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Sample records for tio2 nanorods branched

  1. Charge separation in branched TiO_2 nanorod array homojunction aroused by quantum effect for enhanced photocatalytic decomposition of gaseous benzene

    International Nuclear Information System (INIS)

    Wang, Xiaoxia; Ni, Qian; Zeng, Dawen; Liao, Guanglan; Xie, Changsheng

    2016-01-01

    Highlights: • Charge separation in homojunction based on the broadened band gap by quantum effect. • Absolute charge separation by the passivation effect of TiO_2 nanorod. • Long-distance electron transfer behavior in photocatalysis. • Roughed surface for enhanced light harvesting by light trapping effect. - Abstract: As known, the electron transfer behavior in photocatalysis is short-distance transportation, which leads the photo-induced electrons and holes to be localized. The temporarily separated electrons and holes will recombine with each other in the localized region. In this paper, we successfully achieved electron transfer in a homojunction of branched rutile TiO_2 nanorod @nanoparticle core-shell architecture by quantum confinement effect aroused by the nanoparticle, which is proved by the blue-shifting in UV–vis absorption spectrum of the homojunction. Meanwhile, an absolute charge separation is also achieved by the long-distance electron transfer along the single-crystalline rutile TiO_2 nanorod as uninterrupted high-speed electron transfer channel to FTO substrates. Based on the effective charge separation, the photocatalytic decomposition of gaseous benzene by the homojunction is significantly enhanced, yielding 10 times CO_2 than that of the nanorod array. This homojunction interfacial charge separation, aroused by quantum effect, through long-distance transfer along the single-crystalline nanorod gives us inspiration to achieve efficient charge separation with defect-less interfaces, which might can be utilized for real-time environmental abatement and energy generation simultaneously.

  2. Three-dimensional self-branching anatase TiO_2 nanorods with the improved carrier collection for SrTiO_3-based perovskite solar cells

    International Nuclear Information System (INIS)

    Hu, Yajing; Wang, Chen; Tang, Ying; Huang, Lu; Fu, Jianxun; Shi, Weimin; Wang, Linjun; Yang, Weiguang

    2016-01-01

    The organic–inorganic perovskite solar cells based on ternary oxide SrTiO_3 shows a higher Voc, attributed to its slightly higher conduction band edge and better morphology of absorber material. However, its less efficient carrier collection and limited overall interfacial areas between the absorber material and the electron-transport layer (ETL), dramatically reducing the Jsc. Here, By adjusting the concentrations of the Ti(OBu)_4, we successfully prepared the three-dimensional (3D) self-branching anatase TiO_2 nanorod/SrTiO_3 nanocomposites, and slightly tuned the particle size of SrTiO_3. With the incorporation of the three-dimensional (3D) self-branching anatase TiO_2 nanorod, the Jsc of the device based on SrTiO_3 was highly boosted. The best performing solar cell we obtained exhibited a PCE of 9.99% with a Jsc of 19.48 mA/cm"2. The excellent performance could be ascribed to the improvement of charge carrier collection of SrTiO_3, better surface coverage and crystallinity of CH_3NH_3PbI_3, and enhanced light scattering ability caused by 3D self-branching anatase TiO_2 nanorods. - Highlights: • The three-dimensional (3D) self-branching anatase TiO_2 nanorod/SrTiO_3 nanocomposites were prepared. • The particle sizes of SrTiO_3 can be slightly tuned. • The best performing solar cell we obtained exhibited a PCE of 9.99% with the Jsc of 19.48 mA/cm"2.

  3. Dye-Sensitized Solar Cells with Anatase TiO2 Nanorods Prepared by Hydrothermal Method

    Directory of Open Access Journals (Sweden)

    Ming-Jer Jeng

    2013-01-01

    Full Text Available The hydrothermal method provides an effective reaction environment for the synthesis of nanocrystalline materials with high purity and well-controlled crystallinity. In this work, we started with various sizes of commercial TiO2 powders and used the hydrothermal method to prepare TiO2 thin films. We found that the synthesized TiO2 nanorods were thin and long when smaller TiO2 particles were used, while larger TiO2 particles produced thicker and shorter nanorods. We also found that TiO2 films prepared by TiO2 nanorods exhibited larger surface roughness than those prepared by the commercial TiO2 particles. It was found that a pure anatase phase of TiO2 nanorods can be obtained from the hydrothermal method. The dye-sensitized solar cells fabricated with TiO2 nanorods exhibited a higher solar efficiency than those fabricated with commercial TiO2 nanoparticles directly. Further, triple-layer structures of TiO2 thin films with different particle sizes were investigated to improve the solar efficiency.

  4. Y-doping TiO2 nanorod arrays for efficient perovskite solar cells

    Science.gov (United States)

    Deng, Xinlian; Wang, Yanqing; Cui, Zhendong; Li, Long; Shi, Chengwu

    2018-05-01

    To improve the electron transportation in TiO2 nanorod arrays and charge separation in the interface of TiO2/perovskite, Y-doping TiO2 nanorod arrays with the length of 200 nm, diameter of 11 nm and areal density of 1050 μm-2 were successfully prepared by the hydrothermal method and the influence of Y/Ti molar ratios of 0%, 3%, 5% in the hydrothermal grown solutions on the growth of TiO2 nanorod arrays was investigated. The results revealed that the appropriate Y/Ti molar ratios can increase the areal density of the corresponding TiO2 nanorod arrays and improve the charge separation in the interface of the TiO2/perovskite. The Y-doping TiO2 nanorod array perovskite solar cells with the Y/Ti molar ratio of 3% exhibited a photoelectric conversion efficiency (PCE) of 18.11% along with an open-circuit voltage (Voc) of 1.06 V, short-circuit photocurrent density (Jsc) of 22.50 mA cm-2 and fill factor (FF) of 76.16%, while the un-doping TiO2 nanorod array perovskite solar cells gave a PCE of 16.42% along with Voc of 1.04 V, Jsc of 21.66 mA cm-2 and FF of 72.97%.

  5. Thiourea-Modified TiO2 Nanorods with Enhanced Photocatalytic Activity

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    Xiaofeng Wu

    2016-02-01

    Full Text Available Semiconductor TiO2 photocatalysis has attracted much attention due to its potential application in solving the problems of environmental pollution. In this paper, thiourea (CH4N2S modified anatase TiO2 nanorods were fabricated by calcination of the mixture of TiO2 nanorods and thiourea at 600 °C for 2 h. It was found that only N element was doped into the lattice of TiO2 nanorods. With increasing the weight ratio of thiourea to TiO2 (R from 0 to 8, the light-harvesting ability of the photocatalyst steady increases. Both the crystallization and photocatalytic activity of TiO2 nanorods increase first and then decrease with increase in R value, and R2 sample showed the highest crystallization and photocatalytic activity in degradation of Brilliant Red X3B (X3B and Rhodamine B (RhB dyes under visible light irradiation (λ > 420 nm. The increased visible-light photocatalytic activity of the prepared N-doped TiO2 nanorods is due to the synergistic effects of the enhanced crystallization, improved light-harvesting ability and reduced recombination rate of photo-generated electron-hole pairs. Note that the enhanced visible photocatalytic activity of N-doped nanorods is not based on the scarification of their UV photocatalytic activity.

  6. Enhanced photoelectrochemical properties of TiO2 nanorod arrays decorated with CdS nanoparticles

    International Nuclear Information System (INIS)

    Xie, Zheng; Wang, Weipeng; Liu, Can; Li, Zhengcao; Liu, Xiangxuan; Zhang, Zhengjun

    2014-01-01

    TiO 2 nanorod arrays (TiO 2 NRAs) sensitized with CdS nanoparticles were fabricated via successive ion layer adsorption and reaction (SILAR), and TiO 2 NRAs were obtained by oxidizing Ti NRAs obtained through oblique angle deposition. The TiO 2 NRAs decorated with CdS nanoparticles exhibited excellent photoelectrochemical and photocatalytic properties under visible light, and the one decorated with 20 SILAR cycles CdS nanoparticles shows the best performance. This can be attributed to the enhanced separation of electrons and holes by forming heterojunctions of CdS nanoparticles and TiO 2 NRAs. This provides a promising way to fabricate the material for solar energy conversion and wastewater degradation. (paper)

  7. Digital selective fabrication of micro/nano-composite structured TiO2 nanorod arrays by laser direct writing

    Science.gov (United States)

    Jiang, Wei; He, Xiaoning; Liu, Hongzhong; Yin, Lei; Shi, Yongsheng; Ding, Yucheng

    2014-11-01

    In this article, we report on the digital selective fabrication of micro/nano-composite structured TiO2 nanorod arrays by laser direct writing. The pattern of TiO2 nanorod arrays can be easily designed and fabricated by laser scanning technology integrated with a computer-aided design system, which allows a high degree of freedom corresponding to the various pattern design demands. The approach basically involves the hydrothermal growth of TiO2 nanorod arrays on a transparent conductive substrate, the micropattern of TiO2 nanorod arrays and surface fluorination treatment. With these micro/nano-composite TiO2 nanorod array based films, we have demonstrated superhydrophilic patterned TiO2 nanorod arrays with rapid water spreading ability and superhydrophobic patterned TiO2 nanorod arrays with an excellent droplet bouncing effect and a good self-cleaning performance. The dynamic behaviours of the water droplets observed on the patterned TiO2 nanorod arrays were demonstrated by experiments and simulated by a finite element method. The approaches we will show are expected to provide potential applications in fields such as self-cleaning, surface protection, anticrawling and microfluidic manipulation.

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

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  9. Photoelectrochemical properties of the TiO2-ZnO nanorod hierarchical structure prepared by hydrothermal process

    Directory of Open Access Journals (Sweden)

    Bao SUN

    2018-02-01

    Full Text Available In order to increase the transport channels of the photogenerated electrons and enhance the photosensitizer loading ability of the electrode, a new TiO2-ZnO nanorod hierarchical structure is prepared through two-step hydrothermal process. First, TiO2 nanorod array is grown on the FTO conductive glass substrate by hydrothermal proess. Then, ZnO sol is coated onto the TiO2 nanorods through dip-coating method and inverted to ZnO seed layer by sintering. Finally, the secondary ZnO nanorods are grown onto the TiO2 nanorods by the sencond hydrothermal method to form the designed TiO2-ZnO nanorod hierarchical structure. A spin-coating assisted successive ionic layer reaction method (SC-SILR is used to deposit the CdS nanocrystals into the TiO2 nanorod array and the TiO2-ZnO nanorod hierarchical structure is used to form the CdS/TiO2 and CdS/TiO2-ZnO nanocomposite films. Different methods, such as SEM, TEM, XRD, UV-Vis and transient photocurrent, are employed to characterize and measure the morphologies, structures, light absorption and photoelectric conversion performance of all the samples, respectively. The results indicate that, compared with the pure TiO2 nanorod array, the TiO2-ZnO nanorod hierarchical structure can load more CdS photosensitizer. The light absorption properties and transient photocurrent performance of the CdS/TiO2-ZnO nanorod hierarchical structure composite film are evidently superior to that of the CdS/TiO2 nanocomposite films. The excellent photoelctrochemical performance of theTiO2-ZnO hierarchical structure reveales its application prospect in photoanode material of the solar cells.

  10. TiO2 Nanorods Decorated with Pd Nanoparticles for Enhanced Liquefied Petroleum Gas Sensing Performance.

    Science.gov (United States)

    Dhawale, Dattatray S; Gujar, Tanaji P; Lokhande, Chandrakant D

    2017-08-15

    Development of highly sensitive and selective semiconductor-based metal oxide sensor devices to detect toxic, explosive, flammable, and pollutant gases is still a challenging research topic. In the present work, we systematically enhanced the liquefied petroleum gas (LPG) sensing performance of chemical bath deposited TiO 2 nanorods by decorating Pd nanoparticle catalyst. Surface morphology with elemental mapping, crystal structure, composition and oxidation states, and surface area measurements of pristine TiO 2 and Pd:TiO 2 nanorods was examined by high resolution transmission electron microscopy with energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and nitrogen adsorption-desorption characterization techniques. LPG sensing performance of pristine TiO 2 and Pd:TiO 2 nanorods was investigated in different LPG concentration and operating temperature ranges. The LPG response of 21% for pristine TiO 2 nanorods is enhanced to 49% after Pd catalyst decoration with reasonably fast response and recovery times. Further, the sensor exhibited long-term stability, which could be due to the strong metal support (Pd:TiO 2 ) interaction and catalytic properties offered by the Pd nanoparticle catalyst. The work described herein demonstrates a general and scalable approach that provides a promising route for rational design of variety of sensor devices for LPG detection.

  11. Synthesis and characterization of TiO2/CdS core–shell nanorod arrays and their photoelectrochemical property

    International Nuclear Information System (INIS)

    Cao Chunlan; Hu Chenguo; Shen Weidong; Wang, Shuxia; Tian Yongshu; Wang Xue

    2012-01-01

    Highlights: ► TiO 2 /CdS core–shell nanorod arrays were fabricated by spin-SILAR method. ► The enhanced photocurrent was found in the TiO 2 /CdS core–shell nanorod arrays. ► The CdS coated on TiO 2 increases the e-h separation and enlarges light absorption range. - Abstract: TiO 2 /CdS core–shell nanorod arrays have been fabricated via a two-step method. Vertically aligned TiO 2 nanorod arrays (NRs) were synthesized by a facile hydrothermal method, and followed by depositing CdS nanoparticles on TiO 2 NRs by spin-coating successive ion layer adsorption and reaction (spin-SILAR) method. The surface morphology, structure, optical and photoelectrochemical behaviors of the core–shell NRs films are considered. The UV–vis absorption spectrum results suggested that the absorption peak of the TiO 2 /CdS core–shell NRs shifts from the ultraviolet region to the visible region in comparison to that of the pure TiO 2 NRs. The obviously enhanced photoelectrochemical (PEC) performances of the heterojunction NRs were found under illumination of the simulated sunlight in comparison with that of the TiO 2 NRs. The enhanced PEC performance and formation mechanism of TiO 2 /CdS core–shell NRs were discussed in detail.

  12. Rutile TiO2 nanorod arrays directly grown on Ti foil substrates towards lithium-ion micro-batteries

    International Nuclear Information System (INIS)

    Dong Shanmu; Wang Haibo; Gu Lin; Zhou Xinhong; Liu Zhihong; Han Pengxian; Wang Ya; Chen Xiao; Cui Guanglei; Chen Liquan

    2011-01-01

    Nanosized rutile TiO 2 is one of the most promising candidates for anode material in lithium-ion micro-batteries owing to their smaller dimension in ab-plane resulting in an enhanced performance for area capacity. However, few reports have yet emerged up to date of rutile TiO 2 nanorod arrays growing along c-axis for Li-ion battery electrode application. In this study, single-crystalline rutile TiO 2 nanorod arrays growing directly on Ti foil substrates have been fabricated using a template-free method. These nanorods can significantly improve the electrochemical performance of rutile TiO 2 in Li-ion batteries. The capacity increase is about 10 times in comparison with rutile TiO 2 compact layer.

  13. Chemical synthesis of CdS onto TiO2 nanorods for quantum dot sensitized solar cells

    Science.gov (United States)

    Pawar, Sachin A.; Patil, Dipali S.; Lokhande, Abhishek C.; Gang, Myeng Gil; Shin, Jae Cheol; Patil, Pramod S.; Kim, Jin Hyeok

    2016-08-01

    A quantum dot sensitized solar cell (QDSSC) is fabricated using hydrothermally grown TiO2 nanorods and successive ionic layer adsorption and reaction (SILAR) deposited CdS. Surface morphology of the TiO2 films coated with different SILAR cycles of CdS is examined by Scanning Electron Microscopy which revealed aggregated CdS QDs coverage grow on increasing onto the TiO2 nanorods with respect to cycle number. Under AM 1.5G illumination, we found the TiO2/CdS QDSSC photoelectrode shows a power conversion efficiency of 1.75%, in an aqueous polysulfide electrolyte with short-circuit photocurrent density of 4.04 mA/cm2 which is higher than that of a bare TiO2 nanorods array.

  14. TiO2 nanorods/PMMA copolymer-based nanocomposites: highly homogeneous linear and nonlinear optical material

    International Nuclear Information System (INIS)

    Sciancalepore, C; Agostiano, A; Cassano, T; Valentini, A; Curri, M L; Striccoli, M; Mecerreyes, D; Tommasi, R

    2008-01-01

    Original nanocomposites have been obtained by direct incorporation of pre-synthesized oleic acid capped TiO 2 nanorods into properly functionalized poly(methyl methacrylate) copolymers, carrying carboxylic acid groups on the repeating polymer unit. The presence of carboxylic groups on the alkyl chain of the host functionalized copolymer allows an highly homogeneous dispersion of the nanorods in the organic matrix. The prepared TiO 2 /PMMA-co-MA nanocomposites show high optical transparency in the visible region, even at high TiO 2 nanorod content, and tunable linear refractive index depending on the nanoparticle concentration. Finally measurements of nonlinear optical properties of TiO 2 polymer nanocomposites demonstrate a negligible two-photon absorption and a negative value of nonlinear refractive index, highlighting the potential of the nanocomposite for efficient optical devices operating in the visible region

  15. TiO2 nanorods/PMMA copolymer-based nanocomposites: highly homogeneous linear and nonlinear optical material

    Science.gov (United States)

    Sciancalepore, C.; Cassano, T.; Curri, M. L.; Mecerreyes, D.; Valentini, A.; Agostiano, A.; Tommasi, R.; Striccoli, M.

    2008-05-01

    Original nanocomposites have been obtained by direct incorporation of pre-synthesized oleic acid capped TiO2 nanorods into properly functionalized poly(methyl methacrylate) copolymers, carrying carboxylic acid groups on the repeating polymer unit. The presence of carboxylic groups on the alkyl chain of the host functionalized copolymer allows an highly homogeneous dispersion of the nanorods in the organic matrix. The prepared TiO2/PMMA-co-MA nanocomposites show high optical transparency in the visible region, even at high TiO2 nanorod content, and tunable linear refractive index depending on the nanoparticle concentration. Finally measurements of nonlinear optical properties of TiO2 polymer nanocomposites demonstrate a negligible two-photon absorption and a negative value of nonlinear refractive index, highlighting the potential of the nanocomposite for efficient optical devices operating in the visible region.

  16. Influence of Zr doping on structure and morphology of TiO2 nanorods prepared using hydrothermal method

    Science.gov (United States)

    Muslimin, Masliana; Jumali, Mohammad Hafizuddin; Tee, Tan Sin; Beng, Lee Hock; Hui, Tan Chun; Chin, Yap Chi

    2018-04-01

    The aim of this work is to investigate the effect of Zr doping on TiO2 nanostructure. TiO2 nanorods thin films with different Zr-doping concentrations (6 × 10-3 M, 13 × 10-3 M and 25 × 10-3 M) were successfully prepared using a simple hydrothermal method. The structural and morphological properties of the samples were evaluated using XRD and FESEM respectively. The XRD results revealed that the TiO2 in all samples stabilized as rutile phase. The FESEM micrographs confirmed that TiO2 exist as square like nanorods with blunt tips. Although the crystallographic nature remains unchanged, the introduction of Zr has altered the surface density, structure and morphology of TiO2 which subsequently will have significant effect on its properties.

  17. Template-free formation of vertically oriented TiO2 nanorods with uniform distribution for organics-sensing application

    International Nuclear Information System (INIS)

    Mu Qinghui; Li Yaogang; Zhang Qinghong; Wang Hongzhi

    2011-01-01

    Graphical abstract: - Abstract: High-density arrays of vertically oriented TiO 2 nanorods with uniform distribution on Ti foil have been formed through template-free oxidation of Ti in hydrogen peroxide solutions. Subsequent thermal treatment was applied for growing mixed crystal structures to pursue higher performance. Morphology characterization using field emission scanning electron microscopy (FESEM) shows a nanorod diameter in the range of 20-50 nm with a length of 1.5 μm. X-ray diffraction (XRD) measurement demonstrates the crystallization of the TiO 2 nanorods prior to thermal treatment and the formation of anatase and rutile mixed phase after thermal treatment. The mixed crystal TiO 2 nanorods show a much higher performance than pure anatase in photoelectrochemical experiments. Steady-state photocurrent resulted from photocatalytic oxidation of organic compounds by TiO 2 nanorods is employed as response signal in determination of the organics to yield a linear range of 0-1.1 mM for glucose. For other organics, an excellent linear relationship between the net steady-state photocurrent and the concentration of electrons transferred in exhaustive oxidation for these organics is obtained, which empowers the mixed crystal TiO 2 nanorods to serve as versatile material in organics-sensing application.

  18. Superior environment resistance of quartz crystal microbalance with anatase TiO2/ZnO nanorod composite films

    International Nuclear Information System (INIS)

    Qiang, Wei; Wei, Li; Shaodan, Wang; Yu, Bai

    2015-01-01

    Graphical abstract: ZnO nanorod array being prepared by an in situ method on the QCM coated with Au film via hydrothermal process and surface modification with coated TiO 2 by sol–gel methods to form a superhydrophobic TiO 2 /ZnO composite film the anatase TiO 2 /ZnO nanorod composite film with a sharp, pencil-like structure exhibiting excellent superhydrophobicity (water contact angle of 155°), non-sticking water properties, and an autonomous cleaning property under UV irradiation. The anatase TiO 2 /ZnO nanorod composite film facilitates the precise measurement and extended lifetime of the QCM for the detection of organic gas molecules. - Highlights: • This work combines, for the first time, the advantage of the TiO 2 /ZnO composite film on photocatalysis and reversible super-hydrophobic and super-hydrophilic transition, and puts forward a solution to satisfy weatherability of quartz crystal microbalance in long-term application. • The anatase TiO 2 /ZnO nanorod composite film with pencil structure exhibit excellent super-hydrophobicity (water contact angle can reach 155°), no-sticking water properties and self-cleaning property under UV irradiation. • The photocatalysis and reversible super-hydrophobic and super-hydrophilic transition of the TiO 2 /ZnO nanorod composite film is stable in long-term application. - Abstract: The precise measurement of quartz crystal microbalance (QCM) in the detection and weighing of organic gas molecules is achieved due to excellent superhydrophobicity of a deposited film composite. Photocatalysis is utilized as a method for the self-cleaning of organic molecules on the QCM for extended long-term stability in the precision of the instrument. In this paper, ZnO nanorod array is prepared via in situ methods on the QCM coated with Au film via hydrothermal process. Subsequently, a TiO 2 /ZnO composite film is synthesized by surface modification with TiO 2 via sol–gel methods. Results show the anatase TiO 2 /ZnO nanorod

  19. Electrochemical properties of TiO2 encapsulated ZnO nanorod aggregates dye sensitized solar cells

    International Nuclear Information System (INIS)

    Justin Raj, C.; Karthick, S.N.; Dennyson Savariraj, A.; Hemalatha, K.V.; Park, Song-Ki; Kim, Hee-Je; Prabakar, K.

    2012-01-01

    Highlights: ► ZnO nanorod aggregates were synthesized by simple co-precipitation technique. ► TiO 2 encapsulated ZnO nanorod aggregates photoanode was used for the DSSC. ► TiO 2 encapsulated ZnO nanorod aggregates shows an enhanced efficiency. ► The electron recombination and transport properties were studied using EIS method. - Abstract: Dye sensitized solar cells based on TiO 2 encapsulated ZnO nanorod (NR) aggregates were fabricated and electrochemical performance was analyzed using impedance spectroscopy as a function of forward bias voltage. Charge transfer properties such as electron life time (τ n ), electron diffusion coefficient (D n ) and electron diffusion length (L n ) were calculated in order to ensure the influence of TiO 2 layer over the ZnO NR aggregates. It is found that the short circuit current density (Jsc = 5.8 mA cm −2 ), open circuit potential (V oc = 0.743 V), fill factor (FF = 0.57) and conversion efficiency are significantly improved by the introduction of TiO 2 layer over ZnO photoanode. A power conversion efficiency of about 2.48% has been achieved for TiO 2 /ZnO cell, which is higher than that of bare ZnO NR aggregate based cells (1.73%). The formation of an inherent energy barrier between TiO 2 and ZnO films and the passivation of surface traps on the ZnO film caused by the introduction of TiO 2 layer increase the dye absorption and favor the electron transport which may be responsible for the enhanced performance of TiO 2 /ZnO cell.

  20. Synthesis of TiO2 nanorod-decorated graphene sheets and their highly efficient photocatalytic activities under visible-light irradiation

    International Nuclear Information System (INIS)

    Lee, Eunwoo; Hong, Jin-Yong; Kang, Haeyoung; Jang, Jyongsik

    2012-01-01

    Highlights: ► TiO 2 nanorods were successfully decorated on the surface of graphene sheets. ► Population of TiO 2 nanorods can be controlled by changing experimental conditions. ► TiO 2 nanorod-decorated graphene sheets have an expanded light absorption range. ► TiO 2 nanorod-decorated graphene sheets showed unprecedented photocatalytic activity. - Abstract: The titanium dioxide (TiO 2 ) nanorod-decorated graphene sheets photocatalysts with different TiO 2 nanorods population have been synthesized by a simple non-hydrolytic sol–gel approach. Electron microscopy and X-ray diffraction analysis indicated that the TiO 2 nanorods are well-dispersed and successfully anchored on the graphene sheet surface through the formation of covalent bonds between Ti and C atoms. The photocatalytic activities are evaluated in terms of the efficiencies of photodecomposition and adsorption of methylene blue (MB) in aqueous solution under visible-light irradiation. The as-synthesized TiO 2 nanorod-decorated graphene sheets showed unprecedented photodecomposition efficiency compared to the pristine TiO 2 nanorods and the commercial TiO 2 (P-25, Degussa) under visible-light. It is believed that this predominant photocatalytic activity is due to the synergistic contribution of both a retarded charge recombination rate caused by a high electronic mobility of graphene and an increased surface area originated from nanometer-sized TiO 2 nanorods. Furthermore, photoelectrochemical study is performed to give deep insights into the primary roles of graphene that determines the photocatalytic activity.

  1. Vertically aligned TiO2 nanorods-woven carbon fiber for reinforcement of both mechanical and anti-wear properties in resin composite

    Science.gov (United States)

    Fei, Jie; Zhang, Chao; Luo, Dan; Cui, Yali; Li, Hejun; Lu, Zhaoqing; Huang, Jianfeng

    2018-03-01

    A series of TiO2 nanorods were successfully grown on woven carbon fiber by hydrothermal method to reinforce the resin composite. The TiO2 nanorods improved the mechanical interlocking among woven carbon fibers and resin matrix, resulting in better fibers/resin interfacial bonding. Compared with desized-woven carbon fiber, the uniform TiO2 nanorods array resulted in an improvement of 84.3% and 73.9% in the tensile and flexural strength of the composite. However, the disorderly TiO2 nanorods on woven carbon fiber leaded to an insignificant promotion of the mechanical strength. The enhanced performance of well-proportioned TiO2 nanorods-woven carbon fiber was also reflected in the nearly 56% decrease of wear rate, comparing to traditional woven carbon fiber reinforced composite.

  2. Enhancement of Perovskite Solar Cells Efficiency using N-Doped TiO2 Nanorod Arrays as Electron Transfer Layer.

    Science.gov (United States)

    Zhang, Zhen-Long; Li, Jun-Feng; Wang, Xiao-Li; Qin, Jian-Qiang; Shi, Wen-Jia; Liu, Yue-Feng; Gao, Hui-Ping; Mao, Yan-Li

    2017-12-01

    In this paper, N-doped TiO 2 (N-TiO 2 ) nanorod arrays were synthesized with hydrothermal method, and perovskite solar cells were fabricated using them as electron transfer layer. The solar cell performance was optimized by changing the N doping contents. The power conversion efficiency of solar cells based on N-TiO 2 with the N doping content of 1% (N/Ti, atomic ratio) has been achieved 11.1%, which was 14.7% higher than that of solar cells based on un-doped TiO 2 . To get an insight into the improvement, some investigations were performed. The structure was examined with X-ray powder diffraction (XRD), and morphology was examined by scanning electron microscopy (SEM). Energy dispersive spectrometer (EDS) and Tauc plot spectra indicated the incorporation of N in TiO 2 nanorods. Absorption spectra showed higher absorption of visible light for N-TiO 2 than un-doped TiO 2 . The N doping reduced the energy band gap from 3.03 to 2.74 eV. The photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectra displayed the faster electron transfer from perovskite layer to N-TiO 2 than to un-doped TiO 2 . Electrochemical impedance spectroscopy (EIS) showed the smaller resistance of device based on N-TiO 2 than that on un-doped TiO 2 .

  3. Visible Light Photoelectrochemical Properties of N-Doped TiO2 Nanorod Arrays from TiN

    Directory of Open Access Journals (Sweden)

    Zheng Xie

    2013-01-01

    Full Text Available N-doped TiO2 nanorod arrays (NRAs were prepared by annealing the TiN nanorod arrays (NRAs which were deposited by using oblique angle deposition (OAD technique. The TiN NRAs were annealed at 330°C for different times (5, 15, 30, 60, and 120 min. The band gaps of annealed TiN NRAs (i.e., N-doped TiO2 NRAs show a significant variance with annealing time, and can be controlled readily by varying annealing time. All of the N-doped TiO2 NRAs exhibit an enhancement in photocurrent intensity in visible light compared with that of pure TiO2 and TiN, and the one annealed for 15 min shows the maximum photocurrent intensity owning to the optimal N dopant concentration. The results show that the N-doped TiO2 NRAs, of which the band gap can be tuned easily, are a very promising material for application in photocatalysis.

  4. Fabrication of TiO2 nanoparticles/nanorod composite arrays via a two-step method for efficient dye-sensitized solar cells

    Directory of Open Access Journals (Sweden)

    Jingyang Wang

    2014-12-01

    Full Text Available TiO2 nanoparticles/nanorod composite arrays were prepared on the F-doped tin oxide (FTO substrate through a two-step method of hydrothermal and d.c. magnetron sputtering. The microstructure and optical properties of the samples were characterized respectively by means of X-ray diffraction (XRD, field-emission scanning electron microscopy (FESEM and UV–vis spectrometer. The results showed that the TiO2 composite nanorod arrays possess the nature of high surface area for more dye molecule absorption and the strong light scattering effects. The dye sensitized solar cells (DSSCs based on TiO2 composite nanorod arrays exhibited a 80% improvement in the overall energy conversion efficiency compared with the pure TiO2 nanorod arrays photoanode.

  5. Controllable hydrothermal synthesis of rutile TiO2 hollow nanorod arrays on TiCl4 pretreated Ti foil for DSSC application

    International Nuclear Information System (INIS)

    Xi, Min; Zhang, Yulan; Long, Lizhen; Li, Xinjun

    2014-01-01

    Rutile TiO 2 nanorod arrays (TNRs) were achieved by hydrothermal process on TiCl 4 pretreated Ti foil. Subsequently, TNRs were hydrothermally etched in HCl solution to form hollow TiO 2 nanorod arrays (H-TNRs). The TiCl 4 pretreatment plays key roles in enhancement of Ti foil corrosion resistance ability and crystal nucleation introduction for TNRs growth. TNRs with desired morphology can be obtained by controlling TiCl 4 concentration and the amount of tetrabutyl titanate (TTB) accordingly. TNRs with the length of ∼1.5 μm and diameter of ∼200 nm, obtained on 0.15 M TiCl 4 pretreated Ti foil with 0.6 mL TTB, exhibits relatively higher photocurrent. The increased pore volume of the H-TNRs has contributed to the increased surface area which is benefit for Dye-Sensitized Solar Cells (DSSC) application. And the 180 °C-H-TNRs photoanode obtained from the 0.15-TiCl 4 -TNRs sample demonstrated 128.9% enhancement of photoelectric efficiency of DSSC compared to that of the original TNR photoanode. - Graphical abstract: Rutile hollow TiO 2 nanorod array photoanode obtained from original TiO 2 nanorod array photoanode by hydrothermal etching demonstrates enhanced photoelectric efficiency of DSSC. - Highlights: • TiO 2 nanorods are prepared via hydrothermal process on TiCl 4 -pretreated Ti foil. • Hollow TiO 2 nanorods are obtained by hydrothermal etching of TiO 2 nanorods. • TiCl 4 pretreatment plays a key role in protecting Ti foil from chemical corrosion. • Hollow TiO 2 nanorods photoanode shows enhanced photoelectric efficiency for DSSC

  6. Annealing Effect on Photovoltaic Performance of CdSe Quantum-Dots-Sensitized TiO2 Nanorod Solar Cells

    Directory of Open Access Journals (Sweden)

    Yitan Li

    2012-01-01

    Full Text Available Large area rutile TiO2 nanorod arrays were grown on F:SnO2 (FTO conductive glass using a hydrothermal method at low temperature. CdSe quantum dots (QDs were deposited onto single-crystalline TiO2 nanorod arrays by a chemical bath deposition (CBD method to make a photoelectrode. The solar cell was assembled using a CdSe-TiO2 nanostructure as the photoanode and polysulfide solution as the electrolyte. The annealing effect on optical and photovoltaic properties of CdSe quantum-dots-sensitized TiO2 nanorod solar cells was studied systematically. A significant change of the morphology and a regular red shift of band gap of CdSe nanoparticles were observed after annealing treatment. At the same time, an improved photovoltaic performance was obtained for quantum-dots-sensitized solar cell using the annealed CdSe-TiO2 nanostructure electrode. The power conversion efficiency improved from 0.59% to 1.45% as a consequence of the annealing effect. This improvement can be explained by considering the changes in the morphology, the crystalline quality, and the optical properties caused by annealing treatment.

  7. Highly piezoelectric BaTiO3 nanorod bundle arrays using epitaxially grown TiO2 nanomaterials

    Science.gov (United States)

    Jang, Seon-Min; Yang, Su Chul

    2018-06-01

    Low-dimensional piezoelectric nanostructures such as nanoparticles, nanotubes, nanowires, nanoribbons and nanosheets have been developed for potential applications as energy harvesters, tunable sensors, functional transducers and low-power actuators. In this study, lead-free BaTiO 3 nanorod bundle arrays (NBA) with highly piezoelectric properties were successfully synthesized on fluorine-doped tin oxide (FTO) substrate via a two-step process consisting of TiO2 epitaxial growth and BaTiO3 conversion. Through the TiO2 epitaxial growth on FTO substrate, (001) oriented TiO2 nanostructures formed vertically-aligned NBA with a bundle diameter of 80 nm and an aspect ratio of six. In particular, chemical etching of the TiO2 NBA was conducted to enlarge the surface area for effective Ba2+ ion diffusion during the perovskite conversion process from TiO2 to BaTiO3. The final structure of perovskite BaTiO3 NBA was found to exhibit a feasible piezoelectric response of 3.56 nm with a clear phase change of 180° from the single BaTiO3 bundle, by point piezoelectric forced microscopy (PFM) analysis. Consequently, highly piezoelectric NBA could be a promising nanostructure for various nanoscale electronic devices.

  8. Highly piezoelectric BaTiO3 nanorod bundle arrays using epitaxially grown TiO2 nanomaterials.

    Science.gov (United States)

    Jang, Seon-Min; Yang, Su Chul

    2018-06-08

    Low-dimensional piezoelectric nanostructures such as nanoparticles, nanotubes, nanowires, nanoribbons and nanosheets have been developed for potential applications as energy harvesters, tunable sensors, functional transducers and low-power actuators. In this study, lead-free BaTiO 3 nanorod bundle arrays (NBA) with highly piezoelectric properties were successfully synthesized on fluorine-doped tin oxide (FTO) substrate via a two-step process consisting of TiO 2 epitaxial growth and BaTiO 3 conversion. Through the TiO 2 epitaxial growth on FTO substrate, (001) oriented TiO 2 nanostructures formed vertically-aligned NBA with a bundle diameter of 80 nm and an aspect ratio of six. In particular, chemical etching of the TiO 2 NBA was conducted to enlarge the surface area for effective Ba 2+ ion diffusion during the perovskite conversion process from TiO 2 to BaTiO 3 . The final structure of perovskite BaTiO 3 NBA was found to exhibit a feasible piezoelectric response of 3.56 nm with a clear phase change of 180° from the single BaTiO 3 bundle, by point piezoelectric forced microscopy (PFM) analysis. Consequently, highly piezoelectric NBA could be a promising nanostructure for various nanoscale electronic devices.

  9. Enhanced visible light photocatalytic properties of Fe-doped TiO2 nanorod clusters and monodispersed nanoparticles

    International Nuclear Information System (INIS)

    Liu, Y.; Wei, J.H.; Xiong, R.; Pan, C.X.; Shi, J.

    2011-01-01

    In order to get photocatalysts with desired morphologies and enhanced visible light responses, the Fe-doped TiO 2 nanorod clusters and monodispersed nanoparticles were prepared by modified hydrothermal and solvothermal method, respectively. The microstructures and morphologies of TiO 2 crystals can be controlled by restraining the hydrolytic reaction rates. The Fe-doped photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis absorption spectroscopy (UV-vis), N 2 adsorption-desorption measurement (BET), and photoluminescence spectroscopy (PL). The refinements of the microstructures and morphologies result in the enhancement of the specific surface areas. The Fe 3+ -dopants in TiO 2 lattices not only lead to the significantly extending of the optical responses from UV to visible region but also diminish the recombination rates of the electrons and holes. The photocatalytic activities were evaluated by photocatalytic decomposition of formaldehyde in air under visible light illumination. Compared with P25 (TiO 2 ) and N-doped TiO 2 nanoparticles, the Fe-doped photocatalysts show high photocatalytic activities under visible light.

  10. Fabrication of TiO_2 nanorod assembly grafted rGO (rGO@TiO_2-NR) hybridized flake-like photocatalyst

    International Nuclear Information System (INIS)

    Lv, Kangle; Fang, Shun; Si, Lingling; Xia, Yang; Ho, Wingkei; Li, Mei

    2017-01-01

    Highlights: • TiO_2 nanorod assembly grafted with GO hybrid was successfully fabricated. • TiO_2 nanorods can reduce the aggregation of TiO_2 nanoparticles on graphene. • This unique structure facilitates the injection of electron from TiO_2 to graphene. - Abstract: To efficiently separate the photo-generated electron–hole pairs of TiO_2 hybrid, anatase TiO_2 nanorod assembly grafted reduced graphene oxides (rGO@TiO_2-NR) hybrid was successfully fabricated using potassium titanium oxalate (PTO) and graphene oxides (GO) as starting materials and diethylene glycol (DEG) as reductant. The effect of GO content on the structure and photocatalytic activity of rGO@TiO_2-NR composite was systematically studied. Results show that, in the absence of GO, only TiO_2 microsphere assembly is obtained from TiO_2 nanorods. The presence of GO results in the formation of a flake-like TiO_2-nanorod-assembled grafted rGO hybrid. The photocatalytic activity of rGO@TiO_2-NR composite increases first and then decreases with increase in the amount of GO from 0 wt.% to 10 wt.%. The hybridized S4 sample prepared with 4 wt.% GO possesses the highest photocatalytic activity with a constant rate of 0.039 min"−"1 in the photocataytic degradation of Brilliant X-3B dye (X3B); this sample was enhanced more than three times when compared with pure TiO_2 sample (0.012 min"−"1). The enhanced photocatalytic activity of the rGO@TiO_2-NR hybrid was attributed to the strong interaction between TiO_2 nanorods and rGO. The unique hierarchical structure of 1D nanorod assembly TiO_2–rGO flakes facilitates the injection and transfer of photo-generated electrons from TiO_2 to graphene, thus retarding the recombination of electron–hole pairs and enhancing the photocatalytic activity. The enlarged BET surface areas, not only increasing the number of active sites, but also facilitating the adsorption of the dye, and improved light-harvesting ability also contribute to the enhanced photoreactivity

  11. Simply synthesized TiO2 nanorods as an effective scattering layer for quantum dot sensitized solar cells

    International Nuclear Information System (INIS)

    Samadpour, Mahmoud; Zad, Azam Iraji; Molaei, Mehdi

    2014-01-01

    TiO 2 nanorod layers are synthesized by simple chemical oxidation of Ti substrates. Diffuse reflectance spectroscopy measurements show effective light scattering properties originating from nanorods with length scales on the order of one micron. The films are sensitized with CdSe quantum dots (QDs) by successive ionic layer adsorption and reaction (SILAR) and integrated as a photoanode in quantum dot sensitized solar cells (QDSCs). Incorporating nanorods in photoanode structures provided 4- to 8-fold enhancement in light scattering, which leads to a high power conversion efficiency, 3.03% (V oc = 497 mV, J sc = 11.32 mA/cm 2 , FF = 0.54), in optimized structures. High efficiency can be obtained just by tuning the photoanode structure without further treatments, which will make this system a promising nanostructure for efficient quantum dot sensitized solar cells. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  12. Fabrication of TiO2-Reduced Graphene Oxide Nanorod Composition Spreads Using Combinatorial Hydrothermal Synthesis and Their Photocatalytic and Photoelectrochemical Applications.

    Science.gov (United States)

    Lu, Wen-Chung; Tseng, Li-Chun; Chang, Kao-Shuo

    2017-09-11

    This study is the first to employ combinatorial hydrothermal synthesis and facile spin-coating technology to fabricate TiO 2 -reduced graphene oxide (rGO) nanorod composition spreads. The features of this study are (1) the development of a self-designed spin-coating wedge, (2) the systemic investigation of the structure-property relationship of the system, (3) the high-throughput screening of the optimal ratio from a wide range of compositions for photocatalytic and photoelectrochemical (PEC) applications, and (4) the effective coupling between the density gradient TiO 2 nanorod array and the thickness gradient rGO. The formation of rGO in the fabricated TiO 2 -rGO sample was monitored through Fourier transform infrared spectrometry. Transmission electron microscopy images also suggested that the TiO 2 nanorod surfaces were covered with a thin layer of amorphous rGO. The rutile TiO 2 plane evolution along the composition variation was verified through X-ray diffraction. 7% TiO 2 -93% rGO on the nanorod composition spread exhibited the most promising photocatalytic ability; the corresponding photodegradation kinetics, denoted by the photodegradation rate constant (k), was determined to be approximately 12.7 × 10 -3 min -1 . The excellent performance was attributed to the effective coupling between the TiO 2 and rGO, which improved the charge carrier transport, thus inhibiting electron-hole pair recombination. A cycling test implied that 7% TiO 2 -93% rGO is a reliable photocatalyst. A photoluminescence spectroscopy study also supported the superior photocatalytic ability of the sample, which was attributed to its markedly poorer recombination behavior. In addition, without further treatment, the sample exhibited excellent PEC stability; the photocurrent density was more than three times higher than that exhibited by the density gradient TiO 2 nanorods.

  13. Improving the Efficiency of Dye-Sensitized Solar Cells by Growing Longer ZnO Nanorods on TiO2 Photoanodes

    Directory of Open Access Journals (Sweden)

    Bao-gai Zhai

    2017-01-01

    Full Text Available By increasing the temperature of hydrothermal reactions from 70 to 100°C, vertically aligned ZnO nanorods were grown on the TiO2 thin film in the photoanode of dye-sensitized solar cells (DSSCs as the blocking layer to reduce the electron back recombinations at the TiO2/electrolyte interfaces. The length effects of ZnO nanorods on the photovoltaic performances of TiO2 based DSSCs were investigated by means of scanning electron microscope, X-ray diffractometer, photoluminescence spectrophotometer, and the photocurrent-voltage measurement. Under the illumination of 100 mW/cm2, the power conversion efficiency of DSSC with ZnO nanorods decorated TiO2 thin film as its photoanode can be increased nearly fourfold from 0.27% to 1.30% as the length of ZnO nanorods increases from 300 to 1600 nm. The enhanced efficiency of DSSC with ZnO nanorods decorated TiO2 thin film as the photoanode can be attributed to the larger surface area and the lower defect density in longer ZnO nanorods, which are in favor of more dye adsorption and more efficient transport in the photoanode.

  14. Enhanced supercapacitor performance using hierarchical TiO2 nanorod/Co(OH)2 nanowall array electrodes

    International Nuclear Information System (INIS)

    Ramadoss, Ananthakumar; Kim, Sang Jae

    2014-01-01

    Graphical abstract: - Highlights: • TiO 2 /Co(OH) 2 hierarchical nanostructure was prepared by a combination of hydrothermal and cathodic electrodeposition method. • Hierarchical nanostructure electrode exhibited a maximum capacitance of 274.3 mF cm −2 at a scan rate of 5 mV s −1 . • Combination of Co(OH) 2 nanowall with TiO 2 NR into a single system enhanced the electrochemical behavior of supercapacitor electrode. - Abstract: We report novel hierarchical TiO 2 nanorod (NR)/porous Co(OH) 2 nanowall array electrodes for high-performance supercapacitors fabricated using a two-step process that involves hydrothermal and electrodeposition techniques. Field-emission scanning electron microscope images reveal a bilayer structure consisting of TiO 2 NR arrays with porous Co(OH) 2 nanowalls. Compared with the bare TiO 2 NRs, the hierarchical TiO 2 NRs/Co(OH) 2 electrodes showed improved pseudocapacitive performance in a 2-M KOH electrolyte solution, exhibiting an areal specific capacitance of 274.3 mF cm −2 at a scan rate of 5 mV s −1 . The electrodes exhibited good stability, retaining 82.5% of the initial capacitance after 4000 cycles. The good pseudocapacitive performance of the hierarchical nanostructures is mainly due to the porous structure, which provides fast ion and electron transfer, a large surface area, short ion diffusion paths, and a favourable volume change during the cycling process

  15. Rapid thermal melted TiO2 nano-particles into ZnO nano-rod and its application for dye sensitized solar cells

    International Nuclear Information System (INIS)

    Chao, Ching-Hsun; Chang, Chi-Lung; Chan, Chien-Hung; Lien, Shui-Yang; Weng, Ko-Wei; Yao, Kuo-Shan

    2010-01-01

    TiO 2 nano-particles with an anchored ZnO nano-rod structure were synthesized using the hydrothermal method to grow ZnO nano-rods and coated TiO 2 nano-particles on ZnO nano-rods using the rapid thermal annealing method on ITO conducting glass pre-coated with nano porous TiO 2 film. The XRD study showed that there was little difference in crystal composition for various types of TiO 2 nano-particles anchored to ZnO nano-rods. The as-prepared architecture was characterized using field-emission scanning electron microscopy (FE-SEM). Films with TiO 2 nano-particles anchored to ZnO nano-rods were used as electrode materials to fabricate dye sensitized solar cells (DSSCs). The best solar energy conversion efficiency of 2.397% was obtained by modified electrode material, under AM 1.5 illumination, achieved up to J sc = 15.382 mA/cm 2 , V oc = 0.479 V and fill factor = 32.8%.

  16. Pr3+ doped biphasic TiO2 (rutile-brookite) nanorod arrays grown on activated carbon fibers: Hydrothermal synthesis and photocatalytic properties

    Science.gov (United States)

    Li, Min; Zhang, Xiaomei; Liu, Ying; Yang, Yi

    2018-05-01

    Praseodymium-doped biphasic TiO2 (rutile-brookite) nanorod arrays (Pr-TiO2 NRAs) were successfully prepared via a two-step hydrothermal reaction on activated carbon fibers (ACFs) which pre-coated with TiO2 nanoparticles at first step. The bicrystalline arrays grown on ACFs are primarily constructed by the well-aligned TiO2 nanorods growing along [0 0 1] direction, which were indicated by the results of SEM and XRD. The nanorods are uniform in diameter and length with about 250 nm and 2.5 μm. The composite photocatalyst with high specific surface area and well-aligned nanostructure are beneficial to enhance the adsorption capacity and even help to suppress electron-hole recombination effectively, which consequently revealed much better (2 times) catalytic performance than that of commercially available P25 TiO2 on methylene blue(MB) photodegradation. In addition, the existence of praseodymium in TiO2 gives rise to shift of absorption edge towards long wavelength, which was indicated by the results of UV-vis DRS. Photodegradation results reveal that Pr-doping significantly improves the activity of TiO2, which was 20% higher than that of undoped TiO2 NRAs for the photodegradation of MB in aqueous medium under visible light irradiation. Meanwhile, the doped amount of Pr had a tiny influence on the photocatalytic performance of the composites. In our experiment, 3% Pr-doped molar concentration was proven to be the relatively optimal dopant concentration for the doping of TiO2 NRAs. Moreover, the photocatalyst grown on ACFs substrates is favorable to reuse and photodegradation rate kept on 76% even after 4 times of reuse.

  17. Sn4+-Doped TiO2 Nanorod Array Film with Enhanced Visible Light ...

    Indian Academy of Sciences (India)

    61

    specific surface area of flat film than nano-powder would lead to the decrease of its .... doped TiO2 NAFs were acquired with EDS spectrometer fitted on the microscopy. ... The morphologies of films were obtained by the SEM measurement.

  18. Short-length and high-density TiO2 nanorod arrays for the efficient charge separation interface in perovskite solar cells

    International Nuclear Information System (INIS)

    Xiao, Guannan; Shi, Chengwu; Zhang, Zhengguo; Li, Nannan; Li, Long

    2017-01-01

    The TiO 2 nanorod arrays with the length of 70 nm, the diameter of 20 nm, and the areal density of 1000 µm −2 were firstly prepared by the hydrothermal method using the aqueous grown solution of 38 mM titanium isopropoxide and 6 M hydrochloric acid at 170 °C for 60 min. Over-500 nm-thickness CH 3 NH 3 PbI 3−x Br x absorber layers were successfully obtained by sequential deposition routes using 1.7 M PbI 2 ·DMSO complex precursor solution and 0.465 M isopropanol solution of the methylammonium halide mixture with the molar ratio of CH 3 NH 3 I/CH 3 NH 3 Br=85/15. The perovskite solar cells based on the TiO 2 nanorod array and 560 nm-thickness CH 3 NH 3 PbI 3−x Br x absorber layer exhibited the best photoelectric conversion efficiency (PCE) of 15.93%, while the corresponding planar perovskite solar cells without the TiO 2 nanorod array and with 530 nm-thickness CH 3 NH 3 PbI 3−x Br x absorber layer gave the best PCE of 12.82% at the relative humidity of 50–54%. - Graphical abstract: The TiO 2 nanorod arrays with the length of 70 nm, the diameter of 20 nm, and the areal density of 1000 µm −2 were prepared by the hydrothermal method using the aqueous grown solution of 38 mM titanium isopropoxide and 6 M hydrochloric acid at 170 °C for 60 min. The optimal annealing temperature of TiO 2 nanorod arrays was 450 °C. The perovskite solar cells based on the TiO 2 nanorod array and 560 nm-thickness CH 3 NH 3 PbI 3−x Br x absorber layer exhibited the best photoelectric conversion efficiency (PCE) of 15.93% and the average PCE of 13.41±2.52%, while the corresponding planar perovskite solar cells without the TiO 2 nanorod array and with 530 nm-thickness CH 3 NH 3 PbI 3−x Br x absorber layer gave the best PCE of 12.82% and the average PCE of 10.54±2.28% at the relative humidity of 50–54%. - Highlights: • Preparation of TiO 2 nanorod array with length of 70 nm and density of 1000 µm −2 . • Influence of annealing temperatures on the -OH content of Ti

  19. Optimization of charge transfer and transport processes at the CdSe quantum dots/TiO2 nanorod interface by TiO2 interlayer passivation

    International Nuclear Information System (INIS)

    Jaramillo-Quintero, O A; Rincon, M E; Triana, M A

    2017-01-01

    Surface trap states hinder charge transfer and transport properties in TiO 2 nanorods (NRs), limiting its application on optoelectronic devices. Here, we study the interfacial processes between rutile TiO 2 NR and CdSe quantum dots (QDs) using TiO 2 interlayer passivation treatments. Anatase or rutile TiO 2 thin layers were deposited on an NR surface by two wet-chemical deposition treatments. Reduced interfacial charge recombination between NRs and CdSe QDs was observed by electrochemical impedance spectroscopy with the introduction of TiO 2 thin film interlayers compared to bare TiO 2 NRs. These results can be ascribed to in-gap trap state passivation of the TiO 2 NR surface, which led to an increase in open circuit voltage. Moreover, the rutile thin layer was more efficient than anatase to promote a higher photo-excited electron transfer from CdSe QDs to TiO 2 NRs due to a large driving force for charge injection, as confirmed by surface photovoltage spectroscopy. (paper)

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

    Science.gov (United States)

    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.

  1. Fabrication of TiO2 nanorod assembly grafted rGO (rGO@TiO2-NR) hybridized flake-like photocatalyst

    Science.gov (United States)

    Lv, Kangle; Fang, Shun; Si, Lingling; Xia, Yang; Ho, Wingkei; Li, Mei

    2017-01-01

    To efficiently separate the photo-generated electron-hole pairs of TiO2 hybrid, anatase TiO2 nanorod assembly grafted reduced graphene oxides (rGO@TiO2-NR) hybrid was successfully fabricated using potassium titanium oxalate (PTO) and graphene oxides (GO) as starting materials and diethylene glycol (DEG) as reductant. The effect of GO content on the structure and photocatalytic activity of rGO@TiO2-NR composite was systematically studied. Results show that, in the absence of GO, only TiO2 microsphere assembly is obtained from TiO2 nanorods. The presence of GO results in the formation of a flake-like TiO2-nanorod-assembled grafted rGO hybrid. The photocatalytic activity of rGO@TiO2-NR composite increases first and then decreases with increase in the amount of GO from 0 wt.% to 10 wt.%. The hybridized S4 sample prepared with 4 wt.% GO possesses the highest photocatalytic activity with a constant rate of 0.039 min-1 in the photocataytic degradation of Brilliant X-3B dye (X3B); this sample was enhanced more than three times when compared with pure TiO2 sample (0.012 min-1). The enhanced photocatalytic activity of the rGO@TiO2-NR hybrid was attributed to the strong interaction between TiO2 nanorods and rGO. The unique hierarchical structure of 1D nanorod assembly TiO2-rGO flakes facilitates the injection and transfer of photo-generated electrons from TiO2 to graphene, thus retarding the recombination of electron-hole pairs and enhancing the photocatalytic activity. The enlarged BET surface areas, not only increasing the number of active sites, but also facilitating the adsorption of the dye, and improved light-harvesting ability also contribute to the enhanced photoreactivity of rGO@TiO2-NR hybrid.

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

    KAUST Repository

    Teo, Gladys Y.

    2014-10-01

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

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

    KAUST Repository

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

    2014-01-01

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

  4. The role of annealing temperature variation on ZnO nanorods array deposited on TiO2 seed layer

    Science.gov (United States)

    Asib, N. A. M.; Aadila, A.; Afaah, A. N.; Rusop, M.; Khusaimi, Z.

    2018-05-01

    Seed layer of Titanium dioxide (TiO2) by sol-gel spin coating technique were coated on glass substrate to grow Zinc oxide nanorods (ZNR) by solution-immersion method. The fabricated ZNR were annealed at various temperatures ranged from 400 to 600° C. FESEM images revealed that smaller ZNR were densely grown at optimum temperature of 450 and 500°C. Meanwhile, for all samples a dominant (0 0 2) diffraction peak of ZNR recorded by XRD patterns was at 34.4° which corresponding to hexagonal ZNR with a wurtzite structure. UV-Vis absorbance spectra showed the maximum absorption properties at UV region were detected at 450 and 500°C. The samples also showed high absorbance values at visible region.

  5. Effect of growth time on the structure, morphology and optical properties of hydrothermally synthesized TiO2 nanorod thin films

    Science.gov (United States)

    Mohapatra, A. K.; Nayak, J.

    2018-05-01

    Titanium dioxide (TiO2) nanorod thin films were deposited on fluorine doped tin oxide coated glass substrates by a single step rapid hydrothermal process. The concentration of the precursor, the temperature of the reaction mixture were optimized in order to enhance the rate of deposition. Unlike the previously reported hydrothermal treatment for 24 - 48 h, the deposition of well aligned titanium dioxide nanorods was achieved in a short time such as 3 - 8 h. The crystal structure of the films were investigated by X-rays diffraction. The morphology of the nanorod films were studied with scanning electron microscopy. The optical properties were studied by photoluminescence spectroscopy.

  6. TiO2 nanorod arrays functionalized with In2S3 shell layer by a low-cost route for solar energy conversion

    International Nuclear Information System (INIS)

    Gan Xiaoyan; Li Xiaomin; Gao Xiangdong; Qiu Jijun; Zhuge Fuwei

    2011-01-01

    We report the fabrication and characterization of a TiO 2 -In 2 S 3 core-shell nanorod array structure for application of semiconductor-sensitized solar cells. Hydrothermally synthesized TiO 2 nanorod arrays on FTO glass substrates are functionalized with a uniform In 2 S 3 shell layer by using the successive ion layer adsorption and reaction (SILAR) method. This low-cost technique promotes a uniform deposition of In 2 S 3 nanoshells on the surface of TiO 2 nanorods, thus forming an intact interface between the In 2 S 3 shell and TiO 2 core. Results show that the thickness of In 2 S 3 shell layers as well as the visible light absorption threshold can be effectively controlled by varying the coating cycles during the SILAR process. The best reproducible performance of the sandwich solar cell using the TiO 2 -In 2 S 3 core-shell nanorod arrays as photoelectrodes was obtained after 30 SILAR cycles, exhibiting a short-circuit current (I sc ) of 2.40 mA cm -2 , an open-circuit voltage (V oc ) of 0.56 V, a fill factor (ff) of 0.40 and a conversion efficiency (η) of 0.54%, respectively. These results demonstrate a feasible and controllable route towards In 2 S 3 coating on a highly structured substrate and a proof of concept that such TiO 2 -In 2 S 3 core-shell architectures are novel and promising photoelectrodes in nanostructured solar cells.

  7. CdS Nanoparticle-Modified α-Fe2O3/TiO2 Nanorod Array Photoanode for Efficient Photoelectrochemical Water Oxidation.

    Science.gov (United States)

    Yin, Ruiyang; Liu, Mingyang; Tang, Rui; Yin, Longwei

    2017-09-02

    In this work, we demonstrate a facile successive ionic layer adsorption and reaction process accompanied by hydrothermal method to synthesize CdS nanoparticle-modified α-Fe 2 O 3 /TiO 2 nanorod array for efficient photoelectrochemical (PEC) water oxidation. By integrating CdS/α-Fe 2 O 3 /TiO 2 ternary system, light absorption ability of the photoanode can be effectively improved with an obviously broadened optical-response to visible light region, greatly facilitates the separation of photogenerated carriers, giving rise to the enhancement of PEC water oxidation performance. Importantly, for the designed abnormal type-II heterostructure between Fe 2 O 3 /TiO 2 , the conduction band position of Fe 2 O 3 is higher than that of TiO 2 , the photogenerated electrons from Fe 2 O 3 will rapidly recombine with the photogenerated holes from TiO 2 , thus leads to an efficient separation of photogenerated electrons from Fe 2 O 3 /holes from TiO 2 at the Fe 2 O 3 /TiO 2 interface, greatly improving the separation efficiency of photogenerated holes within Fe 2 O 3 and enhances the photogenerated electron injection efficiency in TiO 2 . Working as the photoanodes of PEC water oxidation, CdS/α-Fe 2 O 3 /TiO 2 heterostucture electrode exhibits improved photocurrent density of 0.62 mA cm - 2 at 1.23 V vs. reversible hydrogen electrode (RHE) in alkaline electrolyte, with an obviously negatively shifted onset potential of 80 mV. This work provides promising methods to enhance the PEC water oxidation performance of the TiO 2 -based heterostructure photoanodes.

  8. Adsorption of carbon dioxide on TEPA-modified TiO_2/titanate composite nano-rods

    International Nuclear Information System (INIS)

    Kapica-Kozar, Joanna; Michalkiewicz, Beata; Wrobel, Rafal J.; Mozia, Sylwia; Pirog, Ewa; Usiak-Nejman, Ewelina K.; Serafin, Jaroslaw; Morawski, Antoni W.; Narkiewicz, Urszula

    2017-01-01

    A titanate-TiO_2 composite was obtained through hydrothermal treatment of TiO_2 in KOH solution. The presence of a titanate phase was confirmed by X-ray diffraction (XRD), whereas scanning electron microscopy (SEM) measurements showed the porous nano-rod structure of the material. The obtained nano-rods were treated with tetra-ethylene-pentamine (TEPA). Such synthesized sorbents were applied for CO_2 removal. The CO_2 capacity under a pressure of 1 bar and at 80 C was 0.47, 0.34, and 3.11 mmol.g"-"1 for the starting TiO_2, the titanate-TiO_2 composite and the TEPA-titanate-TiO_2 composite (27.4 wt% of TEPA), respectively. The experimental isotherms of CO_2 were analysed using the Langmuir, Freundlich, Sips, Toth, Unilan, Redlich-Peterson, Radke-Prausnitz, Dubinin-Radushkevich, Temkin and Pyzhev, and Jovanovich models. The error sums of squares (SSR) function was used to test the fit of the models. The analysis revealed that the Sips isotherm is the best-fitting model for the CO_2 adsorption on the starting TiO_2, whereas the Freundlich equation should be used to describe the CO_2 adsorption isotherm on the titanate-TiO_2 composite. The CO_2 adsorption on the TEPA-modified sorbents was proposed to be described using the Sips isotherm for physical sorption and the modified Sips model for chemical sorption. The calculated isosteric heat of adsorption was found to be E46 kJ mol"-"1, which is about two times higher than the heat of CO_2 absorption in liquid TEPA reported in the literature (i.e. E85 kJ.mol"-"1). Therefore, it was concluded that the TEPA-titanate-TiO_2 composite is an attractive alternative for liquid amines due to the lower energy of regeneration in the sorption-desorption process. The material was proved to be stable during multiple sorption-desorption cycles. Moreover, its thermal stability up to 150 C was confirmed by thermogravimetric analysis (TGA). All these features make it a promising alternative for sorbents based on liquid amines. (authors)

  9. TiO2 nanocrystals decorated Z-schemed core-shell CdS-CdO nanorod arrays as high efficiency anodes for photoelectrochemical hydrogen generation.

    Science.gov (United States)

    Li, Chia-Hsun; Hsu, Chan-Wei; Lu, Shih-Yuan

    2018-07-01

    TiO 2 nanocrystals decorated core-shell CdS-CdO nanorod arrays, TiO 2 @CdO/CdS NR, were fabricated as high efficiency anodes for photoelctrochemical hydrogen generation. The novel sandwich heterostructure was constructed from first growth of CdS nanorod arrays on a fluorine doped tin oxide (FTO) substrate with a hydrothermal process, followed by in situ generation of CdO thin films of single digit nanometers from the CdS nanorod surfaces through thermal oxidation, and final decoration of TiO 2 nanocrystals of 10-20 nm via a successive ionic layer absorption and reaction process. The core-shell CdS-CdO heterostructure possesses a Z-scheme band structure to enhance interfacial charge transfer, facilitating effective charge separation to suppress electron-hole recombination within CdS for much improved current density generation. The final decoration of TiO 2 nanocrystals passivates surface defects and trap states of CdO, further suppressing surface charge recombination for even higher photovoltaic conversion efficiencies. The photoelectrochemical performances of the plain CdS nanorod array were significantly improved with the formation of the sandwich heterostructure, achieving a photo current density of 3.2 mA/cm 2 at 1.23 V (vs. RHE), a 141% improvement over the plain CdS nanorod array and a 32% improvement over the CdO/CdS nanorod array. Copyright © 2018 Elsevier Inc. All rights reserved.

  10. Tunable photovoltaic performance of preferentially oriented rutile TiO2 nanorod photoanodes based dye sensitized solar cells with quasi-state electrolyte.

    Science.gov (United States)

    T C, Sabari Girisun; C, Jeganathan; N, Pavithra; Anandan, Sambandam

    2017-12-20

    Photoanodes made of highly oriented TiO2 nanorod arrays with different aspect ratios were synthesized via one-step hydrothermal technique. Preferentially oriented single crystalline rutile TiO2 was confirmed by the single peak in XRD pattern (2θ=63o, (0 0 2)). FESEM image evidence the growth of an array of nanorods having different geometry with respect to reaction time and solution refreshment rate. The length, diameter and aspect ratio of the nanorods increased with reaction time as 4 hours (1.98 μm, 121 nm, 15.32), 8 hours (4 μm, 185 nm, 22.70), 12 hours (5.6 μm, 242 nm, 27.24) and 16 hours (8 μm, 254 nm, 38.02) respectively. Unlike conventional Dye-Sensitized Solar Cell (DSSC) with a liquid electrolyte, DSSC were fabricated here using 1D rutile TiO2 nanorods based photoanodes, N719 dye and quasi-state electrolyte. The charge transport properties were investigated from current-voltage curves and fitted using one-diode model. Interestingly photovoltaic performance of DSSCs increased exponentially with the length of the nanorod and is attributed to the higher surface to volume ratio, more dye anchoring, and channelized electron transport. Higher photovoltaic performance (Jsc=5.99 mA/cm2, Voc=750 mV, η=3.08%) was observed with photoanodes (16 hours) made of densely packed longest TiO2 nanorods (8 µm, 254 nm). © 2017 IOP Publishing Ltd.

  11. Role of Ag2S coupling on enhancing the visible-light-induced catalytic property of TiO2 nanorod arrays

    Science.gov (United States)

    Li, Zhengcao; Xiong, Shan; Wang, Guojing; Xie, Zheng; Zhang, Zhengjun

    2016-01-01

    In order to obtain a better photocatalytic performance under visible light, Ag2S-coupled TiO2 nanorod arrays (NRAs) were prepared through the electron beam deposition with glancing angle deposition (GLAD) technique, annealing in air, followed by the successive ionic layer absorption and reaction (SILAR) method. The properties of the photoelectrochemical and photocatalytic degradation of methyl orange (MO) were thus conducted. The presence of Ag2S on TiO2 NRAs was observed to have a significant improvement on the response to visible light. It’s resulted from that Ag2S coupling can improve the short circuit photocurrent density and enhance the photocatalytic activity remarkably.

  12. Photodegradation of phenol by N-Doped TiO2 anatase/rutile nanorods assembled microsphere under UV and visible light irradiation

    International Nuclear Information System (INIS)

    Mohamed, Mohamad Azuwa; Salleh, W.N.W.; Jaafar, Juhana; Ismail, A.F.; Nor, Nor Azureen Mohamad

    2015-01-01

    N-doped TiO 2 anatase/rutile nanorods assembled microspheres were successfully synthesized via a simple and direct sol–gel method containing titanium-n-butoxide Ti(OBu) 4 as a precursor material, nitric acid as a catalyst, and isopropanol as a solvent. By manipulating calcination temperature, the photocatalyst consisting of different phase compositions of anatase and rutile was obtained. The prepared TiO 2 nanoparticles were characterized by means of x-ray diffraction (XRD), field emission scanning microscope (FESEM), atomic force microscopy (AFM), Brunauer–Emmett–Teller (BET) analysis, UV–Vis–NIR spectroscopy, and fourier transform infrared (FTIR). The results from UV–Vis–NIR spectroscopy and FTIR revealed the direct incorporation of nitrogen in TiO 2 lattice since visible absorption capability was observed at 400–600 nm. XPS study indicated the incorporation of nitrogen as dopant in TiO 2 at binding energies of 396.8, 397.5, 398.7, 399.8, and 401 eV. Calcination temperature was observed to have a great influence on the photocatalytic activity of the TiO 2 nanorods. The photocatalytic activity of the prepared mixed phase of anatase/rutile TiO 2 nanoparticles was measured by photodegradation phenol in an aqueous solution under UV and visible irradiations. N-doped TiO 2 anatase/rutile nanorods assembled microsphere (consists of 38.3% anatase and 61.7% rutile) that was prepared at 400 °C exhibited the highest photocatalytic activity after irradiated under visible and UV light for 540 min. The high performance of photocatalyst materials could be obtained by adopting a judicious combination of anatase/rutile prepared at optimum calcination conditions. - Highlights: • Synthesis of N-Doped TiO 2 Anatase/Rutile Nanorods via simple preparation method. • Direct incorporation of HNO 3 as the nitrogen dopant source. • The photocatalytic properties were studied upon UV and visible light irradiation. • The optimum calcination temperature is 400 °C for

  13. Controlled Assembly of Nanorod TiO2 Crystals via a Sintering Process: Photoanode Properties in Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Saeid Vafaei

    2017-01-01

    Full Text Available We present for the first time a synthetic method of obtaining 1D TiO2 nanorods with sintering methods using bundle-shaped 3D rutile TiO2 particles (3D BR-TiO2 with the dimensions of around 100 nm. The purpose of this research is (i to control crystallization of the mixture of two kinds of TiO2 semiconductor nanocrystals, that is, 3D BR-TiO2 and spherical anatase TiO2 (SA-TiO2 on FTO substrate via sintering process and (ii to establish a new method to create photoanodes in dye-sensitized solar cells (DSSCs. In addition, we focus on the preparation of low-cost and environmentally friendly titania electrode by adopting the “water-based” nanofluids. Our results provide useful guidance on how to improve the photovoltaic performance by reshaping the numerous 3D TiO2 particles to 1D TiO2-based electrodes with sintering technique.

  14. Photo-electrochemical properties of graphene wrapped hierarchically branched nanostructures obtained through hydrothermally transformed TiO2 nanotubes

    Science.gov (United States)

    Rambabu, Y.; Jaiswal, Manu; Roy, Somnath C.

    2017-10-01

    Hierarchically structured nanomaterials play an important role in both light absorption and separation of photo-generated charges. In the present study, hierarchically branched TiO2 nanostructures (HB-MLNTs) are obtained through hydrothermal transformation of electrochemically anodized TiO2 multi-leg nanotubes (MLNT) arrays. Photo-anodes based on HB-MLNTs demonstrated 5 fold increase in applied bias to photo-conversion efficiency (%ABPE) over that of TiO2 MLNTs without branches. Further, such nanostructures are wrapped with reduced graphene oxide (rGO) films to enhance the charge separation, which resulted in ∼6.5 times enhancement in %ABPE over that of bare MLNTs. We estimated charge transport (η tr) and charge transfer (η ct) efficiencies by analyzing the photo-current data. The ultra-fine nano branches grown on the MLNTs are effective in increasing light absorption through multiple scattering and improving charge transport/transfer efficiencies by enlarging semiconductor/electrolyte interface area. The charge transfer resistance, interfacial capacitance and electron decay time have been estimated through electrochemical impedance measurements which correlate with the results obtained from photocurrent measurements.

