voltage by stepwise increment. The morphology, structure and composition of TiO2 nanotube arrays were characterized by SEM, EDS, XRD and XPS. The formation process of TiO2 nanotubes was introduced in brief. The experiments were arranged by an orthogonal experiment method and the experimental results showed that the formation of TiO2 nanotube arrays was influenced by not only each factor (F- content, H2O content, external voltage and duration), but also cross correlation among the four factors. The optimal condition was F- content 0.2 wt%, H2O content 4 vol%, external voltage 40 V and duration 1 h in the studied electrochemical system, and the length of obtained nanotubes was 1.5 microm, the outer diameter was approximately 100 nm and the aspect ratio was 15. As-formed nanotube arrays were amorphous and changed to anatase TiO2 after annealed at 500 degrees C for 2 h in air ambience. XPS survey spectra revealed the surface of as-formed nanotube arrays containing Ti, O, C, F and N. The nanotube arrays on Ti-6Al-4V surface with better thermo-stability and crystallinity would have great potential in biomaterials. PMID:21121333

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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. PMID:25811301

  14. 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.

  15. 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.

  16. Electrodeposition of hydroxyapatite nanoparticles onto ultra-fine TiO2 nanotube layer by electrochemical reaction in mixed electrolyte.

    PubMed

    Park, Su-Jung; Jang, Jae-Myung

    2011-08-01

    Electrochemical depositions of HAp nanoparticles onto Ultra-fine TiO2 nanotube layer were carried out by the electrochemical reaction in mixed electrolyte of 1.6 M (NH4)H2PO4 + 0.8 M NH4F containing 0.15 and 0.25 wt% HAp. The Ca/P ratios of the HAp nanoparticles were evaluated by EDS analysis and their values were 1.53 and 1.66 respectively. The distribution quantity of Ca and P were remained at the middle region of TiO2 nanotube, but the Ti element was mainly stayed at the bottom of barrier layer from the result of line scanning diagram. Especially, adsorbed phosphate ions facilitated nucleation of nanophase calcium phosphate material inside the TiO2 nanotubu layer that resulted in vertical growth of HAp nanoparticles. These surfaces and structures were all effective for biocompatibility from the SBF tests.

  17. Electrochemical growth behavior, surface properties, and enhanced in vivo bone response of TiO2 nanotubes on microstructured surfaces of blasted, screw-shaped titanium implants

    PubMed Central

    Sul, Young-Taeg

    2010-01-01

    TiO2 nanotubes are fabricated on TiO2 grit-blasted, screw-shaped rough titanium (ASTM grade 4) implants (3.75 × 7 mm) using potentiostatic anodization at 20 V in 1 M H3PO4 + 0.4 wt.% HF. The growth behavior and surface properties of the nanotubes are investigated as a function of the reaction time. The results show that vertically aligned nanotubes of ≈700 nm in length, with highly ordered structures of ≈40 nm spacing and ≈15 nm wall thickness may be grown independent of reaction time. The geometrical properties of nanotubes increase with reaction time (mean pore size, pore size distribution [PSD], and porosity ≈90 nm, ≈40–127 nm and 45%, respectively for 30 minutes; ≈107 nm, ≈63–140 nm and 56% for one hour; ≈108 nm, ≈58–150 nm and 60% for three hours). It is found that the fluorinated chemistry of the nanotubes of F-TiO2, TiOF2, and F-Ti-O with F ion incorporation of ≈5 at.%, and their amorphous structure is the same regardless of the reaction time, while the average roughness (Sa) gradually decreases and the developed surface area (Sdr) slightly increases with reaction time. The results of studies on animals show that, despite their low roughness values, after six weeks the fluorinated TiO2 nanotube implants in rabbit femurs demonstrate significantly increased osseointegration strengths (41 vs 29 Ncm; P = 0.008) and new bone formation (57.5% vs 65.5%; P = 0.008) (n = 8), and reveal more frequently direct bone/cell contact at the bone–implant interface by high-resolution scanning electron microscope observations as compared with the blasted, moderately rough implants that have hitherto been widely used for clinically favorable performance. The results of the animal studies constitute significant evidence that the presence of the nanotubes and the resulting fluorinated surface chemistry determine the nature of the bone responses to the implants. The present in vivo results point to potential applications of the TiO2 nanotubes in the

  18. Improved osseointegration of dental titanium implants by TiO2 nanotube arrays with recombinant human bone morphogenetic protein-2: a pilot in vivo study.

    PubMed

    Lee, Jae-Kwan; Choi, Dong-Soon; Jang, Insan; Choi, Won-Youl

    2015-01-01

    TiO2 nanotube arrays on the surface of dental implants were fabricated by two-step anodic oxidation. Their effects on bone-implant contact were researched by a pilot in vivo study. The implants were classified into four groups. An implant group with TiO2 nanotube arrays and recombinant human bone morphogenetic protein-2 (rhBMP-2) was compared with various surface implants, including machined surface, sandblasted large-grit and acid-etched surface, and TiO2 nanotube array surface groups. The diameter of the TiO2 nanotube window and TiO2 nanotube were ~70 nm and ~110 nm, respectively. The rhBMP-2 was loaded into TiO2 nanotube arrays and elution was detected by an interferometric biosensing method. A change in optical thickness of ~75 nm was measured by flow cell testing for 9 days, indicating elution of rhBMP-2 from the TiO2 nanotube arrays. For the in vivo study, the four groups of implants were placed into the proximal tibia of New Zealand White rabbits. In the implant group with TiO2 nanotube arrays and rhBMP-2, the bone-to-implant contact ratio was 29.5% and the bone volume ratio was 77.3%. Bone remodeling was observed not only in the periosteum but also in the interface between the bone and implant threads. These values were higher than in the machined surface, sandblasted large-grit and acid-etched surface, and TiO2 nanotube array surface groups. Our results suggest that TiO2 nanotube arrays could potentially be used as a reservoir for rhBMP-2 to reinforce osseointegration on the surface of dental implants.

  19. Improved osseointegration of dental titanium implants by TiO2 nanotube arrays with recombinant human bone morphogenetic protein-2: a pilot in vivo study

    PubMed Central

    Lee, Jae-Kwan; Choi, Dong-Soon; Jang, Insan; Choi, Won-Youl

    2015-01-01

    TiO2 nanotube arrays on the surface of dental implants were fabricated by two-step anodic oxidation. Their effects on bone-implant contact were researched by a pilot in vivo study. The implants were classified into four groups. An implant group with TiO2 nanotube arrays and recombinant human bone morphogenetic protein-2 (rhBMP-2) was compared with various surface implants, including machined surface, sandblasted large-grit and acid-etched surface, and TiO2 nanotube array surface groups. The diameter of the TiO2 nanotube window and TiO2 nanotube were ~70 nm and ~110 nm, respectively. The rhBMP-2 was loaded into TiO2 nanotube arrays and elution was detected by an interferometric biosensing method. A change in optical thickness of ~75 nm was measured by flow cell testing for 9 days, indicating elution of rhBMP-2 from the TiO2 nanotube arrays. For the in vivo study, the four groups of implants were placed into the proximal tibia of New Zealand White rabbits. In the implant group with TiO2 nanotube arrays and rhBMP-2, the bone-to-implant contact ratio was 29.5% and the bone volume ratio was 77.3%. Bone remodeling was observed not only in the periosteum but also in the interface between the bone and implant threads. These values were higher than in the machined surface, sandblasted large-grit and acid-etched surface, and TiO2 nanotube array surface groups. Our results suggest that TiO2 nanotube arrays could potentially be used as a reservoir for rhBMP-2 to reinforce osseointegration on the surface of dental implants. PMID:25709438

  20. Improved osseointegration of dental titanium implants by TiO2 nanotube arrays with recombinant human bone morphogenetic protein-2: a pilot in vivo study.

    PubMed

    Lee, Jae-Kwan; Choi, Dong-Soon; Jang, Insan; Choi, Won-Youl

    2015-01-01

    TiO2 nanotube arrays on the surface of dental implants were fabricated by two-step anodic oxidation. Their effects on bone-implant contact were researched by a pilot in vivo study. The implants were classified into four groups. An implant group with TiO2 nanotube arrays and recombinant human bone morphogenetic protein-2 (rhBMP-2) was compared with various surface implants, including machined surface, sandblasted large-grit and acid-etched surface, and TiO2 nanotube array surface groups. The diameter of the TiO2 nanotube window and TiO2 nanotube were ~70 nm and ~110 nm, respectively. The rhBMP-2 was loaded into TiO2 nanotube arrays and elution was detected by an interferometric biosensing method. A change in optical thickness of ~75 nm was measured by flow cell testing for 9 days, indicating elution of rhBMP-2 from the TiO2 nanotube arrays. For the in vivo study, the four groups of implants were placed into the proximal tibia of New Zealand White rabbits. In the implant group with TiO2 nanotube arrays and rhBMP-2, the bone-to-implant contact ratio was 29.5% and the bone volume ratio was 77.3%. Bone remodeling was observed not only in the periosteum but also in the interface between the bone and implant threads. These values were higher than in the machined surface, sandblasted large-grit and acid-etched surface, and TiO2 nanotube array surface groups. Our results suggest that TiO2 nanotube arrays could potentially be used as a reservoir for rhBMP-2 to reinforce osseointegration on the surface of dental implants. PMID:25709438

  1. 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.

  2. Visible-Light-Triggered Drug Release from TiO2 Nanotube Arrays: A Controllable Antibacterial Platform.

    PubMed

    Xu, Jingwen; Zhou, Xuemei; Gao, Zhida; Song, Yan-Yan; Schmuki, Patrik

    2016-01-11

    In this work, we use a double-layered stack of TiO2 nanotubes (TiNTs) to construct a visible-light-triggered drug delivery system. The key for visible light drug release is a hydrophobic cap on the nanotubes containing Au nanoparticles (AuNPs). The AuNPs allow for a photocatalytic scission of the hydrophobic chain under visible light. To demonstrate this principle, we loaded ampicillin (AMP) into the lower part of the TiO2 nanotube stack, triggered visible-light-induced release, and carried out antibacterial studies. The release from the platform becomes most controllable if the drug is silane-grafted in the hydrophilic bottom layer for drug storage. Thus, visible light photocatalysis can also determine the release kinetics of the active drug from the nanotube wall.

  3. Enhanced capacitance of composite TiO2 nanotube/boron-doped diamond electrodes studied by impedance spectroscopy.

    PubMed

    Siuzdak, K; Bogdanowicz, R; Sawczak, M; Sobaszek, M

    2015-01-14

    We report on novel composite nanostructures based on boron-doped diamond thin films grown on top of TiO2 nanotubes. The nanostructures made of BDD-modified titania nanotubes showed an increase in activity and performance when used as electrodes in electrochemical environments. The BDD thin films (∼200-500 nm) were deposited using microwave plasma assisted chemical vapor deposition (MW PA CVD) onto anodically fabricated TiO2 nanotube arrays. The influence of boron-doping level, methane admixture and growth time on the performance of the Ti/TiO2/BDD electrode was studied in detail. Scanning electron microscopy (SEM) was applied to investigate the surface morphology and grain size distribution. Moreover, the chemical composition of TiO2/BDD electrodes was investigated by means of micro-Raman spectroscopy. The composite electrodes TiO2/BDD are characterized by a significantly higher capacitive current compared to BDD films deposited directly onto a Ti substrate. The novel composite electrode of TiO2 nanotube arrays overgrown by boron-doped diamond (BDD) immersed in 0.1 M NaNO3 can deliver a specific capacitance of 2.10, 4.79, and 7.46 mF cm(-2) at a scan rate of 10 mV s(-1) for a [B]/[C] ratio of 2k, 5k and 10k, respectively. The substantial improvement of electrochemical performance and the excellent rate capability could be attributed to the synergistic effect of TiO2 treatment in CH4 : H2 plasma and the high electrical conductivity of BDD layers. The analysis of electrochemical impedance spectra using an electric equivalent circuit allowed us to determine the surface area on the basis of the value of constant phase element.

  4. Enhanced capacitance of composite TiO2 nanotube/boron-doped diamond electrodes studied by impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Siuzdak, K.; Bogdanowicz, R.; Sawczak, M.; Sobaszek, M.

    2014-12-01

    We report on novel composite nanostructures based on boron-doped diamond thin films grown on top of TiO2 nanotubes. The nanostructures made of BDD-modified titania nanotubes showed an increase in activity and performance when used as electrodes in electrochemical environments. The BDD thin films (~200-500 nm) were deposited using microwave plasma assisted chemical vapor deposition (MW PA CVD) onto anodically fabricated TiO2 nanotube arrays. The influence of boron-doping level, methane admixture and growth time on the performance of the Ti/TiO2/BDD electrode was studied in detail. Scanning electron microscopy (SEM) was applied to investigate the surface morphology and grain size distribution. Moreover, the chemical composition of TiO2/BDD electrodes was investigated by means of micro-Raman spectroscopy. The composite electrodes TiO2/BDD are characterized by a significantly higher capacitive current compared to BDD films deposited directly onto a Ti substrate. The novel composite electrode of TiO2 nanotube arrays overgrown by boron-doped diamond (BDD) immersed in 0.1 M NaNO3 can deliver a specific capacitance of 2.10, 4.79, and 7.46 mF cm-2 at a scan rate of 10 mV s-1 for a [B]/[C] ratio of 2k, 5k and 10k, respectively. The substantial improvement of electrochemical performance and the excellent rate capability could be attributed to the synergistic effect of TiO2 treatment in CH4 : H2 plasma and the high electrical conductivity of BDD layers. The analysis of electrochemical impedance spectra using an electric equivalent circuit allowed us to determine the surface area on the basis of the value of constant phase element.

  5. 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.

  6. Synthesis of transparent vertically aligned TiO2 nanotubes on a few-layer graphene (FLG) film.

    PubMed

    Cottineau, Thomas; Albrecht, Arnaud; Janowska, Izabela; Macher, Nicolas; Bégin, Dominique; Ledoux, Marc Jacques; Pronkin, Sergey; Savinova, Elena; Keller, Nicolas; Keller, Valérie; Pham-Huu, Cuong

    2012-01-30

    Novel transparent 1D-TiO(2)/few-layer graphene electrodes are realised by the anodic growth of vertically aligned TiO(2) nano-tubes on a few-layer graphene film coated on a glass substrate. PMID:22057023

  7. 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. PMID:27316743

  8. 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.

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

    PubMed Central

    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. PMID:25426006

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Self-organized TiO2 nanotube arrays in the photocatalytic degradation of methylene blue under UV light irradiation

    NASA Astrophysics Data System (ADS)

    Chung, Eun Hyuk; Baek, Seong Rim; Yu, Seong Mi; Kim, Jong Pil; Hong, Tae Eun; Kim, Hyun Gyu; Bae, Jong-Seong; Jeong, Euh Duck; Khan, F. Nawaz; Jung, Ok-sang

    2015-04-01

    Nanostructured titanium dioxide (NTiO2) is known to possess efficient photocatalytic activity and to have diverse applications in many fields due to its chemical stability, high surface area/volume ratio, high transmittance, and high refractive index in the visible and the near-ultraviolet regions. These facts prompted us to develop TiO2 nanotube (TiO2 NT) arrays through electrochemical anodic oxidation involving different electrolytes comprised of phosphoric acid — hydrofluoric acid aqueous systems by varying the voltage and the time. The annealing temperature of the nanotubes, TiO2 NTs, were varied to modify the surface morphology and were characterized by using X-ray diffraction and scanning electron microscopy. Scanning electron microscopy and X-ray diffraction results showed that the samples had uniform morphologies and good crystalline structures of the anatase phase at lower annealing temperatures and of the rutile phase at higher annealing temperatures. A secondary-ion mass-spectrometry analysis was used to investigate the surface atoms and to conduct a depth profile analysis of the TiO2 NTs. The efficiency of the photocatalytic activity of the TiO2 NT arrays in degrading methylene blue (MB) was investigated under UV-Vis light irradiation. The maximum photocatalytic activity was achieved for the samples with lower annealing temperatures due to their being in the anatase phase and having a higher surface area and a smaller crystal size, which play important roles in the degradation of organic pollutants.

  15. Preparation and characterisation of TiO2 nanoparticle and titanate nanotube obtained from Ti-salt flocculated sludge with drinking water and seawater.

    PubMed

    Kim, J H; Okour, Y; Yang, H S; Kim, J B; Shon, H K

    2011-02-01

    This study aimed to prepare and characterise titanium dioxide (TiO2) nanoparticles and titanate nanotubes produced from Ti-sat flocculated sludge with drinking water (DW) and seawater (SW). The Ti-salt flocculated sludge from DW and SW was incinerated at 600 degrees C to produce TiO2 nanoparticles. XRD results showed that the anatase TiO2 structure was predominant for TiO2 from DW (TiO2-DW) and TiO2 from SW (TiO2-SW), which were mainly doped with carbon atoms. Titanate nanotubes (tiNT) were obtained when TiO2-DW and TiO2-SW were hydrothermally treated with NaOH solution. Structure phase, shape, crystallisation and photocatalytic activity of tiNT were affected by the incineration temperature and the amount of sodium present in different tiNT. The tiNT doped with thiourea incinerated at 600 degrees C presented anatase phase, showing a high increase of the degree of crystallisation with nanotube-like structures. The photocatalytic activity of these photocatalysts was evaluated using photooxidation of gaseous acetaldehyde. Thiourea doped tiNT-DW and tiNT-SW showed similar photocatalytic activity compared to commercially available TiO2-P25 under UV light and indicated a photocatalytic activity under visible light. PMID:21456256

  16. Fabrication of bioactive, antibacterial TiO2 nanotube surfaces, coated with magnetron sputtered Ag nanostructures for dental applications.

    PubMed

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

    2014-10-01

    We investigated whether a silver coating on an anodic oxidized titania (TiO2) nanotube surface would be useful for preventing infections in dental implants. We used a magnetron sputtering process to deposit Ag nanoparticles onto a TiO2 surface. We studied different sputtering input power densities and maintained other parameters constant. We used scanning electron microscopy, X-ray diffraction, and contact angle measurements to characterize the coated surfaces. Staphylococcus aureus was used to evaluate antibacterial activity. The X-ray diffraction analysis showed peaks that corresponded to metallic Ag, Ti, O, and biocompatible anatase phase TiO2 on the examined surfaces. The contact angles of the Ag nanoparticle-loaded surfaces were significantly lower at 2.5 W/cm2 input power under pulsed direct current mode compared to commercial, untreated Ti surfaces. In vitro antibacterial analysis indicated that a significantly reduced number of S. aureus were detected on an Ag nanoparticle-loaded TiO2 nanotube surface compared to control untreated surfaces. No cytotoxicity was noted, except in the group treated with 5 W/cm2 input power density, which was the highest input of power density we tested for the magnetron sputtering process. Overall, we concluded that it was feasible to create antibacterial Ag nanoparticle-loaded titanium nanotube surfaces with magnetron sputtering. PMID:25942879

  17. Photoelectrochemical properties and the detection mechanism of Bi2WO6 nanosheet modified TiO2 nanotube arrays.

    PubMed

    Pang, Yajun; Xu, Guangqing; Zhang, Xu; Lv, Jun; Shi, Kai; Zhai, Pengbo; Xue, Qianyun; Wang, Xuedong; Wu, Yucheng

    2015-10-28

    Bi2WO6 nanosheet modified TiO2 nanotube arrays were synthesized by an anodization method combined with sequential chemical bath deposition for enhancement of the photoelectrochemical detection performance. The structures, morphologies and elemental compositions of the nanotube arrays were characterized with X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectrometry. Bi2WO6 nanosheets were successfully deposited on the tube walls of TiO2 nanotubes. The photoelectrochemical property of Bi2WO6/TiO2 NTAs was determined with chronoamperometry and cyclic voltammetry using an electrochemical workstation equipped with a UV LED light (365 nm). The optimum detection sensitivity of glucose in water was determined to be 0.244 μA mM(-1) in the linear range from 0 to 2500 μM. Bi2WO6 modification on TiO2 NTAs simultaneously decreased the background photocurrent and increased the current response to organics, resulting in the enhancement of photoelectrochemical detection properties. Mechanisms of the Bi2WO6 modification are discussed by analyzing the photoelectrochemical processes, including optical absorption, charges transfer and surface electrochemical reactions. Direct oxidation by holes rather than indirect oxidation by ˙OH radicals is believed to be a key role in this enhancement.

  18. Signal Amplification Strategy Based on TiO2-Nanotube Layers and Nanobeads Carrying Quantum Dots for Electrochemiluminescent Immunosensors

    PubMed Central

    Gao, Zhi-Da; Zhuang, Qian-Lan; Song, Yan-Yan; Lee, Kiyoung; Schmuki, Patrik

    2013-01-01

    Self-organized TiO2-nanotube layers can be used for immunoassay-type sensing in combination with amplifying CdTe labels in a direct and very sensitive electrochemiluminescent (ECL) configuration. Key properties for this method are the conductivity of the TiO2 nanotubes, and their transparency for light emitted from the CdTe labels at approximately 2.4 eV. To demonstrate the potential of this platform, we constructed a sandwich-type immunoassay onto the TiO2-nanotube wall with a layer of (3-aminopropyl)triethoxysilane as the cross-linker for antibody immobilization. For the counter part of the sandwich, we created an amplification system consisting of TiO2 nanobeads carrying the secondary antibody and multiple CdTe quantum dots (multiQD). For antigen (IgG) detection, we find that this combination of 3D transparent electrode with multiQD labels allows for an ECL detection limit of 0.05 pg mL−1 and a linearity of the signal in the range of 0.1–108 pg mL−1. PMID:24551545

  19. 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.

  20. 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.

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

    PubMed

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

    2014-08-01

    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. PMID:24971593

  2. 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.

  3. Local delivery of antimicrobial peptides using self-organized TiO2 nanotube arrays for peri-implant infections.

    PubMed

    Ma, Menghan; Kazemzadeh-Narbat, Mehdi; Hui, Yu; Lu, Shanshan; Ding, Chuanfan; Chen, David D Y; Hancock, Robert E W; Wang, Rizhi

    2012-02-01

    Peri-implant infections have been reported as one of the major complications that lead to the failure of orthopedic implants. An ideal solution to the peri-implant infection is to locally deliver antimicrobial agents through the implant surface. The rising problem of infections caused by multiple antibiotic-resistant bacteria makes traditional antibiotics less desirable for the prevention of peri-implant infections. One of the promising alternatives is the family of antimicrobial peptides (AMPs). In this study, we report the local delivery of AMPs through the nanotubular structure processed on titanium surface. Self-organized and vertically oriented TiO2 nanotubes, about 80 nm in diameter and 7 μm thick, were prepared by the anodization technique. HHC-36 (KRWWKWWRR), one of the most potent broad-spectrum AMPs, was loaded onto the TiO2 nanotubes via a simple vacuum-assisted physical adsorption method. Antimicrobial activity testing against Gram-positive bacterium, Staphylococcus aureus, demonstrated that this AMP-loaded nanotubular surface could effectively kill the bacteria (≈ 99.9% killing) and reduce the total bacterial number adhered to the surface after 4 h of culture. In vitro AMP elution from the nanotubes was investigated using liquid chromatography-mass spectrometry (LC-MS). The release profiles strongly depended on the crystallinity of the TiO2 nanotubes. Anatase TiO2 nanotubes released significantly higher amounts of AMP than amorphous nanotubes during the initial burst release stage. Both followed almost the same slow release profile from 4 h up to 7 days. Despite the differences in release kinetics, no significant difference was observed between these two groups in bactericidal efficiency. PMID:22045618

  4. 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.

  5. Polydopamine-Coated TiO2 Nanotubes for Selective Photocatalytic Oxidation of Benzyl Alcohol to Benzaldehyde Under Visible Light.

    PubMed

    Tripathy, Jyotsna; Loget, Gabriel; Altomare, Marco; Schmuki, Patrik

    2016-05-01

    TiO2 nanotube arrays grown by anodization were coated with thin layers of polydopamine as visible light sensitizer. The PDA-coated TiO2 scaffolds were used as photocatalyst for selective oxidation of benzyl alcohol under monochromatic irradiation at 473 nm. Benzaldehyde was selectively formed and no by-products could be detected. A maximized reaction yield was obtained in O2-saturated acetonitrile. A mechanism is proposed that implies firstly the charge carrier generation in polydopamine as a consequence of visible light absorption. Secondly, photo-promoted electrons are injected in TiO2 conduction band, and subsequently transferred to dissolved O2 to form O*2- radicals. These radicals react with benzyl alcohol and lead to its selective dehydrogenation oxidation towards benzaldehyde. PMID:27483930

  6. Polydopamine-Coated TiO2 Nanotubes for Selective Photocatalytic Oxidation of Benzyl Alcohol to Benzaldehyde Under Visible Light.

    PubMed

    Tripathy, Jyotsna; Loget, Gabriel; Altomare, Marco; Schmuki, Patrik

    2016-05-01

    TiO2 nanotube arrays grown by anodization were coated with thin layers of polydopamine as visible light sensitizer. The PDA-coated TiO2 scaffolds were used as photocatalyst for selective oxidation of benzyl alcohol under monochromatic irradiation at 473 nm. Benzaldehyde was selectively formed and no by-products could be detected. A maximized reaction yield was obtained in O2-saturated acetonitrile. A mechanism is proposed that implies firstly the charge carrier generation in polydopamine as a consequence of visible light absorption. Secondly, photo-promoted electrons are injected in TiO2 conduction band, and subsequently transferred to dissolved O2 to form O*2- radicals. These radicals react with benzyl alcohol and lead to its selective dehydrogenation oxidation towards benzaldehyde.

  7. A comparison of TiO2 nanoparticles and nanotubes for catalytic gas phase destruction of H2S gas at high temperatures.

    PubMed

    Shahzad, Naeem; Hussain, Syed Tajammul; Siddiqua, Asima; Baig, Muhammad Anwar

    2012-06-01

    Reduction of H2S gas over Sulphur doped TiO2 nanoparticles and TiO2 nanotubes was studied in this work. Fixed bed catalytic system was used for the catalytic reduction of H2S gas at a high temperature of 450 degrees C under laboratory conditions. 99.97% reduction was achieved using S-doped TiO2. 2.89% Sulphur was adsorbed on S-doped TiO2 nanoparticles in the form of Ti(SO4)2, while 95.6% reduction was achieved in case of TiO2 nanotubes and the sulphur adsorption was 2.67%. The XRD, SEM, and EDX techniques were carried out to characterize the nanoparticles and nanotubes, while gas reduction analysis was carried out using GC-MS for gas samples. PMID:22905577

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

    PubMed

    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.

  9. 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.

  10. 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

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

    PubMed

    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. PMID:27576914

  12. Dye-sensitized solar cells based on anatase TiO 2 hollow spheres/carbon nanotube composite films

    NASA Astrophysics Data System (ADS)

    Yu, Jiaguo; Fan, Jiajie; Cheng, Bei

    Dye-sensitized solar cells (DSSCs) based on anatase TiO 2 hollow spheres (TiO2HS)/multi-walled carbon nanotubes (CNT) nanocomposite films are prepared by a directly mechanical mixing and doctor blade method. The prepared samples are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV-vis absorption spectroscopy and N 2 adsorption-desorption isotherms. The photoelectric conversion performances of the DSSCs based on TiO2HS/CNT composite film electrodes are also compared with commercial-grade Degussa P25 TiO 2 nanoparticles (P25)/CNT composite solar cells at the same film thickness. The results indicate that the photoelectric conversion efficiencies (η) of the TiO2HS/CNT composite DSSCs are dependent on CNT loading in the electrodes. A small amount of CNT clearly enhances DSSC efficiency, while excessive CNT loading significantly lowers their performance. The former is because CNT enhance the transport of electrons from the films to FTO substrates. The latter is due to high CNT loading shielding the visible light from being adsorbed by dyes.

  13. Stabilizing of the Transitory Species (TiO2)2 by Encapsulation Into Carbon Nanotubes.

    PubMed

    Dargouthi, Sarra; Boughdiri, Salima; Tangour, Bahoueddine

    2015-01-01

    The aim of this paper is studying the encapsulation effect of carbon nanotubes (CNTs ) on the stabilizing process of titanium dioxide molecule dimers (TiO2)2. First, a theoretical study was performed concerning the guest species that are various titanium dioxide dimers. Five structures were treated as following: i) Cis (C) or ii)Trans (T) relatively to a square shaped fragment Ti2O2, iii) a mixed Tetrahedral/Pyramidal (T/P) disposition while two titanium atoms are sharing three oxygen atoms, and finally not bonded dimers in iv) parallel (P) and v) orthogonal (O) positions respectively. Only the (T), (C) and (T/P) isomers may be considered as stable compounds. The structure of the T-dimer is more stable than the Cis one by only 6.5 kcal mol-1. Typically, intra and extracyclic Ti-O bond lengths are 1.84Å and 1.61Å respectively. (T/P) dimer can be described as a metastable structure since its energy is higher than (T) one by 19 kcal mol-1. NBO analysis highlights the participation of dative bonding between oxygen lone pair and vacant titanium 3d orbitals. (P) and (O) structures represent transitory species that transform into the more stable structure which is the T-dimer. The second and principal part of this work concerns the re-optimization of the studied structures placed inside the CNT (12,0). Only (T), (C) and (P) dimers are stabilized by encapsulation through the establishment of strong interactions with the CNT wall. The (T / P) and (O) isomers which are converted into (T) and (P) dimers respectively, are leaving the nanotube while they still interacting with its edge. These favorable results are indicating in one hand the possibly detection of (T) and (C) isomers, and in another hand that the process of polymerization of the TiO2 molecule which is leading to nanostructured materials could be controlled by encapsulation within the CNTs. PMID:26085429

  14. Photocatalysis-triggered ion rectification in artificial nanochannels based on chemically modified asymmetric TiO2 nanotubes.

    PubMed

    Hu, Ziying; Zhang, Qianqian; Gao, Jun; Liu, Zhaoyue; Zhai, Jin; Jiang, Lei

    2013-04-16

    Ion rectification is one of the important characteristics of biological ion channels. Inspired by the function of biological ion channels, creation of artificial nanochannels that show analogous ion rectification characteristics has attracted a great interest recently. Herein, we demonstrate a new type of artificial solid-state nanochannel with ion rectification characteristics. The creation of artificial nanochannels includes the formation of asymmetric TiO2 nanotubes by electrochemical anodization of Ti metal, followed by chemical modification with octadecyltrimethoxysilane (OTS) molecules. The carboxylic groups are introduced onto the tip side of TiO2 nanotubes via photocatalytic decomposition of OTS molecules by TiO2 photocatalysis under ultraviolet light. When the radius of tip side of TiO2 nanotubular channels is comparable to the thickness of electric double layer, the negatively charged surface in neutral electrolyte in combination with the asymmetric pore geometry contributes to the ion rectification characteristics. Compared with previous artificial nanochannels, our new type of artificial nanochannel is more facile to fabricate and behaves as a diode that rectifies the ion transport, which also shows some other potential applications, such as sensor and separation materials.

  15. 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.

  16. Improved conversion efficiency of Ag2S quantum dot-sensitized solar cells based on TiO2 nanotubes with a ZnO recombination barrier layer

    PubMed Central

    2011-01-01

    We improve the conversion efficiency of Ag2S quantum dot (QD)-sensitized TiO2 nanotube-array electrodes by chemically depositing ZnO recombination barrier layer on plain TiO2 nanotube-array electrodes. The optical properties, structural properties, compositional analysis, and photoelectrochemistry properties of prepared electrodes have been investigated. It is found that for the prepared electrodes, with increasing the cycles of Ag2S deposition, the photocurrent density and the conversion efficiency increase. In addition, as compared to the Ag2S QD-sensitized TiO2 nanotube-array electrode without the ZnO layers, the conversion efficiency of the electrode with the ZnO layers increases significantly due to the formation of efficient recombination layer between the TiO2 nanotube array and electrolyte. PMID:21777458

  17. 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.

  18. Electrochemical immunosensor constructed using TiO2 nanotubes as immobilization scaffold and tracing tag.

    PubMed

    Huo, Xiaohe; Liu, Peipei; Zhu, Jie; Liu, Xiaoqiang; Ju, Huangxian

    2016-11-15

    A ternary TiO2 nanotube (TNT) composite and a signal antibody and horseradish peroxidase (HRP) functionalized TNT were designed as an electrode scaffold for immobilization of high quantity of capture antibody and a tracing tag for immunosensing, respectively. The polyaniline (PANI) was coated on TNTs by chemical oxidative polymerization, and gold nanoparticles were deposited on TNT-PANI with a routine chemical reduction. Various techniques including scanning electron microscopy, energy dispersive X-ray, transmission electron microscope, X-ray diffraction, Fourier transform infrared spectra, X-ray photoelectron spectra, impedance and electrochemical techniques were used to characterize the nano-materials. Using bis(sulfosuccinimidyl) suberate as amino cross-linker, the TNT composite could be further functionalized with protein G' for oriented immobilization of capture antibody on electrode surface. Upon sandwich-type immunoreaction, the signal antibody on the tracing tag was quantitatively captured on the surface to generate sensitive electrochemical response with a H2O2 mediated HRP catalytic reaction. With α-fetoprotein as an analyte model, the immunosensor showed a linear range of 0.01-350ngmL(-1) with a detection limit of 1.5pgmL(-1). The accelerated electron transfer by the ternary composite, oriented immobilization of capture antibody and high loading of HRP on the TNT tracing tag greatly amplified the electrochemical signal, and led to the superior performance of the immunoassay.

  19. Electrochemical immunosensor constructed using TiO2 nanotubes as immobilization scaffold and tracing tag.

    PubMed

    Huo, Xiaohe; Liu, Peipei; Zhu, Jie; Liu, Xiaoqiang; Ju, Huangxian

    2016-11-15

    A ternary TiO2 nanotube (TNT) composite and a signal antibody and horseradish peroxidase (HRP) functionalized TNT were designed as an electrode scaffold for immobilization of high quantity of capture antibody and a tracing tag for immunosensing, respectively. The polyaniline (PANI) was coated on TNTs by chemical oxidative polymerization, and gold nanoparticles were deposited on TNT-PANI with a routine chemical reduction. Various techniques including scanning electron microscopy, energy dispersive X-ray, transmission electron microscope, X-ray diffraction, Fourier transform infrared spectra, X-ray photoelectron spectra, impedance and electrochemical techniques were used to characterize the nano-materials. Using bis(sulfosuccinimidyl) suberate as amino cross-linker, the TNT composite could be further functionalized with protein G' for oriented immobilization of capture antibody on electrode surface. Upon sandwich-type immunoreaction, the signal antibody on the tracing tag was quantitatively captured on the surface to generate sensitive electrochemical response with a H2O2 mediated HRP catalytic reaction. With α-fetoprotein as an analyte model, the immunosensor showed a linear range of 0.01-350ngmL(-1) with a detection limit of 1.5pgmL(-1). The accelerated electron transfer by the ternary composite, oriented immobilization of capture antibody and high loading of HRP on the TNT tracing tag greatly amplified the electrochemical signal, and led to the superior performance of the immunoassay. PMID:27261885

  20. 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.

  1. 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

  2. TiO2 Nanotubes of Enhanced Nanocrystallinity and Well-Preserved Nanostructure by Pre-Annealing and Post-Hydrothermal Treatments

    NASA Astrophysics Data System (ADS)

    Yuwono, Akhmad Herman; Ferdiansyah, Alfian; Sofyan, Nofrijon; Kartini, Indriana; Pujianto, Tego Hadi

    2011-12-01

    In the current investigation, a modified process combining pre-annealing and post-hydrothermal treatments has been applied on the as-dried TiO2 nanotubes derived from alkaline route of TiO2 P25 nanoparticles in 10 M NaOH solution. The combined treatment is purposely aimed at enhancing the nanocrystallinity of anatase TiO2, while at the same time maintaining the integrity of the nanotube hollow structures. The detail of the structure, morphology and crystallinity of the resulting nanotubes were examined by XRD, SEM and TEM, while the optical properties of nanotubes were investigated by UV-visible spectroscopy. For the nanotube samples which have been previously annealed at 300 °C, the crystallite size of anatase TiO2 in nanotubes increased from 17.20 to 18.30 nm after being subjected to post-hydrothermal treatment at 100 to 150 °C. The band gap energy (Eg) of the resulting nanotubes is inversely proportional to the crystallite size of anatase phase where the lowest value of 3.21 eV was obtained from the TiO2 nanotube sample with the biggest crystallite size of 18.30 nm.

  3. Fabrication of plasmonic AgBr/Ag nanoparticles-sensitized TiO2 nanotube arrays and their enhanced photo-conversion and photoelectrocatalytic properties

    NASA Astrophysics Data System (ADS)

    Wang, Qingyao; Qiao, Jianlei; Jin, Rencheng; Xu, Xiaohui; Gao, Shanmin

    2015-03-01

    Plasmonic photosensitizer AgBr/Ag nanospheres supported on TiO2 nanotube arrays (TiO2 NTs) are prepared by successive ionic layer adsorption and reaction (SILAR) technique followed by photoreduction methods. The structural and surface morphological properties of AgBr/Ag nanoparticles sensitized TiO2 NTs and their photoelectrochemical performance are investigated and discussed. A detailed formation mechanism of the TiO2 NTs/AgBr/Ag is proposed. The TiO2 NTs/AgBr/Ag exhibit excellent photocurrent and photoelectrocatalytic activities under visible light irradiation. Efficient utilization of solar energy to create electron-hole pairs is attributed to the significant visible light response and surface plasmon resonance of Ag nanoparticles. This finding indicates that the high photosensitivity of the TiO2 NTs-based surface plasmon resonance materials could be applied toward the development of new plasmonic visible-light-sensitive photovoltaic fuel cells and photocatalysts.

  4. 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.

  5. Development of nano TiO2-incorporated phosphate coatings on hot dip zinc surface for good paintability and corrosion resistance

    NASA Astrophysics Data System (ADS)

    Shibli, S. M. A.; Chacko, Francis

    2011-01-01

    Phosphating is one of the most important chemical conversion processes for the purpose of corrosion protection and primer for painting. In the present work, nano TiO2 incorporated phosphate coating was developed on hot dip galvanized zinc surface for achieving good paintability and corrosion resistance. Based on the results from preliminary studies, the amount of nano TiO2 incorporated into the phosphating bath was optimized as 0.1 g. TiO2 incorporation effectively reduced the extent of zinc dissolution during phosphating and activated the process to achieve the expected coating weight faster. Also it yielded coating with greater thickness than the normal phosphate coating. The TiO2 incorporation resulted in a well crystallized phosphate coating with large crystal size and greater surface coverage. Results from the electrochemical analysis revealed the better barrier protection characteristics and enhanced corrosion resistance of TiO2 incorporated phosphate coatings over the normal phosphate coatings.

  6. 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.

  7. TiO2 nanotube membranes on transparent conducting glass for high efficiency dye-sensitized solar cells.

    PubMed

    Dubey, Mukul; Shrestha, Maheshwar; Zhong, Yihan; Galipeau, David; He, Hongshan

    2011-07-15

    Crack-free TiO(2) nanotube (NT) membranes were obtained by short time re-anodization of a sintered TiO(2) NT array on Ti foil, followed by dilute HF etching at room temperature. The resulting freestanding TiO(2) membranes were opaque with a slight yellow color having one end open and another end closed. The membranes were then fixed on transparent fluorine-tin-oxide glass using a thin layer of screen-printed TiO(2) nanoparticles (NPs) as a binding medium. It was found that low temperature treatment of the resulting NT/NP film under appropriate pressure before sintering at 450 °C was critical for successful fixation of the NT membrane on the NP layer. The resulting films with open-ends of NT membranes facing the NP layer (open-ends down, OED, configuration) exhibited better interfacial contact between NTs and NPs than those with closed-ends facing the NP layer (closed-ends down, CED, configuration). The cells with an OED configuration exhibit higher external quantum efficiency, greater charge transfer resistance from FTO/TiO(2) to electrolyte, and better dye loading compared to CED configurations. The solar cells with the OED configuration gave 6.1% energy conversion efficiency under AM1.5G condition when the commercial N719 was used as a dye and I(-)/I(3)(-) as a redox couple, showing the promise of this method for high efficiency solar cells.

  8. In situ controlled growth of well-dispersed gold nanoparticles in TiO2 nanotube arrays as recyclable substrates for surface-enhanced Raman scattering.

    PubMed

    Chen, Yajie; Tian, Guohui; Pan, Kai; Tian, Chungui; Zhou, Juan; Zhou, Wei; Ren, Zhiyu; Fu, Honggang

    2012-01-21

    In this paper, well-aligned Au-decorated TiO(2) nanotube arrays with high surface-enhanced Raman scattering (SERS) enhancement were prepared using a facile in situ reduction and controlled growth approach. The gold nanoparticles are well-dispersed and assembled on the mouth surface and the inside of the TiO(2) nanotubes without clogging. The structure and optical properties of the Au-decorated TiO(2) nanotube arrays have been characterized. The Au-decorated TiO(2) nanotube arrays were employed as SERS-active substrates, which exhibit good performance due to long-range coupling between Au nanoparticles, and TiO(2)-assisted enhanced charge-transfer from Au to Rh6G. The SERS activity of the substrates strongly depends on the crystallite size and level of aggregation. The substrates display significant fluorescence quenching ability and uniform SERS responses throughout the whole surface area. Particularly, good recyclability is shown. The photocatalytic property of Au-decorated TiO(2) nanotube array was exploited to recycle the substrate through UV light photocatalytic purification. The experimental results showed that the substrate is featured by high reproducibility and can be used as a highly efficient SERS substrate for multiple detection of different chemical and biological molecules.

  9. 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

    2016-06-01

    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. PMID:27169417

  10. 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

    2016-06-01

    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.

  11. TiO2 particles on a 3D network of single-walled nanotubes for NH3 gas sensors.

    PubMed

    Jo, Yong Deok; Lee, Sooken; Seo, Jeongeun; Lee, Soobum; Ann, Doyeon; Lee, Haiwon

    2014-12-01

    Ammonia (NH3) gas is one of the gases which causes damage to environment such as acidification and climate change. In this study, a gas sensor based on the three-dimensional (3D) network of single-walled nanotubes (SWNTs) was fabricated for the detection of NH3 gas in dry air. The sensor showed enhanced performance due to the fast gas diffusion rate and weak interactions between the carbon nanotubes and the substrate. Metal oxide particles were introduced to enhance the performance of the gas sensor. Atomic layer deposition (ALD) was employed to deposit the metal oxide in the complex structure, and good control over thickness was achieved. The hybrid gas sensor consisting of the 3D network of SWNTs with anatase TiO2 particles showed stable, repeatable, and enhanced gas sensor performance. The phase of TiO2 particles was characterized by Raman and the morphology of the TiO2 particles on the 3D network of SWNTs was analyzed by transmission electron microscope.

  12. Photoelectrocatalytic Inactivation of E. coli by ZnSe/CdS Co-sensitized TiO2 Nanotube Array.

    PubMed

    Zou, Jianmei; Nguyen, VanManh; Yin, Xuehua; Wu, Zeming; Cai, Qingyun

    2016-01-01

    A step-wise structural ZnSe/CdS co-sensitized TiO2 nanotube (NT) electrode was prepared by pulse-electrodeposition and successive ionic layer adsorption and reaction (SILAR), with an aim towards enhancing the absorption efficiency of TiO2 NTs in visible light region and enhancing the photo-electrical transform efficiency. The as-prepared CdS/ZnSe/TiO2 NTs were applied to the photoelectrocatalytic inactivation of E. coli. A complete inactivation of 3.0 × 10(8) cfu mL(-1) E. coli was observed after 60 min of photoelectrocatalysis process under the illumination of visble light. PMID:27302579

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    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.

  14. 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.

  15. Ag nanoparticle-deposited TiO2 nanotube arrays for electrodes of Dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kawamura, Go; Ohmi, Hayato; Tan, Wai Kian; Lockman, Zainovia; Muto, Hiroyuki; Matsuda, Atsunori

    2015-05-01

    Dye-sensitized solar cells composed of a photoanode of Ag nanoparticle (NP)-deposited TiO2 nanotube (TNT) arrays were fabricated. The TNT arrays were prepared by anodizing Ti films on fluorine-doped tin oxide (FTO)-coated glass substrates. Efficient charge transportation through the ordered nanostructure of TNT arrays should be carried out compared to conventional particulate TiO2 electrodes. However, it has been a big challenge to grow TNT arrays on FTO glass substrates with the lengths needed for sufficient light-harvesting (tens of micrometers). In this work, we deposited Ag nanoparticles (NPs) on the wall of TNT arrays to enhance light-harvesting property. Dye-sensitized solar cells with these Ag NP-deposited TNT arrays yielded a higher power conversion efficiency (2.03 %) than those without Ag NPs (1.39 %).

  16. 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.

  17. SnO2@TiO2 double-shell nanotubes for a lithium ion battery anode with excellent high rate cyclability.

    PubMed

    Jeun, Jeong-Hoon; Park, Kyu-Young; Kim, Dai-Hong; Kim, Won-Sik; Kim, Hong-Chan; Lee, Byoung-Sun; Kim, Honggu; Yu, Woong-Ryeol; Kang, Kisuk; Hong, Seong-Hyeon

    2013-09-21

    SnO2@TiO2 double-shell nanotubes have been facilely synthesized by atomic layer deposition (ALD) using electrospun PAN nanofibers as templates. The double-shell nanotubes exhibited excellent high rate cyclability for lithium ion batteries. The retention of hollow structures during cycling was demonstrated.

  18. 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.

  19. Controlled morphology modulation of anodic TiO2 nanotubes via changing the composition of organic electrolytes.

    PubMed

    Guo, Zhengkai; Li, Xuemin; Zhang, Xuehua; Guan, Zishen; He, Tao

    2014-06-21

    Titanium dioxide (TiO2) nanotubes are prepared by electrochemical anodization using Ti metal foils under a DC bias of 30 V for 20 h. The electrolyte is a mixture of formamide (FA) and ethylene glycol (EG), which contains NH4F (0.3 wt%) and H2O (2.0 v%). The diameter and wall thickness of the nanotubes decrease with the increase of EG content, while the length first decreases with the increase of EG content and then increases again. An O-ring-like pattern is formed on the outer surface of TiO2 nanotubes upon the introduction of FA into the EG electrolyte, upon which the surface becomes rougher and rougher with increasing FA content. This is caused by the breaking and re-establishment of a double layer at the interface. All of the observed phenomena are closely related to the conductivity and viscosity of the electrolyte as well as the formation of hydrogen bond in the system. The proposed mechanism is confirmed by introducing hydroxyl ions into the pure EG electrolyte. PMID:24802504

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

    PubMed Central

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

    2014-01-01

    Nanostructured surface geometries have been the focus of a multitude of recent biomaterials 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. PMID:24582257

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

    PubMed

    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

  2. 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

  3. Fluorescent Carbon Quantum Dots Incorporated into Dye-Sensitized TiO2 Photoanodes with Dual Contributions.

    PubMed

    Shi, Yan; Na, Yong; Su, Ting; Li, Liang; Yu, Jia; Fan, Ruiqing; Yang, Yulin

    2016-06-22

    Fluorescent carbon quantum dots (CQDs) were prepared through bottom-up synthesis, which possess excitation wavelength-dependent photoluminescence properties upon excitation by near visible light. For the first time, CQDs were incorporated into N719-sensitized TiO2 photoelectrodes as the electron-transport medium, presenting dual contributions to the photo-to-electrical energy conversion: 1) spectral response compensation for the dye-sensitized TiO2 film at around 400 nm was successfully observed in the incident photon-to-current conversion measurements; and 2) intensity modulated photocurrent/photovoltage spectroscopy showed that the electron transport time, charge collection efficiency, and electron diffusion length in the TiO2 electrode were all improved after CQDs incorporation. An example of using the CQDs- containing photoanode in a solar cell device resulted in enhancements of 32 % and 21 % for the short-circuit current density and photo-to-electrical conversion efficiency, respectively. PMID:27218888

  4. 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

  5. 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

  6. 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

  7. 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

  8. Fabrication and performance evaluation of hybrid supercapacitor electrodes based on carbon nanotubes and sputtered TiO2.

    PubMed

    Aravinda, L S; Nagaraja, K K; Nagaraja, H S; Bhat, K Udaya; Bhat, B Ramachandra

    2016-08-01

    We report a simple and eco-friendly method for the fabrication of a titanium dioxide/functionalized multiwalled carbon nanotube (TiO2/FMWCNT) composite electrode for use in supercapacitors. The nanocomposite electrodes were formed by depositing titanium dioxide onto FMWCNTs using reactive magnetron sputtering, thus providing a green roue for the formation of the binder-free composite electrode. It is shown that the electrochemical performance of the fabricated electrodes can be altered by tuning the thickness of the titanium dioxide overlayer. The integrated nanocomposite electrode showed an improved specific capacitance of 90 Fg(-1) in two-electrode configuration. PMID:27334299

  9. Fabrication and performance evaluation of hybrid supercapacitor electrodes based on carbon nanotubes and sputtered TiO2

    NASA Astrophysics Data System (ADS)

    Aravinda, L. S.; Nagaraja, K. K.; Nagaraja, H. S.; Udaya Bhat, K.; Ramachandra Bhat, B.

    2016-08-01

    We report a simple and eco-friendly method for the fabrication of a titanium dioxide/functionalized multiwalled carbon nanotube (TiO2/FMWCNT) composite electrode for use in supercapacitors. The nanocomposite electrodes were formed by depositing titanium dioxide onto FMWCNTs using reactive magnetron sputtering, thus providing a green roue for the formation of the binder-free composite electrode. It is shown that the electrochemical performance of the fabricated electrodes can be altered by tuning the thickness of the titanium dioxide overlayer. The integrated nanocomposite electrode showed an improved specific capacitance of 90 Fg-1 in two-electrode configuration.

  10. Fabrication and performance evaluation of hybrid supercapacitor electrodes based on carbon nanotubes and sputtered TiO2

    NASA Astrophysics Data System (ADS)

    Aravinda, L. S.; Nagaraja, K. K.; Nagaraja, H. S.; Udaya Bhat, K.; Ramachandra Bhat, B.

    2016-08-01

    We report a simple and eco-friendly method for the fabrication of a titanium dioxide/functionalized multiwalled carbon nanotube (TiO2/FMWCNT) composite electrode for use in supercapacitors. The nanocomposite electrodes were formed by depositing titanium dioxide onto FMWCNTs using reactive magnetron sputtering, thus providing a green roue for the formation of the binder-free composite electrode. It is shown that the electrochemical performance of the fabricated electrodes can be altered by tuning the thickness of the titanium dioxide overlayer. The integrated nanocomposite electrode showed an improved specific capacitance of 90 Fg‑1 in two-electrode configuration.

  11. Synthesis and photoinduced charge-transfer properties of a ZnFe2O4-sensitized TiO2 nanotube array electrode.

    PubMed

    Li, Xinyong; Hou, Yang; Zhao, Qidong; Chen, Guohua

    2011-03-15

    TiO2 nanotube arrays sensitized with ZnFe2O4 nano-crystals were successfully fabricated by a two-step process of anodization and a vacuum-assistant impregnation method followed by annealing. The sample was studied by an environmental scanning electron microscope, a transmission electron microscope, energy-dispersive X-ray analysis, and X-ray diffraction to characterize its morphology and chemical composition. Ultraviolet-visible (UV-vis) absorption spectra and a photoelectrochemical measurement approved that the ZnFe2O4 sensitization enhanced the probability of photoinduced charge separation and extended the range of the photoresponse of TiO2 nanotube arrays from the UV to visible region. In addition, the behaviors of photoinduced charge transfer in a TiO2 nanotube array electrode before and after sensitization by ZnFe2O4 nanocrystals were comparatively studied. The photoluminescence of the TiO2 nanotube array electrode became suppressed, and the surface photovoltage responses on the spectrum were significantly enhanced after the introduction of ZnFe2O4 nanocrystals. The transfer dynamics of the photoinduced charges were observed directly by a transient photovoltage measurement, which revealed a fast charge separation at the interface between ZnFe2O4 nanocrystals and TiO2 nanotubes upon light excitation.

  12. 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.

  13. 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. PMID:27509326

  14. Formation of TiO2 nanotube arrays in KOH added fluoride-ethylene glycol (EG) electrolyte and its photoelectrochemical response

    NASA Astrophysics Data System (ADS)

    Nyein, Nyein; Lockman, Zainovia; Matsuda, Astunori; Kawamura, Go; Tan, Wai Kian; Oo, Than Zaw

    2016-07-01

    In this study, highly ordered TiO2 nanotube arrays were prepared by anodic oxidation of titanium foil in fluoride -EG electrolyte containing a small amount of potassium hydroxide, KOH at 60 V for 30 min. This electrolyte resulted in the formation of long nanotubes with an average length of 10 µm and diameter of 170 nm. For comparison, TiO2 nanotubes anodized in H2O added EG electrolyte which produces short nanotubes with an average tube length of 5 µm and diameter of 170 nm. It appears that the addition of KOH into the fluoride EG electrolyte accelerated the formation of the TiO2 nanotubes as it is believed that the chemical dissolution at the tips of the nanotubes is suppressed. Highly ordered TiO2 nanotubes anodized in KOH added EG electrolyte exhibited the photocurrent density of 2 mA/cm2, which is significantly higher than H2O added sample (1.5 mA/cm2).

  15. Preparation of TiO2/multiwalled carbon nanotube composites and their applications in photocatalytic reduction of Cr(VI) study.

    PubMed

    Tan, Xiaoli; Fang, Ming; Wang, Xiangke

    2008-11-01

    The TiO2/multiwalled carbon nanotube (MWCNT) composites were prepared by hydrothermal deposition. Batch experiments were carried out to study the removal of Cr(VI) from aqueous solution to TiO2, MWCNTs and TiO2/MWCNTs. Scanning electron microscopy and X-ray diffraction were utilized to characterize the prepared TiO2/MWCNT composites. The introduction of MWCNTs onto TiO2 catalyst led to a remarkable increase of Cr(VI) removal through adsorption and photocatalytic reduction under ultraviolet irradiation. Results of X-ray photoelectron spectroscopy analysis of chromium species adsorbed on TiO2/MWCNTs phase revealed that the removal mechanism of Cr(VI) by TiO2/MWCNTs under UV-irradiation was the reduction of Cr(VI) into Cr(III). The adsorption and photocatalytic activity of Cr(VI) decreased with increasing in pH, and was not affected by the concentration of sulphate obviously. In the ternary systems humic acid (HA)/fulvic acid (FA)-Cr(VI)-TiO2/MWCNTs, the increasing of FA/HA concentration did not cause any drastic changes in the adsorption capacity in terms of Cr(VI) concentration in the dark, but a minor increasing trend for the photocatalytic reduction of Cr(VI). The presence of humic substances enhanced the photocatalytic reduction and adsorption of Cr(III) to TiO2/MWCNTs.

  16. 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

    2012-05-01

    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.

  17. TiO2 Nanotubes/MWCNTs Nanocomposite Photocatalysts: Synthesis, Characterization and Photocatalytic Hydrogen Evolution Under UV-Vis Light Illumination

    SciTech Connect

    Li, Hao-Peng; Zhang, Xiao-Yan; Cui, Xiao-Li; Lin, Yuehe

    2012-03-01

    Nanocomposite of TiO2 nanotubes (TiO2NTs) and multiwalled carbon nanotubes (MWCNTs) has been synthesized by a hydrothermal method and firstly used in photocatalytic hydrogen production. The obtained TiO2 NTs/MWCNTs composites were characterized by X-ray diffraction, transmission electron microscopy, Raman spectrum and ultraviolet-visible diffuse reflectance spectroscopy. The experimental results revealed that the MWCNTs were decorated with well dispersed anatase TiO2 nanotubes with a diameter of 8-15 nm. A slight blue shift and weak symmetry was observed for the strongest Raman peak which resulted from strain gradients originating from interface integration between TiO2 nanotubes and MWCNTs. The photocatalytic activity of the as-prepared samples was evaluated by hydrogen evolution from water splitting using Na2S and Na2SO3 as sacrificial reagents under UV-vis light irradiation. Enhanced photocatalytic activity compared with P25 has been observed for the resulted samples. The nanocomposite with optimized MWCNTs content of 1% displayed a hydrogen production rate of 161 u mol/h/g. Good photocatalytic stability of the as-synthesized samples was observed as well.

  18. 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.

  19. Conveniently fabricated heterojunction ZnO/TiO2 electrodes using TiO2 nanotube arrays for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Liu, Rui; Yang, Wein-Duo; Qiang, Liang-Sheng; Liu, Hsin-Yi

    2012-12-01

    TiO2 nanotube arrays with an inner average pore diameter of 83 nm and a length of 14 μm are grown on Ti foils by electrochemical anodization in ammonium fluoride-water-glycerol solution. ZnO is introduced into the TiO2 nanotube arrays by a convenient electrodeposition technique. ZnO/TiO2 nanocomposites supported on Ti substrate are used as the photo-anode electrode for dye-sensitized solar cells (DSSCs). The morphology, structure and electrochemical properties are investigated using field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV-vis diffusion reflection spectroscopy, X-ray photoelectron spectroscopy and cyclic voltammetry measurements. It is found that ZnO have been embedded in the TiO2 nanotube arrays, and changed some photoelectric properties. The conversion efficiency of the dye-sensitized solar cells is more than doubled, compared with that of bare TiO2 nanotube arrays with deposited 60 min. This improvement comes from the synergetic effect between ZnO and TiO2, which increases dye absorption, electron transport and electron lifetime.

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

    PubMed Central

    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. PMID:24056587

  1. 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. PMID:26789421

  2. 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.

  3. 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. PMID:24304127

  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. Helical TiO2 Nanotube Arrays Modified by Cu-Cu2O with Ultrahigh Sensitivity for the Nonenzymatic Electro-oxidation of Glucose.

    PubMed

    Yang, Qian; Long, Mei; Tan, Lin; Zhang, Yi; Ouyang, Jin; Liu, Ping; Tang, Aidong

    2015-06-17

    A novel Cu-Cu2O/TiO2/Ti electrode for the nonenzymatic electro-oxidation of glucose has been fabricated by secondary anodic oxidation combined with the electrodeposition method. It represents a new type of copper oxide-TiO2 complex nanostructure that demonstrates a new application. At the potential range from -1.0 to -1.6 V, Cu2+ was electrochemically reduced to Cu2O, accompanied by the simultaneous formation of Cu covering the top surface of the TiO2 nanotubes. The highest response current was obtained at the optimized fabrication conditions with a deposition charge of 1.5 C, a pH of 12, 4 mM CuSO4, and a deposition potential of -1.4 V. The results indicate that Cu2O helps to keep a broad linear range, and the incorporation of Cu nanoparticles improves the response current and sensitivity. The linearity between the response current and the glucose concentration was obtained in the range from 0.1 to 2.5 mM with a sensitivity of 4895 μA cm(-2) mM(-1). Such high sensitivity was attributed to the synergistic effect of the small Cu-Cu2O grain size and the large surface area of the helical TiO2 nanotube arrays as well as the fast electron transfer. Electrochemical impedance spectroscopy has been successfully applied to explain the differences among different electrode interfaces and the change rule of nonenzymatic electro-oxidation properties. PMID:25970570

  6. 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.

  7. 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

  8. 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.

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

    PubMed

    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

    2016-03-01

    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. PMID:26878901

  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. Effect of metal-ion doping on the characteristics and photocatalytic activity of TiO2 nanotubes for the removal of toluene from water.

    PubMed

    Yuan, Rongfang; Zhou, Beihai; Hua, Duo; Shi, Chunhong; Ma, Li

    2014-01-01

    Toluene is an extensively used reagent that could cause water pollution and endanger human health. In this work, an O3/UV/ion-doped TiO2 nanotubes process was investigated to obtain the optimum TiO2 nanotubes for effective toluene decomposition. Photocatalytic activity is found to be influenced by the doped-ion type by affecting the ionic radius, valence state, and configuration of the dopant. The calcination temperature and doping concentration, which change the weight fractions of the anatase phase (fA), the Brunauer-Emmett-Teller surface area (SBET), and the energy band gap (Eg) of the catalyst, also affect the photocatalytic activity. When TiO2 is doped with ions, SBET decreases and Eg becomes narrower. The photocatalytic activities of TiO2 for toluene removal increase after doping with Ag(+), Al(3+), Cu(2+), Fe(3+), Mn(2+), Ni(2+), V(5+), and Zn(2+). Moreover, the 1.0% Fe(3+)-doped TiO2 nanotubes calcined at 550 °C have the highest catalytic activity, with a toluene removal efficiency of 70.7%.

  12. Preparation of High-Orderly TIO2 Nanotubes in Different Conditions and Electrolyte Solutions

    NASA Astrophysics Data System (ADS)

    Zhang, Yunhuai; Hu, Fu; Xiao, Peng; Fan, Xiaoyan

    High-orderly nanotubes of titania were fabricated by anodic oxidation of pure titanium substrate in different electrolytes containing fluoride. Different morphological nanotubes of titania were obtained through controlling the different pH value of inorganic electrolytes, and it was found that nanotubes of titanium oxide would not formed when pH value was above 6. The morphological and structural properties of nanotublar products were characterized by SEM. The synthesized nanotubes of titania in organic electrolytic solutions containing fluoride was of 60 μm in length. The experiments demonstrated the length and orderliness of nanotubes of titanium oxide in organic solutions were much better than those in inorganic solutions.

  13. 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.

  14. 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.

  15. Bifunctional 4MBA mediated recyclable SERS-based immunoassay induced by photocatalytic activity of TiO2 nanotube arrays.

    PubMed

    Wang, Xiaolong; Zhou, Lu; Lai, Wei; Jiang, Tao; Zhou, Jun

    2016-09-14

    We first report here a novel recyclable surface-enhanced Raman scattering (SERS)-based immunoassay via the photocatalytic ability of anatase titania nanotube (TiO2-NT) arrays. In this immunoassay, an immune probe was realized by immobilizing anti-CA19-9 onto Ag@SiO2@Ag three core-shell nanoparticles (TCSNPs), which showed a much higher SERS activity than bare Ag NPs with an enhancement ratio of 1.75. Then, the vertically oriented TiO2-NT immune substrate was synthesized by ultra-fast anodic oxidation of flexible titanium foils and functionalised with 4-mercaptobenzoic acid (4MBA) molecules to link them with anti-CA19-9. The immunoassay using the above immune probe and the substrate exhibited a wide linear range from 1000 to 0.5 U mL(-1) and a low detection limit of 0.5 U mL(-1) for CA19-9 due to the excellent SERS performance of Ag@SiO2@Ag TCSNPs. More importantly, the linkage between TiO2-NTs and 4MBA was destroyed by catalyzing 4MBA into 4-sulfobenzoate upon UV irradiation in O2-saturated water. The target antigen and the immune probe were simultaneously removed leading to a recyclable immunoassay and a detection limit of 5 U mL(-1) was achieved after six cycles. The simplicity and versatility of this strategy may bridge the technology gap between academia and practical detection, which makes it promising for clinical SERS-based immunoassay. PMID:27523026

  16. 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.

  17. 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.

  18. 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.

  19. 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. PMID:25818138

  20. 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.

  1. Enhanced photoelectrochemical performance of quantum dot-sensitized TiO2 nanotube arrays with Al2O3 overcoating by atomic layer deposition.

    PubMed

    Zeng, Min; Peng, Xiange; Liao, Jianjun; Wang, Guizhen; Li, Yanfang; Li, Jianbao; Qin, Yong; Wilson, Joshua; Song, Aimin; Lin, Shiwei

    2016-06-29

    While TiO2 nanotube arrays cosensitized with CdS and PbS quantum dots can achieve water splitting under visible light excitation, the use of quantum dots is limited by the relatively slow interfacial hole transfer rate and low internal quantum efficiencies in the visible region. Al2O3 overcoating by atomic layer deposition (ALD) can drastically enhance the photoelectrochemical performance of the quantum dot-sensitized TiO2 nanotube arrays. 30 ALD cycles of the Al2O3 overlayer can achieve a good balance between surface coverage and charge transfer resistance. The resulting maximum photocurrent density of 5.19 mA cm(-2) under simulated solar illumination shows a 52 times improvement over the pure TiO2 nanotube arrays, and more significantly, a 60% enhancement over bare quantum dot-sensitized TiO2 nanotube arrays. The incident photon-to-current conversion efficiency can reach the record value of 83% at 350 nm and remain above 30% up to 450 nm. A systematic examination of the role of the ALD Al2O3 overlayer indicates that surface recombination passivation, catalytic improvement in interfacial charge transfer kinetics, and chemical stabilization might synergistically enhance the photoelectrochemical performance in the visible region. These results provide a physical insight into the facile surface treatment, which could be applied to develop and optimize high-performance photoelectrodes for artificial photosynthesis. PMID:27138558

  2. Lithium ion intercalation of 3-D vertical hierarchical TiO2 nanotubes on a titanium mesh for efficient photoelectrochemical water splitting.

    PubMed

    Xin, Yanmei; Cheng, Yuxiao; Zhou, Yuyan; Li, Zhenzhen; Wu, Hongjun; Zhang, Zhonghai

    2016-03-25

    In this communication, we report for the first time the demonstration of a lithium ion intercalation strategy to significantly enhance the photoelectrochemical water splitting performance on 3-dimensional vertical hierarchical top-porous-bottom-tubular TiO2 nanotubes on a fabricable titanium mesh. PMID:26935068

  3. Surface nano-texturing of silicon by picosecond laser irradiation through TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Babu, K. E. Sarath Raghavendra; Duraiselvam, Muthukannan

    2015-10-01

    This article presents, nano-texturing of crystalline silicon by irradiating picosecond laser with variable spatial intensity, caused by optically non-linear TiO2 nanotube arrays (TNTA). Along with micro-scale surface structure, highly ordered laser-induced periodic surface structures (LIPSS) was observed at nano-scale. The periodicity (Λ) of the LIPSS generated was near to the laser wavelength (532 nm). Surface morphology at micro-level was characterized by optical microscopy (OM) and white light interferometer (WLI) and at the nano-scale by scanning electron microscope (SEM) and atomic force microscope (AFM). The results highlight the potential use of TNTA as a single step process to produce micro/nanostructures without any gas/liquid medium under ambient condition.

  4. High-temperature annealing of TiO2 nanotube membranes for efficient dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Mohammadpour, Fatemeh; Altomare, Marco; So, Seulgi; Lee, Kiyoung; Mokhtar, Mohamed; Alshehri, Abdelmohsen; Al-Thabaiti, Shaeel A.; Schmuki, Patrik

    2016-01-01

    We fabricate photo-anodes by transferring anodic TiO2 nanotube membranes in tube-top-down configuration on FTO glass, and use them for constructing frontside illuminated dye-sensitized solar cells. Prior to solar cell construction, the tube-based photo-anodes are crystallized at different temperatures (400-800 °C), and the effects of tube electron transport properties on the photovoltaic performance of the solar cells are investigated. We show that improved solar cell efficiencies (up to ca. 8.0%) can be reached by high-temperature treatment of the tube membranes. Consistent with electron transport time measurements, remarkably enhanced electron mobility is enabled when tube membranes are crystallized at 600 °C.

  5. 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.

  6. Towards efficient visible-light active photocatalysts: CdS/Au sensitized TiO2 nanotube arrays.

    PubMed

    Nguyen, VanManh; Cai, Qingyun; Grimes, Craig A

    2016-12-01

    A visible-light active photocatalyst, CdS/Au/TiO2 nanotube array (NTA) photoelectrode, was prepared by electrodeposition of Au nanoparticles onto TiO2 NTA with subsequent deposition of visible-light absorbable 2.4eV band-gap CdS quantum dots using successive ion layer adsorption and reaction (SILAR). The Au nanoparticles here act as electron sinks facilitating charge carrier separation. Under AM1.5G illumination a photoconversion efficiency of 4.06% was achieved for the CdS/Au/TiO2 NTA photoelectrode, suggesting the promise of the material architecture for achieving high-performance cost-effective materials. PMID:27565960

  7. Designing tissue phantoms for ultrasonography and elastography with TiO2 incorporated polyacrylamide hydrogels

    NASA Astrophysics Data System (ADS)

    Kumar, Kishore; Mohanty, Maneesha Esther; Jayashankar, V.; Suresh, S.; Mishra, Ashok K.