  15. Solid-State Dewetting of Gold Aggregates/Islands on TiO2 Nanorod Structures Grown by Oblique Angle Deposition.

    Science.gov (United States)

    Liu, Shizhao; Plawsky, Joel L

    2017-12-12

    A composite film made of a stable gold nanoparticle (NP) array with well-controlled separation and size atop a TiO 2 nanorod film was fabricated via the oblique angle deposition (OAD) technique. The fabrication of the NP array is based on controlled, Rayleigh-instability-induced, solid-state dewetting of as-deposited gold aggregates on the TiO 2 nanorods. It was found that the initial spacing between as-deposited gold aggregates along the vapor flux direction should be greater than the TiO 2 interrod spacing created by 80° OAD to control dewetting and produce NP arrays. A numerical investigation of the process was conducted using a phase-field modeling approach. Simulation results showed that coalescence between neighboring gold aggregates is likely to have caused the uncontrolled dewetting in the 80° deposition, and this could be circumvented if the initial spacing between gold aggregates is larger than a critical value s min . We also found that TiO 2 nanorod tips affect dewetting dynamics differently than planar TiO 2 . The topology of the tips can induce contact line pinning and an increase in the contact angle along the vapor flux direction to the supported gold aggregates. These two effects are beneficial for the fabrication of monodisperse NPs based on Rayleigh-instability-governed self-assembly of materials, as they help to circumvent the undesired coalescence and facilitate the instability growth on the supported material. The findings uncover the application potential of OAD as a new method to fabricate structured films as template substrates to mediate dewetting. The reported composite films would have uses in optical coatings and photocatalytic systems, taking advantage of their ability to combine plasmonic nanostructures within a nanostructured dielectric film.

  16. Surfactant-free bio-synthesised Tio2 nanorods from Turbinaria conoides-a study on photocatalytic and anti-bacterial activity

    Science.gov (United States)

    Subhapriya, S.; Gomathipriya, P.

    2018-06-01

    In this study, Titania nanorods were synthesised from aqueous extract of Turbinaria conoides (brown seaweeds) (TiO2NRs-TC) under surfactant free medium. The photocatalytic activity of the synthesised nanorods was tested towards the photocatalytic decolourization using simulated dye wastewater containing Navy Blue HER (NBHER). The synthesised Titania nanorods were characterized by using x-ray diffraction (XRD), UV–visible spectroscopy (UV–vis), Scanning Electron Microscopy (SEM), Energy Dispersive Spectrophotometer (EDS) and Transmission Electron Microscopy (TEM). XRD pattern confirms the anatase phase formation and HR-SEM micrograph shows the presence of rod like structure with the size of about 50 nm. TEM analysis proves the rod like structure with a size of 45–50 nm which was in agreement with the XRD analysis and HR-SEM images. EDS and XDS confirmed the formation of Titania nanoparticles. The formation of TiO2NRs-TC has a beneficial influence on the dye Navy blue HER photodegradation. TiO2-TC nano rods also show superior photocatalytic ability in hydrogen generation (2.1 mmol/h‑1g‑1). The antibacterial activity of the synthesised nanoparticles was examined using disc diffusion method which showed diverse susceptibility of microorganisms to the Titania nanoparticles.

  17. Films of brookite TiO2 nanorods/nanoparticles deposited by matrix-assisted pulsed laser evaporation as NO2 gas-sensing layers

    Science.gov (United States)

    Caricato, A. P.; Buonsanti, R.; Catalano, M.; Cesaria, M.; Cozzoli, P. D.; Luches, A.; Manera, M. G.; Martino, M.; Taurino, A.; Rella, R.

    2011-09-01

    Titanium dioxide (TiO2) nanorods in the brookite phase, with average dimensions of 3-4 nm × 20-50 nm, were synthesized by a wet-chemical aminolysis route and used as precursors for thin films that were deposited by the matrix-assisted pulsed laser evaporation (MAPLE) technique. A nanorod solution in toluene (0.016 wt% TiO2) was frozen at the liquid-nitrogen temperature and irradiated with a KrF excimer laser at a fluence of 350 mJ/cm2 and repetition rate of 10 Hz. Single-crystal Si wafers, silica slides, carbon-coated Cu grids and alumina interdigitated slabs were used as substrates to allow performing different characterizations. Films fabricated with 6000 laser pulses had an average thickness of ˜150 nm, and a complete coverage of the selected substrate as achieved. High-resolution scanning and transmission electron microscopy investigations evidenced the formation of quite rough films incorporating individually distinguishable TiO2 nanorods and crystalline spherical nanoparticles with an average diameter of ˜13 nm. Spectrophotometric analysis showed high transparency through the UV-Vis spectral range. Promising resistive sensing responses to 1 ppm of NO2 mixed in dry air were obtained.

  18. Design and construction of hierarchical TiO2 nanorod arrays by combining layer-by-layer and hydrothermal crystallization techniques for electrochromic application

    Science.gov (United States)

    Chen, Yongbo; Li, Xiaomin; Bi, Zhijie; He, Xiaoli; Li, Guanjie; Xu, Xiaoke; Gao, Xiangdong

    2018-05-01

    The hierarchical TiO2 (H-TiO2) nanorod arrays (NRAs) composed of single-crystalline nanorods and nanocrystals were finely designed and successfully constructed for electrochromic (EC) application. By combining layer-by-layer (LBL) method and hydrothermal crystallization technique, the superfine nanocrystals (5-7 nm), which can provide abundant active sites and facilitate ion insertion/extraction during EC reactions, were uniformly and conformally assembled on the surface of single-crystalline TiO2 (SC-TiO2) NRAs. The as-formed H-TiO2 NRAs integrate the advantages of one-dimensional NRAs with fast kinetics and superfine nanocrystals with high ion capacity, showing highly enhanced EC performance. Large optical contrast (40.3%), shorter coloring/bleaching time (22/4 s), high coloration efficiency (11.2 cm2 C-1), and excellent cycling stability can be achieved in H-TiO2 NRAs, superior to the pristine SC-TiO2 NRAs and nanocrystalline TiO2 films. This work provides a feasible and well-designed strategy to explore high-performance materials for EC application.

  19. Photocatalytic activity of Ti3+ self-doped dark TiO2 ultrafine nanorods, grey SiO2 nanotwin crystalline, and their composite under visible light

    Science.gov (United States)

    Zhang, Renhui; Yang, Yingchang; Leng, Senlin; Wang, Qing

    2018-04-01

    Efficient electron-holes separation is of crucial importance for the improvement of photocatalytic activity for photocatalytic reaction. In this work, dark TiO2 (D-TiO2) nanorods, grey SiO2 (G-SiO2) and D-TiO2/G-SiO2 composite with surface defects are synthesized. We report that the efficiency of photo-generated electrons and holes separation is well enhanced by introducing G-SiO2 into D-TiO2 lattice. Using first-principles method, we find that surface defects (O or Si vacancy) can be conducive to improving the optical absorption under visible-light region. Combination of the experimental results, for D-TiO2/G-SiO2 composite, the surface defects of TiO2 nanocrystallines can significantly improve the photocatalytic efficiency.

  20. Hollow TiO2@Co9S8 Core-Branch Arrays as Bifunctional Electrocatalysts for Efficient Oxygen/Hydrogen Production.

    Science.gov (United States)

    Deng, Shengjue; Zhong, Yu; Zeng, Yinxiang; Wang, Yadong; Wang, Xiuli; Lu, Xihong; Xia, Xinhui; Tu, Jiangping

    2018-03-01

    Designing ever more efficient and cost-effective bifunctional electrocatalysts for oxygen/hydrogen evolution reactions (OER/HER) is greatly vital and challenging. Here, a new type of binder-free hollow TiO 2 @Co 9 S 8 core-branch arrays is developed as highly active OER and HER electrocatalysts for stable overall water splitting. Hollow core-branch arrays of TiO 2 @Co 9 S 8 are readily realized by the rational combination of crosslinked Co 9 S 8 nanoflakes on TiO 2 core via a facile and powerful sulfurization strategy. Arising from larger active surface area, richer/shorter transfer channels for ions/electrons, and reinforced structural stability, the as-obtained TiO 2 @Co 9 S 8 core-branch arrays show noticeable exceptional electrocatalytic performance, with low overpotentials of 240 and 139 mV at 10 mA cm -2 as well as low Tafel slopes of 55 and 65 mV Dec -1 for OER and HER in alkaline medium, respectively. Impressively, the electrolysis cell based on the TiO 2 @Co 9 S 8 arrays as both cathode and anode exhibits a remarkably low water splitting voltage of 1.56 V at 10 mA cm -2 and long-term durability with no decay after 10 d. The versatile fabrication protocol and smart branch-core design provide a new way to construct other advanced metal sulfides for energy conversion and storage.

  1. Heterostructured TiO2/NiTiO3 Nanorod Arrays for Inorganic Sensitized Solar Cells with Significantly Enhanced Photovoltaic Performance and Stability.

    Science.gov (United States)

    Li, Yue-Ying; Wang, Jian-Gan; Sun, Huan-Huan; Wei, Bingqing

    2018-04-11

    Organic dyes used in the conventional dye-sensitized solar cells (DSSCs) suffer from poor light stability and high cost. In this work, we demonstrate a new inorganic sensitized solar cell based on ordered one-dimensional semiconductor nanorod arrays of TiO 2 /NiTiO 3 (NTO) heterostructures prepared via a facile two-step hydrothermal approach. The semiconductor heterostructure arrays are highly desirable and promising for DSSCs because of their direct charge transport capability and slow charge recombination rate. The low-cost NTO inorganic semiconductor possesses an appropriate band gap that matches well with TiO 2 , which behaves like a "dye" to enable efficient light harvesting and fast electron-hole separation. The solar cells constructed by the ordered TiO 2 /NTO heterostructure photoanodes show a significantly improved power conversion efficiency, high fill factor, and more promising, outstanding life stability. The present work will open up an avenue to design heterostructured inorganics for high-performance solar cells.

  2. Combination of short-length TiO_2 nanorod arrays and compact PbS quantum-dot thin films for efficient solid-state quantum-dot-sensitized solar cells

    International Nuclear Information System (INIS)

    Zhang, Zhengguo; Shi, Chengwu; Chen, Junjun; Xiao, Guannan; Li, Long

    2017-01-01

    Graphical abstract: The TiO_2 nanorod array with the length of 600 nm, the diameter of 20 nm, the areal density of 500 μm"−"2 was successfully prepared. The compact PbS quantum-dot thin film was firstly obtained on the TiO_2 nanorod array by spin-coating-assisted successive ionic layer absorption and reaction with using 1,2-ethanedithiol. The photoelectric conversion efficiency (PCE) of the compact PbS quantum-dot thin film sensitized solar cells achieved 4.10% using spiro-OMeTAD as a hole transporting layer, while the PCE of the PbS quantum-dot sensitized solar cells was only 0.54%. - Highlights: • Preparation of TiO_2 nanorod arrays with the length of 600 nm, diameter of 20 nm. • The compact PbS QD thin film and short-length TiO_2 nanorod array were combined. • EDT addition improved PbS nanoparticle coverage and photovoltaic performance. • The compact PbS QD thin film sensitized solar cell achieved the PCE of 4.10%. - Abstract: Considering the balance of the hole diffusion length and the loading quantity of quantum-dots, the rutile TiO_2 nanorod array with the length of 600 nm, the diameter of 20 nm, and the areal density of 500 μm"−"2 is successfully prepared by the hydrothermal method using the aqueous grown solution of 38 mM titanium isopropoxide and 6 M hydrochloric acid at 170 °C for 105 min. The compact PbS quantum-dot thin film on the TiO_2 nanorod array is firstly obtained by the spin-coating-assisted successive ionic layer absorption and reaction with using 1,2-ethanedithiol (EDT). The result reveals that the strong interaction between lead and EDT is very important to control the crystallite size of PbS quantum-dots and obtain the compact PbS quantum-dot thin film on the TiO_2 nanorod array. The all solid-state sensitized solar cell with the combination of the short-length, high-density TiO_2 nanorod array and the compact PbS quantum-dot thin film achieves the photoelectric conversion efficiency of 4.10%, along with an open

  3. TiO2 Nanorod Arrays Based Self-Powered UV Photodetector: Heterojunction with NiO Nanoflakes and Enhanced UV Photoresponse.

    Science.gov (United States)

    Gao, Yanyan; Xu, Jianping; Shi, Shaobo; Dong, Hong; Cheng, Yahui; Wei, Chengtai; Zhang, Xiaosong; Yin, Shougen; Li, Lan

    2018-04-04

    The self-powered ultraviolet photodetectors (UV PDs) have attracted increasing attention due to their potential applications without consuming any external power. It is important to obtain the high-performance self-powered UV PDs by a simple method for the practical application. Herein, TiO 2 nanorod arrays (NRs) were synthesized by hydrothermal method, which were integrated with p-type NiO nanoflakes to realize a high performance pn heterojunction for the efficient UV photodetection. TiO x thin film can improve the morphological and carrier transport properties of TiO 2 NRs and decrease the surface and defect states, resulting in the enhanced photocurrent of the devices. NiO/TiO 2 nanostructural heterojunctions show excellent rectifying characteristics (rectification ratio of 2.52 × 10 4 and 1.45 × 10 5 for NiO/TiO 2 NRs and NiO/TiO 2 NRs/TiO x , respectively) with a very low reverse saturation current. The PDs based on the heterojunctions exhibit good spectral selectivity, high photoresponsivity, and fast response and recovery speeds without external applied bias under the weak light radiation. The devices demonstrate good stability and repeatability under UV light radiation. The self-powered performance could be attributed to the proper built-in electric field of the heterojunction. TiO 2 NRs and NiO nanoflakes construct the well-aligned energy-band structure. The enhanced responsivity and detectivity for the devices with TiO x thin films is related to the increased interfacial charge separation efficiency, reduced carrier recombination, and relatively good electron transport of TiO 2 NRs.

  4. Tunable photovoltaic performance of preferentially oriented rutile TiO2 nanorod photoanode based dye sensitized solar cells with quasi-state electrolyte.

    Science.gov (United States)

    Girisun, T C Sabari; Jeganathan, C; Pavithra, N; Anandan, S

    2018-01-23

    Photoanodes made of highly oriented TiO 2 nanorod (NR) arrays with different aspect ratios were synthesized via a one-step hydrothermal technique. Preferentially oriented single crystalline rutile TiO 2 was confirmed by the single peak in an XRD pattern (2θ = 63°, (0 0 2)). FESEM images evidenced the growth of an array of NRss having different geometries with respect to reaction time and solution refreshment rate. The length, diameter and aspect ratio of the NRs increased with reaction time as 4 h (1.98 μm, 121 nm, 15.32), 8 h (4 μm, 185 nm, 22.70), 12 h (5.6 μm, 242 nm, 27.24) and 16 h (8 μm, 254 nm, 38.02), respectively. Unlike a conventional dye-sensitized solar cell (DSSC) with a liquid electrolyte, DSSCs were fabricated here using one-dimensional rutile TiO 2 NR based photoanodes, N719 dye and a quasi-state electrolyte. The charge transport properties were investigated using current-voltage curves and fitted using the one-diode model. Interestingly the photovoltaic performance of the DSSCs increased exponentially with the length of the NR and was attributed to a higher surface to volume ratio, more dye anchoring, and channelized electron transport. The higher photovoltaic performance (J sc  = 5.99 mA cm -2 , V oc  = 750 mV, η = 3.08%) was observed with photoanodes (16 h) made with the longer, densely packed TiO 2 NRs (8 μm, 254 nm).

  5. Solid state perovskite solar modules by vacuum-vapor assisted sequential deposition on Nd:YVO_4 laser patterned rutile TiO_2 nanorods

    International Nuclear Information System (INIS)

    Fakharuddin, Azhar; Wali, Qamar; Rauf, Muhammad; Jose, Rajan; Palma, Alessandro L; Giacomo, Francesco Di; Casaluci, Simone; Matteocci, Fabio; Carlo, Aldo Di; Brown, Thomas M

    2015-01-01

    The past few years have witnessed remarkable progress in solution-processed methylammonium lead halide (CH_3NH_3PbX_3, X = halide) perovskite solar cells (PSCs) with reported photoconversion efficiency (η) exceeding 20% in laboratory-scale devices and reaching up to 13% in their large area perovskite solar modules (PSMs). These devices mostly employ mesoporous TiO_2 nanoparticles (NPs) as an electron transport layer (ETL) which provides a scaffold on which the perovskite semiconductor can grow. However, limitations exist which are due to trap-limited electron transport and non-complete pore filling. Herein, we have employed TiO_2 nanorods (NRs), a material offering a two-fold higher electronic mobility and higher pore-filing compared to their particle analogues, as an ETL. A crucial issue in NRs’ patterning over substrates is resolved by using precise Nd:YVO_4 laser ablation, and a champion device with η ∼ 8.1% is reported via a simple and low cost vacuum-vapor assisted sequential processing (V-VASP) of a CH_3NH_3PbI_3 film. Our experiments showed a successful demonstration of NRs-based PSMs via the V-VASP technique which can be applied to fabricate large area modules with a pin-hole free, smooth and dense perovskite layer which is required to build high efficiency devices. (paper)

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

    Science.gov (United States)

    Boda, Muzaffar Ahmad; Ashraf Shah, Mohammad

    2018-06-01

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

  7. Efficient one-pot synthesis of Ag nanoparticles loaded on N-doped multiphase TiO2 hollow nanorod arrays with enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    Wu Min; Yang Beifang; Lv Yan; Fu Zhengping; Xu Jiao; Guo Ting; Zhao Yongxun

    2010-01-01

    The simultaneous Ag loaded and N-doped TiO 2 hollow nanorod arrays with various contents of silver (Ag/N-THNAs) were successfully synthesized on glass substrates by one-pot liquid phase deposition (LPD) method using ZnO nanorod arrays as template. The catalysts were characterized by Raman spectrum, field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscope (HRTEM), ultraviolet-vis (UV-vis) absorption spectrum and X-ray photoelectron spectroscopy (XPS). The results suggest that AgNO 3 additive in the precursor solutions not only can promote the anatase-to-rutile phase transition, but also influence the amount of N doping in the samples. The photocatalytic activity of all the samples was evaluated by photodegradation of methylene blue (MB) in aqueous solution. The sample exhibited the highest photocatalytic activity under UV light illumination when the AgNO 3 concentration in the precursor solution was 0.03 M, due to Ag nanoparticles acting as electron sinks; When the AgNO 3 concentration was 0.07 M, the sample performed best under visible light illumination, attributed to the synergetic effects of Ag loading, N doping, and the multiphase structure (anatase/rutile).

  8. Construction of AgBr nano-cakes decorated Ti3+ self-doped TiO2 nanorods/nanosheets photoelectrode and its enhanced visible light driven photocatalytic and photoelectrochemical properties

    Science.gov (United States)

    Deng, Xiaoyong; Zhang, Huixuan; Guo, Ruonan; Cheng, Xiuwen; Cheng, Qingfeng

    2018-05-01

    In the study, AgBr nano-cakes decorated Ti3+ self-doped TiO2 nanorods/nanosheets (AgBr-Ti3+/TiO2 NRs/NSs) photoelectrode with enhanced visible light driven photocatalytic (PC) and photoelectrochemical (PECH) performance has been successfully fabricated by hydrothermal reaction, followed by sodium borohydride reduction and then successive ionic layer adsorption and reaction (SILAR) treatment. Afterwards, series of characterizations were conducted to study the physicochemical properties of AgBr-Ti3+/TiO2 NRs/NSs photoelectrode. Results indicated that AgBr nano-cakes with sizes varying from 110 to 180 nm were uniformly decorated on the surface of Ti3+/TiO2 NRs/NSs to form AgBr-Ti3+/TiO2 NRs/NSs photoelectrode. Moreover, PC activity of AgBr-Ti3+/TiO2 NRs/NSs photoelectrode was measured by degradation of methylene blue (MB). It was found that AgBr-Ti3+/TiO2 NRs/NSs photoelectrode exhibited higher PC activity (98.7%) than that of other samples within 150 min visible light illumination, owing to the enhancement of visible light harvesting and effective separation of photoproduced charges. Thus, AgBr nano-cakes and Ti3+ exerted a huge influence on the PC and PECH properties of AgBr-Ti3+/TiO2 NRs/NSs photoelectrode. Furthermore, the possible enhanced visible light driven PC mechanism of AgBr-Ti3+/TiO2 NRs/NSs was proposed and confirmed.

  9. Graphene oxide hydrogel as a restricted-area nanoreactor for synthesis of 3D graphene-supported ultrafine TiO2 nanorod nanocomposites for high-rate lithium-ion battery anodes

    Science.gov (United States)

    Cheng, Jianli; Gu, Guifang; Ni, Wei; Guan, Qun; Li, Yinchuan; Wang, Bin

    2017-07-01

    Three-dimensional graphene-supported TiO2 nanorod nanocomposites (3D GS-TNR) are prepared using graphene oxide hydrogel as a restricted-area nanoreactor in the hydrothermal process, in which well-distributed TiO2 nanorods with a width of approximately 5 nm and length of 30 nm are conformally embedded in the 3D interconnected graphene network. The 3D graphene oxide not only works as a restricted-area nanoreactor to constrain the size, distribution and morphology of the TiO2; it also work as a highly interconnected conducting network to facilitate electrochemical reactions and maintain good structural integration when the nanocomposites are used as anode materials in lithium-ion batteries. Benefiting from the nanostructure, the 3D GS-TNR nanocomposites show high capacity and excellent long-term cycling capability at high current rates. The 3D GS-TNR composites deliver a high initial charge capacity of 280 mAh g-1 at 0.2 C and maintain a reversible capacity of 115 mAh g-1, with a capacity retention of 83% at 20 C after 1000 cycles. Meanwhile, compared with that of previously reported TiO2-based materials, the 3D GS-TNR nanocomposites show much better performance, including higher capacity, better rate capability and long-term cycling stability.

  10. DC sputtering assisted nano-branched core–shell TiO2/ZnO electrodes for application in dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Zhang, Zengming; Hu, Yong; Qin, Fuyu; Ding, Yutian

    2016-01-01

    Highlights: • An effective method of combining chemical growth and physical decoration to investigate the effect of the energy barrier layer on the efficiency of DSSCs were presented. • High surface area photo-anodes can be achieved through fine-tuning material growth processes. • The branched composite structure shows a set of advantages in electronic transportation, dye adsorption and energy barrier. - Graphical abstract: Schematic diagram of nano-branched core–shell TiO 2 /ZnO electrodes and SEM images of the photoanodes at each step. - Abstract: TiO 2 /ZnO core–shell photo-anodes with a large surface area were synthesised by a combination of chemical growth and direct current (DC) magnetron sputtering (MS). The use of these combined methods for the advancement of dye-sensitized solar cells (DSSCs) was discussed. An understanding of the morphology and structure of this core–shell material was obtained from the use of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that the thickness of the ZnO nanoshells (as assessed by using TEM), prepared by MS, has a significant effect on improvements in the conversion efficiency. The conversion efficiency can be greatly improved from 0.06% to 0.72% by optimising different experimental conditions, such as ZnO nanoshell MS time and chemical bath deposition time. The enhanced efficiency may be attributed to the emergence of a ZnO energy barrier and the improvement of the photo-anode surface area.

  11. One-step synthesis of CdTe branched nanowires and nanorod arrays

    International Nuclear Information System (INIS)

    Hou Junwei; Yang Xiuchun; Lv Xiaoyi; Peng Dengfeng; Huang Min; Wang Qingyao

    2011-01-01

    Single crystalline CdTe branched nanowires and well-aligned nanorod arrays were simultaneously synthesized by a simple chemical vapor deposition (CVD) technique. X-ray diffraction (XRD), scanning electronic microscopy (SEM), transmission electronic microscopy (TEM) and selected area electronic diffraction (SAED) were used to study the crystalline structure, composition and morphology of different samples. Vapor-liquid-solid (VLS) and vapor-solid (VS) processes were proposed for the formation of the CdTe branched nanowires and nanorod arrays, respectively. As-grown CdTe nanorod arrays show a strong red emission band centered at about 620 nm, which can be well fitted by two Gaussian curves centered at 610 nm and 635 nm, respectively.

  12. Improvement of light harvesting and device performance of dye-sensitized solar cells using rod-like nanocrystal TiO2 overlay coating on TiO2 nanoparticle working electrode

    International Nuclear Information System (INIS)

    Liu, Xueyang; Fang, Jian; Gao, Mei; Wang, Hongxia; Yang, Weidong; Lin, Tong

    2015-01-01

    Novel TiO 2 single crystalline nanorods were synthesized by electrospinning and hydrothermal treatment. The role of the TiO 2 nanorods on TiO 2 nanoparticle electrode in improvement of light harvesting and photovoltaic properties of dye-sensitized solar cells (DSSCs) was examined. Although the TiO 2 nanorods had lower dye loading than TiO 2 nanoparticle, they showed higher light utilization behaviour. Electron transfer in TiO 2 nanorods received less resistance than that in TiO 2 nanoparticle aggregation. By just applying a thin layer of TiO 2 nanorods on TiO 2 nanoparticle working electrode, the DSSC device light harvesting ability and energy conversion efficiency were improved significantly. The thickness of the nanorod layer in the working electrode played an important role in determining the photovoltaic property of DSSCs. An energy conversion efficiency as high as 6.6% was found on a DSSC device with the working electrode consisting of a 12 μm think TiO 2 nanoparticle layer covered with 3 μm thick TiO 2 nanorods. The results obtained from this study may benefit further design of highly efficient DSSCs. - Highlights: • Single crystalline TiO 2 nanorods were prepared for DSSC application. • TiO 2 nanorods show effective light scattering performance. • TiO 2 nanorods have higher electron transfer efficiency than TiO 2 nanoparticles. • TiO 2 nanorods on TiO 2 nanoparticle electrode improve DSSC efficiency

  13. Study on activities of vanadium (IV/V) doped TiO2(R) nanorods induced by UV and visible light

    International Nuclear Information System (INIS)

    Li, Li; Liu Chunyan; Liu Yun

    2009-01-01

    Vanadium (IV/V) doped rutile TiO 2 naonorods had been successfully synthesized through a single step hydrothermal method. The photocatalyst was characterized by transmission electron microscopy (TEM), selected area electron diffraction (SAED), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), UV-vis diffusive reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The results showed that the doping of V ions had significant influence on the band gap energy and the surface state of TiO 2 . The photo-activities of the new catalysts were investigated under ultraviolet (UV) and visible light. The UV-photocatalytic activity of the as-prepared catalysts was hardly influenced by doping V ions; while under visible light, the samples with 1 wt% and 0.1 wt% V exhibited enhanced activity to the oxidation of methylene blue (MB) and the reduction of Cr (VI), respectively

  14. Controlled synthesis of ZnO branched nanorod arrays by hierarchical solution growth and application in dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Fang Xiaoming; Peng Lihua; Shang Xiaoying; Zhang Zhengguo

    2011-01-01

    We demonstrate the controlled synthesis of ZnO branched nanorod arrays on fluorine-doped SnO 2 -coated glass substrates by the hierarchical solution growth method. In the secondary growth, the concentration of Zn(NO 3 ) 2 /hexamethylenetetramine plays an important role in controlling the morphology of the branched nanorod arrays, besides that of diaminopropane used as a structure-directing agent to induce the growth of branches. The population density and morphology of the branched nanorod arrays depend on those of the nanorod arrays obtained from the primary growth, which can be modulated though the concentration of Zn(NO 3 ) 2 /hexamethylenetetramine in the primary growth solution. The dye-sensitized ZnO branched nanorod arrays exhibit much stronger optical absorption as compared with its corresponding primary nanorod arrays, suggesting that the addition of the branches improves light harvesting. The dye-sensitized solar cell based on the optimized ZnO branched nanorod array reaches a conversion efficiency of 1.66% under the light radiation of 1000 W/m 2 . The branched nanorod arrays can also be applied in other application fields of ZnO.

  15. Facile synthesis of highly branched jacks-like ZnO nanorods and their applications in dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Sudhagar, P. [Center for Next Generation Dye-sensitized Solar Cells, WCU Program Department of Energy Engineering, Hanyang University, Seongdong-gu, Seoul- 133 791 (Korea, Republic of); Kumar, R. Saravana [R and D Department of Physics, Kongunadu Arts and Science College, Coimbatore 641 029, Tamilnadu (India); Jung, June Hyuk; Cho, Woohyung [Center for Next Generation Dye-sensitized Solar Cells, WCU Program Department of Energy Engineering, Hanyang University, Seongdong-gu, Seoul- 133 791 (Korea, Republic of); Sathyamoorthy, R. [R and D Department of Physics, Kongunadu Arts and Science College, Coimbatore 641 029, Tamilnadu (India); Won, Jongok [Department of Chemistry, Sejong University, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Kang, Yong Soo, E-mail: kangys@hanyang.ac.kr [Center for Next Generation Dye-sensitized Solar Cells, WCU Program Department of Energy Engineering, Hanyang University, Seongdong-gu, Seoul- 133 791 (Korea, Republic of)

    2011-09-15

    Graphical abstract: -- Abstract: Highly branched, jacks-like ZnO nanorods architecture were explored as a photoanode in dye-sensitized solar cells, and their photovoltaic performance was compared with that of branch-free ZnO nanorods photoanodes. The highly branched network and large pores of the jacks-like ZnO nanorods electrodes enhances the charge transport, and electrolyte penetration. Thus, the jacks-like ZnO nanorods DSSCs render a higher conversion efficiency of {eta} = 1.82% (V{sub oc} = 0.59 V, J{sub sc} = 5.52 mA cm{sup -2}) than that of the branch-free ZnO nanorods electrodes ({eta} = 1.08%, V{sub oc} = 0.49 V, J{sub sc} = 4.02 mA cm{sup -2}). The incident photon-to-current conversion efficiency measurements reveal that the jacks-like ZnO nanorods DSSCs exhibit higher internal quantum efficiency ({approx}59.1%) than do the branch-free ZnO nanorods DSSC ({approx}52.5%). The charge transfer resistances at the ZnO/dye/electrolyte interfaces investigated using electrochemical impedance spectroscopy showed that the jacks-like ZnO nanorods DSSC had high charge transfer resistance and a slightly longer electron lifetime, thus improving the solar-cell performance.

  16. Facile synthesis of highly branched jacks-like ZnO nanorods and their applications in dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Sudhagar, P.; Kumar, R. Saravana; Jung, June Hyuk; Cho, Woohyung; Sathyamoorthy, R.; Won, Jongok; Kang, Yong Soo

    2011-01-01

    Graphical abstract: -- Abstract: Highly branched, jacks-like ZnO nanorods architecture were explored as a photoanode in dye-sensitized solar cells, and their photovoltaic performance was compared with that of branch-free ZnO nanorods photoanodes. The highly branched network and large pores of the jacks-like ZnO nanorods electrodes enhances the charge transport, and electrolyte penetration. Thus, the jacks-like ZnO nanorods DSSCs render a higher conversion efficiency of η = 1.82% (V oc = 0.59 V, J sc = 5.52 mA cm -2 ) than that of the branch-free ZnO nanorods electrodes (η = 1.08%, V oc = 0.49 V, J sc = 4.02 mA cm -2 ). The incident photon-to-current conversion efficiency measurements reveal that the jacks-like ZnO nanorods DSSCs exhibit higher internal quantum efficiency (∼59.1%) than do the branch-free ZnO nanorods DSSC (∼52.5%). The charge transfer resistances at the ZnO/dye/electrolyte interfaces investigated using electrochemical impedance spectroscopy showed that the jacks-like ZnO nanorods DSSC had high charge transfer resistance and a slightly longer electron lifetime, thus improving the solar-cell performance.

  17. Photoelectrocatalytic activity of a hydrothermally grown branched Zno nanorod-array electrode for paracetamol degradation.

    Science.gov (United States)

    Lin, Chin Jung; Liao, Shu-Jun; Kao, Li-Cheng; Liou, Sofia Ya Hsuan

    2015-06-30

    Hierarchical branched ZnO nanorod (B-ZnR) arrays as an electrode for efficient photoelectrocatalytic degradation of paracetamol were grown on fluorine-doped tin oxide substrates using a solution route. The morphologic and structural studies show the ZnO trunks are single-crystalline hexagonal wurtzite ZnO with a [0001] growth direction and are densely covered by c-axis-oriented ZnO branches. The obvious enhancement in photocurrent response of the B-ZnR electrode was obtained than that in the ZnO nanoparticle (ZnO NP) electrode. For the photoelectrocatalytic degradation of paracetamol in 20 h, the conversion fraction of the drug increased from 32% over ZnO NP electrode to 62% over B-ZnR arrays with about 3-fold increase in initial reaction rate. The light intensity-dependent photoelectrocatalytic experiment indicated that the superior performance over the B-ZnR electrode was mainly ascribed to the increased specific surface area without significantly sacrificing the charge transport and pollutant diffusion efficiencies. Two aromatic intermediate compounds were observed and eventually converted into harmless carboxylic acids and ammonia. Hierarchical tree-like ZnO arrays can be considered effective alternatives to improve photoelectro degradation rates without the need for expensive additives. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Nanofabrication and characterization of ZnO nanorod arrays and branched microrods by aqueous solution route and rapid thermal processing

    International Nuclear Information System (INIS)

    Lupan, Oleg; Chow, Lee; Chai, Guangyu; Roldan, Beatriz; Naitabdi, Ahmed; Schulte, Alfons; Heinrich, Helge

    2007-01-01

    This paper presents an inexpensive and fast fabrication method for one-dimensional (1D) ZnO nanorod arrays and branched two-dimensional (2D), three-dimensional (3D) - nanoarchitectures. Our synthesis technique includes the use of an aqueous solution route and post-growth rapid thermal annealing. It permits rapid and controlled growth of ZnO nanorod arrays of 1D - rods, 2D - crosses, and 3D - tetrapods without the use of templates or seeds. The obtained ZnO nanorods are uniformly distributed on the surface of Si substrates and individual or branched nano/microrods can be easily transferred to other substrates. Process parameters such as concentration, temperature and time, type of substrate and the reactor design are critical for the formation of nanorod arrays with thin diameter and transferable nanoarchitectures. X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, transmission electron microscopy and Micro-Raman spectroscopy have been used to characterize the samples

  19. A thick hierarchical rutile TiO2 nanomaterial with multilayered structure

    International Nuclear Information System (INIS)

    Zhu, Shengli; Xie, Guoqiang; Yang, Xianjin; Cui, Zhenduo

    2013-01-01

    Highlights: ► We synthesized a new rutile TiO 2 nanomaterial with a hierarchical nanostructure. ► The nano architecture structure consist of nanorods and nanoflower arrays. ► The rutile TiO 2 nanomaterial is thick in size (several 10 μm). ► The TiO 2 nanomaterials present a multilayer structure. - Abstract: In the present paper, we synthesized a new type of rutile TiO 2 nanomaterial with a hierarchical nanostructure using a novel method, which combined dealloying process with chemical synthesis. The structure characters were examined using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The rutile TiO 2 nanomaterial is thick in size (several 10 μm). The hierarchical structure of the rutile TiO 2 nanomaterial consists of large quantities nanorods and nanoflower arrays. The nanoflowers consist of serveral nanopetals with diameter of 100–200 nm. The cross section of TiO 2 nanomaterials presents a multilayer structure with the layer thickness of about 3–5 μm. The rutile TiO 2 nanomaterial has high specific surface area. The formation mechanism of the rutile TiO 2 nanomaterial was discussed according to the experimental results. The rutile TiO 2 nanomaterial has potential applications in catalysis, photocatalysis and solar cells

  20. Stability and Electronic Properties of TiO2 Nanostructures With and Without B and N Doping

    DEFF Research Database (Denmark)

    Mowbray, Duncan; Martinez, Jose Ignacio; García Lastra, Juan Maria

    2009-01-01

    We address one of the main challenges to TiO2 photocatalysis, namely band gap narrowing, by combining nanostructural changes with doping. With this aim we compare TiO2’s electronic properties for small 0D clusters, 1D nanorods and nanotubes, 2D layers, and 3D surface and bulk phases using differe...

  1. Quantum dot sensitized solar cell based on TiO2/CdS/Ag2S heterostructure

    Science.gov (United States)

    Pawar, Sachin A.; Patil, Dipali S.; Kim, Jin Hyeok; Patil, Pramod S.; Shin, Jae Cheol

    2017-04-01

    Quantum dot sensitized solar cell (QDSSC) is fabricated based on a stepwise band structure of TiO2/CdS/Ag2S to improve the photoconversion efficiency of TiO2/CdS system by incorporating a low band gap Ag2S QDs. Vertically aligned TiO2 nanorods assembly is prepared by a simple hydrothermal technique. The formation of CdS and Ag2S QDs over TiO2 nanorods assembly as a photoanode is carried out by successive ionic layer adsorption and reaction (SILAR) technique. The synthesized electrode materials are characterized by XRD, XPS, field emission scanning electron microscopy (FE-SEM), Optical, solar cell and electrochemical performances. The results designate that the QDs of CdS and Ag2S have efficiently covered exterior surfaces of TiO2 nanorods assembly. A cautious evaluation between TiO2/CdS and TiO2/CdS/Ag2S sensitized cells tells that CdS and Ag2S synergetically helps to enhance the light harvesting ability. Under AM 1.5G illumination, the photoanodes show an improved power conversion efficiency of 1.87%, in an aqueous polysulfide electrolyte with short-circuit photocurrent density of 7.03 mA cm-2 which is four fold higher than that of a TiO2/CdS system.

  2. Quantum Dot Sensitized Solar Cells Based on TiO2/AgInS2

    Science.gov (United States)

    Pawar, Sachin A.; Jeong, Jae Pil; Patil, Dipali S.; More, Vivek M.; Lee, Rochelle S.; Shin, Jae Cheol; Choi, Won Jun

    2018-05-01

    Quantum dot heterojunctions with type-II band alignment can efficiently separate photogenerated electron-hole pairs and, hence, are useful for solar cell studies. In this study, a quantum dot sensitized solar cell (QDSSC) made of TiO2/AgInS2 is achieved to boost the photoconversion efficiency for the TiO2-based system by varying the AgInS2 layer's thickness. The TiO2 nanorods array film is prepared by using a simple hydrothermal technique. The formation of a AgInS2 QD-sensitized TiO2-nanorod photoelectrode is carried out by successive ionic layer adsorption and reaction (SILAR) technique. The effect of the QD layer on the performance of the solar cell is studied by varying the SILAR cycles of the QD coating. The synthesized electrode materials are characterized by using X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, high resolution transmission electron microscopy and solar cell performances. The results indicate that the nanocrystals have effectively covered the outer surfaces of the TiO2 nanorods. The interfacial structure of quantum dots (QDs)/TiO2 is also investigated, and the growth interface is verified. A careful comparison between TiO2/AgInS2 sensitized cells reveals that the trasfer of electrons and hole proceeds efficiently, the recombination is suppressed for the optimum thickness of the QD layer and light from the entire visible spectrum is utilised. Under AM 1.5G illumination, a high photocurrent of 1.36 mAcm-2 with an improved power conversion efficiency of 0.48% is obtained. The solar cell properties of our photoanodes suggest that the TiO2 nanorod array films co-sensitized by AgInS2 nanoclusters have potential applications in solar cells.

  3. Charge separation in branched TiO{sub 2} nanorod array homojunction aroused by quantum effect for enhanced photocatalytic decomposition of gaseous benzene

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaoxia [State Key Laboratory of Materials and Processing Die & Mould Technology, Nanomaterials and Smart Sensors Research Laboratory, Department of Materials Science and Engineering, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Wuhan 430062 (China); Ni, Qian [State Key Laboratory of Materials and Processing Die & Mould Technology, Nanomaterials and Smart Sensors Research Laboratory, Department of Materials Science and Engineering, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Zeng, Dawen, E-mail: dwzeng@mail.hust.edu.cn [State Key Laboratory of Materials and Processing Die & Mould Technology, Nanomaterials and Smart Sensors Research Laboratory, Department of Materials Science and Engineering, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Wuhan 430062 (China); Liao, Guanglan [State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Xie, Changsheng [State Key Laboratory of Materials and Processing Die & Mould Technology, Nanomaterials and Smart Sensors Research Laboratory, Department of Materials Science and Engineering, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China)

    2016-12-15

    Highlights: • Charge separation in homojunction based on the broadened band gap by quantum effect. • Absolute charge separation by the passivation effect of TiO{sub 2} nanorod. • Long-distance electron transfer behavior in photocatalysis. • Roughed surface for enhanced light harvesting by light trapping effect. - Abstract: As known, the electron transfer behavior in photocatalysis is short-distance transportation, which leads the photo-induced electrons and holes to be localized. The temporarily separated electrons and holes will recombine with each other in the localized region. In this paper, we successfully achieved electron transfer in a homojunction of branched rutile TiO{sub 2} nanorod @nanoparticle core-shell architecture by quantum confinement effect aroused by the nanoparticle, which is proved by the blue-shifting in UV–vis absorption spectrum of the homojunction. Meanwhile, an absolute charge separation is also achieved by the long-distance electron transfer along the single-crystalline rutile TiO{sub 2} nanorod as uninterrupted high-speed electron transfer channel to FTO substrates. Based on the effective charge separation, the photocatalytic decomposition of gaseous benzene by the homojunction is significantly enhanced, yielding 10 times CO{sub 2} than that of the nanorod array. This homojunction interfacial charge separation, aroused by quantum effect, through long-distance transfer along the single-crystalline nanorod gives us inspiration to achieve efficient charge separation with defect-less interfaces, which might can be utilized for real-time environmental abatement and energy generation simultaneously.

  4. Electron microscopy observation of TiO2 nanocrystal evolution in high-temperature atomic layer deposition.

    Science.gov (United States)

    Shi, Jian; Li, Zhaodong; Kvit, Alexander; Krylyuk, Sergiy; Davydov, Albert V; Wang, Xudong

    2013-01-01

    Understanding the evolution of amorphous and crystalline phases during atomic layer deposition (ALD) is essential for creating high quality dielectrics, multifunctional films/coatings, and predictable surface functionalization. Through comprehensive atomistic electron microscopy study of ALD TiO2 nanostructures at designed growth cycles, we revealed the transformation process and sequence of atom arrangement during TiO2 ALD growth. Evolution of TiO2 nanostructures in ALD was found following a path from amorphous layers to amorphous particles to metastable crystallites and ultimately to stable crystalline forms. Such a phase evolution is a manifestation of the Ostwald-Lussac Law, which governs the advent sequence and amount ratio of different phases in high-temperature TiO2 ALD nanostructures. The amorphous-crystalline mixture also enables a unique anisotropic crystal growth behavior at high temperature forming TiO2 nanorods via the principle of vapor-phase oriented attachment.

  5. Deliberate Design of TiO2 Nanostructures towards Superior Photovoltaic Cells.

    Science.gov (United States)

    Sun, Ziqi; Liao, Ting; Sheng, Liyuan; Kou, Liangzhi; Kim, Jung Ho; Dou, Shi Xue

    2016-08-01

    TiO2 nanostructures are being sought after as flexibly utilizable building blocks for the fabrication of the mesoporous thin-film photoelectrodes that are the heart of the third-generation photovoltaic devices, such as dye-sensitized solar cells (DSSCs), quantum-dot-sensitized solar cells (QDSSCs), and the recently promoted perovskite-type solar cells. Here, we report deliberate tailoring of TiO2 nanostructures for superior photovoltaic cells. Morphology engineering of TiO2 nanostructures is realized by designing synthetic protocols in which the precursor hydrolysis, crystal growth, and oligomer self-organization are precisely controlled. TiO2 nanostructures in forms varying from isolated nanocubes, nanorods, and cross-linked nanorods to complex hierarchical structures and shape-defined mesoporous micro-/nanostructures were successfully synthesized. The photoanodes made from the shape-defined mesoporous TiO2 microspheres and nanospindles presented superior performances, owing to the well-defined overall shapes and the inner ordered nanochannels, which allow not only a high amount of dye uptake, but also improved visible-light absorption. This study provides a new way to seek an optimal synthetic protocol to meet the required functionality of the nanomaterials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Synthesis, characterization, and photocatalytic activities of Cobalt(II)-Titanium dioxide nanorods, and electrophoretic deposition of Titanium dioxide nanoparticle/nanorod composite films for self-cleaning applications

    Science.gov (United States)

    Kang, Wonjun

    This dissertation consists of two projects. The first project is synthesis, characterization, and photocatalytic activities of Co(II)-TiO2 nanorods. We modified brookite TiO2 nanorods with cobalt(II) ions to design new photocatalysts with visible light absorption. X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) data indicated that the local structure of Co(II)-TiO2 nanorods was shown as tetrahedral and octahedral Co(II) sites at TiO2 nanorod surface. Dimethylglyoxime (DMG) has been used to remove surface Co(II) from Co(II)-TiO2 nanorods to determine single-site Co(II) ions selectively attached to the TiO 2 nanorod surface. We proposed a mechanism that the Co-Co bond of the precursor Co2(CO)8 undergoes heterolysis followed by disproportionation of Co(I) to produce Co(II) and Co(0) precipitate. Finally, the Co(II)-TiO2 nanorods showed greater activity than TiO 2 nanorods in the degradation of 5,8-dihydroxy-1,4-naphthoquinone (DHNQ) dye under visible light irradiation. The second project is electrophoretic deposition (EPD) of TiO2 nanoparticle/nanorod composite films for self-cleaning applications. We developed novel electrolyte system for EPD of TiO2 nanoparticle/nanorod composites for self-cleaning coatings. A mixture of TiO2 powder and TiO2 nanorods was used as EPD suspension in a mixture of THF and acetone. TiO2 nanoparticle/nanorod composite films were fabricated on aluminium substrates via the EPD method, and were characterized by scanning electron microscope (SEM). SEM images showed that TiO2 nanoparticle/nanorod composite films had a uniform pore structure. The hydrophobic properties of surfaces in TiO2 nanoparticle/nanorod composite films were evaluated by water contact angle measurements. It was found that the surfaces of TiO2 nanoparticle/nanorod composite films were hydrophobic with contact angle of 103°. These hydrophobic surfaces are expected to have potential applications for self-cleaning.

  7. Optical and Morphological Properties of ZnO- and TiO2-Derived Nanostructures Synthesized via a Microwave-Assisted Hydrothermal Method

    Directory of Open Access Journals (Sweden)

    Nosipho Moloto

    2012-01-01

    Full Text Available A microwave-assisted hydrothermal method was used to synthesize ZnO and TiO2 nanostructures. The experimental results show that the method resulted in crystalline monodispersed ZnO nanorods that have pointed tips with hexagonal crystal phase. TiO2 nanotubes were also formed with minimum bundles. The mechanism for the formation of the tubes was validated by HRTEM results. The optical properties of both ZnO and TiO2 nanostructures showed characteristics of strong quantum confinement regime. The photoluminescence spectrum of TiO2 nanotubes shows good improvement from previously reported data.

  8. Cellulose nanofiber-templated three-dimension TiO 2 hierarchical nanowire network for photoelectrochemical photoanode

    Science.gov (United States)

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

    2014-01-01

    Three dimensional (3D) nanostructures with extremely large porosity possess a great promise for the development of high-performance energy harvesting storage devices. In this paper, we developed a high-density 3D TiO2 fiber-nanorod (NR) heterostructure for photoelectrochemical (PEC) water splitting. The hierarchical structure was synthesized on a...

  9. Data on the effect of improved TiO2/FTO interface and Ni(OH2 cocatalyst on the photoelectrochemical performances and stability of CdS cased ZnIn2S4/TiO2 heterojunction

    Directory of Open Access Journals (Sweden)

    Mahadeo A. Mahadik

    2018-04-01

    Full Text Available This data article presents the experimental evidences of the effect of TiO2-fluorine doped tin oxide interface annealing and Ni(OH2 cocatalysts on the photoelectrochemical, structural, morphological and optical properties of Ni(OH2/CdS/ZnIn2S4/TiO2 heterojunction. The Raman spectroscopy exhibits the sharp features of the rutile phase of TiO2 and in agreement with the X-ray diffraction data. The band gap energy of the 500 °C sample was found to be 3.12 eV, further it was increased to 3.20, 3.22 eV for samples annealed at 600 and 700 °C respectively. The decrease in the band gap energy at 500 °C related to the oxygen vacancies and was analysed by photoluminescence spectroscopy analysis. The synthesis, characterization methods and other experimental details of TiO2 based heterostructure are also provided. The presence of CdS and ZnIn2S4 coating on surface of TiO2 electrodes providing a high surface area, extended visible absorption and helps to improve the change separation. This data article contains data related to the research article entitled “Highly efficient and stable 3D Ni(OH2/CdS/ZnIn2S4/TiO2 heterojunction under solar light: Effect of an improved TiO2/FTO interface and cocatalyst” (Mahadik et al., 2017 [1]. Keywords: Annealed TiO2 nanorods, CdS/ZnIn2S4/TiO2 heterostructure, Ni(OH2 cocatalyst, TiO2-FTO interface

  10. Solvothermal preparation of micro/nanostructured TiO_2 with enhanced lithium storage capability

    International Nuclear Information System (INIS)

    Li, Jie; Wang, Chao; Zheng, Ping; Zhang, Lei; Chen, Gongxuan; Tang, Chengchun; Wu, Tian

    2017-01-01

    Facile and controllable preparation of TiO_2 is of prime importance to elaborately tailor and then fully exploit its intriguing functionalities in energy storage, catalysis and environmental remediation. Herein, a solvothermal method combined with post annealing is conducted, in which the hydrolysis of tetrabutyl titanate is controlled by the in-situ generated water during solvothermal treatment. By controlling synthetic conditions (i.e. reactant ratio, solvothermal temperature and reaction time), we manage to tailor the morphologies of TiO_2. Specially, three typical structures (nanoparticle, nanoneedle and nanorod) are studied to reveal the growth mechanism and the effects of the synthesis conditions. Nanoneedle-structured TiO_2 shows higher specific capacity and enhanced cycle stability as anode material for lithium ion batteries. - Highlights: • Controllable preparation of nano-TiO_2 is achieved by a solvothermal method. • TiO_2 morphology is tailored by tuning reactant ratio, temperature and duration. • Needle structured TiO_2 shows enhanced lithium storage capability.

  11. Hydrothermal synthesis, characterization, photocatalytic activity and dye-sensitized solar cell performance of mesoporous anatase TiO2 nanopowders

    International Nuclear Information System (INIS)

    Pavasupree, Sorapong; Jitputti, Jaturong; Ngamsinlapasathian, Supachai; Yoshikawa, Susumu

    2008-01-01

    Mesoporous anatase TiO 2 nanopowder was synthesized by hydrothermal method at 130 deg. C for 12 h. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), HRTEM, and Brunauer-Emmett-Teller (BET) surface area. The as-synthesized sample with narrow pore size distribution had average pore diameter about 3-4 nm. The specific BET surface area of the as-synthesized sample was about 193 m 2 /g. Mesoporous anatase TiO 2 nanopowders (prepared by this study) showed higher photocatalytic activity than the nanorods TiO 2 , nanofibers TiO 2 mesoporous TiO 2 , and commercial TiO 2 nanoparticles (P-25, JRC-01, and JRC-03). The solar energy conversion efficiency (η) of the cell using the mesoporous anatase TiO 2 was about 6.30% with the short-circuit current density (Jsc) of 13.28 mA/cm 2 , the open-circuit voltage (Voc) of 0.702 V and the fill factor (ff) of 0.676; while η of the cell using P-25 reached 5.82% with Jsc of 12.74 mA/cm 2 , Voc of 0.704 V and ff of 0.649

  12. Influence of TiO2 Nanoparticles on Growth, Chemical Constituents and Toxicity of Fennel Plant

    International Nuclear Information System (INIS)

    Khater, M.S.; Osman, Y.A.H.

    2015-01-01

    The present work is carried out to evaluate the effect of TiO 2 nanoparticles treatments on fennel (Feoniculum Vulgare Mill) plants. The plants were sprayed with different concentrations of TiO 2 nanoparticles 2, 4 and 6 ppm. In most cases, the tallest plants, the highest number of branches , the highest fruit yield per plant and the highest values of Pigments, Carbohydrates, Sugars nitrogen , phosphorus , potassium were obtained from the treatment of 6 ppm TiO 2 nanoparticles of fennel . Results showed that sprayed fennel plant with concentrations of TiO 2 nanoparticles 0, 2, 4 and 6 ppm is safe and enhanced chlorophyll synthesis and consequently enhanced photosynthesis

  13. 3D Bi2S3/TiO2 cross-linked heterostructure: An efficient strategy to improve charge transport and separation for high photoelectrochemical performance

    Science.gov (United States)

    Han, Minmin; Jia, Junhong

    2016-10-01

    A novel 3D cross-linked heterostructure of TiO2 nanorods connecting with each other via ultrathin Bi2S3 nanosheets is constructed by a facile and effective strategy. The growth mechanism has been investigated and proposed based on the evolution of microstructure by changing the reaction parameters. Benefiting from the unique cross-linked heterostructure, the as-prepared Bi2S3 nanosheets modified TiO2 nanorods arrays could achieve a high energy conversion efficiency of 3.29% which is the highest value to date for Bi2S3-only sensitized solar cells as the reported highest value is 2.23% and other reported values are less than 1%. Furthermore, the photoelectrochemical studies clearly reveal that the novel cross-linked heterostructure exhibits much better activity than 0D nanoparticles decorated TiO2 nanorods under visible light irradiation, which may be primarily ascribed to the efficient electron transfer from 2D ultrathin Bi2S3 nanosheets to 1D TiO2 nanorod arrays. The promising results in this work confirm the advantages of cross-linked heterostructure and also undoubtedly offer an attractive synthesis strategy to fabricate other nanorod-based hierarchical architecture as well as nano-devices for solar energy conversion.

  14. Dispersions of geometric TiO2 nanomaterials and their toxicity to RPMI 2650 nasal epithelial cells

    Science.gov (United States)

    Tilly, Trevor B.; Kerr, Lei L.; Braydich-Stolle, Laura K.; Schlager, John J.; Hussain, Saber M.

    2014-11-01

    Titanium dioxide (TiO2) based nanofilaments—nanotube, nanowire, nanorod—have gained interest for industrial, electrical, and as of recent, medical applications due to their superior performance over TiO2 nanoparticles. Safety assessment of these nanomaterials is critical to protect workers, patients, and bystanders as these technologies become widely implemented. Additionally, TiO2 based nanofilaments can easily be inhaled by humans and their high aspect ratio, much like asbestos fibers, may make them toxic in the respiratory system. The tendency of TiO2 nanofilaments to aggregate makes evaluating their nanotoxicity difficult and the results controversial, because incomplete dispersion results in larger particle sizes that are no longer in the nano dimensional size range. TiO2 nanofilaments are aggregated and difficult to disperse homogeneously in solution by conventional methods, such as sonication and vortexing. In this study, a microfluidic device was utilized to produce stable, homogeneous dosing solutions necessary for in vitro toxicity evaluation by eliminating any toxicity caused by aggregated TiO2 nanomaterials. The toxicity results could then be directly correlated to the TiO2 nanostructure itself. The toxicity of four TiO2 nanogeometries—nanotube, nanowire, nanorod, and nanoparticle—were assessed in RPMI 2650 human nasal epithelial cells at representative day, week, and month in vitro exposure dosages of 10, 50, 100 μg/ml, respectively. All TiO2 based nanomaterials dispersed by the microfluidic method were nontoxic to RPMI 2650 cells at the concentrations tested, whereas higher concentrations of 100 μg/ml of nanowires and nanotubes dispersed by sonication reduced viability up to 27 %, indicating that in vitro toxicity results may be controlled by the dispersion of dosing solutions.

  15. Synthesis of TiO2/Bi2S3 heterojunction with a nuclear-shell structure and its high photocatalytic activity

    International Nuclear Information System (INIS)

    Lu, Juan; Han, Qiaofeng; Wang, Zuoshan

    2012-01-01

    Highlights: ► Bi 2 S 3 was doped into TiO 2 and it was clearly proved by the expander of the crystalline lattice in XRD result. ► As-prepared TiO 2 /Bi 2 S 3 heterojunctions have a nuclear-shell structure which has not been reported. ► As-prepared TiO 2 /Bi 2 S 3 heterojunctions have the excellent photocatalytic activity. -- Abstract: TiO 2 /Bi 2 S 3 heterojunctions with a nuclear-shell structure were prepared by the coprecipitation method. The products were characterized by X-ray diffraction analysis, Raman spectra, transmission electron microscope images and energy dispersion X-ray spectra. Results showed that as-prepared Bi 2 S 3 was urchin-like, made from many nanorods, and TiO 2 /Bi 2 S 3 heterojunctions have a similar nuclear-shell structure, with Bi 2 S 3 as the shell and TiO 2 as the nuclear. The photocatalytic experiments performed under UV irradiation using methyl orange as the pollutant revealed that the photocatalytic activity of TiO 2 could be improved by introduction of an appropriate amount of Bi 2 S 3 . However, excessive amount of Bi 2 S 3 would result in the decrease of photocatalytic activity of TiO 2 . The relative mechanism was proposed.

  16. The effect of TiO2 nanocrystal shape on the electrical properties of poly(styrene-b-methyl methacrylate) block copolymer based nanocomposites for solar cell application

    International Nuclear Information System (INIS)

    Cano, Laida; Gutierrez, Junkal; Di Mauro, A. Evelyn; Curri, M. Lucia; Tercjak, Agnieszka

    2015-01-01

    Titanium dioxide (TiO 2 ) nanocrystals were synthesized into two shapes, namely spherical and rod-like and used for the fabrication of polystyrene-block-poly(methyl methacrylate) (PSMMA) block copolymer based nanocomposites, which were employed as the active top layer of electro-devices for solar cell application. Electro-devices were designed using nanocomposites with high TiO 2 nanocrystal contents (50-70 wt%) and for comparison as-synthesized TiO 2 nanospheres (TiO 2 NSs) and TiO 2 nanorods (TiO 2 NRs) were also used. The morphology of the electro-devices was studied by atomic force microscopy showing good nanocrystal dispersion. The electrical properties of the devices were investigated by PeakForce tunneling atomic force microscopy and Keithley semiconductor analyzer, which showed higher electrical current values for devices containing TiO 2 NRs in comparison to TiO 2 NSs. Remarkably, the influence of the PSMMA block copolymer on the improvement of the conductivity of the electro-devices was also assessed, demonstrating that the self-assembling ability of block copolymer can be beneficial to improve charge transfer in the fabricated electro-devices, thus representing relevant systems to be potentially developed for photovoltaic applications. Moreover, the absorbance of the prepared electro-devices in solar irradiation range was confirmed by UV–vis spectroscopy characterization.

  17. Whiter, brighter, and more stable cellulose paper coated with TiO2 /SiO2 core/shell nanoparticles using a layer-by-layer approach.

    Science.gov (United States)

    Cheng, Fei; Lorch, Mark; Sajedin, Seyed Mani; Kelly, Stephen M; Kornherr, Andreas

    2013-08-01

    To inhibit the photocatalytic degradation of organic material supports induced by small titania (TiO2 ) nanoparticles, four kinds of TiO2 nanoparticles, that is, commercial P25-TiO2 , commercial rutile phase TiO2 , rutile TiO2 nanorods and rutile TiO2 spheres, prepared from TiCl4 , were coated with a thin, but dense, coating of silica (SiO2 ) using a conventional sol-gel technique to form TiO2 /SiO2 core/shell nanoparticles. These core/shell particles were deposited and fixed as a very thin coating onto the surface of cellulose paper samples by a wet-chemistry polyelectrolyte layer-by-layer approach. The TiO2 /SiO2 nanocoated paper samples exhibit higher whiteness and brightness and greater stability to UV-bleaching than comparable samples of blank paper. There are many potential applications for this green chemistry approach to protect cellulosic fibres from UV-bleaching in sunlight and to improve their whiteness and brightness. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. The effects of solvent on photocatalytic properties of Bi2WO6/TiO2 heterojunction under visible light irradiation

    Science.gov (United States)

    Guo, Qiyao; Huang, Yunfang; Xu, Hui; Luo, Dan; Huang, Feiyue; Gu, Lin; Wei, Yuelin; Zhao, Huang; Fan, Leqing; Wu, Jihuai

    2018-04-01

    Bi2WO6/TiO2 heterojunction photocatalysts with two different microstructures were controllably fabricated via a facile two-step synthetic route. XRD, XPS, SEM, TEM, BET-surface, DRS, PL spectra, photoelectrochemical measurement (Mott-Schottky), and zeta-potential analyzer were employed to clarify structural and morphological characteristics of the obtained products. The results showed that Bi2WO6 nanoparticles/nanosheets grew on the primary TiO2 nanorods. The TiO2 nanorods used as a synthetic template inhibit the growth of Bi2WO6 crystals along the c-axis, resulting in Bi2WO6/TiO2 heterostructure with one-dimensional (1D) morphology. The photocatalytic properties of Bi2WO6/TiO2 heterojunction photocatalysts were strongly dependent on their shapes and structures. Compared with bare Bi2WO6 and TiO2, Bi2WO6/TiO2 composite have stronger adsorption ability and better visible light photocatalytic activities towards organic dyes. The Bi2WO6/TiO2 composite prepared in EG solvent with optimal Bi:Ti ratio of 2:12 (S-TB2) showed the highest photocatalytic activity, which could totally decompose Rhodamine B within 10 min upon irradiation with visible light (λ > 422 nm), and retained the high photocatalytic performance after five recycles, confirming its stability and practical usability. The results of PL indicated that Bi2WO6 and TiO2 could combine well to form a heterojunction structure which facilitated electron-hole separation, and lead to the increasing photocatalytic activity.

  19. Au nanostructure-decorated TiO2 nanowires exhibiting photoactivity across entire UV-visible region for photoelectrochemical water splitting.

    Science.gov (United States)

    Pu, Ying-Chih; Wang, Gongming; Chang, Kao-Der; Ling, Yichuan; Lin, Yin-Kai; Fitzmorris, Bob C; Liu, Chia-Ming; Lu, Xihong; Tong, Yexiang; Zhang, Jin Z; Hsu, Yung-Jung; Li, Yat

    2013-08-14

    Here we demonstrate that the photoactivity of Au-decorated TiO2 electrodes for photoelectrochemical water oxidation can be effectively enhanced in the entire UV-visible region from 300 to 800 nm by manipulating the shape of the decorated Au nanostructures. The samples were prepared by carefully depositing Au nanoparticles (NPs), Au nanorods (NRs), and a mixture of Au NPs and NRs on the surface of TiO2 nanowire arrays. As compared with bare TiO2, Au NP-decorated TiO2 nanowire electrodes exhibited significantly enhanced photoactivity in both the UV and visible regions. For Au NR-decorated TiO2 electrodes, the photoactivity enhancement was, however, observed in the visible region only, with the largest photocurrent generation achieved at 710 nm. Significantly, TiO2 nanowires deposited with a mixture of Au NPs and NRs showed enhanced photoactivity in the entire UV-visible region. Monochromatic incident photon-to-electron conversion efficiency measurements indicated that excitation of surface plasmon resonance of Au is responsible for the enhanced photoactivity of Au nanostructure-decorated TiO2 nanowires. Photovoltage experiment showed that the enhanced photoactivity of Au NP-decorated TiO2 in the UV region was attributable to the effective surface passivation of Au NPs. Furthermore, 3D finite-difference time domain simulation was performed to investigate the electrical field amplification at the interface between Au nanostructures and TiO2 upon SPR excitation. The results suggested that the enhanced photoactivity of Au NP-decorated TiO2 in the UV region was partially due to the increased optical absorption of TiO2 associated with SPR electrical field amplification. The current study could provide a new paradigm for designing plasmonic metal/semiconductor composite systems to effectively harvest the entire UV-visible light for solar fuel production.

  20. Mn-doped CdS quantum dots sensitized hierarchical TiO2 flower-rod for solar cell application

    International Nuclear Information System (INIS)

    Yu, Libo; Li, Zhen; Liu, Yingbo; Cheng, Fa; Sun, Shuqing

    2014-01-01

    A double-layered TiO 2 film which three dimensional (3D) flowers grown on highly ordered self-assembled one dimensional (1D) TiO 2 nanorods was synthesized directly on transparent fluorine-doped tin oxide (FTO) conducting glass substrate by a facile hydrothermal method and was applied as photoanode in Mn-doped CdS quantum dots sensitized solar cells (QDSSCs). The 3D TiO 2 flowers with the increased surface areas can adsorb more QDs, which increased the absorption of light; meanwhile 1D TiO 2 nanorods beneath the flowers offered a direct electrical pathway for photogenerated electrons, accelerating the electron transfer rate. A typical type II band alignment which can effectively separate photogenerated excitons and reduce recombination of electrons and holes was constructed by Mn-doped CdS QDs and TiO 2 flower-rod. The incident photon-to-current conversion efficiency (IPCE) of the Mn-doped CdS/TiO 2 flower-rod solar cell reached to 40% with the polysulfide electrolyte filled in the solar cell. The power conversion efficiency (PCE) of 1.09% was obtained with the Mn-doped CdS/TiO 2 flower-rod solar cell under one sun illumination (AM 1.5G, 100 mW/cm 2 ), which is 105.7% higher than that of the CdS/TiO 2 nanorod solar cell (0.53%).

  1. Three-dimensional self-branching anatase TiO{sub 2} nanorods with the improved carrier collection for SrTiO{sub 3}-based perovskite solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Yajing; Wang, Chen; Tang, Ying; Huang, Lu [Department of Electronic Information Materials, School of Materials Science and Engineering, Shanghai University, Shanghai 200444 (China); Fu, Jianxun [Key Laboratory of Modern Metallurgy and Materials Processing, School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Shi, Weimin; Wang, Linjun [Department of Electronic Information Materials, School of Materials Science and Engineering, Shanghai University, Shanghai 200444 (China); Yang, Weiguang, E-mail: wgyang@shu.edu.cn [Department of Electronic Information Materials, School of Materials Science and Engineering, Shanghai University, Shanghai 200444 (China)

    2016-09-15

    The organic–inorganic perovskite solar cells based on ternary oxide SrTiO{sub 3} shows a higher Voc, attributed to its slightly higher conduction band edge and better morphology of absorber material. However, its less efficient carrier collection and limited overall interfacial areas between the absorber material and the electron-transport layer (ETL), dramatically reducing the Jsc. Here, By adjusting the concentrations of the Ti(OBu){sub 4}, we successfully prepared the three-dimensional (3D) self-branching anatase TiO{sub 2} nanorod/SrTiO{sub 3} nanocomposites, and slightly tuned the particle size of SrTiO{sub 3}. With the incorporation of the three-dimensional (3D) self-branching anatase TiO{sub 2} nanorod, the Jsc of the device based on SrTiO{sub 3} was highly boosted. The best performing solar cell we obtained exhibited a PCE of 9.99% with a Jsc of 19.48 mA/cm{sup 2}. The excellent performance could be ascribed to the improvement of charge carrier collection of SrTiO{sub 3}, better surface coverage and crystallinity of CH{sub 3}NH{sub 3}PbI{sub 3}, and enhanced light scattering ability caused by 3D self-branching anatase TiO{sub 2} nanorods. - Highlights: • The three-dimensional (3D) self-branching anatase TiO{sub 2} nanorod/SrTiO{sub 3} nanocomposites were prepared. • The particle sizes of SrTiO{sub 3} can be slightly tuned. • The best performing solar cell we obtained exhibited a PCE of 9.99% with the Jsc of 19.48 mA/cm{sup 2}.

  2. Characterization and Comparison of Photocatalytic Activity Silver Ion doped on TiO2(TiO2/Ag+) and Silver Ion doped on Black TiO2(Black TiO2/Ag+)

    Science.gov (United States)

    Kim, Jin Yi; Sim, Ho Hyung; Song, Sinae; Noh, Yeoung Ah; Lee, Hong Woon; Taik Kim, Hee

    2018-03-01

    Titanium dioxide (TiO2) is one of the representative ceramic materials containing photocatalyst, optic and antibacterial activity. The hydroxyl radical in TiO2 applies to the intensive oxidizing agent, hence TiO2 is suitable to use photocatalytic materials. Black TiO2was prepared through reduction of amorphous TiO2 conducting under H2 which leads to color changes. Its black color is proven that absorbs 100% light across the whole-visible light, drawing enhancement of photocatalytic property. In this study, we aimed to compare the photocatalytic activity of silver ion doped on TiO2(TiO2/Ag+) and silver ion doped on black TiO2(black TiO2/Ag+) under visible light range. TiO2/Ag+ was fabricated following steps. 1) TiO2 was synthesized by a sol-gel method from Titanium tetraisopropoxide (TTIP). 2) Then AgNO3 was added during an aging process step for silver ion doping on the surface of TiO2. Moreover, Black TiO2/Ag+ was obtained same as TiO2/Ag+ except for calcination under H2. The samples were characterized X-ray diffraction (XRD), UV-visible reflectance (UV-vis DRS), and Methylene Blue degradation test. XRD analysis confirmed morphology of TiO2. The band gap of black TiO2/Ag+ was confirmed (2.6 eV) through UV-vis DRS, which was lower than TiO2/Ag+ (2.9 eV). The photocatalytic effect was conducted by methylene blue degradation test. It demonstrated that black TiO2/Ag+ had a photocatalytic effect under UV light also visible light.

  3. Studied Localized Surface Plasmon Resonance Effects of Au Nanoparticles on TiO2 by FDTD Simulations

    Directory of Open Access Journals (Sweden)

    Guo-Ying Yao

    2018-06-01

    Full Text Available Localized surface plasmon resonance (LSPR plays a significant role in the fields of photocatalysis and solar cells. It can not only broaden the spectral response range of materials, but also improve the separation probability of photo-generated electron-hole pairs through local field enhancement or hot electron injection. In this article, the LSPR effects of Au/TiO2 composite photocatalyst, with different sizes and shapes, have been simulated by the finite difference time domain (FDTD method. The variation tendency of the resonance-absorption peaks and the intensity of enhanced local enhanced electric field were systematically compared and emphasized. When the location of Au nanosphere is gradually immersed into the TiO2 substrate, the local enhanced electric field of the boundary is gradually enhanced. When Au nanoshperes are covered by TiO2 at 100 nm depths, the local enhanced electric field intensities reach the maximum value. However, when Au nanorods are loaded on the surface of the TiO2 substrate, the intensity of the corresponding enhanced local enhanced electric field is the maximum. Au nanospheres produce two strong absorption peaks in the visible light region, which are induced by the LSPR effect and interband transitions between Au nanoparticles and the TiO2 substrate. For the LSPR resonance-absorption peaks, the corresponding position is red-shifted by about 100 nm, as the location of Au nanospheres are gradually immersed into the TiO2 substrate. On the other hand, the size change of the Au nanorods do not lead to a similar variation of the LSPR resonance-absorption peaks, except to change the length-diameter ratio. Meanwhile, the LSPR effects are obviously interfered with by the interband transitions between the Au nanorods and TiO2 substrate. At the end of this article, three photo-generated carrier separation mechanisms are proposed. Among them, the existence of direct electron transfer between Au nanoparticles and the TiO2

  4. Preparation and solar-light photocatalytic activity of TiO2 composites: TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite

    Science.gov (United States)

    Li, Y.; Li, S. G.; Wang, J.; Li, Y.; Ma, C. H.; Zhang, L.