    2012-07-01

    Research on ultrasonography and elastography instrumentation is crucially dependent on the quality of tissue-mimicking phantoms on which the instrumental parameters are tested. The phantoms should ideally possess values of various acoustic parameters corresponding to normal and abnormal tissues of different types and these properties should not change significantly with time. Designing such phantoms requires a molecular level understanding of the material to be used. In this context, polyacrylamide gels made from corresponding monomer, initiator and cross-linker were developed. An understanding of the network structure of these hydrogels at the molecular level was made possible using fluorescence spectroscopy with anilinonaphthylsulfonate as an extrinsic fluorescent probe. TiO2 was used to adjust the acoustic transparency so as to bring the ultrasound reflection parameters close to those of human tissues. It was found that the network structure of poly-acrylamide (PAM) hydrogels as well as their acoustic and viscoelastic properties could be conveniently varied by altering the composition of the components. This understanding at the molecular as well as the bulk level was then used to develop tissue phantoms appropriate for imaging in ultrasound-B and elastography modes.

  8. 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.

  9. Hydrothermal growth of TiO2 nanorod arrays and in situ conversion to nanotube arrays for highly efficient quantum dot-sensitized solar cells.

    PubMed

    Huang, Hui; Pan, Lei; Lim, Chiew Keat; Gong, Hua; Guo, Jun; Tse, Man Siu; Tan, Ooi Kiang

    2013-09-23

    TiO2 nanorod (NR) and nanotube (NT) arrays grown on transparent conductive substrates are attractive electrode for solar cells. In this paper, TiO2 NR arrays are hydrothermally grown on FTO substrate, and are in situ converted into NT arrays by hydrothermally etching. The TiO2 NR arrays are reported as single crystalline, but the TiO2 NR arrays are demonstrated to be polycrystalline with a bundle of 2-5 nm single crystalline nanocolumns grown along [001] throughout the whole NR from bottom to top. TiO2 NRs can be converted to NTs by hydrothermal selective etching of the (001) core and remaining the inert sidewall of (110) face. A growth mechanism of the NR and NT arrays is proposed. Quantum dot-sensitized solar cells (QDSCs) are fabricated by coating CdSe QDs on to the TiO2 arrays. After conversion from NRs to NTs, more QDs can be filled in the NTs and the energy conversion efficiency of the QDSCs almost double.

  10. Preparation of TiO2 nanowires/nanotubes using polycarbonate membranes and their uses in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Roh, Dong Kyu; Patel, Rajkumar; Ahn, Sung Hoon; Kim, Dong Jun; Kim, Jong Hak

    2011-10-01

    Track-etched polycarbonate (PC) membranes were used as a soft template to synthesize mesoporous TiO2 for use in dye-sensitized solar cells (DSSCs). The Ti precursor infiltrated into the cylindrical confined spaces of PC membranes. Upon calcination at 500 °C, TiO2 nanowires (15TNW) were obtained from PC with a 15 nm pore diameter, whereas TiO2 nanotubes (50TNT and 100TNT) were generated from PC with 50 and 100 nm diameter pores, respectively. TNW and TNT were used as photoelectrodes in DSSCs employing a polymer electrolyte. The ranking of the cell efficiencies of the 200 nm thick TiO2 films was 50TNT (1.1%) > 15TNW (0.8%) ≅ 100TNT (0.7%), which was mostly attributed to different amounts of dye adsorption due to different surface areas. These TNW and TNT films were further coated with the graft copolymer-directed mesoporous TiO2 and were used as interfacial layers between the FTO glass and the 4 μm thick nanocrystalline TiO2 film. As a result, the order of energy conversion efficiency was 15TNW (5.0%) ≅ 50TNT (4.8%) > 100TNT (4.1%). The improved performance of 15TNW was due to a higher transmittance through the electrode and a longer electron lifetime for recombination. The DSSC performance was systematically investigated in terms of interfacial resistance and charge recombination using electrochemical impedance spectroscopy.

  11. 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

  12. TiO2 nanotube stimulate chondrogenic differentiation of limb mesenchymal cells by modulating focal activity

    PubMed Central

    Kim, Dongkyun; Choi, Bohm; Song, Jinsoo; Kim, Sunhyo; Oh, Seunghan; Jin, Eun-Heui; Kang, Shin-Sung

    2011-01-01

    Vertically aligned, laterally spaced nanoscale titanium nanotubes were grown on a titanium surface by anodization, and the growth of chondroprogenitors on the resulting surfaces was investigated. Surfaces bearing nanotubes of 70 to 100 nm in diameter were found to trigger the morphological transition to a cortical actin pattern and rounded cell shape (both indicative of chondrocytic differentiation), as well as the up-regulation of type II collagen and integrin β4 protein expression through the down-regulation of Erk activity. Inhibition of Erk signaling reduced stress fiber formation and induced the transition to the cortical actin pattern in cells cultured on 30-nm-diameter nanotubes, which maintained their fibroblastoid morphologies in the absence of Erk inhibition. Collectively, these results indicate that a titanium-based nanotube surface can support chondrocytic functions among chondroprogenitors, and may therefore be useful for future cartilaginous applications. PMID:21677506

  13. 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.

  14. Electrochemically hydrogenated TiO2 nanotubes with improved photoelectrochemical water splitting performance

    PubMed Central

    2013-01-01

    One-dimensional anodic titanium oxide (ATO) nanotube arrays hold great potential as photoanode for photoelectrochemical (PEC) water splitting. In this work, we report a facile and eco-friendly electrochemical hydrogenation method to modify the electronic and PEC properties of ATO nanotube films. The hydrogenated ATO (ATO-H) electrodes present a significantly improved photocurrent of 0.65 mA/cm2 in comparison with that of pristine ATO nanotubes (0.29 mA/cm2) recorded under air mass 1.5 global illumination. The incident photon-to-current efficiency measurement suggests that the enhanced photocurrent of ATO-H nanotubes is mainly ascribed to the improved photoactivity in the UV region. We propose that the electrochemical hydrogenation induced surface oxygen vacancies contribute to the substantially enhanced electrical conductivity and photoactivity. PMID:24047205

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

    DOE PAGESBeta

    Liu, Jing; Hosseinpour, Pegah M.; Luo, Si; Heiman, Don; Menon, Latika; Arena, Dario A.; Lewis, Laura H.

    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. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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. PMID:27383450

  2. Towards TiO2 nanotubes modified by WO3 species: influence of ex situ crystallization of precursor on the photocatalytic activities of WO3/TiO2 composites

    NASA Astrophysics Data System (ADS)

    Sun, Hui; Dong, Bohua; Su, Ge; Gao, Rongjie; Liu, Wei; Song, Liang; Cao, Lixin

    2015-09-01

    TiO2 nanotubes (TNT) crystallized at different temperatures were loaded with WO3 hydrate through the reaction between (NH4)6W7O24·6H2O and an aqueous solution of HCl. The photocatalytic activities of nanocomposites firstly increase and then decrease as a function of the crystallized temperature of the TNT precursor. The structural, morphologic and optical properties of WO3/TiO2 nanocomposites were also investigated in this study. The samples, initially anatase titania (573 K-773 K), presented phase transition to rutile titania at 873 K. With the crystallized temperature increasing, an evolution of samples morphology changing from nanotube-like structure to nanorod-like structure was observed. Meanwhile, the absorption edge of samples exhibited a red shift, and correspondingly their band gap decreased. Consistent with x-ray diffraction diffractograms, the existence of rutile titania as an impurity in the precursor TNT, crystallized at higher than 873 K, depressed photocatalytic activity evidently. As a result, the degradation rate of methyl orange (MO) increased with the samples crystallinity firstly, and then reduced due to the appearance of rutile titania. In our experimental conditions, the optimal photocatalytic activity was achieved for the sample crystalized at 773 K. Its degradation rate could reach 98.76% after 90 min UV light irradiation.

  3. CdTe and graphene co-sensitized TiO2 nanotube array photoanodes for protection of 304SS under visible light

    NASA Astrophysics Data System (ADS)

    Li, Hong; Wang, Xiutong; Zhang, Liang; Hou, Baorong

    2015-04-01

    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.

  4. 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. PMID:25804558

  5. 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

  6. 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.

  7. 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. PMID:26911568

  8. Preparation and UV-Vis photodegradation of gaseous benzene by TiO2 nanotube arrays supporting V2O5 nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhao, Chunxia; Song, Yanbao; Yang, Yunxia; Chen, Wen; Li, Xiaoyu; Wang, Zongsheng

    2015-07-01

    TiO2-based catalysts effective in visible radiation for eliminating organic pollutants have attracted intense research activity as a future generation photocatalytic material. However, recombination of electron-hole pairs through trapping/de-trapping as well as the disadvantages of recycling and separation/filtration of powders lead to the limitation of powder TiO2 materials. TiO2 nanotube array films supporting vanadium pentoxide nanoparticles (VTNTs) were synthesized by electrophoresis deposition method with the prepared TiO2 nanotube arrays as the cathode and V2O5 sol as the electrolyte. The results indicate that the formation of Ti-O-V bonds and intimate interaction between host-guest interfaces help to enhance the hybrids’ photodegradation activity of gaseous benzene. Importantly, hybrid film catalysts prepared with 0.05 mol/L V2O5 sol for 10 min electrophoresis deposition perform a 98% conversion rate of benzene and 1028.8 mg/m3CO2 production in 80 min under UV-Vis irradiation.

  9. 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.

  10. TiO2 nanotubes as drug nanoreservoirs for the regulation of mobility and differentiation of mesenchymal stem cells.

    PubMed

    Hu, Yan; Cai, Kaiyong; Luo, Zhong; Xu, Dawei; Xie, Daichao; Huang, Yuran; Yang, Weihu; Liu, Peng

    2012-01-01

    The extracellular microenvironment plays a key role in the regulation of cellular behavior. To mimic the natural extracellular microenvironment, TiO(2) nanotube (TNT) arrays as drug nanoreservoirs for loading of bone morphogenetic protein 2 (BMP2) were constructed on titanium substrates and then covered with multilayered coatings of gelatin/chitosan (Gel/Chi) for controlled drug release. The multilayered coatings were constructed via a spin-assisted layer-by-layer assembly technique. The successful fabrication of this system was monitored by field emission scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy and contact angle measurements. Multilayered coating with Gel/Chi retained the drug bioactivity and release properties, which were revealed by superoxide dismutase activity measurement. In addition, cytoskeleton observation and wound healing assay confirmed that BMP2-loaded and multilayer-coated TNT arrays were able to stimulate motogenic responses of mesenchymal stem cells (MSCs). More importantly, the system demonstrated that it was capable of promoting the osteoblastic differentiation of MSCs. This study may have potential impact on the development of bone implants for enhanced bone osseointegration.

  11. Bioinspired patterning with extreme wettability contrast on TiO2 nanotube array surface: a versatile platform for biomedical applications.

    PubMed

    Lai, Yuekun; Lin, Longxiang; Pan, Fei; Huang, Jianying; Song, Ran; Huang, Yongxia; Lin, Changjian; Fuchs, Harald; Chi, Lifeng

    2013-09-01

    Binary wettability patterned surfaces with extremely high wetting contrasts can be found in nature on living creatures. They offer a versatile platform for microfluidic management. In this work, a facile approach to fabricating erasable and rewritable surface patterns with extreme wettability contrasts (superhydrophilic/superhydrophobic) on a TiO2 nanotube array (TNA) surface through self-assembly and photocatalytic lithography is reported. The multifunctional micropatterned superhydrophobic TNA surface can act as a 2D scaffold for site-selective cell immobilization and reversible protein absorption. Most importantly, such a high-contrast wettability template can be used to construct various well-defined 3D functional patterns, such as calcium phosphate, silver nanoparticles, drugs, and biomolecules in a highly selective manner. The 3D functional patterns would be a versatile platform in a wide range of applications, especially for biomedical devices (e.g., high-throughput molecular sensing, targeted antibacterials, and drug delivery). In a proof-of-concept study, the surface-enhanced Raman scattering and antibacterial performance of the fabricated 3D AgNP@TNA pattern, and the targeted drug delivery for site-specific and high-sensitivity cancer cell assays was investigated.

  12. 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

  13. 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

    2011-09-01

    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.

  14. 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.

  15. Preconcentration of nickel and cadmium by TiO2 nanotubes as solid-phase extraction adsorbents coupled with flame atomic absorption spectrometry.

    PubMed

    Zhou, Qing-Xiang; Zhao, Xin-Ning; Xiao, Jun-Ping

    2009-03-15

    TiO(2) nanotubes, a new nanomaterial, are often used in the photocatalysis. Due to its relatively large specific surface areas it should have a higher enrichment capacity. However, very few applications in the enrichment of pollutants were found. This paper described a new procedure to investigate the trapping power of TiO(2) nanotubes with cadmium and nickel in water samples as the model analytes and flame atomic absorption spectrometry for the analysis. The possible parameters influencing the enrichment were optimized. Under the optimal SPE conditions, the method detection limits and precisions (R.S.D., n=6) were 0.25 ngmL(-1) and 2.2% for cadmium, 1 ngmL(-1) and 2.6% for nickel, respectively. The established method has been successfully applied to analyze four realworld water samples, and satisfactory results were obtained. The spiked recoveries were in the range of 90.2-99.2% for them. All these indicated that TiO(2) nanotubes had great potential in environmental field.

  16. Front-side illuminated CdS/CdSe quantum dots co-sensitized solar cells based on TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Guan, Xiao-Fang; Huang, Shu-Qing; Zhang, Quan-Xin; Shen, Xi; Sun, Hui-Cheng; Li, Dong-Mei; Luo, Yan-Hong; Yu, Ri-Cheng; Meng, Qing-Bo

    2011-11-01

    We fabricated a front-side illuminated CdS/CdSe quantum dots co-sensitized solar cell based on TiO2 nanotube arrays. The freestanding TiO2 nanotube arrays were first detached from anodic oxidized Ti foils and then transferred to the fluorine-doped tin oxide to form photoanodes. An opaque Cu2S with high electrochemical activity was used as the counter electrode. A photovoltaic conversion efficiency as high as 3.01% under one sun illumination has been achieved after optimizing the deposition time of CdSe quantum dots and the length of the TiO2 nanotube arrays. It is observed that the power conversion efficiency of quantum dots sensitized solar cells from the front-side illumination mode (3.01%) is much higher than that of the back-side illumination mode (1.32%) owing to the poor catalytic activity of Pt to polysulfide electrolytes and light absorption by the electrolytes for the latter.

  17. Effect of fluoride and water content on the growth of TiO2 nanotubes synthesized via ethylene glycol with voltage changes during anodizing process

    NASA Astrophysics Data System (ADS)

    Quiroz, Heiddy P.; Quintero, Francisco; Arias, Pedro J.; Dussan, A.; Zea, Hugo R.

    2015-07-01

    In this work, titanium foils were anodized in ethylene glycol solutions containing different amounts of water and fluoride to determine their effects on the top morphology and crystalline structure of the formed titania nanostructures. Anodizing was performed for 2 h by using titanium foils as both anode and cathode applying a squared-pulse voltage profile composed of one step at 80 V for 3 min followed by another at 20 V for 5 min; constant voltage conditions were also used to study the nanostructure formation on the surface. We found the formation of nanostructured titania on the surface of the anodized foil when small amounts of water and fluoride are present in the anodizing solution. The top of these nanostructures is irregular when no water is added, but is expected to change with different amounts of water and fluoride in the ranges of 1 - 9% and 0.05 - 0.5%, respectively. Synthesis parameters also change nanotube morphology. The morphology and structure properties of the samples were studied by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). Formation of TiO2 nanotubes by anodization method are strongly correlated to conditions like fluoride concentration and applied voltages. Tube length varying between 2 and 7 μm, exhibiting different diameters and wall thicknesses were obtained. When an alternate voltage was applied, the wall of the nanotubes presented evenly spaced rings while nanotubes with smooth wall form were observed when constant voltage was applied. Reflection peaks corresponding to Brookite, Anatase, and Rutile of TiO2 phases were observed from XRD measurements. A correlation between the effects of synthesis parameters on nanotube formation and morphological properties is presented. TiO2 nanotubes prepared by electrochemical anodization have excellent performance in various applications such as photocatalysts, solar cells, gas sensors, and biomedical applications.

  18. Improved charge transfer and photoelectrochemical performance of CuI/Sb2S3/TiO2 heterostructure nanotube arrays.

    PubMed

    Yang, Feng; Xi, Jinfang; Gan, Li-Yong; Wang, Yushu; Lu, Shuangwei; Ma, Wenli; Cai, Fanggong; Zhang, Yong; Cheng, Cuihua; Zhao, Yong

    2016-02-15

    Charge transfer is important for the performance of a photoelectrochemical cell. Understanding photogenerated charge accumulation and separation is mandatory for the design and optimisation of photoelectrochemical cells. Unique stacked and embedded heterostructure of Sb2S3/TiO2 nanotube arrays (NTAs) was fabricated through anodic oxidation with the hydrothermal method. Surface photovoltage spectroscopy, phase spectra and photoluminescence measurements were performed to explore the mechanism by which the inorganic hole transport material CuI affects the charge transfer and photoelectrochemical properties of Sb2S3/TiO2 heterostructure NTAs. The interfacial separation and transport of photoinduced charge carriers were also examined by applying current-voltage characteristics (J-V), incident-photon-to-current conversion efficiency (IPCE) and Mott-Schottky techniques. Results show that CuI acts not only as a hole-conducting and electron-blocking material but also as a light-absorbing material in the ultraviolet range. Efficient charge transfer processes exist in CuI/Sb2S3/TiO2 heterostructure NTAs. The photoelectrochemical performance of CuI/Sb2S3/TiO2 heterostructure NTAs is dramatically improved. Under AM 1.5G illumination at 100mW/cm(2), the short-circuit current density and open-circuit voltage are 3.51mA/cm(2) and 0.87V, respectively. The photoelectric conversion efficiency of CuI/Sb2S3/TiO2 heterostructure NTAs (0.95%) is 36% higher than that of Sb2S3/TiO2 heterostructure NTAs (0.66%). PMID:26598949

  19. 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

  20. 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.

  1. 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. PMID:25842121

  2. The effect of carbon nanotubes and titanium dioxide incorporated in PDMS on biofilm community composition and subsequent mussel plantigrade settlement.

    PubMed

    Yang, Jin-Long; Li, Yi-Feng; Guo, Xing-Pan; Liang, Xiao; Xu, Yue-Feng; Ding, De-Wen; Bao, Wei-Yang; Dobretsov, Sergey

    2016-08-01

    This study investigated the effect of carbon nanotubes (CNTs) and titanium dioxide (TiO2) incorporated in PDMS on biofilm formation and plantigrade settlement of Mytilus coruscus. TiO2 increased bacterial density, and CNTs also increased bacterial density but reduced diatom density in biofilms after 28 days. Further analysis was conducted between bacterial communities on glass, PDMS, CNTs (0.5 wt%) and TiO2 (7.5 wt%). ANOSIM analysis revealed significant differences (R > 0.9) between seven, 14, 21 and 28 day-old bacterial communities. MiSeq sequencing showed that CNTs and TiO2 impacted the composition of 28 day-old bacterial communities by increasing the abundance of Proteobacteria and decreasing the abundance of Bacteroidetes. The maximum decreased settlement rate in 28 day-old biofilms on CNTs and TiO2 was > 50% in comparison to those on glass and PDMS. Thus, CNTs and TiO2 incorporated in PDMS altered the biomass and community composition of biofilms, and subsequently decreased mussel settlement.

  3. The effect of carbon nanotubes and titanium dioxide incorporated in PDMS on biofilm community composition and subsequent mussel plantigrade settlement.

    PubMed

    Yang, Jin-Long; Li, Yi-Feng; Guo, Xing-Pan; Liang, Xiao; Xu, Yue-Feng; Ding, De-Wen; Bao, Wei-Yang; Dobretsov, Sergey

    2016-08-01

    This study investigated the effect of carbon nanotubes (CNTs) and titanium dioxide (TiO2) incorporated in PDMS on biofilm formation and plantigrade settlement of Mytilus coruscus. TiO2 increased bacterial density, and CNTs also increased bacterial density but reduced diatom density in biofilms after 28 days. Further analysis was conducted between bacterial communities on glass, PDMS, CNTs (0.5 wt%) and TiO2 (7.5 wt%). ANOSIM analysis revealed significant differences (R > 0.9) between seven, 14, 21 and 28 day-old bacterial communities. MiSeq sequencing showed that CNTs and TiO2 impacted the composition of 28 day-old bacterial communities by increasing the abundance of Proteobacteria and decreasing the abundance of Bacteroidetes. The maximum decreased settlement rate in 28 day-old biofilms on CNTs and TiO2 was > 50% in comparison to those on glass and PDMS. Thus, CNTs and TiO2 incorporated in PDMS altered the biomass and community composition of biofilms, and subsequently decreased mussel settlement. PMID:27348759

  4. Designing nanostructured one-dimensional TiO2 nanotube and TiO2 nanoparticle multilayer composite film as photoanode in dye-sensitized solar cells to increase the charge collection efficiency

    NASA Astrophysics Data System (ADS)

    Akilavasan, Jeganathan; Al-Jassim, Maufick; Bandara, Jayasundera

    2015-01-01

    A photoanode consisting of hydrothermally synthesized TiO2 nanotubes (TNT) and TiO2 nanoparticles (TNP) was designed for efficient charge collection in dye-sensitized solar cells. TNT and TNP films were fabricated on a conductive glass substrate by using electrophoretic deposition and doctor-blade methods, respectively. The TNP, TNT, and TNT/TNP bi-layer electrodes exhibit solar cell efficiencies of 5.3, 7.4, and 9.2%, respectively. Solar cell performance results indicate a higher short-circuit current density (Jsc) for the TNT/TNP bi-layer electrode when compared to a TNT or TNP electrode alone. The open-circuit voltages (Voc) of TNT/TNP and TNT electrodes are comparable while the Voc of TNP electrode is inferior to that of the TNT/TNP electrode. Fill factors of TNT/TNP, TNT, and TNP electrodes also exhibit similar behaviors. The enhanced efficiency of the TNT/TNP bi-layer electrode is found to be mainly due to the enhancement of charge collection efficiency, which is confirmed by the charge transport parameters measured by electrochemical impedance spectroscopy (EIS). EIS analyses also revealed that the TNT/TNP incurs smaller charge transport resistances and longer electron life times when compared to those of TNT or TNP electrodes alone. It was demonstrated that the TNT/TNP bi-layer electrode can possess the advantages of both rapid electron transport rate and a high light scattering effect.

  5. 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.

  6. 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.

  7. 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. PMID:21443251

  8. 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.

  9. 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

  10. A thermal study on the structural changes of bimetallic ZrO2-modified TiO2 nanotubes synthesized using supercritical CO2.

    PubMed

    Lucky, R A; Charpentier, P A

    2009-05-13

    In this study the thermal behavior of bimetallic ZrO(2)-TiO(2) (10/90 mol/mol) nanotubes are discussed which were synthesized via a sol-gel process in supercritical carbon dioxide (scCO(2)). The effects of calcination temperature on the morphology, phase structure, mean crystallite size, specific surface area and pore volume of the nanotubes were investigated by using a variety of physiochemical techniques. We report that SEM and TEM images showed that the nanotubular structure was preserved at up to 800 degrees C calcination temperature. When exposed to higher temperatures (900-1000 degrees C) the ZrO(2)-TiO(2) tubes deformed and the crystallites fused together, forming larger crystallites, and a bimetallic ZrTiO(4) species was detected. These results were further examined using TGA, FTIR, XRD and HRTEM analysis. The BET textural properties demonstrated that the presence of a small amount of Zr in the TiO(2) matrix inhibited the grain growth, stabilized the anatase phase and increased the thermal stability. PMID:19420640

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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. PMID:23062512

  17. High-Performance Stable Field Emission with Ultralow Turn on Voltage from rGO Conformal Coated TiO2 Nanotubes 3D Arrays.

    PubMed

    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/cm(2)), 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

  18. High-Performance Stable Field Emission with Ultralow Turn on Voltage from rGO Conformal Coated TiO2 Nanotubes 3D Arrays

    NASA Astrophysics Data System (ADS)

    Agrawal, Yogyata; Kedawat, Garima; Kumar, Pawan; Dwivedi, Jaya; Singh, V. N.; Gupta, R. K.; Gupta, Bipin Kumar

    2015-07-01

    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.

  19. A cylindrical core-shell-like TiO2 nanotube array anode for flexible fiber-type dye-sensitized solar cells

    PubMed Central

    2011-01-01

    A versatile anodization method was reported to anodize Ti wires into cylindrical core-shell-like and thermally crystallized TiO2 nanotube (TNT) arrays that can be directly used as the photoanodes for semi- and all-solid fiber-type dye-sensitized solar cells (F-DSSC). Both F-DSSCs showed higher power conversion efficiencies than or competitive to those of previously reported counterparts fabricated by depositing TiO2 particles onto flexible substrates. The substantial enhancement is presumably attributed to the reduction of grain boundaries and defects in the prepared TNT anodes, which may suppress the recombination of the generated electrons and holes, and accordingly lead to more efficient carrier-transfer channels. PMID:21711629

  20. 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.

  1. 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

  2. Hybrid micro/nano-topography of a TiO2 nanotube-coated commercial zirconia femoral knee implant promotes bone cell adhesion in vitro

    PubMed Central

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

    2014-01-01

    Various approaches have been studied to engineer the implant surface to enhance bone in-growth properties, particularly using micro- and nano- topography. In this study, the behavior of osteoblast (bone) cells was analyzed in response to a titanium oxide (TiO2) nanotube-coated commercial zirconia femoral knee implant consisting of a combined surface structure of a micro-roughened surface with the nanotube coating. The osteoblast cells demonstrated high degrees of adhesion and integration into the surface of the nanotube-coated implant material, indicating preferential cell behavior on this surface when compared to the bare implant. The results of this brief study provide sufficient evidence to encourage future studies. The development of such hierarchical micro and nano topographical features, as demonstrated in this work, can provide for insightful designs for advanced bone-inducing material coatings on ceramic orthopedic implant surfaces. PMID:23623092

  3. XPS and DFT study of Sn incorporation into ZnO and TiO2host matrices by pulsed ion implantation

    NASA Astrophysics Data System (ADS)

    Zatsepin, D. A.; Boukhvalov, D. W.; Kurmaev, E. Z.; Zhidkov, I. S.; Kim, S. S.; Cui, L.; Gavrilov, N. V.; Cholakh, S. O.

    2015-08-01

    Bulk and thin films ZnO and TiO2 samples were doped with Sn by pulsed ion implantation and studied by means of X-ray photoelectron core-level and valence band spectroscopy as well as density functional theory calculations for comprehensive study of the incorporation of Sn. XPS spectral analysis showed that isovalent Sn cation substitution occurs in both zinc oxide (Sn2+ -> Zn2+) and titanium dioxide (Sn4+ -> Ti4+) for bulk and film morphologies. For TiO2 films, the implantation also led to occupation of interstitials by doped ions, which induced the clustering of substituted and embedded Sn atoms; this did not occur in ZnO:Sn film samples. Density functional theory (DFT) formation energies were calculated of various incorporation processes, explaining the prevalence of substitutional defects in both matrices. Possible mechanisms and reasons for the observed trends in Sn incorporation into the ZnO and TiO2 matrices are discussed.

  4. Silicon on conductive self-organized TiO2 nanotubes - A high capacity anode material for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Brumbarov, Jassen; Kunze-Liebhäuser, Julia

    2014-07-01

    The study of high energy density electrode materials is central to the development of Li+-ion batteries. Si is among the most promising anode materials for next generation Li+-ion batteries. Model composite electrodes of self-organized, conductive titania (TiO2-x-C) nanotubes coated with silicon (Si) via plasma enhanced chemical vapor deposition (PECVD) are produced and studied in terms of their lithiation/delithiation characteristics. The nanotube array provides direct one dimensional electron transport to the current collector, without the need of adding binders or conductive additives. Both components of the composite can be lithiated delivering 120 μAh cm-2 total capacity for a film thickness of 1 μm and a Si loading of ∼10 wt.%. 86% capacity retention upon 88 cycles at a rate of C/5 and 60 μAh cm-2 total capacity at a rate of 10 C are achieved owing to the low lateral expansion and thus good adhesion of the thin Si coating to the TiO2-x-C nanotubes, and due to the formation of a stable solid electrolyte interface (SEI) in ethylene-carbonate (EC), dimethyl-carbonate (DMC), vinylene-carbonate (VC) electrolyte with 1 M LiPF6.

  5. 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.

  6. 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. PMID:26096447

  7. 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.

  8. 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.

  9. Rational design of anatase TiO2 architecture with hierarchical nanotubes and hollow microspheres for high-performance dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Gu, Jiuwang; Khan, Javid; Chai, Zhisheng; Yuan, Yufei; Yu, Xiang; Liu, Pengyi; Wu, Mingmei; Mai, Wenjie

    2016-01-01

    Large surface area, sufficient light-harvesting and superior electron transport property are the major factors for an ideal photoanode of dye-sensitized solar cells (DSSCs), which requires rational design of the nanoarchitectures and smart integration of state-of-the-art technologies. In this work, a 3D anatase TiO2 architecture consisting of vertically aligned 1D hierarchical TiO2 nanotubes (NTs) with ultra-dense branches (HTNTs, bottom layer) and 0D hollow TiO2 microspheres with rough surface (HTS, top layer) is first successfully constructed on transparent conductive fluorine-doped tin oxide glass through a series of facile processes. When used as photoanodes, the DSSCs achieve a very large short-current density of 19.46 mA cm-2 and a high overall power conversion efficiency of 8.38%. The remarkable photovoltaic performance is predominantly ascribed to the enhanced charge transport capacity of the NTs (function as the electron highway), the large surface area of the branches (act as the electron branch lines), the pronounced light harvesting efficiency of the HTS (serve as the light scattering centers), and the engineered intimate interfaces between all of them (minimize the recombination effect). Our work demonstrates a possibility of fabricating superior photoanodes for high-performance DSSCs by rational design of nanoarchitectures and smart integration of multi-functional components.

  10. 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

    2013-01-01

    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.

  11. 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

    2016-10-01

    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.

  12. Photogenerated charges transfer across the interface between NiO and TiO2 nanotube arrays for photocatalytic degradation: A surface photovoltage study.

    PubMed

    Hou, Libo; Li, Shuo; Lin, Yanhong; Wang, Dejun; Xie, Tengfeng

    2016-02-15

    To better understand the behavior of photogenerated charges in the composite photocatalyst interface is beneficial to the designing of effective photocatalyst for photocatalytic reaction. In our work, the separation and transfer process of photogenerated charges in NiO/TiO2 nanotube arrays (NiO/TiO2 NTAs) has been studied by surface photovoltage (SPV) spectroscopy and transient photovoltage (TPV) measurement. Through the experimental results analysis, we find that an interfacial electric field is formed at NiO/TiO2 NTAs interface, which is attributed to the work function difference between NiO and TiO2 NTAs. The photogenerated holes in TiO2 can transfer to the NiO layer along the interface electric field under the ultraviolet irradiation. A large amount of photogenerated holes can be separated effectively and then prolonged the holes lifetime to participate in the photocatalytic oxidation reaction. The above results show that the favorable hole-collecting process of NiO in the surface of TiO2 NTAs is the main factor being responsible for the increase the photocatalytic efficiency.

  13. Synthesis, features and solar-light-driven photocatalytic activity of TiO2 nanotube arrays loaded with SnO2.

    PubMed

    Sim, Lan Ching; Ng, Kai Wern; Ibrahim, Shaliza; Saravanan, Pichiah

    2014-09-01

    In the present study TiO2 nanotube arrays (TNTs) were loaded with a post-transition metal oxide particles namely SnO2 via incipient wet impregnation method by varying its concentration (1.59 wt%, 2.25 wt% and 2.84 wt%). The photocatalytic activity of the prepared photocatalyst was evaluated for the degradation of methylene blue (MB) in presence of natural solar light irradiation. The morphological analyses revealed that the prepared TNTs had average inner diameter of 109 nm, wall thickness of 15 nm and tube length of 7-10 μm, respectively, while the crystalline phase and Raman spectra confirmed the 100% anatase mineral form of TiO2. Further, the presence of SnO2 in TNTs was confirmed by high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The visible light absorption properties of TNTs improved drastically with increasing SnO2 loadings. The coupling effect of SnO2 and TiO2 significantly enhanced degradation efficiency of MB. An 84% degradation of MB was achieved in 6 h of irradiation under clear sky condition. PMID:25924362

  14. (0 0 1) Facet-exposed anatase-phase TiO2 nanotube hybrid reduced graphene oxide composite: Synthesis, characterization and application in photocatalytic degradation

    NASA Astrophysics Data System (ADS)

    Zhou, Xun; Shi, Tiejun; Wu, Jing; Zhou, Haiou

    2013-12-01

    Reduced graphene oxide (RGO) and TiO2 nanotube (TNT) with (0 0 1) facet-exposed anatase phase are covalently bonded together to synthesize TNT hybrid RGO (RGO-TNT) through consecutive process such as hydrothermal reaction, HCl washing, lyophilization and heat treatment with graphene oxide (GO), TiO2 powder and high concentration NaOH solution as the starting materials. The TNT with the diameter between 10 and 20 nm characterized by high resolution transmission electron microscopy (HRTEM) is in anatase phase proven by X-ray diffraction (XRD) and HRTEM. Additionally, the more active (0 0 1) facet is exposed identified by HRTEM. More significantly, TNT is bridged to RGO by Csbnd Ti bond by the measurement of X-ray photoelectron spectroscopy (XPS). The photoluminescence (PL) spectra has testified that RGO in RGO-TNT can transfer and accept photoelectrons from TNT. The photocatalytic activity of RGO-TNT for degrading methylene blue (MB) is enhanced by contrast with pure TNT, and changeable by adjusting the mass ratios of GO to TiO2 powder. Simultaneously, lyophilization is benefit for maintaining the high active surface area of RGO-TNT, which is deeply in relationship with a higher photocatalytic activity. After four running cycles of photocatalytic degradation, RGO-TNT has shown a high stability and perfect reproducibility.

  15. 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

    2012-07-01

    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.

  16. Enhanced photoelectrochemical water splitting performance of TiO2 nanotube arrays coated with an ultrathin nitrogen-doped carbon film by molecular layer deposition.

    PubMed

    Tong, Xili; Yang, Peng; Wang, Yunwei; Qin, Yong; Guo, Xiangyun

    2014-06-21

    Vertically oriented TiO2 nanotube arrays (TNTAs) were conformally coated with an ultrathin nitrogen-doped (N-doped) carbon film via the carbonization of a polyimide film deposited by molecular layer deposition and simultaneously hydrogenated, thereby creating a core/shell nanostructure with a precisely controllable shell thickness. The core/shell nanostructure provides a larger heterojunction interface to substantially reduce the recombination of photogenerated electron-hole pairs, and hydrogenation enhances solar absorption of TNTAs. In addition, the N-doped carbon film coating acts as a high catalytic active surface for oxygen evolution reaction, as well as a protective film to prevent hydrogen-treated TiO2 nanotube oxidation by electrolyte or air. As a result, the N-doped carbon film coated TNTAs displayed remarkably improved photocurrent and photostability. The TNTAs with a N-doped carbon film of ∼ 1 nm produces a current density of 3.6 mA cm(-2) at 0 V vs. Ag/AgCl under the illumination of AM 1.5 G (100 mW cm(-2)), which represents one of the highest values achieved with modified TNTAs. Therefore, we propose that ultrathin N-doped carbon film coating on materials is a viable approach to enhance their PEC water splitting performance.

  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. 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.

  19. 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.

  20. Plasmonic silver quantum dots coupled with hierarchical TiO2 nanotube arrays photoelectrodes for efficient visible-light photoelectrocatalytic hydrogen evolution

    PubMed Central

    Lian, Zichao; Wang, Wenchao; Xiao, Shuning; Li, Xin; Cui, Yingying; Zhang, Dieqing; Li, Guisheng; Li, Hexing

    2015-01-01

    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. PMID:26067850

  1. 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

    2015-01-01

    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. PMID:26067850

  2. TiO2 nanotube array-graphene-CdS quantum dots composite film in Z-scheme with enhanced photoactivity and photostability.

    PubMed

    Xian, Jiangjun; Li, Danzhen; Chen, Jing; Li, Xiaofang; He, Miao; Shao, Yu; Yu, Linhui; Fang, Jialin

    2014-08-13

    The most efficient solar energy utilization is achieved in natural photosynthesis through elaborate cell membrane with many types of molecules ingeniously transferring photogenerated electrons to reactants in a manner similar to the so-called Z-scheme mechanism. However, artificial photosynthetic systems based on semiconductor nanoparticles are inevitably accompanied by undesired non-Z-scheme electron transfer and back reactions, which adversely affect the photoactivity and photostability of the systems. Herein, we report on a novel Z-scheme system with an electrochemically converted graphene (GR) film as the electron mediator interlayer contacted with both TiO2 nanotube (TNT) array and CdS quantum dots (CdS QDs) on two sides. The obtained TiO2 nanotube array-graphene-CdS quantum dots (TNT-GR-CdS) composite film shows higher photoelectric response and photocatalytic activities than other bare TNT, TNT-CdS, TNT-GR, and TNT-CdS-GR. Moreover, compared to TNT-CdS, the activity stability is significantly improved, and the residual amount of Cd element in reaction solution is reduced ∼8 times over TNT-GR-CdS. Various measurements of photoelectrochemistry and radicals reveal that the enhanced photoactivity and photostabilities of TNT-GR-CdS are due to the efficient spatial separation of the photogenerated electron-hole pairs and the restricted photocorrosion of CdS via an efficient Z-scheme mechanism under simulated sunlight. PMID:25058472

  3. Effect of phosphonate monolayer adsorbate on the microwave photoresponse of TiO2 nanotube membranes mounted on a planar double ring resonator.

    PubMed

    Zarifi, Mohammad H; Farsinezhad, Samira; Wiltshire, Benjamin D; Abdorrazaghi, Mohammad; Najia Mahdi; Kar, Piyush; Daneshmand, Mojgan; Shankar, Karthik

    2016-09-16

    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.

  4. 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.

  5. Effect of phosphonate monolayer adsorbate on the microwave photoresponse of TiO2 nanotube membranes mounted on a planar double ring resonator.

    PubMed

    Zarifi, Mohammad H; Farsinezhad, Samira; Wiltshire, Benjamin D; Abdorrazaghi, Mohammad; Najia Mahdi; Kar, Piyush; Daneshmand, Mojgan; Shankar, Karthik

    2016-09-16

    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. PMID:27487465

  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. Gold nanocluster-sensitized TiO2 nanotubes to enhance the photocatalytic hydrogen generation under visible light

    NASA Astrophysics Data System (ADS)

    Wang, Hongkai; Chen, Fuyi; Li, Weiyin; Tian, Tian

    2015-08-01

    The wide band-gap of TiO2 semiconductors hinders the photocatalytic hydrogen generation under visible light. In this research, we introduce glutathione-protected gold (Au-GSH) nanoclusters as a sensitizer to extend the active region of TiO2 up to a wavelength of 510 nm under visible light spectrum. We demonstrate that Au-GSH nanoclusters are capable of enhancing photocatalytic effects for hydrogen generation in photo-electrochemical cells (PECs). The combined effects of metal nanoclusters and sacrificial agent (EDTA) enhance the photocurrent up to six times more than what can be achieved using Au-GSH nanoclusters without EDTA. Moreover, the mechanisms of interaction between Au-GSH nanoclusters and EDTA have been investigated through instantaneous photoresponse measurements. A single electrode system has been designed to simplify PECs for hydrogen generation, which exhibits the same enhanced photocatalytic effect.

  8. 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.

  9. 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. PMID:25755072

  10. Synthesis, characterization, and photocatalytic activity of porous La-N-co-doped TiO2 nanotubes for gaseous chlorobenzene oxidation.

    PubMed

    Cheng, Zhuowei; Gu, Zhiqi; Chen, Jianmeng; Yu, Jianming; Zhou, Lingjun

    2016-08-01

    The photocatalytic oxidation of gaseous chlorobenzene (CB) by the 365nm-induced photocatalyst La/N-TiO2, synthesized via a sol-gel and hydrothermal method, was evaluated. Response surface methodology (RSM) was used to model and optimize the conditions for synthesis of the photocatalyst. The optimal photocatalyst was 1.2La/0.5N-TiO2 (0.5) and the effects of La/N on crystalline structure, particle morphology, surface element content, and other structural characteristics were investigated by XRD (X-ray diffraction), TEM (Transmission Electron Microscopy), FTIR (Fourier transform infrared spectroscopy), UV-vis (Ultraviolet-visible spectroscopy), and BET (Brunauer Emmett Teller). Greater surface area and smaller particle size were produced with the co-doped TiO2 nanotubes than with reference TiO2. The removal of CB was effective when performed using the synthesized photocatalyst, though it was less efficient at higher initial CB concentrations. Various modified Langmuir-Hinshelwood kinetic models involving the adsorption of chlorobenzene and water on different active sites were evaluated. Fitting results suggested that competitive adsorption caused by water molecules could not be neglected, especially for environments with high relative humidity. The reaction intermediates found after GC-MS (Gas chromatography-mass spectrometry) analysis indicated that most were soluble, low-toxicity, or both. The results demonstrated that the prepared photocatalyst had high activity for VOC (volatile organic compounds) conversion and may be used as a pretreatment prior to biopurification. PMID:27521952

  11. Synergistic effect of TiCl4-ZnO treated TiO2 nanotubes in dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Lee, Jin Soo; Kim, Kyung Hwan; Kim, Chang Seob; Choi, Hyung Wook

    2015-06-01

    Oxide semiconducting TiO2 nanoparticles (TNPs) with TiO2 nanotubes (TNTs) have attracted considerable attention because of a fast electron migration process in the photoelectrode. However, TNT films of dye-sensitized solar cells (DSSCs) displayed low conversion efficiency because of lower dye loading and sunlight absorption than in the case of TNPs films. For high-performance DSSCs, an aqueous solution treatment using titanium tetrachloride (TiCl4) and zinc oxide (ZnO) was used on the TNT film. The TNT array was prepared by an anodization process. Herein, we studied that a double dip-coating TiCl4-ZnO treatment of the TNTs enhanced photocurrent density and fill factor due to an improvement in electron transfer, increase in dye adsorption, and reduction in the recombination charge rate. The results show that the DSSCs with a TiCl4-ZnO treatment show a maximum conversion efficiency of 8.29% and JSC of 21.19 mA/cm2 under a simulated solar light irradiation of 100 mW/cm2 (AM 1.5).

  12. 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.

  13. Air-gating and chemical-gating in transistors and sensing devices made from hollow TiO2 semiconductor nanotubes

    NASA Astrophysics Data System (ADS)

    Alivov, Yahya; Funke, Hans; Nagpal, Prashant

    2015-07-01

    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 1-106. 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.

  14. Enhanced photoelectrochemical water splitting performance of TiO2 nanotube arrays coated with an ultrathin nitrogen-doped carbon film by molecular layer deposition

    NASA Astrophysics Data System (ADS)

    Tong, Xili; Yang, Peng; Wang, Yunwei; Qin, Yong; Guo, Xiangyun

    2014-05-01

    Vertically oriented TiO2 nanotube arrays (TNTAs) were conformally coated with an ultrathin nitrogen-doped (N-doped) carbon film via the carbonization of a polyimide film deposited by molecular layer deposition and simultaneously hydrogenated, thereby creating a core/shell nanostructure with a precisely controllable shell thickness. The core/shell nanostructure provides a larger heterojunction interface to substantially reduce the recombination of photogenerated electron-hole pairs, and hydrogenation enhances solar absorption of TNTAs. In addition, the N-doped carbon film coating acts as a high catalytic active surface for oxygen evolution reaction, as well as a protective film to prevent hydrogen-treated TiO2 nanotube oxidation by electrolyte or air. As a result, the N-doped carbon film coated TNTAs displayed remarkably improved photocurrent and photostability. The TNTAs with a N-doped carbon film of ~1 nm produces a current density of 3.6 mA cm-2 at 0 V vs. Ag/AgCl under the illumination of AM 1.5G (100 mW cm-2), which represents one of the highest values achieved with modified TNTAs. Therefore, we propose that ultrathin N-doped carbon film coating on materials is a viable approach to enhance their PEC water splitting performance.Vertically oriented TiO2 nanotube arrays (TNTAs) were conformally coated with an ultrathin nitrogen-doped (N-doped) carbon film via the carbonization of a polyimide film deposited by molecular layer deposition and simultaneously hydrogenated, thereby creating a core/shell nanostructure with a precisely controllable shell thickness. The core/shell nanostructure provides a larger heterojunction interface to substantially reduce the recombination of photogenerated electron-hole pairs, and hydrogenation enhances solar absorption of TNTAs. In addition, the N-doped carbon film coating acts as a high catalytic active surface for oxygen evolution reaction, as well as a protective film to prevent hydrogen-treated TiO2 nanotube oxidation by

  15. Selective formation of ordered arrays of octacalcium phosphate ribbons on TiO(2) nanotube surface by template-assisted electrodeposition.

    PubMed

    Lai, Yuekun; Huang, Yongxia; Wang, Hui; Huang, Jianying; Chen, Zhong; Lin, Changjian

    2010-03-01

    Using a patterned superhydrophobicity/superhydrophilicity template, micropatterned octacalcium phosphate (OCP) has been successfully fabricated on TiO(2) nanotube array surface. The resultant OCP micropattern has been characterized with scanning electron microscopy, optical microscopy, X-ray diffraction and electron probe microanalyzer. It is shown that the ribbon-like OCP crystals possess a highly ordered and hierarchically porous structure at nano-micro-scales. They can be selectively grown at superhydrophilic areas which are confined by the hydrophobic regions. The high wetting contrast template proves to be useful for constructing well-defined dual scale OCP film with porous structure biomimic to natural bone. A mechanism has been proposed to explain the formation of the OCP patterned film with hierarchically porous structure and distinct selectivity.

  16. Role of structural H 2O in TiO 2 nanotubes in enhancing Pt/C direct ethanol fuel cell anode electro-catalysts

    NASA Astrophysics Data System (ADS)

    Song, Huanqiao; Qiu, Xinping; Guo, Daojun; Li, Fushen

    TiO 2 nanotubes (TNTs) with different structural water were obtained by heat treatment under different temperatures. The role of the structural water in TNTs co-catalyzing ethanol oxidation with Pt/C catalyst was studied systematically. Electrochemical studies using cyclic voltammetry and CO stripping voltammetry indicated that more structural water in TNTs was favorable for improving the tolerance of Pt/C to poisoning species; while chronoamperometry curves and repeated cyclic voltammograms showed that slightly less structural water in TNTs actually led to higher catalytic activity and better stability of Pt/C catalysts for ethanol oxidation. This strange result has been analyzed and was ascribed to the appropriate balance of bi-functional mechanism and ethanol transfer in the catalyst layer with less structural water.

  17. 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. PMID:22902130

  18. 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

  19. 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. PMID:26344299

  20. 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.

  1. A Novel Method for the Preparation of CdS Quantum Dots Sensitized Solar Cells Based on Free-Standing and Through-Hole TiO2 Nanotube Arrays.

    PubMed

    Wang, Yang; Li, Zhen; Li, Fei; Tian, Yunfeng; Zhao, Wen; Liu, Xueqin; Yang, Jianbo

    2016-06-01

    The crystallized free-standing through-hole TiO2 nanotube arrays (TNAs) membranes were fabricated by a facile method. CdS quantum dots (QDs) are assembled onto free-standing through-hole NTAs films using successive ionic layer adsorption and reaction (SILAR) process. The CdS/TNAs were easily transferred to the fluorine-doped tin oxide glass to form photoanodes after they were sensitized by modifying the traditional procedure. The morphology and crystalline phase of the TiO2 nanotubes were studied by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The cells with 5 SILAR cycles show photovoltaic conversion efficiency as high as 3.34% under simulated sunlight (AM 1.5, 100 mW x cm(-2)). Obviously, the new approach promotes the uniform distribution of CdS on the densely aligned TNAs and prevents the clogging of CdS quantum dots (QDs) at the TiO2 nanotube mouth. Such enhanced properties may be ascribed to the strong combination between CdS and TiO2, favorable for charge separation of TNAs. PMID:27427675

  2. 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. PMID:24846604

  3. TiO2 nanotubes as solid-phase extraction adsorbent for the determination of polycyclic aromatic hydrocarbons in environmental water samples.

    PubMed

    Kefi, Bochra Bejaoui; El Atrache, Latifa Latrous; Kochkar, Hafedh; Ghorbel, Abdelhamid

    2011-01-01

    An analytical method based on TiO2 nanotubes solid-phase extraction (SPE) combined with gas chromatography (GC) was established for the analysis of seven polycyclic aromatic hydrocarbons (PAHs): acenaphtylene, acenaphthene, anthracene, fluorene, phenanthrene, fluoranthene and pyrene. Factors affecting the extraction efficiency including the eluent type and its volume, adsorbent amount, sample volume, sample pH and sample flow rate were optimized. The characteristic data of analytical performance were determined to investigate the sensitivity and precision of the method. Under the optimized extraction conditions, the method showed good linearity in the range of 0.01-0.8 microg/mL, repeatability of the extraction (RSD were between 6.7% and 13.5%, n = 5) and satisfactory detection limits (0.017-0.059 ng/mL). The developed method was successfully applied to the analysis of surface water (tap, river and dam) samples. The recoveries of PAHs spiked in environmental water samples ranged from 90% to 100%. All the results indicated the potential application of titanate nanotubes as solid-phase extraction adsorbents to pre-treat water samples.

  4. 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.

  5. Polyaniline nanotubes coated with TiO2&γ-Fe2O3@graphene oxide as a novel and effective visible light photocatalyst for removal of rhodamine B from water

    NASA Astrophysics Data System (ADS)

    Ghavami, Monireh; Kassaee, Mohammad Zaman; Mohammadi, Reza; Koohi, Maryam; Haerizadeh, Bibi Narjes

    2014-12-01

    Synthesis of polyaniline-nanotubes (PANI-NT), in the presence of TiO2 and γ-Fe2O3 functionalized graphene oxide (GO), gives a green and magnetically recyclable photocatalyst, TiO2&γ-Fe2O3@GO/PANI-NT. The later orchestrates 94% photocatalytic efficiency in removal of rhodamine B (RB) from water, under simulated solar light irradiation. This is far higher than the 36% observed in the presence of TiO2&γ-Fe2O3@GO alone, where PANI-NT is excluded from the structure. Morphology, composition, and structural properties of our economically sound photocatalyst are characterized by X-ray diffraction, energy-dispersive X-ray spectroscopy, thermo-gravimetric, transmission electron microscopy, inductively coupled plasma, RAMAN and Fourier-transform infrared spectroscopy.

  6. 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

  7. Domain-confined catalytic soot combustion over Co3O4 anchored on a TiO2 nanotube array catalyst prepared by mercaptoacetic acid induced surface-grafting

    NASA Astrophysics Data System (ADS)

    Ren, Jiale; Yu, Yifu; Dai, Fangfang; Meng, Ming; Zhang, Jing; Zheng, Lirong; Hu, Tiandou

    2013-11-01

    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).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). Electronic supplementary information (ESI) available: The images of XRD, UV-vis, EDX and soot-TPR. The table providing information on Co/Ti-NA catalysts. See DOI: 10.1039/c3nr03757f

  8. Effect of pH value on H2Ti2O5/TiO2 composite nanotubes as Pt catalyst support for methanol oxidation

    NASA Astrophysics Data System (ADS)

    Sui, Xu-Lei; Wang, Zhen-Bo; Li, Cun-Zhi; Zhang, Jing-Jia; Zhao, Lei; Gu, Da-Ming

    2014-12-01

    Hydrogenotitanate/titania composite nanotubes (HTNTs) are synthesized from anatase titania power via hydrothermal process at various pH values of acid treatment. The change of HTNTs components is investigated in detail by X-ray diffraction (XRD), energy dispersive analysis of X-ray (EDAX), which reveal that the products are gradually converted from "H2Ti2O5·H2O" phase to "anatase TiO2" phase with the decrease of pH values. Pt based catalysts are prepared by microwave-assisted ethylene glycol method. The effects of pH values on the performance of Pt/C-HTNTs catalysts have been mainly investigated. It has been found that the distribution and electrocatalytic properties of platinum nanoparticles are sensitive to the pH value of acid treatment. The Pt/C-HTNTs catalyst prepared at the acid treatment pH value of 7 exhibits the better electrochemical activity and stability than other catalysts.

  9. 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. PMID:25884048

  10. Enhanced photocatalytic degradation activity over TiO2 nanotubes co-sensitized by reduced graphene oxide and copper(II) meso-tetra(4-carboxyphenyl)porphyrin

    NASA Astrophysics Data System (ADS)

    Wei, Meng; Wan, Junmin; Hu, Zhiwen; Peng, Zhiqin; Wang, Bing

    2016-07-01

    In this paper, TiO2 nanotubes (TNT) co-sensitized with copper(II) meso-tetra(4-carboxyphenyl)porphyrin (CuTCPP) and reduced graphene oxide nanosheets (rGO), which was fabricated through two-step improved hydrothermal method and heating reflux process. The effect of rGO and CuTCPP on the co-photocatalytic behavior of TNT for the degradation of Methylene Blue (MB) were measured under visible light irradiation. The photocatalysts have been characterized and analyzed by high-resolution transmission electron microscopy (TEM), selected area electronic diffraction (SAED), elemental mapping by energy-dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) and electron paramagnetic resonance (EPR). The results provide a deeper insight into the co-photocatalytic mechanism of CuTCPP/rGO-TNT nanocomposites. The degradation results showed a purification of more than 95% MB in wastewater, which is about 5 times higher than that of the pure TNT. The results also confirm the prepared CuTCPP/rGO-TNT nanocomposites possess superior co-photocatalytic activities.

  11. A co-immobilized mediator and microorganism mediated method combined pretreatment by TiO2 nanotubes used for BOD measurement.

    PubMed

    Liu, Ling; Zhang, Shengsen; Xing, Li; Zhao, Huijun; Dong, Shaojun

    2012-05-15

    In this paper, we proposed a method by using co-immobilized Escherichia coli (E. coli) as a biocatalyst and neutral red (NR) as an artificial electronic acceptor to modify glassy carbon electrode (GCE) for biochemical oxygen demand (BOD) measurement. Two different modification approaches of GCE were utilized and compared. In one approach, NR was electropolymerized on the surface of GCE, and E. coli cells were mixed with grafting copolymer PVA-g-PVP (briefly gPVP) and covered on NR polymer film to obtain a (gPVP/E. coli)/PNR/GCE. In the second approach, both NR and E. coli cells were mixed with the copolymer gPVP and modified GCE, after drying, which was electrochemically treated similar as above for obtaining a (gPVP/E. coli/NR)p/GCE. Based on the electrochemical evaluation, the performance of the latter was better, which may be caused by that the NR deposited on the surface of E. coli resulting in a good electron transport and permeability of cells membrane. To develop the results obtained at (gPVP/E. coli/NR)p/GCE further, the pretreatment by TiO(2) nanotubes arrays (TNTs) was employed, and different effects on samples of GGA, OECD, urea and real wastewater were evaluated. These results suggest that the present method holds a potential application for rapid BOD biosensor.

  12. TiO2 nanotube array photoelectrocatalyst and Ni-Sb-SnO2 electrocatalyst bifacial electrodes: a new type of bifunctional hybrid platform for water treatment.

    PubMed

    Yang, So Young; Choi, Wonyong; Park, Hyunwoong

    2015-01-28

    Bifunctional hybrid electrodes capable of generating various reactive oxygen species (ROS) over a wide range of potentials were developed by coupling electrocatalysts and photoelectrocatalysts. To achieve this, Ni-doped Sb-SnO2 (NSS) was deposited on one side of a titanium (Ti) foil while the other side was anodized to grow a TiO2 nanotube array (TNA) for electrochemical ozone generation and photoelectrochemical hydroxyl radical generation, respectively. Surface characterization indicated that NSS and TNA were formed and spatially separated yet electrically connected through the Ti substrate. While each catalyst possessed unique electrochemical properties, the coupling of both catalysts resulted in mixed electrochemical properties that drove electrocatalysis at high potentials and photoelectrocatalysis at low potentials. The performance of the NSS/TNA electrode for phenol decomposition was ∼3 times greater than that of single-layer catalysts and ∼1.5 times greater than the combined catalytic performances of the individual NSS and TNA catalysts. This synergistic effect was attributed partly to the simultaneous generation of hydroxyl radicals and ozone, followed by the production of other ROS. A mechanism for the generation of ROS was discussed.

  13. 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.

  14. Low-temperature liquid phase reduced TiO2 nanotube arrays: synergy of morphology manipulation and oxygen vacancy doping for enhancement of field emission.

    PubMed

    Zhang, Xu-Qiang; Chen, Jian-Biao; Wang, Cheng-Wei; Liao, Ai-Zhen; Su, Xiao-Feng

    2015-05-01

    The partially reduced TiO(2) nanotube arrays (TNAs) are prepared via an uncomplicated and low-cost liquid phase reduction strategy using NaBH(4) as the reducing agent. By controlling and adjusting the reduction temperatures from 30 to 90 °C, the reduction treatment can not only change their surface morphology but also introduce oxygen vacancies into them, resulting in an optimized morphology, elevated Fermi-level, reduced effective work function and improved conductivity of the TNAs. Meanwhile, the thermal and long-term stability of oxygen vacancy are also investigated, indicating that the oxygen vacancies retain long-term stability from room temperature up to 150 °C. More interesting, partially reduced TNAs show drastically enhanced field emission (FE) performances including substantially decreased turn-on field from 18.86 to 1.53 V μm(-1), a high current density of 4.00 mA cm(-2) at 4.52 V μm(-1), and an excellent FE stability and repeatability. These very promising results are attributed to the combination of the optimized morphology and introduced oxygen vacancies, which can increase FE sites, reduce effective work function and increase conductivity.

  15. 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.

  16. TiO2 nanotube array photoelectrocatalyst and Ni-Sb-SnO2 electrocatalyst bifacial electrodes: a new type of bifunctional hybrid platform for water treatment.

    PubMed

    Yang, So Young; Choi, Wonyong; Park, Hyunwoong

    2015-01-28

    Bifunctional hybrid electrodes capable of generating various reactive oxygen species (ROS) over a wide range of potentials were developed by coupling electrocatalysts and photoelectrocatalysts. To achieve this, Ni-doped Sb-SnO2 (NSS) was deposited on one side of a titanium (Ti) foil while the other side was anodized to grow a TiO2 nanotube array (TNA) for electrochemical ozone generation and photoelectrochemical hydroxyl radical generation, respectively. Surface characterization indicated that NSS and TNA were formed and spatially separated yet electrically connected through the Ti substrate. While each catalyst possessed unique electrochemical properties, the coupling of both catalysts resulted in mixed electrochemical properties that drove electrocatalysis at high potentials and photoelectrocatalysis at low potentials. The performance of the NSS/TNA electrode for phenol decomposition was ∼3 times greater than that of single-layer catalysts and ∼1.5 times greater than the combined catalytic performances of the individual NSS and TNA catalysts. This synergistic effect was attributed partly to the simultaneous generation of hydroxyl radicals and ozone, followed by the production of other ROS. A mechanism for the generation of ROS was discussed. PMID:25561436

  17. 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.

  18. 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

    2016-05-01

    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.

  19. In situ enzymatic ascorbic acid production as electron donor for CdS quantum dots equipped TiO2 nanotubes: a general and efficient approach for new photoelectrochemical immunoassay.

    PubMed

    Zhao, Wei-Wei; Ma, Zheng-Yuan; Yan, Dong-Yang; Xu, Jing-Juan; Chen, Hong-Yuan

    2012-12-18

    In this work, a novel photoelectrochemical (PEC) immunoanalysis format was developed for sensitive and specific detection of prostate-specific antigen (PSA) based on an in situ electron donor producing approach. Thioglycolic acid-capped CdS quantum dots (QDs) equipped TiO(2) nanotubes (NTs) were fabricated via a facile electrostatic adsorption method. The coupling of CdS QDs and TiO(2) NTs results in an enhanced excitation and photo-to-electric conversion efficiency. Using alkaline phosphatase catalytic chemistry to in situ generate ascorbic acid for electron donating, an exquisite immunosandwich protocol was successfully constructed for the PSA assay due to the dependence of the photocurrent signal on the concentration of electron donor. This work opens a different perspective for transducer design in PEC detection and provides a general format for future development of PEC immunoanalysis.

  20. 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. PMID:19560182

  1. 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.

  2. TiO2-graphene nanocomposites for gas-phase photocatalytic degradation of volatile aromatic pollutant: is TiO2-graphene truly different from other TiO2-carbon composite materials?

    PubMed

    Zhang, Yanhui; Tang, Zi-Rong; Fu, Xianzhi; Xu, Yi-Jun

    2010-12-28

    The nanocomposites of TiO(2)-graphene (TiO(2)-GR) have been prepared via a facile hydrothermal reaction of graphene oxide and TiO(2) in an ethanol-water solvent. We show that such a TiO(2)-GR nanocomposite exhibits much higher photocatalytic activity and stability than bare TiO(2) toward the gas-phase degradation of benzene, a volatile aromatic pollutant in air. By investigating the effect of different addition ratios of graphene on the photocatalytic activity of TiO(2)-GR systematically, we find that the higher weight ratio in TiO(2)-GR will decrease the photocatalytic activity. Analogous phenomenon is also observed for the liquid-phase degradation of dyes over TiO(2)-GR. In addition, the key features for TiO(2)-GR including enhancement of adsorptivity of pollutants, light absorption intensity, electron-hole pairs lifetime, and extended light absorption range have also been found in the composite of TiO(2) and carbon nanotubes (TiO(2)-CNT). These strongly manifest that TiO(2)-GR is in essence the same as other TiO(2)-carbon (carbon nanotubes, fullerenes, and activated carbon) composite materials on enhancement of photocatalytic activity of TiO(2), although graphene by itself has unique structural and electronic properties. Notably, this key fundamental question remains completely unaddressed in a recent report ( ACS Nano 2010 , 4 , 380 ) regarding liquid-phase degradation of dyes over the TiO(2)-GR photocatalyst. Thus, we propose that TiO(2)-GR cannot provide truly new insights into the fabrication of TiO(2)-carbon composite as high-performance photocatalysts. It is hoped that our work could avert the misleading message to the readership, hence offering a valuable source of reference on fabricating TiO(2)-carbon composites for their application as a photocatalyst in the environment cleanup. PMID:21117654

  3. 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.

  4. 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. PMID:27285731

  5. 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.

  6. Structural investigations of hybrid TiO2/CNTs nanomaterials.

    PubMed

    Lin, Kuan-Nan; Liou, Wei-Jen; Lin, Hong-Ming; Yang, Tsung-Yeh; Lin, Chung-Kwei

    2010-05-01

    In the present study, pure TiO2 and hybrid TiO2/CNTs nanomaterials are prepared by sol gel technique. Post heat treatment is performed at 600, 800, and 1000 degrees C, respectively. The structural characterizations are performed by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction and synchrotron X-ray absorption spectroscopy techniques. Experimental results show that anatase to rutile transformation can be observed for pure TiO2 nanomaterials after heat treatment at 800 degrees C. The anatase to rutile transformation is inhibited by carbon nanotubes, and therefore only anatase phases for TiO2 nanomaterials can be observed in the hybrid nanomaterials. The 600 degrees C hybrid nanomaterials show a microstructure with CNTs covered by continuous TiO2 films of numerous small nanoparticles. After applying heat treatment on the hybrid nanomaterials at 1000 degrees C, only TiO2 nanoparticles adhere individually to the uncovered CNTs. Though all hybrid nanomaterials exhibit anatase TiO2, synchrotron X-ray absorption spectra investigations reveal that hybrid TiO2/CNTs exhibit different electronic properties as compared to those of pure TiO2 nanomaterials.

  7. Incorporation Of Nanocrystalline Silver on Carbon Nanotubes by Electrodeposition Technique

    NASA Astrophysics Data System (ADS)

    Hussain, S.; Pal, A. K.

    2008-10-01

    Nanocrystalline silver incorporated carbon nanotubes were grown on Si (001) substrate from an electrolytic bath containing acetonitrile (1% v/v) and water with appropriate amount of silver acetate at an applied d.c. potential ˜20V. The films were characterized by measuring their microstructural properties, FTIR and Raman studies. HRTEM image indicated that the diameter of the nanotubes as ˜5 nm and the d spacing as ˜0.34 nm for (002) plane of CNT. With the addition of nanocrystalline silver, the intensity of G-band decreases while the D-band located ˜1352 cm-1 becomes sharper.

  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. Synthesis of rare earth doped TiO2 nanorods as photocatalysts for lignin degradation.

    PubMed

    Song, Liang; Zhao, Xueyuan; Cao, Lixin; Moon, Ji-Won; Gu, Baohua; Wang, Wei

    2015-10-28

    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-TiO2 NRs are among the best for degrading MO, with an observed rate constant of 4.2 × 10(-3) s(-1). The La(3+), Sm(3+), Eu(3+) and Er(3+) doped TiO2 NRs also showed higher photocatalytic efficiencies in degrading MO than the commercial P25 TiO2. 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. PMID:26400095

  10. Synthesis of rare earth doped TiO2 nanorods as photocatalysts for lignin degradation

    DOE PAGESBeta

    Song, Liang; Zhao, Xueyuan; Cao, Lixin; Moon, Ji-Won; Gu, Baohua; Wang, Wei

    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. Synthesis of rare earth doped TiO2 nanorods as photocatalysts for lignin degradation.

    PubMed

    Song, Liang; Zhao, Xueyuan; Cao, Lixin; Moon, Ji-Won; Gu, Baohua; Wang, Wei

    2015-10-28

    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-TiO2 NRs are among the best for degrading MO, with an observed rate constant of 4.2 × 10(-3) s(-1). The La(3+), Sm(3+), Eu(3+) and Er(3+) doped TiO2 NRs also showed higher photocatalytic efficiencies in degrading MO than the commercial P25 TiO2. 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.

  12. 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.

  13. 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.

  14. A facile strategy to fabricate high-quality single crystalline brookite TiO2 nanoarrays and their photoelectrochemical properties

    NASA Astrophysics Data System (ADS)

    Choi, Mingi; Yong, Kijung

    2014-10-01

    Vertically aligned high-quality single crystalline brookite TiO2 nanoarrays were synthesized for the first time using an environmentally benign one-step hydrothermal reaction. They have a unique bullet-shaped structure which has a length of 700-1000 nm and a width of 150-250 nm with a sharpened tip structure. By adjusting the concentration of NaOH in hydrothermal reaction, we could also synthesize other types of TiO2 nanostructures including anatase TiO2 nanotubes/nanowires. The morphologies and crystal structures of the products were confirmed by scanning electron microscopy, transmission electron microscopy and X-ray diffraction analysis. Their vertically aligned structures facilitate their application as photoanodes in photoelectrochemical cells, and the photoelectrochemical properties such as photocurrent density and open circuit voltage were measured in a three-electrode electrochemical cell with TiO2 nanoarrays, Ag/AgCl and a Pt flag as the working, reference and counter electrodes, respectively, incorporating a 0.1 M NaOH electrolyte solution. The fabricated brookite TiO2 nanoarrays exhibited a highly enhanced photocurrent density and a longer electron lifetime compared with anatase TiO2 nanoarrays with similar lengths.Vertically aligned high-quality single crystalline brookite TiO2 nanoarrays were synthesized for the first time using an environmentally benign one-step hydrothermal reaction. They have a unique bullet-shaped structure which has a length of 700-1000 nm and a width of 150-250 nm with a sharpened tip structure. By adjusting the concentration of NaOH in hydrothermal reaction, we could also synthesize other types of TiO2 nanostructures including anatase TiO2 nanotubes/nanowires. The morphologies and crystal structures of the products were confirmed by scanning electron microscopy, transmission electron microscopy and X-ray diffraction analysis. Their vertically aligned structures facilitate their application as photoanodes in photoelectrochemical

  15. A facile method to prepare SnO2 nanotubes for use in efficient SnO2-TiO2 core-shell dye-sensitized solar cells.

    PubMed

    Gao, Caitian; Li, Xiaodong; Lu, Bingan; Chen, Lulu; Wang, Youqing; Teng, Feng; Wang, Jiangtao; Zhang, Zhenxing; Pan, Xiaojun; Xie, Erqing

    2012-06-01

    A high-efficiency photoelectrode for dye-sensitized solar cells (DSSCs) should combine the advantageous features of fast electron transport, slow interfacial electron recombination and large specific surface area. However, these three requirements usually cannot be achieved simultaneously in the present state-of-the-art research. Here we report a simple procedure to combine the three conflicting requirements by using porous SnO(2) nanotube-TiO(2) (SnO(2) NT-TiO(2)) core-shell structured photoanodes for DSSCs. The SnO(2) nanotubes are prepared by electrospinning of polyvinyl pyrrolidone (PVP)/tin dichloride dihydrate (SnCl(2)·2H(2)O) solution followed by direct sintering of the as-spun nanofibers. A possible evolution mechanism is proposed. The power conversion efficiency (PCE) value of the SnO(2) NT-TiO(2) core-shell structured DSSCs (∼5.11%) is above five times higher than that of SnO(2) nanotube (SnO(2) NT) DSSCs (∼0.99%). This PCE value is also higher than that of TiO(2) nanoparticles (P25) DSSCs (∼4.82%), even though the amount of dye molecules adsorbed to the SnO(2) NT-TiO(2) photoanode is less than half of that in the P25 film. This simple procedure provides a new approach to achieve the three conflicting requirements simultaneously, which has been demonstrated as a promising strategy to obtain high-efficiency DSSCs. PMID:22572999

  16. 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. PMID:26635472

  17. 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. PMID:20170759

  18. 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

  19. 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.