    2014-12-01

    Three TiO2 loaded composites, TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite, were prepared in order to improve the solar-light photocatalytic activity of TiO2. The results showed that the photocatalytic activity could obviously be enhanced by loading appropriate amount of inorganic mineral materials. Meanwhile, TiO2 content, heat-treatment temperature and heat-treatment time on the photocatalytic activity were reviewed. Otherwise, the effect of solar light irradiation time and dye concentration on the photocatalytic degradation of Acid Red B was investigated. Furthermore, the degradation mechanism and adsorption process were also discussed.

  5. Hydrothermal synthesis of 1D TiO2 nanostructures for dye sensitized solar cells

    International Nuclear Information System (INIS)

    Tacchini, I.; Ansón-Casaos, A.; Yu, Youhai; Martínez, M.T.; Lira-Cantu, M.

    2012-01-01

    Highlights: ► Hydrothermal synthesis allows the preparation of different 1D TiO 2 nanostructures easily. ► Nanotubular morphology demonstrates the highest photovoltaic efficiencies in dye sensitized cells (DSCs). ► Morphology at the nanoscale level is as decisive for DSC efficiency as it is TiO 2 crystal structure and surface area. - Abstract: Mono-dimensional titanium oxide nanostructures (multi-walled nanotubes and nanorods) were synthesized by the hydrothermal method and applied to the construction of dye sensitized solar cells (DSCs). First, nanotubes (TiNTs) and nanotubes loaded with titanium oxide nanoparticles (TiNT/NPs) were synthesized with specific surface areas of 253 m 2 /g and 304 m 2 /g, respectively. After that, thermal treatment of the nanotubes at 500 °C resulted in their transformation into the corresponding anatase nanorods (TiNT-Δ and TiNT/NPs-Δ samples). X-ray diffraction and Raman spectroscopy data indicated that titanium oxide in the pristine TiNT and TiNT/NP samples was converted into anatase phase TiO 2 during the heating. Additionally, specific surface areas and water adsorption capacities decreased after the heat treatment due to the sample agglomeration and the collapse of the inner nanotube channels. DSCs were fabricated with the nanotube TiNT and TiNT/NP samples and with the anatase nanorod TiNT-Δ and TiNT/NPs-Δ samples as well. The highest power conversion efficiency of η = 3.12% was obtained for the TiNT sample, despite its lower specific surface compared with the corresponding nanoparticle-loaded sample (TiNT/NP).

  6. 3D periodic multiscale TiO_2 architecture: a platform decorated with graphene quantum dots for enhanced photoelectrochemical water splitting

    International Nuclear Information System (INIS)

    Xu, Zhen; Yin, Min; Lu, Linfeng; Chen, Xiaoyuan; Li, Dongdong; Sun, Jing; Ding, Guqiao; Chang, Paichun

    2016-01-01

    Micropatterned TiO_2 nanorods (TiO_2NRs) via three-dimensional (3D) geometry engineering in both microscale and nanoscale decorated with graphene quantum dots (GQDs) have been demonstrated successfully. First, micropillar (MP) and microcave (MC) arrays of anatase TiO_2 films are obtained through the sol–gel based thermal nanoimprinting method. Then they are employed as seed layers in hydrothermal growth to fabricate the 3D micropillar/microcave arrays of rutile TiO_2NRs (NR), which show much-improved photoelectrochemical water-splitting performance than the TiO_2NRs grown on flat seed layer. The zero-dimensional GQDs are sequentially deposited onto the surfaces of the microscale patterned nanorods. Owing to the fast charge separation that resulted from the favorable band alignment of the GQDs and rutile TiO_2, the MP-NR-GQDs electrode achieves a photocurrent density up to 2.92 mA cm"−"2 under simulated one-sun illumination. The incident-photon-to-current-conversion efficiency (IPCE) value up to 72% at 370 nm was achieved on the MP-NR-GQDs electrode, which outperforms the flat-NR counterpart by 69%. The IPCE results also imply that the improved photocurrent mainly benefits from the distinctly enhanced ultraviolet response. The work provides a cost-effective and flexible pathway to develop periodic 3D micropatterned photoelectrodes and is promising for the future deployment of high performance optoelectronic devices. (paper)

  7. TiO2 brookite nanostructured thin layer on magneto-optical surface plasmon resonance transductor for gas sensing applications

    Science.gov (United States)

    Manera, M. G.; Colombelli, A.; Rella, R.; Caricato, A.; Cozzoli, P. D.; Martino, M.; Vasanelli, L.

    2012-09-01

    The sensing performance comparisons presented in this work were carried out by exploiting a suitable magneto-plasmonic sensor in both the traditional surface plasmon resonance configuration and the innovative magneto-optic surface plasmon resonance one. The particular multilayer transducer was functionalized with TiO2 Brookite nanorods layers deposited by matrix assisted pulsed laser evaporation, and its sensing capabilities were monitored in a controlled atmosphere towards different concentrations of volatile organic compounds mixed in dry air.

  8. Surface nanostructuring of TiO2 thin films by ion beam irradiation

    International Nuclear Information System (INIS)

    Romero-Gomez, P.; Palmero, A.; Yubero, F.; Vinnichenko, M.; Kolitsch, A.; Gonzalez-Elipe, A.R.

    2009-01-01

    This work reports a procedure to modify the surface nanostructure of TiO 2 anatase thin films through ion beam irradiation with energies in the keV range. Irradiation with N + ions leads to the formation of a layer with voids at a depth similar to the ion-projected range. By setting the ion-projected range a few tens of nanometers below the surface of the film, well-ordered nanorods appear aligned with the angle of incidence of the ion beam. Slightly different results were obtained by using heavier (S + ) and lighter (B + ) ions under similar conditions

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

    Science.gov (United States)

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

    2018-05-01

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

  10. Controllable synthesis of TiO2 nanomaterials by assisting with l-cysteine and ethylenediamine

    KAUST Repository

    Tao, Yugui

    2013-11-21

    This paper reports a facile l-cysteine-assisted solvothermal synthesis of TiO2 nanomaterials using ethylenediamine (En) and distilled water as solvent. The influence of reaction time, temperature, l-cysteine and solvent was initially investigated. Results demonstrated the reaction temperature, l-cysteine and En significantly imposed impact on the phase and morphology of the particles. Amorphous nanosheets, mixed-crystal nanorods and pure anatase nanoparticles were controllably synthesized by varying reaction temperature. The formation of the amorphous nanosheets and mixed-crystal nanorods were directly affected by the presence of l-cysteine and En. And the presence of En distinctly affected the crystal phase of the products, which was rarely mentioned in other studies. Moreover, the photocatalytic activities of three typical samples were excellent. The possible formation mechanism of the sample was also discussed. © 2013 Springer Science+Business Media New York.

  11. Controllable synthesis of TiO2 nanomaterials by assisting with l-cysteine and ethylenediamine

    KAUST Repository

    Tao, Yugui; Cao, Ning; Pan, Jun; Sun, Yichen; Jin, Cheng; Song, Yang

    2013-01-01

    This paper reports a facile l-cysteine-assisted solvothermal synthesis of TiO2 nanomaterials using ethylenediamine (En) and distilled water as solvent. The influence of reaction time, temperature, l-cysteine and solvent was initially investigated. Results demonstrated the reaction temperature, l-cysteine and En significantly imposed impact on the phase and morphology of the particles. Amorphous nanosheets, mixed-crystal nanorods and pure anatase nanoparticles were controllably synthesized by varying reaction temperature. The formation of the amorphous nanosheets and mixed-crystal nanorods were directly affected by the presence of l-cysteine and En. And the presence of En distinctly affected the crystal phase of the products, which was rarely mentioned in other studies. Moreover, the photocatalytic activities of three typical samples were excellent. The possible formation mechanism of the sample was also discussed. © 2013 Springer Science+Business Media New York.

  12. One-Step Nonaqueous Synthesis of Pure Phase TiO2 Nanocrystals from TiCl4 in Butanol and Their Photocatalytic Properties

    Directory of Open Access Journals (Sweden)

    Tieping Cao

    2011-01-01

    Full Text Available Pure phase TiO2 nanomaterials were synthesized by an autoclaving treatment of TiCl4 with butanol as a single alcohol source. It was found that the control of molar ratio of TiCl4 to butanol played an important role in determining the TiO2 crystal phase and morphology. A high molar ratio of TiCl4 to butanol favored the formation of anatase nanoparticles, whereas rutile nanorods were selectively obtained at a low molar ratio of TiCl4 to butanol. Evaluation of the photocatalytic activity of the synthesized TiO2 was performed in terms of decomposition of organic dye rhodamine B under ultraviolet irradiation. It turned out that the as-synthesized TiO2 crystallites possessed higher photocatalytic activities toward bleaching rhodamine B than Degussa P25, benefiting from theirhigh surface area, small crystal size as well as high crystallinity.

  13. Functionalized TiO2 nanoparticle containing isocyanate groups

    International Nuclear Information System (INIS)

    Ou, Baoli; Li, Duxin; Liu, Qingquan; Zhou, Zhihua; Liao, Bo

    2012-01-01

    Functionalized TiO 2 nanoparticle containing isocyanate groups can extend the TiO 2 nanoparticle chemistry, and may promote their many potential applications such as in polymer composites and coatings. This paper describes a facile method to prepare functionalized TiO 2 nanoparticle with highly reactive isocyanate groups on its surface, via the reaction between toluene-2, 4-diisocyanate (TDI) and hydroxyl on TiO 2 nanoparticle surface. The main effect factors on the reaction of TiO 2 with TDI were studied by determining the reaction extent of hydroxyl groups on TiO 2 surface. Fourier-transformed infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) confirmed that reactive isocyanate groups were covalently attached to the TiO 2 nanoparticle surface. The dispersion of the TDI-functionalized TiO 2 nanoparticle was studied by transmission electron microscopy (TEM). Owing to the TDI molecules covalently bonded on TiO 2 nanoparticle surface, it was established that the TiO 2 nanoparticle can be uniformly dispersed in toluene, thus indicating that this functionalization method can prevent TiO 2 nanoparticle from agglomerating. -- Highlights: ► TiO 2 nanoparticle was functionalized with toluene-2, 4-diisocyanate. ► Functionalized TiO 2 nanoparticle can be uniformly dispersed in xylene. ► Compatibility of TiO 2 nanoparticle and organic solvent is significantly improved. ► TiO 2 containing isocyanate groups can extend the TiO 2 nanoparticle chemistry.

  14. Instability of Hydrogenated TiO2

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

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

    2017-03-01

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

  16. Preparation of micro/nanostructure TiO2 spheres by controlling pollen as hard template and soft template.

    Science.gov (United States)

    Yang, Xiaohui; Xu, Bin; Zhang, Xuehong; Song, Xiuqin; Chen, Rufen

    2014-09-01

    In this paper, micro/nanostructure TiO2 spheres were synthesized by a sunflower pollen induced and self-assembly mineralization process, in which a titania precursor and pollen reacted in one-pot at normal pressure. In this paper, the bio-template advantage, as hard and soft template is fully demonstrated. The superiority of our synthesis is that we not only can control pollen as hard template, but also can control it as soft template only by changing reactions temperature. Under 80 degrees C of water bath, TiO2 microspheres which replicated the morphology of pollen were prepared by controlling pollen as hard template. Under 100 degrees C, hierarchical TiO2 spheres with complicated morphology, different from pollen template, were synthesized by using pollen as soft template. At the same time, judicious choice of the amount of pollen affords the synthesis of hierarchical structures spheres with adjustable morphology and crystal structure. The morphology can be tuned from microspheres constructed from TiO2 nanorods to nanospheres constructed from TiO2 nanoparticles, and the crystal structure can be tuned from rutile to anatase. More over this anatase phase can be keep better even at high temperature of 1000 degrees C. The as-prepared micro/nano structure photocatalysts not only have high photocatalytic activities, but also have good separability and reuse performance.

  17. Degradation of the ammonia wastewater in aqueous medium with ozone in combination with mesoporous TiO2 catalytic

    Science.gov (United States)

    Liu, Zhiwu; Qiu, Jianping; Zheng, Chaocan; Li, Liqing

    2017-03-01

    TiO2 mesoporous nanomaterials are now widely used in catalytic ozone technology. In this paper, the market P25 as precursor hydrothermal method to prepare TiO2 mesoporous materials, ozone catalyst material characterization by transmission electron microscopy, surface area analyzers, and X-ray diffraction technique and found that nanotubes, nanosheets, nanorods through characterization results, nano-particles of different morphology and anatase and rutile proportion of the ozone catalytic material can be controlled by the calcination temperature and the temperature of hot water to give, and with the hot water temperature and calcination temperature, the catalyst becomes small aperture size larger catalyst crystalline phase from anatase to rutile gradually shift. Catalytic materials have been prepared by the Joint ozone degradation of ammonia wastewater to evaluate mesoporous TiO2 nanomaterials ozone catalytic performance, the results showed that: ammonia wastewater removal efficiency of various catalytic materials relatively separate ozone and markets P25 effects are significantly improved, and TiO2 nanotubes cooperate with ozone degradation ammonia wastewater highest efficiency, in addition, rutile TiO2 catalysts, the more the better the performance of their ozone catalysis.

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

    International Nuclear Information System (INIS)

    Ghalamboran, Milad; Saedi, Yasin

    2016-01-01

    The fabrication method and characterization results of a TiO 2 -TiO 2 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 TiO 2 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 TiO 2 crystallites embedded in a matrix of nanometric TiO 2 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. (paper)

  19. Mesoporous 1D TiO_2 nanostructures obtained by the hydrothermal method

    International Nuclear Information System (INIS)

    Cabrera, Julieta; Vilchez, Ricardo; Alarcon, Hugo; Rodriguez, Juan; Lopez, Alcides

    2014-01-01

    Mesoporous one dimensional nanostructures (1D) such as nanotubes/nanorods of TiO_2 were synthesized by alkaline hydrothermal treatment of TiO_2 nanoparticles obtained by Sol Gel process (SG-TiO_2). The electronic microscopy images revealed the nanotubes formation of approximately 8 nm in diameter and more than around 400 nm long after hydrothermal treatment of 18 h and 24 h. These tube-like structures were maintained after acid treatment but after annealing at 400 °C during 2 hours these turn into rod-like structures of crystalline TiO_2 corresponding to anatase phase as revealed the diffraction patterns obtained by X-Ray Diffraction (XRD). The conversion of nanoparticles into nanotubes and afterward into rodlike shape was also confirmed by the variations in the BET surface area from 201, 269 and 97 m"2/g around, respectively. The adsorption-desorption isotherms also revealed hysteresis loop typical of mesoporous materials. These qualities are attractive to use these materials for the treatment of pollutants in water, for example. (author)

  20. Existence, release, and antibacterial actions of silver nanoparticles on Ag–PIII TiO2 films with different nanotopographies

    Directory of Open Access Journals (Sweden)

    Li J

    2014-07-01

    Full Text Available Jinhua Li, Yuqin Qiao, Hongqin Zhu, Fanhao Meng, Xuanyong Liu State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, People’s Republic of China Abstract: Nanotopographical TiO2 films (including nanorod, nanotip, and nanowire topographies were successfully fabricated on the metallic Ti surface via hydrothermal treatment and then underwent Ag plasma immersion ion implantation to incorporate Ag with TiO2. The surface morphology, phase component, and chemical composition before and after Ag–PIII were characterized. In view of the potential clinical applications, both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus were used to estimate their antimicrobial effect. The nanostructured TiO2 films on a Ti surface exhibit a better bacteriostatic effect on both microbes compared to the pristine Ti. The nanotopographies of the TiO2 films affect the nucleation, growth, and distribution of Ag nanoparticles in the films during Ag–PIII process. The Ag nanoparticles are completely embedded into the nanorod film while partially exposed out of the nanotip and nanowire films, which account for the significant differences in the release behaviors of Ag ions in vitro. However, no significant difference exists in their antimicrobial activity against both microbes. The antimicrobial actions of the Ag@TiO2 system described here consist of two methods – the contact-killing action and the release-killing action. Nevertheless, based on the observed results, the contact-killing action should be regarded as the main method to destroy microbes for all the Ag plasma-modified TiO2 nanofilms. This study provides insight to optimize the surface design of Ti-based implants to acquire more effective antimicrobial surfaces to meet clinical applications. Keywords: silver, nanoparticles, titania, nanostructure, antibacterial, plasma

  1. Water Adsorption on TiO2

    DEFF Research Database (Denmark)

    Hammer, Bjørk; Wendt, Stefan; Besenbacher, Flemming

    2010-01-01

    Scanning Tunneling Microscopy (STM) studies and Density Functional Theory (DFT) investigations of the interaction of water with the rutile TiO2 (110) surface are summarized. From high-resolution STM the following reactions have been revealed: water adsorption and diffusion in the Ti troughs, water...... dissociation in bridging oxygen vacancies, assembly of adsorbed water monomers into rapidly diffusing water dimers, and formation of water dimers by reduction of oxygen molecules. The STM results are rationalized based on DFT calculations, revealing the bonding geometries and reaction pathways of the water...

  2. Hierarchical architectures of ZnS–In2S3 solid solution onto TiO2 nanofibers with high visible-light photocatalytic activity

    International Nuclear Information System (INIS)

    Liu, Chengbin; Meng, Deshui; Li, Yue; Wang, Longlu; Liu, Yutang; Luo, Shenglian

    2015-01-01

    Graphical abstract: A unique hierarchical architecture of ZnS–In 2 S 3 solid solution onto TiO 2 nanofibers was fabricated. The hierarchical heterostructures exhibit high visible light photocatalytic activity and outstanding recycling performance. - Highlights: • Novel hierarchical heterostructure of TiO 2 @ZnS–In 2 S 3 solid solution. • Efficient inhibition of ZnS–In 2 S 3 solid solution aggregation. • High visible light photocatalytic activity. • Highly stable recycling performance. - Abstract: A unique hierarchical architecture of ZnS–In 2 S 3 solid solution nanostructures onto TiO 2 nanofibers (TiO 2 @ZnS–In 2 S 3 ) has been successfully fabricated by simple hydrothermal method. The ZnS–In 2 S 3 solid solution nanostructures exhibit a diversity of morphologies: nanosheet, nanorod and nanoparticle. The porous TiO 2 nanofiber templates effectively inhibit the aggregation growth of ZnS–In 2 S 3 solid solution. The formation of ZnS–In 2 S 3 solid solution is proved by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) and the intimate contact between TiO 2 nanofibers and ZnS–In 2 S 3 solid solution favors fast transfer of photogenerated electrons. The trinary TiO 2 @ZnS–In 2 S 3 heterostructures exhibit high adsorption capacity and visible light photocatalytic activity for the degradation of rhodamine B dye (RhB), remarkably superior to pure TiO 2 nanofibers or binary structures (ZnS/TiO 2 nanofibers, In 2 S 3 /TiO 2 nanofibers and ZnS–In 2 S 3 solid solution). Under visible light irradiation the RhB photocatalytic degradation rate over TiO 2 @ZnS–In 2 S 3 heterostructures is about 16.7, 12.5, 6.3, 5.9, and 2.2 times that over pure TiO 2 nanofibers, ZnS nanoparticles, In 2 S 3 /TiO 2 nanofibers, ZnS/TiO 2 nanofibers, and ZnS-In 2 S 3 solid solution, respectively. Furthermore, the TiO 2 @ZnS–In 2 S 3 heterostructures show highly stable recycling performance

  3. TiO2/PbS/ZnS heterostructure for panchromatic quantum dot sensitized solar cells synthesized by wet chemical route

    Science.gov (United States)

    Bhat, T. S.; Mali, S. S.; Sheikh, A. D.; Korade, S. D.; Pawar, K. K.; Hong, C. K.; Kim, J. H.; Patil, P. S.

    2017-11-01

    So far we developed the efficient photoelectrodes which can harness the UV as well as the visible regime of the solar spectrum effectively. In order to exploit a maximum portion of solar spectrum, it is necessary to study the synergistic effect of a photoelectrode comprising UV and visible radiations absorbing materials. Present research work highlights the efforts to study the synchronized effect of TiO2 and PbS on the power conversion efficiency of quantum dot sensitized solar cell (QDSSC). A cascade structure of TiO2/PbS/ZnS QDSSC is achieved to enhance the photoconversion efficiency of TiO2/PbS system by incorporating a surface passivation layer of ZnS which avoids the recombination of charge carriers. A QDSSC is fabricated using a simple and cost-effective technique such as hydrothermally grown TiO2 nanorod arrays decorated with PbS and ZnS using successive ionic layer adsorption and reaction (SILAR) method. Synthesized electrode materials are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), High resolution-transmission electron microscopy (TEM), STEM-EDS mapping, optical and solar cell performances. Phase formation of TiO2, PbS and ZnS get confirmed from the XPS study. FE-SEM images of the photoelectrode show uniform coverage of PbS QDs onto the TiO2 nanorods which increases with increasing number of SILAR cycles. The ZnS layer not only improves the charge transport but also reduces the photocorrosion of lead chalcogenides in the presence of a liquid electrolyte. Finally, the photoelectrochemical (PEC) study is carried out using an optimized photoanode comprising TiO2/PbS/ZnS assembly. Under AM 1.5G illumination the TiO2/PbS/ZnS QDSSC photoelectrode shows 4.08 mA/cm2 short circuit current density in a polysulfide electrolyte which is higher than that of a bare TiO2 nanorod array.

  4. One-pot engineering TiO2/graphene interface for enhanced adsorption and photocatalytic degradation of multiple organics.

    Science.gov (United States)

    Song, Jianhua; Ling, Yun; Xie, Yu; Liu, Lianjun; Zhu, Huihua

    2018-06-13

    It is challenging to design a multifunctional structure or composite for simultaneously adsorb and photocatalytic degrade organic pollutants in water. Towards this goal, this work innovatively engineered interfacial sites between TiO2 particles and reduced graphene oxide (RGO) sheets by employing in situ one-pot one-step solvothermal method. The interface was associated with the content of RGO, solvothermal time and solvent ratio of n-pentanol to n-hexane. It was found that when at a moderate amount of RGO (25%), TiO2 nanoparticles were well dispersed on the surface of RGO or wrapped by RGO, thus leading to a fully contact and strong interaction to form Ti - O - C interfacial structure. But when at a low content of RGO (6%), TiO2 aggregates were mixture of nanosheets, nanoparticles and nanorods. 25%RGO/TiO2 also had 175% higher surface area (146m2/g), 95% larger volume (0.339 cm3/g) and smaller band gap than 6%RGO/TiO2. More importantly, 25%RGO/TiO2 demonstrated higher adsorption efficiency (25%) and 4 times faster degradation rate than TiO2 (0%). It also exhibited good capability to eliminate multiple organics and stable long-term cycle performance (up to 93% retention after 30 cycles). Its superiority was attributed to the large surface area and unique interface between TiO2 and RGO, which not only provided more active sites to capture pollutants but also enhanced charge transfer (3 µA/cm2, 5 times higher than TiO2). This work offered a promising way to purify water through engineering new materials structure and integrating adsorption and photodegradation technologies. © 2018 IOP Publishing Ltd.

  5. Hierarchical (0 0 1) facet anatase/rutile TiO2 heterojunction photoanode with enhanced photoelectrocatalytic performance

    International Nuclear Information System (INIS)

    Tian, Hongyi; Zhao, Guohua; Zhang, Ya-nan; Wang, Yanbin; Cao, Tongcheng

    2013-01-01

    Highlights: ► (0 0 1) facet TiO 2 photoanode with large surface area is reported for the first time. ► Ordered heterojunction further improves light absorption in (0 0 1) facet TiO 2 system. ► (0 0 1) facet TiO 2 photoanode possesses promoted photoelectrocatalytic performance. ► Photoelectrical enhancement mechanism is clarified by electrochemical methods. ► Photogenerated carrier and lifetime are remarkably enhanced by ingenious design. -- Abstract: A hierarchical heterojunction TiO 2 photoanode with large surface/body ratio is reported to exhibit high oxidation activity due to the constructing of anatase TiO 2 with exposed (0 0 1) facets. The mixed-phase photoanode is fabricated through surfactant-assisted anchoring ultrathin anatase nanosheets on vertically ordered rutile nanorod arrays. This cactaceae-like TiO 2 possesses high-exposed (0 0 1) facets outer layer, large specific surface area (375 m 2 g −1 ), efficient photo-to-current conversion (8.2%) and excellent photocatalytic ability to degrade bisphenol A. The greatly promoted photoelectric and photocatalytic performance results from the synergetic effects of the architecture design of high-active (0 0 1) facets and hierarchical heterojunctions. The mechanism analysis reveals that the remarkable increase of photogenerated carrier concentration (2.40 × 10 22 cm −3 ) improves photocatalytic activity, by virtue of constructing staggered energy levels, suppressing the recombination of electrons and holes, and extending the electron lifetime (133 ms)

  6. Hierarchical architectures TiO2: Pollen-inducted synthesis, remarkable crystalline-phase stability, tunable size, and reused photo-catalysis

    International Nuclear Information System (INIS)

    Dou, Lingling; Gao, Lishuang; Yang, Xiaohui; Song, Xiuqin

    2012-01-01

    Highlights: ► The synthetic method is much milder and simpler than that of conventional methods. ► The obtained hierarchical TiO 2 shows three interesting hierarchical morphology. ► The products have tunable crystal phase structures. ► The pure phase of anatase can be retained after being annealed at 900 °C. ► The product exhibits higher and reused photo-catalytic activity. - Abstract: TiO 2 with hierarchical architectures, tunable crystalline phase and thermal stability is successfully fabricated on a large scale through a facile hydrolysis process of TiCl 4 combining with inducing of pollen. The structure of the as-prepared TiO 2 is characterized by X-ray diffraction, Raman spectroscopy, infrared spectra, and scanning electron microscopy. The experimental results indicate that different phases (anatase, rutile or mixed crystallite) of TiO 2 can be synthesized by controlling the experimental conditions. The pure phase of rutile or anatase can be obtained at 100 °C, while the pure phase of anatase can be retained after being annealed at 900 °C. The hierarchical structures TiO 2 are constitute through self-assembly of nanoparticles or nanorods TiO 2 , which exhibit high and reused photo-catalytic properties for degradation of methylene blue.

  7. Promoted Fixation of Molecular Nitrogen with Surface Oxygen Vacancies on Plasmon-Enhanced TiO2 Photoelectrodes.

    Science.gov (United States)

    Li, Chengcheng; Wang, Tuo; Zhao, Zhi-Jian; Yang, Weimin; Li, Jian-Feng; Li, Ang; Yang, Zhilin; Ozin, Geoffrey A; Gong, Jinlong

    2018-02-19

    A hundred years on, the energy-intensive Haber-Bosch process continues to turn the N 2 in air into fertilizer, nourishing billions of people while causing pollution and greenhouse gas emissions. The urgency of mitigating climate change motivates society to progress toward a more sustainable method for fixing N 2 that is based on clean energy. Surface oxygen vacancies (surface O vac ) hold great potential for N 2 adsorption and activation, but introducing O vac on the very surface without affecting bulk properties remains a great challenge. Fine tuning of the surface O vac by atomic layer deposition is described, forming a thin amorphous TiO 2 layer on plasmon-enhanced rutile TiO 2 /Au nanorods. Surface O vac in the outer amorphous TiO 2 thin layer promote the adsorption and activation of N 2 , which facilitates N 2 reduction to ammonia by excited electrons from ultraviolet-light-driven TiO 2 and visible-light-driven Au surface plasmons. The findings offer a new approach to N 2 photofixation under ambient conditions (that is, room temperature and atmospheric pressure). © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  9. Fabrication of a TiO2-P25/(TiO2-P25+TiO2 nanotubes junction for dye sensitized solar cells

    Directory of Open Access Journals (Sweden)

    Nguyen Huy Hao

    2016-08-01

    Full Text Available The dye sensitized solar cell (DSSC, which converts solar light into electric energy, is expected to be a promising renewable energy source for today's world. In this work, dye sensitized solar cells, one containing a single layer and one containing a double layer, were fabricated. In the double layer DSSC structure, the under-layer was TiO2-P25 film, and the top layer consisted of a mixture of TiO2-P25 and TiO2 nanotubes. The results indicated that the efficiency of the DSSC with the double layer structure was a significant improvement in comparison to the DSSC consisting of only a single film layer. The addition of TiO2-P25 in the top layer caused an improvement in the adsorption of dye molecules on the film rather than on the TiO2 nanotubes only. The presence of the TiO2 nanotubes together with TiO2-P25 in the top layer revealed the enhancement in harvesting the incident light and an improvement of electron transport through the film.

  10. TiO2 beads and TiO2-chitosan beads for urease immobilization

    International Nuclear Information System (INIS)

    Ispirli Doğaç, Yasemin; Deveci, İlyas; Teke, Mustafa; Mercimek, Bedrettin

    2014-01-01

    The aim of the present study is to synthesize TiO 2 beads for urease immobilization. Two different strategies were used to immobilize the urease on TiO 2 beads. In the first method (A), urease enzyme was immobilized onto TiO 2 beads by adsorption and then crosslinking. In the second method (B), TiO 2 beads were coated with chitosan-urease mixture. To determine optimum conditions of immobilization, different parameters were investigated. The parameters of optimization were initial enzyme concentration (0.5; 1; 1.5; 2 mg/ml), alginate concentration (1; 2; 3%), glutaraldehyde concentration (1; 2; 3% v/v) and chitosan concentration (2; 3; 4 mg/ml). The optimum enzyme concentrations were determined as 1.5 mg/ml for A and 1.0 mg/ml for B. The other optimum conditions were found 2.0% (w/v) for alginate concentration (both A and B); 3.0 mg/ml for chitosan concentration (B) and 2.0% (v/v) for glutaraldehyde concentration (A). The optimum temperature (20-60 °C), optimum pH (3.0-10.0), kinetic parameters, thermal stability (4–70 °C), pH stability (4.0-9.0), operational stability (0-230 min) and reusability (20 times) were investigated for characterization. The optimum temperatures were 30 °C (A), 40 °C (B) and 35 °C (soluble). The temperature profiles of the immobilized ureases were spread over a large area. The optimum pH values for the soluble urease and immobilized urease prepared by using methods (A) and (B) were found to be 7.5, 7.0, 7.0, respectively. The thermal stabilities of immobilized enzyme sets were studied and they maintained 50% activity at 65 °C. However, at this temperature free urease protected only 15% activity. - Highlights: • TiO 2 and TiO 2 -chitosan beads for urease immobilization have been prepared and characterized. • The beads used in this work are good matrices for the immobilization of urease. • The immobilized urease was shown to have good properties and stabilities (pH and thermal stability, operational stability). • The 50% activity was protected after 11 cycles for method A and 16 cycles for method B

  11. Controlled Directional Growth of TiO2 Nanotubes

    DEFF Research Database (Denmark)

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

    2010-01-01

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

  12. Silicon protected with atomic layer deposited TiO2

    DEFF Research Database (Denmark)

    Seger, Brian; Tilley, S. David; Pedersen, Thomas

    2013-01-01

    The present work demonstrates that tuning the donor density of protective TiO2 layers on a photocathode has dramatic consequences for electronic conduction through TiO2 with implications for the stabilization of oxidation-sensitive catalysts on the surface. Vacuum annealing at 400 °C for 1 hour o...

  13. Preparation, characterization and photocatalytic activity of TiO2 ...

    Indian Academy of Sciences (India)

    Photocatalyst; TiO2 nanoparticle; polyaniline; conducting polymer; core-shell nanocomposite. 1. Introduction ..... tine TiO2 nanoparticles, HCl-doped PANI and PANI/TiO2 ..... Karim M R, Lim K T, Lee M S, Kim K and Yeum J H 2009 Synth. Met.

  14. Optimized nanostructured TiO2 photocatalysts

    Science.gov (United States)

    Topcu, Selda; Jodhani, Gagan; Gouma, Pelagia

    2016-07-01

    Titania is the most widely studied photocatalyst. In it’s mixed-phase configuration (anatase-rutile form) -as manifested in the commercially available P25 Degussa material- titania was previously found to exhibit the best photocatalytic properties reported for the pure system. A great deal of published research by various workers in the field have not fully explained the underlying mechanism for the observed behavior of mixed-phase titania photocatalysts. One of the prevalent hypothesis in the literature that is tested in this work involves the presence of small, active clusters of interwoven anatase and rutile crystallites or “catalytic “hot-spots””. Therefore, non-woven nanofibrous mats of titania were produced and upon calcination the mats consisted of nanostructured fibers with different anatase-rutile ratios. By assessing the photocatalytic and photoelectrochemical properties of these samples the optimized photocatalyst was determined. This consisted of TiO2 nanostructures annealed at 500˚C with an anatase /rutile content of 90/10. Since the performance of this material exceeded that of P25 complete structural characterization was employed to understand the catalytic mechanism involved. It was determined that the dominant factors controlling the photocatalytic behavior of the titania system are the relative particle size of the different phases of titania and the growth of rutile laths on anatase grains which allow for rapid electron transfer between the two phases. This explains how to optimize the response of the pure system.

  15. Antibacterial activity and inflammation inhibition of ZnO nanoparticles embedded TiO2 nanotubes

    Science.gov (United States)

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

    2018-06-01

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

  16. Oriented epitaxial TiO2 nanowires for water splitting

    Science.gov (United States)

    Hou, Wenting; Cortez, Pablo; Wuhrer, Richard; Macartney, Sam; Bozhilov, Krassimir N.; Liu, Rong; Sheppard, Leigh R.; Kisailus, David

    2017-06-01

    Highly oriented epitaxial rutile titanium dioxide (TiO2) nanowire arrays have been hydrothermally grown on polycrystalline TiO2 templates with their orientation dependent on the underlying TiO2 grain. Both the diameter and areal density of the nanowires were tuned by controlling the precursor concentration, and the template surface energy and roughness. Nanowire tip sharpness was influenced by precursor solubility and diffusivity. A new secondary ion mass spectrometer technique has been developed to install additional nucleation sites in single crystal TiO2 templates and the effect on nanowire growth was probed. Using the acquired TiO2 nanowire synthesis knowhow, an assortment of nanowire arrays were installed upon the surface of undoped TiO2 photo-electrodes and assessed for their photo-electrochemical water splitting performance. The key result obtained was that the presence of short and dispersed nanowire arrays significantly improved the photocurrent when the illumination intensity was increased from 100 to 200 mW cm-2. This is attributed to the alignment of the homoepitaxially grown nanowires to the [001] direction, which provides the fastest charge transport in TiO2 and an improved pathway for photo-holes to find water molecules and undertake oxidation. This result lays a foundation for achieving efficient water splitting under conditions of concentrated solar illumination.

  17. TiO2 nanowire-templated hierarchical nanowire network as water-repelling coating

    Science.gov (United States)

    Hang, Tian; Chen, Hui-Jiuan; Xiao, Shuai; Yang, Chengduan; Chen, Meiwan; Tao, Jun; Shieh, Han-ping; Yang, Bo-ru; Liu, Chuan; Xie, Xi

    2017-12-01

    Extraordinary water-repelling properties of superhydrophobic surfaces make them novel candidates for a great variety of potential applications. A general approach to achieve superhydrophobicity requires low-energy coating on the surface and roughness on nano- and micrometre scale. However, typical construction of superhydrophobic surfaces with micro-nano structure through top-down fabrication is restricted by sophisticated fabrication techniques and limited choices of substrate materials. Micro-nanoscale topographies templated by conventional microparticles through surface coating may produce large variations in roughness and uncontrollable defects, resulting in poorly controlled surface morphology and wettability. In this work, micro-nanoscale hierarchical nanowire network was fabricated to construct self-cleaning coating using one-dimensional TiO2 nanowires as microscale templates. Hierarchical structure with homogeneous morphology was achieved by branching ZnO nanowires on the TiO2 nanowire backbones through hydrothermal reaction. The hierarchical nanowire network displayed homogeneous micro/nano-topography, in contrast to hierarchical structure templated by traditional microparticles. This hierarchical nanowire network film exhibited high repellency to both water and cell culture medium after functionalization with fluorinated organic molecules. The hierarchical structure templated by TiO2 nanowire coating significantly increased the surface superhydrophobicity compared to vertical ZnO nanowires with nanotopography alone. Our results demonstrated a promising strategy of using nanowires as microscale templates for the rational design of hierarchical coatings with desired superhydrophobicity that can also be applied to various substrate materials.

  18. A large interconnecting network within hybrid MEH-PPV/TiO2 nanorod photovoltaic devices

    International Nuclear Information System (INIS)

    Zeng, T-W; Lin, Y-Y; Lo, H-H; Chen, C-W; Chen, C-H; Liou, S-C; Huang, H-Y; Su, W-F

    2006-01-01

    This is a study of hybrid photovoltaic devices based on TiO 2 nanorods and poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV). We use TiO 2 nanorods as the electron acceptors and conduction pathways. Here we describe how to develop a large interconnecting network within the photovoltaic device fabricated by inserting a layer of TiO 2 nanorods between the MEH-PPV:TiO 2 nanorod hybrid active layer and the aluminium electrode. The formation of a large interconnecting network provides better connectivity to the electrode, leading to a 2.5-fold improvement in external quantum efficiency as compared to the reference device without the TiO 2 nanorod layer. A power conversion efficiency of 2.2% under illumination at 565 nm and a maximum external quantum efficiency of 24% at 430 nm are achieved. A power conversion efficiency of 0.49% is obtained under Air Mass 1.5 illumination

  19. Fabrication and Characteristics of Macroporous TiO2 Photocatalyst

    Directory of Open Access Journals (Sweden)

    Guiyun Yi

    2014-01-01

    Full Text Available Macroporous TiO2 photocatalyst was synthesized by a facile nanocasting method using polystyrene (PS spherical particles as the hard template. The synthesized photocatalyst was characterized by transmission electron microscope (TEM, scanning electron microscopy (SEM, thermogravimetry-differential thermogravimetry (TG-DTG, X-ray diffraction (XRD, and N2-sorption. TEM, SEM, and XRD characterizations confirmed that the macroporous TiO2 photocatalyst is composed of anatase phase. The high specific surface area of 87.85 m2/g can be achieved according to the N2-sorption analysis. Rhodamine B (RhB was chosen as probe molecule to evaluate the photocatalytic activity of the TiO2 catalysts. Compared with the TiO2 materials synthesized in the absence of PS spherical template, the macroporous TiO2 photocatalyst sintered at 500°C exhibits much higher activity on the degradation of RhB under the UV irradiation, which can be assigned to the well-structured macroporosity. The macroporous TiO2 material presents great potential in the fields of environmental remediation and energy conversion and storage.

  20. High pressure synthesis of amorphous TiO2 nanotubes

    Directory of Open Access Journals (Sweden)

    Quanjun Li

    2015-09-01

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

  1. TiO2-ITO and TiO2-ZnO nanocomposites: application on water treatment

    Directory of Open Access Journals (Sweden)

    Bessais B.

    2012-06-01

    Full Text Available One of the most promising ideas to enhance the photocatalytic efficiency of the TiO2 is to couple this photocatalyst with other semiconductors. In this work, we report on the development of photo-catalytic properties of two types of composites based on TiO2 – ITO (Indium Tin Oxide and TiO2 – ZnO deposited on conventional ceramic substrates. The samples were characterized by X-ray diffraction (XRD and transmission Electron Microscopy (TEM. The photo-catalytic test was carried out under UV light in order to reduce/oxidize a typical textile dye (Cibacron Yellow. The experiment was carried out in a bench scale reactor using a solution having a known initial dye concentration. After optimization, we found that both nanocomposites exhibit better photocatalytic activity compared to the standard photocatalyst P25 TiO2.

  2. ??????????? ??????????????? ????? ??????-???????? ????????????? ?????????? ??????? ?aO?Al2O3?TiO2 ??? ???????? ?????? ?????

    OpenAIRE

    ???????, ????; ??????, ?????????

    2011-01-01

    ? ????? ?????? ?????????? ???????? ?????????????? ??????????? ????????????? ??? ??????-????????? ???????????????? ?????????? ??????? ?aO?Al2O3?TiO2, ?? ???????? ??????? ? ???????????? ??????? ??? ???????? ? ?????? ????????? ?????? ?????. ???????? ?????????? ???????? ??? ??????????? ?????????? ??????? ????????? ???????????? ?????????? ??? ??????????? 12000?, ?? ????????? ?????????????? ????????????? ???????, ????????? ???? ? ?????????? ????? ???????? ??????? ???????????. ????????, ?? ?? ...

  3. Facile Preparation of TiO2 Nanobranch/Nanoparticle Hybrid Architecture with Enhanced Light Harvesting Properties for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Ju Seong Kim

    2015-01-01

    Full Text Available We report TiO2 nanobranches/nanoparticles (NBN hybrid architectures that can be synthesized by a facile solution phase method. The hybrid architecture simultaneously improves light harvesting and charge collection performances for a dye-sensitized solar cell. First, TiO2 nanorods with a trunk length of 2 μm were grown on a fluorine-doped tin oxide (FTO/glass substrate, and then nanobranches and nanoparticles were deposited on the nanorods’ trunks through a solution method using an aqueous TiCl3 solution at 80°C. The relative amount of nanobranches and nanoparticles can be controlled by multiplying the number of TiCl3 treatments to maximize the amount of surface area. We found that the resultant TiO2 NBN hybrid architecture greatly improves the amount of dye adsorption (five times compared to bare nanorods due to the enhanced surface area, while maintaining a fast charge collection, leading to a three times higher current density and thus tripling the maximum power conversion efficiency for a dye-sensitized solar cell.

  4. Thermal degradation of TiO2 nanotubes on titanium

    Science.gov (United States)

    Shivaram, Anish; Bose, Susmita; Bandyopadhyay, Amit

    2014-10-01

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

  5. Single-crystalline self-branched anatase titania nanowires for dye-sensitized solar cells

    Science.gov (United States)

    Li, Zhenquan; Yang, Huang; Wu, Fei; Fu, Jianxun; Wang, Linjun; Yang, Weiguang

    2017-03-01

    The morphology of the anatase titania plays an important role in improving the photovoltaic performance in dye-sensitized solar cells. In this work, single-crystalline self-branched anatase TiO2 nanowires have been synthesized by hydrothermal method using TBAH and CTAB as morphology controlling agents. The obtained self-branched TiO2 nanowires dominated by a large percentage of (010) facets. The photovoltaic conversion efficiency (6.37%) of dye-sensitized solar cell (DSSC) based on the self-branched TiO2 nanowires shows a significant improvement (26.6%) compared to that of P25 TiO2 (5.03%). The enhanced performance of the self-branched TiO2 nanowires-based DSSC is due to heir large percent of exposed (010) facets which have strong dye adsorption capacity and effective charge transport of the self-branched 1D nanostructures.

  6. Improve photovoltaic performance of titanium dioxide nanorods based dye-sensitized solar cells by Ca-doping

    International Nuclear Information System (INIS)

    Li, Weixin; Yang, Junyou; Zhang, Jiaqi; Gao, Sheng; Luo, Yubo; Liu, Ming

    2014-01-01

    Highlights: • TiO 2 nanorods doped with Ca ions were synthesized by one-step hydrothermal method. • The flat band edge of rutile TiO 2 shifted positively via Ca-doping. • The photoelectric conversion efficiency of dye-sensitized solar cells (DSSCs) based on TiO 2 electrode was much enhanced by Ca-doping. • A relatively high open circuit voltage was obtained by adopting Ca-doped TiO 2 nanorods electrode. - Abstract: Ca-doped TiO 2 nanorod arrays were prepared via the one-step hydrothermal method successfully, and the effect of Ca ions content on the photovoltaic conversion efficiency of dye-sensitized solar cells has been fully discussed in the paper. Although no obvious change on the microstructure and morphology was observed by field emission scanning electron microscope and transmission electron microscope for the Ca-doped samples, the results of X-ray diffraction and X-ray photoelectron spectroscopy confirmed that Ti 4+ was substituted with Ca 2+ successfully. UV–vis spectroscopy results revealed that the flat band edge shifted positively by Ca ions doping. The photovoltaic conversion efficiency of the dye-sensitized solar cells based on the 2 mol% Ca-doped TiO 2 electrode was 43% higher than that of the undoped one due to the less recombination possibility

  7. Synthesis of titanate, TiO2 (B), and anatase TiO2 nanofibers from natural rutile sand

    International Nuclear Information System (INIS)

    Pavasupree, Sorapong; Suzuki, Yoshikazu; Yoshikawa, Susumu; Kawahata, Ryoji

    2005-01-01

    Titanate nanofibers were synthesized by hydrothermal method (150 deg. C for 72 h) using natural rutile sand as the starting materials. TiO 2 (B) and anatase TiO 2 (high crystallinity) nanofibers with the diameters of 20-100 nm and the lengths of 10-100 μm were obtained by calcined titanate nanofibers for 4 h at 400 and 700 deg. C (in air), respectively. The samples characterized by XRD, SEM, TEM, SAED, HRTEM, and BET surface area. This synthesis method provides a simple route to fabricate one-dimensional nanostructured TiO 2 from low cost material. -- Graphical abstract: Titanate nanofibers (b) were synthesized by hydrothermal method (150 deg. C for 72 h) using natural rutile sand (a) as the starting materials. TiO 2 (B) (c) and anatase TiO 2 (d) nanofibers with the diameters of 20-50 nm and the lengths of 10-100 μm were obtained by calcined titanate nanofibers for 4 h at 400 deg. C and 700 deg. C (in air), respectively

  8. Effect of TiO2 on the Gas Sensing Features of TiO2/PANi Nanocomposites

    Directory of Open Access Journals (Sweden)

    Duong Ngoc Huyen

    2011-02-01

    Full Text Available A nanocomposite of titanium dioxide (TiO2 and polyaniline (PANi was synthesized by in-situ chemical polymerization using aniline (ANi monomer and TiCl4 as precursors. SEM pictures show that the nanocomposite was created in the form of long PANi chains decorated with TiO2 nanoparticles. FTIR, Raman and UV-Vis spectra reveal that the PANi component undergoes an electronic structure modification as a result of the TiO2 and PANi interaction. The electrical resistor of the nanocomposite is highly sensitive to oxygen and NH3 gas, accounting for the physical adsorption of these gases. A nanocomposite with around 55% TiO2 shows an oxygen sensitivity of 600–700%, 20–25 times higher than that of neat PANi. The n-p contacts between TiO2 nanoparticles and PANi matrix give rise to variety of shallow donors and acceptor levels in the PANi band gap which enhance the physical adsorption of gas molecules.

  9. Facile synthesis of CdS@TiO2 core–shell nanorods with controllable shell thickness and enhanced photocatalytic activity under visible light irradiation

    International Nuclear Information System (INIS)

    Dong, Wenhao; Pan, Feng; Xu, Leilei; Zheng, Minrui; Sow, Chorng Haur; Wu, Kai; Xu, Guo Qin

    2015-01-01

    Graphical abstract: - Highlights: • CdS nanorods were coated with amorphous TiO 2 shells under a mild condition. • The TiO 2 shell thickness can be controlled from 3.5 to 40 nm. • CdS@TiO 2 nanorods exhibit enhanced photocatalytic activities under visible light. • Efficient charge carriers separation leads to the improved photocatalytic activity. - Abstract: Amorphous TiO 2 layers with a controllable thickness from 3.5 to 40 nm were coated on the one-dimensional CdS nanorods surface under mild conditions. Compared to the bare CdS nanorods, the as-prepared CdS@TiO 2 nanorods exhibit enhanced photocatalytic activities for phenol photodecomposition under visible light irradiation. The improved photoactivity is ascribed to the efficient separation of photogenerated electron and hole charge carriers between CdS cores and TiO 2 shells. This study promises a simple approach to fabricating CdS@TiO 2 core–shell structure nanocomposites, and can be applied for other semiconductor cores with TiO 2 shells

  10. High rate flame synthesis of highly crystalline iron oxide nanorods

    International Nuclear Information System (INIS)

    Merchan-Merchan, W; Taylor, A M; Saveliev, A V

    2008-01-01

    Single-step flame synthesis of iron oxide nanorods is performed using iron probes inserted into an opposed-flow methane oxy-flame. The high temperature reacting environment of the flame tends to convert elemental iron into a high density layer of iron oxide nanorods. The diameters of the iron oxide nanorods vary from 10 to 100 nm with a typical length of a few microns. The structural characterization performed shows that nanorods possess a highly ordered crystalline structure with parameters corresponding to cubic magnetite (Fe 3 O 4 ) with the [100] direction oriented along the nanorod axis. Structural variations of straight nanorods such as bends, and T-branched and Y-branched shapes are frequently observed within the nanomaterials formed, opening pathways for synthesis of multidimensional, interconnected networks

  11. Study of titania nanorod films deposited by matrix-assisted pulsed laser evaporation as a function of laser fluence

    Science.gov (United States)

    Caricato, A. P.; Belviso, M. R.; Catalano, M.; Cesaria, M.; Cozzoli, P. D.; Luches, A.; Manera, M. G.; Martino, M.; Rella, R.; Taurino, A.

    2011-11-01

    Chemically synthesized brookite titanium dioxide (TiO2) nanorods with average diameter and length dimensions of 3-4 nm and 35-50 nm, respectively, were deposited by the matrix-assisted pulsed laser evaporation technique. A toluene nanorod solution was frozen at the liquid-nitrogen temperature and irradiated with a KrF excimer laser ( λ=248 nm, τ=20 ns) at the repetition rate of 10 Hz, at different fluences (25 to 350 mJ/cm2). The deposited films were structurally characterized by high-resolution scanning and transmission electron microscopy. single-crystal Si wafers and carbon-coated Cu grids were used as substrates. Structural analyses evidenced the occurrence of brookite-phase crystalline nanospheres coexisting with individually distinguishable TiO2 nanorods in the films deposited at fluences varying from 50 to 350 mJ/cm2. Nanostructured TiO2 films comprising only nanorods were deposited by lowering the laser fluence to 25 mJ/cm2. The observed shape and phase transitions of the nanorods are discussed taking into account the laser-induced heating effects, reduced melting temperature and size-dependent thermodynamic stability of nanoscale TiO2.

  12. Photocatalytic Degradation of Methylene Blue under UV Light Irradiation on Prepared Carbonaceous TiO2

    Directory of Open Access Journals (Sweden)

    Zatil Amali Che Ramli

    2014-01-01

    Full Text Available This study involves the investigation of altering the photocatalytic activity of TiO2 using composite materials. Three different forms of modified TiO2, namely, TiO2/activated carbon (AC, TiO2/carbon (C, and TiO2/PANi, were compared. The TiO2/carbon composite was obtained by pyrolysis of TiO2/PANi prepared by in situ polymerization method, while the TiO2/activated carbon (TiO2/AC was obtained after treating TiO2/carbon with 1.0 M KOH solution, followed by calcination at a temperature of 450°C. X-ray powder diffraction (XRD, transmission electron microscopy (TEM, Fourier transform infrared (FTIR, thermogravimetric analysis (TG-DTA, Brunauer-Emmet-Teller (BET, and UV-Vis spectroscopy were used to characterize and evaluate the prepared samples. The specific surface area was determined to be in the following order: TiO2/AC > TiO2/C > TiO2/PANi > TiO2 (179 > 134 > 54 > 9 m2 g−1. The evaluation of photocatalytic performance for the degradation of methylene blue under UV light irradiation was also of the same order, with 98 > 84.7 > 69% conversion rate, which is likely to be attributed to the porosity and synergistic effect in the prepared samples.

  13. Fabrication of graphene/titanium carbide nanorod arrays for chemical sensor application

    International Nuclear Information System (INIS)

    Fu, Chong; Li, Mingji; Li, Hongji; Li, Cuiping; Qu, Changqing; Yang, Baohe

    2017-01-01

    Vertically stacked graphene nanosheet/titanium carbide nanorod array/titanium (graphene/TiC nanorod array) wires were fabricated using a direct current arc plasma jet chemical vapor deposition (DC arc plasma jet CVD) method. The graphene/TiC nanorod arrays were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction spectroscopy. The TiO 2 nanotube array was reduced to the TiC nanorod array, and using those TiC nanorods as nucleation sites, the vertical graphene layer was formed on the TiC nanorod surface. The multi-target response mechanisms of the graphene/TiC nanorod array were investigated for ascorbic acid (AA), dopamine (DA), uric acid (UA), and hydrochlorothiazide (HCTZ). The vertically stacked graphene sheets facilitated the electron transfer and reactant transport with a unique porous surface, high surface area, and high electron transport network of CVD graphene sheets. The TiC nanorod array facilitated the electron transfer and firmly held the graphene layer. Thus, the graphene/TiC nanorod arrays could simultaneously respond to trace biomarkers and antihypertensive drugs. - Highlights: • Vertical graphene sheets were prepared with Ti as the catalyst via a CVD method. • TiO 2 nanotubes were key transition layers in the formation of the TiC nanorods. • Vertical growth mechanism of graphene products was discussed. • Biomolecules were detected to be a chemical sensor. • Response mechanism for analytes at the graphene/TiC nanorod array was discussed.

  14. Sulphur doped nanoparticles of TiO2

    Czech Academy of Sciences Publication Activity Database

    Szatmáry, Lórant; Bakardjieva, Snejana; Šubrt, Jan; Bezdička, Petr; Jirkovský, Jaromír; Bastl, Zdeněk; Brezová, V.; Korenko, M.

    2011-01-01

    Roč. 161, č. 1 (2011), s. 23-28 ISSN 0920-5861 R&D Projects: GA MŠk 1M0577 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z40320502 Keywords : photocatalyst * S-doped TiO2 * Thiourea Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.407, year: 2011

  15. Impedance spectroscopy studies of surface engineered TiO2 ...

    Indian Academy of Sciences (India)

    Administrator

    Impedance; nanoTiO2; self-assembled monolayers; electrical resistivity; permittivity. 1. Introduction ... search studies showed that nanostructured TiO2 ceramics possess ..... tion handbook (ed) J Cazes (New York: Marcel Dekker). 3rd ed, p ...

  16. Supercritical Flow Synthesis of TiO2

    DEFF Research Database (Denmark)

    Hellstern, Henrik Christian; Becker, Jacob; Hald, Peter

    2014-01-01

    A new, up-scaled supercritical flow synthesis apparatus has been constructed in Aarhus. A module based system allows for a range of parameter studies with improved parameter control. The dual-reactor setup enables both single phase and core-shell nanoparticle synthesis. TiO2 is a well-known mater...

  17. Fluoropolymer - TiO2 coatings and their superhydrophilicity

    DEFF Research Database (Denmark)

    Søgaard, Erik Gydesen; Simonsen, Morten Enggrob; Jepsen, Henrik

    In this work the superhydrophilicity of coatings on fluoropolymer were investigated. The different coatings were prepared by help of P25 Degussa TiO2 powder, titaniumisopropoxide, Lumiflon® and two different curing agents (BL 3175 and Cymel 303). The investigations were performed by help of a sta...

  18. High-pressure polymorphs of anatase TiO2

    DEFF Research Database (Denmark)

    Arlt, T.; Bermejo, M.; Blanco, M. A.

    2000-01-01

    The equation of state of anatase TiO2 has been determined experimentally-using polycrystalline as well as single-crystal material-and compared with theoretical calculations using the ab initio perturbed ion model. The results are highly consistent, the zero-pressure bulk modulus being 179(2) GPa ...

  19. Protein Corona Prevents TiO2 Phototoxicity.

    Directory of Open Access Journals (Sweden)

    Maja Garvas

    Full Text Available TiO2 nanoparticles have generally low toxicity in the in vitro systems although some toxicity is expected to originate in the TiO2-associated photo-generated radical production, which can however be modulated by the radical trapping ability of the serum proteins. To explore the role of serum proteins in the phototoxicity of the TiO2 nanoparticles we measure viability of the exposed cells depending on the nanoparticle and serum protein concentrations.Fluorescence and spin trapping EPR spectroscopy reveal that the ratio between the nanoparticle and protein concentrations determines the amount of the nanoparticles' surface which is not covered by the serum proteins and is proportional to the amount of photo-induced radicals. Phototoxicity thus becomes substantial only at the protein concentration being too low to completely coat the nanotubes' surface.These results imply that TiO2 nanoparticles should be applied with ligands such as proteins when phototoxic effects are not desired - for example in cosmetics industry. On the other hand, the nanoparticles should be used in serum free medium or any other ligand free medium, when phototoxic effects are desired - as for efficient photodynamic cancer therapy.

  20. TiO2--a prototypical memristive material.

    Science.gov (United States)

    Szot, K; Rogala, M; Speier, W; Klusek, Z; Besmehn, A; Waser, R

    2011-06-24

    Redox-based memristive switching has been observed in many binary transition metal oxides and related compounds. Since, on the one hand, many recent reports utilize TiO(2) for their studies of the memristive phenomenon and, on the other hand, there is a long history of the electronic structure and the crystallographic structure of TiO(2) under the impact of reduction and oxidation processes, we selected this material as a prototypical material to provide deeper insight into the mechanisms behind memristive switching. In part I, we briefly outline the results of the historical and recent studies of electroforming and resistive switching of TiO(2)-based cells. We describe the (tiny) stoichiometrical range for TiO(2 - x) as a homogeneous compound, the aggregation of point defects (oxygen vacancies) into extended defects, and the formation of the various Magnéli phases. Furthermore, we discuss the driving forces for these solid-state reactions from the thermodynamical point of view. In part II, we provide new experimental details about the hierarchical transformation of TiO(2) single crystals into Magnéli phases, and vice versa, under the influence of chemical, electrical and thermal gradients, on the basis of the macroscopic and nanoscopic measurements. Those include thermogravimetry, high-temperature x-ray diffraction (XRD), high-temperature conductivity measurements, as well as low-energy electron diffraction (LEED), x-ray photoelectron spectroscopy (XPS), and LC-AFM (atomic force microscope equipped with a conducting tip) studies. Conclusions are drawn concerning the relevant parameters that need to be controlled in order to tailor the memristive properties.

  1. Characteristics of zinc oxide nanorod array/titanium oxide film heterojunction prepared by aqueous solution deposition

    Science.gov (United States)

    Lee, Ming-Kwei; Hong, Min-Hsuan; Li, Bo-Wei

    2016-07-01

    The characteristics of a ZnO nanorod array/TiO2 film heterojunction were investigated. A TiO2 film was prepared on glass by aqueous solution deposition with precursors of ammonium hexafluorotitanate and boric acid at 40 °C. Then, a ZnO seed layer was prepared on a TiO2 film/glass substrate by RF sputtering. A vertically oriented ZnO nanorod array was grown on a ZnO seed layer/TiO2 film/glass substrate by aqueous solution deposition with precursors of zinc nitrate and hexamethylenetetramine (HMT) at 70 °C. After thermal annealing in N2O ambient at 300 °C, this heterojunction used as an oxygen gas sensor shows much better rise time, decay time, and on/off current ratio than as-grown and annealed ZnO nanorods.

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

    Science.gov (United States)

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    TiO 2 nanotubes (TNT) crystallized at different temperatures were loaded with WO 3 hydrate through the reaction between (NH 4 ) 6 W 7 O 24 ·6H 2 O 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 WO 3 /TiO 2 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. (paper)

  4. Synthesis and nanostructural investigation of TiO2 nanorods doped ...

    Indian Academy of Sciences (India)

    demonstrate that mixed silicon metal oxides enhance the photocatalytic performance due to improved .... investigate the morphology of the nanoparticles. .... Two issues affect the rod structures: (1) Diffusion of adatoms into the matrix at higher.

  5. Interspace modification of titania-nanorod arrays for efficient mesoscopic perovskite solar cells

    International Nuclear Information System (INIS)

    Chen, Peng; Jin, Zhixin; Wang, Yinglin; Wang, Meiqi; Chen, Shixin; Zhang, Yang; Wang, Lingling; Zhang, Xintong; Liu, Yichun

    2017-01-01

    Highlights: • The fabrication of perovskite solar cells utilizing TiO_2 NR arrays. • Investigation of the interspace effect of TiO_2 NR on perovskite layer. • Understanding of the balance between perovskite capping layer and pore filling. - Abstract: Morphology of electron transport layers (ETLs) has an important influence on the device architecture and electronic processes of mesostructured solar cells. In this work, we thoroughly investigated the effect of the interspace of TiO_2 nanorod (NR) arrays on the photovoltaic performance of the perovskite solar cells (PSCs). Along with the interspace in TiO_2-NR arrays increasing, the thickness as well as the crystal size of perovskite capping layer are reduced accordingly, and the filling of perovskite in the channel becomes incomplete. Electrochemical impedance spectroscopy measurements reveal that this variation of perovskite absorber layer, induced by interspace of TiO_2 NR arrays, causes the change of charge recombination process at the TiO_2/perovskite interface, suggesting that a balance between capping layer and the perovskite filling is critical to obtain high charge collection efficiency of PSCs. A power conversion efficiency of 10.3% could be achieved through careful optimization of interspace in TiO_2-NR arrays. Our research will shed light on the morphology control of ETLs with 1D structure for heterojunction solar cells fabricated by solution-deposited method.

  6. Fate of pristine TiO2 nanoparticles and aged paint-containing TiO2 nanoparticles in lettuce crop after foliar exposure.

    Science.gov (United States)

    Larue, Camille; Castillo-Michel, Hiram; Sobanska, Sophie; Trcera, Nicolas; Sorieul, Stéphanie; Cécillon, Lauric; Ouerdane, Laurent; Legros, Samuel; Sarret, Géraldine

    2014-05-30

    Engineered TiO2 nanoparticles (TiO2-NPs) are present in a large variety of consumer products, and are produced in largest amount. The building industry is a major sector using TiO2-NPs, especially in paints. The fate of NPs after their release in the environment is still largely unknown, and their possible transfer in plants and subsequent impacts have not been studied in detail. The foliar transfer pathway is even less understood than the root pathway. In this study, lettuces were exposed to pristine TiO2-NPs and aged paint leachate containing TiO2-NPs and microparticles (TiO2-MPs). Internalization and in situ speciation of Ti were investigated by a combination of microscopic and spectroscopic techniques. Not only TiO2-NPs pristine and from aged paints, but also TiO2-MPs were internalized in lettuce leaves, and observed in all types of tissues. No change in speciation was noticed, but an organic coating of TiO2-NPs is likely. Phytotoxicity markers were tested for plants exposed to pristine TiO2-NPs. No acute phytotoxicity was observed; variations were only observed in glutathione and phytochelatin levels but remained low as compared to typical values. These results obtained on the foliar uptake mechanisms of nano- and microparticles are important in the perspective of risk assessment of atmospheric contaminations. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Favorable recycling photocatalyst TiO2/CFA: Effects of loading percent of TiO2 on the structural property and photocatalytic activity

    International Nuclear Information System (INIS)

    Shi Jianwen; Chen Shaohua; Ye Zhilong; Wang Shumei; Wu Peng

    2010-01-01

    A series of photocatalysts TiO 2 /CFA were prepared using coal fly ash (CFA), waste discharged from coal-fired power plant, as substrate, and then these photocatalysts were characterized by scanning electron microscope, X-ray diffraction analysis, nitrogen adsorption test and ultraviolet-visible absorption analysis. The effects of loading percent of TiO 2 on the photocatalytic activity and re-use property of TiO 2 /CFA were evaluated by the photocatalytic decoloration and mineralization of methyl orange solution. The results show that the pore volume and the specific surface area of the TiO 2 /CFA both increased with the increase in the loading percent of TiO 2 , which improved the photocatalytic activity of TiO 2 /CFA. However, when the loading percent of TiO 2 was too high (up to 54.51%), superfluous TiO 2 was easy to break away from CFA in the course of water treatment, which was disadvantaged to the recycling property of TiO 2 /CFA. In this study, the optimal loading percent of TiO 2 was 49.97%, and the efficiencies of photocatalytic decoloration and mineralization could be maintained above 99% and 90%, respectively, when the photocatalyst was used repeatedly, without any decline, even at the sixth cycle.

  8. Superhydrophilicity of TiO2 nano thin films

    International Nuclear Information System (INIS)

    Mohammadizadeh, M.R.; Ashkarran, A.A.

    2007-01-01

    Full text: Among the several oxide semiconductors, titanium dioxide has a more helpful role in our environmental purification due to its photocatalytic activity, photo-induced superhydrophilicity, and as a result of them non-toxicity, self cleaning, and antifogging effects. After the discovery of superhydrophilicity of titanium dioxide in 1997, several researches have been performed due to its nature and useful applications. The superhydrophilicity property of the surface allows water to spread completely across the surface rather than remains as droplets, thus making the surface antifog and easy-to-clean. The distinction of photo-induced catalytic and hydrophilicity properties of TiO 2 thin films has been accepted although, the origin of hydrophilicity property has not been recognized completely yet. TiO 2 thin films on soda lime glass were prepared by the sol-gel method and spin coating process. The calcination temperature was changed from 100 to 550 C. XRD patterns show increasing the content of polycrystalline anatase phase with increasing the calcination temperature. The AFM results indicate granular morphology of the films, which particle size changes from 22 to 166 nm by increasing the calcination temperature. The RBS, EDX and Raman spectroscopy of the films show the ratio of Ti:O∼0.5, and diffusion of sodium ions from substrate into the layer, by increasing the calcination temperature. The UV/Vis. spectroscopy of the films indicates a red shift by increasing the calcination temperature. The contact angle meter experiment shows that superhydrophilicity of the films depends on the formation of anatase crystal structure and diffused sodium content from substrate to the layer. The best hydrophilicity property was observed at 450 C calcination temperature, where the film is converted to a superhydrophilic surface after 10 minutes under 2mW/cm 2 UV irradiation. TiO 2 thin film on Si(111), Si(100), and quartz substrates needs less time to be converted to superhydrophilic surface rather than glass and polycrystalline Si substrates. Our results are consistent with the idea that UV-induced wetting of TiO 2 surface is caused by the removal of hydrophobic layers of hydrocarbons by TiO 2 -mediated photo-oxidation, which leads to the attractive interaction of water with clean TiO 2 surface. (authors)

  9. Dye-sensitized solar cells based on nanoparticle-decorated ZnO/TiO2 core/shell nanorod arrays

    International Nuclear Information System (INIS)

    Wang Meili; Huang Changgang; Cao Yongge; Deng Zhonghua; Liu Yuan; Huang Zhi; Huang Jiquan; Huang Qiufeng; Guo Wang; Liang Jingkui; Yu Qingjiang

    2009-01-01

    Nanoparticles (NPs) decorated ZnO/TiO 2 core/shell nanorod arrays were fabricated on transparent conductive glass substrates by sequential plasma deposition and post-annealing processes for dye-sensitized solar cells (DSSCs) applications. The NPs decorated ZnO/TiO 2 nanorods were composed of single-crystalline ZnO nanorods, homogeneously coated thin TiO 2 shells and entirely covered anatase TiO 2 NPs. The photocurrent density of the composite electrode was largely enhanced due to the enlarged surface area, the dark current was suppressed and the open-circuit voltage was increased because of the energy barrier formed at the interface between the ZnO core and the TiO 2 shell. The increased photocurrent and open-circuit voltage led to an improvement of twice the energy conversion efficiency.

  10. The TiO2 Hierarchical Structure with Nanosheet Spheres for Improved Photoelectric Performance in Dye-Sensitized Solar Cells

    Science.gov (United States)

    Yin, Xin; Guan, Yingli; Song, Lixin; Xie, Xueyao; Du, Pingfan; Xiong, Jie

    2018-04-01

    A bi-layer photoanode is successfully fabricated for dye-sensitized solar cells (DSSCs) composed of P25/TiO2 nanorod (P25/TNR) as the underlayer and TiO2 nanosheet spheres (TNSs) as the light-scattering layer. Notably, the P25-TNR provides multiple functions, including more dye loading, more efficient charge transport and a lower electron recombination rate for the photoanode. Besides, the unique structure of TNS can significantly improve the light-harvesting capacity, boosting the light-harvesting efficiency. Therefore, an enhanced short-circuit current and power conversion efficiency of 18.04 mA cm-2 and 5.99%, respectively, were achieved for the P25/TNR-TNS-based DSSC, which was better than that of the P25-TNS-based (15.17 mA cm-2, 5.36%) and bare TNS-based (11.43 mA cm-2, 4.14%) DSSCs. This indicates that this bi-layer structure effectively combines the advantages of the one-dimensional (1D) nanostructure and three-dimensional (3D) hierarchical structure. In short, this work demonstrates the possibility of fabricating desirable photoanodes for high-performance DSSCs by rational design of nanostructures and effective combination of multi-functional components.

  11. Effects of low pressure plasma treatments on DSSCs based on rutile TiO2 array photoanodes

    International Nuclear Information System (INIS)

    Wang, Weiqi; Chen, Jiazang; Luo, Jianqiang; Zhang, Yuzhi; Gao, Lian; Liu, Yangqiao; Sun, Jing

    2015-01-01

    Graphical abstract: - Highlights: • Plasma treatment effects on rutile nanorod arrays studied. • Dye adsorption amount increased by all plasma treatment. • Flat-band potential positively shifted after NP and OP treatments. • Cell performance improved by NP and OP treatments. - Abstract: In this paper, three types of low pressure plasma including hydrogen (HP), oxygen (OP) and nitrogen (NP) treatments have been utilized for the first time to improve DSSCs based on rutile TiO 2 array photoanodes. Their effects on the photoanodes and the cell performance have been systematically compared by characterizing the dye loading amount, flat-band potential, donor concentration, electron lifetime and the photovoltaic parameters. Experimental results show that all the three plasma treatments increase the dye loading owing to improved hydrophilicity or enhanced surface roughness. It is found that NP and OP treatments significantly increase the TiO 2 donor concentration and decrease trapping sites. By this way, the electron transport is enhanced and the electron recombination is effectively restrained. These comprehensive effects make NP and OP treatments beneficial for the overall performance, by which 13% and 5% increases in efficiency are achieved. However, HP treatment causes obvious reduction in the donor concentration and more severe electron recombination, which decreases the efficiency by about 15%

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-07-01

    Full text: One-dimensional nanostructures have been intensively studied, from the point of view of their synthesis and mechanisms of formation, as well as their applications in photonics, solar energy conversion, environmental and photocatalysis, since their properties due high surface area, electrical conductivity and light dispersion effects. Titanium dioxide (TiO2) nanoparticles have been demonstrated to be an effective multifunctional material especially when the particle size is less than 50 nm exhibit photoinduced activities that originate from the semiconductor band gap. TiO2 is semiconductor more used in photocatalysis, for this reason various properties have been thoroughly investigated in order to show that the photocatalytic activity and TiO2 reaction mechanism are influenced by structure, defects and impurities, surface morphology. and interfaces in addition to the concentration of dopants, such as rare-earth elements. Cerium ions, for example, vary between Ce4+ and Ce3 + oxidation state making the cerium oxide appear as CeO2 and Ce2O3 under oxidation and reduction conditions. These different electronic structures of Ce3+ (4f15d0) and Ce4+ (4f05d0) provide different catalytic and optical properties at the TiO2. In this work, samples of Ce-doped TiO2 and TiO2 were synthesized by alkali route, and its photocatalytic activity analyzed in order to create a relationship between the response obtained and the structure and morphology of each sample. Alkali route consists in submitting TiO2 (anatase) powder directly in medium of the NaOH (10M) and maintained at 120°C/20 hours by a glycerin bath with subsequent washed with water and HCl (0.1M) until reaching the desired pH. The synthesized samples were then studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The photocatalytic decomposition of rhodamine B (Rh.B) it was performed under UV irradiation and visible light in air. For the obtained samples with pH 7, XRD measurements showed the coexistence of TiO2 and sodium titanate phase. By decreasing the pH during acid washing the sodium content was eliminated leaving only the main phase. This behavior was observed for samples containing Cerium concentrations up to 0.2%. The obtained nanotubes presented multiple walls, having dimensions of 5 nm of diameter and about 200 nm of length. Energy dispersive X-ray spectroscopy analyzes revealed that nanotubes are mainly composed of titanium and oxygen, with small amounts of sodium when pH is 7 and sodium no was observed for the sample obtained at pH 4. It shows that synthesis conditions are very important in order to obtain single-phase structures. In addition, TiO2 nanotubes showed good photocatalytic activity with degradation around 100 minutes.(author)

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    Full text: One-dimensional nanostructures have been intensively studied, from the point of view of their synthesis and mechanisms of formation, as well as their applications in photonics, solar energy conversion, environmental and photocatalysis, since their properties due high surface area, electrical conductivity and light dispersion effects. Titanium dioxide (TiO2) nanoparticles have been demonstrated to be an effective multifunctional material especially when the particle size is less than 50 nm exhibit photoinduced activities that originate from the semiconductor band gap. TiO2 is semiconductor more used in photocatalysis, for this reason various properties have been thoroughly investigated in order to show that the photocatalytic activity and TiO2 reaction mechanism are influenced by structure, defects and impurities, surface morphology. and interfaces in addition to the concentration of dopants, such as rare-earth elements. Cerium ions, for example, vary between Ce4+ and Ce3 + oxidation state making the cerium oxide appear as CeO2 and Ce2O3 under oxidation and reduction conditions. These different electronic structures of Ce3+ (4f15d0) and Ce4+ (4f05d0) provide different catalytic and optical properties at the TiO2. In this work, samples of Ce-doped TiO2 and TiO2 were synthesized by alkali route, and its photocatalytic activity analyzed in order to create a relationship between the response obtained and the structure and morphology of each sample. Alkali route consists in submitting TiO2 (anatase) powder directly in medium of the NaOH (10M) and maintained at 120°C/20 hours by a glycerin bath with subsequent washed with water and HCl (0.1M) until reaching the desired pH. The synthesized samples were then studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The photocatalytic decomposition of rhodamine B (Rh.B) it was performed under UV irradiation and visible light in air. For the obtained samples with pH 7, XRD measurements showed the coexistence of TiO2 and sodium titanate phase. By decreasing the pH during acid washing the sodium content was eliminated leaving only the main phase. This behavior was observed for samples containing Cerium concentrations up to 0.2%. The obtained nanotubes presented multiple walls, having dimensions of 5 nm of diameter and about 200 nm of length. Energy dispersive X-ray spectroscopy analyzes revealed that nanotubes are mainly composed of titanium and oxygen, with small amounts of sodium when pH is 7 and sodium no was observed for the sample obtained at pH 4. It shows that synthesis conditions are very important in order to obtain single-phase structures. In addition, TiO2 nanotubes showed good photocatalytic activity with degradation around 100 minutes.(author)

  14. Photocorrosion Mechanism of TiO2-Coated Photoanodes

    Directory of Open Access Journals (Sweden)

    Arjen Didden

    2015-01-01

    Full Text Available Atomic layer deposition was used to coat CdS photoanodes with 7 nm thick TiO2 films to protect them from photocorrosion during photoelectrochemical water splitting. Photoelectrochemical measurements indicate that the TiO2 coating does not provide full protection against photocorrosion. The degradation of the film initiates from small pinholes and shows oscillatory behavior that can be explained by an Avrami-type model for photocorrosion that is halfway between 2D and 3D etching. XPS analysis of corroded films indicates that a thin layer of CdS remains present on the surface of the corroded photoanode that is more resilient towards photocorrosion.

  15. Application of TIO2 as A sorbent for radioactive waste

    International Nuclear Information System (INIS)

    Zamroni, H.; Las, T.; Kamarz, H.

    1997-01-01

    The sorption properties of the neodymium has been studied by using TiO 2 sorbent. The experiment was carried out by batch methods to investigate the kinetic sorption, effect of pH and effect of NaNO 3 concentration in the solution. Neodymium uses for a model of trivalent actinide treated by TiO 2 which was known as materials having high thermal and radiation stabilities as well as potentially used for immobilization of waste with cement or vitrification. the results show that the optimum of kinetic sorption was obtained after one day experiment to reach the equilibrium in sorption on pH 4, and the increasing of NaNO 3 concentrations will increase the sorption of neodymium in solution (author)

  16. TiO2 and SiC nanostructured films, organized CNT structures

    Indian Academy of Sciences (India)

    sized nanostructured TiO2 films through hydrolysis of titanium tetra-isopropoxide. (TTIP) [9 ... structured TiO2 as a photocatalyst is as follows [15]:. TiO2(ns) ... The deposited films were easily detached from the silica tube and subjected to. SEM.

  17. Enhanced Bonding of Silver Nanoparticles on Oxidized TiO2(110)

    DEFF Research Database (Denmark)

    Hansen, Jonas Ørbæk; Salazar, Estephania Lira; Galliker, Patrick

    2010-01-01

    The nucleation and growth of silver nanoclusters on TiO2(110) surfaces with on-top O adatoms (oxidized TiO2), surface O vacancies and H adatoms (reduced TiO2) have been studied. From the interplay of scanning tunneling microscopy/photoelectron spectroscopy experiments and density functional theor...

  18. Photocatalytic Water Treatment on TiO2 Thin Layers.

    Czech Academy of Sciences Publication Activity Database

    Šolcová, Olga; Spáčilová, L.; Maléterová, Ywetta; Morozová, Magdalena; Ezechiáš, Martin; Křesinová, Zdena

    2016-01-01

    Roč. 57, č. 25 (2016), s. 11631-11638 ISSN 1944-3994. [International Conference on Protection and Restoration of the Environment /12./. Skiathos Island, 29.06.2014-03.07.2014] R&D Projects: GA TA ČR TA01020804 Institutional support: RVO:67985858 ; RVO:61388971 Keywords : water purification * endocrine disruptor * photocatalytic * TiO2 layers Subject RIV: CI - Industrial Chemistry, Chemical Engineering; EE - Microbiology, Virology (MBU-M) Impact factor: 1.631, year: 2016

  19. TiO(2)-graphene nanocomposite as high performace photocatalysts

    Czech Academy of Sciences Publication Activity Database

    Štengl, Václav; Popelková, Daniela; Vláčil, P.

    2011-01-01

    Roč. 115, č. 51 (2011), s. 25209-25218 ISSN 1932-7447 R&D Projects: GA MPO(CZ) FI-IM3/061; GA MPO FI-IM5/239 Institutional research plan: CEZ:AV0Z40320502 Keywords : titanium-dioxide * visible-light * doped TiO2 * degradation * graphene * oxide Subject RIV: CA - Inorganic Chemistry Impact factor: 4.805, year: 2011

  20. Defects improved photocatalytic ability of TiO2

    International Nuclear Information System (INIS)

    Li, Lei; Tian, Hong-Wei; Meng, Fan-Ling; Hu, Xiao-Ying; Zheng, Wei-Tao; Sun, Chang Q.

    2014-01-01

    Highlights: • Defect improves the photocatalytic ability by band gap narrowing and carrier life prolonging. • Atomic undercoordination shortens the local bonds, entraps, and polarizes electrons. • Polarization lowers the local workfunction and lengthens carrier life. • Entrapment and polarization narrows the band gap tuning the wavelength of absorption. - Abstract: Defect generation forms an important means modulating the photocatalytic ability of TiO 2 with mechanisms that remain yet unclear. Here we show that a spectral distillation clarifies the impact of defect on modulating the band gap, electroaffinity, and work function of the substance. Firstly, by analyzing XPS measurements, we calibrated the 2p 3/2 level of 451.47 eV for an isolated Ti atom and its shifts by 2.14 and 6.94 eV, respectively, upon Ti and TiO 2 bulk formation. Spectral difference between the defected and the un-defected TiO 2 skin revealed then that the 2p 3/2 level shifts further from 6.94 to 9.67 eV due to the defect-induced quantum entrapment. This entrapment is associated with an elevation of the upper edges of both the 2p 3/2 and the conduction band by polarization. The shortening and strengthening of bonds between undercoordinated atoms densify and entrap the core electrons, which in turn polarize the dangling bond electrons of defect atoms. The entrapment and polarization mediate thus the band gap, the electroaffinity, the work function, and the photocatalytic ability of TiO 2

  1. Versatile preparation method for mesoporous TiO2 electrodes ...

    Indian Academy of Sciences (India)

    Unknown

    cyanate into CuI layer further enhanced the efficiency up to 2⋅75% under the irradiance .... an extremely easy way to dope films with virtually any .... to see the effect of ionic liquid on CuI, 1-ethyl-3-methyl- ... This analysis showed that TiO2 electrodes were polycrys- .... thin insulating layer of Al2O3 by using dip-coating meth-.

  2. Drug loading of nanoporous TiO2 films

    International Nuclear Information System (INIS)

    Ayon, Arturo A; Cantu, Michael; Chava, Kalpana; Agrawal, C Mauli; Feldman, Marc D; Johnson, Dave; Patel, Devang; Marton, Denes; Shi, Emily

    2006-01-01

    The loading of therapeutic amounts of drug on a nanoporous TiO 2 surface is described. This novel drug-loading scheme on a biocompatible surface, when employed on medical implants, will benefit patients who require the deployment of drug-eluting implants. Anticoagulants, analgesics and antibiotics can be considered on the associated implants for drug delivery during the time of maximal pain or risk for patients undergoing orthopedic procedures. Therefore, this scheme will maximize the chances of patient recovery. (communication)

  3. Lattice defects in rutile, TiO2

    International Nuclear Information System (INIS)

    Nakagawa, M.; Itoh, H.; Nakanishi, S.; Kondo, K.; Okada, M.; Atobe, K.

    1991-01-01

    Rutile, TiO 2 , having a relatively high melting point exhibits strong optical absorption after neutron irradiation (8 x 10 16 n f /cm 2 ) at 15K. The band peak is located near 0.96 μ, having a FWHM of 0.87 eV (at liquid nitrogen temperature). After inverse recovery at 120K, lattice defects due probably to F centers are annealed out at about 220K. (author)

  4. Pyrrole-regulated precipitation of titania nanorods on polymer fabrics for photocatalytic degradation of trace toluene in air

    Science.gov (United States)

    Gu, Yi-Jie; Wen, Wei; Xu, Yang; Wu, Jin-Ming

    2018-03-01

    When compared with nanoparticulate counterparts, TiO2 thin films with vertically aligned one-dimensional (1D) nanostructures exhibit enhanced photocatalytic activity because of the highly accessible surface area. The perpendicular of the 1D nanostructure reduces the charge migration path and hence the carrier recombination rate, which also contributes to the photocatalytic activity. Furthermore, TiO2 thin films on flexible substrates are more suitable to degrade pollutants in either water or air because of its easy recovery and free-bending shape. In this study, flexible polyethylene fabrics were firstly coated with a sol-gel nanoparticulate TiO2 seed layer. Quasi-aligned TiO2 nanorods were then precipitated homogeneously under an atmospheric pressure and a low temperature not exceeding 80 °C, using a peroxy-titanium complex precursor with the additive of pyrrole. It is found that the density of TiO2 nanorods increased with the increasing amount of pyrrole monomers. The resultant TiO2 film on polyethylene fabrics exhibited a much reduced band gap of ca. 2.86 eV, which can be attributed to the surface oxygen deficiencies. When utilized to assist photocatalytic degradation of trace toluene in air under the UV light illumination, the TiO2 film exhibited a gradually increased photocatalytic activity upon the increasing cycles for up to six, because of the gradual removal of trace organics on the TiO2 surface. The highest photocatalytic efficiency is recorded to be 5 times that of TiO2 nanotube arrays, which are regarded as an excellent photocatalyst for air cleaning.

  5. Microporous TiO2-WO3/TiO2 films with visible-light photocatalytic activity synthesized by micro arc oxidation and DC magnetron sputtering

    International Nuclear Information System (INIS)

    Wu, Kee-Rong; Hung, Chung-Hsuang; Yeh, Chung-Wei; Wu, Jiing-Kae

    2012-01-01

    Highlights: ► A simple MAO is used to prepare porous WO 3 /TiO 2 layer on Ti sheet as a visible-light enabled catalyst. ► The photocatalytic activity of the WO 3 /TiO 2 is enhanced by sputtering over an N,C-TiO 2 layer. ► This is ascribed to the synergetic effect of hybrid sample prepared by two-step method. - Abstract: This study reports the preparation of microporous TiO 2 -WO 3 /TiO 2 films with a high surface area using a two-step approach. A porous WO 3 /TiO 2 template was synthesized by oxidizing a titanium sheet using a micro arc oxidation (MAO) process. This sheet was subsequently overlaid with a visible light (Vis)-enabled TiO 2 (N,C-TiO 2 ) film, which was deposited by codoping nitrogen (N) and carbon (C) ions into a TiO 2 lattice using direct current magnetron sputtering. The resulting microporous TiO 2 -WO 3 /TiO 2 film with a 0.38-μm-thick N,C-TiO 2 top-layer exhibited high photocatalytic activity in methylene blue (MB) degradation among samples under ultraviolet (UV) and Vis irradiation. This is attributable to the synergetic effect of two-step preparation method, which provides a highly porous microstructure and the well-crystallized N,C-TiO 2 top-layer. This is because a higher surface area with high crystallinity favors the adsorption of more MB molecules and more photocatalytic active areas. Thus, the microporous TiO 2 -WO 3 /TiO 2 film has promising applications in the photocatalytic degradation of dye solution under UV and Vis irradiation. These results imply that the microporous WO 3 /TiO 2 can be used as a template of hybrid electrode because it enables rapid fabrication.

  6. Sensing and electrical properties of TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Usman, M.

    2011-01-01

    The purpose of this work was to synthesize TiO 2 nanoparticles using Coprecipitation method. 2 different samples were synthesized, one with a modifier and other without using a modifier. After synthesis, newly formed nanoparticles were characterized b different techniques to find various properties of these nanoparticles. Scanning electron Microscopy (SEM) was used to study structure and morphology of Cu nanoparticles and for compositional analysis Energy dispersive spectroscopy (EDS) was used. X-Ray Diffraction (XRD) Studies were also carried out to find phase an average particle Size. To find the band gap of our nanoparticles, UV-Visible Spectroscopy was also done. Non-Modified nanoparticles were as small as 12nm reported by SEM images which were synthesized using a modifier were as small as 10nm. Modified TiO 2 nanoparticles were used in humidity sensing devices and it properties as a humidity sensor were examined by doing Impedance spectroscopy, D measurements and Dielectric measurements. Our TiO 2 humidity sensor showed sensitivity for humidity at low and mid-range frequencies while its response time was 4 seconds when we changed RH% to 90 from 40% and measured the impedance. (author)

  7. Incorporation of chromium into TiO2 nanopowders

    International Nuclear Information System (INIS)

    Kollbek, Kamila; Sikora, Marcin; Kapusta, Czesław; Szlachetko, Jakub; Radecka, Marta; Lyson-Sypien, Barbara; Zakrzewska, Katarzyna

    2015-01-01

    Highlights: • Nanopowders of TiO 2 :Cr with different amount of Cr dopant were obtained by flame spray synthesis, FSS. • Increase in the optical absorption and a shift of the absorption edge were observed upon Cr doping. • HERFD-XANES measurements indicated that the average valence state of titanium ions was preserved. • Increasing magnetic susceptibility of a paramagnetic character was observed upon Cr doping. - Abstract: The paper reports on the results of a study of optical, electronic and magnetic properties of TiO 2 nanopowders doped with Cr ions. Diffused reflectance spectra reveal an increase in the optical absorption and a shift of the absorption edge towards lower energies upon Cr doping. Direct information on the Ti electronic state and the symmetry of its nearest environment is obtained from XANES Ti K-edge spectra. Magnetic behaviour is probed by means of the temperature dependence of DC magnetic susceptibility. Increasing magnetic susceptibility of a paramagnetic character is observed upon increasing chromium doping. The Curie constant of TiO 2 :10 at.% Cr sample (0.12 emu K/mol Oe) is lower than that expected for Cr 3+ (0.1875 emu K/mol Oe) possibly due to the appearance of Cr 4+ or the presence of the orbital contribution to the magnetic moment

  8. Sol-gel synthesis of TiO2 nanoparticles and photocatalytic degradation of methyl orange in aqueous TiO2 suspensions

    International Nuclear Information System (INIS)

    Yang Huaming; Zhang Ke; Shi Rongrong; Li Xianwei; Dong Xiaodan; Yu Yongmei

    2006-01-01

    Anatase TiO 2 nanoparticles of about 16 nm in crystal size have been successfully synthesized via a sol-gel method. Thermal treatment of the precursor at 500-600 deg. C results in the formation of different TiO 2 phase compositions. The samples were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Effects of the pH value of the solution, H 2 O 2 addition, TiO 2 phase composition and recycled TiO 2 on the photocatalytic degradation of methyl orange (MeO) in TiO 2 suspensions under ultraviolet (UV) illumination were primarily investigated. The results indicate that a low pH value, proper amount of H 2 O 2 and pure anatase TiO 2 will facilitate the photocatalytic oxidation of the MeO solution. The photodegradation degree decreases with increasing the pH value of the solution and varies with different amounts of H 2 O 2 . Pure anatase TiO 2 shows better photocatalytic activity for MeO decolorization than biphase TiO 2 . The photocatalytic mechanism of the as-synthesized TiO 2 nanoparticles was discussed

  9. OXIDACIÓN DE p -NITROFENOL USANDO TiO 2 -ADENOSINA MONOFOSFATO I OXIDATION OF p -NITROPHENOL USING TiO 2 -ADENOSIN MONOPHOSPHATE

    Directory of Open Access Journals (Sweden)

    Carlos F. Rivas

    2018-04-01

    Full Text Available The surface of TiO2 was modified with the nucleotides adenosine 3’-monophosphate (AMP’3 and Adenosine 5’-monophosphate (AMP’5. The adsorption of nucleotides was adjusted to Langmuir ́s adsorption model, determining that the optimal condition for TiO 2 modification was at neutral pH. UV-Visible Diffuse Reflectance and IR Attenuated Total Reflectance spectra show that the chemisorption of nucleotides take placed on TiO 2 anatase. The new catalysts (TiO 2 -nucleotide improved the photodegradation of p -nitrophenol in a wide range of pH as compared with the titanium dioxide precursor. Most photoactivity was generated by using the new photocatalytic in the degradation of p -nitrophenol at pH = 6, obtaining high values for the pseudo first order kinetic constant (0.0254 min -1 and 0.0244 min -1 for TiO 2 -AMP’3 and TiO 2 -AMP’5, respectively. For all pH, the trend obtained for the photodegradation was: TiO 2 -AMP ́3 @ TiO 2 -AMP’5 > TiO 2 . Langmuir-Hinshelwood kinetics shows that the contribution of the surface reac tion rate governs the oxidation of the contaminant.

  10. Photocatalytic effects for the TiO2-coated phosphor materials

    International Nuclear Information System (INIS)

    Yoon, Jin-Ho; Jung, Sang-Chul; Kim, Jung-Sik

    2011-01-01

    Research highlights: → The photocatalytic behavior of the coupling of TiO 2 with phosphorescent materials. → The photobleaching of an MB aqueous solution under visible light irradiation. → The ALD TiO 2 -coated phosphor composite showed much higher photocatalytic reactivity. → The light emitted from the phosphors contributed to the photo-generation. - Abstract: This study investigated the photocatalytic behavior of the coupling of TiO 2 with phosphorescent materials. A TiO 2 thin film was deposited on CaAl 2 O 4 :Eu 2+ ,Nd 3+ phosphor particles by using atomic layer deposition (ALD), and its photocatalytic reaction was investigated by the photobleaching of an aqueous solution of methylene-blue (MB) under visible light irradiation. To clarify the mechanism of the TiO 2 -phosphorescent materials, two different samples of TiO 2 -coated phosphor and TiO 2 -Al 2 O 3 -coated phosphor particles were prepared. The photocatalytic mechanisms of the ALD TiO 2 -coated phosphor powders were different from those of the pure TiO 2 and TiO 2 -Al 2 O 3 -coated phosphor. The absorbance in a solution of the ALD TiO 2 -coated phosphor decreased much faster than that of pure TiO 2 under visible irradiation. In addition, the ALD TiO 2 -coated phosphor showed moderately higher photocatalytic degradation of MB solution than the TiO 2 -Al 2 O 3 -coated phosphor did. The TiO 2 -coated phosphorescent materials were characterized by transmission electron microscopy (TEM), Auger electron spectroscopy (AES) and X-ray photon spectroscopy (XPS).

  11. Synthesis of nanostructured TiO2 (anatase) and TiO2(B) in ionic liquids

    Czech Academy of Sciences Publication Activity Database

    Mansfeldová, Věra; Lásková, Barbora; Krýsová, Hana; Zukalová, Markéta; Kavan, Ladislav

    2014-01-01

    Roč. 230, JUL 2014 (2014), s. 85-90 ISSN 0920-5861 R&D Projects: GA ČR GA13-07724S; GA MŠk 7E09117 Grant - others:European Commission(XE) NMP-229036 Institutional support: RVO:61388955 Keywords : TiO2(B) * ionic liquid * electrochemistry Subject RIV: CG - Electrochemistry Impact factor: 3.893, year: 2014

  12. Phase transformation synthesis of TiO2/CdS heterojunction film with high visible-light photoelectrochemical activity

    Science.gov (United States)

    Liu, Canjun; Yang, Yahui; Li, Jie; Chen, Shu

    2018-06-01

    CdS/TiO2 heterojunction film used as a photoanode has attracted much attention in the past few years due to its good visible light photocatalytic activity. However, CdS/TiO2 films prepared by conventional methods (successive ionic layer adsorption and reaction, chemical bath deposition and electrodeposition) show numerous grain boundaries in the CdS layer and an imperfect contact at the heterojunction interface. In this study, we designed a phase transformation method to fabricate CdS/TiO2 nanorod heterojunction films. The characterization results showed that the CdS layer with fewer grain boundaries was conformally coated on the TiO2 nanorod surface and the formation mechanism has been explained in this manuscript. Moreover, the prepared CdS/TiO2 films show a high photocatalytic activity and the photocurrent density is as high as 9.65 mA cm‑2 at 0.80 V versus RHE. It may be attributed to fewer grain boundaries and a compact heterojunction contact, which can effectively improve charge separation and transportation.

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

    Science.gov (United States)

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

    2013-01-01

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

  14. High pressure structural phase transitions of TiO2 nanomaterials

    International Nuclear Information System (INIS)

    Li Quan-Jun; Liu Bing-Bing

    2016-01-01

    Recently, the high pressure study on the TiO 2 nanomaterials has attracted considerable attention due to the typical crystal structure and the fascinating properties of TiO 2 with nanoscale sizes. In this paper, we briefly review the recent progress in the high pressure phase transitions of TiO 2 nanomaterials. We discuss the size effects and morphology effects on the high pressure phase transitions of TiO 2 nanomaterials with different particle sizes, morphologies, and microstructures. Several typical pressure-induced structural phase transitions in TiO 2 nanomaterials are presented, including size-dependent phase transition selectivity in nanoparticles, morphology-tuned phase transition in nanowires, nanosheets, and nanoporous materials, and pressure-induced amorphization (PIA) and polyamorphism in ultrafine nanoparticles and TiO 2 -B nanoribbons. Various TiO 2 nanostructural materials with high pressure structures are prepared successfully by high pressure treatment of the corresponding crystal nanomaterials, such as amorphous TiO 2 nanoribbons, α -PbO 2 -type TiO 2 nanowires, nanosheets, and nanoporous materials. These studies suggest that the high pressure phase transitions of TiO 2 nanomaterials depend on the nanosize, morphology, interface energy, and microstructure. The diversity of high pressure behaviors of TiO 2 nanomaterials provides a new insight into the properties of nanomaterials, and paves a way for preparing new nanomaterials with novel high pressure structures and properties for various applications. (topical review)

  15. Improving the photovoltaic performance of the all-solid-state TiO2 NR/CuInS2 solar cell by hydrogen plasma treatment

    Science.gov (United States)

    Chen, Bingfeng; Niu, Wenzhe; Lou, Zirui; Ye, Zhizhen; Zhu, Liping

    2018-07-01

    The interfacial properties of the heterojunction between p-type and n-type materials play an important role in the performance of the solar cell. In this paper, a p-type CuInS2 film was deposited on TiO2 nanorod arrays by spin coating to fabricate an all-solid-state solar cell and the TiO2 nanorod arrays were treated with hydrogen plasma(H:TiO2) to ameliorate the interfacial properties. The influence of the hydrogen plasma treatment on the performance of the solar cell was investigated. The short-circuit current density was obviously raised and the power conversion efficiency of the solar cell improved to 0.30%, which is three times that of solar cells without hydrogen plasma treatment. The enhancement of the performance is attributed to not only the enhancement of carrier separation and transport, but the reduction of the recombination of electrons and holes, which is caused by hydrogen plasma treatment.

  16. Improving the photovoltaic performance of the all-solid-state TiO2 NR/CuInS2 solar cell by hydrogen plasma treatment.

    Science.gov (United States)

    Chen, Bingfeng; Niu, Wenzhe; Lou, Zirui; Ye, Zhizhen; Zhu, Liping

    2018-07-06

    The interfacial properties of the heterojunction between p-type and n-type materials play an important role in the performance of the solar cell. In this paper, a p-type CuInS 2 film was deposited on TiO 2 nanorod arrays by spin coating to fabricate an all-solid-state solar cell and the TiO 2 nanorod arrays were treated with hydrogen plasma(H:TiO 2 ) to ameliorate the interfacial properties. The influence of the hydrogen plasma treatment on the performance of the solar cell was investigated. The short-circuit current density was obviously raised and the power conversion efficiency of the solar cell improved to 0.30%, which is three times that of solar cells without hydrogen plasma treatment. The enhancement of the performance is attributed to not only the enhancement of carrier separation and transport, but the reduction of the recombination of electrons and holes, which is caused by hydrogen plasma treatment.

  17. Low temperature fabrication of perovskite solar cells with TiO2 nanoparticle layers

    International Nuclear Information System (INIS)

    Kanayama, Masato; Oku, Takeo; Suzuki, Atsushi; Yamada, Masahiro; Sakamoto, Hiroki; Minami, Satoshi; Kohno, Kazufumi

    2016-01-01

    TiO 2 /CH 3 NH 3 PbI 3 -based photovoltaic devices were fabricated by a spin-coating method using a mixture solution. TiO 2 require high-temperature processing to achieve suitably high carrier mobility. TiO 2 electron transport layers and TiO 2 scaffold layers for the perovskite were fabricated from TiO 2 nanoparticles with different grain sizes. The photovoltaic properties and microstructures of solar cells were characterized. Nanoparticle sizes of these TiO 2 were 23 nm and 3 nm and the performance of solar cells was improved by combination of two TiO 2 nanoparticles

  18. Photocatalytic decouloration of malachite green dye by application of TiO2 nanotubes

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  19. First-principles atomistic Wulff constructions for an equilibrium rutile TiO2 shape modeling

    Science.gov (United States)

    Jiang, Fengzhou; Yang, Lei; Zhou, Dali; He, Gang; Zhou, Jiabei; Wang, Fanhou; Chen, Zhi-Gang

    2018-04-01

    Identifying the exposed surfaces of rutile TiO2 crystal is crucial for its industry application and surface engineering. In this study, the shape of the rutile TiO2 was constructed by applying equilibrium thermodynamics of TiO2 crystals via first-principles density functional theory (DFT) and Wulff principles. From the DFT calculations, the surface energies of six low-index stoichiometric facets of TiO2 are determined after the calibrations of crystal structure. And then, combined surface energy calculations and Wulff principles, a geometric model of equilibrium rutile TiO2 is built up, which is coherent with the typical morphology of fully-developed equilibrium TiO2 crystal. This study provides fundamental theoretical guidance for the surface analysis and surface modification of the rutile TiO2-based materials from experimental research to industry manufacturing.

  20. Composition of Surface Adsorbed Layer of TiO2 Stored in Ambient Air

    Directory of Open Access Journals (Sweden)

    Zakharenko V.S.

    2017-11-01

    Full Text Available The processes of dark, UV, and visible light promoted desorption of surface species were investigated for three different TiO2 samples: TiO2 prepared by dispersion of the titania single crystal, TiO2 prepared by combustion of a pyrotechnic mixture in air, and commercial TiO2 P25. The composition of the adsorbed layer was identified in the dark and under UV and visible light irradiation. The composition of desorption products showed the dependence of the adsorption layer state on the TiO2 nature. Methane photodesorption was detected only for the commercial TiO2 P25. Possible reasons for methane emission include the capturing of complete molecules during the TiO2 production process and photocatalytic hydrogenation of CO2 under UV-light.

  1. Immobilization of TiO2 nanoparticles on Fe-filled carbon nanocapsules for photocatalytic applications

    International Nuclear Information System (INIS)

    Huang, H.-C.; Huang, G.-L.; Chen, H.-L.; Lee, Y.-D.

    2006-01-01

    Using a simple sol-gel method, a novel magnetic photocatalyst was produced by immobilization of TiO 2 nano-crystal on Fe-filled carbon nanocapsules (Fe-CNC). High resolution TEM images indicated that the immobilization of TiO 2 on Fe-CNC was driven primarily by heterogeneous coagulation, whereas surface nucleation and growth was the dominant mechanism for immobilizing TiO 2 on acid-functionalized hollow CNC. The TiO 2 immobilized on Fe-CNC exhibited the anatase phase as revealed by the X-ray diffraction (XRD) patterns. In comparison with free TiO 2 and TiO 2 -coated CNC, TiO 2 -coated Fe-CNC displayed good performance in the removal of NO gas under UV exposure. Due to the advantages of easy recycling and good photocatalytic efficiency, the novel magnetic photocatalyst developed here has potential use in photocatalytic applications for pollution prevention

  2. Study of TiO2 nanotubes as an implant application

    International Nuclear Information System (INIS)

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

    2016-01-01

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

  3. N-doped hollow urchin-like anatase TiO2@C composite as a novel anode for Li-ion batteries

    Science.gov (United States)

    Xing, Yalan; Wang, Shengbin; Fang, Baizeng; Song, Ge; Wilkinson, David P.; Zhang, Shichao

    2018-05-01

    N-doped hollow urchin-like anatase TiO2 spheres (HUTSs) with carbon coating (HUTS@C) are prepared through a facile and scalable hydrothermal reaction followed by coating of polypyrrole and carbonization. The HUTS is composed of radially grown anatase nanorods and possesses an enhanced percentage of exposed {001} facets compared with P25 TiO2 nanoparticles. After the carbon coating, the HUTS@C retains the hollow nanostructure although covered with an N-doped carbon layer. As an anode for Li-ion batteries, the HUTS@C delivers a higher capacity of 165.1 mAh g-1 at 1C after 200 cycles and better rate capability (111.7 mAh g-1 at 10C) than the HUTS. Further electrochemical studies reveal that the HUTS@C has a better electrochemical reversibility, lower charge-transfer resistance, and higher Li-ion diffusion coefficient due to its unique nanosctructure including the hollow core, anatase phase of TiO2 microspheres with high exposed {001} facets and the N-doped carbon layer, which facilitates mass transport and enhances electrical conductivity.

  4. The preparation, surface structure, zeta potential, surface charge density and photocatalytic activity of TiO2 nanostructures of different shapes

    International Nuclear Information System (INIS)

    Grover, Inderpreet Singh; Singh, Satnam; Pal, Bonamali

    2013-01-01

    Titania based nanocatalysts such as sodium titanates of different morphology having superior surface properties are getting wide importance in photocatalysis research. Despite having sodium (Na) contents and its high temperature synthesis (that generally deteriorate the photoreactivity), these Na-titanates often exhibit better photoactivity than P25-TiO 2 catalyst. Hence, this work demonstrated the influence of crystal structure, BET surface area, surface charge, zeta potential (ζ) and metal loading on the photocatalytic activity of as-prepared sodium titanate nanotube (TNT) and titania nanorod (TNR). Straw like hollow orthorhombic-TNT (Na 2 Ti 2 O 5 ·H 2 O) particles (W = 9–12 nm and L = 82–115 nm) and rice like pure anatase-TNR particles (W = 8–13 nm and L = 81–134 nm) are obtained by the hydrothermal treatment of P25-TiO 2 with NaOH, which in fact, altered the net surface charge of TNT and TNR particles. The observed ζ = −2.82 (P25-TiO 2 ), −13.5 (TNT) and −22.5 mV (TNR) are significantly altered by the Ag and Cu deposition. It has been found here that TNT displayed best photocatalytic activity for the imidacloprid insecticide (C 9 H 10 ClN 5 O 2 ) degradation to CO 2 formation under UV irradiation because of its largest surface area 176 m 2 g −1 among the catalysts studied.

  5. The preparation, surface structure, zeta potential, surface charge density and photocatalytic activity of TiO2 nanostructures of different shapes

    Science.gov (United States)

    Grover, Inderpreet Singh; Singh, Satnam; Pal, Bonamali

    2013-09-01

    Titania based nanocatalysts such as sodium titanates of different morphology having superior surface properties are getting wide importance in photocatalysis research. Despite having sodium (Na) contents and its high temperature synthesis (that generally deteriorate the photoreactivity), these Na-titanates often exhibit better photoactivity than P25-TiO2 catalyst. Hence, this work demonstrated the influence of crystal structure, BET surface area, surface charge, zeta potential (ζ) and metal loading on the photocatalytic activity of as-prepared sodium titanate nanotube (TNT) and titania nanorod (TNR). Straw like hollow orthorhombic-TNT (Na2Ti2O5·H2O) particles (W = 9-12 nm and L = 82-115 nm) and rice like pure anatase-TNR particles (W = 8-13 nm and L = 81-134 nm) are obtained by the hydrothermal treatment of P25-TiO2 with NaOH, which in fact, altered the net surface charge of TNT and TNR particles. The observed ζ = -2.82 (P25-TiO2), -13.5 (TNT) and -22.5 mV (TNR) are significantly altered by the Ag and Cu deposition. It has been found here that TNT displayed best photocatalytic activity for the imidacloprid insecticide (C9H10ClN5O2) degradation to CO2 formation under UV irradiation because of its largest surface area 176 m2 g-1 among the catalysts studied.

  6. Optical Properties and Surface Morphology of Nano-composite PMMA: TiO2 Thin Films

    International Nuclear Information System (INIS)

    Lyly Nyl Ismail; Ahmad Fairoz Aziz; Habibah Zulkefle

    2011-01-01

    There are two nano-composite PMMA: TiO 2 solutions were prepared in this research. First solution is nano-composite PMMA commercially available TiO 2 nanopowder and the second solution is nano-composite PMMA with self-prepared TiO 2 powder. The self-prepared TiO 2 powder is obtained by preparing the TiO 2 sol-gel. Solvo thermal method were used to dry the TiO 2 sol-gel and obtained TiO 2 crystal. Ball millers were used to grind the TiO 2 crystal in order to obtained nano sized powder. Triton-X was used as surfactant to stabilizer the composite between PMMA: TiO 2 . Besides comparing the nano-composite solution, we also studied the effect of the thin films thickness on the optical properties and surface morphology of the thin films. The thin films were deposited by sol-gel spin coating method on glass substrates. The optical properties and surface characterization were measured with UV-VIS spectrometer equipment and atomic force microscopy (AFM). The result showed that nano-composite PMMA with self prepared TiO 2 give high optical transparency than nano-composite PMMA with commercially available TiO 2 nano powder. The results also indicate as the thickness is increased the optical transparency are decreased. Both AFM images showed that the agglomerations of TiO 2 particles are occurred on the thin films and the surface roughness is increased when the thickness is increased. High agglomeration particles exist in the AFM images for nano-composite PMMA: TiO 2 with TiO 2 nano powder compare to the other nano-composite solution. (author)

  7. Distinct toxic interactions of TiO2 nanoparticles with four coexisting organochlorine contaminants on algae.

    Science.gov (United States)

    Zhang, Shuai; Deng, Rui; Lin, Daohui; Wu, Fengchang

    Engineered nanoparticles are increasingly discharged into the environment. After discharge, these nanoparticles can interact with co-existing organic contaminants, resulting in a phenomena referred to as 'joint toxicity'. This study evaluated joint toxicities of TiO 2 nanoparticles (TiO 2 NPs) with four different (atrazine, hexachlorobenzene, pentachlorobenzene, and 3,3',4,4'-tetrachlorobiphenyl) organochlorine contaminants (OCs) toward algae (Chlorella pyrenoidosa). The potential mechanisms underlying the joint toxicity were discussed, including TiO 2 NPs-OC interactions, effects of TiO 2 NPs and OCs on biophysicochemical properties of algae and effects of TiO 2 NPs and OCs on each other's bioaccumulation in algae. The results indicate that coexposure led to a synergistic effect on the joint toxicity for TiO 2 NPs-atrazine, antagonistic effect for TiO 2 NPs-hexachlorobenzene and TiO 2 NPs-3,3',4,4'-tetrachlorobiphenyl, and an additive effect for TiO 2 NPs-pentachlorobenzene. There was nearly no adsorption of OCs by TiO 2 NPs, and the physicochemical properties of TiO 2 NPs were largely unaltered by the presence of OCs. However, both OCs and NPs affected the biophysicochemical properties of algal cells and thereby influenced the cell surface binding and/or internalization. TiO 2 NPs significantly increased the bioaccumulation of each OC. However, with the exception of atrazine, the bioaccumulation of TiO 2 NPs decreased when used with each OC. The distinct joint toxicity outcomes were a result of the balance between the increased toxicities of OCs (increased bioaccumulations) and the altered toxicity of TiO 2 NPs (bioaccumulation can either increase or decrease). These results can significantly improve our understanding of the potential environmental risks associated with NPs.

  8. Hybrid matrices of TiO2 and TiO2–Ag nanofibers with silicone for high water flux photocatalytic degradation of dairy effluent

    DEFF Research Database (Denmark)

    Kanjwal, Muzafar Ahmad; Alm, Martin; Thomsen, Peter

    2016-01-01

    TiO2 and TiO2–Ag nanofibers were produced by electrospinning technique and surface coated on silicone elastomer (diameter: 10.0 mm; thickness: 2.0 mm) by dipcoating method. These coated hybrid nanoporous matrices were characterized by various morphological and physicochemical techniques (like SEM...

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

    KAUST Repository

    Shi, Le

    2015-01-01

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

  10. Charge transfer between biogenic jarosite derived Fe3+and TiO2 enhances visible light photocatalytic activity of TiO2.

    Science.gov (United States)

    Chowdhury, Mahabubur; Shoko, Sipiwe; Cummings, Fransciuos; Fester, Veruscha; Ojumu, Tunde Victor

    2017-04-01

    In this work, we have shown that mining waste derived Fe 3+ can be used to enhance the photocatalytic activity of TiO 2 . This will allow us to harness a waste product from the mines, and utilize it to enhance TiO 2 photocatalytic waste water treatment efficiency. An organic linker mediated route was utilized to create a composite of TiO 2 and biogenic jarosite. Evidence of FeOTi bonding in the TiO 2 /jarosite composite was apparent from the FTIR, EFTEM, EELS and ELNEFS analysis. The as prepared material showed enhanced photocatalytic activity compared to pristine TiO 2 , biogenic jarosite and mechanically mixed sample of jarosite and TiO 2 under both simulated and natural solar irradiation. The prepared material can reduce the electrical energy consumption by 4 times compared to pristine P25 for degradation of organic pollutant in water. The material also showed good recyclability. Results obtained from sedimentation experiments showed that the larger sized jarosite material provided the surface to TiO 2 nanoparticles, which increases the settling rate of the materials. This allowed simple and efficient recovery of the catalyst from the reaction system after completion of photocatalysis. Enhanced photocatalytic activity of the composite material was due to effective charge transfer between TiO 2 and jarosite derived Fe 3+ as was shown from the EELS and ELNEFS. Generation of OH was supported by photoluminesence (PL) experiments. Copyright © 2016. Published by Elsevier B.V.

  11. Structural properties of TiO2 nanomaterials

    Science.gov (United States)

    Kusior, Anna; Banas, Joanna; Trenczek-Zajac, Anita; Zubrzycka, Paulina; Micek-Ilnicka, Anna; Radecka, Marta

    2018-04-01

    The surface of solids is characterized by active, energy-rich sites that determine physicochemical interaction with gaseous and liquid media and possible applications in photocatalysis. The behavior of materials in such processes is related to their form and amount of various species, especially water and forms of oxygen adsorbed on the surface. The preparation of materials with controlled morphology, which includes modifications of the size, geometry, and composition, is currently an important way of optimizing properties, as many of them depend on not only the size and phase composition, but also on shape. Hydroxylated centers on the surface, which can be treated as trapping sites, are particularly significant. Water adsorbed on the surface bridging hydroxyl groups can distinctly modulate the properties of the surface of titania. The saturation of the surface with hydroxyl groups may improve the photocatalytic properties. TiO2 nanomaterials were obtained via different methods. SEM and TEM analysis were performed to study the morphology. The analysis of XRD and Raman data revealed a phase composition of obtained materials. To examine the surface properties, FTIR absorption spectra of TiO2 nanomaterials were recorded. The photocatalytic activity of titanium dioxide nanoparticles was investigated through the decomposition of methylene blue. It was demonstrated that each surface modification affects the amount of adsorbed hydroxyl groups. The different contributions of the two species to the ν(H2O) FTIR bands for different nanostructures result from the preparation conditions. It was noted that pre-adsorbed water (the surface-bridging hydroxyl) might significantly modulate the surface properties of the material. The increase in hydroxyl group density on the titanium dioxide surface enhances the effectiveness of the photocatalytic processes. It was demonstrated that flower-like titania obtained via hydrothermal synthesis exhibits the weakest catalytic activity, in contrast to the typical spherical TiO2.

  12. Structure and properties of nanophase TiO2

    International Nuclear Information System (INIS)

    Siegel, R.W.; Hahn, H.; Ramasamy, S.; Zongquan, Li; Ting, Lu; Gronsky, R.

    1987-07-01

    Ultrafine-grained, nanophase samples of TiO 2 (rutile) were synthesized by the gas-condensation method and subsequent in-situ compaction, and then studied by transmission electron microscopy, Vickers hardness measurements, and positron annihilation spectroscopy as a function of sintering temperature. The nanophase compacts densified rapidly above 500 0 C, with only a small increase in grain size. The hardness values obtained by this method are comparable to or greater than coarser-grained compacts, but at temperatures 400 to 600 0 C lower than conventional sintering temperatures and without the need for sintering aids. 11 refs., 3 figs

  13. On Multiple Zagreb Indices of TiO2 Nanotubes.

    Science.gov (United States)

    Malik, Mehar Ali; Imran, Muhammad

    2015-01-01

    The First and Second Zagreb indices were first introduced by I. Gutman and N. Trinajstic in 1972. It is reported that these indices are useful in the study of anti-inflammatory activities of certain chemical instances, and in elsewhere. Recently, the first and second multiple Zagreb indices of a graph were introduced by Ghorbani and Azimi in 2012. In this paper, we calculate the Zagreb indices and the multiplicative versions of the Zagreb indices of an infinite class of Titania nanotubes TiO(2)[m,n].

  14. Carrier recombination dynamics in anatase TiO 2 nanoparticles

    Science.gov (United States)

    Cavigli, Lucia; Bogani, Franco; Vinattieri, Anna; Cortese, Lorenzo; Colocci, Marcello; Faso, Valentina; Baldi, Giovanni

    2010-11-01

    We present an experimental study of the radiative recombination dynamics in size-controlled TiO 2 nanoparticles in the range 20-130 nm. Time-integrated photoluminescence spectra clearly show a dominance of self-trapped exciton (STE) emission, with main features not dependent on the nanoparticle size and on its environment. From picosecond time-resolved experiments as a function of the excitation density and the nanoparticle size we address the STE recombination dynamics as the result of two main processes related to the direct STE formation and to the indirect STE formation mediated by non-radiative surface states.

  15. Al-bound hole polarons in TiO2

    International Nuclear Information System (INIS)

    Stashans, Arvids; Bermeo, Sthefano

    2009-01-01

    Changes in the structural and electronic properties of TiO 2 (anatase and rutile) due to the Al-doping are studied using a quantum-chemical approach based on the Hartree-Fock theory. The formation of hole polarons trapped at oxygen sites near the Al impurity has been discovered and their spatial configuration are discussed. The occurrence of well-localized one-center hole polarons in rutile may influence its photocatalytic activity. Optical absorption energy for this hole center is obtained, 0.4 eV, using the ΔSCF approach.

  16. Tailoring the wettability of nanocrystalline TiO 2 films

    Science.gov (United States)

    Liang, Qiyu; Chen, Yan; Fan, Yuzun; Hu, Yong; Wu, Yuedong; Zhao, Ziqiang; Meng, Qingbo

    2012-01-01

    The water contact angle (WCA) of nanocrystalline TiO2 films was adjusted by fluoroalkylsilane (FAS) modification and photocatalytic lithography. FAS modification made the surface hydrophobic with the WCA up to ∼156°, while ultraviolet (UV) irradiation changed surface to hydrophilic with the WCA down to ∼0°. Both the hydrophobicity and hydrophilicity were enhanced by surface roughness. The wettability can be tailored by varying the concentration of FAS solution and soaking time, as well as the UV light intensity and irradiation time. Additionally, with the help of photomasks, hydrophobic-hydrophilic micropatterns can be fabricated and manifested via area-selective deposition of polystyrene particles.

  17. Highly uniform bipolar resistive switching characteristics in TiO2/BaTiO3/TiO2 multilayer

    International Nuclear Information System (INIS)

    Ma, W. J.; Zhang, X. Y.; Wang, Ying; Zheng, Yue; Lin, S. P.; Luo, J. M.; Wang, B.; Li, Z. X.

    2013-01-01

    Nanoscale multilayer structure TiO 2 /BaTiO 3 /TiO 2 has been fabricated on Pt/Ti/SiO 2 /Si substrate by chemical solution deposition method. Highly uniform bipolar resistive switching (BRS) characteristics have been observed in Pt/TiO 2 /BaTiO 3 /TiO 2 /Pt cells. Analysis of the current-voltage relationship demonstrates that the space-charge-limited current conduction controlled by the localized oxygen vacancies should be important to the resistive switching behavior. X-ray photoelectron spectroscopy results indicated that oxygen vacancies in TiO 2 play a crucial role in the resistive switching phenomenon and the introduced TiO 2 /BaTiO 3 interfaces result in the high uniformity of bipolar resistive switching characteristics

  18. Photocatalytic activities of heterostructured TiO2-graphene porous microspheres prepared by ultrasonic spray pyrolysis

    International Nuclear Information System (INIS)

    Yang, Jikai; Zhang, Xintong; Li, Bing; Liu, Hong; Sun, Panpan; Wang, Changhua; Wang, Lingling; Liu, Yichun

    2014-01-01

    Highlights: • USP method is used to prepare TiO 2 -graphene porous microspheres. • XPS shows GO sheets in the composites has been reduced to graphene. • TiO 2 -graphene microspheres display a red-shifted absorption edge. • PL spectra indicate graphene can accept the photoexcited electrons from TiO 2 . • TiO 2 -graphene shows higher photocatalytic activity than TiO 2 under solar light. -- Abstract: TiO 2 -graphene porous microspheres were prepared by ultrasonic spray pyrolysis (USP) of aqueous suspension of graphene oxide containing TiO 2 nanoparticles (Degussa P25). The composite microspheres were characterized with SEM, XPS, photoluminescence, Raman and UV–Vis absorption spectra. TiO 2 -graphene porous microspheres displayed higher photocatalytic activity for the degradation of methylene blue solution than pristine TiO 2 microspheres under the irradiation of Xe lamp, and the highest activity was obtained at a weight percentage of graphene around 1%. The effect of graphene on photocatalytic activity of porous microsphere was discussed in terms of the enhanced charge separation by TiO 2 -graphene heterojunction, increased absorption of the visible light, as well as the possible hindrance of mass transportation in microspheres

  19. Photocatalytic Decolorization Study of Methyl Orange by TiO2–Chitosan Nanocomposites

    Directory of Open Access Journals (Sweden)

    Imelda Fajriati

    2014-10-01

    Full Text Available The photocatalytic decolorization of methyl orange (MO by TiO2-chitosan nanocomposite has been studied. This study was started by synthesizing TiO2-chitosan nanocomposites using sol-gel method with various concentrations of Titanium(IV isopropoxide (TTIP as the TiO2 precursor. The structure, surface morphology, thermal and optical property of TiO2-chitosan nanocomposite were characterized by X-ray diffraction (XRD, fourier transform infra red (FTIR spectroscopy, scanning electron microscopy (SEM, thermogravimetric analysis (TGA, and diffuse reflectance ultra violet (DRUV spectroscopy. The photocatalytic activity of TiO2-chitosan nanocomposite was evaluated by photocatalytic decolorization of methyl orange as a model pollutant. The results indicate that the particle size of TiO2 increases with increasing ofthe concentration of TTIP, in which TiO2 with smallest particle size exhibit the highest photocatalytic activity. The highest photocatalytic decolorization was obtained at 5 h of contact time, initial concentration of MO at 20 ppm and at solution pH of 4. Using these conditions, over 90% of MO was able to be decolorized using 0.02 g of TiO2-chitosan nanocomposite under UV light irradiation. The TiO2-chitosan nanocomposite could be reused, which meant that the TiO2-chitosan nanocomposites can be developed as an effective and economical photocatalyst to decolorize or treat dye in wastewater.

  20. The Influence of NiO Addition in TiO2 Structure and Its Photoactivity

    Science.gov (United States)

    Wahyuningsih, S.; Ramelan, A. H.; Purwanti, P. D.; Munawaroh, H.; Ichsan, S.; Kristiawan, Y. R.

    2018-03-01

    The synthesis of TiO2 together with the TiO2-NiO composite using various annealing temperatures has been studied. The synthesis of TiO2 was performed by sol gel method using Titanium Tetra Isopropoxide (TTIP) precursor, whereas the synthesis of TiO2-NiO composite was done by wet impregnation method using NiNO3.6H2O precursor. This study aims to determine the influence of NiO addition in its structure and photoactivity. The diffraction of synthesized TiO2 at 400 °C temperature shows anatase TiO2 peak at 2θ = 25.35 °. The addition of NiO dopant to the synthesis of TiO2 process is carried out by annealing at 300 °C, 400 °C, 500 °C, 600 °C, and 700 °C, respectively. The TiO2-NiO composite has been prepared and shows the diffraction peak of NiO at 2θ=43° about 33.08 to 36.68%. The optimum result of Rhodamine B photodegradation with TiO2 was 43.15%, while the optimum result of Rhodamine B degradation with TiO2-NiO composite was 92.85%.

  1. Preparation of rutile TiO(2) coating by thermal chemical vapor deposition for anticoking applications.

    Science.gov (United States)

    Tang, Shiyun; Wang, Jianli; Zhu, Quan; Chen, Yaoqiang; Li, Xiangyuan

    2014-10-08

    To inhibit the metal catalytic coking and improve the oxidation resistance of TiN coating, rutile TiO2 coating has been directly designed as an efficient anticoking coating for n-hexane pyrolysis. TiO2 coatings were prepared on the inner surface of SS304 tubes by a thermal CVD method under varied temperatures from 650 to 900 °C. The rutile TiO2 coating was obtained by annealing the as-deposited TiO2 coating, which is an alternative route for the deposition of rutile TiO2 coating. The morphology, elemental and phase composition of TiO2 coatings were characterized by SEM, EDX and XRD, respectively. The results show that deposition temperature of TiO2 coatings has a strong effect on the morphology and thickness of as-deposited TiO2 coatings. Fe, Cr and Ni at.% of the substrate gradually changes to 0 when the temperature is increased to 800 °C. The thickness of TiO2 coating is more than 6 μm and uniform by metalloscopy, and the films have a nonstoichiometric composition of Ti3O8 when the deposition temperature is above 800 °C. The anticoking tests show that the TiO2 coating at a deposition temperature of 800 °C is sufficiently thick to cover the cracks and gaps on the surface of blank substrate and cut off the catalytic coke growth effect of the metal substrate. The anticoking ratio of TiO2 coating corresponding to each 5 cm segments is above 65% and the average anticoking ratio of TiO2 coating is up to 76%. Thus, the TiO2 coating can provide a very good protective layer to prevent the substrate from severe coking efficiently.

  2. Exchange of TiO2 nanoparticles between streams and streambeds.

    Science.gov (United States)

    Boncagni, Natalia Ticiana; Otaegui, Justo Manuel; Warner, Evelyn; Curran, Trisha; Ren, Jianhong; de Cortalezzi, Maria Marta Fidalgo

    2009-10-15

    The expanding use of manufactured nanoparticles has increased the potential for their release into the natural environment. Particularly, TiO2 nanoparticles pose significant exposure risk to humans and other living species due to their extensive use in a wide range of fields. To better understand the environmental and health risks associated with the release of TiO2 nanoparticles, knowledge on their fate and transport is needed. This study evaluates the transport of two different TiO2 nanoparticles: one commercially available (P25 TiO2 and the other synthesized at a lab scale (synthesized TiO2). Laboratory flume, column, and batch experiments were conducted to investigate the processes dominating the transport of TiO2 nanoparticles between streams and streambeds and to characterize the properties of these nanoparticles under different physicochemical conditions. Results show that the synthesized TiO2 was more stable compared to the P25 TiO2, which underwent significant aggregation under the same experimental conditions. As a result, P25 TiO2 deposited at a faster rate than the synthesized TiO2 in the streambed. Both types of TiO2 nanoparticles deposited in the streambed were easily released when the stream velocity was increased. The aggregation and deposition of P25 TiO2 were highly dependent on pH. A process-based colloid exchange model was applied to interpret the observed transport behavior of the TiO2 nanoparticles.

  3. Preparation of brookite TiO2 nanoparticles with small sizes and the improved photovoltaic performance of brookite-based dye-sensitized solar cells.

    Science.gov (United States)

    Xu, Jinlei; Wu, Shufang; Jin, Jingpeng; Peng, Tianyou

    2016-11-10

    Brookite TiO 2 nanoparticles with small sizes (hereafter denoted as BTP particles) were synthesized through the hydrothermal treatment of TiCl 4 solution with Pb(NO 3 ) 2 as an additive. The obtained BTP particles have a large specific surface area (∼122.2 m 2 g -1 ) and relatively uniform particle sizes (∼10 nm) with the coexistence of a small quantity of nanorods with a length of ∼100 nm. When used as a photoanode material for dye-sensitized solar cells (DSSCs), the BTP particles show a much higher dye-loading content than the brookite TiO 2 quasi nanocubes (denoted as BTN particles) with a mean size of ∼50 nm and a specific surface area of ∼34.2 m 2 g -1 that were prepared through a similar hydrothermal process but without the addition of Pb(NO 3 ) 2 . The fabricated BTP film-based solar cell with an optimized film thickness gives a conversion efficiency up to 6.36% with a 74% improvement when compared to the BTN film-based one (3.65%) under AM 1.5G one sun irradiation, while the corresponding bilayer brookite-based solar cell by using brookite TiO 2 submicrometer particles as an overlayer of the BTP film displays a significantly enhanced efficiency of 7.64%. Both of them exceed the current record (5.97%) for the conversion efficiency of pure brookite-based DSSCs reported in the literature. The present results not only demonstrate a really simple synthesis of brookite TiO 2 nanoparticles with both high phase purity and a large surface area, but also offer an efficient approach to improve the photovoltaic performance of brookite-based solar cells by offsetting brookite's inherent shortages such as lower dye-loading and poor conductivity as compared to anatase.

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

    KAUST Repository

    Zhang, Zhonghai; Yang, Xiulin; Hedhili, Mohamed N.; Ahmed, Elaf S.; 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 Ti3+ self-doping in TiO2. A hierarchical TiO2 nanotube array with the top layer serving as TiO2 photonic crystals (TiO2 NTPCs

  5. A facile hydrothermal strategy for synthesis of SnO2 nanorods-graphene nanocomposites for high performance photocatalysis.

    Science.gov (United States)

    Chen, Lu-Ya; Zhang, Wei-De; Xu, Bin; Yu, Yu-Xiang

    2012-09-01

    In this study, we report a facilely hydrothermal process for synthesizing SnO2 nanorods-graphene (SnO2 nanorods-GR) composite using graphite oxide and SnCl4 as raw materials. The SnO2 nanorods-GR composite was characterized by X-ray diffraction, electron microscopy, Xray photoelectron spectroscopy, and thermogravimetric analysis. Compared to commercial TiO2 nanoparticles P25 and neat SnO2 nanorods, the SnO2 nanorods-GR composite exhibits higher photocatalytic activity under UV light irradiation. The mechanism of its high photocatalytic activity is mainly ascribed to the synergy effect between SnO2 and graphene, in which graphene acts as an adsorbent and electron acceptor due to its large structure of pi-pi conjugation from sp2 hybrid carbon atoms. The results demonstrated in this study provide a promising way to enhance the photocatalytic activity by compounding semiconductive nanocrystals with graphene.

  6. Photoluminescence studies on Eu doped TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Ningthoujam, R.S.; Sudarsan, V.; Vatsa, R.K.; Kadam, R.M.; Jagannath; Gupta, A.

    2009-01-01

    Eu 3+ doped TiO 2 nanoparticles were prepared by urea hydrolysis in ethylene glycol medium at low temperature of 150 deg. C. X-ray diffraction study showed that anatase phase of tetragonal structure was formed below 500 deg. C; and above this temperature, additional peaks due to rutile phase were also observed. From luminescence study, it was found that as prepared nanoparticles showed the enhanced luminescence intensity due to energy transfer from host to europium ions. However, photoluminescence from these nanoparticles was found to disappear when the samples were heated above 900 deg. C. We established the origin of the reduction in the luminescence intensity from Eu 3+ when doped in TiO 2 and heated at 900 deg. C. Based on detailed studies at different heat-treatment temperatures using techniques such as X-ray diffraction, X-ray photoelectron spectroscopy, electron paramagnetic resonance, Raman spectroscopy, and Moessbauer spectroscopy, it has been established that formation of Eu 2 Ti 2 O 7 phase, wherein Eu 3+ ions occupy high symmetric environment (D 3d ) and also reduced distance between Eu 3+ and Eu 3+ ions is responsible for the decrease/loss in the luminescence intensity.

  7. Unconventional cells of TiO2 doped with erbium

    International Nuclear Information System (INIS)

    Ribeiro, P.C.; Campos, R.D.; Oliveira, A.S.; Wellen, R.; Diniz, V.C.S.; Costa, A.C.F.M. da

    2016-01-01

    The technology used in TiO_2 solar cells is in constant improvement, new configurations have been developed, aiming practicality and leading to efficiency increase of photovoltaic devices. This paper proposes a new technology for the production of solar cells in order to investigate a better utilization of solar spectrum of TiO2 doped with erbium (Er"3"+), proven by energetic conversion. The Ti_0_,_9Er_0_,_1O2 system was obtained by Pechini method. Nanoparticles have a crystallite size 65.30 nm and surface area 118.48 m"2/g. These characteristics are essential for the formation of the film to be deposited on the conductive glass substrate constituting the cell's photoelectrode. The other side of the cell is the platinum counter electrode. The cell will have the faces sealed by a thermoplastic and, finally the electrolyte will be inserted, then they will be electrically evaluated through energy efficiency and confronted with the literature data base. (author)

  8. Fabrication and characterization of TiO2-epoxy nanocomposite

    International Nuclear Information System (INIS)

    Chatterjee, Amit; Islam, Muhammad S.

    2008-01-01

    A systematic study has been conducted to investigate the matrix properties by introducing nanosize TiO 2 (5-40 nm, 0.5-2% by weight) fillers into an epoxy resin. Ultrasonic mixing process, via sonic cavitations, was employed to disperse the particles into the resin system. The thermal, mechanical, morphology and the viscoelastic properties of the nanocomposite and the neat resin were measured with TGA, DMA, TEM and Instron. The nano-particles are dispersed evenly throughout the entire volume of the resin. The nanofiller infusion improves the thermal, mechanical and viscoelastic properties of the epoxy resin. The nanocomposite shows increase in storage modulus, glass transition temperature, tensile modulus, flexural modulus and short beam shear strength from neat epoxy resin. The mechanical performance and thermal stability of the epoxy nanocomposites are depending on with the dispersion state of the TiO 2 in the epoxy matrix and are correlated with loading (0.0015-0.006% by volume). In addition, the nanocomposite shows enhanced flexural strength. Several reasons to explain these effects in terms of reinforcing mechanisms were discussed

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

    Science.gov (United States)

    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. Electrical conductivity characteristic of TiO2 nanowires from hydrothermal method

    International Nuclear Information System (INIS)

    Othman, Mohd Azlishah; Amat, Noor Faridah; Ahmad, Badrul Hisham; Rajan, Jose

    2014-01-01

    One dimensional nanostructures of titanium dioxide (TiO 2 ) were synthesized via hydrothermal method by mixing TiO 2 as precursor in aqueous solution of NaOH as solvent. Then, heat and washing treatment was applied. Thus obtained wires had diameter ∼15 nm. TiO 2 nanowires will be used as a network in solar cell such dye-sensitized solar cell in order to improve the performance of electron movement in the device. To improve the performance of electron movement, the characteristics of TiO 2 nanowires have been analyses using field emission scanning electron microscopy (FESEM) analysis, x-ray diffractometer (XRD) analysis and brunauer emmett teller (BET) analysis. Finally, electrical conductivity of TiO 2 nanowires was determined by measuring the resistance of the TiO 2 nanowires paste on microscope glass.

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

    KAUST Repository

    Zhang, Z.; Wang, Peng

    2012-01-01

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

  12. Reflectance spectroscopy from TiO2 particles embedded in polyurethane

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy; Canulescu, Stela; Johansen, Villads Egede

    2013-01-01

    This paper presents the results of a physical simulation carried out using TiO2-Polyurethane composite coating on bright aluminium surface to understand the light scattering effect for designing white surfaces. Polyurethane matrix is selected due to the matching refractive index (1.7) with Al2O3...... layer on anodized aluminium surfaces. Three different TiO2 particle distributions were dispersed in polyurethane and spin coated onto high gloss and caustic etched aluminium substrates. Reflectance spectra of TiO2-polyurethane films of various concentrations were analysed using an integrating sphere....... The results show that the TiO2-polyurethane coatings have a high diffuse reflectance as a result of multiple scattering from TiO2 particles. Diffuse reflectance spectra of TiO2 containing films vary weakly with particle concentration and reach a steady state value at a concentration of 0.75 wt.%. Using...

  13. Photodegradation of Reactive Golden Yellow R Dye Catalyzed by Effective Titania (TiO2)

    International Nuclear Information System (INIS)

    Bedurus, E.A.; Marinah Mohd Ariffin; Mohd Hasmizam Razali

    2015-01-01

    In the present research, Microwave Assisted Synthesis (MAS) method was applied to synthesize titania (TiO 2 ) at 150 degree Celsius in a range of 2-6 hours heating time. Each prepared TiO 2 were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and nitrogen gas (N 2 ) sorption analysis (Brunaeur-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) calculation) techniques. The TiO 2 prepared by MAS 150 degree Celsius (4 hours) has emerged with the highest photo catalytic activity. Within 4 hours, the TiO 2 managed to catalyze the degradation of Reactive Golden Yellow R dye up to 98.51 %. This is because of the TiO 2 possessed high crystallinity of anatase phase, small crystallite size and high pore volume compared to other prepared TiO 2 . (author)

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

    KAUST Repository

    Zhang, Z.

    2012-02-10

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

  15. Engineering of highly ordered TiO2 nanopore arrays by anodization

    Science.gov (United States)

    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.

  16. XRD analysis of undoped and Fe doped TiO2 nanoparticles by Williamson Hall method

    International Nuclear Information System (INIS)

    Bharti, Bandna; Barman, P. B.; Kumar, Rajesh

    2015-01-01

    Undoped and Fe doped titanium dioxide (TiO 2 ) nanoparticles were synthesized by sol-gel method at room temperature. The synthesized samples were annealed at 500°C. For structural analysis, the prepared samples were characterized by X-ray diffraction (XRD). The crystallite size of TiO 2 and Fe doped TiO 2 nanoparticles were calculated by Scherer’s formula, and was found to be 15 nm and 11 nm, respectively. Reduction in crystallite size of TiO 2 with Fe doping was observed. The anatase phase of Fe-doped TiO 2 nanoparticles was also confirmed by X-ray diffraction. By using Williamson-Hall method, lattice strain and crystallite size were also calculated. Williamson–Hall plot indicates the presence of compressive strain for TiO 2 and tensile strain for Fe-TiO 2 nanoparticles annealed at 500°C

  17. Effect of surface ethoxy groups on photoactivity of TiO2 nanocrystals

    International Nuclear Information System (INIS)

    Tian Lihong; Deng Kejian; Ye Liqun; Zan Lin

    2011-01-01

    TiO 2 nanocrystals modified by ethoxy groups were prepared by a facile nonhydrolytic solvothermal method and characterized by XRD, TEM, TG-DTA and XPS, which showed an enhanced visible-light photocatalytic activity on the degradation of Rhodamine B compared with TiO 2 modified by benzyloxy groups and the 'naked' TiO 2 . The adsorption and degradation pathway of Rhodamine B on TiO 2 modified by ethoxy groups were also investigated. The zeta-potential (ζ) results showed that the TiO 2 modified by ethoxy groups had high negative surface charge, which incited the positive -N(Et) 2 group of RhB absorbing on the TiO 2 surface and preferably led the N-dealkylation pathway under visible light irradiation.

  18. An innovative approach to synthesize highly-ordered TiO2 nanotubes.

    Science.gov (United States)

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

    2011-02-01

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

  19. Graphene-enhanced Raman imaging of TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Naumenko, Denys; Snitka, Valentinas; Snopok, Boris; Arpiainen, Sanna; Lipsanen, Harri

    2012-01-01

    The interaction of anatase titanium dioxide (TiO 2 ) nanoparticles with chemical vapour deposited graphene sheets transferred on glass substrates is investigated by using atomic force microscopy, Raman spectroscopy and imaging. Significant electronic interactions between the nanoparticles of TiO 2 and graphene were found. The changes in the graphene Raman peak positions and intensity ratios indicate that charge transfer between graphene and TiO 2 nanoparticles occurred, increasing the Raman signal of the TiO 2 nanoparticles up to five times. The normalized Raman intensity of TiO 2 nanoparticles per their volume increased with the disorder of the graphene structure. The complementary reason for the observed enhancement is that due to the higher density of states in the defect sites of graphene, a higher electron transfer occurs from the graphene to the anatase TiO 2 nanoparticles. (paper)

  20. Enhanced photoelectrochemical and photocatalytic activity of WO3-surface modified TiO2 thin film

    Science.gov (United States)

    Qamar, Mohammad; Drmosh, Qasem; Ahmed, Muhammad I.; Qamaruddin, Muhammad; Yamani, Zain H.

    2015-02-01

    Development of nanostructured photocatalysts for harnessing solar energy in energy-efficient and environmentally benign way remains an important area of research. Pure and WO3-surface modified thin films of TiO2 were prepared by magnetron sputtering on indium tin oxide glass, and photoelectrochemical and photocatalytic activities of these films were studied. TiO2 particles were <50 nm, while deposited WO3 particles were <20 nm in size. An enhancement in the photocurrent was observed when the TiO2 surface was modified WO3 nanoparticles. Effect of potential, WO3 amount, and radiations of different wavelengths on the photoelectrochemical activity of TiO2 electrodes was investigated. Photocatalytic activity of TiO2 and WO3-modified TiO2 for the decolorization of methyl orange was tested.

  1. Electrochemical Behavior of TiO2 Nanoparticle Doped WO3 Thin Films

    Directory of Open Access Journals (Sweden)

    Suvarna R. Bathe

    2014-01-01

    Full Text Available Nanoparticle TiO2 doped WO3 thin films by pulsed spray pyrolysis technique have been studied on fluorine tin doped (FTO and glass substrate. XRD shows amorphous nature for undoped and anatase phase of TiO2 having (101 plane for nanoparticle TiO2 doped WO3 thin film. SEM shows microfibrous reticulated porous network for WO3 with 600 nm fiber diameter and nanocrystalline having size 40 nm for TiO2 nanoparticle doped WO3 thin film. TiO2 nanoparticle doped WO3 thin film shows ~95% reversibility due to may be attributed to nanocrystalline nature of the film, which helpful for charge insertion and deinsertion process. The diffusion coefficient for TiO2 nanoparticle doped WO3 film is less than undoped WO3.