  20. Photocatalytic Water-Splitting Characteristic of Electric Reduced Black TiO2 Nanorods

    NASA Astrophysics Data System (ADS)

    Yun, Jong-Won; Ryu, Ki Yeon; Kim, Sunho; Jang, Se-Jung; Kim, Yong Soo

    In various reduction methods of TiO2, the electric reduction could apply to anodized TiO2 nanotube. However, it is not suitable to reduce TiO2 nanorods(NRs) grown on fluorine doped tin oxide (FTO) substrate using hydrothermal method, because those are easily peeled off due to lattice mismatching between FTO and TiO2 NRs. In this talk, we will demonstrate electric reduced-black TiO2 NRs with strong adhesion on FTO substrate for an effective visible photocatalyst. To fabricate the reduced-black TiO2 NRs, we firstly deposited TiO2 seed layer on FTO glass using RF-sputtering for mitigating the exfoliation, then grow TiO2 NRs with hydrothermal method. Finally, TiO2 NRs were reduced with electric bias. The final reduced-black TiO2 NRs exhibit a higher photocurrent density, 0.9 mA/cm2 in comparison with pure-TiO2 NRs. This result indicates that our reduced-black TiO2 NRs has lower bandgap with modified valance band position and enhance the surface reactivity with oxygen defect generation. This research was supported by Priority Research Centers Program (2009-0093818), the Basic Science Research Program (2015-019609) and Basic Research Lab Program (2014-071686) through National Research Foundation of Korea (NRF) funded by the Korean government.

  1. 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.

  2. 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.

  3. Solvothermal Process Assisted Sensitization of 1D Anodized TiO2 Nanotubes with 0D Cadmium Chalcogenides (CdTe, CdS) for Efficient Solar to Clean Energy Generation

    NASA Astrophysics Data System (ADS)

    Sarker, Swagotom

    The creation of an n-n heterojunction between TiO2 nanotubes (T_NT) and CdTe nanocrystals (which mostly exist as p-type) is crucial for realizing the benefits of efficient directional charge transport in a photoanode of 1D/0D architecture. The presented one-pot solvothermal approach leverages temperature control to achieve linker-free spatial distribution of CdTe nanocrystals (NCs) on T_NT resulting in highly efficient optical and photoelectrochemical responses. As a result of this positive outcome, a comparative study between the solvothermal approach and the linker mediated approach was performed on water oxidation with CdS NC decorated T_NT. Solvothermally synthesized T_NT/CdS photoelectrode presents ˜600% higher value of short-circuit current density (Isc) than that of the plain T_NT (0.95 mA/cm2); in addition, it demonstrates 4.20-fold increased applied-bias-to photoconversion efficiency (ABPE) in comparison with the lone T_NT (0.77%). However, linker mediated T_NT/MPA-CdS photoelectrode exhibits relatively lower value of I sc (2.51 mA/cm2) and ABPE (1.79 %).

  4. 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

    2013-09-01

    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.

  5. 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.

  6. 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. PMID:25458670

  7. Photocatalytic activity of TiO2 nanomaterials for methylene blue dye degradation

    NASA Astrophysics Data System (ADS)

    Lee, Deuk Yong; Son, Siwon; Jeon, Min-Seok; Lee, Myung-Hyun; Kim, Bae-Yeon

    2016-04-01

    TiO2 nanomaterials were prepared by a sol-gel derived electrospinning, calcination from 500°C to 650°C, and subsequent mechanical grinding to investigate the effect of calcination temperature on crystal structure, crystallinity, and photocatalytic activity of methylene blue (MB). XRD results indicated that TiO2 nanorods calcined at 500°C is composed of anatase TiO2 only. However, mixed crystals of anatase and rutile were observed for TiO2 calcined above 550°C. Higher MB degradation was found for the TiO2 nanorods calcined at 550°C probably due to the mixed crystals and larger surface area. However, the improved photocatalytic activity was achieved for TiO2 nanotube due to the synergic combinations of mixed crystals, larger specific surface area, and light trapping effect.

  8. 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.

  9. 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.

  10. Formation of TiO2 nanotube arrays by anodic oxidation in LiOH added ethylene glycol electrolyte and the effect of thermal annealing on the photoelectrochemical properties

    NASA Astrophysics Data System (ADS)

    Taib, Mustaffa Ali Azhar; Tan, Wai Kian; Okuno, Teruhisa; Kawamura, Go; Jaafar, Mariatti; Razak, Khairunisak Abdul; Matsuda, Atsunori; Lockman, Zainovia

    2016-07-01

    The present study employs LiOH as an additive in fluoride ethylene glycol (EG) electrolyte (LiOH/EG) for anodic oxidation of Ti in fabricating anodic TiO2 nanotubes (TNTs). TNTs formed in LiOH/EG electrolyte were found to be longer (6.23 ± 0.2 µm) compared to when only water was used in EG electrolyte: 4.54 ± 0.2 µm for the same anodisation time of 30 min and voltage of 60 V. The as-anodised TNTs were however amorphous. Hence, the samples were annealed at high temperatures for crystallization preferably as anatase oxide. Anatase phase is needed as the anodised Ti is used as a photoanode in a photoelectrochemical (PEC) cell. The effect of annealing temperatures on the TNTs to the photocurrent measurement was investigated in a standard KOH PEC cell under visible light illumination. Anodised Ti annealed at 200 °C has the lowest photocurrent of 0.002 mA cm-2. Sample annealed at 400 °C has the highest photocurrent of 0.955 mA cm-2 (0.5 V) since it is comprised of mostly anatase with crystallite size of 31.80 nm, whereas sample annealed at 600 °C seems to be a mixture of anatase and rutile, displays lower photocurrent of 0.823 mA cm-2. It was also observed that the as-anodised sample has slightly higher photocurrent than the 200 °C annealed sample perhaps due to the adsorbed OH species from the electrolyte acting as holes trapping sites.

  11. Photocatalytic Properties of TiO2 Porous Network Film.

    PubMed

    Yu, Lianqing; Zhi, Qianqian; Huang, Chengxing; Zhang, Yaping; Dong, Kaituo; Neppolian, B

    2015-09-01

    Three-dimensional porous network TiO2 film (PW-film) and nanoparticles film were synthesized on surface of the Ti foil by a facile method to investigate both the photoelectrochemical and photocatalytic properties. The prepared samples were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray diffraction spectroscopy (XRD) techniques. Methylene blue was used as a target molecule to estimate the photocatalytic activity of the films. Results revealed that the hydrothermal temperature and time have great influence on the crystal type and film morphology of TiO2 catalysts. A higher hydrothermal temperature is benefit for the formation of anatase phase of TiO2 nanotubes with PW-film, which had a large number of nodes. After investigation of the photoelectrochemical properties, a maximum photoconversion efficiency of 4.79% is observed for nanoparticles film with rutile phase of TiO2 under UV light illumination, which was incredible 2 times higher than that of the PW-film with anatase phase. It was shown that the morphology of TiO2 film contributes more significant effect on photocatalytic and photoelectric performance than its crystal type. PMID:26716214

  12. Photocatalytic Properties of TiO2 Porous Network Film.

    PubMed

    Yu, Lianqing; Zhi, Qianqian; Huang, Chengxing; Zhang, Yaping; Dong, Kaituo; Neppolian, B

    2015-09-01

    Three-dimensional porous network TiO2 film (PW-film) and nanoparticles film were synthesized on surface of the Ti foil by a facile method to investigate both the photoelectrochemical and photocatalytic properties. The prepared samples were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray diffraction spectroscopy (XRD) techniques. Methylene blue was used as a target molecule to estimate the photocatalytic activity of the films. Results revealed that the hydrothermal temperature and time have great influence on the crystal type and film morphology of TiO2 catalysts. A higher hydrothermal temperature is benefit for the formation of anatase phase of TiO2 nanotubes with PW-film, which had a large number of nodes. After investigation of the photoelectrochemical properties, a maximum photoconversion efficiency of 4.79% is observed for nanoparticles film with rutile phase of TiO2 under UV light illumination, which was incredible 2 times higher than that of the PW-film with anatase phase. It was shown that the morphology of TiO2 film contributes more significant effect on photocatalytic and photoelectric performance than its crystal type.

  13. Nano TiO2 Composite PVDF Polymer Electrolyte

    NASA Astrophysics Data System (ADS)

    Chiang, Chin-Yeh; Chu, Peter P.

    2002-12-01

    Physical and transport properties of lithium ion conducting polymer electrolyte formed by dispersing nanoscale particles and tubes of TiO2 into poly (vinyl dine fluoride) (PVDF) - lithium salt complexes are discussed. The composite in polymer is enhancing the interfacial interaction, ionic conductivity and mechanical strength due to the high surface area of the particle and the tube. DSC studies elucidate that both the crystallinity and melting temperatures of PVDF are decreased with increasing salt content. Blending with TiO2 particles also decreases melting temperature and crystallinity of PVDF, however nano-tube TiO2 shows even more dramatic effects compared to the particles in reducing PVDF crystallinity and the melting temperature. Even with the improved miscibility and higher salt dissociation, the ionic conductivities is reduced for the TiO2 nano particle composite, but increased about 20 fold in the nano-tube composite. The discrepancies are related to the difference of morphology as evidence from SEM micrograph.

  14. 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. PMID:25881329

  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. PMID:23425042

  16. 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

  17. Hydrogen Impurity Defects in Rutile TiO2

    NASA Astrophysics Data System (ADS)

    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

    2015-12-01

    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.

  18. Nitrogen doped TiO2 nano-particles: Phase control by solution combustion method

    NASA Astrophysics Data System (ADS)

    Bapna, Komal; Choudhary, R. J.; Phase, D. M.; Shastri, Sheetal; Prasad, R.; Ahuja, B. L.

    2016-05-01

    N-doped TiO2 nano powders were prepared by sol-gel solution combustion method. The influence of different fuels (urea and citric acid) used in obtaining N-TiO2 nano particles in similar conditions (heat treatment, amount of precursors) has been investigated. The growth of different phases of TiO2 (anatase and rutile) is strongly affected by the ligands and the dehydration reaction. Reduction in the band gap of TiO2 and features observed in the XPS spectra confirm the incorporation of N into TiO2 matrix.

  19. 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.

  20. 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.

  1. Sonochemical synthesis of TiO(2 nanoparticles on graphene for use as photocatalyst.

    PubMed

    Guo, Jingjing; Zhu, Shenmin; Chen, Zhixin; Li, Yao; Yu, Ziyong; Liu, Qinglei; Li, Jingbo; Feng, Chuanliang; Zhang, Di

    2011-09-01

    Using ultrasonication we succeed in a controlled incorporation of TiO(2) nanoparticles on the graphene layers homogeneously in a few hours. The average size of the TiO(2) nanoparticles was controlled at around 4-5 nm on the sheets without using any surfactant, which is attributed to the pyrolysis and condensation of the dissolved TiCl(4) into TiO(2) by ultrasonic waves. The photocatalytic activity of the resultant graphene-TiO(2) composites containing 25 wt.% TiO(2) is better than that of commercial pure TiO(2). This is partly due to the extremely small size of the TiO(2) nanoparticles and partly due to the graphene-TiO(2) composite structure consisting of homogeneous dispersion of crystalline TiO(2) nanoparticles on the graphene sheets. As the graphene in the composites has a very good contact with the TiO(2) nanoparticles it enhances the photo-electron conversion of TiO(2) by reducing the recombination of photo-generated electron-hole pairs. PMID:21482166

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. Ta2O5- and TiO2-based nanostructures made by atomic layer deposition.

    PubMed

    Kemell, Marianna; Härkönen, Emma; Pore, Viljami; Ritala, Mikko; Leskelä, Markku

    2010-01-22

    Nanotubular Ta(2)O(5)- and TiO(2)-based structures were prepared by atomic layer deposition of Ta(2)O(5) and TiO(2) thin films, conformally on pore walls of porous alumina membranes. Both self-supporting alumina membranes and Si-supported thin-film membranes were studied as templates. Long Ta(2)O(5) and TiO(2) nanotubes were prepared successfully with the self-supporting membranes. The TiO(2) nanotubes showed photocatalytic activity in methylene blue degradation under UV illumination. The Ta(2)O(5) and TiO(2) nanotubes were further modified by depositing Pt nanoparticles inside them. The Si-supported thin-film membranes were used as templates for the preparation of robust Ta(2)O(5)-coated Ni nanorod arrays on a Si substrate using electrodeposition, chemical etching and atomic layer deposition. In addition to photocatalysis, the nanostructures prepared in this work may find applications as other catalysts and as solid-state or electrochemical capacitors.

  8. The effects of functional magnetic nanotubes with incorporated nerve growth factor in neuronal differentiation of PC12 cells

    NASA Astrophysics Data System (ADS)

    Xie, Jining; Chen, Linfeng; Varadan, Vijay K.; Yancey, Justin; Srivatsan, Malathi

    2008-03-01

    In this in vitro study the efficiency of magnetic nanotubes to bind with nerve growth factor (NGF) and the ability of NGF-incorporated magnetic nanotubes to release the bound NGF are investigated using rat pheochromocytoma cells (PC12 cells). It is found that functional magnetic nanotubes with NGF incorporation enabled the differentiation of PC12 cells into neurons exhibiting growth cones and neurite outgrowth. Microscope observations show that filopodia extending from neuron growth cones were in close proximity to the NGF-incorporated magnetic nanotubes, at times appearing to extend towards or into them. These results show that magnetic nanotubes can be used as a delivery vehicle for NGF and thus may be exploited in attempts to treat neurodegenerative disorders such as Parkinson's disease with neurotrophins. Further neurite outgrowth can be controlled by manipulating magnetic nanotubes with external magnetic fields, thus helping in directed regeneration.

  9. Synthesis, characteristics and sonocatalytic activities of calcined γ-Fe2O3 and TiO2 nanotubes/γ-Fe2O3 magnetic catalysts in the degradation of Orange G.

    PubMed

    Pang, Yean Ling; Lim, Steven; Ong, Hwai Chyuan; Chong, Wen Tong

    2016-03-01

    In this work, γ-Fe2O3 and TiO2 NTs/γ-Fe2O3 composites with good magnetism and sonocatalytic activity were prepared by a facile polyol method and utilize the principle of isoelectric point method, respectively. The structural and magnetic features of the prepared calcined γ-Fe2O3 and composite catalysts were investigated by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), surface analysis, UV-Vis diffuse reflectance spectra (UV-Vis DRS), vibrating sample magnetometry (VSM) and zeta potential analysis. The effects of calcination temperature on γ-Fe2O3 phase variation, physical properties and sonocatalytic properties were investigated. The porosity, specific surface area, band gap energy and sonocatalytic activity of γ-Fe2O3 were gradually decreased with calcination temperature increased. TiO2 NTs/γ-Fe2O3 with appropriate composition and specific structural features possess synergetic effects such as efficient separation of charge carriers and hydroxyl radicals produced by heterogeneous fenton and fenton-like reactions. This enhanced the sonocatalytic activity for the degradation of Orange G under ultrasonic irradiation. The sonocatalytic reactions obeyed pseudo first-order kinetics. All these information provide insight into the design and development of high-efficiency catalyst for wastewater treatment.

  10. Phenol degradation by TiO2 photocatalysts combined with different pulsed discharge systems.

    PubMed

    Zhang, Yi; Lu, Jiani; Wang, Xiaoping; Xin, Qing; Cong, Yanqing; Wang, Qi; Li, Chunjuan

    2013-11-01

    Films of TiO2 nanotubes distributed over the inner surface of a discharge reactor cylinder (CTD) or adhered to a stainless steel electrode surface (PTD) in a discharge reactor were compared with a single-discharge (SD) system to investigate their efficiencies in phenol degradation. Morphology studies indicated that the TiO2 film was destroyed in the PTD system, but that there was no change in the CTD system after discharge. X-ray diffraction results revealed that the anatase phase of the original sample was preserved in the CTD system, but that an anatase-to-rutile phase transformation occurred in the PTD system after discharge. The highest efficiencies of phenol degradation and total organic carbon (TOC) mineralization were observed in the CTD system, and there was no decrease in phenol degradation efficiency upon reuse of a TiO2 film, indicating high catalysis activity and stability of the TiO2 photocatalysts in the combined treatment. TiO2 photocatalysts favored the formation of hydrogen peroxide and disfavored the formation of ozone. A greater degree of oxidation of intermediates and higher energy efficiency in phenol oxidation were observed with the TiO2-plasma systems, especially in the CTD system, compared to those with the SD system.

  11. Composite WO3/TiO2 nanostructures for high electrochromic activity

    DOE PAGESBeta

    Reyes-Gil, Karla R.; Stephens, Zachary D.; Stavila, Vitalie; Robinson, David B.

    2015-01-06

    A composite material consisting of TiO2 nanotubes (NT) with WO3 electrodeposited on its surface has been fabricated, detached from its Ti substrate, and attached to a fluorine-doped tin oxide (FTO) film on glass for application to electrochromic (EC) reactions. Several adhesion layers were tested, finding that a paste of TiO2 made from commercially available TiO2 nanoparticles creates an interface for the TiO2 NT film to attach to the FTO glass, which is conductive and does not cause solution-phase ions in an electrolyte to bind irreversibly with the material. The effect of NT length and WO3 concentration on the EC performancemore » were studied. As a result, the composite WO3/TiO2 nanostructures showed higher ion storage capacity, better stability, enhanced EC contrast, and longer memory time compared with the pure WO3 and TiO2 materials« less

  12. Composite WO3/TiO2 nanostructures for high electrochromic activity.

    SciTech Connect

    Reyes, Karla Rosa; Stephens, Zachary Dan.; Robinson, David B.

    2013-05-01

    A composite material consisting of TiO2 nanotubes (NTs) with WO3 electrodeposited homogeneously on its surface has been fabricated, detached from its substrate, and attached to a fluorine-doped tin oxide film on glass for application to electrochromic (EC) reactions. A paste of TiO2 made from commercially available TiO2 nanoparticles creates an interface for the TiO2 NT film to attach to the FTO glass, which is conductive and does not cause solution-phase ions in an electrolyte to bind irreversibly with the material. The effect of NT length on the current density and the EC contrast of the material were studied. The EC redox reaction seen in this material is diffusion- limited, having relatively fast reaction rates at the electrode surface. The composite WO3/TiO2 nanostructures showed higher ion storage capacity, better stability, enhanced EC contrast and longer memory time compared with the pure WO3 and TiO2.

  13. A Designed TiO2 /Carbon Nanocomposite as a High-Efficiency Lithium-Ion Battery Anode and Photocatalyst.

    PubMed

    Peng, Liang; Zhang, Huijuan; Bai, Yuanjuan; Feng, Yangyang; Wang, Yu

    2015-10-12

    Herein, a peapod-like TiO2 /carbon nanocomposite has successfully been synthesized by a rational method for the first time. The novel nanostructure exhibits a distinct feature of TiO2 nanoparticles encapsulated inside and the carbon fiber coating outside. In the synthetic process, H2 Ti3 O7 nanotubes serve as precursors and templates, and glucose molecules act as the green carbon source. With the alliciency of hydrogen bonding between H2 Ti3 O7 and glucose, a thin polymer layer is hydrothermally assembled and subsequently converted into carbon fibers through calcinations under an inert atmosphere. Meanwhile, the precursors of H2 Ti3 O7 nanotubes are transformed into the TiO2 nanoparticles encapsulated in carbon fibers. The achieved unique nanocomposites can be used as excellent anode materials in lithium-ion batteries (LIBs) and photocatalytic reagents in the degradation of rhodamine B. Due to the synergistic effect derived from TiO2 nanoparticles and carbon fibers, the obtained peapod-like TiO2 /carbon cannot only deliver a high specific capacity of 160 mAh g(-1) over 500 cycles in LIBs, but also perform a much faster photodegradation rate than bare TiO2 and P25. Furthermore, owing to the low cost, environmental friendliness as well as abundant source, this novel TiO2 /carbon nanocomposite will have a great potential to be extended to other application fields, such as specific catalysis, gas sensing, and photovoltaics.

  14. Enhanced Photovoltaic Performance with Carbon Nanotubes Incorporating into Hole Transport Materials for Perovskite Solar Cells

    NASA Astrophysics Data System (ADS)

    Wang, Junxia; Li, Jingling; Xu, Xueqing; Xu, Gang; Shen, Honglie

    2016-10-01

    In an attempt to further enhance the photovoltaic performance of perovskite solar cells (PSCs) fabricated by spray deposition under ambient conditions, carbon nanotubes (CNTs) are introduced for incorporation into hole transport materials (HTM). The effect of CNT category and length on the efficiency of the perovskite solar cell for incorporation into HTM is investigated. The enhanced photovoltaic performance is achieved in multi-walled carbon nanotubes (MWCNTs) with the shortest length. The efficiency of acid-treated MWCNT-based cells is improved compared to that of purified MWCNTs due to the better dispersibility and the π-π interaction between the -COOH group and spiro-OMeTAD. As the volume ratio of the spiro-OMeTAD and spiro/MWCNTs mixture is 2:2 or 3:1, the highest power conversion efficiency (PCE) of PSCs containing MWCNTs reaches 8.7% with the enhanced short-circuit current density ( J sc) and open-circuit voltage ( V oc).

  15. Enhanced Photovoltaic Performance with Carbon Nanotubes Incorporating into Hole Transport Materials for Perovskite Solar Cells

    NASA Astrophysics Data System (ADS)

    Wang, Junxia; Li, Jingling; Xu, Xueqing; Xu, Gang; Shen, Honglie

    2016-06-01

    In an attempt to further enhance the photovoltaic performance of perovskite solar cells (PSCs) fabricated by spray deposition under ambient conditions, carbon nanotubes (CNTs) are introduced for incorporation into hole transport materials (HTM). The effect of CNT category and length on the efficiency of the perovskite solar cell for incorporation into HTM is investigated. The enhanced photovoltaic performance is achieved in multi-walled carbon nanotubes (MWCNTs) with the shortest length. The efficiency of acid-treated MWCNT-based cells is improved compared to that of purified MWCNTs due to the better dispersibility and the π-π interaction between the -COOH group and spiro-OMeTAD. As the volume ratio of the spiro-OMeTAD and spiro/MWCNTs mixture is 2:2 or 3:1, the highest power conversion efficiency (PCE) of PSCs containing MWCNTs reaches 8.7% with the enhanced short-circuit current density (J sc) and open-circuit voltage (V oc).

  16. Defect generation, d- d transition, and band gap reduction in Cu-doped TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Choudhury, Biswajit; Dey, Munmun; Choudhury, Amarjyoti

    2013-04-01

    TiO2 doped with Cu2+ initiates the formation of brookite phase along with anatase. Doping of Cu2+ introduces structural defects into TiO2. The direct evidence is the low intense and broad diffraction peaks. Raman peaks of doped TiO2 are also broad and are blueshifted. Pure TiO2 exhibits an absorption in the UV region, the position of which is shifted towards the visible region on incorporation of Cu into it. The visible absorption peaks arise due to the d- d transition of Cu2+ in the crystalline environment of TiO2. Incorporation of Cu2+ distorts the local structure of TiO2, resulting in the loss of octahedral symmetry surrounding Cu2+. The Jahn-Teller distortion splits the 2 E g and 2 T 2g state of Cu2+ into several d states. Interaction of light excites the electron from ground to several of the excited states and gives the visible absorption peaks in the framework of TiO2. These Cu2+ d states and oxygen defects create band states, thereby favoring electronic transition to these levels and resulting in lowering of band gap of TiO2. A direct confirmation is the increase in the magnitude of Urbach energy with the reduction in the band gap of doped TiO2.

  17. Performance Enhancement of 3-Mercaptopropionic Acid-Capped CdSe Quantum-Dot Sensitized Solar Cells Incorporating Single-Walled Carbon Nanotubes.

    PubMed

    Yang, Jonghee; Park, Taehee; Lee, Jongtaek; Lee, Junyoung; Shin, Hokyeong; Yi, Whikun

    2016-03-01

    We fabricated a series of linker-assisted quantum-dot-sensitized solar cells based on the ex situ self-assembly of CdSe quantum dots (QDs) onto TiO2 electrode using sulfide/polysulfide (S(2-)/Sn(2-)) as an electrolyte and Au cathode. Our cell were combined with single-walled carbon nanotubes (SWNTs) by two techniques; One was mixing SWNTs with TiO2 electrode and the other was spraying SWNTs onto Au electrode. Absorption spectra were used to confirm the adsorption of QDs onto TiO2 electrode. Cell performance was measured on samples containing and not-containing SWNTs. Samples mixing SWNTs with TiO2 showed higher cell efficiency, on the while sample spraying SWNTs onto Au electrode showed lower efficiency compared with pristine sample (not-containing SWNTs). Electrochemical impedance spectroscopy analysis suggested that SWNTs can act as either barriers or excellent carrier transfers according their position and mixing method.

  18. Photodegradation of phenanthrene by N-doped TiO2 photocatalyst.

    PubMed

    Sirisaksoontorn, Weekit; Thachepan, Surachai; Songsasen, Apisit

    2009-07-15

    The photodegradation of phenanthrene has been catalyzed by nanostructures of TiO2 doped with nitrogen, N-doped TiO2. The N-doped TiO2 was prepared from the sol-gel reaction of Titanium(IV) bis(ethyl acetoacetato)diisopropoxide with 25% ammonia solution. The N-doped TiO2 was calcined at various temperatures from 300 to 700 degrees C. X-ray diffraction (XRD) results showed that N-doped TiO2 remained amorphous at 300 degrees C but anatase-to-rutile transformation started at 400 degrees C and was complete at 700 degrees C. The average particle size calculated from Scherrer's equation was in the range of 9-51 nm with surface area (S(BET)) of 253.7-4.8 m2/g. X-ray photoelectron spectroscopy (XPS) results confirmed the incorporation of nitrogen atoms (Ti-N bond) in the N-doped catalyst. Moreover, the percentage of nitrogen determined by Elemental analysis was 0.236% of N-doped calcined at 400 degrees C. UV-Vis reflection spectra indicated that N-doped TiO2 calcined at 400 degrees C shifted to the higher absorption edge in the range of visible light. N-doped TiO2 calcined at 400 degrees C successfully catalyzed the photodegradation of phenanthrene (80% conversion) whereas N-doped TiO2 calcined at 500 degrees C and P25 TiO2 failed as catalysts.

  19. Molecular design of TiO2 for gigantic red shift via sublattice substitution.

    PubMed

    Shao, Guosheng; Deng, Quanrong; Wan, Lin; Guo, Meilan; Xia, Xiaohong; Gao, Yun

    2010-11-01

    The effects of 3d transition metal doping in TiO2 phases have been simulated in detail. The results of modelling indicate that Mn has the biggest potential among 3d transition metals, for the reduction of energy gap and the introduction of effective intermediate bands to allow multi-band optical absorption. On the basis of theoretical formulation, we have incorporated considerable amount of Mn in nano-crystalline TiO2 materials. Mn doped samples demonstrate significant red shift in the optical absorption edge, with a secondary absorption edge corresponding to theoretically predicted intermediate bands/states. The gigantic red shift achievable in Mn-doped TiO2 is expected to extend the useful TiO2 functionalities well beyond the UV threshold via the optical absorption of both visible and infrared photon irradiance.

  20. ZnFe2O4-TiO2 Nanoparticles within Mesoporous MCM-41

    PubMed Central

    Tang, Aidong; Deng, Yuehua; Jin, Jiao; Yang, Huaming

    2012-01-01

    A novel nanocomposite ZnFe2O4-TiO2/MCM-41 (ZTM) was synthesized by a sol-gel method and characterized through X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), N2 adsorption-desorption, Raman spectroscopy, and ultraviolet visible (UV-vis) spectrophotometry. The results confirmed the incorporation of ZnFe2O4-TiO2 nanoparticles inside the pores of the mesoporous MCM-41 host without destroying its integrity. ZnFe2O4 nanoparticles can inhibit the transformation of anatase into rutile phase of TiO2. Incorporation of ZnFe2O4-TiO2 within MCM-41 avoided the agglomeration of nanoparticles and reduced the band gap energy of TiO2 to enhance its visible light photocatalytic activity. UV-vis absorption edges of ZTM nanocomposites redshifted with the increase of Zn/Ti molar ratio. The nanocomposite approach could be a potential choice for enhancing the photoactivity of TiO2, indicating an interesting application in the photodegradation and photoelectric fields. PMID:22919325

  1. ZnFe2O4-TiO2 nanoparticles within mesoporous MCM-41.

    PubMed

    Tang, Aidong; Deng, Yuehua; Jin, Jiao; Yang, Huaming

    2012-01-01

    A novel nanocomposite ZnFe(2)O(4)-TiO(2)/MCM-41 (ZTM) was synthesized by a sol-gel method and characterized through X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), N(2) adsorption-desorption, Raman spectroscopy, and ultraviolet visible (UV-vis) spectrophotometry. The results confirmed the incorporation of ZnFe(2)O(4)-TiO(2) nanoparticles inside the pores of the mesoporous MCM-41 host without destroying its integrity. ZnFe(2)O(4) nanoparticles can inhibit the transformation of anatase into rutile phase of TiO(2). Incorporation of ZnFe(2)O(4)-TiO(2) within MCM-41 avoided the agglomeration of nanoparticles and reduced the band gap energy of TiO(2) to enhance its visible light photocatalytic activity. UV-vis absorption edges of ZTM nanocomposites redshifted with the increase of Zn/Ti molar ratio. The nanocomposite approach could be a potential choice for enhancing the photoactivity of TiO(2), indicating an interesting application in the photodegradation and photoelectric fields.

  2. The effect of polyaniline on TiO2 nanoparticles as anode materials for lithium ion batteries.

    PubMed

    Zheng, Haitao; Ncube, Ntombizodwa M; Raju, Kumar; Mphahlele, Nonhlanhla; Mathe, Mkhulu

    2016-01-01

    Polyaniline (PANI) additives have been shown to have a significant effect on titanium dioxide (TiO2) nanoparticles as lithium ion battery anode materials. TiO2/PANI composites were prepared using a solid coating method with different ratios of PANI and then characterized using XRD and SEM. These composites have shown increased reversible capacity compared with pure TiO2. At the current rate of 20 and 200 mAg(-1), maximum capacities were also found on 15 % PANI incorporated TiO2 composite with 281 mAh g(-1) and 168.2 mAh g(-1), respectively, and 230 and 99.6 mAh g(-1) were obtained in the case of pure TiO2. Among all the composite materials, 10 % PANI incorporated TiO2 composite exhibited the highest reversible capacity with cycle stability after 100 cycles at the current rate of 200 mAg(-1), suggestive that the optimal ratio is 10 % PANI of TiO2/polyaniline. The cycle stability showed swift fade when the ratio of PANI in the composites exceeded 10 % though the highest initial capacity was achieved on 15 % PANI in the composites. These results suggest that PANI has effectively enhanced the reversible capacity of commercial TiO2, and may be a promising polymer matrix materials for lithium ion batteries. PMID:27330896

  3. The effect of polyaniline on TiO2 nanoparticles as anode materials for lithium ion batteries.

    PubMed

    Zheng, Haitao; Ncube, Ntombizodwa M; Raju, Kumar; Mphahlele, Nonhlanhla; Mathe, Mkhulu

    2016-01-01

    Polyaniline (PANI) additives have been shown to have a significant effect on titanium dioxide (TiO2) nanoparticles as lithium ion battery anode materials. TiO2/PANI composites were prepared using a solid coating method with different ratios of PANI and then characterized using XRD and SEM. These composites have shown increased reversible capacity compared with pure TiO2. At the current rate of 20 and 200 mAg(-1), maximum capacities were also found on 15 % PANI incorporated TiO2 composite with 281 mAh g(-1) and 168.2 mAh g(-1), respectively, and 230 and 99.6 mAh g(-1) were obtained in the case of pure TiO2. Among all the composite materials, 10 % PANI incorporated TiO2 composite exhibited the highest reversible capacity with cycle stability after 100 cycles at the current rate of 200 mAg(-1), suggestive that the optimal ratio is 10 % PANI of TiO2/polyaniline. The cycle stability showed swift fade when the ratio of PANI in the composites exceeded 10 % though the highest initial capacity was achieved on 15 % PANI in the composites. These results suggest that PANI has effectively enhanced the reversible capacity of commercial TiO2, and may be a promising polymer matrix materials for lithium ion batteries.

  4. SALDI-TOF-MS analyses of small molecules (citric acid, dexasone, vitamins E and A) using TiO2 nanocrystals as substrates.