  2. Ammonia Sensing Behaviors of TiO2-PANI/PA6 Composite Nanofibers

    Directory of Open Access Journals (Sweden)

    Fenglin Huang

    2012-12-01

    Full Text Available Titanium dioxide-polyaniline/polyamide 6 (TiO2-PANI/PA6 composite nanofibers were prepared by in situ polymerization of aniline in the presence of PA6 nanofibers and a sputtering-deposition process with a high purity titanium sputtering target. TiO2-PANI/PA6 composite nanofibers and PANI/PA6 composite nanofibers were fabricated for ammonia gas sensing. The ammonia sensing behaviors of the sensors were examined at room temperature. All the results indicated that the ammonia sensing property of TiO2-PANI/PA6 composite nanofibers was superior to that of PANI/PA6 composite nanofibers. TiO2-PANI/PA6 composite nanofibers had good selectivity to ammonia. It was also found that the content of TiO2 had a great influence on both the morphology and the sensing property of TiO2-PANI/PA6 composite nanofibers.

  3. Eco-friendly synthesis of TiO2, Au and Pt doped TiO2 nanoparticles for dye sensitized solar cell applications and evaluation of toxicity

    Science.gov (United States)

    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.

  4. TiO2 nanofiber solid-state dye sensitized solar cells with thin TiO2 hole blocking layer prepared by atomic layer deposition

    International Nuclear Information System (INIS)

    Li, Jinwei; Chen, Xi; Xu, Weihe; Nam, Chang-Yong; Shi, Yong

    2013-01-01

    We incorporated a thin but structurally dense TiO 2 layer prepared by atomic layer deposition (ALD) as an efficient hole blocking layer in the TiO 2 nanofiber based solid-state dye sensitized solar cell (ss-DSSC). The nanofiber ss-DSSCs having ALD TiO 2 layers displayed increased open circuit voltage, short circuit current density, and power conversion efficiency compared to control devices with blocking layers prepared by spin-coating liquid TiO 2 precursor. We attribute the improved photovoltaic device performance to the structural integrity of ALD-coated TiO 2 layer and consequently enhanced hole blocking effect that results in reduced dark leakage current and increased charge carrier lifetime. - Highlights: • TiO 2 blocking locking layer prepared by atomic layer deposition (ALD) method. • ALD-coated TiO 2 layer enhanced hole blocking effect. • ALD blocking layer improved the voltage, current and efficiency. • ALD blocking layer reduced dark leakage current and increased electron lifetime

  5. Engineering the TiO2 -graphene interface to enhance photocatalytic H2 production.

    Science.gov (United States)

    Liu, Lichen; Liu, Zhe; Liu, Annai; Gu, Xianrui; Ge, Chengyan; Gao, Fei; Dong, Lin

    2014-02-01

    In this work, TiO2 -graphene nanocomposites are synthesized with tunable TiO2 crystal facets ({100}, {101}, and {001} facets) through an anion-assisted method. These three TiO2 -graphene nanocomposites have similar particle sizes and surface areas; the only difference between them is the crystal facet exposed in TiO2 nanocrystals. UV/Vis spectra show that band structures of TiO2 nanocrystals and TiO2 -graphene nanocomposites are dependent on the crystal facets. Time-resolved photoluminescence spectra suggest that the charge-transfer rate between {100} facets and graphene is approximately 1.4 times of that between {001} facets and graphene. Photoelectrochemical measurements also confirm that the charge-separation efficiency between TiO2 and graphene is greatly dependent on the crystal facets. X-ray photoelectron spectroscopy reveals that Ti-C bonds are formed between {100} facets and graphene, while {101} facets and {001} facets are connected with graphene mainly through Ti-O-C bonds. With Ti-C bonds between TiO2 and graphene, TiO2 -100-G shows the fastest charge-transfer rate, leading to higher activity in photocatalytic H2 production from methanol solution. TiO2 -101-G with more reductive electrons and medium interfacial charge-transfer rate also shows good H2 evolution rate. As a result of its disadvantageous electronic structure and interfacial connections, TiO2 -001-G shows the lowest H2 evolution rate. These results suggest that engineering the structures of the TiO2 -graphene interface can be an effective strategy to achieve excellent photocatalytic performances. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Synthesis of Various Metal/TiO2 Core/shell Nanorod Arrays

    Science.gov (United States)

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

    2011-02-01

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

  7. Characterization of manufactured TiO2 nanoparticles

    Science.gov (United States)

    Motzkus, C.; Macé, T.; Vaslin-Reimann, S.; Ausset, P.; Maillé, M.

    2013-04-01

    Technological advances in nanomaterials have allowed the development of new applications in industry, increasing the probability of finding airborne manufactured and engineered nano-objects in the workplace, as well as in ambient air. Scientific studies on health and environmental risks have indicated that airborne nano-objects in ambient air have potential adverse effects on the health of exposed workers and the general population. For regulatory purposes, ambient measurements of particulate matter are based on the determination of mass concentrations for PM10 and PM2.5, as regulated in the European Directive 2008/50/EC. However, this legislation is not suitable for airborne manufactured and engineered nano-objects. Parameters characterising ultrafine particles, such as particle number concentration and size distribution, are under consideration for future health-based legislation, to monitor workplaces and to control industrial processes. Currently, there are no existing regulations covering manufactured airborne nano-objects. There is therefore a clear, unaddressed need to focus on the toxicology and exposure assessment of nano-objects such as titanium dioxide (TiO2), which are manufactured and engineered in large quantities in industry. To perform reliable toxicology studies it is necessary to determine the relevant characteristics of nano-objects, such as morphology, surface area, agglomeration, chemical composition, particle size and concentration, by applying traceable methods. Manufacturing of nanomaterials, and their use in industrial applications, also require traceable characterisation of the nanomaterials, particularly for quality control of the process. The present study arises from the OECD WPMN sponsorship programme, supported by the French Agency for Environmental and Occupational Health Safety (ANSES), in order to develop analytical methods for the characterization of TiO2 nanoparticles in size and count size distribution, based on different techniques to characterize five different manufactured TiO2 nanoparticles. In this study, different measurement techniques have been implemented: Transmission Electron Microscopy (TEM), Scanning Mobility Particle Sizer (SMPS) and Aerodynamic Particle Sizer (APS). The TEM results lead to a relatively good agreement between data from the manufacturer and our characterizations of primary particle size. With regard to the dustiness, the results show a strong presence of agglomerates / aggregates of primary particles and a significant presence of emitted airborne nanoparticles with a diameter below 100 nm (composed of isolated primary particles and small aggregates / agglomerates formed from a few primary particles): the number proportion of these particles varies from 0 to 44 % in the measurement range 14-360 nm depending on the types of powders and corrections of measurements.

  8. Characterization of manufactured TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Motzkus, C; Macé, T; Vaslin-Reimann, S; Ausset, P; Maillé, M

    2013-01-01

    Technological advances in nanomaterials have allowed the development of new applications in industry, increasing the probability of finding airborne manufactured and engineered nano-objects in the workplace, as well as in ambient air. Scientific studies on health and environmental risks have indicated that airborne nano-objects in ambient air have potential adverse effects on the health of exposed workers and the general population. For regulatory purposes, ambient measurements of particulate matter are based on the determination of mass concentrations for PM10 and PM2.5, as regulated in the European Directive 2008/50/EC. However, this legislation is not suitable for airborne manufactured and engineered nano-objects. Parameters characterising ultrafine particles, such as particle number concentration and size distribution, are under consideration for future health-based legislation, to monitor workplaces and to control industrial processes. Currently, there are no existing regulations covering manufactured airborne nano-objects. There is therefore a clear, unaddressed need to focus on the toxicology and exposure assessment of nano-objects such as titanium dioxide (TiO 2 ), which are manufactured and engineered in large quantities in industry. To perform reliable toxicology studies it is necessary to determine the relevant characteristics of nano-objects, such as morphology, surface area, agglomeration, chemical composition, particle size and concentration, by applying traceable methods. Manufacturing of nanomaterials, and their use in industrial applications, also require traceable characterisation of the nanomaterials, particularly for quality control of the process. The present study arises from the OECD WPMN sponsorship programme, supported by the French Agency for Environmental and Occupational Health Safety (ANSES), in order to develop analytical methods for the characterization of TiO 2 nanoparticles in size and count size distribution, based on different techniques to characterize five different manufactured TiO 2 nanoparticles. In this study, different measurement techniques have been implemented: Transmission Electron Microscopy (TEM), Scanning Mobility Particle Sizer (SMPS) and Aerodynamic Particle Sizer (APS). The TEM results lead to a relatively good agreement between data from the manufacturer and our characterizations of primary particle size. With regard to the dustiness, the results show a strong presence of agglomerates / aggregates of primary particles and a significant presence of emitted airborne nanoparticles with a diameter below 100 nm (composed of isolated primary particles and small aggregates / agglomerates formed from a few primary particles): the number proportion of these particles varies from 0 to 44 % in the measurement range 14-360 nm depending on the types of powders and corrections of measurements.

  9. Positron annihilation lifetime characterization of oxygen ion irradiated rutile TiO2

    Science.gov (United States)

    Luitel, Homnath; Sarkar, A.; Chakrabarti, Mahuya; Chattopadhyay, S.; Asokan, K.; Sanyal, D.

    2016-07-01

    Ferromagnetic ordering at room temperature has been induced in rutile phase of TiO2 polycrystalline sample by O ion irradiation. 96 MeV O ion induced defects in rutile TiO2 sample has been characterized by positron annihilation spectroscopic techniques. Positron annihilation results indicate the formation of cation vacancy (VTi, Ti vacancy) in these irradiated TiO2 samples. Ab initio density functional theoretical calculations indicate that in TiO2 magnetic moment can be induced either by creating Ti or O vacancies.

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

    Science.gov (United States)

    Yoon, Yeoungchin; Park, Jeongwon

    2018-04-01

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

  11. Annealing of TiO2 Films Deposited on Si by Irradiating Nitrogen Ion Beams

    International Nuclear Information System (INIS)

    Yokota, Katsuhiro; Yano, Yoshinori; Miyashita, Fumiyoshi

    2006-01-01

    Thin TiO2 films were deposited on Si at a temperature of 600 deg. C by an ion beam assisted deposition (IBAD) method. The TiO2 films were annealed for 30 min in Ar at temperatures below 700 deg. C. The as-deposited TiO2 films had high permittivities such 200 εo and consisted of crystallites that were not preferentially oriented to the c-axis but had an expanded c-axis. On the annealed TiO2 films, permittivities became lower with increasing annealing temperature, and crystallites were oriented preferentially to the (110) plane

  12. Synthesis of Nd3+doped TiO2 nanoparticles and Its Optical Behaviour

    Directory of Open Access Journals (Sweden)

    Ezhil Arasi S.

    2017-04-01

    Full Text Available Pure and Rare earth ion doped TiO2 nanoparticles were synthesized by Sol-gel method. The synthesized TiO2 nanoparticles were characterized by X-ray diffraction, Raman spectroscopy, UV–Vis spectroscopy and photoluminescence emission spectra. From the UV-visible measurement, the absorption edge of Nd3+-TiO2 was shifted to a higher wavelength side with decreasing band gap. Photoluminescence emission studies reveal the energy transfer mechanism of Nd3+ doped TiO2 nanoparticles explain.

  13. Defective TiO2 with oxygen vacancies: synthesis, properties and photocatalytic applications

    Science.gov (United States)

    Pan, Xiaoyang; Yang, Min-Quan; Fu, Xianzhi; Zhang, Nan; Xu, Yi-Jun

    2013-04-01

    Titanium dioxide (TiO2), as an important semiconductor metal oxide, has been widely investigated in the field of photocatalysis. The properties of TiO2, including its light absorption, charge transport and surface adsorption, are closely related to its defect disorder, which in turn plays a significant role in the photocatalytic performance of TiO2. Among all the defects identified in TiO2, oxygen vacancy is one of the most important and is supposed to be the prevalent defect in many metal oxides, which has been widely investigated both by theoretical calculations and experimental characterizations. Here, we give a short review on the existing strategies for the synthesis of defective TiO2 with oxygen vacancies, and the defect related properties of TiO2 including structural, electronic, optical, dissociative adsorption and reductive properties, which are intimately related to the photocatalytic performance of TiO2. In particular, photocatalytic applications with regard to defective TiO2 are outlined. In addition, we offer some perspectives on the challenge and new direction for future research in this field. We hope that this tutorial minireview would provide some useful contribution to the future design and fabrication of defective semiconductor-based nanomaterials for diverse photocatalytic applications.Titanium dioxide (TiO2), as an important semiconductor metal oxide, has been widely investigated in the field of photocatalysis. The properties of TiO2, including its light absorption, charge transport and surface adsorption, are closely related to its defect disorder, which in turn plays a significant role in the photocatalytic performance of TiO2. Among all the defects identified in TiO2, oxygen vacancy is one of the most important and is supposed to be the prevalent defect in many metal oxides, which has been widely investigated both by theoretical calculations and experimental characterizations. Here, we give a short review on the existing strategies for the synthesis of defective TiO2 with oxygen vacancies, and the defect related properties of TiO2 including structural, electronic, optical, dissociative adsorption and reductive properties, which are intimately related to the photocatalytic performance of TiO2. In particular, photocatalytic applications with regard to defective TiO2 are outlined. In addition, we offer some perspectives on the challenge and new direction for future research in this field. We hope that this tutorial minireview would provide some useful contribution to the future design and fabrication of defective semiconductor-based nanomaterials for diverse photocatalytic applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00476g

  14. Enhancing lipid productivity of Chlorella vulgaris using oxidative stress by TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Kang, Nam Kyu; Lee, Bongsoo; Choi, Gang-Guk; Moon, Myounghoon; Park, Min S.; Yang, Ji-Won; Lim, JitKang

    2014-01-01

    Ability to increase the lipid production in microalgae is one of the heavily sought-after ideas to improve the economic feasibility of microalgae-derived transportation fuels for commercial applications. We used the oxidative stress by TiO 2 nanoparticles, a well-known photocatalyst, to induce lipid production in microalgae. Chlorella vulgaris UTEX 265 was cultivated under various concentrations of TiO 2 ranging from 0.1 to 5 g/L under UV-A illumination. Maximum specific growth rate was affected in responding to TiO 2 concentrations. In the presence of UV-A, chlorophyll concentration was decreased at the highest concentration of TiO 2 (5 g/L TiO 2 ) by oxidative stress. The fatty acid methyl ester (FAME) composition analysis suggested that oxidative stress causes the accumulation and decomposition of lipids. The highest FAME productivity was 18.2 g/L/d under low concentrations of TiO 2 (0.1 g/L) and a short induction time (two days). The controlled condition of TiO 2 /UV-A inducing oxidative stress (0.1 g/L TiO 2 and two days induction) could be used to increase the lipid productivity of C. vulgaris UTEX 265. Our results show the possibility of modulating the lipid induction process through oxidative stress with TiO 2 /UV-A

  15. Preparation and characterization of nanocrystalline porous TiO2/WO3 composite thin films

    International Nuclear Information System (INIS)

    Hsu, C.-S.; Lin, C.-K.; Chan, C.-C.; Chang, C.-C.; Tsay, C.-Y.

    2006-01-01

    TiO 2 materials possessing not only photocatalytic but also electrochromic properties have attracted many research and development interests. Though WO 3 exhibits excellent electrochromic properties, the much higher cost and water-sensitivity of WO 3 as compared with the TiO 2 may restrict the practical application of WO 3 materials. In the present study, the feasibility of preparing nanocrystalline porous TiO 2 /WO 3 composite thin films was investigated. Precursors of sols TiO 2 and/or WO 3 and polystyrene microspheres were used to prepare nanocrystalline pure TiO 2 , WO 3 , and composite TiO 2 /WO 3 thin films by spin coating. The spin-coated thin films were amorphous and, after heat treating at a temperature of 500 o C, nanocrystalline TiO 2 , TiO 2 /WO 3 , and WO 3 thin films with or without pores were prepared successfully. The heat-treated thin films were colorless and coloration-bleaching phenomena can be observed during cyclic voltammetry tests. The heat-treated thin films exhibited good reversible electrochromic behavior while the porous TiO 2 /WO 3 composite film exhibited improved electrochromic properties

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

    Science.gov (United States)

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

    2017-08-01

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

  17. One-component solution system to prepare nanometric anatase TiO2

    International Nuclear Information System (INIS)

    Trung, Tran; Ha, Chang-Sik

    2004-01-01

    A novel one-pot synthesis route was proposed to prepare nanometric anatase TiO 2 using trichloroethylene as reaction medium, which may have great advantage over multicomponent solution systems when TiO 2 is used as a reinforcing filler for polymers dissolved in trichloroethylene. The anatase TiO 2 nanoparticles were characterized using X-ray diffraction (XRD), scanning electron microscopy and small-angle X-ray scattering (SAXS). It was found that the diameters of TiO 2 nanoparticles are in the range from 5 to 13 nm

  18. Photodecomposition of volatile organic compounds using TiO2 nanoparticles.

    Science.gov (United States)

    Jwo, Ching-Song; Chang, Ho; Kao, Mu-Jnug; Lin, Chi-Hsiang

    2007-06-01

    This study examined the photodecomposition of volatile organic compounds (VOCs) using TiO2 catalyst fabricated by the Submerged Arc Nanoparticle Synthesis System (SANSS). TiO2 catalyst was employed to decompose volatile organic compounds and compare with Degussa-P25 TiO2 in terms of decomposition efficiency. In the electric discharge manufacturing process, a Ti bar, applied as the electrode, was melted and vaporized under high temperature. The vaporized Ti powders were then rapidly quenched under low-temperature and low-pressure conditions in deionized water, thus nucleating and forming nanocrystalline powders uniformly dispersed in the base solvent. The average diameter of the TiO2 nanoparticles was 20 nm. X-ray diffraction analysis confirmed that the nanoparticles in the deionized water were Anatase type TiO2. It was found that gaseous toluene exposed to UV irradiation produced intermediates that were even harder to decompose. After 60-min photocomposition, Degussa-P25 TiO2 reduced the concentration of gaseous toluene to 8.18% while the concentration after decomposition by SANSS TiO2 catalyst dropped to 0.35%. Under UV irradiation at 253.7 +/- 184.9 nm, TiO2 prepared by SANSS can produce strong chemical debonding energy, thus showing great efficiency, superior to that of Degussa-P25 TiO2, in decomposing gaseous toluene and its intermediates.

  19. Enhanced bonding between TiO2-Graphene oxide

    DEFF Research Database (Denmark)

    Naknikham, Usuma; Buffa, Vittorio; Yue, Yuanzheng

    analysis. Besides, the study of Ti-O-C and Ti-C interface bonding was carried out using XPS. The band-gap energy was determined using a UV-VIS spectrophotometer equipped with an integrating sphere. Thus, it was possible for us to determine the reactivity of the new photocatalysts under the visible light...... as photocatalysts, which can efficiently react with organic species under solar light and can enhance the adsorption of water pollutants [3]. Many studies have shown that TiO2-GO heterostructures can quickly mineralize organic dyes in solution under UV-light. However, it is not clear if these materials can provide...... the same performances under sunlight and with complex real water systems. Hence, this research aims to study the photocatalystic property on GO-TiO2 composites with aqueous solutions of selected emerging pollutants under visible light. The samples were synthesized via the in-situ sol-gel nucleation...

  20. Branched nanotrees with immobilized acetylcholine esterase for nanobiosensor applications

    DEFF Research Database (Denmark)

    Risveden, Klas; Dick, Kimberly A; Bhand, Sunil

    2010-01-01

    A novel lab-on-a-chip nanotree enzyme reactor is demonstrated for the detection of acetylcholine. The reactors are intended for use in the RISFET (regional ion sensitive field effect transistor) nanosensor, and are constructed from gold-tipped branched nanorod structures grown on SiN(x)-covered w......A novel lab-on-a-chip nanotree enzyme reactor is demonstrated for the detection of acetylcholine. The reactors are intended for use in the RISFET (regional ion sensitive field effect transistor) nanosensor, and are constructed from gold-tipped branched nanorod structures grown on Si......N(x)-covered wafers. Two different reactors are shown: one with simple, one-dimensional nanorods and one with branched nanorod structures (nanotrees). Significantly higher enzymatic activity is found for the nanotree reactors than for the nanorod reactors, most likely due to the increased gold surface area...

  1. Fabrication, characterization and photocatalytic properties of Ag nanoparticles modified TiO2 NTs

    International Nuclear Information System (INIS)

    Wang Qingyao; Yang Xiuchun; Liu Dan; Zhao Jianfu

    2012-01-01

    Graphical abstract: The TiO 2 NTs were first treated with bi-functional mercaptoacetic acid linkers (HOOC–R–S). The –OH group on the surface of TiO 2 NT provides a strong affinity with the carboxylate group in the linker molecules. The thiol functional group in the linker molecules facilitates the binding with Ag from AgNO 3 solution. After Ag + ions were reduced by NaBH 4 , Ag nanoparticles formed by nucleation and growth. Highlights: ► Ag nanoparticles with an average diameter of 9.2 nm were filled in the TiO 2 nanotubes by a successive ionic layer adsorption and reaction (SILAR) technique. ► Bi-functional mercaptoacetic acid linkers were used to bind TiO 2 nanotubes with Ag nanoparticles. ► Ag nanoparticles modification of TiO 2 NTs largely enhanced the photocatalytic degradation of methyl orange under ultraviolet light irradiation. - Abstract: Ordered anatase TiO 2 nanotubes (TiO 2 NTs) on Ti substrate were synthesized by electrochemical anodization and subsequently vapor-thermal treatment. Ag nanoparticles were decorated on TiO 2 NTs by successive ionic layer adsorption and reaction (SILAR) technique. Raman spectroscopy, X-ray absorption near edge spectroscopy (XANES), X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for the characterization of surface morphology, phase composition, and microstructure of the original TiO 2 NTs, the vapor-thermally treated TiO 2 NTs and the Ag nanoparticles decorated TiO 2 NTs. The results indicate that vapor-thermal treatment favors to the transformation of amorphous TiO 2 into anatase phase. Increasing the SILAR cycle times favors to increase the loaded amounts of Ag nanoparticles in TiO 2 NTs. Ag nanoparticles are uniformly distributed in the TiO 2 NTs, and the SILAR process does not damage the ordered tubular structure. A possible formation mechanism of Ag/TiO 2 NTs has also been proposed. The photocatalytic results showed that the Ag nanoparticle modified TiO 2 NTs largely enhanced the photocatalytic degradation of methyl orange under ultraviolet light irradiation.

  2. The Effects of Anchor Groups on (1) TiO2-Catalyzed Photooxidation and (2) Linker-Assisted Assembly on TiO2

    Science.gov (United States)

    Anderson, Ian Mark

    Quantum dot-sensitized solar cells (QDSSCs) are a popular target for research due to their potential for highly efficient, easily tuned absorption. Typically, light is absorbed by quantum dots attached to a semiconductor substrate, such as TiO2, via bifunctional linker molecules. This research aims to create a patterned monolayer of linker molecules on a TiO2 film, which would in turn allow the attachment of a patterned layer of quantum dots. One method for the creation of a patterned monolayer is the functionalization of a TiO2 film with a linker molecule, followed by illumination with a laser at 355 nm. This initiates a TiO 2-catalyzed oxidation reaction, causing loss of surface coverage. A second linker molecule can then be adsorbed onto the TiO2 surface in the illuminated area. Towards that end, the behaviors of carboxylic and phosphonic acids adsorbed on TiO2 have been studied. TiO2 films were functionalized by immersion in solutions a single adsorbate and surface coverage was determined by IR spectroscopy. It is shown that phosphonic acids attain higher surface coverage than carboxylic acids, and will displace them from TiO2 when in a polar solvent. Alkyl chain lengths, which can influence stabilities of monolayers, are shown not to have an effect on this relationship. Equilibrium binding data for the adsorption of n-hexadecanoic acid to TiO2 from a THF solution are presented. It is shown that solvent polarity can affect monolayer stability; carboxylates and phosphonates undergo more desorption into polar solvents than nonpolar. Through illumination, it was possible to remove nearly all adsorbed linkers from TiO2. However, the illuminated areas were found not to be receptive to attachment by a second adsorbate. A possible reason for this behavior is presented. I also report on the synthesis and characterization of a straight-chain, thiol-terminated phosphonic acid. Initial experiments involving monolayer formation and quantum dot attachment are presented. Finally, it was found that quantum dots attach in high amounts to linker-functionalized TiO2 when suspended in pyridine. This increased surface attachment was present even when the linker molecule used lacked a functional group which would bind to the CdSe surface.

  3. The synthesis of aqueous-dispersible anatase TiO2 nanoplatelets

    International Nuclear Information System (INIS)

    Shan Guobin; Demopoulos, George P

    2010-01-01

    Aqueous well-dispersed and phase-pure anatase TiO 2 truncated octahedron nanoplatelets (NPLs) were prepared via controlled hydrolysis of titanium tetrachloride (TiCl 4 ) in ethylene glycol at 240 deg. C. Two shapes, square and hexagon, were observed by microscopy, exactly corresponding to the truncated octahedron NPLs. Ethylene glycol was found to produce water in situ that reacts with TiCl 4 to produce TiO 2 and HCl-the latter promoting TiO 2 colloid peptization. TiO 2 truncated octahedron NPLs are formed under the stabilizing action of ethylene glycol thermolysis derivatives, such as aldehydes. Crystal growth of the TiO 2 NPLs was affected by the reaction temperature that determines the water production rate and HCl-assisted peptization. TGA and FT-IR results showed ∼1.2% ethylene glycol thermolysis derivatives are attached to the surface of the TiO 2 NPLs, which prevents their agglomeration, hence making them easily dispersible in aqueous media. HR-TEM and SAED results showed that the TiO 2 NPLs are well crystallized and that the SAED patterns of the single TiO 2 NPL changes with its size and shape. XRD patterns showed that the TiO 2 NPLs are phase-pure anatase and the percentage of the {101} plane in the TiO 2 NPLs to be only 18%-a structural feature that renders the TiO 2 NPLs with enhanced UV absorption and reactivity properties.

  4. The Influence of Cr3+ on TiO2 Crystal Growth and Photoactivity Properties

    Science.gov (United States)

    Wahyuningsih, S.; Hidayatika, W. N.; Sari, P. L.; Sari, P. P.; Hidayat, R.; Munawaroh, H.; Ramelan, A. H.

    2018-03-01

    The photocatalyst technology is an integrated combination of photochemical processes and catalysis in order to carry out a chemical transformation reaction. One of the semiconductor materials that have good photocatalytic activity is TiO2 anatase. This study aim to determine the effect of the Cr3+ addition on the growth of TiO2 rutile crystal and the increasing of TiO2 photoactivity. Diffractogram X-Ray of the samples showed that the synthesized TiO2 at 400 °C has been produced 100% TiO2 anatase. Synthesis of TiO2 doped Cr3+ composite was using wet impregnation method. The TiO2 doped Cr3+ composites have beed grown by annealed at a temperature of 300, 400, 500, 600 and 700 °C, respectively Annealing process have capabled to gain to the TiO2 doped Cr3+ nanocomposite. The result product annealed at 500 °C only appear anatase phase due to the Cr3+ addition influence that was able to suppress the growth of rutile. Identification of TiO2 doped Cr3+ composite using Fourier Transform Infra-Red (FT-IR) showed O-Cr vibration at 2283.72 cm-1. The TiO2 doped Cr3+ photoactivity was studied to degrade Rhodamin B. The best result on photodegradation of Rhodamin B was performed by using TiO2 doped Cr3+ composite which was annealed at 700 °C i.e. 74.71%.

  5. Rapid detection of TiO2 (E171) in table sugar using Raman spectroscopy.

    Science.gov (United States)

    Tan, Chen; Zhao, Bin; Zhang, Zhiyun; He, Lili

    2017-02-01

    The potential toxic effects of titanium dioxide (TiO 2 ) to humans remain debatable despite its broad application as a food additive. Thus, confirmation of the existence of TiO 2 particles in food matrices and subsequently quantifying them are becoming increasingly critical. This study developed a facile, rapid (E171) from food products (e.g., table sugar) by Raman spectroscopy. To detect TiO 2 particles from sugar solution, sequential centrifugation and washing procedures were effectively applied to separate and recover 97% of TiO 2 particles from the sugar solution. The peak intensity of TiO 2 sensitively responded to the concentration of TiO 2 with a limit of detection (LOD) of 0.073 mg kg -1 . In the case of sugar granules, a mapping technique was applied to directly estimate the level of TiO 2 , which can be potentially used for rapid online monitoring. The plot of averaged intensity to TiO 2 concentration in the sugar granules exhibited a good linear relationship in the wide range of 5-2000 mg kg -1 , with an LOD of 8.46 mg kg -1 . Additionally, we applied Raman spectroscopy to prove the presence of TiO 2 in sugar-coated doughnuts. This study begins to fill in the analytical gaps that exist regarding the rapid detection and quantification of TiO 2 in food, which facilitate the risk assessment of TiO 2 through food exposure.

  6. Enhanced photoelectrocatalytic performance for degradation of diclofenac and mechanism with TiO2 nano-particles decorated TiO2 nano-tubes arrays photoelectrode

    International Nuclear Information System (INIS)

    Cheng, Xiuwen; Liu, Huiling; Chen, Qinghua; Li, Junjing; Wang, Pu

    2013-01-01

    In this study, TiO 2 nano-particles decorated TiO 2 nano-tubes arrays (TiO 2 NPs/TiO 2 NTAs) photoelectrodes have been successfully prepared through anodization, combined with ultrasonic strategy, followed by annealing post-treatment. The morphology and structure of the as-prepared TiO 2 NPs/TiO 2 NTAs photoelectrodes were characterized by scanning electrons microscopy (SEM), N 2 adsorption/desorption isotherms, X-ray diffraction (XRD) and UV–visible light diffuse reflection spectroscopy (DRS). In addition, the generation of hydroxyl radicals (·OH) was detected by a photoluminescence (PL) spectra using terephthalic acid (TA) as a probe molecule. Furthermore, the photoelectrochemical (PECH) properties of TiO 2 NPs/TiO 2 NTAs photoanode were investigated through transient open circuit potential (OCP), photocurrent response (PCR) and electrochemical impedance spectroscopy (EIS). It was found that TiO 2 NPs/TiO 2 NTAs photoelectrode exhibited a distinct decrease of OCP of −0.219 mV cm −2 and PCR of 0.049 mA cm −2 , while a significantly enhanced photoelectrocatalytic (PEC) efficiency of 63.6% (0.4 V vs. SCE) for the degradation of diclofenac. Moreover, the enhanced PEC mechanism of TiO 2 NPs/TiO 2 NTAs photoanode was proposed. The high PEC performance could be attributed to the decoration of TiO 2 NPs, which could improve the mobility and separation efficiency of photoinduced charge carriers under external potential

  7. Photocatalytic degradation of paracetamol on TiO2 nanoparticles and TiO2/cellulosic fiber under UV and sunlight irradiation

    Directory of Open Access Journals (Sweden)

    Nabil Jallouli

    2017-05-01

    Full Text Available In the present study, photocatalytic degradation of acetaminophen ((N-(4-hydroxyphe-nylacetamide, an analgesic drug has been investigated in a batch reactor using TiO2 P25 as a photocatalyst in slurry and under UV light. Using TiO2 P25 nanoparticles, much faster photodegradation of paracetamol and effective mineralization occurred, more than 90% of 2.65 × 10−4 M paracetamol was degraded under UV irradiation. Changes in pH values affected the adsorption and the photodegradation of paracetamol. pH 9.0 is found to be the optimum for the photodegradation of paracetamol. HPLC detected hydroquinone, benzoquinone, p-nitrophenol, and 1,2,4-trihydroxybenzene during the TiO2-assisted photodegradation of paracetamol among which some pathway products are disclosed for the first time. The results showed that TiO2 suspension/UV system is more efficient than the TiO2/cellulosic fiber mode combined to solar light for the photocatalytic degradation of paracetamol. Nerveless the immobilization of TiO2 showed many advantages over slurry system because it can enhance adsorption properties while allowing easy separation of the photocatalyst from the treated solution with improved reusable performance.

  8. SiO2@TiO2 Coating: Synthesis, Physical Characterization and Photocatalytic Evaluation

    Directory of Open Access Journals (Sweden)

    A. Rosales

    2018-03-01

    Full Text Available Use of silicon dioxide (SiO2 and titanium dioxide (TiO2 have been widely investigated individually in coatings technology, but their combined properties promote compatibility for different innovative applications. For example, the photocatalytic properties of TiO2 coatings, when exposed to UV light, have interesting environmental applications, such as air purification, self-cleaning and antibacterial properties. However, as reported in different pilot projects, serious durability problems, associated with the adhesion between the substrate and TiO2, have been evidenced. Thus, the aim of this work is to synthesize SiO2 together with TiO2 to increase the durability of the photocatalytic coating without affecting its photocatalytic potential. Therefore, synthesis using sonochemistry, synthesis without sonochemistry, physical characterization, photocatalytic evaluation, and durability of the SiO2, SiO2@TiO2 and TiO2 coatings are presented. Results indicate that using SiO2 improved the durability of the TiO2 coating without affecting its photocatalytic properties. Thus, this novel SiO2@TiO2 coating shows potential for developing long-lasting, self-cleaning and air-purifying construction materials.

  9. Synthesis of TiO2-doped SiO2 composite films and its applications

    Indian Academy of Sciences (India)

    Wintec

    structure of the titanium oxide species in the TiO2-doped SiO2 composite films and the photocatalytic reactiv- ity in order to ... gaku D-max γA diffractometer with graphite mono- chromized ... FT–IR absorption spectra of TiO2-doped SiO2 com-.

  10. TiO2-Based Advanced Oxidation Nanotechnologies For Water Purification And Reuse

    Science.gov (United States)

    TiO2 photocatalysis, one of the UV-based advanced oxidation technologies (AOTs) and nanotechnologies (AONs), has attracted great attention for the development of efficient water treatment and purification systems due to the effectiveness of TiO2 to generate ...

  11. Oxidation and photo-oxidation of water on TiO2 surface

    DEFF Research Database (Denmark)

    Valdes, A.; Qu, Z.W.; Kroes, G.J.

    2008-01-01

    The oxidation and photo-oxidation of water on the rutile TiO2(110) surface is investigated using density functional theory (DFT) calculations. We investigate the relative stability of different surface terminations of TiO2 interacting with H2O and analyze the overpotential needed for the electrol...

  12. Hazards of TiO2 and amorphous SiO2 nanoparticles

    NARCIS (Netherlands)

    Reijnders, L.; Kahn, H.A.; Arif, I.A.

    2012-01-01

    TiO2 and amorphous SiO2 nanoparticles have been described as ‘safe’, ‘non-toxic’ and ‘environment friendly’ in scientific literature. However, though toxicity data are far from complete, there is evidence that these nanoparticles are hazardous. TiO2 nanoparticles have been found hazardous to humans

  13. Spectral Sensitization of TiO2 Substrates by Monolayers of Porphyrin Heterodimers

    NARCIS (Netherlands)

    Koehorst, R.B.M.; Boschloo, G.K.; Savenije, T.J.; Goossens, A.; Schaafsma, T.J.

    2000-01-01

    Photoelectrochemical cells have been constructed by depositing monolayers of oriented covalently linked zinc/free base porphyrin heterodimers onto ~30 nm nonporous layers of TiO2 on ITO, deposited by metal-organic chemical vapor deposition (MO-CVD), and onto ~100 nm porous, nanostructured TiO2

  14. Construction of hydrophobic wood surfaces by room temperature deposition of rutile (TiO2) nanostructures

    Science.gov (United States)

    Rongbo Zheng; Mandla A. Tshabalala; Qingyu Li; Hongyan Wang

    2015-01-01

    A convenient room temperature approach was developed for growing rutile TiO2 hierarchical structures on the wood surface by direct hydrolysis and crystallization of TiCl3 in saturated NaCl aqueous solution.The morphology and the crystal structure of TiO2 coated on the wood surface were characterized...

  15. TiO2 Based Photocatalyst: From Synthesis and Characterization to Optimization and Design

    DEFF Research Database (Denmark)

    Su, Ren

    2012-01-01

    TiO2 based photocatalyst has attracted gerat attentions from both fundamental and an applied aspects in water/air purifications and energy production. In this thesis, series of well-defined TiO2 photocatalyst with various parameters (i.e., polymorph composition, shape, impurity concentration, sur...

  16. Characterization of low temperature deposited atomic layer deposition TiO2 for MEMS applications

    NARCIS (Netherlands)

    Huang, Y.; Pandraud, G.; Sarro, P.M.

    2012-01-01

    TiO2 is an interesting and promising material for micro-/nanoelectromechanical systems (MEMS/NEMS). For high performance and reliable MEMS/NEMS, optimization of the optical characteristics, mechanical stress, and especially surface smoothness of TiO2 is required. To overcome the roughness issue of

  17. The Effects of Leaching Process to the TiO2 Synthesis from Bangka Ilmenite

    Science.gov (United States)

    Wahyuningsih, S.; Ramelan, A. H.; Pramono, E.; Argawan, P.; Djatisulistya, A.; Firdiyono, F.; Sulistiyono, E.; Sari, P. P.

    2018-03-01

    Ilmenite mineral is a naturally occurring iron titanate (FeTiO3) and is abundant in nature. The separation of components into TiO2 and Fe2O3 must be expand. The purpose of this research is to synthesis TiO2 nanoparticles from the filtrate of Bangka ilmenite leaching process. Leaching of ilmenite was done with H2SO4 and HCl at various concentrations. The formation of TiO2 crystal determined by hydrolysis conditions and condensation reaction. TiO2 synthesized from the filtrate of sulfuric acid leaching that produced from TiO2 anatase phase when hydrolyzed in an aquaregia solvent and low concentrations of HCl (0.1M). Hydrolysis conditions at higher concentrations of HCl (1M) was produced TiO2 anatase-rutile phase. The synthesis of TiO2 from the filtrate of hydrochloric acid leaching was produced anatase phase. While the condition under the alcoholic solvent (2-propanol: H2O (v/v) = 9: 1) anatase phase crystallites grow in the temperature range up to 550 °C, above this temperature, TiO2 transform into rutile phase.

  18. Hydrothermal synthesis of TiO2 Nanotubes: Microwave heating versus conventional heating

    CSIR Research Space (South Africa)

    Sikhwivhilu, LM

    2010-01-01

    Full Text Available The influence of the method of synthesis in the properties of the tubular structures derived from TiO2 was investigated using XRD, SEM and BET analysis. The use of microwave irradiation resulted in the formation of TiO2 tubes comprising anatase...

  19. TiO2 Photocatalysis Damages Lipids and Proteins in Escherichia coli

    NARCIS (Netherlands)

    Carre, Gaelle; Hamon, Erwann; Ennahar, Said; Estner, Maxime; Lett, Marie-Claire; Horvatovich, Peter; Gies, Jean-Pierre; Keller, Valerie; Keller, Nicolas; Andre, Philippe

    This study investigates the mechanisms of UV-A (315 to 400 nm) photocatalysis with titanium dioxide (TiO2) applied to the degradation of Escherichia coli and their effects on two key cellular components: lipids and proteins. The impact of TiO2 photocatalysis on E. coli survival was monitored by

  20. New TiO2/DSAT Immobilization System for Photodegradation of Anionic and Cationic Dyes

    Directory of Open Access Journals (Sweden)

    Wan Izhan Nawawi Wan Ismail

    2015-01-01

    Full Text Available A new immobilized TiO2 technique was prepared by coating TiO2 solution onto double-sided adhesive tape (DSAT as a thin layer binder without adding any organic additives. Glass plate was used as support material to immobilized TiO2/DSAT. Two different charges of dyes were applied, namely, anionic reactive red 4 (RR4 and cationic methylene blue (MB dyes. Photocatalytic degradation of RR4 and MB dyes was observed under immobilized TiO2/DSAT with the degradation rate slightly lower and higher, respectively, compared with TiO2 in suspension mode. It was observed that DSAT is able to provide a very strong intact between glass and TiO2 layers thus making the reusability of immobilized TiO2/DSAT be up to 30 cycles. In fact, a better photodegradation activity was observed by number of cycles due to increasing formation of pores on TiO2 surface observed by SEM analysis.

  1. Photocatalytic properties of porous TiO2/Ag thin films

    International Nuclear Information System (INIS)

    Chang, C.-C.; Chen, J.-Y.; Hsu, T.-L.; Lin, C.-K.; Chan, C.-C.

    2008-01-01

    In this study, nanocrystalline TiO 2 /Ag composite thin films were prepared by a sol-gel spin-coating technique. By introducing polystyrene (PS) spheres into the precursor solution, porous TiO 2 /Ag thin films were prepared after calcination at a temperature of 500 deg. C for 4 h. Three different sizes (50, 200, and 400 nm) of PS spheres were used to prepare porous TiO 2 films. The as-prepared TiO 2 and TiO 2 /Ag thin films were characterized by X-ray diffractometry (XRD) and by scanning electron microscopy to reveal structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methylene blue under UV irradiation. When PS spheres of different sizes were introduced after calcination, the as-prepared TiO 2 films exhibited different porous structures. XRD results showed that all TiO 2 /Ag films exhibited a major anatase phase. The photodegradation of porous TiO 2 thin films prepared with 200 nm PS spheres and doped with 1 mol% Ag exhibited the best photocatalytic efficiency where ∼ 100% methylene blue was decomposed within 8 h under UV exposure

  2. Synthesis of nanocrystalline TiO2 thin films by liquid phase ...

    Indian Academy of Sciences (India)

    WINTEC

    goes degradation efficiently in presence of TiO2 thin films by exposing its aqueous solution to .... Figure 6. Photodegradation of IGOR organic dye by a. bare TiO2 thin film and b. ... Meng L-J and Dos Santos M P 1993 Thin Solid Films 226 22.

  3. Synthesis, structure and photocatalytic activity of nano TiO2 and ...

    Indian Academy of Sciences (India)

    salicylic acid over combustion-synthesized nano TiO2 under UV and solar exposure has been carried out. Under identical conditions of UV exposure, the initial degra- dation rate of phenol with combustion-synthesized TiO2 is two times higher than the initial degradation rate of phenol with Degussa P25, the commercial ...

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

    Science.gov (United States)

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

    2012-04-01

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

  5. Growth and characterization of hydroxyapatite nanorice on TiO2 nanofibers

    KAUST Repository

    Chetibi, Loubna; Hamana, Djamel; Achour, Slimane

    2014-01-01

    with anatase TiO2 nanofibers. These nanofibers were prepared by in situ oxidation of Ti foils in a concentrated solution of H 2O2 and NaOH, followed by proton exchange and calcinations. Afterward, TiO2 nanofibers on Ti substrate were coated with HA

  6. Electrospinning processed nanofibrous TiO2 membranes for photovoltaic applications

    Science.gov (United States)

    Onozuka, Katsuhiro; Ding, Bin; Tsuge, Yosuke; Naka, Takayuki; Yamazaki, Michiyo; Sugi, Shinichiro; Ohno, Shingo; Yoshikawa, Masato; Shiratori, Seimei

    2006-02-01

    We have recently fabricated dye-sensitized solar cells (DSSCs) comprising nanofibrous TiO2 membranes as electrode materials. A thin TiO2 film was pre-deposited on fluorine doped tin oxide (FTO) coated conducting glass substrate by immersion in TiF4 aqueous solution to reduce the electron back-transfer from FTO to the electrolyte. The composite polyvinyl acetate (PVac)/titania nanofibrous membranes can be deposited on the pre-deposited thin TiO2 film coated FTO by electrospinning of a mixture of PVac and titanium isopropoxide in N,N-dimethylformamide (DMF). The nanofibrous TiO2 membranes were obtained by calcining the electrospun composite nanofibres of PVac/titania as the precursor. Spectral sensitization of the nanofibrous TiO2 membranes was carried out with a ruthenium (II) complex, cis-dithiocyanate-N,N'-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid) ruthenium (II) dihydrate. The results indicated that the photocurrent and conversion efficiency of electrodes can be increased with the addition of the pre-deposited TiO2 film and the adhesion treatment using DMF. Additionally, the dye loading, photocurrent, and efficiency of the electrodes were gradually increased by increasing the average thickness of the nanofibrous TiO2 membranes. The efficiency of the fibrous TiO2 photoelectrode with the average membrane thickness of 3.9 µm has a maximum value of 4.14%.

  7. Nanoscale surface potential imaging of the photocatalytic TiO2 films on aluminum

    DEFF Research Database (Denmark)

    Daviðsdóttir, Svava; Dirscherl, Kai; Canulescu, Stela

    2013-01-01

    in the surface potential of TiO2 coatings upon UV-illumination are closely correlated to the band gap and thickness of the coatings. The inhomogeneity surface potential distribution of a 100 nm TiO2 film indicates a heterogeneous coating. Transition to a homogeneous surface potential distribution was observed...

  8. TiO2@C Core-Shell Nanoparticles Formed by Polymeric Nano-Encapsulation

    Directory of Open Access Journals (Sweden)

    Mitra eVasei

    2014-07-01

    Full Text Available TiO2 semiconducting nanoparticles are known to be photocatalysts of moderate activity due to their high band-gap and high rate of electron-hole recombination. The formation of a shell of carbon around the core of TiO2, i.e. the formation of TiO2@C nanoparticles, is believed to partly alleviate these problems. It is usually achieved by a hydrothermal treatment in a presence of a sugar derivative. We present here a novel method for the formation of highly uniform C shell around TiO2 nanoparticles. For this purpose, TiO2 nanoparticles were dispersed in water using an oligomeric dispersant prepared by Reversible Addition-Fragmentation chain Transfer (RAFT polymerization. Then the nanoparticles were engaged into an emulsion polymerization of acrylonitrile, resulting in the formation of a shell of polyacrylonitrile (PAN around each TiO2 nanoparticles. Upon pyrolisis, the PAN was transformed into carbon, resulting in the formation of TiO2@C nanoparticles. The structure of the resulting particles was elucidated by X-Ray diffraction, FTIR, UV-VIS and Raman spectroscopy as well as TEM microscopy. Preliminary results about the use of the TiO2@C particles as photocatalysts for the splitting of water are presented. They indicate that the presence of the C shell is responsible for a significant enhancement of the photocurrent.

  9. Hot corrosion performance of LVOF sprayed Al2O3–40% TiO2 ...

    Indian Academy of Sciences (India)

    ficients of thermal expansions of the two. ... size 40 mesh just prior to deposition of the coating. Al2O3–. 40% TiO2 ... the laboratory Kanthal wire tube furnace, which was cali- ... formation of TiO2, Al2O3 and Al2Ti7O15 phases in the coat- ing.

  10. Intrinsic Photocatalytic Assessment of Reactively Sputtered TiO2 Films

    NARCIS (Netherlands)

    Rafieian Boroujeni, Damon; Driessen, Rick Theodorus; Driessen, Rick T.; Ogieglo, Wojciech; Lammertink, Rob G.H.

    2015-01-01

    Thin TiO2 films were prepared by DC magnetron reactive sputtering at different oxygen partial pressures. Depending on the oxygen partial pressure during sputtering, a transition from metallic Ti to TiO2 was identified by spectroscopic ellipsometry. The crystalline nature of the film developed during

  11. Electrochemical characteristics of porous TiO2 encapsulated silicon anode

    International Nuclear Information System (INIS)

    Jeon, Bup Ju; Lee, Joong Kee

    2011-01-01

    Graphical abstract: Cycling performances of the TiO 2 coated silicon anode at different catalyst pH values. Display Omitted Highlights: → TiO 2 coated silicon was used as the anode material for lithium batteries. → TiO 2 layer acted as a buffer layer for reducing the volume expansion. → Pore size distribution of TiO 2 coated silicon influenced discharge capacity. → Higher capacity retention was exhibited at pH 10.7. - Abstract: TiO 2 coated silicon, which was prepared by the modified sol-gel method, was employed as the anode material for lithium secondary batteries and the relationship between the diffusivity and electrochemical characteristics was investigated. The results showed that the physical properties of the samples, such as their diffusivity and pore size distribution, enhanced the cycling efficiency of the TiO 2 coated silicon, probably due to the reduction of the side reactions, which may be closely related to the pore size distribution of the TiO 2 coating layer. The pore size of the coating layer plays an important role in retarding the lithium ion diffusion. In the experimental range studied herein, higher capacity retention was exhibited for the TiO 2 coated silicon prepared at pH 10.7.

  12. Fullerene C70 decorated TiO2 nanowires for visible-light-responsive photocatalyst

    International Nuclear Information System (INIS)

    Cho, Er-Chieh; Ciou, Jing-Hao; Zheng, Jia-Huei; Pan, Job; Hsiao, Yu-Sheng; Lee, Kuen-Chan; Huang, Jen-Hsien

    2015-01-01

    Graphical abstract: - Highlights: • TiO 2 nanowire decorated with C 60 and C 70 derivatives has been synthesized. • The fullerenes impede the charge recombination due to its high electron affinity. • The fullerenes expand the utilization of solar light from UV to visible light. • The modified-TiO 2 has great biocompatibility. - Abstract: In this study, we have synthesized C 60 and C 70 -modified TiO 2 nanowire (NW) through interfacial chemical bonding. The results indicate that the fullerenes (C 60 and C 70 derivatives) can act as sinks for photogenerated electrons in TiO 2 , while the fullerene/TiO 2 is illuminated under ultraviolet (UV) light. Therefore, in comparison to the pure TiO 2 NWs, the modified TiO 2 NWs display a higher photocatalytic activity under UV irradiation. Moreover, the fullerenes also can function as a sensitizer to TiO 2 which expand the utilization of solar light from UV to visible light. The results reveal that the C 70 /TiO 2 NWs show a significant photocatalytic activity for degradation of methylene blue (MB) in visible light region. To better understand the mechanism responsible for the effect of fullerenes on the photocatalytic properties of TiO 2 , the electron only devices and photoelectrochemical cells based on fullerenes/TiO 2 are also fabricated and evaluated.

  13. Complex impedance study on nano-CeO2 coating TiO2

    International Nuclear Information System (INIS)

    Zhang Mei; Wang Honglian; Wang Xidong; Li Wenchao

    2006-01-01

    Titanium dioxide (TiO 2 ) nanoparticles and cerium dioxide (CeO 2 ) nanoparticles coated titanium dioxide (TiO 2 ) nanoparticles (CeO 2 -TiO 2 nanoparticles) have been successfully synthesized by sol-gel method. The complex impedance of the materials was investigated. The grain resistance, boundary resistance and activation energy of the nanoparticles were calculated according to Arrhenius equation. According to calculating results, the active capacity of pure TiO 2 nanoparticles has been improved because of nano-CeO 2 coating. An optimal CeO 2 content of 4.9 mol% was achieved. The high resolution electron microscopy images of CeO 2 -TiO 2 nanoparticles showed that TiO 2 nanoparticles, as a core, were covered by CeO 2 nanoparticles. The average size of CeO 2 coating TiO 2 nanoparticles was about 70 nm. Scanning electron microscopy observation indicted that CeO 2 nanoparticle coating improved the separation, insulation, and stability the CeO 2 -TiO 2 nanoparticles, which was benefit to the activity of materials

  14. MoSe2 modified TiO2 nanotube arrays with superior photoelectrochemical performance

    Science.gov (United States)

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

    2018-04-01

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

  15. Azo dyes decomposition on new nitrogen-modified anatase TiO2 with high adsorptivity

    International Nuclear Information System (INIS)

    Janus, M.; Choina, J.; Morawski, A.W.

    2009-01-01

    New vis active photocatalyst was obtained by the modification of commercial anatase TiO 2 (Police, Poland) in pressure reactor in an ammonia water atmosphere at 100 o C for 4 h. The photocatalytic activity of new material was tested during three azo dyes decomposition: monoazo (Reactive Read), diazo (Reactive Black) and poliazodye (Direct Green). Obtained photocatalyst had new bands at 1430-1440 cm -1 attributed to the bending vibrations of NH 4 + and at 1535 cm -1 associated with NH 2 groups or NO 2 and NO. UV-vis/DR spectra of photocatalyst had also insignificant decrease in visible region. Fluorescence technique was used for studying the amount of hydroxyl radicals produced on TiO 2 surface during visible light irradiation. The hydroxyl radicals produced react with coumarin present in the solution to form 7-hydroxycoumarin which has fluorescent capacity. Photocatalytic activity of modified TiO 2 was compared with commercial titanium dioxide P25 (Degussa, Germany). The photocatalytic activity of TiO 2 /N was higher than that of unmodified material and P25 under visible light irradiation. The ability for dye adsorption (Reactive Red) on photocatalyst surface was also tested. Unmodified TiO 2 and P25 has isotherm of adsorption by Freundlich model, and nitrogen-modified TiO 2 by Langmuir model. The presence of nitrogen at the surface of TiO 2 significantly increased adsorption capacity of TiO 2 as well as OH· radicals formation under visible radiation.

  16. Interfacial enhancement of carbon fiber composites by growing TiO2 nanowires onto amine-based functionalized carbon fiber surface in supercritical water

    Science.gov (United States)

    Ma, Lichun; Li, Nan; Wu, Guangshun; Song, Guojun; Li, Xiaoru; Han, Ping; Wang, Gang; Huang, Yudong

    2018-03-01

    A novel amine-based functionalization method was developed to improve the interfacial adhesion between TiO2 NWs and CFs in supercritical water. The microstructure, morphology and mechanical properties of CFs were investigated. It was found that introducing hexamethylenetetramine (HMTA) dendrimers and branched polyethyleneimine (PEI) on CF could increase significantly the adhesion strength between CF and TiO2 NWs and their interfacial shear strength with epoxy resin, and the order is CF-PEI-TiO2 NWs > CF-HMTA-TiO2 NWs > CF-COOH-TiO2 NWs > CF-TiO2 NW. Meanwhile, the reinforcing mechanisms and interfacial failure modes have also been discussed. We believe that these effective methods may provide theoretical foundation for the preparation of high performance composite materials.

  17. Effects of various physicochemical characteristics on the toxicities of ZnO and TiO2 nanoparticles toward human lung epithelial cells

    International Nuclear Information System (INIS)

    Hsiao, I-Lun; Huang, Yuh-Jeen

    2011-01-01

    Although novel nanomaterials are being produced and applied in our daily lives at a rapid pace, related health and environmental toxicity assessments are lagging behind. Recent reports have concluded that the physicochemical properties of nanoparticles (NPs) have a crucial influence on their toxicities and should be evaluated during risk assessments. Nevertheless, several controversies exist regarding the biological effects of NP size and surface area. In addition, relatively few reports describe the extents to which the physicochemical properties of NPs influence their toxicity. In this study, we used six self-synthesized and two commercial ZnO and TiO 2 nanomaterials to evaluate the effects of the major physicochemical properties of NPs (size, shape, surface area, phase, and composition) on human lung epithelium cells (A549). We characterized these NPs using transmission electron microscopy, X-ray diffraction, the Brunauer-Emmett-Teller method, and dynamic laser scattering. From methyl thiazolyl tetrazolium (MTT) and Interleukin 8 (IL-8) assays of both rod- and sphere-like ZnO NPs, we found that smaller NPs had greater toxicity than larger ones-a finding that differs from those of previous studies. Furthermore, at a fixed NP size and surface area, we found that the nanorod ZnO particles were more toxic than the corresponding spherical ones, suggesting that both the size and shape of ZnO NPs influence their cytotoxicity. In terms of the effect of the surface area, we found that the contact area between a single NP and a single cell was more important than the total specific surface area of the NP. All of the TiO 2 NP samples exhibited cytotoxicities lower than those of the ZnO NP samples; among the TiO 2 NPs, the cytotoxicity increased in the following order: amorphous > anatase > anatase/rutile; thus, the phase of the NPs can also play an important role under size-, surface area-, and shape-controlled conditions. - Research Highlights: → Evaluate the

  18. First-Principles Modeling of Polaron Formation in TiO2 Polymorphs.

    Science.gov (United States)

    Elmaslmane, A R; Watkins, M B; McKenna, K P

    2018-06-21

    We present a computationally efficient and predictive methodology for modeling the formation and properties of electron and hole polarons in solids. Through a nonempirical and self-consistent optimization of the fraction of Hartree-Fock exchange (α) in a hybrid functional, we ensure the generalized Koopmans' condition is satisfied and self-interaction error is minimized. The approach is applied to model polaron formation in known stable and metastable phases of TiO 2 including anatase, rutile, brookite, TiO 2 (H), TiO 2 (R), and TiO 2 (B). Electron polarons are predicted to form in rutile, TiO 2 (H), and TiO 2 (R) (with trapping energies ranging from -0.02 eV to -0.35 eV). In rutile the electron localizes on a single Ti ion, whereas in TiO 2 (H) and TiO 2 (R) the electron is distributed across two neighboring Ti sites. Hole polarons are predicted to form in anatase, brookite, TiO 2 (H), TiO 2 (R), and TiO 2 (B) (with trapping energies ranging from -0.16 eV to -0.52 eV). In anatase, brookite, and TiO 2 (B) holes localize on a single O ion, whereas in TiO 2 (H) and TiO 2 (R) holes can also be distributed across two O sites. We find that the optimized α has a degree of transferability across the phases, with α = 0.115 describing all phases well. We also note the approach yields accurate band gaps, with anatase, rutile, and brookite within six percent of experimental values. We conclude our study with a comparison of the alignment of polaron charge transition levels across the different phases. Since the approach we describe is only two to three times more expensive than a standard density functional theory calculation, it is ideally suited to model charge trapping at complex defects (such as surfaces and interfaces) in a range of materials relevant for technological applications but previously inaccessible to predictive modeling.

  19. Positively charged TiO2 particles in non-polar system for electrophoretic display

    International Nuclear Information System (INIS)

    Chang, Young Seon

    2005-02-01

    Electrophoretic display uses a technique called electrophoresis to represent images and letters electronically with electronic ink. Although it has good characteristics such as wide viewing angle, high contrast ratio and extremely low power consumption, there are still several issues to be resolved to improve its performances. Higher mobility and stability of the ink particles are the most important issues among them. In this study, TiO 2 particles coated with acrylamide were found to be effective ink particles that satisfy higher mobility and stability. The TiO 2 particles coated with 5∼40% acrylamide were prepared by dispersion polymerization using monomers of methyl methacrylate (MMA) and acrylamide. The TiO 2 particles coated with acrylamide were dispersed in isopar-G with sorbitan esters such as span 20, span 80 and span 85. The size of the TiO 2 particles were changed from 200±150 nm to 350∼500 nm by the coating process. The morphology of coated particles was observed using a transmission electron microscope (TEM) and thermogravimetric analysis (TGA). From the TGA results, the weight fraction of TiO 2 and polymer in coated particle were calculated. From the zeta potential measurement, it was shown that as acrylamide concentration was increased from 5% to 30%, zeta potential of the coated TiO 2 particles was increased from 50mV to about 230mV. The zeta potential of the coated TiO 2 particles with 40% acrylamide was decreased to 50mV. As a stabilizer, span 85 was the most effective surfactant to improve stability of the TiO 2 particles coated with acrylamide among used surfactants in this study. Span 85 showed best stability in the storage test with TiO 2 particles coated with 10% acrylamide. The mobility of TiO 2 particles coated with acrylamide with span 85 in dye solution (Oil Blue-N dissolved in isopar-G) were measured by ITO cell test. The mobility of TiO 2 particles coated with 10∼30% acrylamide was over 600μm 2 /Vs while the mobility of TiO 2 particles coated with 40% acrylamide was about 400μm 2 /Vs. Span 85 was effective to improve the mobility of TiO 2 particles coated with acrylamide. As the concentration of span 85 was increased from 0 to 1.75 vol %, mobility of the TiO 2 particles coated with 20% acrylamide was increased from 250μm 2 /Vs to about 720μ 2 /Vs

  20. Structural, optical and ferromagnetic properties of Cr doped TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Choudhury, Biswajit; Choudhury, Amarjyoti

    2013-01-01

    Graphical abstract: Doping of Cr 3+ distorts the lattice of TiO 2 , generate oxygen vacancies and create d-band states in the mid band gap of TiO 2 . Incorporation of Cr 3+ also imparts magnetism in non-magnetic TiO 2 by undergoing coupling with the neighboring oxygen vacancies. -- Highlights: • Incorporation of Cr 3+ increases the concentration of oxygen vacancies in TiO 2 nanoparticles. • Doped TiO 2 nanoparticles contain absorption peaks corresponding to d–d transition of Cr 3+ into TiO 2 . • Pure and doped TiO 2 nanoparticles contain emission peaks related to oxygen vacancies. • Pure TiO 2 shows diamagnetism while Cr doped TiO 2 shows ferromagnetism. • The ferromagnetism is due to the interaction of Cr 3+ ions via oxygen vacancies. -- Abstract: Cr doped TiO 2 nanoparticles are prepared with three different concentrations of chromium, 1.5%, 3.0% and 4.5 mol% respectively. Doping decreases the crystallinity and increases the width of the X-ray diffraction peak. The Raman active E g peak of TiO 2 nanoparticles become asymmetric and shifted to higher energy on doping of 4.5% chromium. Electron paramagnetic resonance spectra reveal the presence of Cr 3+ in the host TiO 2 matrix. The absorption spectra of Cr doped TiO 2 nanoparticles contain absorption peaks corresponding to d–d transition of Cr 3+ in octahedral coordination. Most of the visible emission peaks are due to the electrons trapped in the oxygen vacancy centers. Undoped TiO 2 nanoparticles show diamagnetism at room temperature while all chromium doped samples show ferromagnetism. The magnetization of the doped samples increases at 1.5% and 3.0% and decreases at 4.5%. The ferromagnetism arises owing to the interaction of the neighboring Cr 3+ ions via oxygen vacancies. The decrease of magnetization at the highest doping is possibly due to the antiferromagnetic interactions of Cr 3+ pairs or due to Cr 3+ -O 2− -Cr 3+ superexchange interaction in the lattice

  1. Synergistic effects for the TiO2/RuO2/Pt photodissociation of water

    Energy Technology Data Exchange (ETDEWEB)

    Blondel, G; Harriman, A; Williams, D

    1983-07-01

    Compressed discs of naked TiO2 or TiO2 coated with a thin film of a noble metal (e.g. Pt) do not photodissociate water upon illumination with UV light, but small amounts of H2 are generated if the TiO2 has been reduced in a stream of H2 at 600 C. Discs prepared from mixtures of TiO2/RuO2 facilitate the UV photodissociation of water into H2 and O2 although the yields are very low. When a thin (about 9 nm) film of Pt is applied to the TiO2/RuO2 discs, the yields of H2 and O2 observed upon irradiation with UV light are improved drastically. 25 references.

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

    Directory of Open Access Journals (Sweden)

    Xie Yi

    2009-01-01

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

  3. Properties of phases in HfO2-TiO2 system

    International Nuclear Information System (INIS)

    Red'ko, V.P.; Terekhovskij, P.B.; Majster, I.M.; Shevchenko, A.V.; Lopato, L.M.; Dvernyakova, A.A.

    1990-01-01

    A study was made on axial and linear coefficients of thermal expansion (CTE) of HfO 2 -TiO 2 system samples in concentration range of 25-50 mol% TiO 2 . Samples, containing 35 and 37 mol% TiO 2 , are characterized by the lowest values of linear CTE. Dispersion of the basic substances doesn't affect CTE value. Correlation with axial and linear CTE of samples in ZrO 2 -TiO 2 system was conducted. Presence of anisotropy of change of lattice parameters was supported for samples, containing 37.5 and 40 mol% TiO 2 . Polymorphous transformations for hafnium titanate were not revealed

  4. Preparation and performance of photocatalytic TiO2 immobilized on palladium-doped carbon fibers

    International Nuclear Information System (INIS)

    Zhu Yaofeng; Fu Yaqin; Ni Qingqing

    2011-01-01

    Pd-modified carbon fibers (CFs) are obtained by a facile oxidation-reduction method and then dip-coated in a sol-gel of titanium dioxide (TiO 2 ) to form supported TiO 2 /Pd-CF photocatalysts. The morphology of the Pd-modified CFs and the amount Pd deposited are characterized by field emission scanning electron microscopy and atomic absorption spectrometry, respectively. X-ray diffraction is used to investigate the crystal structures of the TiO 2 photocatalyst. Acid orange II is used as a model contaminant to evaluate the photocatalytic properties of the photocatalyst under UV irradiation. TiO 2 /Pd-CF exhibits higher catalytic activity than TiO 2 /CF towards the degradation of acid orange II. Optimum photocatalytic performance and support properties are achieved when the Pd particle loading is about 10.8 mg/g.

  5. Effects of highly ordered TiO2 nanotube substrates on the nucleation of Cu electrodeposits.

    Science.gov (United States)

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

    2010-05-01

    We investigated the effects of TiO2 nanotube substrates on the nucleation density of Cu during electrodeposition in a solution of CuSO4 and H2SO4 at 50 degrees C compared with those of pure Ti and micro-porous TiO2 substrates. During electrodeposition, the density of Cu nuclei on the TiO2 nanotube substrate increased and the average size of Cu nuclei decreased with increasing anodizing voltage and time for the synthesis of the substrate. In addition, the nucleation density of Cu electrodeposits on the highly ordered TiO2 nanotube substrate was much higher than that on pure Ti and micro-porous TiO2 substrates.

  6. Preparation of anatase TiO2 thin films by vacuum arc plasma evaporation

    International Nuclear Information System (INIS)

    Miyata, Toshihiro; Tsukada, Satoshi; Minami, Tadatsugu

    2006-01-01

    Anatase titanium dioxide (TiO 2 ) thin films with high photocatalytic activity have been prepared with deposition rates as high as 16 nm/min by a newly developed vacuum arc plasma evaporation (VAPE) method using sintered TiO 2 pellets as the source material. Highly transparent TiO 2 thin films prepared at substrate temperatures from room temperature to 400 deg. C exhibited photocatalytic activity, regardless whether oxygen (O 2 ) gas was introduced during the VAPE deposition. The highest photocatalytic activity and photo-induced hydrophilicity were obtained in anatase TiO 2 thin films prepared at 300 deg. C, which correlated to the best crystallinity of the films, as evidenced from X-ray diffraction. In addition, a transparent and conductive anatase TiO 2 thin film with a resistivity of 2.6 x 10 -1 Ω cm was prepared at a substrate temperature of 400 deg. C without the introduction of O 2 gas

  7. Three-dimensional observation of TiO2 nanostructures by electron tomography

    KAUST Repository

    Suh, Young Joon

    2013-03-01

    Three-dimensional nanostructures of TiO2 related materials including nanotubes, electron acceptor materials in hybrid polymer solar cells, and working electrodes of dye sensitized solar cells (DSSCs) were visualized by electron tomography as well as TEM micrographs. The regions on the wall of TiO2 nanotubes where the streptavidins were attached were elucidated by electron tomogram analysis. The coverage of TiO2 nanotubes by streptavidin was also investigated. The TiO2 nanostructures in hybrid polymer solar cells made by sol-gel and atomic layer deposition (ALD) methods and the morphologies of pores between TiO2 particles in DSSCs were also observed by reconstructed three-dimensional images made by electron tomography. © 2012 Elsevier Ltd.

  8. Antimicrobial and Barrier Properties of Bovine Gelatin Films Reinforced by Nano TiO2

    Directory of Open Access Journals (Sweden)

    R. Nassiri

    2013-11-01

    Full Text Available The effects of nano titanium dioxide incorporation were investigated on the water vaporpermeability, oxygen permeability, and antimicrobial properties of bovine gelatin films. The nano TiO2 (TiO2-N was homogenized by sonication and incorporated into bovine gelatin solutions at different concentrations(e.g. 1, 2, 3, and 5% w/w of dried gelatin. The permeability of the films to water vapor and oxygen wassignificantly decreased by incorporating of low concentration TiO2-N to gelatin solutions. TiO2-N gelatin filmsshowed an excellent antimicrobial activity against Staphylococcus aureus and Escherichia coli. Theseproperties suggest that TiO2-N has the potential as filler in gelatin-based films for using as an active packagingmaterials in pharmaceutical and food packaging industries.

  9. Optimized monolayer grafting of 3-aminopropyltriethoxysilane onto amorphous, anatase and rutile TiO 2

    Science.gov (United States)

    Song, Yan-Yan; Hildebrand, Helga; Schmuki, Patrik

    2010-02-01

    Experimental conditions were studied for optimized attachment of 3-aminopropyltriethoxysilane (APTES) onto amorphous, anatase and rutile titanium dioxide (TiO 2) surfaces. The attachment process and extent was characterized using X-ray photoelectron spectroscopy (XPS). In particular, the effect of attachment time, silane concentration, reaction temperature and the TiO 2 crystalline structure on the growth kinetics of the silane layers was studied. The measurements reveal that typically monolayers are more dense on amorphous than on crystalline TiO 2. The results show that critical experimental conditions exist where APTES attachment to the TiO 2 surface changes from a monolayer to a multilayer growth mode. The obtained results and parameters to produce optimized APTES layers are of a high practical relevance as APTES attachment often constitutes the initial step for organic modification of TiO 2 surface with biorelevant molecules such as proteins, enzymes or growth factors.

  10. One-Dimensional TiO2 Nanostructures as Photoanodes for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Jie Qu

    2013-01-01

    Full Text Available Titanium dioxide (TiO2 is star materials due to its remarkable optical and electronic properties, resulting in various applications, especially in the fields of dye-sensitized solar cells (DSSCs. Photoanode is the most important part of the DSSCs, which help to adsorb dye molecules and transport the injected electrons. The size, structure, and morphology of TiO2 photoanode have been found to show significant influence on the photovoltaic performance of DSSCs. In this paper, we briefly summarize the synthesis and properties of one-dimensional (1D TiO2 nanomaterials (bare 1D TiO2 nanomaterial and 1D hierarchical TiO2 and their photovoltaic performance in DSSCs.

  11. Excess electrons in reduced rutile and anatase TiO2

    Science.gov (United States)

    Yin, Wen-Jin; Wen, Bo; Zhou, Chuanyao; Selloni, Annabella; Liu, Li-Min

    2018-05-01

    As a prototypical photocatalyst, TiO2 is a material of scientific and technological interest. In photocatalysis and other applications, TiO2 is often reduced, behaving as an n-type semiconductor with unique physico-chemical properties. In this review, we summarize recent advances in the understanding of the fundamental properties and applications of excess electrons in reduced, undoped TiO2. We discuss the characteristics of excess electrons in the bulk and at the surface of rutile and anatase TiO2 focusing on their localization, spatial distribution, energy levels, and dynamical properties. We examine specific features of the electronic states for photoexcited TiO2, for intrinsic oxygen vacancy and Ti interstitial defects, and for surface hydroxyls. We discuss similarities and differences in the behaviors of excess electrons in the rutile and anatase phases. Finally, we consider the effect of excess electrons on the reactivity, focusing on the interaction between excess electrons and adsorbates.

  12. ADSORCIÓN DE ALDEHÍDOS INSATURADOS SOBRE TiO2

    Directory of Open Access Journals (Sweden)

    Natalia Ortega

    2012-01-01

    Full Text Available En el presente trabajo se estudió la adsorción de aldehídos insaturados sobre la superficie del TiO2. Para evaluar su eficiencia como catalizador, se realizaron experimentos de fotocatálisis heterogénea de p-nitrofenol (PNF y una muestra proveniente de efluentes industriales. Se empleó un simulador solar y cuatro sistemas de TiO2: el TiO2-sólo (sin modificar y los sistemas TiO2-dienal constituidos por la adsorción química de 2,4 hexadienal, 2,4 heptadienal y el trans-cinamaldehído sobre la superficie del TiO2. La adsorción de los aldehídos insaturados sobre el TiO2 se cuantificó empleando los modelos de adsorción de Langmuir y Freundlich. Se evaluó la influencia del pH en los sistemas TiO2-dienal y su efecto en la degradación fotocatalítica del PNF. En condiciones básicas, la constante de velocidad del PNF es mayor al emplear los sistemas TiO2-dienal en comparación con el TiO2-sólo, mientras que en condiciones ácidas se encontró la tendencia opuesta. El sistema TiO2-cina resultó ser el fotocatalizador de mayor eficiencia.

  13. Synthesis and photocatalytic activity of graphene based doped TiO2 nanocomposites

    International Nuclear Information System (INIS)

    Gu, Yongji; Xing, Mingyang; Zhang, Jinlong

    2014-01-01

    Graphical abstract: - Highlights: • Graphene based doped TiO 2 nanocomposites were prepared. • The intimate contact between doped TiO 2 and graphene is achieved simultaneously. • These nanocomposites showed higher photocatalytic activity than TiO 2 and doped TiO 2 . • Photocatalytic mechanism was explained thoroughly. - Abstract: The nanocomposites of reduced graphene oxide based nitrogen doped TiO 2 (N–TiO 2 –RGO) and reduced graphene oxide based nitrogen and vanadium co-doped TiO 2 (N, V–TiO 2 –RGO) were prepared via a facile hydrothermal reaction of graphene oxide and TiO 2 in a water solvent. In this hydrothermal treatment, the reduction of graphene oxide and the intimate contact between nitrogen doped TiO 2 (N–TiO 2 ) or nitrogen and vanadium co-doped TiO 2 (N,V–TiO 2 ) and the RGO sheet is achieved simultaneously. Both N–TiO 2 –RGO and N,V–TiO 2 –RGO nanocomposites exhibit much higher visible light photocatalytic activity than N–TiO 2 and N,V–TiO 2 , and the order of visible light photocatalytic activity is N,V–TiO 2 –RGO > N–TiO 2 –RGO > N,V–TiO 2 > N–TiO 2 > TiO 2 . According to the characterization, the enhanced photocatalytic activity of the nanocomposites is attributed to reasons, such as enhancement of adsorption of pollutants, light absorption intensity, minimizing the recombination of photoinduced electrons and holes and more excited states of these nanocomposites under visible light irradiation. Overall, this work provides a more marked contrast of graphene based semiconductor nanocomposites and a more comprehensive explanation of the mechanism

  14. Recovery TiO2 by leaching process of carbothermic reduced Kalimantan ilmenite

    Science.gov (United States)

    Wahyuningsih, S.; Sari, P. P.; Ramelan, A. H.

    2018-05-01

    Ilmenite naturally occurred in iron titanate (FeTiO3) minerals. The separation of natural ilmenite into TiO2 and Fe2O3 need to be explored to gain the high purity separation product. A new combination method named of carbothermic reduction, acidic-leaching and complexation by EDTA were proposed for separation TiO2 from Ilmenite. Roasting of ilmenite was carried out at 950 °C for 1 h by the addition of activated carbon with mass ratio of ilmenite : activated carbon =4:3. The carbothermic reduction was carried out to yield a high separation of initial content of ilmenite that will be easily to dissolve within hydrochloric acid solution in leaching process. The composition of ilmenite observed by X-Ray Fluoresences (XRF) changed after the carbothermic reduction process and the dominant content is TiO2 (57.56%). X-Ray Diffraction (XRD) of roasted ilmenite composed of decomposed product of ilmenite i.e. hematite (Fe2O3), TiO2 anatase, TiO2 rutile, and inorganic salt. The leaching of the roasted ilmenite has been done by sulphuric acid solution (6 M) to gain the titanyl sulphate solution. Separation of iron impurities of TiO2 gel from titanyl sulphate (TiOSO4) solution was conducted by complexation method using EDTA as a complexation agent. The characteristic of TiO2 obtained using XRD showed that TiO2 is anatase type and the percentage of TiO2 using XRF showed that TiO2 content of 86,03%.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    Highlights: • V-doped TiO 2 /diatomite composite photocatalyst was synthesized. • The physiochemical property and solar light photoactivity were characterized. • The presence and influence of V ions in TiO 2 matrix was systematically analyzed. • The photocatalysis for Rhodamine B were studied under solar light illumination. - Abstract: V-doped TiO 2 /diatomite composite photocatalysts with different vanadium concentrations were synthesized by a modified sol–gel method. The diatomite was responsible for the well dispersion of TiO 2 nanoparticles on the matrix and consequently inhibited the agglomeration. V-TiO 2 /diatomite hybrids showed red shift in TiO 2 absorption edge with enhanced absorption intensity. Most importantly, the dopant energy levels were formed in the TiO 2 bandgap due to V 4+ ions substituted to Ti 4+ sites. The 0.5% V-TiO 2 /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 TiO 2 /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 TiO 2 lattice were responsible for increased visible-light absorption and electron transfer to oxygen molecules adsorbed on the surface of TiO 2 to produce superoxide radicals ·O 2 – , while V 5+ species presented on the surface of TiO 2 particles in the form of V 2 O 5 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

  16. Efficient photodecomposition of herbicide imazapyr over mesoporous Ga2O3-TiO2 nanocomposites.

    Science.gov (United States)

    Ismail, Adel A; Abdelfattah, Ibrahim; Faisal, M; Helal, Ahmed

    2018-01-15

    The unabated release of herbicide imazapyr into the soil and groundwater led to crop destruction and several pollution-related concerns. In this contribution, heterogeneous photocatalytic technique was employed utilizing mesoporous Ga 2 O 3 -TiO 2 nanocomposites for degrading imazapyr herbicide as a model pollutant molecule. Mesoporous Ga 2 O 3 -TiO 2 nanocomposites with varied Ga 2 O 3 contents (0-5wt%) were synthesized through sol-gel process. XRD and Raman spectra exhibited extremely crystalline anatase TiO 2 phase at low Ga 2 O 3 content which gradually reduced with the increase of Ga 2 O 3 content. TEM images display uniform TiO 2 particles (10±2nm) with mesoporous structure. The mesoporous TiO 2 exhibits large surface areas of 167m 2 g -1 , diminished to 108m 2 g -1 upon 5% Ga 2 O 3 incorporation, with tunable mesopore diameter in the range of 3-9nm. The photocatalytic efficiency of synthesized Ga 2 O 3 -TiO 2 nanocomposites was assessed by degrading imazapyr herbicide and comparing with commercial photocatalyst UV-100 and mesoporous Ga 2 O 3 under UV illumination. 0.1% Ga 2 O 3 -TiO 2 nanocomposite is considered the optimum photocatalyst, which degrades 98% of imazapyr herbicide within 180min. Also, the photodegradation rate of imazapyr using 0.1% Ga 2 O 3 -TiO 2 nanocomposite is nearly 10 and 3-fold higher than that of mesoporous Ga 2 O 3 and UV-100, respectively. The high photonic efficiency and long-term stability of the mesoporous Ga 2 O 3 -TiO 2 nanocomposites are ascribed to its stronger oxidative capability in comparison with either mesoporous TiO 2 , Ga 2 O 3 or commercial UV-100. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Interspace modification of titania-nanorod arrays for efficient mesoscopic perovskite solar cells

    Science.gov (United States)

    Chen, Peng; Jin, Zhixin; Wang, Yinglin; Wang, Meiqi; Chen, Shixin; Zhang, Yang; Wang, Lingling; Zhang, Xintong; Liu, Yichun

    2017-04-01

    Morphology of electron transport layers (ETLs) has an important influence on the device architecture and electronic processes of mesostructured solar cells. In this work, we thoroughly investigated the effect of the interspace of TiO2 nanorod (NR) arrays on the photovoltaic performance of the perovskite solar cells (PSCs). Along with the interspace in TiO2-NR arrays increasing, the thickness as well as the crystal size of perovskite capping layer are reduced accordingly, and the filling of perovskite in the channel becomes incomplete. Electrochemical impedance spectroscopy measurements reveal that this variation of perovskite absorber layer, induced by interspace of TiO2 NR arrays, causes the change of charge recombination process at the TiO2/perovskite interface, suggesting that a balance between capping layer and the perovskite filling is critical to obtain high charge collection efficiency of PSCs. A power conversion efficiency of 10.3% could be achieved through careful optimization of interspace in TiO2-NR arrays. Our research will shed light on the morphology control of ETLs with 1D structure for heterojunction solar cells fabricated by solution-deposited method.

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

    KAUST Repository

    Shi, Le

    2015-05-01

    Water splitting through photoelectrochemical reaction is widely regarded as a major method to generate H2 , a promising source of renewable energy to deal with the energy crisis faced up to human being. Efficient exploitation of visible light in practice of water splitting with pure TiO2 material, one of the most popular semiconductor material used for photoelectrochemical water splitting, is still challenging. One dimensional TiO2 nanotubes is highly desired with its less recombination with the short distance for charge carrier diffusion and light-scattering properties. This work is based on TiO2 NTPC electrode by the optimized two-step anodization method from our group. A highly crystalized p-type Cu2O layer was deposited by optimized pulse potentiostatic electrochemical deposition onto TiO2 nanotubes to enhance the visible light absorption of a pure p-type TiO2 substrate and to build a p-n junction at the interface to improve the PEC performance. However, because of the real photocurrent of Cu2O is far away from its theoretical limit and also poor stability in the aqueous environment, a design of rGO medium layer was added between TiO2 nanotube and Cu2O layer to enhance the photogenerated electrons and holes separation, extend charge carrier diffusion length (in comparison with those of conventional pure TiO2 or Cu2O materials) which could significantly increase photocurrent to 0.65 mA/cm2 under visible light illumination (>420 nm) and also largely improve the stability of Cu2O layer, finally lead to an enhancement of water splitting performance.

  19. Structural and optical properties of AgCl-sensitized TiO2 (TiO2 @AgCl prepared by a reflux technique under alkaline condition

    Directory of Open Access Journals (Sweden)

    V. A. Mu’izayanti

    Full Text Available Abstract The AgCl-sensitized TiO2 (TiO2@AgCl has been prepared from the precursor of TiO2-rutile type which on its surface adsorb chloride anion (Cl- and various amounts of silver using AgNO3 as starting material: AgNO3/(AgNO3+TiO2 mass ratio of 0.00, 1.14, 3.25, 6.38 and 10.32%. Reflux under alkaline condition was the employed technique. All samples were characterized by X-ray diffraction (XRD and diffuse reflectance UV-vis spectroscopy. The sample without the addition of AgNO3 was analyzed by scanning electron microscope and surface area analyzer. The morphology of the sample showed a distribution of microspheres of approximately 0.5 to 1.0 µm and the specific surface area was 68 m2/g. XRD patterns indicated that the sample without the addition of AgNO3 contained two types of TiO2: rutile (major and anatase (minor, whereas the samples with the addition of AgNO3 consisted of one phase of AgCl and two types of TiO2: rutile and anatase. The bandgaps of the samples were in the range of 2.97 to 3.24 eV, which were very close to the bandgap of intrinsic TiO2 powder. The presence of 0.8, 2.6 and 4.4 wt% of AgCl in each sample resulted in an additional bandgap in visible light region of 1.90, 1.94 and 2.26 eV, respectively, whereas the presence of 9.4 wt% of AgCl in the sample resulted in two bandgaps in visible light region of 1.98 and 1.88 eV.

  20. Interface actions between TiO2 and porous diatomite on the structure and photocatalytic activity of TiO2-diatomite

    International Nuclear Information System (INIS)

    Xia, Yue; Li, Fangfei; Jiang, Yinshan; Xia, Maosheng; Xue, Bing; Li, Yanjuan

    2014-01-01

    TiO 2 -diatomite photocatalysts were prepared by sol–gel process with various pre-modified diatomite. In order to obtain diatomite with different surface characteristics, two modification approaches including calcination and phosphoric acid treatment on the micro-structure of diatomite are introduced. The photocatalysts were characterized by XRD, XPS, nitrogen adsorption–desorption isotherms and micromorphology analysis. The results indicate that, compared with pure TiO 2 , the anatase-to-rutile phase transition temperature of TiO 2 loaded on diatomite carrier is significantly increased to nearly 900 °C, depending on the different pretreatment method of diatomite. The photocatalytic activities of different samples were evaluated by their degradation rate of methyl orange (MO) dye under UV and visible-light irradiation. The samples prepared by phosphoric acid pretreatment method exhibit the highest photocatalytic activity. After 90 min of UV irradiation, about 90% of MO is decomposed by the best effective photocatalyst. And after 8 h visible-light irradiation, nearly 60% of MO is decomposed by the same sample. Further mechanism investigation reveals that the H 3 PO 4 pretreatment process can obviously change the surface features of diatomite carrier, cause the formation of Si–O–Ti bond, increase the binding strength between TiO 2 and diatomite, restrain crystal growth of loaded TiO 2 , and thus form thermal-stable mesoporous structure at the granular spaces. It helps to build micro-, meso- and macro-porous hierarchical porous structure in TiO 2 -diatomite, and improves the charge and mass transfer efficiency during catalyzing process, resulting in the significantly increased photocatalytic activity of TiO 2 -diatomite pretreated by phosphoric acid.

  1. Interface actions between TiO2 and porous diatomite on the structure and photocatalytic activity of TiO2-diatomite

    Science.gov (United States)

    Xia, Yue; Li, Fangfei; Jiang, Yinshan; Xia, Maosheng; Xue, Bing; Li, Yanjuan

    2014-06-01

    TiO2-diatomite photocatalysts were prepared by sol-gel process with various pre-modified diatomite. In order to obtain diatomite with different surface characteristics, two modification approaches including calcination and phosphoric acid treatment on the micro-structure of diatomite are introduced. The photocatalysts were characterized by XRD, XPS, nitrogen adsorption-desorption isotherms and micromorphology analysis. The results indicate that, compared with pure TiO2, the anatase-to-rutile phase transition temperature of TiO2 loaded on diatomite carrier is significantly increased to nearly 900 °C, depending on the different pretreatment method of diatomite. The photocatalytic activities of different samples were evaluated by their degradation rate of methyl orange (MO) dye under UV and visible-light irradiation. The samples prepared by phosphoric acid pretreatment method exhibit the highest photocatalytic activity. After 90 min of UV irradiation, about 90% of MO is decomposed by the best effective photocatalyst. And after 8 h visible-light irradiation, nearly 60% of MO is decomposed by the same sample. Further mechanism investigation reveals that the H3PO4 pretreatment process can obviously change the surface features of diatomite carrier, cause the formation of Si-O-Ti bond, increase the binding strength between TiO2 and diatomite, restrain crystal growth of loaded TiO2, and thus form thermal-stable mesoporous structure at the granular spaces. It helps to build micro-, meso- and macro-porous hierarchical porous structure in TiO2-diatomite, and improves the charge and mass transfer efficiency during catalyzing process, resulting in the significantly increased photocatalytic activity of TiO2-diatomite pretreated by phosphoric acid.

  2. Synthesis and characterization of titanium oxide/bismuth sulfide nanorods for solar cells applications

    International Nuclear Information System (INIS)

    Solis, M.; Rincon, M. E.

    2008-01-01

    In the present work is showed the synthesis and characterization of titanium oxide/bismuth sulfide nanowires hetero-junctions for solar cells applications. Conductive glass substrates (Corning 25 x 75 mm) were coated with a thin layer of sol-gel TiO2 and used as substrates for the subsequent deposition of bismuth sulfide nanorods (BN). TiO2 films (∼400 nm) were deposited with a semiautomatic immersion system with controlled immersion/withdraw velocity, using titanium isopropoxide as the titania precursor [1]. For BN synthesis and deposition, the solvo-thermal method was used, introducing air annealed TiO2-substrates in the autoclave. The typical bilayer TiO2/BN hetero-junction was 600 nm thick. The synthesized materials (powders and films) were characterized by X-Ray Diffraction, Scanning Electron Microscopy, and UV-Visible Spectroscopy. Anatase was the crystalline phase of TiO2, while bismuth sulfide nanotubes show a diffraction pattern characteristic of bismuthinite distorted by the preferential growth of some planes [2-4]. The optoelectronic characterization of TiO2/NB hetero-junctions was compared with hetero-junctions obtained by sensitizing TiO2 with chemically deposited bismuth sulfide films. Bismuth sulfide nanowires are 2µm long and 70nm wide (aspect ratio L/D = 43), while chemically deposited bismuth sulfide have L/D = 1, therefore the effect of particle size evaluation and geometry in the photosensitization phenomena will be discussed in the context of new materials for solar-cells applications. (Full text)

  3. XAS study of TiO2-based nanomaterials

    Science.gov (United States)

    Schneider, K.; Zajac, D.; Sikora, M.; Kapusta, Cz.; Michalow-Mauke, K.; Graule, Th.; Rekas, M.

    2015-07-01

    X-Ray Absorption Spectroscopy studies of the W (0-1 at% W) and Mo-doped TiO2 (0-1 at% Mo) nanoparticle specimens at the K edges of titanium and molybdenum as well as at the L2 L3 edges of tungsten are presented. The materials were prepared with Flame Spray Synthesis process by oxidation of metal-organic precursors. The Ti:K edge spectra in the XANES range show pre-edge and post-edge features characteristic for anatase. A decrease of the amplitude of the EXAFS function with doping is observed and attributed to a softening of the crystal lattice. The Mo EXAFS functions show a considerable decrease of the second-neighbour-shell peak with increasing Mo content, which is attributed to an increased number of cation vacancies. For tungsten a less pronounced effect is observed. The Mo and W XANES spectra do not show noticeable changes with doping level, which indicates their unchanged oxidation states.

  4. Optical spectroscopy of rare earth ion-doped TiO2 nanophosphors.

    Science.gov (United States)

    Chen, Xueyuan; Luo, Wenqin

    2010-03-01

    Trivalent rare-earth (RE3+) ion-doped TiO2 nanophosphors belong to one kind of novel optical materials and have attracted increasing attention. The luminescence properties of different RE3+ ions in various TiO2 nanomaterials have been reviewed. Much attention is paid to our recent progresses on the luminescence properties of RE3+ (RE = Eu, Er, Sm, Nd) ions in anatase TiO2 nanoparticles prepared by a sol-gel-solvothermal method. Using Eu3+ as a sensitive optical probe, three significantly different luminescence centers of Eu3+ in TiO2 nanoparticles were detected by means of site-selective spectroscopy at 10 K. Based on the crystal-field (CF) splitting of Eu3+ at each site, C2v and D2 symmetries were proposed for Eu3+ incorporated at two lattice sites. A structural model for the formation of multiple sites was proposed based on the optical behaviors of Eu3+ at different sites. Similar multi-site luminescence was observed in Sm(3+)- or Nd(3+)-doped TiO2 nanoparticles. In Eu(3+)-doped TiO2 nanoparticles, only weak energy transfer from the TiO2 host to the Eu3+ ions was observed at 10 K due to the mismatch of energy between the TiO2 band-gap and the Eu3+ excited states. On the contrary, efficient host-sensitized luminescences were realized in Sm(3+)- or Nd(3+)-doped anatase TiO2 nanoparticles due to the match of energy between TiO2 band-gap and the Sm3+ and Nd3+ excited states. The excitation spectra of both Sm(3+)- and Nd(3+)-doped samples exhibit a dominant broad peak centered at approximately 340 nm, which is associated with the band-gap of TiO2, indicating that sensitized emission is much more efficient than direct excitation of the Sm3+ and Nd3+ ions. Single lattice site emission of Er3+ in TiO2 nanocrystals can be achieved by modifying the experimental conditions. Upon excitation by a Ti: sapphire laser at 978 nm, intense green upconverted luminescence was observed. The characteristic emission of Er3+ ions was obtained both in the ultraviolet-visible (UV-vis) and near-infrared regions through the high-resolution experiments at 10 K. The CF experienced by Er3+ in TiO2 nanocrystal was systematically studied by means of the energy level fitting.

  5. In situ controlled synthesis of various TiO2 nanostructured materials via a facile hydrothermal route

    International Nuclear Information System (INIS)

    Wang Hai; Liu Yong; Zhong Minyi; Xu Hongmei; Huang Hong; Shen Hui

    2011-01-01

    Various TiO 2 nanomaterials, such as nanosheets, nanoflowers, and nanowires were directly self assembled on titanium substrate on a large scale under hydrothermal conditions. The morphology of the formed TiO 2 nanomaterials could be easily tuned by varying the experimental parameters of temperature, reaction time, and the NaOH concentration. A possible formation mechanism was suggested on the basis of the shape evolution of TiO 2 nanostructures by SEM images in combination with XRD patterns of as-grown samples. The optical properties of TiO 2 nanosheets, nanoflowers, and nanowires were characterized by reflectance spectroscopy. The studies revealed that the absorption capability of visible light is obviously different for TiO 2 with different morphologies. Moreover, TiO 2 nanosheets exhibited better light trapping than TiO 2 nanoflowers and TiO 2 nanowires due to their unique nanostructure.

  6. Laser induced photocurrent and photovoltage transient measurements of dye-sensitized solar cells based on TiO_2 nanosheets and TiO_2 nanoparticles

    International Nuclear Information System (INIS)

    Ghaithan, Hamid M.; Qaid, Saif M.H.; Hezam, Mahmoud; Labis, Joselito P.; Alduraibi, Mohammad; Bedja, Idriss M.; Aldwayyan, Abdullah S.

    2016-01-01

    Dye-sensitized solar cells (DSSCs) based on TiO_2 nanoparticles and TiO_2 nanosheets with exposed {001} facets are investigated using laser-induced photovoltage and photocurrent transient decay (LIPVCD) measurements. We adopted a simplified version of LIPVCD technique, in which a single illumination light source and a laboratory oscilloscope could be conveniently used for the measurements. Although the {001} surface of TiO_2 nanosheets allowed a noticeably slower recombination with the electrolyte, this was counterpoised by a slower electron transport probably due to its planar morphology, resulting in a shorter diffusion length in TiO_2 nanosheets. The nanosheet morphology also resulted in less surface area and therefore reduced short circuit current density in the fabricated devices. Our work highlights the fact that the morphological parameters of TiO_2 nanosheets finally resulting after electrode film deposition is of no less importance than the reported efficient dye adsorption and slow electron recombination at the surface of individual nanosheets.

  7. Disruption of Autolysis in Bacillus subtilis using TiO2 Nanoparticles.

    Science.gov (United States)

    McGivney, Eric; Han, Linchen; Avellan, Astrid; VanBriesen, Jeanne; Gregory, Kelvin B

    2017-03-17

    In contrast to many nanotoxicity studies where nanoparticles (NPs) are observed to be toxic or reduce viable cells in a population of bacteria, we observed that increasing concentration of TiO 2 NPs increased the cell survival of Bacillus subtilis in autolysis-inducing buffer by 0.5 to 5 orders of magnitude over an 8 hour exposure. Molecular investigations revealed that TiO 2 NPs prevent or delay cell autolysis, an important survival and growth-regulating process in bacterial populations. Overall, the results suggest two potential mechanisms for the disruption of autolysis by TiO 2 NPs in a concentration dependent manner: (i) directly, through TiO 2 NP deposition on the cell wall, delaying the collapse of the protonmotive-force and preventing the onset of autolysis; and (ii) indirectly, through adsorption of autolysins on TiO 2 NP, limiting the activity of released autolysins and preventing further lytic activity. Enhanced darkfield microscopy coupled to hyperspectral analysis was used to map TiO 2 deposition on B. subtilis cell walls and released enzymes, supporting both mechanisms of autolysis interference. The disruption of autolysis in B. subtilis cultures by TiO 2 NPs suggests the mechanisms and kinetics of cell death may be influenced by nano-scale metal oxide materials, which are abundant in natural systems.

  8. Adsorption and photodegradation of methylene blue on TiO_2-halloysite adsorbents

    International Nuclear Information System (INIS)

    Du, Yuanyuan; Zheng, Pengwu

    2014-01-01

    TiO_2-halloysite (TiO_2-HNT) composites were fabricated by depositing anatase TiO_2 on the halloysite (HNT) surfaces with calcination treatment at 100, 200, 300 and 500 .deg. C. The obtained composites were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-Ray diffraction (XRD). HNT was attached with TiO_2 particles or clusters in sizes of 10-30 nm. With the increasing of calcination temperature, the crystalline of anatase became more perfect, but the structure of HNT could be destroyed at 500 .deg. C. The adsorption and photodegradation of methylene blue (MB) by TiO_2-HNTs were investigated. The kinetic adsorption fit the pseudo second-order, and the isotherm data followed the Langmuir model. The maximum adsorption capacities of MB were in the range of 38.57 to 54.29 mg/g. TiO_2-HNTs exhibited an efficient photocatalytic activity in the decomposition of MB. For TiO_2-HNT calcined at 300 .deg. C, 81.6% MB were degraded after 4 h treatment of UV irradiation

  9. High-performance thermoelectric materials based on ternary TiO2/CNT/PANI composites.

    Science.gov (United States)

    Erden, Fuat; Li, Hui; Wang, Xizu; Wang, FuKe; He, Chaobin

    2018-04-04

    In the present work, we report the fabrication of high-performance thermoelectric materials using TiO2/CNT/PANI ternary composites. We showed that a conductivity of ∼2730 S cm-1 can be achieved for the binary CNT (70%)/PANI (30%) composite, which is the highest recorded value for the reported CNT/PANI composites. We further demonstrated that the Seebeck coefficient of CNT/PANI composites could be enhanced by incorporating TiO2 nanoparticles into the binary CNT/PANI composites, which could be attributed to lower carrier density and the energy scattering of low-energy carriers at the interfaces of TiO2/a-CNT and TiO2/PANI. The resulting TiO2/a-CNT/PANI ternary system exhibits a higher Seebeck coefficient and enhanced thermoelectric power. Further optimization of the thermoelectric power was achieved by water treatment and by tuning the processing temperature. A high thermoelectric power factor of 114.5 μW mK-2 was obtained for the ternary composite of 30% TiO2/70% (a-CNT (70%)/PANI (30%)), which is the highest reported value among the reported PANI based ternary composites. The improvement of thermoelectric performance by incorporation of TiO2 suggests a promising approach to enhance power factor of organic thermoelectric materials by judicial tuning of the carrier concentration and electrical conductivity.

  10. Toxicity of nanotitanium dioxide (TiO2-NP) on human monocytes and their mitochondria.

    Science.gov (United States)

    Ghanbary, Fatemeh; Seydi, Enaytollah; Naserzadeh, Parvaneh; Salimi, Ahmad

    2018-03-01

    The effect of nanotitanium dioxide (TiO 2 -NP) in human monocytes is still unknown. Therefore, an understanding of probable cytotoxicity of TiO 2 -NP on human monocytes and underlining the mechanisms involved is of significant interest. The aim of this study was to assess the cytotoxicity of TiO 2 -NP on human monocytes. Using biochemical and flow cytometry assessments, we demonstrated that addition of TiO 2 -NP at 10 μg/ml concentration to monocytes induced cytotoxicity following 12 h. The TiO 2 -NP-induced cytotoxicity on monocytes was associated with intracellular reactive oxygen species (ROS) generation, mitochondrial membrane potential (MMP) collapse, lysosomal membrane injury, lipid peroxidation, and depletion of glutathione. According to our results, TiO 2 -NP triggers oxidative stress and organelles damages in monocytes which are important cells in defense against foreign agents. Finally, our findings suggest that use of antioxidants and mitochondrial/lysosomal protective agents could be of benefit for the people in the exposure with TiO 2 -NP.

  11. Single-Nanoparticle Photoelectrochemistry at a Nanoparticulate TiO2 -Filmed Ultramicroelectrode.

    Science.gov (United States)

    Peng, Yue-Yi; Ma, Hui; Ma, Wei; Long, Yi-Tao; Tian, He

    2018-03-26

    An ultrasensitive photoelectrochemical method for achieving real-time detection of single nanoparticle collision events is presented. Using a micrometer-thick nanoparticulate TiO 2 -filmed Au ultra-microelectrode (TiO 2 @Au UME), a sub-millisecond photocurrent transient was observed for an individual N719-tagged TiO 2 (N719@TiO 2 ) nanoparticle and is due to the instantaneous collision process. Owing to a trap-limited electron diffusion process as the rate-limiting step, a random three-dimensional diffusion model was developed to simulate electron transport dynamics in TiO 2 film. The combination of theoretical simulation and high-resolution photocurrent measurement allow electron-transfer information of a single N719@TiO 2 nanoparticle to be quantified at single-molecule accuracy and the electron diffusivity and the electron-collection efficiency of TiO 2 @Au UME to be estimated. This method provides a test for studies of photoinduced electron transfer at the single-nanoparticle level. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. SAXS Studies of TiO2 Nanoparticles in Polymer Electrolytes and in Nanostructured Films

    Directory of Open Access Journals (Sweden)

    Sigrid Bernstorff

    2010-11-01

    Full Text Available Polymer electrolytes as nanostructured materials are very attractive components for batteries and opto-electronic devices. (PEO8ZnCl2 polymer electrolytes were prepared from PEO and ZnCl2. The nanocomposites (PEO8ZnCl2/TiO2 themselves contained TiO2 nanograins. In this work, the influence of the TiO2 nanograins on the morphology and ionic conductivity of the nanocomposite was systematically studied by transmission small-angle X-ray scattering (SAXS simultaneously recorded with wide-angle X-ray diffraction (WAXD and differential scanning calorimetry (DSC at the synchrotron ELETTRA. Films containing nanosized grains of titanium dioxide (TiO2 are widely used in the research of optical and photovoltaic devices. The TiO2 films, prepared by chemical vapor deposition and e-beam epitaxy, were annealed in hydrogen atmospheres in the temperature range between 20 °C and 900 °C in order to study anatase-rutile phase transition at 740 °C. Also, grazing-incidence small angle X-ray scattering (GISAXS spectra for each TiO2 film were measured in reflection geometry at different grazing incident angles. Environmentally friendly galvanic cells, as well as solar cells of the second generation, are to be constructed with TiO2 film as working electrode, and nanocomposite polymer as electrolyte.

  13. Simplified TiO2 force fields for studies of its interaction with biomolecules

    Science.gov (United States)

    Luan, Binquan; Huynh, Tien; Zhou, Ruhong

    2015-06-01

    Engineered TiO2 nanoparticles have been routinely applied in nanotechnology, as well as in cosmetics and food industries. Despite active experimental studies intended to clarify TiO2's biological effects, including potential toxicity, the relation between experimentally inferred nanotoxicity and industry standards for safely applying nanoparticles remains somewhat ambiguous with justified concerns. Supplemental to experiments, molecular dynamics simulations have proven to be efficacious in investigating the molecular mechanism of a biological process occurring at nanoscale. In this article, to facilitate the nanotoxicity and nanomedicine research related to this important metal oxide, we provide a simplified force field, based on the original Matsui-Akaogi force field but compatible to the Lennard-Jones potentials normally used in modeling biomolecules, for simulating TiO2 nanoparticles interacting with biomolecules. The force field parameters were tested in simulating the bulk structure of TiO2, TiO2 nanoparticle-water interaction, as well as the adsorption of proteins on the TiO2 nanoparticle. We demonstrate that these simulation results are consistent with experimental data/observations. We expect that simulations will help to better understand the interaction between TiO2 and molecules.

  14. Titanium Dioxide (TiO2) Dye-Sensitized Solar Cells

    Science.gov (United States)

    Alseadi, Anwar Abdulaziz

    With the increasing global energy consumption and diminishing fossil fuels, various renewable and sustainable energies have been harvested in past decades and related devices have been fabricated. Dye-sensitized solar cells (DSSCs) are the most efficient third-generation solar cells to harvest solar energy into electricity directly. Titanium dioxide (TiO2) based DSSCs were invented in 1988 and have attracted more and more attention since then because of low-cost and high efficiency. TiO2 nanoparticles are one kind of popular anode materials of DSSC because of stability, abundance, environment safety, non-toxicity, and excellent photovoltaic properties. In the project, TiO2 nanoparticles with different crystallographic sizes were produced by ball-milling. Physical properties of the produced TiO 2 nanoparticles were characterized by X-ray powder diffraction, UV-visible spectroscopy, and Raman scattering. TiO2-based DSSCs were fabricated and their photovoltaic performances were tested. The effects of TiO2 layer thickness, crystallographic size, and microsphere fillings were investigated. The project enriched our understanding of TiO2-based DSSCs.

  15. Enhanced Photocatalytic Properties of Ag-Loaded N-Doped Tio2 Nanotube Arrays

    Directory of Open Access Journals (Sweden)

    Gao Dawei

    2018-03-01

    Full Text Available Highly ordered TiO2 nanotube (TiO2 NT arrays were prepared by anodic oxidizing method on the surface of the Ti substrate. Nitrogen-doped TiO2 nanotube (N-TiO2 NT arrays were carried out by ammonia solution immersion, and Ag nanoparticles loaded N-doped TiO2 nanotube (Ag/N-TiO2 NT arrays were obtained by successive ionic layer adsorption and reaction (SILAR technique. The samples were characterized by the X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, field emission scanning electron microscopy (FESEM, high-resolution transmission electron microscopy (HRTEM, photoluminescence (PL emission spectra, ultraviolet–visible (UV–vis diffuse reflectance spectroscopy (DRS. The result indicated that the diameter and wall thickness of the TiO2 NT are 100–120 and 20–30 nm, respectively. Moreover, the morphology and structure of the highly ordered TiO2 NTs were not affected by N-doping. Furthermore, Ag nanoparticles were evenly deposited on the surface of TiO2 NTs in the form of elemental silver. Finally, the photocatalytic activity of Ag/N-TiO2 NTs was evaluated by degradation of methyl orange (MO under visible-light irradiation. The Ag/N-TiO2 NTs exhibited enhanced photocatalytic properties, which could reach 95% after 90-min irradiation.

  16. Decolorization of dyeing wastewater in continuous photoreactors using tio2 coated glass tube media

    Directory of Open Access Journals (Sweden)

    Jutaporn Chanathaworn

    2014-02-01

    Full Text Available The present study deals with a decolorization development of malachite green (MG dyeing wastewater using TiO2 thin films coated glass tube media in photoreactor. The TiO2 photocatalyst was synthesized by three methods: TTIP sol-gel, TiO2 powder-modified sol, and TiO2 powder suspension coating on raschig ring glass tube media and was investigated crystallinity phase by SEM, XRD, and AFM. Degradation kinetics of the dyeing wastewater by photocatalytic was carried out under UV light irradiation. The Langmuir first-order model provided the best fit to the experimental data. The catalyst prepared by powder suspension technique and coated on glass tube had given the highest of decolorization kinetics and efficiency. Continuous photoreactor packed with the TiO2 coating media was designed and proven to be the high effectiveness for MG dyeing degradation and stable throughout the recyclability test. The light intensity, dye solution flow rate, and TiO2 loading were the most important parameters that response to decolorization efficiency. The optimum condition of photo decolorization of MG dye solution can be obtained from RSM model. Effectiveness of the synthesized TiO2 thin films using suspension technique and the continuous photoreactor design were obtained with a great potential to be proven for wastewater treatment at industrial scale.

  17. Light-induced antifungal activity of TiO2 nanoparticles/ZnO nanowires

    International Nuclear Information System (INIS)

    Haghighi, N.; Abdi, Y.; Haghighi, F.

    2011-01-01

    Antifungal activity of TiO 2 /ZnO nanostructures under visible light irradiation was investigated. A simple chemical method was used to synthesize ZnO nanowires. Zinc acetate dihydrate, Polyvinyl Pyrrolidone and deionized water were used as precursor, capping and solvent, respectively. TiO 2 nanoparticles were deposited on ZnO nanowires using an atmospheric pressure chemical vapor deposition system. X-ray diffraction pattern of TiO 2 /ZnO nano-composite has represented the diffraction peaks relating to the crystal planes of the TiO 2 (anatase and rutile) and ZnO. TiO 2 /ZnO nanostructure antifungal effect on Candida albicans biofilms was studied and compared with the activity of TiO 2 nanoparticles and ZnO nanowires. The high efficiency photocatalytic activity of TiO 2 nanoparticles leads to increased antifungal activity of ZnO nanowires. Scanning electron microscope was utilized to study the morphology of the as prepared nanostructures and the degradation of the yeast.

  18. Enhanced properties of nanostructured TiO2-graphene composites by rapid sintering

    Science.gov (United States)

    Shon, In-Jin; Yoon, Jin-Kook; Hong, Kyung-Tae

    2018-01-01

    Despite of many attractive properties of TiO2, the drawback of TiO2 ceramic is low fracture toughness for widely industrial application. The method to improve the fracture toughness and hardness has been reported by addition of reinforcing phase to fabricate a nanostructured composite. In this regard, graphene has been evaluated as an ideal second phase in ceramics. Nearly full density of nanostructured TiO2-graphene composite was achieved within one min using pulsed current activated sintering. The effect of graphene on microstructure, fracture toughness and hardness of TiO2-graphene composite was evaluated using Vickers hardness tester and field emission scanning electron microscopy. The grain size of TiO2 in the TiO2-x vol% (x = 0, 1, 3, and 5) graphene composite was greatly reduced with increase in addition of graphene. Both hardness and fracture toughness of TiO2-graphene composites simultaneously increased in the addition of graphene.

  19. ALMA observations of TiO2 around VY Canis Majoris

    Science.gov (United States)

    De Beck, E.; Vlemmings, W.; Muller, S.; Black, J. H.; O'Gorman, E.; Richards, A. M. S.; Baudry, A.; Maercker, M.; Decin, L.; Humphreys, E. M.

    2015-08-01

    Context. Titanium dioxide, TiO2, is a refractory species that could play a crucial role in the dust-condensation sequence around oxygen-rich evolved stars. To date, gas phase TiO2 has been detected only in the complex environment of the red supergiant VY CMa. Aims: We aim to constrain the distribution and excitation of TiO2 around VY CMa in order to clarify its role in dust formation. Methods: We analyse spectra and channel maps for TiO2 extracted from ALMA science verification data. Results: We detect 15 transitions of TiO2, and spatially resolve the emission for the first time. The maps demonstrate a highly clumpy, anisotropic outflow in which the TiO2 emission likely traces gas exposed to the stellar radiation field. An accelerating bipolar-like structure is found, oriented roughly east-west, of which the blue component runs into and breaks up around a solid continuum component. A distinct tail to the south-west is seen for some transitions, consistent with features seen in the optical and near-infrared. Conclusions: We find that a significant fraction of TiO2 remains in the gas phase outside the dust-formation zone and suggest that this species might play only a minor role in the dust-condensation process around extreme oxygen-rich evolved stars like VY CMa. Appendix A is available in electronic form at http://www.aanda.org

  20. Photocatalytic degradation of Rhodamine B dye using Fe doped TiO2 nanocomposites

    Science.gov (United States)

    Barkhade, Tejal; Banerjee, Indrani

    2018-05-01

    The unique properties of titanium dioxide (TiO2) such as high photo catalytic activity, high chemical stability and low toxicity have made it a suitable photocatalyst in recent decades. The effect of modification of TiO2 with doping of iron on its characteristics and photo catalytic efficiency was studied. The change in band gap energy of TiO2 nanoparticles after doping with Fe has been studied. Significant enhancement in photo catalytic property of TiO2 after Fe doping under light exposure conditions has been investigated. Acute exposure to non-biodegradable Rhodamine B resulted in many health problems like burning of eyes, skin irritation, nasal burning, and chest pain etc. Therefore, degradation of this dye is needed to save environment and animals. Considering the similar radius of Fe3+ and Ti4+ ions (respectively 0.64 Å and 0.68 Å), titanium position in the lattice of TiO2 can be replaced by iron cations easily. The undoped and Fe doped TiO2 nano composites were synthesized by sol-gel method, in which 1.0M% of Fe was doped with TiO2 and then the samples were characterized by using FE-SEM, UV-Visible diffuse spectroscopy, Raman Spectroscopy, and FTIR. Photo catalytic degradation of Rhodamine B dye experiment was carried out in visible light range. After 90 min time duration pink colour of dye turned colourless, indicating significant degradation rate with time.

  1. Photocatalytic oxidative desulfurization of dibenzothiophene catalyzed by amorphous TiO2 in ionic liquid

    International Nuclear Information System (INIS)

    Zhu, Wenshuai; Xu, Yehai; Li, Huaming; Dai, Bilian; Xu, Hui; Wang, Chao; Chao, Yanhong; Liu, Hui

    2014-01-01

    Three types of TiO 2 were synthesized by a hydrolysis and calcination method. The catalysts were characterized by X-ray powder diffraction (XRD), diffuse reflectance spectrum (DRS), Raman spectra, and X-ray photoelectron spectroscopy (XPS). The XRD and Raman spectra indicated that amorphous TiO 2 was successfully obtained at 100 .deg. C. The results indicated that amorphous TiO 2 achieved the highest efficiency of desulfurization. The photocatalytic oxidation of dibenzothiophene (DBT), benzothiophene (BT), 4,6-dimethyldibenzothiophene (4,6-DMDBT) and dodecanethiol (RSH) in model oil was studied at room temperature (30 .deg. C) with three catalysts. The system contained amorphous TiO 2 , H 2 O 2 , and [Bmim]BF 4 ionic liquid, ultraviolet (UV), which played vitally important roles in the photocatalytic oxidative desulfurization. Especially, the molar ratio of H 2 O 2 and sulfur (O/S) was only 2 : 1, which corresponded to the stoichiometric reaction. The sulfur removal of DBT-containing model oil with amorphous TiO 2 could reach 96.6%, which was apparently superior to a system with anatase TiO 2 (23.6%) or with anatase - rutile TiO 2 (18.2%). The system could be recycled seven times without a signicant decrease in photocatalytic activity

  2. NOx photocatalytic degradation on gypsum plates modified by TiO2-N,C photocatalysts

    Directory of Open Access Journals (Sweden)

    Janus Magdalena

    2015-09-01

    Full Text Available In presented studies the photocatalytic decomposition of NOx on gypsum plates modified by TiO2-N,Cphotocatalysts were presented. The gypsum plates were obtained by addition of 10 or 20 wt.% of different types of titanium dioxide, such as: pure TiO2 and carbon and nitrogen co-modified TiO2 (TiO2-N,C to gypsum. TiO2-N,C photocatalysts were obtained by heating up the starting TiO2 (Grupa Azoty Zakłady Chemiczne Police S.A in the atmosphere of ammonia and carbon at the temperature: 100, 300 i 600ºC. Photocatalyst were characterized by FTIR/DRS, UVVis/DR, BET and XRD methods. Moreover the compressive strength tests of modified gypsum were also done. Photocatalytic activity of gypsum plates was done during NOx decomposition. The highest photocatalytic activity has gypsum with 20 wt.% addition of TiO2-N,C obtained at 300ºC.

  3. Facile synthesis of porous TiO_2 photocatalysts using waste sludge as the template

    International Nuclear Information System (INIS)

    Wang, Xiaopeng; Huang, Shouqiang; Zhu, Nanwen; Lou, Ziyang; Yuan, Haiping

    2015-01-01

    Graphical abstract: Waste sludge is introduced to synthesize the waste sludge templated TiO_2 photocatalyst with porous structure, which possesses better photocatalytic activity compared to pure TiO_2. - Highlights: • Waste sludge is introduced to synthesize the TiO_2 photocatalyst. • Waste sludge templated TiO_2 sample possesses porous structure. • Waste sludge templated TiO_2 sample exhibits high photocatalytic activity. - Abstract: A resource utilization method of waste sludge is present by the synthesis of waste sludge templated TiO_2 photocatalysts. The organic materials in waste sludge are used as the pore-forming agents, and the transition metals included in the remaining waste sludge through calcination (WSC) can serve as the dopants for the WSC-TiO_2 (WSCT) photocatalyst. The visible and UV–visible light driven photocatalytic activities of WSCT are much better compared to those of pure TiO_2 and WSC, and it is originated from the higher light absorption property and the efficient electron–hole pair separation provided by waste sludge.

  4. Probing Photocatalytic Characteristics of Sb-Doped TiO2 under Visible Light Irradiation

    Directory of Open Access Journals (Sweden)

    Lingjing Luo

    2014-01-01

    Full Text Available Sb-doped TiO2 nanoparticle with varied dopant concentrations was synthesized using titanium tetrachloride (TiCl4 and antimony chloride (SbCl3 as the precursors. The properties of Sb-doped TiO2 nanoparticles were characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, fluorescence spectrophotometer, and Uv-vis spectrophotometer. The absorption edge of TiO2 nanoparticles could be extended to visible region after doping with antimony, in contrast to the UV absorption of pure TiO2. The results showed that the photocatalytic activity of Sb-doped TiO2 nanoparticles was much more active than pure TiO2. The 0.1% Sb-doped TiO2 nanoparticles demonstrated the best photocatalytic activity which was better than that of the Degussa P25 under visible light irradiation using terephthalic acid as fluorescent probe. The effects of Sb dopant on the photocatalytic activity and the involved mechanism were extensively investigated in this work as well.

  5. W-doped TiO2 photoanode for high performance perovskite solar cell

    International Nuclear Information System (INIS)

    Liu, Jinwang; Zhang, Jing; Yue, Guoqiang; Lu, Xingwei; Hu, Ziyang; Zhu, Yuejin

    2016-01-01

    Titanium dioxide (TiO 2 ) with dispersed W-doping shows its capability for efficient electron collection from perovskite to TiO 2 in perovskite solar cell. The conduction band (CB) of TiO 2 moves downward (positive shift) with increasing the tungsten (W) content, which enlarges the energy gap between the CB of TiO 2 and the perovskite. Thus, the efficiency of electron injection from perovskite to TiO 2 is increased. Due to the increased electron injection, W-doped TiO 2 (≤0.2% W content) enhances the short-circuit photocurrent (J sc ) of perovskite solar cell and improves the performance of perovskite solar cell. Perovskite solar cell with 0.1% W-doped photoanode obtains the highest power conversion efficiency (η = 10.6%), which shows enhancement by 13% in J sc and by 17% in η, as compared with the undoped TiO 2 perovskite solar cell.

  6. TiO2 nanoparticle biosynthesis and its physiological effect on mung bean (Vigna radiata L.

    Directory of Open Access Journals (Sweden)

    Ramesh Raliya

    2015-03-01

    Full Text Available TiO2 nanoparticle (NPs biosynthesis is a low cost, ecofriendly approach developed using the fungi Aspergillus flavus TFR 7. To determine whether TiO2 NPs is suitable for nutrient, we conducted a two part study; biosynthesis of TiO2 NP and evaluates their influence on mung bean. The characterized TiO2 NPs were foliar sprayed at 10 mgL−1 concentration on the leaves of 14 days old mung bean plants. A significant improvement was observed in shoot length (17.02%, root length (49.6%, root area (43%, root nodule (67.5%, chlorophyll content (46.4% and total soluble leaf protein (94% as a result of TiO2 NPs application. In the rhizosphere microbial population increased by 21.4–48.1% and activity of acid phosphatase (67.3%, alkaline phosphatase (72%, phytase (64% and dehydrogenase (108.7% enzyme was observed over control in six weeks old plants owing to application of TiO2 NPs. A possible mechanism has also been hypothesized for TiO2 NPs biosynthesis.

  7. Enhanced photocatalytic activity of wool-ball-like TiO2 microspheres on carbon fabric and FTO substrates

    Science.gov (United States)

    Zhang, Yu; Gu, Jian; Zhang, Mengqi

    2018-06-01

    The wool-ball-like TiO2 microspheres on carbon fabric (TiO2-CF) and FTO substrates (TiO2-FTO) have been synthesized by a facile hydrothermal method in alkali environment, using commercial TiO2 (P25) as precursors. The XRD results indicate that the as-prepared TiO2 have good crystallinity. And the SEM images show that the wool-ball-like TiO2 microspheres with a diameter of 2-3 μm are composed of TiO2 nanowires, which have a diameter of 50 nm. The photocatalytic behavior of the wool-ball-like TiO2 microspheres, TiO2-CF and TiO2-FTO under ultraviolet light was investigated by a pseudo first-order kinetic model, using methyl orange (MO) as pollutant. The wool-ball-like TiO2 microspheres obtained a degradation rate constant (Kap) of 6.91×10-3 min-1 . The Kap values of TiO2-FTO and TiO2-CF reach 13.97×10-3 min-1 and 11.80×10-3 min-1, which are 2.0 and 1.7 times higher than that of pristine wool-ball-like TiO2 microspheres due to the "sum effect" between TiO2 and substrates. This study offers a facile hydrothermal method to prepare wool-ball-like TiO2 microspheres on CF and FTO substrates, which will improve the recyclability of phtocatalysts and can be extended to other fields.

  8. Photocatalytic and microwave absorbing properties of polypyrrole/Fe-doped TiO2 composite by in situ polymerization method

    International Nuclear Information System (INIS)

    Li Qiaoling; Zhang Cunrui; Li Jianqiang

    2011-01-01

    Research highlights: → Polypyrrole/Fe-doped TiO 2 composite is prepared by in situ polymerization of pyrrole on the Fe-doped TiO 2 template. → The Fe-doped TiO 2 microbelts are prepared by sol-gel method using the absorbent cotton template for the first time. → Then the Fe-doped TiO 2 microbelts are used as template for the preparation of polypyrrole/Fe-doped TiO 2 composites. → The structure, morphology and properties of the composites are characterized with scanning electron microscope (SEM), IR, Net-work Analyzer. → A possible formation mechanism of Fe-doped TiO 2 microbelts and polypyrrole/Fe-doped TiO 2 composites has been proposed. → The effect of the mol ratio of pyrrole/Fe-doped TiO 2 on the photocatalysis properties and microwave loss properties of the composites is investigated. - Abstract: The Fe-doped TiO 2 microbelts were prepared by sol-gel method using the absorbent cotton template for the first time. Then the Fe-doped TiO 2 microbelts were used as templates for the preparation of polypyrrole/Fe-doped TiO 2 composites. Polypyrrole/Fe-doped TiO 2 composites were prepared by in situ polymerization of pyrrole on the Fe-doped TiO 2 template. The structure, morphology and properties of the composites were characterized with scanning electron microscope (SEM), FTIR, Net-work Analyzer. The possible formation mechanisms of Fe-doped TiO 2 microbelts and polypyrrole/Fe-doped TiO 2 composites have been proposed. The effect of the molar ratio of pyrrole/Fe-doped TiO 2 on the photocatalytic properties and microwave loss properties of the composites was investigated.

  9. Effect of TiO_2 Loading on Pt-Ru Catalysts During Alcohol Electrooxidation

    International Nuclear Information System (INIS)

    Hasa, Bjorn; Kalamaras, Evangelos; Papaioannou, Evangelos I.; Vakros, John; Sygellou, Labrini; Katsaounis, Alexandros

    2015-01-01

    Highlights: • TiO_2 can be used to modify Pt-Ru based electrodes for alcohol oxidation. • TiO_2 modified electrodes with lower amount of metals had higher active surface area than pure Pt-Ru electrodes. • TiO_2 modified electrodes showed comparable performance with pure Pt-Ru electrode both in a single cell and in a PEM fuel cell under alcohol fuelling. - Abstract: In this study, Pt-Ru based electrodes modified by TiO_2 were prepared by means of thermal decomposition of chloride and isopropoxide precursors on Ti substrates, characterised by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), electrochemical techniques and CO stripping and used as anodes for alcohol oxidation. The minimization of the metal loading without electrocatalytic activity losses was also explored. TiO_2 was chosen due to its chemical stability, low cost and excellent properties as substrate for metal dispersion. It was found that TiO_2 loading up to 50% results in a 3-fold increase of the Electrochemically Active Surface (EAS). This conclusion has been confirmed by CO stripping experiments. All samples have been evaluated during the electrochemical oxidation of methanol, ethanol and glycerol. In all cases, the Pt_2_5-Ru_2_5-(TiO_2)_5_0 electrode had better electrocatalytic activity than the pure Pt_5_0-Ru_5_0 anode. The best modified electrode, (Pt_2_5-Ru_2_5-(TiO_2)_5_0), was also evaluated as anode in a PEM fuel cell under methanol fuelling conditions. The observed higher performance of the TiO_2 modified electrodes was attributed to the enhanced Pt-Ru dispersion as well as the formation of smaller Pt and Ru particles.

  10. Adsorption and Recovery of Polyphenolic Flavonoids Using TiO_2-Functionalized Mesoporous Silica Nanoparticles

    International Nuclear Information System (INIS)

    Khan, M. Arif; Wallace, William T.; Islam, Syed Z.; Nagpure, Suraj; Strzalka, Joseph

    2017-01-01

    Exploiting specific interactions with titania (TiO_2) has been proposed for the separation and recovery of a broad range of biomolecules and natural products, including therapeutic polyphenolic flavonoids which are susceptible to degradation, such as quercetin. Functionalizing mesoporous silica with TiO_2 has many potential advantages over bulk and mesoporous TiO_2 as an adsorbent for natural products, including robust synthetic approaches leading to high surface area, stable separation platforms. Here, TiO_2 surface functionalized mesoporous silica nanoparticles (MSNPs) are synthesized and characterized as a function of TiO_2 content (up to 636 mg TiO2/g). The adsorption isotherms of two polyphenolic flavonoids, quercetin and rutin, were determined (0.05-10 mg/ml in ethanol), and a 100-fold increase in the adsorption capacity was observed relative to functionalized nonporous particles with similar TiO_2 surface coverage. An optimum extent of functionalization (approximately 440 mg TiO_2/g particles) is interpreted from characterization techniques including grazing incidence x-ray scattering (GIXS), high resolution transmission electron microscopy (HRTEM) and nitrogen adsorption, which examined the interplay between the extent of TiO_2 functionalization and the accessibility of the porous structures. The recovery of flavonoids is demonstrated using ligand displacement in ethanolic citric acid solution (20% w/v), in which greater than 90% recovery can be achieved in a multistep extraction process. The radical scavenging activity (RSA) of the recovered and particle-bound quercetin as measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay demonstrates greater than 80% retention of antioxidant activity by both particle-bound and recovered quercetin. In conclusion, these mesoporous titanosilicate materials can serve as a synthetic platform to isolate, recover, and potentially deliver degradation-sensitive natural products to biological systems.

  11. TiO2-BASED Composite Films for the Photodegradation of Oxytetracycline

    Science.gov (United States)

    Li, Hui; Guan, Ling-Xiao; Feng, Ji-Jun; Li, Fang; Yao, Ming-Ming

    2015-02-01

    The spread of the antibiotic oxytetracycline (OTC) has been thought as a threat to the safety of drinking water. In this paper, the photocatalytic activity of the nanocrystalline Fe/Ca co-doped TiO2-SiO2 composite film for the degradation of OTC was studied. The films were characterized by field emission scanning electron microscopy (FE-SEM) equipped with energy-dispersive spectroscopy (EDS), N2 adsorption/desorption isotherms, photoluminescence (PL) spectra, and UV-Vis diffraction reflectance absorption spectra (DRS). The FE-SEM results indicated that the Fe/Ca co-doped TiO2-SiO2 film was composed of smaller nanoparticles compared to pure TiO2 or TiO2-SiO2 film. The BET surface area results showed that the specific surface area of the pure TiO2, TiO2-SiO2 and Ca2+/Fe3+ co-doped TiO2-SiO2 is 118.3 m2g-1, 294.3 m2g-1 and 393.7 m2g-1, respectively. The DRS and PL spectra revealed that the Fe/Ca co-doped TiO2-SiO2 film had strong visible light adsorption and diminished electrons/holes recombination. Experimental results showed that the Fe/Ca co-doped TiO2-SiO2 film is effective in the degradation of OTC under both UV and visible light irradiation.

  12. Preparation, Characterization and Analysis of Fouling Mechanisms of TiO2- Embedded PVDF Membranes

    Directory of Open Access Journals (Sweden)

    Yoones Jafarzadeh

    2017-01-01

    Full Text Available Titanium dioxide (TiO2-embedded polyvinylidene fluoride (PVDF mixed matrix membranes were prepared through a nonsolvent induced phase separation (NIPS method. The structure of the membranes was characterized by FESEM, EDX, water drop contact angle measurement, pure water flux and mean pore radius analysis. The results showed that the prepared membranes had asymmetric structures with macro-voids and the presence of TiO2 nanoparticles increased the size of macro-voids. Moreover, pure water flux increased from 41 kg/m2h to 162 kg/m2h the content of TiO2 nanoparticles increased from 1 wt% to 5 wt% as embedded membrane. The contact angle dropped from 100° for 1 wt% TiO2- embedded membrane to 69° for 5 wt% TiO2-embedded membrane, showing that the hydrophilicity of membranes increased by addition of inorganic TiO2 nanoparticles. The fouling behavior oftheprepared mixed matrix membranes was studied in filtration process of 1% humic acid solution. The results showed that fouling resistance of the membranes increased with higher content of TiO2 nanoparticles. The results of classic fouling modeling of membranes showed that for 2 and 5 wt% TiO2-embedded membranes the best fit of the data occurred with the intermediate blockage model whereas cake formation model was the dominant mechanism for other membranes. Moreover, the analysis of fouling mechanisms by combined models showed that cake filtration-intermediate blockage model was in good agreement with the experimental data for all membranes. Finally, the results showed that the rejection of membranes increased with the addition of TiO2 nanoparticles, and then decreased.

  13. Synthesis and photocatalytic activity of mesoporous – (001) facets TiO_2 single crystals

    International Nuclear Information System (INIS)

    Dong, Yeshuo; Fei, Xuening; Zhou, Yongzhu

    2017-01-01

    Highlights: • The (001) facets of TiO_2 single crystals with mesoporous structure. • The (010) and (100) facets of TiO_2 single crystals were covered by the flower – shaped TiO_2 crystals. • This special structure could promote charge separation and provide more active sites, which will lead to a substantial increase in photocatalytic activity. - Abstract: In this work, the mesoporous – (001) facets TiO_2 single crystals have been successfully synthesized through a two-step solvothermal route without any template. Their structure and morphology were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV–vis) diffuse reflectance spectroscopy and energy dispersive X-ray spectrometer (EDX). Based on the different characteristics and atomic arrangements on each facet of anatase TiO_2 single crystals, we synthesized these mesoporous – (001) facets TiO_2 single crystals by controlling the interaction characteristics of hydrofluoric acid (HF) and isopropanol (i-PrOH) on the crystal facets. It can been seen that the (001) facets of these as-synthesized TiO_2 single crystals have a clear mesoporous structure through the SEM images and BET methods. Moreover, the other four facets were covered by the flower – shaped TiO_2 crystals with the generation of the mesoporous – (001) facets. This special and interesting morphology could promote charge separation and provide more active sites, which will lead to a substantial increase in photocatalytic activity. Moreover, it is more intuitive to reflect that the different crystal facets possess the different properties due to their atomic arrangement. Besides, according to the different synthetic routes, we proposed and discussed a plausible synthesis mechanism of these mesoporous – (001) facets TiO_2 single crystals.

  14. Preparation and Characterization of Nano-Sized TiO2@Chitosan for Bone Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Lei JIANG

    2016-12-01

    Full Text Available Background: With the development of genetic engineering, it is urgent to find a vector with high transfection efficiency and good biocompatibility for genes. We considered combining nano-TiO2 with chitosan (CTS in order to tap their respective advantages to make a better new nanoparticle as gene vector.Methods: TiO2@CTS was prepared using microemulsion method. The physicochemical property of TiO2@CTS was measured by transmission electron microscopy (TEM and zeta potential. The safety and influence on MC3T3-E1 cells were detected by methyl thiazolyl tetrazolium (MTT, blood compatibility assay and flow cytometry.Results: TiO2@CTS was well prepared and it was safe to cells under concentration tests. TiO2@CTS particles had a fuzzy boundary with a particle size remaining in 20-30 nm. Besides, the results also showed that TiO2@CTS did better in cellular uptake than TiO2 at 2 h and 24 h, and had good biocompatibility. MTT assay proved that the MC3T3 cells remained good growth when treated with different concentrations of TiO2@CTS (2.5, 5, 10, 20, 40 and 80 μg/mL. Moreover, transfection assay in vitro and electrophoretic mobility shift assay illustrated the high transfection efficiency of TiO2@CTS.Conclusion: TiO2@CTS is a good choice to gene transfection, with good biocompatibility, and it also provides a new thought for the application of nanotechnology in the field of aveolar bone graft material.

  15. Liquid phase deposition of WO3/TiO2 heterojunction films with high photoelectrocatalytic activity under visible light irradiation

    International Nuclear Information System (INIS)

    Zhang, Man; Yang, Changzhu; Pu, Wenhong; Tan, Yuanbin; Yang, Kun; Zhang, Jingdong

    2014-01-01

    Highlights: • Liquid phase deposition is developed for preparing WO 3 /TiO 2 heterojunction films. • TiO 2 film provides an excellent platform for WO 3 deposition. • WO 3 expands the absorption band edge of TiO 2 film to visible light region. • WO 3 /TiO 2 heterojunction film shows high photoelectrocatalytic activity. - ABSTRACT: The heterojunction films of WO 3 /TiO 2 were prepared by liquid phase deposition (LPD) method via two-step processes. The scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopic analysis indicated that flower-like WO 3 film was successfully deposited on TiO 2 film with the LPD processes. The TiO 2 film provided an excellent platform for WO 3 deposition while WO 3 obviously expanded the absorption of TiO 2 film to visible light. As the result, the heterojunction film of WO 3 /TiO 2 exhibited higher photocurrent response to visible light illumination than pure TiO 2 or WO 3 film. The photoelectrocatalytic (PEC) activity of WO 3 /TiO 2 film was evaluated by degrading Rhodamin B (RhB) and 4-chlorophenol (4-CP) under visible light irradiation. The results showed that the LPD WO 3 /TiO 2 film possessed high PEC activity for efficient removal of various refractory organic pollutants

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

    DEFF Research Database (Denmark)

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

    2017-01-01

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

  17. Development and Application of TiO2 Nanoparticles Coupled with Silver Halide

    Directory of Open Access Journals (Sweden)

    Xiaojia Wan

    2014-01-01

    Full Text Available Titanium dioxide (TiO2 is proposed to be effective photocatalyst for wastewater treatment, air purification, and self-cleaning ability, because of its strong oxidation and superhydrophilicity. In order to conquer the limits of TiO2, a variety of methods have been used. This paper presents a critical review of novel research and achievements in the modification of TiO2 nanoparticles with silver halide (AgX, X=Cl, Br, I, which aims at enhancing the visible light absorption and photosensitivity. Herein we study the synthesis, physical and chemical properties, and the mechanism of this composite photocatalyst.

  18. TiO2-Anatase Nanowire Dispersed Composite Electrode for Dye-Sensitized Solar Cells

    International Nuclear Information System (INIS)

    Asagoe, K; Suzuki, Y; Ngamsinlapasathian, S; Yoshikawa, S

    2007-01-01

    TiO 2 anatase nanowires have been prepared by a hydrothermal process followed by post-heat treatment in air. TiO 2 nanoparticle/TiO 2 nanowire composite electrodes were prepared for dye-sensitized solar cells (DSC) in order to improve light-to-electricity conversion efficiency. The TiO 2 NP/TiO 2 NW composite cells showed higher DSC performance than ordinary nanoparticle cells and fully nanowire cells: efficiency (η = 6.53 % for DSC with 10% nanowire, whereas 5.59% for 0% nanowire, and 2.42% for 100% nanowire

  19. Fabrication and electrical characteristics for MIS diode by utilizing TiO2 ceramics

    International Nuclear Information System (INIS)

    Bae, S.H.

    1981-01-01

    Metal insulator semiconductor diodes were made by utilizing TiO 2 ceramics. Tunnel field emission is here proposed as a model for rectification in TiO 2 diode. Measurements of junction depth show very satisfactory agreement with value obtained from the Richardson plot, thus serving as additional supporting evidence of field emission in TiO 2 ceramic. The measured junction area exceeds by a factor of 10 6 the value expected by assuming field emission. The Richardson plot shows a deviation from the emission theory at low voltage, which is probably due to leakage currents which are present in MIS rutile diode. (author)

  20. Effective Removal of Congo Red by Triarrhena Biochar Loading with TiO2 Nanoparticles

    Directory of Open Access Journals (Sweden)

    Peng Yu

    2018-01-01

    Full Text Available A composite of pyrolytic Triarrhena biochar loading with TiO2 nanoparticles has been synthesized by the sol-gel method. The composite shows a well-developed hollow mesoporous and macropore structure as characterized by XRD, BET, and SEM. When used as an absorbent to remove Congo red from aqueous solution, it was found that as-prepared composite performed better absorption capacity than single biochar or TiO2. The results suggest that biochar loading with TiO2 could be promisingly implemented as an environmentally friendly and inexpensive adsorbent for Congo red removal from wastewater.

  1. Fabrication and characterization of mesoporous TiO2/polypyrrole-based nanocomposite for electrorheological fluid

    International Nuclear Information System (INIS)

    Wei Chuan; Zhu Yihua; Jin Yi; Yang Xiaoling; Li Chunzhong

    2008-01-01

    Mesoporous TiO 2 /polypyrrole (PPy)-based nanocomposite for electrorheological fluid was synthesized through one-pot method. By exploiting the combination conductivity of PPy and high dielectric constant of TiO 2 , the ER fluid exhibited an enhanced effect. The shear stress was 3.3 times as high as that of mesoporous TiO 2 . Powder X-ray diffraction (XRD), TEM and Fourier transform infrared (FT-IR) spectroscopy were employed to characterize the as-made samples. Using a modified rotational viscometer, the electrorheological effect was measured. Dielectric spectra were also given to explain the mechanism

  2. Photocatalytic Degradation of Methylene Blue Using TiO2 Impregnated Diatomite

    OpenAIRE

    Zuo, Ranfang; Du, Gaoxiang; Zhang, Weiwei; Liu, Lianhua; Liu, Yanming; Mei, Lefu; Li, Zhaohui

    2014-01-01

    Nano-TiO2 showed a good catalytic activity, but it is easy to agglomerate, resulting in the reduction or even complete loss of photocatalytic activity. The dispersion of TiO2 particles on porous materials was a potential solution to this problem. Diatomite has high specific surface and absorbability because of its particular shell structure. Thus, TiO2/diatomite composite, prepared by loading TiO2 on the surface of diatomite, was a good photocatalyst, through absorbing organic compounds with ...

  3. Carbon and TiO_2 synergistic effect on methylene blue adsorption

    International Nuclear Information System (INIS)

    Simonetti, Evelyn Alves Nunes; Simone Cividanes, Luciana de; Campos, Tiago Moreira Bastos; Rossi Canuto de Menezes, Beatriz; Brito, Felipe Sales; Thim, Gilmar Patrocínio

    2016-01-01

    Due to its high efficiency, low cost and a simple operation, the adsorption process is an important and widely used technique for industrial wastewater treatment. Recent studies on the removal of artificial dyes by adsorption include a large number of adsorbents, such as: activated carbon, silicates, carbon nanotube, graphene, fibers, titanates and doped titanates. The carbon insertion in the TiO_2 structure promotes a synergistic effect on the adsorbent composite, improving the adsorption and the charge-transfer efficiency rates. However, there are few studies regarding the adsorption capacity of TiO_2/Carbon composites with the carbon concentration. This study evaluates the effect of carbon (resorcinol/formaldehyde) insertion on TiO_2 structure through the adsorption process. Adsorbents were prepared by varying the carbon weight percentages using the sol-gel method. The physicochemical properties of the catalysts prepared, such as crystallinity, particle size, surface morphology, specific surface area and pore volume were investigated. The kinetic study, adsorption isotherm, pH effect and thermodynamic study were examined in batch experiments using methylene blue as organic molecule. In addition, the effect of carbon phase on the adsorption capacity of TiO_2-carbon composite was deeply investigated. SEM micrographs showed that TiO_2 phase grows along the carbon phase and FT-IR results showed the presence of Ti−O−C chemical bonding. The experiments indicate that the carbon phase acted as a nucleation agent for the growth of TiO_2 during the sol-gel step, with a TiO_2 structure suitable for blue methylene adsorption, resulting in a material with large surface area and slit-like or wedge-shaped pores. Further experiments will show the best carbon concentration for methylene blue adsorption using a TiO_2 based material. - Highlights: • This article deals with the adsorption of methylene blue onto TiO_2-Carbon composite. • The sol-gel synthesis was efficient to insert TiO_2 particles on carbon structure. • The TiO_2 nanoparticles presented mesopore area around the carbon structure. • The wedge shapes pores which were the main responsible for methylene blue removal. • A new TiO_2-Carbon materials can be used for removal of large pollutants molecules.