    PubMed

    Popović, Iva A; Nešić, Maja; Vranješ, Mila; Šaponjić, Zoran; Petković, Marijana

    2016-10-01

    Surface-assisted laser desorption/ionisation time-of-flight mass spectrometry (SALDI-TOF-MS) might be the method of choice for the analysis of low mass molecules (less than m/z 500). Titanium dioxide (TiO2) nanocrystals as a substrate for SALDI-TOF-MS improve the reproducibility of the signal intensities and prevent the fragmentation of some molecules upon laser irradiation, as we have previously shown. In addition, variously shaped and sized TiO2 nanocrystals/substrates for SALDI-MS could be used for quantification of small molecules, which are otherwise difficult to detect with the assistance of organic matrices. TiO2-assisted LDI-MS spectra could be acquired with excellent reproducibility and repeatability and with low detection limit. In the current study, we analysed the spectra of dexasone, citric acid, vitamin E and vitamin A acquired with TiO2 nanocrystals of various shapes and dimensions, i.e. the colloidal TiO2 nanoparticles (TiO2 NPs), TiO2 prolate nanospheroids (TiO2 PNSs) and TiO2 nanotubes (TiO2 NTs). Various shapes and dimensions of substrates were used since these factors determine desorption and ionisation processes. The homogeneity on the target plate was compared based on signal-to-noise values of peaks of interest of analysed molecules as well as the within-day and day-to-day repeatability. In summary, the obtained results show that the applicability of individual TiO2 nanocrystals depends on the analyte. Signals which are acquired with the assistance of TiO2 PNSs have the highest sensitivity and reproducibility (the smallest standard deviation), even compared with those in the LDI mode. This implies that TiO2 PNSs could also be suitable for quantitative analyses of small molecules. PMID:27510281

  5. Facile Synthesis of Robust Free-Standing TiO2 Nanotubular Membranes for Biofiltration Applications.

    PubMed

    Schweicher, Julien; Desai, Tejal A

    2014-03-01

    Robust monodisperse nanoporous membranes have a wide range of biotechnological applications, but are often difficult or costly to fabricate. Here, a simple technique is reported to produce free-standing TiO2 nanotubular membranes with through-hole morphology. It consists in a 3-step anodization procedure carried out at room temperature on a Ti foil. The first anodization (1 h at 80 V) is used to pattern the surface of the metallic foil. Then, the second anodization (24 h at 80 V) produces the array of TiO2 nanotubes that will constitute the final membrane. A higher voltage anodization (3-5 minutes at 180 V) is finally applied to detach the TiO2 nanotubular layer from the underlying Ti foil. In order to completely remove the barrier layer that obstructs some pores of the membrane, the latter is etched 2 minutes in a buffered oxide etch solution. The overall process produces 60 μm-thick TiO2 nanotubular membranes with tube openings of 110 nm on one side and 73 nm on the other side. The through-hole morphology of these membranes has been verified by performing diffusion experiments with glucose, insulin and immunoglobulin G where in differences in diffusion rate are observed based on molecular weight. Such biocompatible TiO2 nanotubular membranes, with controlled pore size and morphology, have broad biotechnological and biomedical applications. PMID:24634542

  6. Enhancing antimicrobial activity of TiO2/Ti by torularhodin bioinspired surface modification.

    PubMed

    Ungureanu, Camelia; Dumitriu, Cristina; Popescu, Simona; Enculescu, Monica; Tofan, Vlad; Popescu, Marian; Pirvu, Cristian

    2016-02-01

    Implant-associated infections are a major cause of morbidity and mortality. This study was performed using titanium samples coated by anodization with a titanium dioxide (TiO2) shielded nanotube layer. TiO2/Ti surface was modified by simple immersion in torularhodin solution and by using a mussel-inspired method based on polydopamine as bio adhesive for torularhodin immobilization. SEM analysis revealed tubular microstructures of torularhodin and the PDA ability to function as a catchy anchor between torularhodin and TiO2 surface. Corrosion resistance was associated with TiO2 barrier oxide layer and nano-organized oxide layer and the torularhodin surface modification does not bring significant changes in resistance of the oxide layer. Our results demonstrated that the torularhodin modified TiO2/Ti surface could effectively prevent adhesion and proliferation of Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, and Pseudomonas aeruginosa. The new modified titanium surface showed good biocompatibility and well-behaved haemocompatibility. This biomaterial with enhanced antimicrobial activity holds great potential for future biomedical applications.

  7. The effects of titania nanotubes with embedded silver oxide nanoparticles on bacteria and osteoblasts.

    PubMed

    Gao, Ang; Hang, Ruiqiang; Huang, Xiaobo; Zhao, Lingzhou; Zhang, Xiangyu; Wang, Lin; Tang, Bin; Ma, Shengli; Chu, Paul K

    2014-04-01

    A versatile strategy to endow biomaterials with long-term antibacterial ability without compromising the cytocompatibility is highly desirable to combat biomaterial related infection. TiO2 nanotube (NT) arrays can significantly enhance the functions of many cell types including osteoblasts thus having promising applications in orthopedics, orthodontics, as well as other biomedical fields. In this study, TiO2 NT arrays with Ag2O nanoparticle embedded in the nanotube wall (NT-Ag2O arrays) are prepared on titanium (Ti) by TiAg magnetron sputtering and anodization. Well-defined NT arrays containing Ag concentrations in a wide range from 0 to 15 at % are formed. Ag incorporation has little influence on the NT diameter, but significantly decreases the tube length. Crystallized Ag2O nanoparticles with diameters ranging from 5 nm to 20 nm are embedded in the amorphous TiO2 nanotube wall and this unique structure leads to controlled release of Ag(+) that generates adequate antibacterial activity without showing cytotoxicity. The NT-Ag2O arrays can effectively kill Escherichia coli and Staphylococcus aureus even after immersion for 28 days, demonstrating the long lasting antibacterial ability. Furthermore, the NT-Ag2O arrays have no appreciable influence on the osteoblast viability, proliferation, and differentiation compared to the Ag free TiO2 NT arrays. Ag incorporation even shows some favorable effects on promoting cell spreading. The technique reported here is a versatile approach to develop biomedical coatings with different functions.

  8. Conducting polymer composite film incorporated with aligned carbon nanotubes for transparent, flexible and efficient supercapacitor

    PubMed Central

    Lin, Huijuan; Li, Li; Ren, Jing; Cai, Zhenbo; Qiu, Longbin; Yang, Zhibin; Peng, Huisheng

    2013-01-01

    Polyaniline composite films incorporated with aligned multi-walled carbon nanotubes (MWCNTs) are synthesized through an easy electrodeposition process. These robust and electrically conductive films are found to function as effective electrodes to fabricate transparent and flexible supercapacitors with a maximum specific capacitance of 233 F/g at a current density of 1 A/g. It is 36 times of bare MWCNT sheet, 23 times of pure polyaniline and 3 times of randomly dispersed MWCNT/polyaniline film under the same conditions. The novel supercapacitors also show a high cyclic stability. PMID:23443325

  9. Formation of hydroxyl radicals and kinetic study of 2-chlorophenol photocatalytic oxidation using C-doped TiO2, N-doped TiO2, and C,N Co-doped TiO2 under visible light.

    PubMed

    Ananpattarachai, Jirapat; Seraphin, Supapan; Kajitvichyanukul, Puangrat

    2016-02-01

    This work reports on synthesis, characterization, adsorption ability, formation rate of hydroxyl radicals (OH(•)), photocatalytic oxidation kinetics, and mineralization ability of C-doped titanium dioxide (TiO2), N-doped TiO2, and C,N co-doped TiO2 prepared by the sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy were used to analyze the titania. The rate of formation of OH(•) for each type of titania was determined, and the OH-index was calculated. The kinetics of as-synthesized TiO2 catalysts in photocatalytic oxidation of 2-chlorophenol (2-CP) under visible light irradiation were evaluated. Results revealed that nitrogen was incorporated into the lattice of titania with the structure of O-Ti-N linkages in N-doped TiO2 and C,N co-doped TiO2. Carbon was joined to the Ti-O-C bond in the C-doped TiO2 and C,N co-doped TiO2. The 2-CP adsorption ability of C,N co-doped TiO2 and C-doped TiO2 originated from a layer composed of a complex carbonaceous mixture at the surface of TiO2. C,N co-doped TiO2 had highest formation rate of OH(•) and photocatalytic activity due to a synergistic effect of carbon and nitrogen co-doping. The order of photocatalytic activity per unit surface area was the same as that of the formation rate of OH(•) unit surface area in the following order: C,N co-doped TiO2 > C-doped TiO2 > N-doped TiO2 > undoped TiO2.

  10. Preparation and characterization of a novel PVDF ultrafiltration membrane by blending with TiO2-HNTs nanocomposites

    NASA Astrophysics Data System (ADS)

    Zeng, Guangyong; He, Yi; Yu, Zongxue; Zhan, Yingqing; Ma, Lan; Zhang, Lei

    2016-05-01

    Novel polyvinylidene fluoride (PVDF) ultrafiltration membranes were prepared by blending with different contents of titanium dioxide-halloysite nanotubes (TiO2-HNTs) composites into the PVDF matrix. The effects of TiO2-HNTs content on the membrane performances, such as hydrophilicity, rejection ratio and antifouling properties were investigated in detail. X-ray diffraction (XRD), thermo-gravimetric analyzer (TGA) and scanning electron microscope (SEM) analyses showed that TiO2 was loaded on the surface of HNTs successfully and homogeneously by sol-gel method. The morphologies and microstructure of the membranes were characterized by SEM and atomic force microscopy (AFM). The contact angle (CA) tests indicated that the hydrophilicity of membranes was significantly increased with the addition of TiO2-HNTs. The pure water flux of 3%TiO2-HNTs/PVDF was increased by 264.8% and 35.6%, respectively, compared with pure PVDF membrane and 3%TiO2/PVDF membrane, although the rejection of bovine serum albumin (BSA) was slightly decreased. More importantly, TiO2-HNTs/PVDF membrane exhibited an excellent anti-fouling performance, which was attributed to the hydrophobic contaminants being resisted by hydrophilic nanoparticles. It can be expected that this work may provide some references to solve the dispersion of nanoparticle in the membrane and improve the anti-fouling performance of membrane in the field of wastewater treatment.

  11. Microwave-assisted self-doping of TiO2 photonic crystals for efficient photoelectrochemical water splitting.

    PubMed

    Zhang, Zhonghai; Yang, Xiulin; Hedhili, Mohamed Nejib; Ahmed, Elaf; Shi, Le; Wang, Peng

    2014-01-01

    In this article, we report that the combination of microwave heating and ethylene glycol, a mild reducing agent, can induce Ti(3+) self-doping in TiO2. A hierarchical TiO2 nanotube array with the top layer serving as TiO2 photonic crystals (TiO2 NTPCs) was selected as the base photoelectrode. The self-doped TiO2 NTPCs demonstrated a 10-fold increase in visible-light photocurrent density compared to the nondoped one, and the optimized saturation photocurrent density under simulated AM 1.5G illumination was identified to be 2.5 mA cm(-2) at 1.23 V versus reversible hydrogen electrode, which is comparable to the highest values ever reported for TiO2-based photoelectrodes. The significant enhancement of photoelectrochemical performance can be ascribed to the rational coupling of morphological and electronic features of the self-doped TiO2 NTPCs: (1) the periodically morphological structure of the photonic crystal layer traps broadband visible light, (2) the electronic interband state induced from self-doping of Ti(3+) can be excited in the visible-light region, and (3) the captured light by the photonic crystal layer is absorbed by the self-doped interbands.

  12. Preparation and Characterisation of Hydroxyapatite Coatings on Nanotubular TiO2 Surface Obtained by Sol-Gel Process.

    PubMed

    Shin, Jin-Ho; Kim, Jung-Hwa; Koh, Jeong-Tae; Lim, Hyun-Pil; Oh, Gye-Jeong; Lee, Seok-Woo; Lee, Kwang-Min; Yun, Kwi-Dug; Park, Sang-Won

    2015-08-01

    Hydroxyapatite (HA) coating on titanium dioxide (TiO2) nanotubular surface has been developed to complement the defects of both TiO2 and HA. A sol-gel processing technique was used to coat HA on TiO2 nanotubular surface. All the titanium discs were blasted with resorbable blast media (RBM). RBM-blasted Ti surface, anodized Ti surface, and sol-gel HA coating on the anodized Ti surface were prepared. The characteristics of samples were observed using scanning electron microscopy and X-ray photoemission spectroscopy. Biologic responses were evaluated with human osteosarcoma MG63 cells in vitro. The top of the TiO2 nanotubes was not completely covered by HA particles when the coating time was less than 60 sec. It was demonstrated the sol-gel derived HA film was well-crystallized and this enhanced biologic responses in early stage cell response.

  13. Bifunctional ultraviolet/ultrasound responsive composite TiO2/polyelectrolyte microcapsules.

    PubMed

    Gao, Hui; Wen, Dongsheng; Tarakina, Nadezda V; Liang, Jierong; Bushby, Andy J; Sukhorukov, Gleb B

    2016-03-01

    Designing and fabricating multifunctional microcapsules are of considerable interest in both academic and industrial research aspects. This work reports an innovative approach to fabricate composite capsules with high UV and ultrasound responsive functionalities that can be used as external triggers for controlled release, yet with enhanced mechanical strength that can make them survive in a harsh environment. Needle-like TiO2 nanoparticles (NPs) were produced in situ into layer-by-layer (LbL) polyelectrolyte (PE) shells through the hydrolysis of titanium butoxide (TIBO). These rigid TiO2 NPs yielded the formed capsules with excellent mechanical strength, showing a free standing structure. A possible mechanism is proposed for the special morphology formation of the TiO2 NPs and their reinforcing effects. Synergistically, their response to UV and ultrasound was visualized via SEM, with the results showing an irreversible shell rapture upon exposure to either UV or ultrasound irradiation. As expected, the release studies revealed that the dextran release from the TiO2/PE capsules was both UV-dependent and ultrasound-dependent. Besides, the biocompatibility of the capsules with the incorporation of amorphous TiO2 NPs was confirmed by an MTT assay experiment. All these pieces of evidence suggested a considerable potential medicinal application of TiO2/PE capsules for controlled drug delivery. PMID:26878702

  14. TiO(2)/TiSi(2) heterostructures for high-efficiency photoelectrochemical H(2)O splitting.

    PubMed

    Lin, Yongjing; Zhou, Sa; Liu, Xiaohua; Sheehan, Stafford; Wang, Dunwei

    2009-03-01

    A TiO(2)/TiSi(2) complex heteronanostructure was synthesized to improve the efficiencies of TiO(2) in photosplitting H(2)O. Photoactive TiO(2) served to convert incident photons into separated charges, and the supporting TiSi(2) nanonet acted as an efficient conductor to transport separated charges. The structural complexity of TiSi(2) also provided a framework of high surface area to enhance photoabsorption. 16.7% peak conversion efficiency was obtained when measured under monochromic UV illuminations. The TiO(2) growth was further explored to extend the absorption to the visible range by incorporating W into TiO(2), and 0.83% efficiency was measured under simulated solar lights.

  15. Porous TiO2 Assembled from Monodispersed Nanoparticles

    NASA Astrophysics Data System (ADS)

    Liu, Xu; Duan, Weijie; Chen, Yan; Jiao, Shihui; Zhao, Yue; Kang, Yutang; Li, Lu; Fang, Zhenxing; Xu, Wei; Pang, Guangsheng

    2016-03-01

    Porous TiO2 were assembled by evaporating or refluxing TiO2 colloid, which was obtained by dispersing the TiO2 nanoparticles with a crystallite size (d XRD) of 3.2 nm into water or ethanol without any additives. Porous transparent bulk TiO2 was obtained by evaporating the TiO2-C2H5OH colloid at room temperature for 2 weeks, while porous TiO2 nanospheres were assembled by refluxing the TiO2-H2O colloid at 80 °C for 36 h. Both of the porous TiO2 architectures were pore-size-adjustable depending on the further treating temperature. Porous TiO2 nanospheres exhibited enhanced photocatalysis activity compared to the nanoparticles.

  16. Characterization and improved solar light activity of vanadium doped TiO2/diatomite hybrid catalysts.

    PubMed

    Wang, Bin; Zhang, Guangxin; Leng, Xue; Sun, Zhiming; Zheng, Shuilin

    2015-03-21

    V-doped TiO2/diatomite composite photocatalysts with different vanadium concentrations were synthesized by a modified sol-gel method. The diatomite was responsible for the well dispersion of TiO2 nanoparticles on the matrix and consequently inhibited the agglomeration. V-TiO2/diatomite hybrids showed red shift in TiO2 absorption edge with enhanced absorption intensity. Most importantly, the dopant energy levels were formed in the TiO2 bandgap due to V(4+) ions substituted to Ti(4+) sites. The 0.5% V-TiO2/diatomite photocatalyst displayed narrower bandgap (2.95 eV) compared to undoped sample (3.13 eV) and other doped samples (3.05 eV) with higher doping concentration. The photocatalytic activities of V doped TiO2/diatomite samples for the degradation of Rhodamine B under stimulated solar light illumination were significantly improved compared with the undoped sample. In our case, V(4+) ions incorporated in TiO2 lattice were responsible for increased visible-light absorption and electron transfer to oxygen molecules adsorbed on the surface of TiO2 to produce superoxide radicals ˙O2(-), while V(5+) species presented on the surface of TiO2 particles in the form of V2O5 contributed to e(-)-h(+) separation. In addition, due to the combination of diatomite as support, this hybrid photocatalyst could be separated from solution quickly by natural settlement and exhibited good reusability.

  17. Characterization and improved solar light activity of vanadium doped TiO2/diatomite hybrid catalysts.

    PubMed

    Wang, Bin; Zhang, Guangxin; Leng, Xue; Sun, Zhiming; Zheng, Shuilin

    2015-03-21

    V-doped TiO2/diatomite composite photocatalysts with different vanadium concentrations were synthesized by a modified sol-gel method. The diatomite was responsible for the well dispersion of TiO2 nanoparticles on the matrix and consequently inhibited the agglomeration. V-TiO2/diatomite hybrids showed red shift in TiO2 absorption edge with enhanced absorption intensity. Most importantly, the dopant energy levels were formed in the TiO2 bandgap due to V(4+) ions substituted to Ti(4+) sites. The 0.5% V-TiO2/diatomite photocatalyst displayed narrower bandgap (2.95 eV) compared to undoped sample (3.13 eV) and other doped samples (3.05 eV) with higher doping concentration. The photocatalytic activities of V doped TiO2/diatomite samples for the degradation of Rhodamine B under stimulated solar light illumination were significantly improved compared with the undoped sample. In our case, V(4+) ions incorporated in TiO2 lattice were responsible for increased visible-light absorption and electron transfer to oxygen molecules adsorbed on the surface of TiO2 to produce superoxide radicals ˙O2(-), while V(5+) species presented on the surface of TiO2 particles in the form of V2O5 contributed to e(-)-h(+) separation. In addition, due to the combination of diatomite as support, this hybrid photocatalyst could be separated from solution quickly by natural settlement and exhibited good reusability. PMID:25497036

  18. Instability of Hydrogenated TiO2

    SciTech Connect

    Nandasiri, Manjula I.; Shutthanandan, V.; Manandhar, Sandeep; Schwarz, Ashleigh M.; Oxenford, Lucas S.; Kennedy, John V.; Thevuthasan, Suntharampillai; Henderson, Michael A.

    2015-11-06

    Hydrogenated TiO2 (H-TiO2) is toted as a viable visible light photocatalyst. We report a systematic study on the thermal stability of H-implanted TiO2 using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA). Protons (40 keV) implanted at a ~2 atom % level within a ~120 nm wide profile of rutile TiO2(110) were situated ~300 nm below the surface. NRA revealed that this H-profile broadened preferentially toward the surface after annealing at 373 K, dissipated out of the crystal into vacuum at 473 K, and was absent within the beam sampling depth (~800 nm) at 523 K. Photoemission showed that the surface was reduced in concert with these changes. Similar anneals had no effect on pristine TiO2(110). The facile bulk diffusivity of H in rutile, as well as its activity toward interfacial reduction, significantly limits the utilization of H-TiO2 as a photocatalyst. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. The research was performed using the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  19. Electrochemical behavior and effect of heat treatment on morphology, crystalline structure of self-organized TiO2 nanotube arrays on Ti-6Al-7Nb for biomedical applications.

    PubMed

    Mohan, L; Anandan, C; Rajendran, N

    2015-05-01

    In the present work, we investigate the formation of self-organized titanium oxide nanotube layers by anodic oxidation on titanium alloy Ti-6Al-7Nb in electrolyte solution containing sulfuric acid and hydrofluoric acid. The anodized surface was characterized by micro-Raman, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDS). The corrosion behavior of the treated and untreated samples was investigated through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies in simulated body fluid (Hanks' solution). The investigations show that the native oxide on the sample is replaced by self-assembled nanoarray by anodization. FESEM of samples annealed at 450 to 800 °C show tubular morphology whereas those annealed at 850 °C show collapse of nanotubes. Electrochemical impedance data of the substrate and 10 V anodized samples were fitted with a two-time constant equivalent circuit and that of anodized samples (20, 30 V) with a three-time constant equivalent circuit.

  20. a New Method to Prepare the Novel Anatase TiO2

    NASA Astrophysics Data System (ADS)

    Cui, Guanjun; Xu, Zhanxia; Wang, Yan; Zhang, Min; Yang, Jianjun

    In this paper, a kind of novel anatase TiO2 nanoparticle with single-electron-trapped oxygen vacancies was prepared by hydrothermal treated nanotube titanic acid. The morphology, structure, and properties of the products were characterized by transmission electron microscope, X-ray diffraction, electron spin resonance, and photoluminescence. Photocatalytic decolorization of the Methylene Blue solution was carried out in the visible light region and showed a high photocatalytic activity.

  1. TiO2 nanoparticles doped SiO2 films with ordered mesopore channels: a catalytic nanoreactor.

    PubMed

    Saha, Jony; Mitra, Anuradha; Dandapat, Anirban; De, Goutam

    2014-04-01

    Titanium dioxide (TiO2) incorporated ordered 2D hexagonal mesoporous silica (SiO2) films on a glass substrate were fabricated for use as a catalytic nanoreactor. Films were prepared using a tetraethyl orthosilicate (TEOS) derived SiO2 sol and a commercially available dispersion of TiO2 nanoparticles (NPs) in the presence of pluronic P123 as the structure directing agent. The effect of TiO2 doping (4-10 mol% with respect to the equivalent SiO2) into the ordered mesoporous SiO2 matrix was thoroughly investigated. The undoped SiO2 film showed a mesostructural transformation after heat-treatment at 350 °C whereas incorporation of TiO2 restricted such a transformation. Among all the TiO2 incorporated films, TEM showed that the 7 equivalent mol% TiO2 doped SiO2 film (ST-7) had an optimal composition which could retain the more organized 2D hexagonal (space group p6mm)-like mesostructures after heat-treatment. The catalytic activities of the TiO2 doped (4-10 mol%) films were investigated for the reduction of toxic KMnO4 in an aqueous medium. ST-7 film showed the maximum catalytic activity, as well as reusability. A TEM study on the resultant solution after KMnO4 reduction revealed the formation of MnO2 nanowires. It was understood that the embedded TiO2 NPs bonded SiO2 matrix increased the surface hydroxyl groups of the composite films resulting in the generation of acidic sites. The catalytic process can be explained by this enhanced surface acidity. The mesoporous channel of the ST-7 films with TiO2 doping can be used as a nanoreactor to form extremely thin MnO2 nanowires.

  2. Green synthesis of polymer monoliths incorporated with carbon nanotubes in room temperature ionic liquid and deep eutectic solvents.

    PubMed

    Zhang, Li-Shun; Gao, Shu-Ping; Huang, Yan-Ping; Liu, Zhao-Sheng

    2016-07-01

    In this work, an efficient method to prepare polymer monoliths with incorporated carbon nanotubes in a mixture of room temperature ionic liquid and deep eutectic solvents was developed. With assistance of the binary green solvent, 1-butyl-3-methylimidazolium tetrafluoroborate and choline chloride/ethylene glycol, single-walled carbon nanotubes were dispersed successfully in pre-polymerization mixture without need of oxidative cutting of carbon nanotubes, which may allow depletion of the emission of volatile organic compounds into environment. The novel single-walled carbon nanotubes monolith was evaluated by capillary electrochromatography. Compared with the monolith made without single-walled carbon nanotubes, the monolith with the incorporation of single-walled carbon nanotubes exhibited high column efficiency (251,000plates/m) in the chromatographic separation. The morphology of the monolith can be tuned by the composition of mixture of ionic liquids and deep eutectic solvents to afford good column permeability and excellent separation ability for small molecules of alkyl phenones and alkyl benzenes. The results demonstrated that the method is a green strategy for the fabrication of multifunctional polymer monoliths. PMID:27154683

  3. Green synthesis of polymer monoliths incorporated with carbon nanotubes in room temperature ionic liquid and deep eutectic solvents.

    PubMed

    Zhang, Li-Shun; Gao, Shu-Ping; Huang, Yan-Ping; Liu, Zhao-Sheng

    2016-07-01

    In this work, an efficient method to prepare polymer monoliths with incorporated carbon nanotubes in a mixture of room temperature ionic liquid and deep eutectic solvents was developed. With assistance of the binary green solvent, 1-butyl-3-methylimidazolium tetrafluoroborate and choline chloride/ethylene glycol, single-walled carbon nanotubes were dispersed successfully in pre-polymerization mixture without need of oxidative cutting of carbon nanotubes, which may allow depletion of the emission of volatile organic compounds into environment. The novel single-walled carbon nanotubes monolith was evaluated by capillary electrochromatography. Compared with the monolith made without single-walled carbon nanotubes, the monolith with the incorporation of single-walled carbon nanotubes exhibited high column efficiency (251,000plates/m) in the chromatographic separation. The morphology of the monolith can be tuned by the composition of mixture of ionic liquids and deep eutectic solvents to afford good column permeability and excellent separation ability for small molecules of alkyl phenones and alkyl benzenes. The results demonstrated that the method is a green strategy for the fabrication of multifunctional polymer monoliths.

  4. On the preparation of TiO2-sepiolite hybrid materials for the photocatalytic degradation of TCE: influence of TiO2 distribution in the mineralization.

    PubMed

    Suárez, Silvia; Coronado, Juan M; Portela, Raquel; Martín, Juan Carlos; Yates, Malcolm; Avila, Pedro; Sánchez, Benigno

    2008-08-15

    Hybrid structured photocatalysts based on sepiolite, an adsorbent, and TiO2 were prepared by extrusion of ceramic dough and conformed as plates. The influence of the photocatalyst configuration was studied either by including TiO2 in the extrusion process (incorporated materials) or by coating the sepiolite plates with a TiO2 film (coated materials). The influence of the OH- surface concentration in the photocatalytic performance was studied by treating the ceramic plates at different temperatures. The samples were characterized by N2 adsorption-desorption, MIP, SEM, XRD, and UV-vis-NIR spectroscopy and tested in the photocatalytic degradation of trichloroethylene (TCE) as a target VOC molecule. Most of the catalysts presented high photoactivity, but considerable differences were observed when the CO2 selectivity was analyzed. The results demonstrate that there is a significant effect of the catalyst configuration on the selectivity of the process. An intimate contact between the sepiolite fibers and TiO2 particles for incorporated materials with a corncob-like structure favored the migration of nondesirable reaction products such as COCl2 and dichloroacetyl chloride (DCAC) to the adsorbent, reacting with OH- groups of the adsorbent and favoring the TCE mimeralization.

  5. Doping concentration dependence of microstructure and magnetic behaviours in Co-doped TiO2 nanorods

    PubMed Central

    2014-01-01

    Co-doped titanium dioxide (TiO2) nanorods with different doping concentrations were fabricated by a molten salt method. It is found that the morphology of TiO2 changes from nanorods to nanoparticles with increasing doping concentration. The mechanism for the structure and phase evolution is investigated in detail. Undoped TiO2 nanorods show strong ferromagnetism at room temperature, whereas incorporating of Co deteriorates the ferromagnetic ordering. X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) results demonstrate that the ferromagnetism is associated with Ti vacancy. PMID:25593558

  6. Photovoltaic Characterization and Electrochemical Impedance Spectroscopy Analysis of Dye-Sensitized Solar Cells Based on Composite TiO2-MWCNT Photoelectrodes

    NASA Astrophysics Data System (ADS)

    Parvazian, E.; Karimzadeh, F.; Enayati, M. H.

    2014-05-01

    Dye-sensitized solar cells (DSSCs) use the effect of light on dye molecules to generate electricity through a photoelectrochemical mechanism. The aim of this study is to synthesize nanostructured DSSCs based on titania-multiwalled carbon nanotube (TiO2-MWCNT) composite photoelectrodes and improve their performance and efficiency. DSSCs were fabricated based on single-layer TiO2-MWCNT photoelectrodes with various weight percentages of multiwalled carbon nanotubes and bilayer TiO2/TiO2-2%MWCNT photoelectrodes. The microstructure and thickness of the anodic layers were characterized by field-emission scanning electron microscopy and optical microscopy. Also, to compare the conversion efficiency and determine the electron behavior in the electrical equivalent circuit of these cells, photovoltaic characterization and electrochemical impedance spectroscopy (EIS) analysis were used. The DSSC based on a single-layer TiO2-2%MWCNT electrode, compared with other single-layer DSSCs in this study, had the highest conversion efficiency of 3.9% (for anodic layer thickness of 9 μm). The efficiency of the solar cell with the bilayer TiO2/TiO2-2%MWCNT photoelectrode, in comparison with the single-layer solar cell with the TiO2-2%MWCNT electrode, showed a 23% increase from 4.33% to 5.35% (for anodic layer thickness of 18 μm). EIS analysis indicated that the charge-transport resistance of the DSSC based on the bilayer photoelectrode, in comparison with the single-layer TiO2 and TiO2-2%MWCNT solar cells, was decreased by 68% and 57%, respectively.

  7. Evaluation of polymethyl methacrylate resin mechanical properties with incorporated halloysite nanotubes

    PubMed Central

    2016-01-01

    PURPOSE This study inspects the effect of incorporating halloysite nanotubes (HNTs) into polymethyl methacrylate (PMMA) resin on its flexural strength, hardness, and Young's modulus. MATERIALS AND METHODS Four groups of acrylic resin powder were prepared. One group without HNTs was used as a control group and the other three groups contained 0.3, 0.6 and 0.9 wt% HNTs. For each one, flexural strength, Young's modulus and hardness values were measured. One-way ANOVA and Tukey's test were used for comparison (P<.05). RESULTS At lower concentration (0.3 wt%) of HNT, there was a significant increase of hardness values but no significant increase in both flexural strength and Young's modulus values of PMMA resin. In contrast, at higher concentration (0.6 and 0.9 wt%), there was a significant decrease in hardness values but no significant decrease in flexural strength and Young's modulus values compared to those of the control group. CONCLUSION Addition of lower concentration of halloysite nanotubes to denture base materials could improve some of their mechanical properties. Improving the mechanical properties of acrylic resin base material could increase the patient satisfaction. PMID:27350849

  8. Size-controlled conformal nanofabrication of biotemplated three-dimensional TiO2 and ZnO nanonetworks

    PubMed Central

    Ceylan, Hakan; Ozgit-Akgun, Cagla; Erkal, Turan S.; Donmez, Inci; Garifullin, Ruslan; Tekinay, Ayse B.; Usta, Hakan; Biyikli, Necmi; Guler, Mustafa O.

    2013-01-01

    A solvent-free fabrication of TiO2 and ZnO nanonetworks is demonstrated by using supramolecular nanotemplates with high coating conformity, uniformity, and atomic scale size control. Deposition of TiO2 and ZnO on three-dimensional nanofibrous network template is accomplished. Ultrafine control over nanotube diameter allows robust and systematic evaluation of the electrochemical properties of TiO2 and ZnO nanonetworks in terms of size-function relationship. We observe hypsochromic shift in UV absorbance maxima correlated with decrease in wall thickness of the nanotubes. Photocatalytic activities of anatase TiO2 and hexagonal wurtzite ZnO nanonetworks are found to be dependent on both the wall thickness and total surface area per unit of mass. Wall thickness has effect on photoexcitation properties of both TiO2 and ZnO due to band gap energies and total surface area per unit of mass. The present work is a successful example that concentrates on nanofabrication of intact three-dimensional semiconductor nanonetworks with controlled band gap energies. PMID:23892593

  9. A Designed TiO2 /Carbon Nanocomposite as a High-Efficiency Lithium-Ion Battery Anode and Photocatalyst.

    PubMed

    Peng, Liang; Zhang, Huijuan; Bai, Yuanjuan; Feng, Yangyang; Wang, Yu

    2015-10-12

    Herein, a peapod-like TiO2 /carbon nanocomposite has successfully been synthesized by a rational method for the first time. The novel nanostructure exhibits a distinct feature of TiO2 nanoparticles encapsulated inside and the carbon fiber coating outside. In the synthetic process, H2 Ti3 O7 nanotubes serve as precursors and templates, and glucose molecules act as the green carbon source. With the alliciency of hydrogen bonding between H2 Ti3 O7 and glucose, a thin polymer layer is hydrothermally assembled and subsequently converted into carbon fibers through calcinations under an inert atmosphere. Meanwhile, the precursors of H2 Ti3 O7 nanotubes are transformed into the TiO2 nanoparticles encapsulated in carbon fibers. The achieved unique nanocomposites can be used as excellent anode materials in lithium-ion batteries (LIBs) and photocatalytic reagents in the degradation of rhodamine B. Due to the synergistic effect derived from TiO2 nanoparticles and carbon fibers, the obtained peapod-like TiO2 /carbon cannot only deliver a high specific capacity of 160 mAh g(-1) over 500 cycles in LIBs, but also perform a much faster photodegradation rate than bare TiO2 and P25. Furthermore, owing to the low cost, environmental friendliness as well as abundant source, this novel TiO2 /carbon nanocomposite will have a great potential to be extended to other application fields, such as specific catalysis, gas sensing, and photovoltaics. PMID:26310518

  10. Photocatalytic degradation of aqueous propoxur solution using TiO2 and Hbeta zeolite-supported TiO2.

    PubMed

    Mahalakshmi, M; Vishnu Priya, S; Arabindoo, Banumathi; Palanichamy, M; Murugesan, V

    2009-01-15

    Photocatalytic activity of TiO2 and zeolites supported TiO2 were investigated using propoxur as a model pollutant. Hbeta, HY and H-ZSM-5 zeolites were examined as supports for TiO2. Hbeta was chosen as the TiO2 support based on the adsorption capacity of propoxur on these zeolites (Hbeta>HY=H-ZSM-5). TiO2/Hbeta photocatalysts with different wt.% were prepared and characterized by XRD, FT-IR and BET surface area. The progress of photocatalytic degradation of aqueous propoxur solution using TiO2 (Degussa P-25) and TiO2 supported on Hbeta zeolite was monitored using TOC analyzer, HPLC and UV-vis spectrophotometer. The degradation of propoxur was systematically studied by varying the experimental parameters in order to achieve maximum degradation efficiency. The initial rate of degradation with TiO2/Hbeta was higher than with bare TiO2. TOC results revealed that TiO2 requires 600min for complete mineralization of propoxur whereas TiO2/Hbeta requires only 480min. TiO2/Hbeta showed enhanced photodegradation due to its high adsorption capacity on which the pollutant molecules are pooled closely and hence degraded effectively.