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

    International Nuclear Information System (INIS)

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

    2004-01-01

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

  5. ZnO nanorods/AZO photoanode for perovskite solar cells fabricated in ambient air

    Science.gov (United States)

    La Ferrara, Vera; De Maria, Antonella; Rametta, Gabriella; Della Noce, Marco; Vittoria Mercaldo, Lucia; Borriello, Carmela; Bruno, Annalisa; Delli Veneri, Paola

    2017-08-01

    ZnO nanorods are a good candidate for replacing standard photoanodes, such as TiO2, in perovskite solar cells and in principle superseding the high performances already obtained. This is possible because ZnO nanorods have a fast electron transport rate due to their large surface area. An array of ZnO nanorods is grown by chemical bath deposition starting from Al-doped ZnO (AZO) used both as a seed layer and as an efficient transparent anode in the visible spectral range. In particular, in this work we fabricate methylammonium lead iodide (CH3NH3PbI3) perovskite solar cells using glass/AZO/ZnO nanorods/perovskite/Spiro-OMeTAD/Au as the architecture. The growth of ZnO nanorods has been optimized by varying the precursor concentrations, growth time and solution temperature. All the fabrication process and photovoltaic characterizations have been carried out in ambient air and the devices have not been encapsulated. Power conversion efficiency as high as 7.0% has been obtained with a good stability over 20 d. This is the highest reported value to the best of our knowledge and it is a promising result for the development of perovskite solar cells based on ZnO nanorods and AZO.

  6. Photocatalytic degradation of paracetamol on TiO2 nanoparticles and TiO2/cellulosic fiber under UV and sunlight irradiation

    OpenAIRE

    Jallouli, Nabil; Elghniji, Kais; Trabelsi, Hassen; Ksibi, Mohamed

    2014-01-01

    In the present study, photocatalytic degradation of acetaminophen ((N-(4-hydroxyphe-nyl)acetamide)), an analgesic drug has been investigated in a batch reactor using TiO2 P25 as a photocatalyst in slurry and under UV light. Using TiO2 P25 nanoparticles, much faster photodegradation of paracetamol and effective mineralization occurred, more than 90% of 2.65 × 10−4 M paracetamol was degraded under UV irradiation. Changes in pH values affected the adsorption and the photodegradation of paracetam...

  7. Copper doping enhanced the oxidative stress-mediated cytotoxicity of TiO2 nanoparticles in A549 cells.

    Science.gov (United States)

    Ahmad, J; Siddiqui, M A; Akhtar, M J; Alhadlaq, H A; Alshamsan, A; Khan, S T; Wahab, R; Al-Khedhairy, A A; Al-Salim, A; Musarrat, J; Saquib, Q; Fareed, M; Ahamed, M

    2018-05-01

    Physicochemical properties of titanium dioxide nanoparticles (TiO 2 NPs) can be tuned by doping with metals or nonmetals. Copper (Cu) doping improved the photocatalytic behavior of TiO 2 NPs that can be applied in various fields such as environmental remediation and nanomedicine. However, interaction of Cu-doped TiO 2 NPs with human cells is scarce. This study was designed to explore the role of Cu doping in cytotoxic response of TiO 2 NPs in human lung epithelial (A549) cells. Characterization data demonstrated the presence of both TiO 2 and Cu in Cu-doped TiO 2 NPs with high-quality lattice fringes without any distortion. The size of Cu-doped TiO 2 NPs (24 nm) was lower than pure TiO 2 NPs (30 nm). Biological results showed that both pure and Cu-doped TiO 2 NPs induced cytotoxicity and oxidative stress in a dose-dependent manner. Low mitochondrial membrane potential and higher caspase-3 enzyme (apoptotic markers) activity were also observed in A549 cells exposed to pure and Cu-doped TiO 2 NPs. We further observed that cytotoxicity caused by Cu-doped TiO 2 NPs was higher than pure TiO 2 NPs. Moreover, antioxidant N-acetyl cysteine effectively prevented the reactive oxygen species generation, glutathione depletion, and cell viability reduction caused by Cu-doped TiO 2 NPs. This is the first report showing that Cu-doped TiO 2 NPs induced cytotoxicity and oxidative stress in A549 cells. This study warranted further research to explore the role of Cu doping in toxicity mechanisms of TiO 2 NPs.

  8. Graded core/shell semiconductor nanorods and nanorod barcodes

    Science.gov (United States)

    Alivisatos, A. Paul; Scher, Erik C.; Manna, Liberato

    2010-12-14

    Graded core/shell semiconductor nanorods and shaped nanorods are disclosed comprising Group II-VI, Group III-V and Group IV semiconductors and methods of making the same. Also disclosed are nanorod barcodes using core/shell nanorods where the core is a semiconductor or metal material, and with or without a shell. Methods of labeling analytes using the nanorod barcodes are also disclosed.

  9. Anti-fish bacterial pathogen effect of visible light responsive Fe3O4@TiO2 nanoparticles immobilized on glass using TiO2 sol–gel

    International Nuclear Information System (INIS)

    Yeh, N.; Lee, Y.C.; Chang, C.Y.; Cheng, T.C.

    2013-01-01

    This paper demonstrates a fish pathogen reduction procedure that uses TiO 2 sol–gel coating Fe 3 O 4 @TiO 2 powder on glass substrate. Such procedure can effectively relieve two constraints that haunt TiO 2 sterilization applications: 1) the need for UV for overcoming the wide band gap of pure TiO 2 and 2) the difficulty of its recovering from water for reuse. In the process, visible light responsive Fe 3 O 4 /TiO 2 nanoparticles are synthesized and immobilized on glass using TiO 2 sol–gel as the binder for fish bacterial pathogen disinfection test. After 3 h of visible light irradiation, the immobilized Fe 3 O 4 @TiO 2 's inhibition efficiencies for fish bacterial pathogen are, respectively, 50% for Edwardsiella tarda (BCRC 10670) and 23% for Aeromonas hydrophila (BCRC 13018)

  10. ELECTROPHORETIC DEPOSITION OF TIO2-MULTI-WALLED CARBON NANOTUBE COMPOSITE COATINGS: MORPHOLOGICAL STUDY

    Directory of Open Access Journals (Sweden)

    M. S. MAHMOUDI JOZEE

    2016-09-01

    Full Text Available A homogenous TiO2 / multi-walled carbon nanotubes(MWCNTs composite film were prepared by electrophoretic co-deposition from organic suspension on a stainless steel substrate.  In this study, MWCNTs was incorporated to the coating because of their long structure and their capability to be functionalized by different inorganic groups on the surface. FTIR spectroscopy showed the existence of carboxylic groups on the modified carbon nanotubes surface. The effect of applied electrical fields, deposition time and concentration of nanoparticulates on coatings morphology were investigated by scanning electron microscopy. It was found that combination of MWCNTs within TiO2 matrix eliminating micro cracks presented on TiO2 coating. Also, by increasing the deposition voltages, micro cracks were increased. SEM observation of the coatings revealed that TiO2/multi-walled carbon nanotubes coatings produced from optimized electric field was uniform and had good adhesive to the substrate.

  11. Effect of chemisorbed surface species on the photocatalytic activity of TiO2 nanoparticulate films

    International Nuclear Information System (INIS)

    Cao Yaan; Yang Wensheng; Chen Yongmei; Du Hui; Yue, Polock

    2004-01-01

    TiO 2 sols prepared in acidic and basic medium were deposited into films by a spin coating method. Photodegradation experiments showed that photocatalytic activity of the films prepared from acidic sol was much higher than that from basic sol. It is identified that there are more chemisorbed species of CO 2 on the surface of the TiO 2 films from the basic sol than on the surface of the TiO 2 films from the acidic sol. The chemisorbed species of CO 2 reduce the concentration of active species such as hydroxyl group and bridging oxygen on surface of the TiO 2 film and contribute to the formation of surface electron traps in the band gap which are detrimental to charge separation, thus lowering the photocatalytic activity

  12. The properties of transparent TiO2 films for Schottky photodetector

    Directory of Open Access Journals (Sweden)

    Sung-Ho Park

    2017-08-01

    Full Text Available In this data, the properties of transparent TiO2 film for Schottky photodetector are presented for the research article, entitled as “High-performing transparent photodetectors based on Schottky contacts” (Patel et al., 2017 [1]. The transparent photoelectric device was demonstrated by using various Schottky metals, such as Cu, Mo and Ni. This article mainly shows the optical transmittance of the Ni-transparent Schottky photodetector, analyzed by the energy dispersive spectroscopy and interfacial TEM images for transparency to observe the interface between NiO and TiO2 film. The observation and analyses clearly show that no pinhole formation in the TiO2 film by Ni diffusion. The rapid thermal process is an effective way to form the quality TiO2 film formation without degradation, such as pinholes (Qiu et al., 2015 [2]. This thermal process may apply to form functional metal oxide layers for solar cells and photodetectors.

  13. Biomimetic Approach to Solar Cells Based on TiO2 Nanotubes

    National Research Council Canada - National Science Library

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

    2008-01-01

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

  14. Synthesis of nanocomposite coating based on TiO2/ZnAl layer double hydroxides

    International Nuclear Information System (INIS)

    Jovanov, V.; Rudic, O.; Ranogajec, J.; Fidanchevska, E.

    2017-01-01

    The aim of this investigation was the synthesis of nanocomposite coatings based on Zn-Al layered double hydroxides (Zn-Al LDH) and TiO2. The Zn-Al LDH material, which acted as the catalyst support of the active TiO2 component (in the content of 3 and 10 wt. %), was synthesized by a low super saturation co-precipitation method. The interaction between the Zn-Al LDH and the active TiO2 component was accomplished by using vacuum evaporation prior to the mechanical activation and only by mechanical activation. The final suspension based on Zn-Al LDH and 10wt. % TiO2, impregnated only by mechanical activation, showed the optimal characteristics from the aspect of particle size distribution and XRD analysis. These properties had a positive effect on the functional properties of the coatings (photocatalytic activity and self-cleaning efficiency) after the water rinsing procedure. [es

  15. Polymer Photovoltaic Cell Using TiO2/G-PEDOT Nanocomplex Film as Electrode

    Directory of Open Access Journals (Sweden)

    F. X. Xie

    2008-01-01

    Full Text Available Using TiO2/G-PEDOT (PEDOT/PSS doped with glycerol nanocomplex film as a substitute for metal electrode in organic photovoltaic cell is described. Indium tin oxide (ITO worked as cathode and TiO2/G-PEDOT nanocomplex works as anode. The thickness of TiO2 layer in nanocomplex greatly affects the act of this nonmetallic electrode of the device. To enhance its performance, this inverted organic photovoltaic cell uses another TiO2 layer as electron selective layer contacted to ITO coated glass substrates. All films made by solution processing techniques are coated on the transparent substrate (glass with a conducting film ITO. The efficiency of this solar cell is compared with the conventional device using Al as electrode.

  16. ADSORCIÓN DE ALDEHÍDOS INSATURADOS SOBRE TiO2

    OpenAIRE

    Natalia Ortega; Oswaldo Núñez

    2012-01-01

    En el presente trabajo se estudió la adsorción de aldehídos insaturados sobre la superficie del TiO2. Para evaluar su eficiencia como catalizador, se realizaron experimentos de fotocatálisis heterogénea de p-nitrofenol (PNF) y una muestra proveniente de efluentes industriales. Se empleó un simulador solar y cuatro sistemas de TiO2: el TiO2-sólo (sin modificar) y los sistemas TiO2-dienal constituidos por la adsorción química de 2,4 hexadienal, 2,4 heptadienal y el trans-cinamaldehído sobre la ...

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

    Science.gov (United States)

    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.

  18. Control of Electron Transfer from Lead-Salt Nanocrystals to TiO 2

    KAUST Repository

    Hyun, Byung-Ryool; Bartnik, A. C.; Sun, Liangfeng; Hanrath, Tobias; Wise, F. W.

    2011-01-01

    The roles of solvent reorganization energy and electronic coupling strength on the transfer of photoexcited electrons from PbS nanocrystals to TiO 2 nanoparticles are investigated. We find that the electron transfer depends only weakly

  19. GW quasiparticle bandgaps of anatase TiO2 starting from DFT + U.

    Science.gov (United States)

    Patrick, Christopher E; Giustino, Feliciano

    2012-05-23

    We investigate the quasiparticle band structure of anatase TiO(2), a wide gap semiconductor widely employed in photovoltaics and photocatalysis. We obtain GW quasiparticle energies starting from density-functional theory (DFT) calculations including Hubbard U corrections. Using a simple iterative procedure we determine the value of the Hubbard parameter yielding a vanishing quasiparticle correction to the fundamental bandgap of anatase TiO(2). The bandgap (3.3 eV) calculated using this optimal Hubbard parameter is smaller than the value obtained by applying many-body perturbation theory to standard DFT eigenstates and eigenvalues (3.7 eV). We extend our analysis to the rutile polymorph of TiO(2) and reach similar conclusions. Our work highlights the role of the starting non-interacting Hamiltonian in the calculation of GW quasiparticle energies in TiO(2) and suggests an optimal Hubbard parameter for future calculations.

  20. Recent Progress in TiO2-Mediated Solar Photocatalysis for Industrial Wastewater Treatment

    Directory of Open Access Journals (Sweden)

    Tong Zhang

    2014-01-01

    Full Text Available The current paper reviews the application of TiO2-mediated solar photocatalysis for industrial wastewater treatment, starting with a brief introduction on the background of industrial wastewater and the development of wastewater treatment processes, especially advanced oxidation processes (AOPs. We, then, discuss the application of solar TiO2 photocatalysis in treating different kinds of industrial wastewater, such as paper mill wastewater, textile wastewater, and olive mill wastewater. In the end, we compare solar TiO2 photocatalysis with other AOPs in terms of effectiveness, energy, and chemical consumption. Personal perspectives are also given, which may provide new insights to the future development of TiO2 photocatalysis for industrial wastewater.

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

    Science.gov (United States)

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

    2008-10-01

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

  2. Three-dimensional observation of TiO2 nanostructures by electron tomography

    KAUST Repository

    Suh, Young Joon; Lu, Ning; Park, Seong Yong; Lee, Tae Hun; Lee, Sang Hoon; Cha, Dong Kyu; Lee, Min Gun; Huang, Jie; Kim, Sung Soo; Sohn, Byeong Hyeok; Kim, Geung Ho; Ko, Min Jae; Kim, Jiyoung; Kim, Moon J.

    2013-01-01

    Three-dimensional nanostructures of TiO2 related materials including nanotubes, electron acceptor materials in hybrid polymer solar cells, and working electrodes of dye sensitized solar cells (DSSCs) were visualized by electron tomography as well

  3. Novel bamboo structured TiO2 nanotubes for energy storage/production applications

    Science.gov (United States)

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

    2018-04-01

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

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

    Directory of Open Access Journals (Sweden)

    Xiaomeng Wu

    2012-01-01

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

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  6. Studies on Nano-Engineered TiO2 Photo Catalyst for Effective Degradation of Dye

    Science.gov (United States)

    Sowmya, S. R.; Madhu, G. M.; Hashir, Mohammed

    2018-02-01

    All Heterogeneous photo catalysis employing efficient photo-catalyst is the advanced dye degradation technology for the purification of textile effluent. The present work focuses on Congo red dye degradation employing synthesized Ag doped TiO2 nanoparticles as photocatalyst which is characterized using SEM, XRD and FTIR. Studies are conducted to study the effect of various parameters such as initial dye concentration, catalyst loading and pH of solution. Ag Doped TiO2 photocatalyst improve the efficacy of TiO2 by reducing high band gap and electron hole recombination of TiO2. The reaction kinetics is analyzed and the process is found to follow pseudo first order kinetics.

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

    Science.gov (United States)

    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.

  8. Variable range hopping in TiO2 insulating layers for oxide electronic devices

    Directory of Open Access Journals (Sweden)

    Y. L. Zhao

    2012-03-01

    Full Text Available TiO2 thin films are of importance in oxide electronics, e.g., Pt/TiO2/Pt for memristors and Co-TiO2/TiO2/Co-TiO2 for spin tunneling devices. When such structures are deposited at a variety of oxygen pressures, how does TiO2 behave as an insulator? We report the discovery of an anomalous resistivity minimum in a TiO2 film at low pressure (not strongly dependent on deposition temperature. Hall measurements rule out band transport and in most of the pressure range the transport is variable range hopping (VRH though below 20 K it was difficult to differentiate between Mott and Efros-Shklovskii's (ES mechanism. Magnetoresistance (MR of the sample with lowest resistivity was positive at low temperature (for VRH but negative above 10 K indicating quantum interference effects.

  9. 1 composite mixture of TiO2 nanoparticles and nanotubes in dye

    Indian Academy of Sciences (India)

    Administrator

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

  10. Production of TiO_2 particles by sol-gel ultrasound assisted for photocatalytic applications

    International Nuclear Information System (INIS)

    Martinez Rojas, Vanessa; Solis Veliz, Jose; Gomez Leon, Monica; Matejova, Lenka; Lopez, Alcides; Cruz, Gerardo J.

    2015-01-01

    Synthesis of TiO_2 particles was made by sol-gel technique assisted of ultrasonic radiation from an alcoholic solution of titanium isopropoxide. Then was subjected to a heat treatment in air at 350 °C for 1 h. X-ray diffraction and transmission electron microscopy confirmed that the size of the crystalline domains is between 10 and 37 nm. Infrared spectroscopy study confirms the presence of -OH groups on the surface of TiO_2. Modification of the morphology and surface area, due to the influence of exposure time to the ultrasonic radiation, is evidenced by studies of SEM and BET respectively. Properties of TiO_2 obtained were studied by monitoring the degradation of solutions of methyl orange in the presence of UV-A radiation. It was observed that larger the ultrasonic radiation exposure during the TiO_2 synthesis larger the constant velocity for the photocatalytic reaction for the methyl orange. (author)

  11. High-temperature interaction in the ZrSiO4-TiO2 system

    International Nuclear Information System (INIS)

    Matveeva, F.A.; Melekhova, T.F.; Samsonova, T.I.

    1976-01-01

    The solid phase interaction in the ZrSiO 4 - TiO 2 system in the region of lower concentrations of TiO 2 (between 0-30%) when heating in the range 1400-1600 0 C is investigated. The different mechanism of the interaction of zircon and titanium dioxide with a content of titanium dioxide of 10% and higher is shown. In compounds with a TiO 2 content to 10%, a solid solution of titanium dioxide and zircon arises, with a limiting value of TiO 2 dissolving in zircon of 1% at 1400 0 C and 2% at 1500-1600 0 C. The partial decomposition of zircon giving crystobalite and the solid solution of separated zirconium dioxide with rutile occurs when the content of titanium dioxide is higher than 10%

  12. TiO2 Nanoparticles as a Soft X-ray Molecular Probe

    Energy Technology Data Exchange (ETDEWEB)

    Larabell, Carolyn; Ashcroft, Jared M.; Gu, Weiwei; Zhang, Tierui; Hughes, Steven M.; Hartman, Keith B.; Hofmann, Cristina; Kanaras, Antonios G.; Kilcoyne, David A.; Le Gros, Mark; Yin, Yadong; Alivisatos, A. Paul; Larabell, Carolyn A.

    2007-06-30

    With the emergence of soft x-ray techniques for imaging cells, there is a pressing need to develop protein localization probes that can be unambiguously identified within the region of x-ray spectrum used for imaging. TiO2 nanocrystal colloids, which have a strong absorption cross-section within the "water-window" region of x-rays, areideally suited as soft x-ray microscopy probes. To demonstrate their efficacy, TiO2-streptavidin nanoconjugates were prepared and subsequently labeled microtubules polymerized from biotinylated tubulin. The microtubules were imaged using scanning transmission x-ray microscopy (STXM), and the TiO2 nanoparticle tags were specifically identified using x-ray absorption near edge spectroscopy (XANES). These experiments demonstrate that TiO2 nanoparticles are potential probes for protein localization analyses using soft x-ray microscopy.

  13. Non-equilibrium nitrogen DC-arc plasma treatment of TiO2 nanopowder.

    Science.gov (United States)

    Suzuki, Yoshikazu; Gonzalez-Aguilar, José; Traisnel, Noel; Berger, Marie-Hélène; Repoux, Monique; Fulcheri, Laurent

    2009-01-01

    Non-equilibrium nitrogen DC-arc plasma treatment of a commercial TiO2 anatase nanopowder was examined to obtain nitrogen-doped TiO2. By using a non-thermal discharge at low current (150 mA) and high voltage (1200 V) using pure N2 gas, light yellowish-gray TiO2 powder was successfully obtained within a short period of 5-10 min. XPS and TEM-EELS studies confirmed the existence of doped nitrogen. Due to the relatively mild conditions (plasma power of 180 W), metastable anatase structure and fine crystallite size of TiO2 (ca. 10 nm) were maintained after the plasma treatment. The in-flight powder treatment system used in this study is promising for various type of powder treatment.

  14. One-step preparation and photocatalytic performance of vanadium doped TiO2 coatings

    International Nuclear Information System (INIS)

    Vasilić, R.; Stojadinović, S.; Radić, N.; Stefanov, P.; Dohčević-Mitrović, Z.; Grbić, B.

    2015-01-01

    In this paper, we have investigated one-step preparation of vanadium doped TiO 2 coatings formed by plasma electrolytic oxidation (PEO) of titanium in electrolyte containing 10 g/L Na 3 PO 4 ·12H 2 O + 0.5 g/L NH 4 VO 3 . The morphology, phase structure, and elemental composition of the formed coatings were characterized by atomic force microscopy (AFM), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) techniques. Ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS) was employed to evaluate the band gap energy of obtained coatings. Vanadium doped TiO 2 coatings are partly crystallized and mainly composed of anatase phase TiO 2 , with up to about 2 wt% of vanadium present in the surface layer of the oxide. The valence band photoelectron spectra and UV–Vis DRS showed that vanadium doped TiO 2 coatings exhibit notable red shift with respect to the pure TiO 2 coatings. The photocatalytic activity was evaluated by monitoring the degradation of methyl orange under simulated sunlight conditions. Photocatalytic activity of vanadium doped TiO 2 coatings increases with PEO time. Prolonged PEO times result in higher roughness of obtained coatings, thus increasing surface area available for methyl orange degradation. Vanadium doped TiO 2 coatings obtained after 180 s of PEO time exhibit the best photocatalytic activity and about 67% of methyl orange is degraded after 12 h of irradiation under simulated sunlight. - Highlights: • One-step preparation of V-doped TiO 2 coatings in 10 g/L Na 3 PO 4 ·12H 2 O + 0.5 g/L NH 4 VO 3 . • Properties of obtained coatings strongly depend on microdischarge characteristics. • Band gap of V-doped TiO 2 coatings is shifted towards red side of the spectrum. • V-doped TiO 2 coatings have better photocatalytic activity than pure TiO 2 . • After 12 h of simulated sunlight irradiation, 67% of methyl orange was decomposed

  15. An enzymatic glucose biosensor based on a glassy carbon electrode modified with cylinder-shaped titanium dioxide nanorods

    International Nuclear Information System (INIS)

    Yang, Zhanjun; Xu, Youbao; Li, Juan; Jian, Zhiqin; Yu, Suhua; Zhang, Yongcai; Hu, Xiaoya; Dionysiou, Dionysios D.

    2015-01-01

    We describe a highly sensitive electrochemical enzymatic glucose biosensor. A glassy carbon electrode was modified with cylinder-shaped titanium dioxide nanorods (TiO 2 -NRs) for the immobilization of glucose oxidase. The modified nanorods and the enzyme biosensor were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, electrochemical impedance spectroscopy and cyclic voltammetry. The glucose oxidase on the TiO 2 -NRs displays a high activity and undergoes fast surface-controlled electron transfer. A pair of well-defined quasi-reversible redox peaks was observed at −0.394 and −0.450 V. The TiO 2 -NRs provide a good microenvironment to facilitate the direct electron transfer between enzyme and electrode surface. The biosensor has two linear response ranges, viz. from 2.0 to 52 μM, and 0.052 to 2.3 mM. The lower detection limit is 0.5 μM, and the sensitivity is 68.58 mA M −1 cm −2 . The glucose biosensor is selective, well reproducible, and stable. In our perception, the cylindrically shaped TiO 2 -NRs provide a promising support for the immobilization of proteins and pave the way to the development of high-performance biosensors. (author)

  16. Highly efficient perovskite solar cells based on a nanostructured WO3-TiO2 core-shell electron transporting material

    KAUST Repository

    Mahmood, Khalid; Swain, Bhabani Sankar; Kirmani, Ahmad R.; Amassian, Aram

    2015-01-01

    Until recently, only mesoporous TiO2 and ZnO were successfully demonstrated as electron transport layers (ETL) alongside the reports of ZrO2 and Al2O3 as scaffold materials in organometal halide perovskite solar cells, largely owing to ease of processing and to high power conversion efficiency. In this article, we explore tungsten trioxide (WO3)-based nanostructured and porous ETL materials directly grown hydrothermally with different morphologies such as nanoparticles, nanorods and nanosheet arrays. The nanostructure morphology strongly influences the photocurrent and efficiency in organometal halide perovskite solar cells. We find that the perovskite solar cells based on WO3 nanosheet arrays yield significantly enhanced photovoltaic performance as compared to nanoparticles and nanorod arrays due to good perovskite absorber infiltration in the porous scaffold and more rapid carrier transport. We further demonstrate that treating the WO3 nanostructures with an aqueous solution of TiCl4 reduces charge recombination at the perovskite/WO3 interface, resulting in the highest power conversion efficiency of 11.24% for devices based on WO3 nanosheet arrays. The successful demonstration of alternative ETL materials and nanostructures based on WO3 will open up new opportunities in the development of highly efficient perovskite solar cells. This journal is © The Royal Society of Chemistry 2015.

  17. Karakteristik Pasta TiO2 Suhu Rendah untuk Aplikasi Dye Sensitized Solar Cell (DSSC

    Directory of Open Access Journals (Sweden)

    Mariya Al Qibtiya

    2016-06-01

    Full Text Available Pada tulisan ini, diuraikan karakteristik pasta TiO2 suhu rendah untuk aplikasi sel surya berbasis dye-sensitized yang dipreparasi dengan penambahan serbuk TiO2 reflektor. Penambahan TiO2 reflektor sebagai light scattering layer pada pasta dilakukan untuk melihat pengaruhnya terhadap karakteristik listrik sel surya yang dihasilkan. Preparasi pasta dilakukan menggunakan bahan komersial yaitu pasta T-Nanooxide D-L (Solaronix dan serbuk pasta WER2-O (Dyesiol sebagai bahan reflector. Bahan tersebut dianalisis struktur kristalnya. Hasil karakterisasi X-Ray Diffraction (XRD menunjukan bahwa bahan TiO2 serbuk yang digunakan adalah nanokristal dengan struktur kristal anatase. Pasta ini dideposisi di atas permukaan plastik dan kaca konduktif (ITO-PET dan FTO dengan metode doctor blade printing. Proses sintering lapisan TiO2 dilakukan pada suhu rendah yaitu 120 ˚C selama 4 jam. Morfologi permukaan lapisan TiO2 dianalisa menggunakan Scanning Electron Microscopy (SEM. Lapisan TiO2 yang terbentuk diaplikasikan pada DSSC sebagai fotoelektroda. Pewarnaan dengan larutan N-719 (Ruthenium Complex, lapisan elektroda kerja platina dan larutan elektrolit iodine. Karakteristik kurva I-V dengan ukuran sel daerah aktif 1 cm2 diukur menggunakan Sun Simulator AM1,5 dengan sumber cahaya Xenon dan intensitas 50 mW/cm2. Hasil pengukuran menunjukkan penambahan serbuk TiO2 reflektor dapat meningkatkan unjuk kerja sel surya fleksibel yang dihasilkan. Efisiensi terbaik DSSC yang dihasilkan adalah 0,166% untuk substrat plastik dan 0,167% untuk substrat kaca.

  18. TiO2-Based Nanomaterials for Gas Sensing-Influence of Anatase and Rutile Contributions.

    Science.gov (United States)

    Zakrzewska, K; Radecka, M

    2017-12-01

    The paper deals with application of three nanomaterial systems: undoped TiO 2 , chromium-doped TiO 2 :Cr and TiO 2 -SnO 2 synthesized by flame spray synthesis (FSS) technique for hydrogen sensing. The emphasis is put on the role of anatase and rutile polymorphic forms of TiO 2 in enhancing sensitivity towards reducing gases. Anatase-to-rutile transformation is achieved by annealing of undoped TiO 2 in air at 700 °C, specific Cr doping and modification with SnO 2 . Undoped TiO 2 and TiO 2 -SnO 2 exhibit n-type behaviour and while TiO 2 : 5 at.% Cr is a p-type semiconductor. X-ray diffraction (XRD) has been applied to determine anatase-to-rutile weight ratio as well as anatase and rutile crystal size. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have been used to characterize the structure and morphological parameters. Optical reflectometry enabled to find and compare the band gaps E g of anatase and rutile predominated compositions. Electrical properties, i.e. the electrical conductivity and values of constant phase element (CPE), have been established on the basis of impedance spectroscopy. Dynamic responses of the electrical resistance as a function of hydrogen concentration revealed that predominance of rutile in anatase/rutile mixture is beneficial for gas sensing. Partial transformation to rutile in all three material systems under study resulted in an increased sensitivity towards hydrogen. It is proposed that this effect can be explained in a similar way as in photocatalysis, i.e. by specific band alignment and electron transfer from rutile to anatase to facilitate oxygen preadsorption on the surface of anatase grains.

  19. Genotoxic and cytotoxic activity of green synthesized TiO2 nanoparticles

    Science.gov (United States)

    Koca, Fatih Doğan; Duman, Fatih

    2018-03-01

    Nowadays, nanomaterials that are smaller than 100 nm in size are very attractive owing to their enhanced physicochemical properties. Although they have been used widely for industrial applications, their toxicity still remains a problem. This article is a new record of the synthesis of titanium dioxide nanoparticles (TiO2 NPs) by a Mentha aquatica leaf extract and determination of its toxicity to rat marrow mesenchymal stem cells. In this study, we aimed to determine the genotoxic and cytotoxic effects of biologically synthetized TiO2 NPs. The characteristic peak of the nanomaterial was observed at 354 nm. The mean size of the nanomaterial was measured to be 69 nm from SEM images. According to zeta analysis, the surface charge of the nanomaterial was - 37.6 mV. The crystalline structure of the nanomaterial was determined using XRD analysis. It was concluded that the obtained nanomaterial was TiO2 The results of the FT-IR analysis showed that the functional groups that were found in the plant extract could play an important role in the formation and stabilization of TiO2 NPs. The effective size of the TiO2 NPs was found to be 304 nm using DLS analysis. The TGA analysis results showed that the total mass loss was 4% at 900 °C. According to DNA cleavage analysis results, TiO2 NPs cause damage to the plasmid pBR322 DNA in a concentration-dependant matter. It has been noted that TiO2 NPs lead to decreased cell viability during increased time and concentration of applications on rat marrow mesenchymal stem cells. It has also been determined that bulk TiO2 causes a greater reduction in the stem cell viability compared to the biosynthesized NPs. The obtained results could be useful for further application and toxicity studies.

  20. CdS-sensitized TiO2 nanocorals: hydrothermal synthesis, characterization, application.

    Science.gov (United States)

    Mali, S S; Desai, S K; Dalavi, D S; Betty, C A; Bhosale, P N; Patil, P S

    2011-10-01

    Cadmium sulfide (CdS) nanoparticle-sensitized titanium oxide nanocorals (TNC) were synthesized using a two-step deposition process. The TiO(2) nanocorals were grown on the conducting glass substrates (FTO) using A hydrothermal process and CdS nanoparticles were loaded on TNC using successive ionic layer adsorption and reaction (SILAR) method. The TiO(2), CdS and TiO(2)-CdS samples were characterized by optical absorption, X-ray diffraction (XRD), FT-Raman, FT-IR, scanning electron microscopy (SEM) and contact angle. Further, their photoelectrochemical (PEC) performance was tested in NaOH, Na(2)S-NaOH-S and Na(2)S electrolytes, respectively. When CdS nanoparticles are coated on TNCs, the optical absorption is found to be enhanced and band edge is red-shifted towards visible region. The TiO(2)-CdS sample exhibits improved photoelectrochemical (PEC) performance with maximum short circuit current of (J(sc)) 1.04 mA cm(-2). After applying these TiO(2)-CdS electrodes in photovoltaic cells, the photocurrent was found to be enhanced by 2.7 and 32.5 times, as compared with those of bare CdS and TiO(2) nanocorals films electrodes respectively. Also, the power conversion efficiency of TiO(2)-CdS electrodes is 0.72%, which is enhanced by about 16 and 29 times for TiO(2), CdS samples. This journal is © The Royal Society of Chemistry and Owner Societies 2011

  1. Deep-level transient spectroscopy of TiO2/CuInS2 heterojunctions

    NARCIS (Netherlands)

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

    2005-01-01

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

  2. Catalytic Study on TiO2 Photo catalyst Synthesised Via Microemulsion Method on Atrazine

    International Nuclear Information System (INIS)

    Ruslimie, C.A.; Hasmizam Razali; Khairul, W.M.

    2011-01-01

    Titanium dioxide photo catalyst was synthesised by microemulsions method under controlled hydrolysis of titanium butoxide, Ti(O(CH 2 ) 3 )CH 3 . The synthesised TiO 2 photo catalyst was compared with Sigma-commercial TiO 2 by carrying out the investigation on its properties using scanning electron microscopy (SEM), x-ray diffraction (XRD) analysis and thermal gravimetric analysis (TGA). The photo catalytic activities for both photo catalysts were studied for atrazine photodegradation. (author)

  3. Physicochemical Study of Photocatalytic Activity of TiO2 Supported Palygorskite Clay Mineral

    Directory of Open Access Journals (Sweden)

    Lahcen Bouna

    2013-01-01

    Full Text Available This study deals with the influence of physicochemical parameters, namely, the photocatalyst loading, dye concentration, and pH of polluted solutions, on the degradation efficiency of Orange G (OG solutions containing TiO2 nanoparticles supported on palygorskite clay mineral (TiO2-Pal. The TiO2 photocatalyst attached to natural palygorskite fibers was elaborated by colloidal sol-gel route. It exhibits the anatase structure that is the most photoactive crystallographic form. The highest performances of supported photocatalyst on OG degradation were found using an optimum amount of TiO2-Pal around 0.8 g·L−1, which corresponds properly to ca. 0.4 g·L−1 of TiO2. This amount is interestingly lower than the 2.5 g·L−1 generally reported when using pure unsupported TiO2 powder. The photodegradation rate increases by decreasing OG initial concentration, and it was found significantly higher when the OG solution is either acidic (pH<4 or basic (pH≈11. For OG concentrations in the range 5×10-6– 5×10-4 M, the kinetic law of the OG degradation in presence of TiO2-Pal is similar to that reported for unsupported TiO2 nanopowder. It follows a Langmuir-Hinshelwood model with a first-order reaction and an apparent rate constant of about 2.9×10-2 min−1.

  4. TiO2 nanoparticles in seawater: Aggregation and interactions with the green alga Dunaliella tertiolecta.

    Science.gov (United States)

    Morelli, Elisabetta; Gabellieri, Edi; Bonomini, Alessandra; Tognotti, Danika; Grassi, Giacomo; Corsi, Ilaria

    2018-02-01

    Titanium dioxide nanoparticles (TiO 2 NPs) have been widely employed in industrial applications, thus rising concern about their impact in the aquatic environment. In this study we investigated the chemical behaviour of TiO 2 NPs in the culture medium and its effect on the green alga Dunaliella tertiolecta, in terms of growth inhibition, oxidative stress, ROS (Reactive Oxygen Species) accumulation and chlorophyll content. In addition, the influence of exopolymeric substances (EPS) excreted by the microalgae on the stability of NPs has been evaluated. The physicochemical characterization showed a high propensity of TiO 2 NPs to form micrometric-sized aggregates within 30min, large enough to partially settle to the bottom of the test vessel. Indeed, an increasing amount of TiO 2 particles settled out with time, but the presence of EPS seemed to mitigate this behaviour in the first 6h of exposure where the main effects in D. tertiolecta were observed. TiO 2 NPs did not inhibit the 72-h growth rate of D. tertiolecta, nor affected the cellular chlorophyll concentration in the range 0.01-10mgL -1 . The time-course of ROS production showed an initial transient increase of ROS in TiO 2 NP-exposed algae compared to the control, concomitant with an enhancement of catalase activity. Interestingly, intracellular ROS was a small fraction of total ROS, the highest amount being extracellular. The occurrence of cell-mediated chemical transformations of TiO 2 NPs in the external medium, related to the presence of EPS, has been evaluated. Our results showed that carbohydrates were the major component of EPS, whereas proteins of medium molecular weight (20-80kDa) were preferentially bound to TiO 2 NPs, likely influencing their biological fate. Copyright © 2017 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

    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. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Microglial cells (BV-2) internalize titanium dioxide (TiO2) nanoparticles: toxicity and cellular responses.

    Science.gov (United States)

    Rihane, Naima; Nury, Thomas; M'rad, Imen; El Mir, Lassaad; Sakly, Mohsen; Amara, Salem; Lizard, Gérard

    2016-05-01

    Because of their whitening and photocatalytic effects, titanium dioxide nanoparticles (TiO2-NPs) are widely used in daily life. These NPs can be found in paints, plastics, papers, sunscreens, foods, medicines (pills), toothpastes, and cosmetics. However, the biological effect of TiO2-NPs on the human body, especially on the central nervous system, is still unclear. Many studies have demonstrated that the brain is one of the target organs in acute or chronic TiO2-NPs toxicity. The present study aimed to investigate the effect of TiO2-NPs at different concentrations (0.1 to 200 μg/mL) on murine microglial cells (BV-2) to assess their activity on cell growth and viability, as well as their neurotoxicity. Different parameters were measured: cell viability, cell proliferation and DNA content (SubG1 peak), mitochondrial depolarization, overproduction of reactive oxygen species (especially superoxide anions), and ultrastructural changes. Results showed that TiO2-NPs induced some cytotoxic effects with a slight inhibition of cell growth. Thus, at high concentrations, TiO2-NPs were not only able to inhibit cell adhesion but also enhanced cytoplasmic membrane permeability to propidium iodide associated with a loss of mitochondrial transmembrane potential and an overproduction of superoxide anions. No induction of apoptosis based on the presence of a SubG1 peak was detected. The microscopic observations also indicated that small groups of nanosized particles and micron-sized aggregates were engulfed by the BV-2 cells and sequestered as intracytoplasmic aggregates after 24-h exposure to TiO2-NPs. Altogether, our data show that the accumulation TiO2-NPs in microglial BV-2 cells favors mitochondrial dysfunctions and oxidative stress.

  7. Effects of Homogenization Scheme of TiO2 Screen-Printing Paste for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Seigo Ito

    2012-01-01

    Full Text Available TiO2 porous electrodes have been fabricated for photoelectrodes in dye-sensitized solar cells (DSCs using TiO2 screen-printing paste from nanocrystalline TiO2 powder dried from the synthesized sol. We prepared the TiO2 screen-printing paste by two different methods to disperse the nanocrystalline TiO2 powder: a “ball-milling route” and a “mortal-grinding route.” The TiO2 ball-milling (TiO2-BM route gave monodisperse TiO2 nanoparticles, resulting in high photocurrent density (14.2 mA cm−2 and high photoconversion efficiency (8.27%. On the other hand, the TiO2 mortal-grinding (TiO2-MG route gave large aggregate of TiO2 nanoparticles, resulting in low photocurrent density (11.5 mA cm−2 and low photoconversion efficiency (6.43%. To analyze the photovoltaic characteristics, we measured the incident photon-to-current efficiency, light absorption spectroscopy, and electrical impedance spectroscopy of DSCs.

  8. Wet-Chemical Preparation of TiO2-Based Composites with Different Morphologies and Photocatalytic Properties

    Directory of Open Access Journals (Sweden)

    Liqin Xiang

    2017-10-01

    Full Text Available TiO2-based composites have been paid significant attention in the photocatalysis field. The size, crystallinity and nanomorphology of TiO2 materials have an important effect on the photocatalytic efficiency. The synthesis and photocatalytic activity of TiO2-based materials have been widely investigated in past decades. Based on our group’s research works on TiO2 materials, this review introduces several methods for the fabrication of TiO2, rare-earth-doped TiO2 and noble-metal-decorated TiO2 particles with different morphologies. We focused on the preparation and the formation mechanism of TiO2-based materials with unique structures including spheres, hollow spheres, porous spheres, hollow porous spheres and urchin-like spheres. The photocatalytical activity of urchin-like TiO2, noble metal nanoparticle-decorated 3D (three-dimensional urchin-like TiO2 and bimetallic core/shell nanoparticle-decorated urchin-like hierarchical TiO2 are briefly discussed.

  9. Effect of dissolved ozone or ferric ions on photodegradation of thiacloprid in presence of different TiO2 catalysts

    International Nuclear Information System (INIS)

    Cernigoj, Urh; Stangar, Urska Lavrencic; Jirkovsky, Jaromir

    2010-01-01

    Combining TiO 2 photocatalysis with inorganic oxidants (such as O 3 and H 2 O 2 ) or transition metal ions (Fe 3+ , Cu 2+ and Ag + ) often leads to a synergic effect. Electron transfer between TiO 2 and the oxidant is usually involved. Accordingly, the degree of synergy could be influenced by TiO 2 surface area. With this in mind, the disappearance of thiacloprid, a neonicotinoid insecticide, was studied applying various photochemical AOPs and different TiO 2 photocatalysts. In photocatalytic ozonation experiments, synergic effect of three different TiO 2 photocatalysts was quantified. Higher surface area resulted in a more pronounced synergic effect but an increasing amount of TiO 2 did not influence the degree of the synergy. This supports the theory that the synergy is a consequence of adsorption of ozone on the TiO 2 surface. No synergy was observed in photocatalytic degradation of thiacloprid in the presence of dissolved iron(III) species performed under varied experimental conditions (concentration, age of iron(III) solution, different TiO 2 films, usage of TiO 2 slurries). This goes against the literature for different organic compounds (i.e., monuron). It indicates different roles of iron(III) in the photodegradation of different organic molecules. Moreover, TiO 2 surface area did not affect photodegradation efficiency in iron(III)-based experiments which could confirm absence of electron transfer between TiO 2 photocatalyst and iron(III).

  10. The Photocatalytic Activity and Compact Layer Characteristics of TiO2 Films Prepared Using Radio Frequency Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    H. C. Chang

    2014-01-01

    Full Text Available TiO2 compact layers are used in dye-sensitized solar cells (DSSCs to prevent charge recombination between the electrolyte and the transparent conductive substrate (indium tin oxide, ITO; fluorine-doped tin oxide, FTO. Thin TiO2 compact layers are deposited onto ITO/glass by means of radio frequency (rf magnetron sputtering, using deposition parameters that ensure greater photocatalytic activity and increased DSSC conversion efficiency. The photoinduced decomposition of methylene blue (MB and the photoinduced hydrophilicity of the TiO2 thin films are also investigated. The photocatalytic performance characteristics for the deposition of TiO2 films are improved by using the Grey-Taguchi method. The average transmittance in the visible region exceeds 85% for all samples. The XRD patterns of the TiO2 films, for sol-gel with spin coating of porous TiO2/TiO2 compact/ITO/glass, show a good crystalline structure. In contrast, without the TiO2 compact layer (only porous TiO2, the peak intensity of the anatase (101 plane in the XRD patterns for the TiO2 film has a lower value, which demonstrates inferior crystalline quality. With a TiO2 compact layer to prevent charge recombination, a higher short-circuit current density is obtained. The DSSC with the FTO/glass and Pt counter electrode demonstrates the energy conversion efficiency increased.

  11. Photocatalytic Study of New Immobilized TiO2 Technique Towards Degradation of Reactive Red 4 Dye

    Directory of Open Access Journals (Sweden)

    Ain S. K.

    2016-01-01

    Full Text Available The study on TiO2 for wastewater remediation has gained interest among researchers. However, the application of this photocatalyst is limited due to non-recyclability of conventional TiO2. Thus, immobilization technique has been developed to solve this issue. Hence, a comparison study between two types of immobilized photocatalysts namely titanium dioxide (TiO2 and TiO2 mixed with polyvinyl alcohol (PVA has been conducted in this work to observe the significant effect of PVA polymer in photocatalysis reaction of reactive red 4 (RR4 dye. Double sided adhesive tape (DSAT was used as thin layer binder in this immobilization system. The result shows that the photocatalytic performance of TiO2-PVA/DSAT was higher than that of TiO2/DSAT under both normal UV and visible light irradiations due to the conjugated unsaturated polymer from PVA serve as electron donor for TiO2 thus increase the photocatalysis process. Besides, TiO2-PVA/DSAT was also found to possess much better adhesion strength to the support material compared to TiO2/DSAT. Based on the findings, this TiO2 immobilization system is expected to be beneficial in the industrial wastewater treatment. Thus, further study to improve the photocatalytic activity of this immobilized TiO2 will be in our future work.

  12. Degradation of organic dyes using spray deposited nanocrystalline stratified WO3/TiO2 photoelectrodes under sunlight illumination

    Science.gov (United States)

    Hunge, Y. M.; Yadav, A. A.; Mahadik, M. A.; Bulakhe, R. N.; Shim, J. J.; Mathe, V. L.; Bhosale, C. H.

    2018-02-01

    The need to utilize TiO2 based metal oxide hetero nanostructures for the degradation of environmental pollutants like Rhodamine B and reactive red 152 from the wastewater using stratified WO3/TiO2 catalyst under sunlight illumination. WO3, TiO2 and stratified WO3/TiO2 catalysts were prepared by a spray pyrolysis method. It was found that the stratified WO3/TiO2 heterostructure has high crystallinity, no mixed phase formation occurs, strong optical absorption in the visible region of the solar spectrum, and large surface area. The photocatalytic activity was tested for degradation of Rhodamine B (Rh B) and reactive red 152 in an aqueous medium. TiO2 layer in stratified WO3/TiO2 catalyst helps to extend its absorption spectrum in the solar light region. Rh B and Reactive red 152is eliminated up to 98 and 94% within the 30 and 40 min respectively at optimum experimental condition by stratified WO3/TiO2. Moreover, stratified WO3/TiO2 photoelectrode has good stability and reusability than individual TiO2 and WO3 thin film in the degradation of Rh B and reactive red 152. The photoelectrocatalytic experimental results indicate that stratified WO3/TiO2 photoelectrode is a promising material for dye removal.

  13. TiO2 thin-films on polymer substrates and their photocatalytic activity

    International Nuclear Information System (INIS)

    Yang, Jae-Hun; Han, Yang-Su; Choy, Jin-Ho

    2006-01-01

    We have developed dip-coating process for TiO 2 -thin film on polymer substrates (acrylonitrile-butadiene-styrene polymer: ABS, polystyrene: PS). At first, a monodispersed and transparent TiO 2 nano-sol solution was prepared by the controlled hydrolysis of titanium iso-propoxide in the presence of acetylacetone and nitric acid catalyst at 80 deg. C. Powder X-ray diffraction patterns of the dried particles are indicative of crystalline TiO 2 with anatase-type structure. According to the XRD and transmission electron microscopy (TEM) studies, the mean particle size was estimated to be ca. 5 nm. The transparent thin films on ABS and PS substrates were fabricated by dip-coating process by changing the processing variables, such as the number of dip-coating and TiO 2 concentration in nano-sol solution. Scanning electron microscopic (SEM) analysis for the thin film samples reveals that the acetylacetone-modified TiO 2 nano-sol particles are effective for enhancing the interfacial adherence between films and polymeric substrates compared to the unmodified one. Photocatalytic degradation of methylene blue (MB) on the TiO 2 thin-films has also been systematically investigated

  14. Photoetching of Immobilized TiO2-ENR50-PVC Composite for Improved Photocatalytic Activity

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    M. A. Nawi

    2012-01-01

    Full Text Available Commercially acquired TiO2 photocatalyst (99% anatase powder was mixed with epoxidized natural rubber-50 (ENR50/polyvinyl chloride (PVC blend by ultrasonication and immobilized onto glass plates as TiO2-ENR50-PVC composite via a dip-coating method. Photoetching of the immobilized TiO2-ENR50-PVC composite was investigated under the irradiation of a 45 W compact fluorescent lamp and characterized by chemical oxygen demand (COD analysis, scanning electron microscopy-energy dispersive X-ray (SEM-EDX spectrometry, thermogravimetry analysis (TGA, and fourier transform infrared (FTIR spectroscopy. The BET surface area of the photoetched TiO2 composite was observed to be larger than the original TiO2 powder due to the systematic removal of ENR50 while PVC was retained within the composite. It also exhibited better photocatalytic efficiency than the TiO2 powder in a slurry mode and was highly reproducible and reusable. More than 98% of MB removal was consistently achieved for 10 repeated runs of the photo-etched photocatalyst system. About 93% of the 20 mg L−1 MB was mineralized over a period of 480 min. The presence of SO42−, NO3−, and Cl− anions was detected in the mineralized solution where the solution pH was reduced from 7 to 4.

  15. The Effects of Doping Copper and Mesoporous Structure on Photocatalytic Properties of TiO2

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    Yang Wang

    2014-01-01

    Full Text Available This paper describes a system for the synthesis of Cu-doped mesoporous TiO2 nanoparticles by a hydrothermal method at relatively low temperatures. The technique used is to dope the as-prepared mesoporous TiO2 system with copper. In this method, the copper species with the form of Cu1+, which was attributed to the reduction effect of dehydroxylation and evidenced by X-ray photoelectron spectroscopy (XPS and X-ray diffraction (XRD, was well dispersed in the optimal concentration 1 wt.% Cu-doped mesoporous TiO2. In this as-prepared mesoporous TiO2 system, original particles with a size of approximately 20 nm are aggregated together to shapes of approximately 1100 nm, which resulted in the porous aggregate structure. More importantly, the enhancement of the photocatalytic activity was discussed as effects due to the formation of stable Cu(I and the mesoporous structure in the Cu-doped mesoporous TiO2. Among them, Cu-doped mesoporous TiO2 shows the highest degradation rate of methyl orange (MO. In addition, the effects of initial solution pH on degradation of MO had also been investigated. As a result, the optimum values of initial solution pH were found to be 3.

  16. Effect of Graphite Doped TiO_2 Nanoparticles on Smoke Degradation

    International Nuclear Information System (INIS)

    Roshasnorlyza Hazan; Mohamad Shahrizal Md Zain; Natrah Syafiqah Rosli

    2016-01-01

    Secondhand smoke affects in the same way as regular smoker. The best solution is to purify the air efficiently and effectively. In this study, we were successfully doped TiO_2 nanoparticle with graphite to accelerate the degradation of cigarette smoke. The graphite doped and undoped TiO_2 nanoparticles were prepared from synthetic rutile using alkaline fusion method and their photo catalytic activity were investigated under visible light irradiation. The photo catalytic activity of the TiO_2 nanoparticles was analyzed in terms of their particle size analysis, crystallization and optical band gap. TiO_2 nanoparticle act as photo catalyzer by utilization of light energy to excite electron-hole pairs in smoke degradation processes. With the aided from graphite in TiO_2 nanoparticles, the smoke degradation was accelerate up to 44.4 %. In this case, graphite helps to reduce optical band gap of TiO_2 nanoparticle, thus increasing excitation of electron from valence band to conduction band. (author)

  17. Enhanced oxidation of naphthalene using plasma activation of TiO2/diatomite catalyst.

    Science.gov (United States)

    Wu, Zuliang; Zhu, Zhoubin; Hao, Xiaodong; Zhou, Weili; Han, Jingyi; Tang, Xiujuan; Yao, Shuiliang; Zhang, Xuming

    2018-04-05

    Non-thermal plasma technology has great potential in reducing polycyclic aromatic hydrocarbons (PAHs) emission. But in plasma-alone process, various undesired by-products are produced, which causes secondary pollutions. Here, a dielectric barrier discharge (DBD) reactor has been developed for the oxidation of naphthalene over a TiO 2 /diatomite catalyst at low temperature. In comparison to plasma-alone process, the combination of plasma and TiO 2 /diatomite catalyst significantly enhanced naphthalene conversion (up to 40%) and CO x selectivity (up to 92%), and substantially reduced the formation of aerosol (up to 90%) and secondary volatile organic compounds (up to near 100%). The mechanistic study suggested that the presence of the TiO 2 /diatomite catalyst intensified the electron energy in the DBD. Meantime, the energized electrons generated in the discharge activated TiO 2 , while the presence of ozone enhanced the activity of the TiO 2 /diatomite catalyst. This plasma-catalyst interaction led to the synergetic effect resulting from the combination of plasma and TiO 2 /diatomite catalyst, consequently enhanced the oxidation of naphthalene. Importantly, we have demonstrated the effectiveness of plasma to activate the photocatalyst for the deep oxidation of PAH without external heating, which is potentially valuable in the development of cost-effective gas cleaning process for the removal of PAHs in vehicle applications during cold start conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Enhancement of tributyltin degradation under natural light by N-doped TiO2 photocatalyst

    International Nuclear Information System (INIS)

    Bangkedphol, S.; Keenan, H.E.; Davidson, C.M.; Sakultantimetha, A.; Sirisaksoontorn, W.; Songsasen, A.

    2010-01-01

    Photo-degradation of tributyltin (TBT) has been enhanced by TiO 2 nanoparticles doped with nitrogen (N-doped TiO 2 ). The N-doped catalyst was prepared by a sol-gel reaction of titanium (IV) tetraisopropoxide with 25% ammonia solution and calcined at various temperatures from 300 to 600 deg. C. X-ray diffraction results showed that N-doped TiO 2 remained amorphous at 300 deg. C. At 400 deg. C the anatase phase occurred then transformed to the rutile phase at 600 deg. C. The crystallite size calculated from Scherrer's equation was in the range of 16-51 nm which depended on the calcination temperature. N-doped TiO 2 calcined at 400 deg. C which contained 0.054% nitrogen, demonstrated the highest photocatalytic degradation of TBT at 28% in 3 h under natural light when compared with undoped TiO 2 and commercial photocatalyst, P25-TiO 2 which gave 14.8 and 18% conversion, respectively.

  19. Surface Plasmon Enhanced Photocatalysis of Au/Pt-decorated TiO2 Nanopillar Arrays

    Science.gov (United States)

    Shuang, Shuang; Lv, Ruitao; Xie, Zheng; Zhang, Zhengjun

    2016-05-01

    The low quantum yields and lack of visible light utilization hinder the practical application of TiO2 in high-performance photocatalysis. Herein, we present a design of TiO2 nanopillar arrays (NPAs) decorated with both Au and Pt nanoparticles (NPs) directly synthesized through successive ion layer adsorption and reaction (SILAR) at room temperature. Au/Pt NPs with sizes of ~4 nm are well-dispersed on the TiO2 NPAs as evidenced by electron microscopic analyses. The present design of Au/Pt co-decoration on the TiO2 NPAs shows much higher visible and ultraviolet (UV) light absorption response, which leads to remarkably enhanced photocatalytic activities on both the dye degradation and photoelectrochemical (PEC) performance. Its photocatalytic reaction efficiency is 21 and 13 times higher than that of pure TiO2 sample under UV-vis and visible light, respectively. This great enhancement can be attributed to the synergy of electron-sink function of Pt and surface plasmon resonance (SPR) of Au NPs, which significantly improves charge separation of photoexcited TiO2. Our studies demonstrate that through rational design of composite nanostructures one can harvest visible light through the SPR effect to enhance the photocatalytic activities initiated by UV-light, and thus realize more effectively utilization of the whole solar spectrum for energy conversion.

  20. Charge transfer in photorechargeable composite films of TiO2 and polyaniline

    Science.gov (United States)

    Nomiyama, Teruaki; Sasabe, Kenichi; Sakamoto, Kenta; Horie, Yuji

    2015-07-01

    A photorechargeable battery (PRB) is a photovoltaic device having an energy storage function in a single cell. The photoactive electrode of PRB is a bilayer film consisting of bare porous TiO2 and a TiO2-polyaniline (PANi) mixture that work as a photovoltaic current generator and an electrochemical energy storage by ion dedoping, respectively. To study the charge transfer between TiO2 and PANi, the photorechargeable quantum efficiency QE ([electron count on discharge]/[incident photon count on photocharge]) was measured by varying the thickness LS of the TiO2-PANi mixture. The quantum efficiency QEuv for UV photons had a maximum of ˜7% at LS ˜ 7 µm. The time constant τTP for the charge transfer was about 10-1 s, which was longer ten times or more than the lifetime of excited electrons within TiO2. These facts reveal that the main rate-limiting factor in the photocharging process is the charge transfer between TiO2 and PANi.

  1. Photocatalytic Degradation of Methylene Blue Using TiO2 Impregnated Diatomite

    Directory of Open Access Journals (Sweden)

    Ranfang Zuo

    2014-01-01

    Full Text Available Nano-TiO2 showed a good catalytic activity, but it is easy to agglomerate, resulting in the reduction or even complete loss of photocatalytic activity. The dispersion of TiO2 particles on porous materials was a potential solution to this problem. Diatomite has high specific surface and absorbability because of its particular shell structure. Thus, TiO2/diatomite composite, prepared by loading TiO2 on the surface of diatomite, was a good photocatalyst, through absorbing organic compounds with diatomite and degrading them with TiO2. Scanning electron microscopy (SEM, energy dispersive spectrum (EDS, X-ray diffraction (XRD, chemical analysis, and Fourier transform infrared spectrometry (FTIR indicated that TiO2 was impregnated well on the surface of diatomite. Furthermore, TiO2/diatomite was more active than nano-TiO2 for the degradation of methylene blue (MB in solution. MB at concentrations of 15 and 35 ppm can be completely degraded in 20 and 40 min, respectively.

  2. Photocatalytic decolorization of basic dye by TiO2 nanoparticle in photoreactor

    Directory of Open Access Journals (Sweden)

    Jutaporn Chanathaworn1

    2012-04-01

    Full Text Available Photocatalytic decolorization of rhodamine B (RB and malachite green (MG basic dyes in aqueous solution wasevaluated using TiO2 powder as a semiconductor photocatalyst under UV black light irradiation. A 0.5 L batch photoreactorcontaining dyeing solution was installed in a stainless steel chamber with air cooling under irradiation. The TiO2 powder wascharacterized by XRD observation and it was shown that the nanoparticles could be identified as 73 nm anatase crystals. Theeffects of operational parameters such as light intensity (0-114 W/m2, initial dye concentration (10-30 mg/L, and TiO2 powderloading (0.5-1.5 g/L on the decolorization of dye samples were examined. The photocatalytic decolorization rate depended onthe pollutant’s structure, such that the MG dye could be removed faster than the RB dye. Decolorization efficiency (% of thephotocatalytic system increased with increasing TiO2 loading and light intensity; however, it decreased with increasing initialdye concentration. A loading of 1.5 g TiO2/L, initial dye concentration of 20 mg/L, and light intensity of 114 W/m2 were foundto yield the highest removal efficiency of dye solution based on time requirement. The kinetics are of first order and dependon the TiO2 powder loading and dye structure. The research had a perfect application foreground.

  3. Phosphorus doped TiO2 as oxygen sensor with low operating temperature and sensing mechanism

    International Nuclear Information System (INIS)

    Han, Zhizhong; Wang, Jiejie; Liao, Lan; Pan, Haibo; Shen, Shuifa; Chen, Jianzhong

    2013-01-01

    Nano-scale TiO 2 powders doped with phosphorus were prepared by sol–gel method. The characterization of the materials was performed by XRD, BET, FT-IR spectroscopy, Zeta potential measurement and XPS analysis. The results indicate that the phosphorus suppresses the crystal growth and phase transformation and, at the same time, increases the surface area and enhances the sensitivity and selectivity for the P-doped TiO 2 oxygen sensors. In this system, the operating temperature is low, only 116 °C, and the response time is short. The spectra of FT-IR and XPS show that the phosphorus dopant presents as the pentavalent-oxidation state in TiO 2 , further phosphorus can connect with Ti 4+ through the bond of Ti-O-P. The positive shifts of XPS peaks indicate that electron depleted layer of P-doped TiO 2 is narrowed compared with that of pure TiO 2 , and the results of Zeta potential illuminate that the density of surface charge carrier is intensified. The adsorptive active site and Lewis acid characteristics of the surface are reinforced by phosphorus doping, where phosphorus ions act as a new active site. Thus, the sensitivity of P-doped TiO 2 is improved, and the 5 mol% P-doped sample has the optimal oxygen sensing properties.

  4. Improved hydrogen storage properties of MgH2 catalyzed with TiO2

    Science.gov (United States)

    Jangir, Mukesh; Meena, Priyanka; Jain, I. P.

    2018-05-01

    In order to improve the hydrogenation properties of the MgH2, various concentration of rutile Titanium Oxide (TiO2) (X wt%= 5, 10, 15 wt %) is added to MgH2 by ball milling and the catalytic effect of TiO2 on hydriding/dehydriding properties of MgH2 has been investigated. Result shows that the TiO2 significantly reduced onset temperature of desorption. Onset temperature as low as 190 °C were observed for the MgH2-15 wt% TiO2 sample which is 60 °C and 160 °C lower than the as-milled and as-received MgH2. Fromm the Kissinger plot the activation energy of 15 wt% TiO2 added sample is calculated to be -75.48 KJ/mol. These results indicate that the hydrogenation properties of MgH2-TiO2 have been improved compared to the as-milled and as-received MgH2. Furthermore, XRD and XPS were performed to characterize the structural evolution upon milling and dehydrogenation.

  5. Antimicrobial Activity of TiO2 Nanoparticle-Coated Film for Potential Food Packaging Applications

    Directory of Open Access Journals (Sweden)

    Siti Hajar Othman

    2014-01-01

    Full Text Available Recent uses of titanium dioxide (TiO2 have involved various applications which include the food industry. This study aims to develop TiO2 nanoparticle-coated film for potential food packaging applications due to the photocatalytic antimicrobial property of TiO2. The TiO2 nanoparticles with varying concentrations (0–0.11 g/ 100 mL organic solvent were coated on food packaging film, particularly low density polyethylene (LDPE film. The antimicrobial activity of the films was investigated by their capability to inactivate Escherichia coli (E. coli in an actual food packaging application test under various conditions, including types of light (fluorescent and ultraviolet (UV and the length of time the film was exposed to light (one–three days. The antimicrobial activity of the TiO2 nanoparticle-coated films exposed under both types of lighting was found to increase with an increase in the TiO2 nanoparticle concentration and the light exposure time. It was also found that the antimicrobial activity of the films exposed under UV light was higher than that under fluorescent light. The developed film has the potential to be used as a food packaging film that can extend the shelf life, maintain the quality, and assure the safety of food.

  6. Novel preparation and photocatalytic activity of one-dimensional TiO2 hollow structures

    International Nuclear Information System (INIS)

    Yu Huogen; Yu Jiaguo; Cheng Bei; Liu Shengwei

    2007-01-01

    Usually, templated methods include two important steps: the coating of nanocrystals on the surface of the templates and the removal of the templates. In this study, one-dimensional TiO 2 hollow structures, based on the template-directed deposition and then in situ template-sacrificial reaction (or dissolution), were prepared by a one-step template method using vanadium oxide nanobelts as the templates and TiF 4 as the precursor at 60 deg. C. The coating of TiO 2 nanoparticles on the surface of the templates was accompanied with the dissolution of vanadium oxide nanobelts by HF produced during the hydrolysis of TiF 4 in the reaction solution. It was found that the prepared one-dimensional TiO 2 hollow structures with a mesoporous wall were composed of TiO 2 nanoparticles with a diameter of 10-55 nm, resulting in a large specific surface area (77.2 m 2 g -1 ) and high pore volume (0.13 cm 3 g -1 ), and the wall thickness of the TiO 2 hollow structures could be easily controlled by adjusting the precursor concentration of TiF 4 . The photocatalytic activity experiment indicated that the prepared one-dimensional TiO 2 hollow structures, which could be readily separated from a slurry system after photocatalytic reaction, exhibited obvious photocatalytic activity for the photocatalytic degradation of methyl orange aqueous solution

  7. Adsorption performance of titanium dioxide (TiO2) coated air filters for volatile organic compounds.

    Science.gov (United States)

    Zhong, Lexuan; Lee, Chang-Seo; Haghighat, Fariborz

    2012-12-01

    The photocatalytic oxidation (PCO) technology as an alternative method for air purification has been studied for decades and a variety of PCO models indicate that the adsorption of reactants on the catalyst surface is one of the major physical and chemical processes occurring at a heterogeneous photocatalytic reaction. However, limited study explored the adsorption effect of a photocatalyst. This study carried out a systematic evaluation of adsorption performance of titanium dioxide (TiO(2)) coated fiberglass fibers (FGFs), TiO(2) coated carbon cloth fibers (CCFs), and original CCFs air filters at various relative humidity conditions for nine volatile organic compounds. TiO(2)/FGFs, TiO(2)/CCFs, and CCFs were characterized by SEM for morphology and N(2) adsorption isotherm for BET surface area and pore structure. A bench-scale adsorption test setup was constructed and adsorption tests were performed at various relative humidity conditions and four different injected concentrations for each compound. The isothermal adsorption curves at low concentration levels were obtained and they were well described by Langmuir isotherm model. It was noticed that there were significant differences between the adsorption behaviors and photocatalytic activities of TiO(2)/FGFs and TiO(2)/CCFs. It was concluded that adsorption performance is closely related to the characteristics of substrates and therefore, the development of a substrate with high adsorption ability is a promising trend for improving the performance of the UV-PCO technology. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Microwave synthesized nanostructured TiO2-activated carbon composite electrodes for supercapacitor

    International Nuclear Information System (INIS)

    Selvakumar, M.; Bhat, D. Krishna

    2012-01-01

    Highlights: ► Nanostructure TiO 2 has been prepared by a microwave assisted synthesis method. ► Microwave irradiation was varied with time duration on the formation of nanoparticles. ► TiO 2 -activate carbon show very good specific capacitance for supercapacitor. ► Electrochemical properties were studied on electroanalytical techniques. - Abstract: Electrochemical properties of a supercapacitor based on nanocomposite electrodes of activated carbon with TiO 2 nano particles synthesized by a microwave method have been determined. The TiO 2 /activated carbon nanocomposite electrode with a composition of 1:3 showed a specific capacitance 92 Fg −1 . The specific capacitance of the electrode decreased with increase in titanium dioxide content. The p/p symmetrical supercapacitor fabricated with TiO 2 /activated carbon composite electrodes showed a specific capacitance of 122 Fg −1 . The electrochemical behavior of the neat TiO 2 nanoparticles has also been studied for comparison purpose. The galvanostatic charge–discharge test of the fabricated supercapacitor showed that the device has good coulombic efficiency and cycle life. The specific capacitance of the supercapacitor was stable up to 5000 cycles at current densities of 2, 4, 6 and 7 mA cm −2 .

  9. Preparation of Nanoporous TiO2 Electrodes for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Hsiue-Hsyan Wang

    2011-01-01

    Full Text Available Nano-porous TiO2 thin films have been widely used as the working electrodes in dye-sensitized solar cells (DSSCs. In this work, the phase-pure anatase TiO2 (a-TiO2 and rutile TiO2 (r-TiO2 have been prepared using hydrothermal processes. The investigation of photo-to-electron conversion efficiency of DSSCs fabricated from mixed-TiO2 with a-TiO2 and r-TiO2 ratio of 80 : 20 (A8R2 was performed and compared to that from commercial TiO2 (DP-25. The results showed higher efficiency of DSSC for A8R2 cells with same dependence of cell efficiency on the film thickness for both A8R2 and DP-25 cells. The best efficiency obtained in this work is 5.2% from A8R2 cell with TiO2 film thickness of 12.0 μm. The correlation between the TiO2 films thickness and photoelectron chemical properties of DSSCs fabricated from A8R2 and DP-25 was compared and discussed.

  10. Biocompatibility and Surface Properties of TiO2 Thin Films Deposited by DC Magnetron Sputtering

    Science.gov (United States)

    López-Huerta, Francisco; Cervantes, Blanca; González, Octavio; Hernández-Torres, Julián; García-González, Leandro; Vega, Rosario; Herrera-May, Agustín L.; Soto, Enrique

    2014-01-01

    We present the study of the biocompatibility and surface properties of titanium dioxide (TiO2) thin films deposited by direct current magnetron sputtering. These films are deposited on a quartz substrate at room temperature and annealed with different temperatures (100, 300, 500, 800 and 1100 °C). The biocompatibility of the TiO2 thin films is analyzed using primary cultures of dorsal root ganglion (DRG) of Wistar rats, whose neurons are incubated on the TiO2 thin films and on a control substrate during 18 to 24 h. These neurons are activated by electrical stimuli and its ionic currents and action potential activity recorded. Through X-ray diffraction (XRD), the surface of TiO2 thin films showed a good quality, homogeneity and roughness. The XRD results showed the anatase to rutile phase transition in TiO2 thin films at temperatures between 500 and 1100 °C. This phase had a grain size from 15 to 38 nm, which allowed a suitable structural and crystal phase stability of the TiO2 thin films for low and high temperature. The biocompatibility experiments of these films indicated that they were appropriated for culture of living neurons which displayed normal electrical behavior. PMID:28788667

  11. Ultra-fine structural characterization and bioactivity evaluation of TiO2 nanotube layers.

    Science.gov (United States)

    Jang, JaeMyung; Kwon, TaeYub; Kim, KyoHan

    2008-10-01

    For an application as biomedical materials of high performance with a good biocompatibility, the TiO2 nanotube-type oxide film on Ti substrate has been fabricated by electrochemical method, and the effects of surface characteristics of TiO2 naotube layer have been investigated. The surface morphology of TiO2 nanotube layer depends on factors such as anodizing time, current density, and electrolyte temperature. Moreover, the cell and pore size gradually were increased with the passage of anodizing time. X-ray diffraction (XRD) results indicated that the TiO2 nanotube layer formed in acidic electrolytes was mainly composed of anatase structure containing rutile. From the analysis of chemical states of TiO2 nanotube layer using X-ray photoelectron spectroscopy (XPS), Ti2p, P2p and O1s were observed in the nanotubes layer, which were penetrated from the electrolyte into the oxide layer during anodic process. The incorporated phosphate species were found mostly in the forms of HPO4-, PO4-, and PO3-. From the result of biological evaluation in simulated body fluid (SBF) the TiO2 nanotube layer was effective for bioactive property.