  11. Synthesis of TiO2 /CNT Composites and its Photocatalytic Activity Toward Sudan (I) Degradation.

    PubMed

    Miribangul, Amat; Ma, Xiaoli; Zeng, Chen; Zou, Huan; Wu, Yahui; Fan, Tengpeng; Su, Zhi

    2016-07-01

    Semiconductor photocatalysis has the potential for achieving sustainable energy generation and degrading organic contaminants. In TiO2 , the addition of carbonaceous nanomaterials has attracted extensive attention as a means to increase its photocatalytic activity. In this study, composites of TiO2 and carbon nanotubes (CNT) in various proportions were synthesized by the hydrothermal method. The crystalline structures, morphologies, and light absorption properties of the TiO2 /CNT photocatalysts were characterized by PXRD, TEM and UV-Vis absorption spectra. The photocatalytic efficiency of the composites was evaluated by the degradation of Sudan (I) in UV-Vis light. Introducing 0.1-0.5 wt% CNT was shown to substantially improve the photoactivity of TiO2 . The composite with 0.3 wt% CNT showed the best catalytic activity, and its reaction activation energy was calculated as 39.57 kJ mol(-1) from experimental rates. The degradation products of Sudan (I) with different irradiation durations were characterized by Fourier transform infrared spectroscopy, and a degradation reaction process was proposed.

  12. Evolution of hollow TiO2 nanostructures via the Kirkendall effect driven by cation exchange with enhanced photoelectrochemical performance.

    PubMed

    Yu, Yanhao; Yin, Xin; Kvit, Alexander; Wang, Xudong

    2014-05-14

    Hollow nanostructures are promising building blocks for electrode scaffolds and catalyst carriers in energy-related systems. In this paper, we report a discovery of hollow TiO2 nanostructure evolution in a vapor-solid deposition system. By introducing TiCl4 vapor pulses to ZnO nanowire templates, we obtained TiO2 tubular nanostructures with well-preserved dimensions and morphology. This process involved the cation exchange reaction between TiCl4 vapor and ZnO solid and the diffusion of reactants and products in their vapor or solid phases, which was likely a manifestation of the Kirkendall effect. The characteristic morphologies and the evolution phenomena of the hollow nanostructures from this vapor-solid system were in a good agreement with the Kirkendall effect discovered in solution systems. Complex hollow TiO2 nanostructures were successfully acquired by replicating various ZnO nanomorphologies, suggesting that this unique cation exchange process could also be a versatile tool for nanostructure replication in vapor-solid growth systems. The evolution of TiO2 nanotubes from ZnO NW scaffolds was seamlessly integrated with TiO2 NR branch growth and thus realized a pure TiO2-phased 3D NW architecture. Because of the significantly enlarged surface area and the trace amount of Zn left in the TiO2 crystals, such 3D TiO2 nanoforests demonstrated enhanced photoelectrochemical performance particularly under AM (air mass) 1.5G illumination, offering a new route for hierarchical functional nanomaterial assembly and application.

  13. TiO2-TiO2 composite resistive humidity sensor: ethanol crosssensitivity

    NASA Astrophysics Data System (ADS)

    Ghalamboran, Milad; Saedi, Yasin

    2016-03-01

    The fabrication method and characterization results of a TiO2-TiO2 composite bead used for humidity sensing along with its negative cross-sensitivity to ethanol vapor are reported. The bead shaped resistive sample sensors are fabricated by the drop-casting of a TiO2 slurry on two Pt wire segments. The dried bead is pre-fired at 750°C and subsequently impregnated with a Ti-based sol. The sample is ready for characterization after a thermal annealing at 600°C in air. Structurally, the bead is a composite of the micron-sized TiO2 crystallites embedded in a matrix of nanometric TiO2 particle aggregates. The performance of the beads as resistive humidity sensors is recorded at room temperature in standard humidity level chambers. Results evince the wide dynamic range of the sensors fabricated in the low relative humidity range. While the sensor conductance is not sensitive to ethanol vapor in dry air, in humid air, sensor's responses are negatively affected by the contaminant.

  14. TiO2/EVOH based reactive interlayer in Surlyn for organic device encapsulation

    NASA Astrophysics Data System (ADS)

    Kopanati, Gayathri N.; Ramamurthy, Praveen C.; Madras, Giridhar

    2016-02-01

    Barrier materials are important for improving the stability and lifetimes of organic electronic devices. A simple technique for improving the barrier properties of polymer films was considered in this work by using TiO2 nanoparticles in the interlayer to be incorporated in the polymer film. TiO2 was synthesized by the solution combustion technique, was further functionalized using stearic acid or octadecylamine to induce hydrophobicity and enhance processing of the composite interlayer. The grafting of these compounds on to TiO2 was investigated using Fourier transform infrared spectroscopy, Raman spectroscopy, elemental analysis and thermo-gravimetric analysis. The functionalized and neat TiO2 were blended with poly (vinyl alcohol-ethylene) (EVOH) and were melt compressed between Surlyn films. The resulting nanocomposite films were tested for their transparency and barrier properties using UV-visible spectroscopy and calcium degradation test, respectively. Further, the effectiveness of these barrier films in encapsulating organic devices was determined from accelerated aging tests. Therefore, the synthesized barrier films with neat and functionalized TiO2 in the interlayers proved to be effective as moisture barrier composite films.

  15. Inkjet printed highly porous TiO2 films for improved electrical properties of photoanode.

    PubMed

    Bernacka-Wojcik, I; Wojcik, P J; Aguas, H; Fortunato, E; Martins, R

    2016-03-01

    The aim of presented work is to show the improvements obtained in the properties of TiO2 films for dye sensitized solar cells fabricated by inkjet printing using an innovative methodology. We describe the development and properties of TiO2-based inks used in a lab-scale printer, testing various commercial TiO2 pastes. The porosity of the deposited inkjet printed TiO2 films is much higher than using the conventional "doctor blade" deposition technique, as the ink solvent evaporates during the droplet fly from the nozzle to the substrate due to its picoliter volume and the applied heating of a printing stage (70°C). Thanks to higher surface area, the dye sensitized solar cells incorporating inkjet printed TiO2 film gave higher efficiencies (ηmax≈3.06%) than the more compact films obtained by the "doctor blade" method (ηmax≈2.56%). Furthermore, electrochemical analysis indicates that for whole tested thickness range, the inkjet printed layers have higher effective electron diffusion length indicating their better transport properties.

  16. Self-referenced luminescence thermometry with Sm(3+) doped TiO2 nanoparticles.

    PubMed

    Dramićanin, M D; Antić, Ž; Ćulubrk, S; Ahrenkiel, S P; Nedeljković, J M

    2014-12-01

    The performance of Sm(3+) doped TiO2 nanoparticles for luminescence temperature sensing was tested over a temperature range from room to 110 °C. The Sm(3+) ions were incorporated into TiO2 nanocrystals using hydrolytic sol-gel route. Microstructural characterization of the obtained material was performed using transmission electron microscopy and x-ray diffraction measurements. Luminescence emission spectra of Sm(3+) doped TiO2 nanoparticles consists of two distinct spectral regions: the high energy region associated with the trap emission of the TiO2 host, and the low energy region with well-resolved emission peaks of the Sm(3+) ions. The ratio between Sm(3+) emission and TiO2 trap emission shows strong temperature dependence, and is tested for temperature sensing. The relative sensor sensitivity was found to be higher than 1% °C(-1) over given temperature range with the maximum value of 10.54% °C(-1) at 57.5 °C. Lifetime data derived from the Sm(3+) emission decay revealed that time-resolved measurements provide comparable quality of temperature sensing as corresponding ratiometric measurements, with a maximum relative sensitivity of 10.14% °C(-1) at 66.5 °C.

  17. Enhanced Photocatalytic Performance Using One Dimensional Ordered TiO2 Nanorods Modified by Graphene Oxide.

    PubMed

    Huang, Jinzhao; Fu, Ke; Yao, Nannan; Deng, Xiaolong; Ding, Meng; Shao, Minghui; Xu, Xijin; Wei, Mingzhi

    2016-02-01

    A new architecture of one dimensional ordered TiO2 nanorods modified by graphene oxide (GO) was assembled. The GO as the higher carrier mobility can reduce the recombination of carriers, which is more favourable for the methy orange (MO) degradation. Incorporating GO with the unblocked passageway for carrier transportation of the TiO2 nanorods can separate the transport pathway of electron and hole effectively. Furthermore, the large surface areas of TiO2 nanorods grown on the GO are beneficial to the enhancement of photocatalytic properties, and the reasonable band energy level can be obtained for the architecture, which is favorable for enhancing carrier separation and transportation. Finally, the higher transparency of the structure can enhance the light absorption. The photocatalyst grown on FTO substrates makes it easier to collect and recycle. PMID:27433607

  18. Electrochemical & osteoblast adhesion study of engineered TiO2 nanotubular surfaces on titanium alloys.

    PubMed

    Rahman, Zia Ur; Haider, Waseem; Pompa, Luis; Deen, K M

    2016-01-01

    TiO2 nanotubes were grafted on the surface of cpTi, Ti6Al4V and Ti6Al4V-ELI with the aim to provide a new podium for human pre-osteoblast cell (MC3T3) adhesion and proliferation. The surface morphology and chemistry of these alloys were examined with scanning electron microscopy and energy dispersive x-ray spectroscopy. TiO2 nanotubes were further characterized by cyclic potentiodynamic polarization tests and electrochemical impedance spectroscopy. The vertically aligned nanotubes were subjected to pre-osteoblast cell proliferation in order to better understand cell-material interaction. The study demonstrated that these cells interact differently with nanotubes of different titanium alloys. The significant acceleration in the growth rate of pre-osteoblast cell adhesion and proliferation is also witnessed. Additionally, the cytotoxicity of the leached metal ions was evaluated by using a tetrazolium-based bio-assay, MTS. Each group of data was operated for p<0.05, concluded one way ANOVA to investigate the significance difference.

  19. Enhanced simultaneous PEC eradication of bacteria and antibiotics by facilely fabricated high-activity {001} facets TiO2 mounted onto TiO2 nanotubular photoanode.

    PubMed

    Li, Guiying; Nie, Xin; Chen, Jiangyao; Wong, Po Keung; An, Taicheng; Yamashita, Hiromi; Zhao, Huijun

    2016-09-15

    Biohazards and coexisted antibiotics are two groups of emerging contaminants presented in various aquatic environments. They can pose serious threat to the ecosystem and human health. As a result, inactivation of biohazards, degradation of antibiotics, and simultaneous removal of them are highly desired. In this work, a novel photoanode with a hierarchical structured {001} facets exposed nano-size single crystals (NSC) TiO2 top layer and a perpendicularly aligned TiO2 nanotube array (NTA) bottom layer (NSC/NTA) was successfully fabricated. The morphology and facets of anatase TiO2 nanoparticles covered on the top of NTA layer could be controlled by adjusting precalcination temperature and heating rate as the pure NTA was clamped with glasses. Appropriate recalcination can timely remove surface F from {001} facets, and the photocatalytic activity of the resultant photoanode was subsequently activated. NSC/NTA photoanode fabricated under 500 °C precalcination with 20 °C min(-1) followed by 550 °C recalcination possessed highest photoelectrocatalytic efficiency to simultaneously remove bacteria and antibiotics. Results suggest that two-step calcination is necessary for fabrication of high photocatalytic activity NSC/NTA photoanode. The capability of simultaneous eradication of bacteria and antibiotics shows great potential for development of a versatile approach to effectively purify various wastewaters contaminated with complex pollutants.

  20. Enhanced simultaneous PEC eradication of bacteria and antibiotics by facilely fabricated high-activity {001} facets TiO2 mounted onto TiO2 nanotubular photoanode.

    PubMed

    Li, Guiying; Nie, Xin; Chen, Jiangyao; Wong, Po Keung; An, Taicheng; Yamashita, Hiromi; Zhao, Huijun

    2016-09-15

    Biohazards and coexisted antibiotics are two groups of emerging contaminants presented in various aquatic environments. They can pose serious threat to the ecosystem and human health. As a result, inactivation of biohazards, degradation of antibiotics, and simultaneous removal of them are highly desired. In this work, a novel photoanode with a hierarchical structured {001} facets exposed nano-size single crystals (NSC) TiO2 top layer and a perpendicularly aligned TiO2 nanotube array (NTA) bottom layer (NSC/NTA) was successfully fabricated. The morphology and facets of anatase TiO2 nanoparticles covered on the top of NTA layer could be controlled by adjusting precalcination temperature and heating rate as the pure NTA was clamped with glasses. Appropriate recalcination can timely remove surface F from {001} facets, and the photocatalytic activity of the resultant photoanode was subsequently activated. NSC/NTA photoanode fabricated under 500 °C precalcination with 20 °C min(-1) followed by 550 °C recalcination possessed highest photoelectrocatalytic efficiency to simultaneously remove bacteria and antibiotics. Results suggest that two-step calcination is necessary for fabrication of high photocatalytic activity NSC/NTA photoanode. The capability of simultaneous eradication of bacteria and antibiotics shows great potential for development of a versatile approach to effectively purify various wastewaters contaminated with complex pollutants. PMID:27314556

  1. High-surface-area mesoporous TiO2 microspheres via one-step nanoparticle self-assembly for enhanced lithium-ion storage.

    PubMed

    Wang, Hsin-Yi; Chen, Jiazang; Hy, Sunny; Yu, Linghui; Xu, Zhichuan; Liu, Bin

    2014-12-21

    Mesoporous TiO2 microspheres assembled from TiO2 nanoparticles with specific surface areas as high as 150 m(2) g(-1) were synthesized via a facile one-step solvothermal reaction of titanium isopropoxide and anhydrous acetone. Aldol condensation of acetone gradually releases structural H2O, which hydrolyzes and condenses titanium isopropoxide, forming TiO2 nanocrystals. Simultaneous growth and aggregation of TiO2 nanocrystals leads to the formation of high-surface-area TiO2 microspheres under solvothermal conditions. After a low-temperature post-synthesis calcination, carbonate could be incorporated into TiO2 as a dopant with the carbon source coming from the organic byproducts during the synthesis. Carbonate doping modifies the electronic structure of TiO2 (e.g., Fermi level, Ef), and thus influences its electrochemical properties. Solid electrolyte interface (SEI) formation, which is not common for titania, could be initiated in carbonate-doped TiO2 due to elevated Ef. After removing carbonate dopants by high-temperature calcination, the mesoporous TiO2 microspheres showed much improved performance in lithium insertion and stability at various current rates, attributed to a synergistic effect of high surface area, large pore size and good anatase crystallinity. PMID:25363569

  2. Selenium nanoparticles incorporated into titania nanotubes inhibit bacterial growth and macrophage proliferation.

    PubMed

    Liu, Wenwen; Golshan, Negar H; Deng, Xuliang; Hickey, Daniel J; Zeimer, Katherine; Li, Hongyi; Webster, Thomas J

    2016-08-25

    Since implants often fail due to infection and uncontrolled inflammatory responses, we designed an in vitro study to investigate the antibacterial and anti-inflammatory properties of titanium dioxide nanotubes (TNTs) incorporated with selenium nanoparticles (SeNPs). Selenium incorporation was achieved by the reaction of sodium selenite (Na2SeO3) with glutathione (GSH) under a vacuum in the presence of TNTs. Two types of bacteria and macrophages were cultured on the samples to determine their respective antibacterial and anti-inflammatory properties. The results showed that the TNT samples incorporating SeNPs (TNT-Se) inhibited the growth of Escherichia coli and Staphylococcus aureus compared to unmodified TNTs, albeit the SeNP concentration still needs to be optimized for maximal effect. At their maximum effect, the TNT-Se samples reduced the density of E. coli by 94.6% and of S. aureus by 89.6% compared to titanium controls. To investigate the underlying mechanism of this effect, the expression of six E. coli genes were tracked using qRT-PCR. Results indicated that SeNPs weakened E. coli membranes (ompA and ompF were down-regulated), decreased the function of adhesion-mediating proteins (csgA and csgG were progressively down-regulated with increasing SeNP content), and induced the production of damaging reactive oxygen species (ahpF was up-regulated). Moreover, TNT-Se samples inhibited the proliferation of macrophages, indicating that they can be used to control the inflammatory response and even prevent chronic inflammation, a condition that often leads to implant failure. In conclusion, we demonstrated that SeNP-TNTs display antibacterial and anti-inflammatory properties that are promising for improving the performance of titanium-based implants for numerous orthopedic and dental applications.

  3. Selenium nanoparticles incorporated into titania nanotubes inhibit bacterial growth and macrophage proliferation.

    PubMed

    Liu, Wenwen; Golshan, Negar H; Deng, Xuliang; Hickey, Daniel J; Zeimer, Katherine; Li, Hongyi; Webster, Thomas J

    2016-08-25

    Since implants often fail due to infection and uncontrolled inflammatory responses, we designed an in vitro study to investigate the antibacterial and anti-inflammatory properties of titanium dioxide nanotubes (TNTs) incorporated with selenium nanoparticles (SeNPs). Selenium incorporation was achieved by the reaction of sodium selenite (Na2SeO3) with glutathione (GSH) under a vacuum in the presence of TNTs. Two types of bacteria and macrophages were cultured on the samples to determine their respective antibacterial and anti-inflammatory properties. The results showed that the TNT samples incorporating SeNPs (TNT-Se) inhibited the growth of Escherichia coli and Staphylococcus aureus compared to unmodified TNTs, albeit the SeNP concentration still needs to be optimized for maximal effect. At their maximum effect, the TNT-Se samples reduced the density of E. coli by 94.6% and of S. aureus by 89.6% compared to titanium controls. To investigate the underlying mechanism of this effect, the expression of six E. coli genes were tracked using qRT-PCR. Results indicated that SeNPs weakened E. coli membranes (ompA and ompF were down-regulated), decreased the function of adhesion-mediating proteins (csgA and csgG were progressively down-regulated with increasing SeNP content), and induced the production of damaging reactive oxygen species (ahpF was up-regulated). Moreover, TNT-Se samples inhibited the proliferation of macrophages, indicating that they can be used to control the inflammatory response and even prevent chronic inflammation, a condition that often leads to implant failure. In conclusion, we demonstrated that SeNP-TNTs display antibacterial and anti-inflammatory properties that are promising for improving the performance of titanium-based implants for numerous orthopedic and dental applications. PMID:27533297

  4. Structural and electrochemical properties of PEMA with the influence of MWCNT / TiO2 filler

    NASA Astrophysics Data System (ADS)

    Pradeepa, P.; Raj, S. Edwin; Kalaiselvimary, J.; Sowmya, G.; Selvakumar, K.; Prabhu, M. Ramesh

    2016-05-01

    An attempt has been made to prepare a hybrid Nano composite polymer electrolytes (NCPES) based on Poly(ethyl methacrylate) (PEMA) doped with multiwalled carbon nanotubes (MWCNT) and Titanium oxide (TiO2) as additives, Lithium per chlorate (LiClO4) as ionic salt and Propylene Carbonate as plasticizer (PC) by using solvent casting technique. X-ray diffraction analysis (XRD) confirms the miscibility and amorphous nature of the prepared electrolytes. It has been found from the a.c impedance analysis that the inorganic filler reduces the bulk resistance of the electrolytes and thus ionic conductivity enhanced. A high dielectric loss value is observed for the case of doped MWCNT-PEMA in comparison with pure PEMA and doped TiO2 -PEMA membranes. Based on the study of relaxation spectra, it is found that the relaxation time decreases with increase in temperature.

  5. Antibacterial efficiencies of TiO2 nanostructured layers prepared in organic viscous electrolytes

    NASA Astrophysics Data System (ADS)

    Dumitriu, Cristina; Popescu, Marian; Ungureanu, Camelia; Pirvu, Cristian

    2015-06-01

    Using easy and cheap potential step anodization in electrolytes with different molar mass and water content, a Ti substrate was covered with a nanostructured TiO2 layer. Surface characterization of the prepared samples was conducted using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and contact angle analysis. The formation mechanism and surface morphologies are very different, depending on the molar mass and water percent of electrolyte solutions used for anodizing Ti substrate. The electrochemical behavior of the samples was studied using Tafel plots, and electrochemical impedance spectroscopy recorded in a simulated body fluid. All used anodizing treatments have conducted to samples with increased corrosion protection. The paper illustrates the antibacterial efficiencies of TiO2 nanostructured layers (shielded nanotubes, nanoporous oxide layer and some remaining PEG electrolyte) quantitatively estimated using gram-negative bacterium Escherichia coli ATCC 8738.

  6. Novel Bi(2)WO(6)-TiO(2) heterostructures for Rhodamine B degradation under sunlike irradiation.

    PubMed

    Murcia López, S; Hidalgo, M C; Navío, J A; Colón, G

    2011-01-30

    Highly efficient Bi(2)WO(6)-TiO(2) heterostructure is synthesized by means of a hydrothermal method having highly photoactivity for the degradation of Rhodamine B under sunlike irradiation. From the structural characterization it has been demonstrated that TiO(2) is incorporated on the Aurivillius structure. Interesting synergetic effect between TiO(2) and Bi(2)WO(6) leads to an improved charge carrier separation mechanism, causing the excellent photocatalytic performance under sunlike irradiation. The photocatalytic performance of Bi(2)WO(6) and Bi(2)WO(6)-TiO(2) was compared under different irradiation conditions and using increasing Rhodamine B concentration up to 25 ppm. After the photocatalytic analysis of both systems, the mineralization efficiency of the heterostructure appears significantly higher with respect to Bi(2)WO(6).

  7. The chemical, mechanical, and physical properties of 3D printed materials composed of TiO2-ABS nanocomposites

    PubMed Central

    Skorski, Matthew; Esenther, Jake; Ahmed, Zeeshan; Miller, Abigail E.

    2016-01-01

    To expand the chemical capabilities of 3D printed structures generated from commercial thermoplastic printers, we have produced and printed polymer filaments that contain inorganic nanoparticles. TiO2 was dispersed into acrylonitrile butadiene styrene (ABS) and extruded into filaments with 1.75 mm diameters. We produced filaments with TiO2 compositions of 1%, 5%, and 10% (kg/kg) and printed structures using a commercial 3D printer. Our experiments suggest that ABS undergoes minor degradation in the presence of TiO2 during the different processing steps. The measured mechanical properties (strain and Young’s modulus) for all of the composites are similar to those of structures printed from the pure polymer. TiO2 incorporation at 1% negatively affects the stress at breaking point and the flexural stress. Structures produced from the 5 and 10% nanocomposites display a higher breaking point stress than those printed from the pure polymer. TiO2 within the printed matrix was able to quench the intrinsic fluorescence of the polymer. TiO2 was also able to photocatalyze the degradation of a rhodamine 6G in solution. These experiments display chemical reactivity in nanocomposites that are printed using commercial 3D printers, and we expect that our methodology will help to inform others who seek to incorporate catalytic nanoparticles in 3D printed structures. PMID:27375367

  8. Modified microwave method for the synthesis of visible light-responsive TiO2/MWCNTs nanocatalysts

    PubMed Central

    2013-01-01

    Recently, TiO2/multi-walled carbon nanotube (MWCNT) hybrid nanocatalysts have been a subject of high interest due to their excellent structures, large surface areas and peculiar optical properties, which enhance their photocatalytic performance. In this work, a modified microwave technique was used to rapidly synthesise a TiO2/MWCNT nanocatalyst with a large surface area. X-ray powder diffraction, field-emission scanning electron microscopy, transmission electron microscopy and Brunauer-Emmett-Teller measurements were used to characterise the structure, morphology and the surface area of the sample. The photocatalytic activity of the hybrid nanocatalysts was evaluated through a comparison of the degradation of methylene blue dye under irradiation with ultraviolet and visible light. The results showed that the TiO2/MWCNT hybrid nanocatalysts degraded 34.9% of the methylene blue (MB) under irradiation with ultraviolet light, whereas 96.3% of the MB was degraded under irradiation with visible light. PMID:23919496

  9. Electrochemical reduction induced self-doping of Ti3+ for efficient water splitting performance on TiO2 based photoelectrodes.

    PubMed

    Zhang, Zhonghai; Hedhili, Mohamed Nejib; Zhu, Haibo; Wang, Peng

    2013-10-01

    Hetero-element doping (e.g., N, F, C) of TiO2 is inevitably accompanied by significantly increased structural defects due to the dopants' nature being foreign impurities. Very recently, in situ self-doping with homo-species (e.g., Ti(3+)) has been emerging as a rational solution to enhance TiO2 photoactivity within both UV and visible light regions. Herein we demonstrate that conventional electrochemical reduction is indeed a facile and effective strategy to induce in situ self-doping of Ti(3+) into TiO2 and the self-doped TiO2 photoelectrodes showed remarkably improved and very stable water splitting performance. In this study, hierarchical TiO2 nanotube arrays (TiO2 NTs) were chosen as TiO2 substrates and then electrochemically reduced under varying conditions to produce Ti(3+) self-doped TiO2 NTs (ECR-TiO2 NTs). The optimized saturation photocurrent density and photoconversion efficiency on the ECR-TiO2 NTs under simulated AM 1.5G illumination were identified to be 2.8 mA cm(-2) at 1.23 V vs. RHE and 1.27% respectively, which are the highest values ever reported for TiO2 based photoelectrodes. The electrochemical impedance spectra measurement confirms that the electrochemical induced Ti(3+) self-doping improved the electrical conductivity of the ECR-TiO2 NTs. The versatility and effectiveness of the electrochemical reduction method for Ti(3+) self-doping in P25 based TiO2 was also examined and confirmed.

  10. Electrochemical properties of fiber-in-tube- and filled-structured TiO2 nanofiber anode materials for lithium-ion batteries.

    PubMed

    Cho, Jung Sang; Hong, Young Jun; Kang, Yun Chan

    2015-07-27

    Phase-pure anatase TiO2 nanofibers with a fiber-in-tube structure were prepared by the electrospinning process. The burning of titanium-oxide-carbon composite nanofibers with a filled structure formed as an intermediate product under an oxygen atmosphere produced carbon-free TiO2 nanofibers with a fiber-in-tube structure. The sizes of the nanofiber core and hollow nanotube were 140 and 500 nm, respectively. The heat treatment of the electrospun nanofibers at 450 and 500 °C under an air atmosphere produced grey and white filled-structured TiO2 nanofibers, respectively. The initial discharge capacities of the TiO2 nanofibers with the fiber-in-tube and filled structures and the commercial TiO2 nanopowders were 231, 134, and 223 mA h g(-1) , respectively, and their corresponding charge capacities were 170, 100, and 169 mA h g(-1) , respectively. The 1000th discharge capacities of the TiO2 nanofibers with the fiber-in-tube and filled structures and the commercial TiO2 nanopowders were 177, 64, and 101 mA h g(-1) , respectively, and their capacity retentions measured from the second cycle were 89, 82, and 52 %, respectively. The TiO2 nanofibers with the fiber-in-tube structure exhibited low charge transfer resistance and structural stability during cycling and better cycling and rate performances than the TiO2 nanofibers with filled structures and the commercial TiO2 nanopowders. PMID:26119328

  11. Molybdenum-Loaded Anatase TiO2 Nanoparticles With Enhanced Optoelectronics Properties

    NASA Astrophysics Data System (ADS)

    Bargougui, R.; Bouazizi, N.; Ammar, S.; Azzouz, A.

    2016-09-01

    The structural, optical and electrical properties of molybdenum nanoparticles (Mo-NPs)-loaded anatase TiO2 were investigated using x-ray diffraction, UV-Vis diffuse reflectance, and Fourier transform infrared and complex impedance spectroscopy. x-ray diffraction showed that Mo-NPs incorporation induced a decrease in particle size from 30 nm to 21 nm of TiO2 and TiO2-Mo, respectively, producing a slight structure expansion. Mo-NPs dispersion resulted in a slight decrease in the optical band gap energy from 3.85 eV to 3.51 eV. Slight shifts towards higher wavelengths were attributed to the change in the acceptor capacity level induced by Mo-NPs. In addition, the ac impedance studies show the effect of Mo-NPs incorporation that appeared to be responsible for conductance of enhancement. The conduction mechanism is based on space charge-limited current via deep levels with different energy positions in the band gap. The temperature dependence of electrical properties showed that both capacitance and conductance of TiO2-Mo samples increased with increasing temperature. At low frequency, the relaxation phenomenon is related to the surface effect. The results will be beneficial to further developing titanium dioxide photo-catalysts.

  12. Colorimetric cholesterol sensor based on peroxidase like activity of zinc oxide nanoparticles incorporated carbon nanotubes.

    PubMed

    Hayat, Akhtar; Haider, Waqar; Raza, Yousuf; Marty, Jean Louis

    2015-10-01

    A sensitive and selective colorimetric method based on the incorporation of zinc oxide nanoparticles (ZnO NPs) on the surface of carbon nanotubes (CNTs) was shown to posses synergistic peroxidase like activity for the detection of cholesterol. The proposed nanocomposite catalyzed the oxidation of 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) in the presence of hydrogen peroxide (H2O2) to produce a green colored product which can be monitored at 405 nm. H2O2 is the oxidative product of cholesterol in the presence of cholesterol oxidase. Therefore, the oxidation of cholesterol can be quantitatively related to the colorimetric response by combining these two reactions. Under the optimal experimental conditions, the colorimetric response was proportional to the concentration of cholesterol in the range of 0.5-500 nmol/L, with a detection limit of 0.2 nmol/L. The applicability of the proposed assays was demonstrated for the determination of cholesterol in milk powder samples with good recovery results. PMID:26078143

  13. Tensile Properties of Polyimide Composites Incorporating Carbon Nanotubes-Grafted and Polyimide-Coated Carbon Fibers

    NASA Astrophysics Data System (ADS)

    Naito, Kimiyoshi

    2014-09-01

    The tensile properties and fracture behavior of polyimide composite bundles incorporating carbon nanotubes-grafted (CNT-grafted) and polyimide-coated (PI-coated) high-tensile-strength polyacrylonitrile (PAN)-based (T1000GB), and high-modulus pitch-based (K13D) carbon fibers were investigated. The CNT were grown on the surface of the carbon fibers by chemical vapor deposition. The pyromellitic dianhydride/4,4'-oxydianiline PI nanolayer coating was deposited on the surface of the carbon fiber by high-temperature vapor deposition polymerization. The results clearly demonstrate that CNT grafting and PI coating were effective for improving the Weibull modulus of T1000GB PAN-based and K13D pitch-based carbon fiber bundle composites. In addition, the average tensile strength of the PI-coated T1000GB carbon fiber bundle composites was also higher than that of the as-received carbon fiber bundle composites, while the average tensile strength of the CNT-grafted T1000GB, K13D, and the PI-coated K13D carbon fiber bundle composites was similar to that of the as-received carbon fiber bundle composites.

  14. Colorimetric cholesterol sensor based on peroxidase like activity of zinc oxide nanoparticles incorporated carbon nanotubes.

    PubMed

    Hayat, Akhtar; Haider, Waqar; Raza, Yousuf; Marty, Jean Louis

    2015-10-01

    A sensitive and selective colorimetric method based on the incorporation of zinc oxide nanoparticles (ZnO NPs) on the surface of carbon nanotubes (CNTs) was shown to posses synergistic peroxidase like activity for the detection of cholesterol. The proposed nanocomposite catalyzed the oxidation of 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) in the presence of hydrogen peroxide (H2O2) to produce a green colored product which can be monitored at 405 nm. H2O2 is the oxidative product of cholesterol in the presence of cholesterol oxidase. Therefore, the oxidation of cholesterol can be quantitatively related to the colorimetric response by combining these two reactions. Under the optimal experimental conditions, the colorimetric response was proportional to the concentration of cholesterol in the range of 0.5-500 nmol/L, with a detection limit of 0.2 nmol/L. The applicability of the proposed assays was demonstrated for the determination of cholesterol in milk powder samples with good recovery results.

  15. Robocasting nanocomposite scaffolds of poly(caprolactone)/hydroxyapatite incorporating modified carbon nanotubes for hard tissue reconstruction.

    PubMed

    Dorj, Biligzaya; Won, Jong-Eun; Kim, Joong-Hyun; Choi, Seong-Jun; Shin, Ueon Sang; Kim, Hae-Won

    2013-06-01

    Nanocomposite scaffolds with tailored 3D pore configuration are promising candidates for the reconstruction of bone. Here we fabricated novel nanocomposite bone scaffolds through robocasting. Poly(caprolactone) (PCL)-hydroxyapatite (HA) slurry containing ionically modified carbon nanotubes (imCNTs) was robotic-dispensed and structured layer-by-layer into macrochanneled 3D scaffolds under adjusted processing conditions. Homogeneous dispersion of imCNTs (0.2 wt % relative to PCL-HA) was achieved in acetone, aiding in the preparation of PCL-HA-imCNTs slurry with good mixing property. Incorporation of imCNTs into PCL-HA composition significantly improved the compressive strength and elastic modulus of the robotic-dispensed scaffolds (~1.5-fold in strength and ~2.5-fold in elastic modulus). When incubated in simulated body fluid (SBF), PCL-HA-imCNT nanocomposite scaffold induced substantial mineralization of apatite in a similar manner to the PCL-HA scaffold, which was contrasted in pure PCL scaffold. MC3T3-E1 cell culture on the scaffolds demonstrated that cell proliferation levels were significantly higher in both PCL-HA-imCNT and PCL-HA than in pure PCL, and no significant difference was found between the nanocomposite scaffolds. When the PCL-HA-imCNT scaffold was implanted into a rat subcutaneous tissue for 4 weeks, soft fibrous tissues with neo-blood vessels formed well in the pore channels of the scaffolds without any significant inflammatory signs. Tissue reactions in PCL-HA-imCNT scaffold were similar to those in PCL-HA scaffold, suggesting incorporated imCNT did not negate the beneficial biological roles of HA. While more long-term in vivo research in bone defect models is needed to confirm clinical availability, our results suggest robotic-dispensed PCL-HA-imCNT nanocomposite scaffolds can be considered promising new candidate matrices for bone regeneration.

  16. Photoreduction of CO2 on TiO 2/SrTiO 3 Heterojunction Network Film.

    PubMed

    Bi, Yongsheng; Zong, Lanlan; Li, Chen; Li, Qiuye; Yang, Jianjun

    2015-12-01

    Nanotube titanic acid (NTA) network film has a porous structure and large BET surface area, which lead them to possessing high utilization of the incident light and strong adsorption ability. We used NTA as the precursor to fabricate a TiO2/ SrTiO3 heterojunction film by the hydrothermal method. In the process of the reaction, part of NTA reacted with SrCl2 to form SrTiO3 nanocubes, and the remainder dehydrated to transform to the rutile TiO2. The ratio of TiO2 and SrTiO3 varied with the hydrothermal reaction time. SEM and TEM images indicated that SrTiO3 nanocubes dispersed uniformly on TiO2 film, and the particle size and crystallinity of SrTiO3 nanocubes increased with the reaction time prolonging. The TiO2/SrTiO3 heterojunction obtained by 1 h showed the best activity for CO2 photoreduction, where the mole ratio of TiO2 and SrTiO3 was 4:1. And the photo-conversion efficiency of CO2 to CH4 improved remarkably after the foreign electron traps of Pt and Pd nanoparticles were loaded. The highest photocatalytic production rate of CH4 reached 20.83 ppm/h cm(2). In addition, the selectivity of photoreduction product of CO2 was also increased apparently when Pd acted as the cocatalyst on TiO2/SrTiO3 heterojunction film.

  17. Photoreduction of CO2 on TiO2/SrTiO3 Heterojunction Network Film

    NASA Astrophysics Data System (ADS)

    Bi, Yongsheng; Zong, Lanlan; Li, Chen; Li, Qiuye; Yang, Jianjun

    2015-08-01

    Nanotube titanic acid (NTA) network film has a porous structure and large BET surface area, which lead them to possessing high utilization of the incident light and strong adsorption ability. We used NTA as the precursor to fabricate a TiO2/ SrTiO3 heterojunction film by the hydrothermal method. In the process of the reaction, part of NTA reacted with SrCl2 to form SrTiO3 nanocubes, and the remainder dehydrated to transform to the rutile TiO2. The ratio of TiO2 and SrTiO3 varied with the hydrothermal reaction time. SEM and TEM images indicated that SrTiO3 nanocubes dispersed uniformly on TiO2 film, and the particle size and crystallinity of SrTiO3 nanocubes increased with the reaction time prolonging. The TiO2/SrTiO3 heterojunction obtained by 1 h showed the best activity for CO2 photoreduction, where the mole ratio of TiO2 and SrTiO3 was 4:1. And the photo-conversion efficiency of CO2 to CH4 improved remarkably after the foreign electron traps of Pt and Pd nanoparticles were loaded. The highest photocatalytic production rate of CH4 reached 20.83 ppm/h cm2. In addition, the selectivity of photoreduction product of CO2 was also increased apparently when Pd acted as the cocatalyst on TiO2/SrTiO3 heterojunction film.

  18. Structural, photoluminescent and photocatalytic properties of TiO2:Eu3+ coatings formed by plasma electrolytic oxidation

    NASA Astrophysics Data System (ADS)

    Stojadinović, Stevan; Radić, Nenad; Grbić, Boško; Maletić, Slavica; Stefanov, Plamen; Pačevski, Aleksandar; Vasilić, Rastko

    2016-05-01

    In this paper, we used plasma electrolytic oxidation (PEO) of titanium in water solution containing 10 g/L Na3PO4·12H2O + 2 g/L Eu2O3 powder for preparation of TiO2:Eu3+ coatings. The surfaces of obtained coatings exhibit a typical PEO porous structure. The energy dispersive X-ray spectroscopy analysis showed that the coatings are mainly composed of Ti, O, P, and Eu; it is observed that Eu content in the coatings increases with PEO time. The X-ray diffraction analysis indicated that the coatings are crystallized and composed of anatase and rutile TiO2 phases, with anatase being the dominant one. X-ray photoelectron spectroscopy revealed that Ti 2p spin-orbit components of TiO2:Eu3+ coatings are shifted towards higher binding energy, with respect to pure TiO2 coatings, suggesting that Eu3+ ions are incorporated into TiO2 lattice. Diffuse reflectance spectroscopy showed that TiO2:Eu3+ coatings exhibit evident red shift with respect to the pure TiO2 coatings. Photoluminescence (PL) emission spectra of TiO2:Eu3+ coatings are characterized by sharp emission bands in orange-red region ascribed to f-f transitions of Eu3+ ions from excited level 5D0 to lower levels 7FJ (J = 0, 1, 2, 3, and 4). The excitation PL spectra of TiO2:Eu3+ coatings can be divided into two regions: the broad band region from 250 nm to 350 nm associated with charge transfer state of Eu3+ and the series of sharp peaks in the range from 350 nm to 550 nm corresponding to direct excitation of the Eu3+ ions. It is observed that the intensity of peaks in excitation and emission PL spectra increases with the concentration of Eu3+, but the peak positions remain practically unchanged. The ratio of PL emission for electric and magnetic dipole transitions indicates highly asymmetric environment around Eu3+ ions. The photocatalytic activity (PA) of TiO2:Eu3+ coatings is evaluated by measuring the photodegradation of methyl orange under simulated sunlight conditions. It is shown that PEO time, i.e., the amount

  19. Cellulose nanofiber-templated three-dimension TiO2 hierarchical nanowire network for photoelectrochemical photoanode

    NASA Astrophysics Data System (ADS)

    Li, Zhaodong; Yao, Chunhua; Wang, Fei; Cai, Zhiyong; Wang, Xudong

    2014-12-01

    Three dimensional (3D) nanostructures with extremely large porosity possess a great promise for the development of high-performance energy harvesting and storage devices. In this paper, we developed a high-density 3D TiO2 fiber-nanorod (NR) heterostructure for efficient photoelectrochemical (PEC) water splitting. The hierarchical structure was synthesized on a ZnO-coated cellulose nanofiber (CNF) template using atomic layer deposition (ALD)-based thin film and NR growth procedures. The tubular structure evolution was in good agreement with the recently discovered vapor-phase Kirkendall effect in high-temperature ALD processes. The NR morphology was formed via the surface-reaction-limited pulsed chemical vapor deposition (SPCVD) mechanism. Under Xenon lamp illumination without and with an AM 1.5G filter or a UV cut off filter, the PEC efficiencies of a 3D TiO2 fiber-NR heterostructure were found to be 22-249% higher than those of the TiO2-ZnO bilayer tubular nanofibers and TiO2 nanotube networks that were synthesized as reference samples. Such a 3D TiO2 fiber-NR heterostructure offers a new route for a cellulose-based nanomanufacturing technique, which can be used for large-area, low-cost, and green fabrication of nanomaterials as well as their utilizations for efficient solar energy harvesting and conversion.

  20. Photodegradation of Orange II by mesoporous TiO2.

    PubMed

    Kuang, Liyuan; Zhao, Yaping; Liu, Lu

    2011-09-01

    Mesoporous TiO(2) microspheres were prepared by a hydrothermal reaction and are characterized in this paper. Decoloration and mineralization during photodegradation of Orange II by mesoporous TiO(2) at different pH values, formation of sulfate, relative luminosity to luminous bacteria and recycling experiments of the catalyst were studied. The FTIR results further suggested that the novel mesoporous TiO(2) can not only decolor and mineralize dyes completely but also can be effectively reused several times. On the basis of the research, mesoporous TiO(2) would be a promising photocatalyst for practical use. PMID:21833403

  1. Correlation between dispersion properties of TiO2 colloidal sols and photoelectric characteristics of TiO2 films.

    PubMed

    Jung, Hyun Suk; Lee, Sang-Wook; Kim, Jin Young; Hong, Kug Sun; Lee, Young Cheol; Ko, Kyung Hyun

    2004-11-15

    TiO2 film for use as dye-sensitized solar cell was prepared using the TiO2 colloidal sols (unpeptized sol and peptized sol). The optical properties and photocurrent-voltage characteristics of the resultant films were investigated. The optical transmittance of TiO2 thin film prepared from the peptized colloidal sol was over 90%, while that of TiO2 film from the unpeptized sol was under 80%. The TiO2 photoelectrode prepared from the peptized colloidal sol showed low photoelectric conversion efficiency (eta), 1.30%, whereas the efficiency of photoelectrode from the unpeptized sol was 2.21%. The high optical transmittance and low conversion efficiency of TiO2 film from the peptized sol are discussed in terms of dense microstructure due to the drying nature of well-dispersed colloidal sol.

  2. The large-scale synthesis of one-dimensional TiO2 nanostructures using palladium as catalyst at low temperature.

    PubMed

    Xia, Mingxia; Zhang, Qinglin; Li, Hongxing; Dai, Guozhang; Yu, Hongchun; Wang, Taihong; Zou, Bingsuo; Wang, Yanguo

    2009-02-01

    The synthesis of TiO(2) nanostructures including nanowires and nanobelts has been demonstrated experimentally by anodization of Ti foil in an electrolyte, and by treatment in a PdCl(2) ethanol solution together with UV light irradiation and annealing at a temperature below 800 degrees C. The TiO(2) nanotube arrays resulting from the anodization were used as source precursor and transformed into nanowires and nanobelts respectively with high efficiency during the subsequent processes. The resulting TiO(2) nanowires and nanobelts, characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman and surface photovoltage (SPV) spectroscopy, are single rutile crystals of high quality. In addition to the synthesis of the nanostructure at low temperature, this method also shows great advantages for the selectable morphology of the final TiO(2) nanostructures via adjustment of the UV light irradiation time and annealing temperature.

  3. Rapid photo-degradation of 2-chlorophenol under visible light irradiation using cobalt oxide-loaded TiO2/reduced graphene oxide nanocomposite from aqueous media.

    PubMed

    Sharma, Ajit; Lee, Byeong-Kyu

    2016-01-01

    The photocatalytic removal of 2-chlorophenol (2-CP) from water environment was investigated by TiO2-RGO-CoO. Cobalt oxide-loaded TiO2 (TiO2-CoO) supported with reduced graphene oxide (RGO) was synthesized using a sol-gel method and then annealed at 500 °C for 5 min. The material characteristics were analyzed by UV-Vis analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Incorporation of cobalt oxide and RGO into the TiO2 system (TiO2-RGO-CoO) lowered the band gap energy to 2.83 eV, which greatly enhanced the visible light absorption. The TiO2-RGO-CoO photocatalyst showed complete removal of 20 mg/L 2-CP within 8 h with the addition of 0.01% H2O2 under 100 W visible light irradiation. The photo-degradation efficiency of 2-CP (10 mg/L) was 35.2, 48.9, 58.9 and 98.2% for TiO2, TiO2-RGO, TiO2-CoO and TiO2-RGO-CoO, respectively, in the presence of visible light irradiation at solution pH of 6.0. The TiO2-RGO-CoO photocatalyst retained its high removal efficiency even after five photocatalytic cycles.

  4. Nano photo scouring and nano photo bleaching of raw cellulosic fabric using nano TiO2.

    PubMed

    Montazer, M; Morshedi, S

    2012-05-01

    Photo catalytic action of nano TiO(2) for decomposing of some organic compounds is a well known phenomenon. This can be extended to the application on nano TiO(2) on the desized cotton fabric to decompose the hydrophobic impurities and coloring matters of the fabric. This can be nominating as a replacement for the conventional scouring and bleaching processes on cotton fabric producing the hydrophilic white cotton fabric. The photo activities of the nano TiO(2) on the desized cotton through decomposition of the cotton impurities compared for two different light exposures: UV rays and daylight. The desized cotton fabrics treated in the ultrasonic bath containing a colloidal aqueous solution of nano TiO(2)/citric acid (CA)/sodium hypophosphite (SHP). Incorporating CA in the treatment bath enhanced the treatment durability against washing, created a durable hydrophilic white cotton fabric even after several successive washings. Increasing the nano TiO(2) content enhanced the fabric hydrophilicity and whiteness features. Overall, the nano photo scouring and nano photo bleaching on the cotton fabric introduced and thoroughly discussed. This gains the application of nano TiO(2) on textile materials besides the other well known characteristics obtained on the textiles including self-cleaning, antibacterial and UV protection. PMID:22390850

  5. Mechanical and corrosion resistance properties of TiO2 nanoparticles reinforced Ni coating by electrodeposition

    NASA Astrophysics Data System (ADS)

    Shao, W.; Nabb, D.; Renevier, N.; Sherrington, I.; Luo, J. K.

    2012-09-01

    Coatings have been widely used in engineering and decoration to protect components and products and enhance their life span. Nickel (Ni) is one of the most important hard coatings. Improvement in its tribological and mechanical properties would greatly enhance its use in industry. Nanocomposite coatings of metals with various reinforced nanoparticles have been developed in last few decades. Titania (TiO2) exhibit excellent mechanical properties. It is believed that TiO2 incorporation in Ni matrix will improve the properties of Ni coatings significantly. The main purpose of the current work is to investigate the mechanical and anti-corrosion properties of the electroplated nickel nanocomposite with a small percentage of TiO2. The surface morphology of nanocomposite coating was characterized by scanning electron microscopy (SEM). The hardness of the nanocoating was carried out using micromaterials nanoplatform. The sliding wear rate of the coating at room temperature in dry condition was assessed by a reciprocating ball-on-disk computer-controlled oscillating tribotester. The results showed the nanocomposite coatings have a smoother and more compact surface than the pure Ni layer and have higher hardness and lower wear rate than the pure Ni coating. The anti-corrosion property of nanocomposite coating was carried out in 3.5% NaCl and high concentrated 35% NaCl solution, respectively. The results also showed that the nanocomposite coating improves the corrosion resistance significantly. This present work reveals that incorporation of TiO2 in nickel nanocomposite coating can achieve improved corrosion resistance and mechanical properties of both hardness and wear resistance performances, and the improvement becomes stronger as the content of TiO2 is increased.

  6. Optical and structural characterization of TiO2 films doped with silver nanoparticles obtained by sol-gel method

    NASA Astrophysics Data System (ADS)

    Ivanova, T.; Harizanova, A.; Koutzarova, T.; Vertruyen, B.

    2013-12-01

    Nanostructured titanium oxide films with incorporated Ag nanoparticles were deposited by sol-gel spin coating method. The films were annealed at 300 °C, 400 °C, 500 °C and 600 °C in oxygen and nitrogen ambient. X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and UV-VIS spectroscopy had been applied for studying the influence of the thermal treatments and the gas ambient on the structural and optical properties of TiO2 and TiO2:Ag films. The XRD analysis revealed the presence of metallic Ag phase without traces of silver oxides and these results were confirmed by FTIR spectra. It has been revealed that the annealing temperatures and the ambient, where the annealing is carried out is crucial for TiO2 crystallization, when there is Ag incorporation and especially for appearance of anatase and rutile phase. The nitrogen and oxygen ambient influences quite different the crystallization of TiO2:Ag films. Transmission and absorption spectra have been analyzed. Optical band gap values were evaluated for pure titania and Ag incorporated TiO2 films.

  7. Structural degradation at the surface of a TiO(2)-based nanomaterial used in cosmetics.

    PubMed

    Auffan, Mélanie; Pedeutour, Maxime; Rose, Jérôme; Masion, Armand; Ziarelli, Fabio; Borschneck, Daniel; Chaneac, Corinne; Botta, Céline; Chaurand, Perrine; Labille, Jérôme; Bottero, Jean-Yves

    2010-04-01

    A number of commercialized nanomaterials incorporate TiO(2) nanoparticles. Studying their structural stability in media mimicking the environment or the conditions of use is crucial in understanding their potential eco-toxicological effects. We focused here on a hydrophobic TiO(2) nanoparticle-based formulation used in cosmetics: T-Lite SF. It is composed of a TiO(2) core, coated with two successive protective layers of Al(OH)(3), and polydimethylsiloxane. Soon after contact with water (pH = 5, low ionic strength), the T-Lite SF becomes hydrophilic and form aggregates. During this aging, 90%wt of the total Si of the organic layer is desorbed, and the PDMS remaining at the surface is oxidized. The Al(OH)(3) layer is also affected but remains sorbed at the surface. This remaining Al-based layer still protects from the production of superoxide ions from the photoactive/phototoxic TiO(2) core in our experimental conditions.

  8. Synthesis of Metal Ion-Doped TiO2 Nanoparticles Using Two-Phase Method and Their Photocatalytic Activity Under Visible Light Irradiation.

    PubMed

    Nguyen, Duy-Trinh; Hong, Seong-Soo

    2016-02-01

    In this study, TiO2 and metal ion-doped TiO2 nanoparticles were successfully synthesized by solvothermal reaction of titanium butoxide precursor in the presence of oleic acid, oleylamine and vapor water and they were characterized by XRD, Raman, TEM and DRS. We also investigated the photocatalytic activity of these oxides for the decomposition of Rhodamine B. From XRD and Raman results, doping of the metal ion in the crystal lattice did not change the high crystallinity of the TiO2 structure, and all the metal ions were incorporated into the structures of titania as well as replaced titanium ion or located at interstitial site. The absorption band shifted to a higher wavelength on the metal ion-doped TiO2 samples compared to the pure TiO2 sample. The Ce ion- doped TiO2 catalysts showed the higher photocatalytic activity compared to the pure TiO2 and a commercial P-25 catalysts and 1% Ce-doped TiO2 showed the highest photocatalytic activity.

  9. Enhanced photoelectrochemical and photocatalytic behaviors of MFe2O4 (M = Ni, Co, Zn and Sr) modified TiO2 nanorod arrays

    NASA Astrophysics Data System (ADS)

    Gao, Xin; Liu, Xiangxuan; Zhu, Zuoming; Wang, Xuanjun; Xie, Zheng

    2016-07-01

    Modified TiO2 nanomaterials are considered to be promising in energy conversion and ferrites modification may be one of the most efficient modifications. In this research, various ferrites, incorporated with various cations (MFe2O4, M = Ni, Co, Zn, and Sr), are utilized to modify the well aligned TiO2 nanorod arrays (NRAs), which is synthesized by hydrothermal method. It is found that all MFe2O4/TiO2 NRAs show obvious red shift into the visible light region compared with the TiO2 NRAs. In particular, NiFe2O4 modification is demonstrated to be the best way to enhance the photoelectrochemical and photocatalytic activity of TiO2 NRAs. Furthermore, the separation and transfer of charge carriers after MFe2O4 modification are clarified by electrochemical impedance spectroscopy measurements. Finally, the underlying mechanism accounting for the enhanced photocatalytic activity of MFe2O4/TiO2 NRAs is proposed. Through comparison among different transition metals modified TiO2 with the same synthesis process and under the same evaluating condition, this work may provide new insight in designing modified TiO2 nanomaterials as visible light active photocatalysts.

  10. Enhanced photoelectrochemical and photocatalytic behaviors of MFe2O4 (M = Ni, Co, Zn and Sr) modified TiO2 nanorod arrays.

    PubMed

    Gao, Xin; Liu, Xiangxuan; Zhu, Zuoming; Wang, Xuanjun; Xie, Zheng

    2016-01-01

    Modified TiO2 nanomaterials are considered to be promising in energy conversion and ferrites modification may be one of the most efficient modifications. In this research, various ferrites, incorporated with various cations (MFe2O4, M = Ni, Co, Zn, and Sr), are utilized to modify the well aligned TiO2 nanorod arrays (NRAs), which is synthesized by hydrothermal method. It is found that all MFe2O4/TiO2 NRAs show obvious red shift into the visible light region compared with the TiO2 NRAs. In particular, NiFe2O4 modification is demonstrated to be the best way to enhance the photoelectrochemical and photocatalytic activity of TiO2 NRAs. Furthermore, the separation and transfer of charge carriers after MFe2O4 modification are clarified by electrochemical impedance spectroscopy measurements. Finally, the underlying mechanism accounting for the enhanced photocatalytic activity of MFe2O4/TiO2 NRAs is proposed. Through comparison among different transition metals modified TiO2 with the same synthesis process and under the same evaluating condition, this work may provide new insight in designing modified TiO2 nanomaterials as visible light active photocatalysts. PMID:27464888

  11. Synthesis of Metal Ion-Doped TiO2 Nanoparticles Using Two-Phase Method and Their Photocatalytic Activity Under Visible Light Irradiation.

    PubMed

    Nguyen, Duy-Trinh; Hong, Seong-Soo

    2016-02-01

    In this study, TiO2 and metal ion-doped TiO2 nanoparticles were successfully synthesized by solvothermal reaction of titanium butoxide precursor in the presence of oleic acid, oleylamine and vapor water and they were characterized by XRD, Raman, TEM and DRS. We also investigated the photocatalytic activity of these oxides for the decomposition of Rhodamine B. From XRD and Raman results, doping of the metal ion in the crystal lattice did not change the high crystallinity of the TiO2 structure, and all the metal ions were incorporated into the structures of titania as well as replaced titanium ion or located at interstitial site. The absorption band shifted to a higher wavelength on the metal ion-doped TiO2 samples compared to the pure TiO2 sample. The Ce ion- doped TiO2 catalysts showed the higher photocatalytic activity compared to the pure TiO2 and a commercial P-25 catalysts and 1% Ce-doped TiO2 showed the highest photocatalytic activity. PMID:27433699

  12. Enhanced photoelectrochemical and photocatalytic behaviors of MFe2O4 (M = Ni, Co, Zn and Sr) modified TiO2 nanorod arrays

    PubMed Central

    Gao, Xin; Liu, Xiangxuan; Zhu, Zuoming; Wang, Xuanjun; Xie, Zheng

    2016-01-01

    Modified TiO2 nanomaterials are considered to be promising in energy conversion and ferrites modification may be one of the most efficient modifications. In this research, various ferrites, incorporated with various cations (MFe2O4, M = Ni, Co, Zn, and Sr), are utilized to modify the well aligned TiO2 nanorod arrays (NRAs), which is synthesized by hydrothermal method. It is found that all MFe2O4/TiO2 NRAs show obvious red shift into the visible light region compared with the TiO2 NRAs. In particular, NiFe2O4 modification is demonstrated to be the best way to enhance the photoelectrochemical and photocatalytic activity of TiO2 NRAs. Furthermore, the separation and transfer of charge carriers after MFe2O4 modification are clarified by electrochemical impedance spectroscopy measurements. Finally, the underlying mechanism accounting for the enhanced photocatalytic activity of MFe2O4/TiO2 NRAs is proposed. Through comparison among different transition metals modified TiO2 with the same synthesis process and under the same evaluating condition, this work may provide new insight in designing modified TiO2 nanomaterials as visible light active photocatalysts. PMID:27464888

  13. Nickel incorporated carbon nanotube/nanofiber composites as counter electrodes for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Joshi, Prakash; Zhou, Zhengping; Poudel, Prashant; Thapa, Amit; Wu, Xiang-Fa; Qiao, Qiquan

    2012-08-01

    A nickel incorporated carbon nanotube/nanofiber composite (Ni-CNT-CNF) was used as a low cost alternative to Pt as counter electrode (CE) for dye-sensitized solar cells (DSCs). Measurements based on energy dispersive X-rays spectroscopy (EDX) showed that the majority of the composite CE was carbon at 88.49 wt%, while the amount of Ni nanoparticles was about 11.51 wt%. Measurements based on electrochemical impedance spectroscopy (EIS) showed that the charge transfer resistance (Rct) of the Ni-CNT-CNF composite electrode was 0.71 Ω cm2, much lower than that of the Pt electrode (1.81 Ω cm2). Such a low value of Rct indicated that the Ni-CNT-CNF composite carried a higher catalytic activity than the traditional Pt CE. By mixing with CNTs and Ni nanoparticles, series resistance (Rs) of the Ni-CNT-CNF electrode was measured as 5.96 Ω cm2, which was close to the Rs of 5.77 Ω cm2 of the Pt electrode, despite the significant difference in their thicknesses: ~22 μm for Ni-CNT-CNF composite, while ~40 nm for Pt film. This indicated that use of a thick layer (tens of microns) of Ni-CNT-CNF counter electrode does not add a significant amount of resistance to the total series resistance (Rs-tot) in DSCs. The DSCs based on the Ni-CNT-CNF composite CEs yielded an efficiency of 7.96% with a short circuit current density (Jsc) of 15.83 mA cm-2, open circuit voltage (Voc) of 0.80 V, and fill factor (FF) of 0.63, which was comparable to the device based on Pt, that exhibited an efficiency of 8.32% with Jsc of 15.01 mA cm-2, Voc of 0.83, and FF of 0.67.

  14. Single-walled carbon nanotube incorporated novel three phase carbon/epoxy composite with enhanced properties.

    PubMed

    Rana, Sohel; Alagirusamy, Ramasamy; Joshi, Mangala

    2011-08-01

    In the present work, single-walled carbon nanotubes were dispersed within the matrix of carbon fabric reinforced epoxy composites in order to develop novel three phase carbon/epoxy/single-walled carbon nanotube composites. A combination of ultrasonication and high speed mechanical stirring at 2000 rpm was used to uniformly disperse carbon nanotubes in the epoxy resin. The state of carbon nanotube dispersion in the epoxy resin and within the nanocomposites was characterized with the help of optical microscopy and atomic force microscopy. Pure carbon/epoxy and three phase composites were characterized for mechanical properties (tensile and compressive) as well as for thermal and electrical conductivity. Fracture surfaces of composites after tensile test were also studied in order to investigate the effect of dispersed carbon nanotubes on the failure behavior of composites. Dispersion of only 0.1 wt% nanotubes in the matrix led to improvements of 95% in Young's modulus, 31% in tensile strength, 76% in compressive modulus and 41% in compressive strength of carbon/epoxy composites. In addition to that, electrical and thermal conductivity also improved significantly with addition of carbon nanotubes.

  15. C-doped mesoporous anatase TiO2 comprising 10nm crystallites.

    PubMed

    Xie, Chong; Yang, Shenghui; Li, Beibei; Wang, Hongkong; Shi, Jian-Wen; Li, Guodong; Niu, Chunming

    2016-08-15

    We report a C-doped mesoporous anatase TiO2 with high surface area synthesized using multi-walled carbon nanotube (MWCNT) mat as a "rigid" template and carbon doping source. The characterization by SEM, HRTEM, X-ray diffraction and nitrogen adsorption revealed that TiO2 samples have a porous structure which are figuratively a inverse copy of MWCNT network and pore walls are formed by interconnected TiO2 nanoparticles with average diameter of ∼10nm. We found that annealing temperatures from 400 to 1000°C before MWCNT template removal had very limited effect on particle size (∼10nm), surface area (112-129m(2)/g) and total pore volume (0.74-0.85m(2)/g) of the samples through a significantly delayed phase transition from anatase to rutile started at 800°C, resulting in only ∼9.1% conversion at 1000°C. The pore size distribution is in mesopore range from 6 to 60nm peaked at ∼24nm. XPS analysis showed a relatively strong C1s peak at 288.4eV, indicating C doping at Ti sites, which is responsible for red shift of adsorption edge of UV-vis spectra and photocatalytic activity in visible-light region. PMID:27179173

  16. Enhanced biocompatibility of TiO2 surfaces by highly reactive plasma

    NASA Astrophysics Data System (ADS)

    Junkar, Ita; Kulkarni, Mukta; Drašler, Barbara; Rugelj, Neža; Recek, Nina; Drobne, Damjana; Kovač, Janez; Humpolicek, Petr; Iglič, Aleš; Mozetič, Miran

    2016-06-01

    In the present study the biological response to various nanotopographic features after gaseous plasma treatment were studied. The usefulness of nanostructured surfaces for implantable materials has already been acknowledged, while less is known on the combined effect of nanostructured plasma modified surfaces. In the present work the influence of oxygen plasma treatment on nanostructured titanium oxide (TiO2) surfaces was studied. Characterization of the TiO2 surface chemical composition and morphological features was analyzed after plasma modification by x-ray photoelectron spectroscopy and by scanning electron microscopy while surface wettability was studied with measuring the water contact angle. Cell adhesion and morphology was assessed from images taken with scanning electron microscopy, whereas cell viability was measured with a calorimetric assay. The obtained results showed that oxygen plasma treatment of TiO2 nanotube surfaces significantly influences the adhesion and morphology of osteoblast-like cells in comparison to untreated nanostructured surfaces. Marked changes in surface composition of plasma treated surfaces were observed, as plasma treatment removed hydrocarbon contamination and removed fluorine impurities, which were present due to the electrochemical anodization process. However no differences in wettability of untreated and plasma treated surfaces were noticed. Treatment with oxygen plasma stimulated osteoblast-like cell adhesion and spreading on the nanostructured surface, suggesting the possible use of oxygen plasma surface treatment to enhance osteoblast-like cell response.

  17. C-doped mesoporous anatase TiO2 comprising 10nm crystallites.

    PubMed

    Xie, Chong; Yang, Shenghui; Li, Beibei; Wang, Hongkong; Shi, Jian-Wen; Li, Guodong; Niu, Chunming

    2016-08-15

    We report a C-doped mesoporous anatase TiO2 with high surface area synthesized using multi-walled carbon nanotube (MWCNT) mat as a "rigid" template and carbon doping source. The characterization by SEM, HRTEM, X-ray diffraction and nitrogen adsorption revealed that TiO2 samples have a porous structure which are figuratively a inverse copy of MWCNT network and pore walls are formed by interconnected TiO2 nanoparticles with average diameter of ∼10nm. We found that annealing temperatures from 400 to 1000°C before MWCNT template removal had very limited effect on particle size (∼10nm), surface area (112-129m(2)/g) and total pore volume (0.74-0.85m(2)/g) of the samples through a significantly delayed phase transition from anatase to rutile started at 800°C, resulting in only ∼9.1% conversion at 1000°C. The pore size distribution is in mesopore range from 6 to 60nm peaked at ∼24nm. XPS analysis showed a relatively strong C1s peak at 288.4eV, indicating C doping at Ti sites, which is responsible for red shift of adsorption edge of UV-vis spectra and photocatalytic activity in visible-light region.

  18. A high-performance nonenzymatic piezoelectric sensor based on molecularly imprinted transparent TiO2 film for detection of urea.

    PubMed

    Yang, Zheng-peng; Liu, Xuan; Zhang, Chun-jing; Liu, Bao-zhong

    2015-12-15

    Transparent photocatalytic surfaces are of ever increasing importance for the enhancement of the photocatalytic efficiency. Here, the highly ordered transparent TiO2 nanotube arrays were prepared by the anodization and thermal annealing of titanium layer deposited onto the glass substrate, and a novel nonenzymatic piezoelectric sensor was developed for urea detection based on the modification of molecularly imprinted TiO2 thin film onto transparent TiO2 nanotube arrays. The performance of the fabricated sensor was evaluated and the results indicated that the sensor exhibited high sensitivity in urea detection, with a linear range from 0.04 to 120 μM and a limit of detection of 0.01 μM. Moreover, the sensor presented outstanding selectivity while used in coexisting systems containing various interferents with high concentration. The analytical application of the urea sensor confirmed the feasibility of urea detection in urine sample.

  19. Graphene-embedded 3D TiO2 inverse opal electrodes for highly efficient dye-sensitized solar cells: morphological characteristics and photocurrent enhancement.

    PubMed

    Kim, Hye-Na; Yoo, Haemin; Moon, Jun Hyuk

    2013-05-21

    We demonstrated the preparation of graphene-embedded 3D inverse opal electrodes for use in DSSCs. The graphene was incorporated locally into the top layers of the inverse opal structures and was embedded into the TiO2 matrix via post-treatment of the TiO2 precursors. DSSCs comprising the bare and 1-5 wt% graphene-incorporated TiO2 inverse opal electrodes were compared. We observed that the local arrangement of graphene sheets effectively enhanced electron transport without significantly reducing light harvesting by the dye molecules. A high efficiency of 7.5% was achieved in DSSCs prepared with the 3 wt% graphene-incorporated TiO2 inverse opal electrodes, constituting a 50% increase over the efficiencies of DSSCs prepared without graphene. The increase in efficiency was mainly attributed to an increase in J(SC), as determined by the photovoltaic parameters and the electrochemical impedance spectroscopy analysis. PMID:23536037

  20. Graphene-embedded 3D TiO2 inverse opal electrodes for highly efficient dye-sensitized solar cells: morphological characteristics and photocurrent enhancement.

    PubMed

    Kim, Hye-Na; Yoo, Haemin; Moon, Jun Hyuk

    2013-05-21

    We demonstrated the preparation of graphene-embedded 3D inverse opal electrodes for use in DSSCs. The graphene was incorporated locally into the top layers of the inverse opal structures and was embedded into the TiO2 matrix via post-treatment of the TiO2 precursors. DSSCs comprising the bare and 1-5 wt% graphene-incorporated TiO2 inverse opal electrodes were compared. We observed that the local arrangement of graphene sheets effectively enhanced electron transport without significantly reducing light harvesting by the dye molecules. A high efficiency of 7.5% was achieved in DSSCs prepared with the 3 wt% graphene-incorporated TiO2 inverse opal electrodes, constituting a 50% increase over the efficiencies of DSSCs prepared without graphene. The increase in efficiency was mainly attributed to an increase in J(SC), as determined by the photovoltaic parameters and the electrochemical impedance spectroscopy analysis.