  12. Photoelectrolysis of water using heterostructural composite of TiO2 nanotubes and nanoparticles

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  13. Nanocomposites of TiO2/cyanoethylated cellulose with ultra high dielectric constants

    International Nuclear Information System (INIS)

    Madusanka, Nadeesh; Shivareddy, Sai G; Hiralal, Pritesh; Choi, Youngjin; Amaratunga, Gehan A J; Eddleston, Mark D; Oliver, Rachel A

    2016-01-01

    A novel dielectric nanocomposite containing a high permittivity polymer, cyanoethylated cellulose (CRS) and TiO 2 nanoparticles was successfully prepared with different weight percentages (10%, 20% and 30%) of TiO 2 . The intermolecular interactions and morphology within the polymer nanocomposites were analysed. TiO 2 /CRS nanofilms on SiO 2 /Si wafers were used to form metal–insulator–metal type capacitors. Capacitances and loss factors in the frequency range of 1 kHz–1 MHz were measured. At 1 kHz CRS-TiO 2 nanocomposites exhibited ultra high dielectric constants of 118, 176 and 207 for nanocomposites with 10%, 20% and 30% weight of TiO 2 respectively, significantly higher than reported values of pure CRS (21), TiO 2 (41) and other dielectric polymer-TiO 2 nanocomposite films. Furthermore, all three CRS-TiO 2 nanocomposites show a loss factor <0.3 at 1 kHz and low leakage current densities (10 −6 –10 −7 A cm −2 ). Leakage was studied using conductive atomic force microscopy and it was observed that the leakage is associated with TiO 2 nanoparticles embedded in the CRS polymer matrix. A new class of ultra high dielectric constant hybrids using nanoscale inorganic dielectrics dispersed in a high permittivity polymer suitable for energy management applications is reported. (paper)

  14. Construction of anatase/rutile TiO2 hollow boxes for highly efficient photocatalytic performance

    Science.gov (United States)

    Jia, Changchao; Zhang, Xiao; Yang, Ping

    2018-02-01

    Hollow TiO2 hierarchical boxes with suitable anatase and rutile ratios were designed for photocatalysis. The unique hierarchical structure was fabricated via a Topotactic synthetic method. CaTiO3 cubes were acted as the sacrificial templates to create TiO2 hollow hierarchical boxes with well-defined phase distribution. The phase composition of the hollow TiO2 hierarchical boxes is similar to that of TiO2 P25 nanoparticles (∼80% anatase, and 20% rutile). Compared with nanaoparticles, TiO2 hollow boxes with hierarchical structures exhibited an excellent performance in the photocatalytic degradation of methylene blue organic pollutant. Quantificationally, the degradation rate of the hollow boxes is higher than that of TiO2 P25 nanoparticles by a factor of 2.7. This is ascribed that hollow structure provide an opportunity for using incident light more efficiently. The surface hierarchical and well-organized porous structures are beneficial to supply more active sites and enough transport channels for reactant molecules. The boxes consist of single crystal anatase and rutile combined well with each other, which gives photon-generated carriers transfer efficiently.

  15. Sputtered PdO Decorated TiO2 Sensing Layer for a Hydrogen Gas Sensor

    Directory of Open Access Journals (Sweden)

    Jeong Hoon Lee

    2018-01-01

    Full Text Available We report a sputtered PdO decorated TiO2 sensing layer by radiofrequency (RF sputtering methods and demonstrated gas sensing performance for H2 gas. We prepared sputtered anatase TiO2 sensing films with 200 nm thickness and deposited a Pd layer on top of the TiO2 films with a thickness ranging from 3 nm to 13 nm. Using an in situ TiO2/Pd multilayer annealing process at 550°C for 1 hour, we observed that Pd turns into PdO by Auger electron spectroscopy (AES depth profile and confirmed decorated PdO on TiO2 sensing layer from scanning electron microscope (SEM and atomic-force microscope (AFM. We also observed a positive sensing signal for 3, 4.5, and 6.5 nm PdO decorated TiO2 sensor while we observed negative output signal for a 13.5 nm PdO decorated one. Using a microheater platform, we acquired fast response time as ~11 sec and sensitivity as 6 μV/ppm for 3 nm PdO under 33 mW power.

  16. Photocatalytic properties of nanocrystalline TiO2 thin film with Ag additions

    International Nuclear Information System (INIS)

    Chang, C.-C.; Lin, C.-K.; Chan, C.-C.; Hsu, C.-S.; Chen, C.-Y.

    2006-01-01

    In the present study, nanocrystalline TiO 2 /Ag composite thin films were prepared by a sol-gel spin coating technique. While, by introducing polystyrene (PS) microspheres, porous TiO 2 /Ag films were obtained after calcining at a temperature of 500 o C. The as-prepared TiO 2 and TiO 2 /Ag thin films were characterized by X-ray diffractometry, and scanning electron microscopy to reveal the structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methylene blue under UV irradiation. After 500 o C calcination, the microstructure of PS-TiO 2 film without Ag addition exhibited a sponge-like microstructure while significant sintering effect was noticed with Ag additions and the films exhibited a porous microstructure. Meanwhile, coalescence of nanocrystalline anatase-phase TiO 2 can be observed with respect to the sharpening of XRD diffraction peaks. The photodegradation of porous TiO 2 doped with 1 mol% Ag exhibited the best photocatalytic efficiency where 72% methylene blue can be decomposed after UV exposure for 12 h

  17. Love Wave Ultraviolet Photodetector Fabricated on a TiO2/ST-Cut Quartz Structure

    Directory of Open Access Journals (Sweden)

    Walter Water

    2014-01-01

    Full Text Available A TiO2 thin film deposited on a 90° rotated 42°45′ ST-cut quartz substrate was applied to fabricate a Love wave ultraviolet photodetector. TiO2 thin films were grown by radio frequency magnetron sputtering. The crystalline structure and surface morphology of TiO2 thin films were examined using X-ray diffraction, scanning electron microscope, and atomic force microscope. The effect of TiO2 thin film thickness on the phase velocity, electromechanical coupling coefficient, temperature coefficient of frequency, and sensitivity of ultraviolet of devices was investigated. TiO2 thin film increases the electromechanical coupling coefficient but decreases the temperature coefficient of frequency for Love wave propagation on the 90° rotated 42°45′ ST-cut quartz. For Love wave ultraviolet photodetector application, the maximum insertion loss shift and phase shift are 2.81 dB and 3.55 degree at the 1.35-μm-thick TiO2 film.

  18. Eu"2"+ doped TiO_2 nano structures synthesized by HYSYCVD for thermoluminescence dosimetry

    International Nuclear Information System (INIS)

    Perez A, J. A.; Leal C, A. L.; Melendrez A, R.; Barboza F, M.

    2016-10-01

    Titania (TiO_2) has attracted interest owing his potential applications as dosimetry material given his excellent optical, electrical and thermal properties and the ability to shape his structure make TiO_2 suitable for research and dosimetry applications. In this work, a systematic study to know the magnitude of processing parameters influence on thermoluminescent properties of undoped (TiO_2) and doped (TiO_2:Eu"2"+) nano materials obtained by hybrid precursor systems chemical vapor deposition (HYSYCVD) technique is presented. Synthesis of one dimension nano structures of TiO_2:Eu"2"+ was carried out using K_2TiF_6 and EuCl_2 as dopant at 0.5, 1, 2.5 and 5 wt %. The nano structures samples were irradiated with β-ray in a doses range of 0.083-3000 Gy. All thermoluminescence (Tl) glow curves showed 3 broad Tl peaks around 373, 473 and 573 K, and a dosimetric linear behavior from 0.083 to 300 Gy. The Tl has a good reproducibility, with deviations of around 5%, making these TiO_2:Eu"2"+ nano materials suitable for dosimetric applications. (Author)

  19. Exposure to TiO2 nanoparticles increases Staphylococcusaureusinfection of HeLa cells

    Science.gov (United States)

    Xu, Yan; Wei, Ming-Tzo; Walker, Stephen. G.; Wang, Hong Zhan; Gondon, Chris; Brink, Peter; Guterman, Shoshana; Zawacki, Emma; Applebaum, Eliana; Rafailovich, Miriam; Ou-Yang, H. Daniel; Mironava, Tatsiana

    TiO2 is one of the most common nanoparticles in industry from food additives to energy generation. Even though TiO2 is also used as an anti-bacterial agent in combination with UV, we found that, in the absence of UV, exposure of HeLa cells to TiO2 nanoparticles largely increased their risk of bacterial invasion. HeLa cells cultured with low dosage rutile and anatase TiO2 nanoparticles (0.1 mg/ml) for 24 hrs prior to exposure to bacteria had 350% and 250% respectively more bacteria infected per cell. The increase was attributed to increased LDH leakage, and changes in the mechanical response of the cell membrane. On the other hand, macrophages exposed to TiO2 particles ingested 40% fewer bacteria, further increasing the risk of infection. In combination, these two factors raise serious concerns regarding the impact of exposure to TiO2 nanoparticles on the ability of organisms to resist bacterial infection.

  20. TiO2 (NanoParticles Extracted from Sugar-Coated Confectionery

    Directory of Open Access Journals (Sweden)

    Martina Lorenzetti

    2017-01-01

    Full Text Available As the debate about TiO2 food additive safety is still open, the present study focuses on the extraction and characterisation of TiO2 (nanoparticles added as a whitening agent to confectionary products, that is, chewing gum pellets. The aim was to (1 determine the colloidal properties of suspensions mutually containing TiO2 and all other chewing gum ingredients in biologically relevant media (preingestion conditions; (2 characterise the TiO2 (nanoparticles extracted from the chewing gum coating (after ingestion; and (3 verify their potential photocatalysis. The particle size distribution, in agreement with the zeta potential results, indicated that a small but significant portion of the particle population retained mean dimensions close to the nanosize range, even in conditions of moderate stability, and in presence of all other ingredients. The dispersibility was enhanced by proteins (i.e., albumin, which acted as surfactants and reduced particle size. The particle extraction methods involved conventional techniques and no harmful chemicals. The presence of TiO2 particles embedded in the sugar-based coating was confirmed, including 17–30% fraction in the nanorange (<100 nm. The decomposition of organics under UV irradiation proved the photocatalytic activity of the extracted (nanoparticles. Surprisingly, photocatalysis occurred even in presence of an amorphous SiO2 layer surrounding the TiO2 particles.

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

    Science.gov (United States)

    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. Copyright © 2013 Elsevier Inc. All rights reserved.

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

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  3. Production and Characterization of (004) Oriented Single Anatase TiO2 Films

    Science.gov (United States)

    Atay, Ferhunde; Akyuz, Idris; Cergel, Muge Soyleyici; Erdogan, Banu

    2018-02-01

    Highly (004) oriented anatase TiO2 films have been successfully obtained by an inexpensive ultrasonic spray pyrolysis technique at low substrate temperatures and without additional annealing. X-ray diffraction analysis, ultraviolet-visible spectroscopy and field emission scanning electron microscopy were used to analyze the structural, optical and surface properties of the films. By using the less reported TiCl4 solution, the optical band gap values falling into the visible region (between 2.70 eV and 2.92 eV) have been obtained for all films. Spectroscopic ellipsometry technique has been used to determine the dispersive refractive index and extinction coefficient of TiO2 films. Possible electrical conduction mechanisms in TiO2 films have been examined using temperature dependent conductivity measurements in the temperature range of 78-300 K. At room temperature, electrical resistivity values of TiO2 films change between 1.68 × 104 Ω cm and 5.88 × 104 Ω cm. Considering the analyzed parameters with respect to substrate temperature, this work refers to the properties of anatase TiO2 films that are strongly correlated to the growth direction, namely (004). As a result, (004) oriented anatase TiO2 films with appropriate optical band gap values are promising materials for technological applications, especially for photocatalysts.

  4. Multi-Layered TiO2 Films towards Enhancement of Escherichia coli Inactivation

    Directory of Open Access Journals (Sweden)

    Sorachon Yoriya

    2016-09-01

    Full Text Available Crystalline TiO2 has shown its great photocatalytic properties in bacterial inactivation. This work presents a design fabrication of low-cost, layered TiO2 films assembled reactors and a study of their performance for a better understanding to elucidate the photocatalytic effect on inactivation of E. coli in water. The ability to reduce the number of bacteria in water samples for the layered TiO2 composing reactors has been investigated as a function of time, while varying the parameters of light sources, initial concentration of bacteria, and ratios of TiO2 film area and volume of water. Herein, the layered TiO2 films have been fabricated on the glass plates by thermal spray coating prior to screen printing, allowing a good adhesion of the films. Surface topology and crystallographic phase of TiO2 for the screen-printed active layer have been characterized, resulting in the ratio of anatase:rutile being 80:20. Under exposure to sunlight and a given condition employed in this study, the optimized film area:water volume of 1:2.62 has shown a significant ability to reduce the E. coli cells in water samples. The ratio of surface area of photocatalytic active base to volume of water medium is believed to play a predominant role facilitating the cells inactivation. The kinetic rate of inactivation and its behavior are also described in terms of adsorption of reaction species at different contact times.

  5. Origin of visible-light sensitivity in N-doped TiO2 films

    International Nuclear Information System (INIS)

    Nakano, Yoshitaka; Morikawa, Takeshi; Ohwaki, Takeshi; Taga, Yasunori

    2007-01-01

    We report on visible-light sensitivity in N-doped TiO 2 (TiO 2 :N) films that were deposited on n + -GaN/Al 2 O 3 substrates by reactive magnetron sputtering and subsequently crystallized by annealing at 550 deg. C in flowing N 2 gas. The N-doping concentration was ∼8.8%, as determined by X-ray photoelectron spectroscopy measurements. From transmission electron microscopic observations and optical absorption measurements, yellow-colored TiO 2 :N samples showed an enhanced granular structure and strong absorption in the visible-light region. Photoelectron spectroscopy in air measurements showed a noticeable decrease in ionization energy of TiO 2 by the N doping. Deep-level optical spectroscopy measurements revealed two characteristic deep levels located at ∼1.18 and ∼2.48 eV below the conduction band. The 1.18 eV level is probably attributable to the O vacancy state and can be active as an efficient generation-recombination center. The pronounced 2.48 eV band is newly introduced by the N doping and contributes to band-gap narrowing of TiO 2 by mixing with the O 2p valence band. Therefore, this localized intraband is probably one origin of visible-light sensitivity in TiO 2 :N

  6. Hydrothermal synthesis spherical TiO2 and its photo-degradation property on salicylic acid

    International Nuclear Information System (INIS)

    Guo Wenlu; Liu Xiaolin; Huo Pengwei; Gao Xun; Wu Di; Lu Ziyang; Yan Yongsheng

    2012-01-01

    Anatase TiO 2 spheres have been prepared using hydrothermal synthesis. The prepared spheres were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-vis diffuse reflectance spectra (UV-vis DRS). The TiO 2 consisted of well-defined spheres with size of 3-5 μm. The photocatalytic activity of spherical TiO 2 was determined by degradation of salicylic acid under visible light irradiation. It was revealed that the degradation rate of the spherical TiO 2 which was processed at 150 °C for 48 h could reach 81.758%. And the kinetics of photocatalytic degradation obeyed first-order kinetic, which the rate constant value was 0.01716 S -1 of the salicylic acid onto TiO 2 (temperature: 150, time: 48 h). The kinetics of adsorption followed the pseudo-second-order model and the rate constant was 1.2695 g mg -1 of the salicylic acid onto TiO 2 (temperature: 150, time: 48 h).

  7. Experimental measurement and modelling of reactive species generation in TiO2 nanoparticle photocatalysis.

    Science.gov (United States)

    Turolla, Andrea; Piazzoli, Andrea; Budarz, Jeffrey Farner; Wiesner, Mark R; Antonelli, Manuela

    2015-07-01

    The generation of reactive species in titanium dioxide (TiO 2 ) nanoparticle photocatalysis was assessed in a laboratory scale setup, in which P25 Aeroxide TiO 2 suspensions were photoactivated by means of UV-A radiation. Photogenerated holes and hydroxyl radicals were monitored over time by observing their selective reaction with probe compounds, iodide and terephthalic acid, respectively. TiO 2 aggregate size and structure were characterized over the reaction time. Reactive species quenching was then described by a model, accounting for radiative phenomena, TiO 2 nanoparticle aggregation and kinetic reactions. The interaction between iodide and photogenerated holes was influenced by iodide adsorption on TiO 2 surface, described by a Langmuir-Hinshelwood mechanism, whose parameters were studied as a function of TiO 2 concentration and irradiation time. Iodide oxidation was effectively simulated by modelling the reaction volume as a completely stirred two-dimensional domain, in which irradiation phenomena were described by a two-flux model and the steady state for reactive species was assumed. The kinetic parameters for iodide adsorption and oxidation were estimated and successfully validated in a different experimental setup. The same model was adapted to describe the oxidation of terephthalic acid by hydroxyl radicals. The kinetic parameters for terephthalic acid oxidation were estimated and validated, while the issues in investigating the interaction mechanisms among the involved species have been discussed. The sensitivity of operating parameters on model response was assessed and the most relevant parameters were highlighted.

  8. Formation of textured microstructure by mist deposition of TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Qin, Gang; Watanabe, Akira

    2013-01-01

    Unique and various textured TiO 2 films have been easily fabricated by mist deposition method on silicon and glass substrates with mild preparation conditions. Two kinds of TiO 2 nanoparticle with different shape, size, and crystal form were used as starting material, which resulted in a simple preparation process under low temperature and ordinary pressure. It was easy to control the thickness, morphology, and roughness of textured TiO 2 film by adjusting the mist deposition conditions such as deposition time, temperature, and the shape and size of nanoparticles. The optical properties of textured TiO 2 films before and after spin coating of Ag nanoparticles were investigated. The angular dependence of the reflectance was obviously reduced by textured TiO 2 surface and such effect was enhanced by Ag nanoparticles coating. A broad plasmon band of Ag grains was observed in the absorption spectrum of the textured Ag nanoparticle-coated TiO 2 film

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  10. TiO2-based photocatalytic disinfection of microbes in aqueous media: A review.

    Science.gov (United States)

    Laxma Reddy, P Venkata; Kavitha, Beluri; Kumar Reddy, Police Anil; Kim, Ki-Hyun

    2017-04-01

    The TiO 2 based photocatalyst has great potential for the disinfection/inactivation of harmful pathogens (such as E.coli in aqueous media) along with its well-known usefulness on various chemical pollutants. The disinfection property of TiO 2 is primarily attributed to surface generation of reactive oxygen species (ROS) as well as free metal ions formation. Furthermore, its disinfection capacity and overall performance can be significantly improved through modifications of the TiO 2 material. In this review, we provide a brief survey on the effect of various TiO 2 materials in the disinfection of a wide range of environmentally harmful microbial pathogens (e.g., bacteria, fungi, algae, and viruses) in aqueous media. The influencing factors (such as reactor design, water chemistry, and TiO 2 modifications) of such processes are discussed along with the mechanisms of such disinfection. It is believed that the combined application of disinfection and decontamination will greatly enhance the utilization of TiO 2 photocatalyst as a potential alternative to conventional methods of water purification. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Coaxial nanofibers containing TiO2 in the shell for water treatment applications

    Science.gov (United States)

    Kizildag, N.; Geltmeyer, J.; Ucar, N.; De Buysser, K.; De Clerck, K.

    2017-10-01

    In recent years, the basic electrospinning setup has undergone many modifications carried out to enhance the quality and improve the functionality of the resulting nanofibers. Being one of these modifications, coaxial electrospinning has attracted great attention. It enables to use different materials in nanofiber production and produce multi-layered and functional nanofibers in one step. In this study, TiO2 has been added to the shell layer of coaxial nanofibers to develop functional nanofibers which may be used in water treatment applications. The coaxial nanofibers containing TiO2 in the shell layer are compared to uniaxial nanofibers containing TiO2 in bulk fiber structure, regarding their morphology and photocatalytic activity. Uniform uniaxial and coaxial nanofibers with TiO2 were obtained. The average nanofiber diameter of coaxial nanofibers were higher. Coaxial nanofibers, which contained lower amount of TiO2, displayed similar performance to uniaxial nanofibers with TiO2 in terms of photocatalytic degradation ability against isoproturon.

  12. Chalcogenide Sensitized Carbon Based TiO2 Nanomaterial For Solar Driven Applications

    Science.gov (United States)

    Pathak, Pawan

    The demand for renewable energy is growing because fossils fuels are depleting at a rapid pace. Solar energy an abundant green energy resource. Utilizing this resource in a smart manner can resolve energy-crisis related issues. Sun light can be efficiently harvested using semiconductor based materials by utilizing photo-generated charges for numerous beneficial applications. The main goal of this thesis is to synthesize different nanostructures of TiO2, develop a novel method of coupling and synthesizing chalcogenide nanocrystals with TiO2 and to study the charge transportation effects of the various carbon allotropes in the chalcogenide nanocrystal sensitized TiO2 nanostructure. We have fabricated different nanostructures of TiO2 as solar energy harvesting materials. Effects of the different phases of TiO2 have also been studied. The anatase phase of TiO2 is more photoactive than the rutile phase of TiO2, and the higher dimension of the TiO2 can increase the surface area of the material which can produce higher photocurrent. Since TiO2 only absorbs in the UV range; to increase the absorbance TiO2 should be coupled to visible light absorbing materials. This dissertation presents a simple approach to synthesize and couple chalcogenide nanocrystals with TiO2 nanostructure to form a heterostructured composite. An atmospheric pressure based, single precursor, one-pot approach has been developed and tested to assemble chalcogenide nanocrystal on the TiO2 surface. Surface characterization using microscopy, X-ray diffraction, and elemental analysis indicates the formation of nanocrystals along the nanotube walls and inter-tubular spacing. Optical measurements indicate that the chalcogenide nanocrystals absorb in the visible region and demonstrate an increase in photocurrent in comparison to bare TiO2 nanostructure. The CdS synthesized TiO2 nanostructure produced the highest photocurrent as measured in the three electrode system. We have also assembled the PbS nanocrystal sensitized photoanode using the one pot method. Finally, the charge transportation effect of carbon allotropes has been studied. For this we assembled TiO2 conductive carbon chalcogenide nanocomposite system. Surface and elemental characterization using electron microscopy, EDX (energy dispersive x-ray) and x-ray diffraction pattern, provide the insights into the assembly of the nanostructure. Optical absorbance, Photo chronometry, Linear sweep voltammetry, and electrochemical impedance analysis have been used to provide opto-electronic performance of the material. We have studied the loading effect of various carbon allotropes, [fullerene (C 60), reduced graphene oxide (RGO), carbon nanotubes (CNTs), and graphene quantum dots (GQDs)], loading effect of chalcogenide, and effect of nitrogen doping on the carbon allotropes to optimize the performance of the heterostructure. This dissertation is expected to impact the materials synthesis strategies and assemble the nanostructures used in composite electrode driven applications in the area of photo electrochemistry, PV, solar-fuels, and other associated topics of energy storage and sensing.

  13. Enhanced electrochromic properties of TiO2 nanoporous film prepared based on an assistance of polyethylene glycol

    Science.gov (United States)

    Xu, Shunjian; Luo, Xiaorui; Xiao, Zonghu; Luo, Yongping; Zhong, Wei; Ou, Hui; Li, Yinshuai

    2017-01-01

    Polyethylene glycol (PEG) was employed as pore-forming agent to prepare TiO2 nanoporous film based on spin-coating a TiO2 nanoparticle mixed paste on fluorine doped tin oxide (FTO) glass. The electrochromic and optical properties of the obtained TiO2 film were investigated by cyclic voltammetry (CV), chronoamperometry (CA) and UV-Vis spectrophotometer. The results show that the PEG in the mixed paste endows the TiO2 film with well-developed porous structure and improves the uniformity of the TiO2 film, which are helpful for the rapid intercalation and extraction of lithium ions within the TiO2 film and the strengthening of the diffuse reflection of visible light in the TiO2 film. As a result, the TiO2 film derived from the mixed paste with PEG displays higher electrochemical activity and more excellent electrochromic performances compared with the TiO2 film derived from the mixed paste without PEG. The switching times of coloration/bleaching are respectively 10.16/5.65 and 12.77/6.13 s for the TiO2 films with PEG and without PEG. The maximum value of the optical contrast of the TiO2 film with PEG is 21.2% while that of the optical contrast of the TiO2 film without PEG is 14.9%. Furthermore, the TiO2 film with PEG has better stability of the colored state than the TiO2 film without PEG.

  14. Pilot-plant evaluation of TiO2 and TiO2-based hybrid photocatalysts for solar treatment of polluted water.

    Science.gov (United States)

    Andronic, Luminita; Isac, Luminita; Miralles-Cuevas, Sara; Visa, Maria; Oller, Isabel; Duta, Anca; Malato, Sixto

    2016-12-15

    Materials with photocatalytic and adsorption properties for advanced wastewater treatment targeting reuse were studied. Making use of TiO 2 as a well-known photocatalyst, Cu 2 S as a Vis-active semiconductor, and fly ash as a good adsorbent, dispersed mixtures/composites were prepared to remove pollutants from wastewater. X-ray diffraction, scanning electron microscopy, energy-dispersive X-Ray spectroscopy, atomic force microscopy, band gap energy, point of zero charge (pH pzc ) and BET porosity were used to characterize the substrates. Phenol, imidacloprid and dichloroacetic acid were used as pollutants for photocatalytic activity of the new photocatalysts. Experiments using the new dispersed powders were carried out at laboratory scale in two solar simulators and under natural solar irradiation at the Plataforma Solar de Almería, in a Compound Parabolic Collector (CPC) for a comparative analysis of pollutants removal and mineralization efficiencies, and to identify features that could facilitate photocatalyst separation and reuse. The results show that radiation intensity significantly affects the phenol degradation rate. The composite mixture of TiO 2 and fly ash is 2-3 times less active than sol-gel TiO 2 . Photodegradation kinetic data on the highly active TiO 2 are compared for pollutants elimination. Photodegradation of dichloroacetic acid was fast and complete after 90min in the CPC, while after 150min imidacloprid and phenol removal was 90% and 56% respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. The Influence of TiO2 Nanoparticles on LaFeO3/TiO2 Nanocomposites for Reduction of Aqueous Organic Dyes

    International Nuclear Information System (INIS)

    Afifah, N.; Saleh, R.

    2016-01-01

    A series of Lanthanum ferrite (LaFeO3) nanoparticles over titanium dioxide (TiO2) were synthesized using sol-gel method at room temperature by varying the loading of LaFeO3 on TiO2. The magnetic properties of samples were measured using vibrating sample magnetometer and photosonocatalytic activity towards the degradation of methylene blue under light (UV or visible) and ultrasound irradiation was also evaluated. The morphology and structure of the samples were characterized by field emission scanning electron microscope, energy dispersive analysis and X-ray diffraction. Furthermore the optical properties were also characterized by UV-visible diffuse reflectance. The experimental results showed that the prepared perovskites had sphere-like shape and strong visible light absorption. LaFeO3 demonstrated ferromagnetic properties and the magnetization decreased with the incorporation of TiO2 in the samples. However, the incorporation of TiO2 increased the photosonocatalytic activity and extended the photoresponding to UV light. (paper)

  16. Pilot-plant evaluation of TiO_2 and TiO_2-based hybrid photocatalysts for solar treatment of polluted water

    International Nuclear Information System (INIS)

    Andronic, Luminita; Isac, Luminita; Miralles-Cuevas, Sara; Visa, Maria; Oller, Isabel; Duta, Anca; Malato, Sixto

    2016-01-01

    Materials with photocatalytic and adsorption properties for advanced wastewater treatment targeting reuse were studied. Making use of TiO_2 as a well-known photocatalyst, Cu_2S as a Vis-active semiconductor, and fly ash as a good adsorbent, dispersed mixtures/composites were prepared to remove pollutants from wastewater. X-ray diffraction, scanning electron microscopy, energy-dispersive X-Ray spectroscopy, atomic force microscopy, band gap energy, point of zero charge (pH_p_z_c) and BET porosity were used to characterize the substrates. Phenol, imidacloprid and dichloroacetic acid were used as pollutants for photocatalytic activity of the new photocatalysts. Experiments using the new dispersed powders were carried out at laboratory scale in two solar simulators and under natural solar irradiation at the Plataforma Solar de Almería, in a Compound Parabolic Collector (CPC) for a comparative analysis of pollutants removal and mineralization efficiencies, and to identify features that could facilitate photocatalyst separation and reuse. The results show that radiation intensity significantly affects the phenol degradation rate. The composite mixture of TiO_2 and fly ash is 2-3 times less active than sol-gel TiO_2. Photodegradation kinetic data on the highly active TiO_2 are compared for pollutants elimination. Photodegradation of dichloroacetic acid was fast and complete after 90 min in the CPC, while after 150 min imidacloprid and phenol removal was 90% and 56% respectively.

  17. 1D TiO2 Nanostructures Prepared from Seeds Presenting Tailored TiO2 Crystalline Phases and Their Photocatalytic Activity for Escherichia coli in Water

    Directory of Open Access Journals (Sweden)

    Julieta Cabrera

    2018-01-01

    Full Text Available TiO2 nanotubes were synthesized by alkaline hydrothermal treatment of TiO2 nanoparticles with a controlled proportion of anatase and rutile. Tailoring of TiO2 phases was achieved by adjusting the pH and type of acid used in the hydrolysis of titanium isopropoxide (first step in the sol-gel synthesis. The anatase proportion in the precursor nanoparticles was in the 3–100% range. Tube-like nanostructures were obtained with an anatase percentage of 18 or higher while flake-like shapes were obtained when rutile was dominant in the seed. After annealing at 400°C for 2 h, a fraction of nanotubes was conserved in all the samples but, depending on the anatase/rutile ratio in the starting material, spherical and rod-shaped structures were also observed. The photocatalytic activity of 1D nanostructures was evaluated by measuring the deactivation of E. coli in stirred water in the dark and under UV-A/B irradiation. Results show that in addition to the bactericidal activity of TiO2 under UV-A illumination, under dark conditions, the decrease in bacteria viability is ascribed to mechanical stress due to stirring.

  18. Efectos de fotodegradación propiciados por recubrimientos de TiO2 y TiO2-SiO2 obtenidos por Sol-Gel

    Directory of Open Access Journals (Sweden)

    Rodriguez Paez, J. E.

    2008-10-01

    Full Text Available Photodegradation effect is widely used for water purification this contributes to preservation and protection of environment. Titanium oxide, (TiO2, is a compound that shows up this phenomenon. TiO2 is a semiconductor which may degradate pollutants through of a oxidation process. It permit the treatment of the residual water. It this work we has conformed coatings of TiO2 y TiO2-SiO2, utilized Sol-Gel method and investigated the degradation of the blue Methylene. For this, we introduced these coatings in the blue methylene solution which was illuminated with radiation of λ=365nm to activate its photocatilist properties. The structures of the coatings were characterized using Atomic Force Microscopy (AFM and X-ray Photoelectron Spectroscopy (XPS.El efecto de fotodegradación es ampliamente utilizado para la purificación del agua, acción que contribuye a la conservación y protección del medio ambiente; el óxido de titanio (TiO2 es uno de los semiconductores que pueden degradar contaminantes mediante procesos de oxidación, lo que lo hace apto para el tratamiento de aguas residuales. En este trabajo se conformaron recubrimientos de TiO2 y TiO2-SiO2, por el método Sol-Gel, y se estudio la degradación que experimentaba una solución de azul de metileno al introducirle estos recubrimientos e iluminarlos con una radiación de λ=365nm para activar su propiedad fotocatalítica. Los recubrimientos fueron caracterizados microestructuralmente utilizando Microscopía de Fuerza Atómica (MFA y Espectroscopía de Fotoelectrones de rayos X (XPS. Los resultados obtenidos de los ensayos de fotodegradación indican que los recubrimientos con una cantidad pequeña de silicio presentan un mayor efecto de fotodegradación indicando que el silicio puede generar puntos de anclaje que facilitan las reacciones de fotocatálisis. Por otro lado, la formación de centros activos, constituidos principalmente por carbono, también contribuyeron al desarrollo de estas reacciones.

  19. Nanoparticulate anatase TiO2 (TiO2 NPs) upregulates the expression of silkworm (Bombyx mori) neuropeptide receptor and promotes silkworm feeding, growth, and silking.

    Science.gov (United States)

    Ni, Min; Zhang, Hua; Li, Fan Chi; Wang, Bin Bin; Xu, Kai Zun; Shen, Wei De; Li, Bing

    2015-06-01

    Bombyx mori orphan G protein-coupled receptor, BNGR-A4, is the specific receptor of B. mori neuropeptide F (BmNPFR, neuropeptide F designated NPF). BmNPFR binds specifically and efficiently to B. mori neuropeptides BmNPF1a and BmNPF1b, which activates the ERK1/2 signaling pathway to regulate B. mori food intake and growth. Titanium dioxide nanoparticles (TiO2 NPs) can promote B. mori growth. However, whether the mechanisms of TiO2 NPs' effects are correlated with BmNPFR remains unknown. In this study, the effects of TiO2 NPs (5mg/L) feeding and BmNPFR-dsRNA injection on B. mori food intake and growth were investigated; after TiO2 NPs treatments, B. mori food intake, body weight, and cocoon shell weight were 5.82%, 4.64%, and 9.30% higher, respectively, than those of controls. The food intake, body weight, and cocoon shell weight of the BmNPFR-dsRNA injection group were reduced by 8.05%, 6.28%, and 6.98%, respectively, compared to the control. After TiO2 NPs treatment for 72h, the transcriptional levels of BmNPFR, BmNPF1a, and BmNPF1b in the midgut were 1.58, 1.43, and 1.34-folds, respectively, of those of the control, but 1.99, 2.26, and 2.19-folds, respectively, of the BmNPFR-dsRNA injection group; the phosphorylation level of MAPK was 24.03% higher than the control, while the phosphorylation level of BmNPFR-dsRNA injection group was 71.00% of control. The results indicated that TiO2 NPs affect B. mori feeding and growth through increasing the expression of BmNPFR. This study helps clarify the roles of BmNPF/BmNPFR system in TiO2 NPs' effects on B. mori feeding, growth, and development. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Preparation of pure TiO2 sorption material

    International Nuclear Information System (INIS)

    Špendlíková, Irena; Raindl, Jakub; Němec, Mojmír

    2013-01-01

    Among the natural or anthropogenic radionuclides of very low concentrations nowadays measured in environmental samples, the radionuclide of 236 U has been recently included. In these ultra-trace analyses, the purity of sorption materials is very important and the traditional preparation procedures have to be optimized to minimize possible contamination. In the case of the determination of natural concentration of 236 U ( 236 U/ 238 U ∼ 10 -10 - 10 -14 ), the sample treatment procedure has to be modified in order to eliminate possible contamination from anthropogenic 236 U that may result even in more than ten thousand times higher 236 U/ 238 U ratios. Many inorganic and organic materials have been proposed for the extraction of uranium. However, only several of them are suitable for the uranium sorption from the solutions of low uranium concentration, but relatively high salt content, such as fresh water, sea water etc. At the same time they have to meet other limiting parameters such as fast kinetics, chemical stability, and low costs. Among the inorganic sorption materials, titanium dioxide has been studied for years with promising results. Titanium dioxides can be prepared via the hydrolysis of titanium compounds, either inorganic salts or organic derivatives, but their properties strongly depend on the preparation conditions. In classical procedures, titanium dioxides are prepared from commercial inorganic salts, such as sulphates or chlorides, or even from industrial intermediates of the titanium white production. Typically, the resulting titanium dioxides are contaminated with uranium already from the origin. Assuming that most organic compounds do not contain uranium and that it is possible to find 'uranium free' water, titanium dioxide free of uranium contamination could be prepared by the hydrolysis of organic titanium derivatives. The aim of this study was to find a suitable way of pure titanium dioxide preparation and to optimize the preparation procedure with respect to the sorption properties of the resulting material towards uranium. Therefore, an organic compound, tetrabutylorthotitanate, was used for the preparation of a series of titanium dioxide samples. The conditions of the preparation procedure slightly varied (e.g. different washing solutions - ethanol, acetone or both) but the important steps like sample drying remain unchanged. One of the aspects which should be considered in the preparation of TiO 2 -based absorbers is the fact that the sorption properties of titanium dioxide strongly depend on the crystal structure and their capacities increase in order: rutile 2 : 1 N 2 at the temperature of 77 K. Sorption capacities for uranium were deduced from their sorption isotherms determined with fixed uranium concentration (20 mmol.L -1 ) and variable values of V/m (10 - 1400 mL.g -1 ). Based on this characterization, the most promising material has been chosen. In the future study, this material will be prepared in larger quantity using 'uranium free' water and used for the uranium concentration from environmental samples and for the consecutive determination of 236 u/ 238 U ratios using Accelerator Mass Spectrometry which will outline the contamination with anthropogenic 236 U and/or its natural abundance. (author)

  1. The design, fabrication, and photocatalytic utility of nanostructured semiconductors: focus on TiO2-based nanostructures

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    Arghya Narayan Banerjee

    2011-02-01

    Full Text Available Arghya Narayan BanerjeeSchool of Mechanical Engineering, Yeungnam University, Gyeongsan, South KoreaAbstract: Recent advances in basic fabrication techniques of TiO2-based nanomaterials such as nanoparticles, nanowires, nanoplatelets, and both physical- and solution-based techniques have been adopted by various research groups around the world. Our research focus has been mainly on various deposition parameters used for fabricating nanostructured materials, including TiO2-organic/inorganic nanocomposite materials. Technically, TiO2 shows relatively high reactivity under ultraviolet light, the energy of which exceeds the band gap of TiO2. The development of photocatalysts exhibiting high reactivity under visible light allows the main part of the solar spectrum to be used. Visible light-activated TiO2 could be prepared by doping or sensitizing. As far as doping of TiO2 is concerned, in obtaining tailored material with improved properties, metal and nonmetal doping has been performed in the context of improved photoactivity. Nonmetal doping seems to be more promising than metal doping. TiO2 represents an effective photocatalyst for water and air purification and for self-cleaning surfaces. Additionally, it can be used as an antibacterial agent because of its strong oxidation activity and superhydrophilicity. Therefore, applications of TiO2 in terms of photocatalytic activities are discussed here. The basic mechanisms of the photoactivities of TiO2 and nanostructures are considered alongside band structure engineering and surface modification in nanostructured TiO2 in the context of doping. The article reviews the basic structural, optical, and electrical properties of TiO2, followed by detailed fabrication techniques of 0-, 1-, and quasi-2-dimensional TiO2 nanomaterials. Applications and future directions of nanostructured TiO2 are considered in the context of various photoinduced phenomena such as hydrogen production, electricity generation via dye-sensitized solar cells, photokilling and self-cleaning effect, photo-oxidation of organic pollutant, wastewater management, and organic synthesis.Keywords: TiO2 nanostructure, fabrication techniques, doping in TiO2, TiO2-assisted photoactivity, solar hydrogen, TiO2-based dye-sensitized solar cells, TiO2 self-cleaning, organic synthesis

  2. Recovery of hexavalent chromium from water using photoactive TiO2-montmorillonite under sunlight

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    Ridha Djellabi

    2016-04-01

    Full Text Available Hexavalent chromium was removed from water under sunlight using a synthesized TiO2-montmorillonite (TiO2-M employing tartaric acid as a hole scavenger. Cr(VI species was then reduced to Cr(III species by electrons arising from TiO2 particles. After that, the produced Cr(III species  was transferred to montmorillonite  due to electrostatic attractions leading to  set free TiO2 particles for a further Cr(VI species reduction. Furthermore, produced Cr(III, after Cr(VI reduction, does not  penetrate into the solution. The results indicate that no dark adsorption of Cr(VI species on TiO2-M is present, however, the reduction of Cr(VI species under sunlight increased strongly as a function of tartaric acid concentration up to 60 ppm, for which the extent of reduction is maximum within 3 h. On the other hand, the reduction extent of Cr(VI species is maximum with an initial concentration of Cr(VI species lower than 30 ppm by the use of 0.2 g/L of TiO2-M. Nevertheless, the increase of the Cr(VI initial concentration led to increase the amount of Cr(VI species reduced (capacity of reduction until a Cr(VI concentration of 75 and 100 ppm, for which  it remained constant at around 221 mg/g. For comparison, the increase of Cr(VI species concentration in the case of the commercial TiO2 P25 under the same conditions exhibited its deactivation when the reduced amount decreased from 198.1 to 157.6 mg/g as the concentration increased from 75 to 100 ppm.

  3. Protein profiling as early detection biomarkers for TiO2 nanoparticle toxicity in Daphnia magna.

    Science.gov (United States)

    Sá-Pereira, Paula; Diniz, Mário S; Moita, Liliana; Pinheiro, Teresa; Mendonça, Elsa; Paixão, Susana M; Picado, Ana

    2018-05-01

    The mode of action for nanoparticle (NP) toxicity in aquatic organisms is not yet fully understood. In this work, a strategy other than toxicity testing was applied to Daphnia magna exposed to TiO 2 -NPs: the use of nuclear microscopy and the assessment of protein profile. D. magna is a keystone species broadly used as a model system in ecotoxicology. Titanium (Ti) was found in the D. magna digestive tract, mainly in the gut. The penetration of Ti into the epithelial region was greater at higher exposure levels and also observed in eggs in the brood pouch. The protein profile of individuals exposed to different concentrations showed that 2.8 and 5.6 mg/L TiO 2 -NP concentrations induced an over-expression of the majority of proteins, in particular proteins with molecular weight of ∼120, 85 and 15 kDa, while 11.2 mg/L TiO 2 -NP had an inhibitory effect on protein expression. The Matrix-assisted laser desorption ionization with tandem time of flight mass spectrometry (MALDI-TOF/TOF MS) analysis of these proteins consistently identified them as vitellogenin (Vtg)-like proteins, associated with enzymes involved in redox balance. These results indicate that Vtg-like proteins are up-regulated in D. magna exposed to TiO 2 -NPs. Vitellogenesis is associated with the reproduction system, suggesting that TiO 2 -NP exposure can impair reproduction by affecting this process. The precise mode of action of TiO 2 -NPs is still unclear and the results from this study are a first attempt to identify specific proteins as potential markers of TiO 2 -NP toxicity in D. magna, providing useful information for future research.

  4. Mesoporous TiO2 Micro-Nanometer Composite Structure: Synthesis, Optoelectric Properties, and Photocatalytic Selectivity

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    Kun Liu

    2012-01-01

    Full Text Available Mesoporous anatase TiO2 micro-nanometer composite structure was synthesized by solvothermal method at 180°C, followed by calcination at 400°C for 2 h. The as-prepared TiO2 was characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, transmission electron microscope (TEM, and Fourier transform infrared spectrum (FT-IR. The specific surface area and pore size distribution were obtained from N2 adsorption-desorption isotherm, and the optoelectric property of the mesoporous TiO2 was studied by UV-Vis absorption spectrum and surface photovoltage spectra (SPS. The photocatalytic activity was evaluated by photodegradation of sole rhodamine B (RhB and sole phenol aqueous solutions under simulated sunlight irradiation and compared with that of Degussa P-25 (P25 under the same conditions. The photodegradation preference of this mesoporous TiO2 was also investigated for an RhB-phenol mixed solution. The results show that the TiO2 composite structure consists of microspheres (∼0.5–2 μm in diameter and irregular aggregates (several hundred nanometers with rough surfaces and the average primary particle size is 10.2 nm. The photodegradation activities of this mesoporous TiO2 on both RhB and phenol solutions are higher than those of P25. Moreover, this as-prepared TiO2 exhibits photodegradation preference on RhB in the RhB-phenol mixture solution.

  5. Chromate enhanced visible light driven TiO2 photocatalytic mechanism on Acid Orange 7 photodegradation

    International Nuclear Information System (INIS)

    Wang, Yeoung-Sheng; Shen, Jyun-Hong; Horng, Jao-Jia

    2014-01-01

    Highlights: • Photocatalysis of Cr(VI) and TiO 2 were studied by ESR analysis on DMPO-OH signals. • Mechanism of Cr(VI)-enhanced by visible light was different from that by UV. • O 2 adsorbed on TiO 2 surfaces could react with Cr(VI) to lower photoenergy needed. • Even by UV, no TiO 2 photocatalysis was observed without O 2 solution. • Visible light and Cr(VI) redox reaction could activate TiO 2 and would yield ·OH. - Abstract: When hexavalent chromium (Cr(VI)) is added to a TiO 2 photocatalytic reaction, the decolorization and mineralization efficiencies of azo dyes Acid Orange 7 (AO7) are enhanced even though the mechanism is unclear. This study used 5,5-dimethyl-L-pyrroline-N-oxide (DMPO) as the scavenger and the analysis of Electron Spin Resonance (ESR) to investigate this enhancement effect by observing the hydroxyl radical (·OH) generation of the Cr(VI)/TiO 2 system under UV and visible light (Vis) irradiation. With Cr(VI), the decolorization efficiencies were approximately 95% and 62% under UV and Vis, and those efficiencies were 25% less in the absence of Cr(VI). The phenomena of the DMPO-OH signals during the ESR analysis under Vis 405 and 550 nm irradiation were obviously the enhancement effects of Cr(VI) in aerobic conditions. In anoxic conditions, the catalytic effects of Cr(VI) could not be achieved due to the lack of a redox reaction between Cr(VI) and the adsorbed oxygen at the oxygen vacancy sites on the TiO 2 surfaces . The results suggest that by introducing the agents of redox reactions such as chromate ions, we could lower the photoenergy of TiO 2 needed and allow Vis irradiation to activate photocatalysis

  6. Evaluate humidity sensing properties of novel TiO2–WO3 composite material

    International Nuclear Information System (INIS)

    Lin, Wang-De; Lai, De-Sheng; Chen, Min-Hung; Wu, Ren-Jang; Chen, Fu-Chou

    2013-01-01

    Graphical abstract: TiO 2 –WO 3 (1:1) showed better humidity sensing properties than others within the range of 12–90% relative humidity (RH), the response and recovery time were about 20 s and 160 s, respectively. Compared to the previous studies, the prepared sensor exhibits higher sensitivity (S = 451) and the low hysteresis value was around 0.13% at 32% RH. - Highlights: • Novel TiO 2 –WO 3 composite material was prepared for humidity sensor. • The sensor exhibits higher sensitivity (S = 451). • Low hysteresis value was around 0.13% at 32% RH. - Abstract: A novel TiO 2 –WO 3 composite material was prepared using a different proportion of TiO 2 and WO 3 to that investigated in previous studies. The obtained mesoporous material was characterized using X-ray diffraction, Fourier transform infrared spectrometry, transmission electron microscopy, energy dispersive X-ray spectroscopy, and N 2 adsorption-desorption techniques. The humidity-sensing properties were measured using an inductance, capacitance and resistance analyzer. The results demonstrated that the TiO 2 –WO 3 sample with a ratio of 1:1 showed better humidity sensing properties. Compared to previous studies, the prepared sensor exhibited higher sensitivity (S = 451) and the lower hysteresis value was around 0.13% at 32% RH. Complex impedance analysis indicated that the enhanced humidity sensitivity was probably due to spherical Brunauer–Emmett–Teller surface area and the hetero-junction between TiO 2 –WO 3 thin films, while the impedance varied about three orders of magnitude. Our results demonstrated the potential application of TiO 2 –WO 3 composite for fabricating high performance humidity sensors

  7. Enhanced photocatalytic degradation of dyes under sunlight using biocompatible TiO2 nanoparticles

    Science.gov (United States)

    Bharati, B.; Sonkar, A. K.; Singh, N.; Dash, D.; Rath, Chandana

    2017-08-01

    As TiO2 is one of the most popular photocatalysts, we have studied here the photocatalytic degradation of the most common dyestuffs like rhodamine B (RhB), congo red (CR) and methylene blue (MB), which mainly come from the textile and photographic industries using nanoparticles of TiO2. Nanoparticles of TiO2 synthesized through a simple and cost effective sol-gel technique crystallizes in the anatase phase, showing a band gap less than that of bulk value. Particles consisting of coherently scattered domains of size 33 nm are found to be agglomerated and polycrystalline in nature. While the degradation rates of MB, CR and RhB after irradiating with a renewable source of energy, i.e. sunlight, show 100% degradation, TiO2 irradiated with UV light of 4.8 eV shows a much slower degradation rate. To use the waste water after photocatalysis, we examine further the biocompatibile nature of the TiO2 nanoparticles by platelet interaction activity, hemolysis effect and MTT assay. It is worth mentioning here that TiO2 nanoparticles are found to be highly hemocompatible, show no platelet aggregation, and the level of intracellular ROS in human platelets does not show significant change in ROS level. We conclude that TiO2 nanoparticles constitute an excellent photocatalyst and biocompatible material, and that after photocatalytic degradation of dye effluents obtained from textile industries, purified water can be used in agriculture and domestic sectors.

  8. Nuclear microscopy as a tool in TiO2 nanoparticles bioaccumulation studies in aquatic species

    Science.gov (United States)

    Pinheiro, Teresa; Moita, Liliana; Silva, Luís; Mendonça, Elsa; Picado, Ana

    2013-07-01

    Engineered Titanium nanoparticles are used for a wide range of applications from coatings, sunscreen cosmetic additives to solar cells or water treatment agents. Inevitably environmental exposure can be expected and data on the ecotoxicological evaluation of nanoparticles are still scarce. The potential effects of nanoparticles of titanium dioxide (TiO2) on two model organisms, the water flea, Daphnia magna and the duckweed Lemna minor, were examined in semichronic toxicity tests. Daphnia and Lemna were exposed to TiO2 nanoparticles (average particle size value of 28 ± 11 nm (n = 42); concentration range, 1.4-25 mg/L) by dietary route and growth in medium containing the nanoparticles of TiO2, respectively. Both morphology and microdistribution of Ti in the individuals were examined by nuclear microscopy techniques. A significant amount of TiO2 was found accumulated in Daphnia exposed to nanoparticles. Nuclear microscopy imaging revealed that Ti was localized only in the digestive tract of the Daphnia, which displayed difficulty in eliminating the nanoparticles from their body. Daphnia showed higher mortality when exposed to higher concentrations of TiO2 (>10 mg/L). The exposure to TiO2 nanoparticles above 25 mg/L caused morphological alterations in Lemna. The roots became stiff and fronds colorless. The Ti mapping of cross-sections of roots and fronds showed that Ti was mainly deposited in the epidermis of the fronds and roots, with minor internalization. In summary, exposure of aquatic organisms to TiO2 nanoparticles may alter the physiology of these organisms at individual and population levels, posing risks to aquatic ecosystems.

  9. Nuclear microscopy as a tool in TiO2 nanoparticles bioaccumulation studies in aquatic species

    International Nuclear Information System (INIS)

    Pinheiro, Teresa; Moita, Liliana; Silva, Luís; Mendonça, Elsa; Picado, Ana

    2013-01-01

    Engineered Titanium nanoparticles are used for a wide range of applications from coatings, sunscreen cosmetic additives to solar cells or water treatment agents. Inevitably environmental exposure can be expected and data on the ecotoxicological evaluation of nanoparticles are still scarce. The potential effects of nanoparticles of titanium dioxide (TiO 2 ) on two model organisms, the water flea, Daphnia magna and the duckweed Lemna minor, were examined in semichronic toxicity tests. Daphnia and Lemna were exposed to TiO 2 nanoparticles (average particle size value of 28 ± 11 nm (n = 42); concentration range, 1.4–25 mg/L) by dietary route and growth in medium containing the nanoparticles of TiO 2 , respectively. Both morphology and microdistribution of Ti in the individuals were examined by nuclear microscopy techniques. A significant amount of TiO 2 was found accumulated in Daphnia exposed to nanoparticles. Nuclear microscopy imaging revealed that Ti was localized only in the digestive tract of the Daphnia, which displayed difficulty in eliminating the nanoparticles from their body. Daphnia showed higher mortality when exposed to higher concentrations of TiO 2 (>10 mg/L). The exposure to TiO 2 nanoparticles above 25 mg/L caused morphological alterations in Lemna. The roots became stiff and fronds colorless. The Ti mapping of cross-sections of roots and fronds showed that Ti was mainly deposited in the epidermis of the fronds and roots, with minor internalization. In summary, exposure of aquatic organisms to TiO 2 nanoparticles may alter the physiology of these organisms at individual and population levels, posing risks to aquatic ecosystems

  10. CdSe nanorod/TiO2 nanoparticle heterojunctions with enhanced solar- and visible-light photocatalytic activity

    Directory of Open Access Journals (Sweden)

    Fakher Laatar

    2017-12-01

    Full Text Available CdSe nanorods (NRs with an average length of ≈120 nm were prepared by a solvothermal process and associated to TiO2 nanoparticles (Aeroxide® P25 by annealing at 300 °C for 1 h. The content of CdSe NRs in CdSe/TiO2 composites was varied from 0.5 to 5 wt %. The CdSe/TiO2 heterostructured materials were characterized by XRD, TEM, SEM, XPS, UV–visible spectroscopy and Raman spectroscopy. TEM images and XRD patterns show that CdSe NRs with wurtzite structure are associated to TiO2 particles. The UV–visible spectra demonstrate that the narrow bandgap of CdSe NRs serves to increase the photoresponse of CdSe/TiO2 composites until ≈725 nm. The CdSe (2 wt %/TiO2 composite exhibits the highest photocatalytic activity for the degradation of rhodamine B in aqueous solution under simulated sunlight or visible light irradiation. The enhancement in photocatalytic activity likely originates from CdSe sensitization of TiO2 and the heterojunction between these materials which facilitates electron transfer from CdSe to TiO2. Due to its high stability (up to ten reuses without any significant loss in activity, the CdSe/TiO2 heterostructured catalysts show high potential for real water decontamination.

  11. Highly efficient indoor air purification using adsorption-enhanced-photocatalysis-based microporous TiO2 at short residence time.

    Science.gov (United States)

    Lv, Jinze; Zhu, Lizhong

    2013-01-01

    A short residence time is a key design parameter for the removal of organic pollutants in catalyst-based indoor air purification systems. In this study, we synthesized a series of TiO2 with different micropore volumes and studied their removal efficiency of indoor carbonyl pollutants at a short residence time. Our results indicated that the superior adsorption capability of TiO2 with micropores improved its performance in the photocatalytic degradation of cyclohexanone, while the photocatalytic removal of the pollutant successfully kept porous TiO2 from becoming saturated. When treated with 1 mg m(-3) cyclohexanone at a relatively humidity of 18%, the adsorption amount on microporous TiO2 was 5.4-7.9 times higher than that on P25. Removal efficiency via photocatalysis followed'the same order as the adsorption amount: TiO2-5 > TiO2-20 > TiO2-60 > TiO2-180 > P25. The advantage of microporous TiO2 over P25 became more pronounced when the residence time declined from 0.072 to 0.036 s. Moreover, as the concentration of cyclohexanone deceased from 1000 ppb to 500 ppb, removal efficiency by microporous TiO2 increased more rapidly than P25.

  12. Correlation of Photocatalysis and Photoluminescence Effect in Relation to the Surface Properties of TiO2:Tb Thin Films

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    Damian Wojcieszak

    2013-01-01

    Full Text Available In this paper structural, optical, photoluminescence, and photocatalytic properties of TiO2 and TiO2:(2.6 at. % Tb thin films have been compared. Thin films were prepared by high-energy reactive magnetron sputtering process, which enables obtaining highly nanocrystalline rutile structure of deposited films. Crystallites sizes were 8.7 nm and 6.6 nm for TiO2 and TiO2:Tb, respectively. Surface of prepared thin films was homogenous with small roughness of ca. 7.2 and 2.1 nm in case of TiO2 and TiO2:Tb samples, respectively. Optical properties measurements have shown that the incorporation of Tb into TiO2 matrix has not changed significantly the thin films transparency. It also enables obtaining photoluminescence effect in wide range from 350 to 800 nm, what is unique phenomenon in case of TiO2 with rutile structure. Moreover, it has been found that the incorporation of 2.6 at. % of Tb has increased the photocatalytic activity more than two times as compared to undoped TiO2. Additionally, for the first time in the current state of the art, the relationship between photoluminescence effect, photocatalytic activity, and surface properties of TiO2:Tb thin films has been theoretically explained.

  13. STRUKTUR MORFOLOGI, KOMPOSISI KIMIA DAN RESISTANSI LAPISAN TIO2-CU SEBAGAI LAPISAN AKTIF PADA SEL SURYA FOTOELEKTROKIMIA

    Directory of Open Access Journals (Sweden)

    Rita Prasetyowati

    2013-11-01

    Full Text Available Peningkatan efisiensi sel surya titania terus dikembangkan. Salah satunya adalah memodifikasi titania yang berfungsi sebagai lapisan aktif. Lapisan titania dapat disisipi dengan logam Cu. Penyisipan logam Cu pada TiO2 dilakukan melalui pembuatan nanokomposit TiO2-Cu dengan metode sol-gel. Lapisan TiO2-Cu yang terbentuk dikarakterisasi dengan SEM (Scanning Electron Microscopy untuk mengetahui struktur morfologi permukaan, EDX (Energy dispersive X-ray spectroscopy untuk mengetahui komposisi bahan. Sedangkan resistansi lapisan diukur menggunakan Jembatan Wheatstone. Berdasarkan hasil SEM dapat ditunjukkan bahwa struktur morfologi permukaan lapisan TiO2-Cu tidak berbeda secara signifikan dengan lapisan TiO2, yaitu cukup homogen dan memiliki ukuran butir (grain yang hampir sama. Tetapi dari hasil EDX diperoleh bahwa lapisan TiO2-Cu yaitu lapisan TiO2 yang disisipi logam tembaga mengandung  unsur Ti sebanyak 59,8%, unsur O sebanyak 40,02% dan unsur Cu sebanyak 0,19%. Sedangkan lapisan TiO2 saja mengandung unsur Ti sebanyak 54,25% dan unsur O sebanyak 45,75%. Penyisipan logam tembaga pada lapisan titania dapat menurunkan resistansi listrik lapisan. Nilai resistansi lapisan TiO2 adalah 7,714 kilo ohm. Sedangkan nilai resistansi lapisan TiO2-Cu adalah 6,624 kilo ohm.

  14. Photocatalytic Oxidation of Acetone Over High Thermally Stable TiO2 Nanosheets With Exposed (001) Facets.

    Science.gov (United States)

    Shi, Ting; Duan, Youyu; Lv, Kangle; Hu, Zhao; Li, Qin; Li, Mei; Li, Xiaofang

    2018-01-01

    Anatase TiO 2 (A-TiO 2 ) usually exhibits superior photocatalytic activity than rutile TiO 2 (R-TiO 2 ). However, the phase transformation from A-TiO 2 to R-TiO 2 will inevitably happens when the calcination temperature is up to 600°C, which hampers the practical applications of TiO 2 photocatalysis in hyperthermal situations. In this paper, high energy faceted TiO 2 nanosheets (TiO 2 -NSs) with super thermal stability was prepared by calcination of TiOF 2 cubes. With increase in the calcination temperature from 300 to 600°C, TiOF 2 transforms into TiO 2 hollow nanoboxes (TiO 2 -HNBs) assembly from TiO 2 -NSs via Ostwald Rippening process. Almost all of the TiO 2 -HNBs are disassembled into discrete TiO 2 -NSs when calcination temperature is higher than 700°C. Phase transformation from A-TiO 2 to R-TiO 2 begins at 1000°C. Only when the calcination temperature is higher than 1200°C can all the TiO 2 -NSs transforms into R-TiO 2 . The 500°C-calcined sample (T500) exhibits the highest photoreactivity toward acetone oxidation possibly because of the production of high energy TiO 2 -NSs with exposed high energy (001) facets and the surface adsorbed fluorine. Surface oxygen vacancy, due to the heat-induced removal of surface adsorbed fluoride ions, is responsible for the high thermal stability of TiO 2 -NSs which are prepared by calcination of TiOF 2 cubes.

  15. The design, fabrication, and photocatalytic utility of nanostructured semiconductors: focus on TiO2-based nanostructures

    Science.gov (United States)

    Banerjee, Arghya Narayan

    2011-01-01

    Recent advances in basic fabrication techniques of TiO2-based nanomaterials such as nanoparticles, nanowires, nanoplatelets, and both physical- and solution-based techniques have been adopted by various research groups around the world. Our research focus has been mainly on various deposition parameters used for fabricating nanostructured materials, including TiO2-organic/inorganic nanocomposite materials. Technically, TiO2 shows relatively high reactivity under ultraviolet light, the energy of which exceeds the band gap of TiO2. The development of photocatalysts exhibiting high reactivity under visible light allows the main part of the solar spectrum to be used. Visible light-activated TiO2 could be prepared by doping or sensitizing. As far as doping of TiO2 is concerned, in obtaining tailored material with improved properties, metal and nonmetal doping has been performed in the context of improved photoactivity. Nonmetal doping seems to be more promising than metal doping. TiO2 represents an effective photocatalyst for water and air purification and for self-cleaning surfaces. Additionally, it can be used as an antibacterial agent because of its strong oxidation activity and superhydrophilicity. Therefore, applications of TiO2 in terms of photocatalytic activities are discussed here. The basic mechanisms of the photoactivities of TiO2 and nanostructures are considered alongside band structure engineering and surface modification in nanostructured TiO2 in the context of doping. The article reviews the basic structural, optical, and electrical properties of TiO2, followed by detailed fabrication techniques of 0-, 1-, and quasi-2-dimensional TiO2 nanomaterials. Applications and future directions of nanostructured TiO2 are considered in the context of various photoinduced phenomena such as hydrogen production, electricity generation via dye-sensitized solar cells, photokilling and self-cleaning effect, photo-oxidation of organic pollutant, wastewater management, and organic synthesis. PMID:24198485

  16. Interaction of TiO2 nanoparticles with the marine microalga Nitzschia closterium: Growth inhibition, oxidative stress and internalization

    International Nuclear Information System (INIS)

    Xia, Bin; Chen, Bijuan; Sun, Xuemei; Qu, Keming; Ma, Feifei; Du, Meirong

    2015-01-01

    The toxicity of TiO 2 engineered nanoparticles (NPs) to the marine microalga Nitzschia closterium was investigated by examining growth inhibition, oxidative stress and uptake. The results indicated that the toxicity of TiO 2 particles to algal cells significantly increased with decreasing nominal particle size, which was evidenced by the 96 EC 50 values of 88.78, 118.80 and 179.05 mg/L for 21 nm, 60 nm and 400 nm TiO 2 particles, respectively. The growth rate was significantly inhibited when the alga was exposed to 5 mg/L TiO 2 NPs (21 nm). Measurements of antioxidant enzyme activities showed that superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activities were first induced and subsequently inhibited following exposure to 5 mg/L TiO 2 NPs. The depletion of antioxidant enzymes with a concomitant increase in malondialdehyde (MDA) levels and reactive oxygen species (ROS) posed a hazard to membrane integrity. A combination of flow cytometry analysis, transmission electron microscopy and Ti content measurement indicated that TiO 2 NPs were internalized in N. closterium cells. The level of extracellular ROS, which was induced by TiO 2 NPs under visible light, was negligible when compared with the intracellular ROS level (accounting for less than 6.0% of the total ROS level). These findings suggest that elevated TiO 2 nanotoxicity in marine environments is related to increased ROS levels caused by internalization of TiO 2 NPs. - Highlights: • Inhibition of marine microalgae by TiO 2 NPs and bulk particles was evaluated. • Aggregation of TiO 2 NPs and bulk particles was observed in marine algal test medium. • TiO 2 NPs induced damage to algal cell membranes as detected by flow cytometry. • Increased TiO 2 nanotoxicity to algal cells was caused by internalization of NPs

  17. Correlation between photoelectrochemical behaviour and photoelectrocatalytic activity and scaling-up of P25-TiO2 electrodes

    International Nuclear Information System (INIS)

    Pablos, Cristina; Marugán, Javier; Grieken, Rafael van; Adán, Cristina; Riquelme, Ainhoa; Palma, Jesús

    2014-01-01

    The use of TiO 2 electrodes may solve the two main drawbacks of photocatalytic processes: i) the necessity of recovering the catalyst and ii) the low quantum yield in the use of the radiation. This work focuses on the correlation between the photoelectrochemical properties of TiO 2 electrodes and their activity for the photoelectrocatalytic oxidation of methanol. Particulate TiO 2 electrodes prepared by deposition of P25-TiO 2 nanoparticles on titanium (TiO 2 /Ti) or conductive glass support (TiO 2 /ITO) seem to be effective for charge carrier transference on TiO 2 surface favouring the formation of ·OH radicals and consequently, the oxidation of molecules. In contrast, thermal TiO 2 electrodes prepared by annealing of titanium (Ti) present better properties for charge carrier separation as a consequence of the application of a potential bias. Despite reducing charge carrier recombination by applying an electric potential bias, the activity of thermal electrodes remains lower than that of P25-particulate electrodes. TiO 2 structure of P25-particulate electrodes does not completely allow developing a potential gradient. However, their adequate TiO 2 layer characteristics for charge carrier transfer lead to a reduction in charge carrier recombination making up for the lack of charge carrier separation when applying an electric potential bias. TiO 2 /Ti showed the highest values of activity. Therefore, the combination of the suitable TiO 2 surface properties for charge carrier transfer with an adequate conductive support seems to increase the properties of the electrode for allowing charge carrier separation. The scaling-up calculations for a TiO 2 /ITO electrode do lead to good estimations of the activity and photocurrent of larger electrodes since this photoanode made from ITO as conductive support does not seem to be significantly affected by the applied potential bias

  18. Structural and electrical properties of TiO2/ZnO core–shell nanoparticles synthesized by hydrothermal method

    International Nuclear Information System (INIS)

    Vlazan, P.; Ursu, D.H.; Irina-Moisescu, C.; Miron, I.; Sfirloaga, P.; Rusu, E.

    2015-01-01

    TiO 2 /ZnO core–shell nanoparticles were successfully synthesized by hydrothermal method in two stages: first stage is the hydrothermal synthesis of ZnO nanoparticles and second stage the obtained ZnO nanoparticles are encapsulated in TiO 2 . The obtained ZnO, TiO 2 and TiO 2 /ZnO core–shell nanoparticles were investigated by means of X-ray diffraction, transmission electron microscopy, Brunauer, Emmett, Teller and resistance measurements. X-ray diffraction analysis revealed the presence of both, TiO 2 and ZnO phases in TiO 2 /ZnO core–shell nanoparticles. According to transmission electron microscopy images, ZnO nanoparticles have hexagonal shapes, TiO 2 nanoparticles have a spherical shape, and TiO 2 /ZnO core–shell nanoparticles present agglomerates and the shape of particles is not well defined. The activation energy of TiO 2 /ZnO core–shell nanoparticles was about 101 meV. - Graphical abstract: Display Omitted - Highlights: • TiO 2 /ZnO core–shell nanoparticles were synthesized by hydrothermal method. • TiO 2 /ZnO core–shell nanoparticles were investigated by means of XRD, TEM and BET. • Electrical properties of TiO 2 /ZnO core–shell nanoparticles were investigated. • The activation energy of TiO 2 /ZnO core–shell nanoparticles was about E a = 101 meV

  19. PHOTODEGRADATION OF ALIZARIN S DYE USING TiO2-ZEOLITE AND UV RADIATION

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    Karna Wijaya

    2010-06-01

    Full Text Available An investigation of Alizarin S photodegradation using TiO2-zeolite and UV radiation was performed. TiO2-zeolite was prepared by dispersing oligocations of titanium into suspension of zeolite. The suspension was stirred and then filtered to separate the solid phase from the filtrate. the solid phase was calcined by microwave oven at 800 Watt for 5 minutes to convert the oligocations into its oxide forms. The calcined product and unmodified zeolite were characterized using x-ray diffractometry, FT-IR spectrophotometry, X-ray fluorescence and gas sorption analysis methods to determine their physicochemical properties. Photocatalytic activity of TiO2-zeolite was tested on Alizarin S solution using following method: 50 mg of zeolite was dispersed into 25 mL of 10-4 M Alizarin S. The dispersion was irradiated using 365 nm UV light at room temperature on various irradiation times, i.e. 10, 20, 30, 40 and 60 minutes. At certain irradiation time, the dispersion was filtered and the filtrate was then analyzed its concentration using UV-Vis spectrophotometry method. Characterization results exhibited that the formation of TiO2 on internal as well as external surfaces of zeolite could not be detected  with x-ray diffractometry and FT-IR spectrophotometry, however determination of titanium using x-ray fluorescence analysis on the calcined product showed that the concentration of titanium was much higher than zeolite (0.22% on zeolite and 12.08% on TiO2-zeolite. Gas sorption analysis result indicated that the the calcination  resulted in the increase of specific surface area (16,31 m2/g on zeolite and 100.96 m2/g on TiO2-zeolite as well as total pore volume of calcined product (13.34 mL/Å/g on zeolite and 57.54 mL/Å/g on TiO2-zeolite. The result of photocatalytic activitiy study showed that ca 99 % of Alizarin S was degraded by TiO2-zeolite after UV irradiation for 60 min.   Keywords: TiO2-zeolite, photocatalytic, Alizarin S.

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

    Science.gov (United States)

    Guan, Dongsheng; Cai, Chuan; Wang, Ying

    2011-04-01

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

  1. Evaluation of the content of TiO2 nanoparticles in the coatings of chewing gums.

    Science.gov (United States)

    Dudefoi, William; Terrisse, Hélène; Popa, Aurelian Florin; Gautron, Eric; Humbert, Bernard; Ropers, Marie-Hélène

    2018-02-01

    Titanium dioxide is a metal oxide used as a white pigment in many food categories, including confectionery. Due to differences in the mass fraction of nanoparticles contained in TiO 2 , the estimated intakes of TiO 2 nanoparticles differ by a factor of 10 in the literature. To resolve this problem, a better estimation of the mass of nanoparticles present in food products is needed. In this study, we focused our efforts on chewing gum, which is one of the food products contributing most to the intake of TiO 2 . The coatings of four kinds of chewing gum, where the presence of TiO 2 was confirmed by Raman spectroscopy, were extracted in aqueous phases. The extracts were analysed by transmission electron microscopy (TEM), X-ray diffraction, Fourier Transform Raman spectroscopy, and inductively coupled plasma atomic emission spectroscopy (ICP-AES) to establish their chemical composition, crystallinity and size distribution. The coatings of the four chewing gums differ chemically from each other, and more specifically the amount of TiO 2 varies from one coating to another. TiO 2 particles constitute the entire coating of some chewing gums, whereas for others, TiO 2 particles are embedded in an organic matrix and/or mixed with minerals like calcium carbonate, talc, or magnesium silicate. We found 1.1 ± 0.3 to 17.3 ± 0.9 mg TiO 2 particles per piece of chewing gum, with a mean diameter of 135 ± 42 nm. TiO 2 nanoparticles account for 19 ± 4% of all particles, which represents a mass fraction of 4.2 ± 0.1% on average. The intake of nanoparticles is thus highly dependent on the kind of chewing gum, with an estimated range extending from 0.04 ± 0.01 to 0.81 ± 0.04 mg of nano-TiO 2 per piece of chewing gum. These data should serve to refine the exposure scenario.

  2. Preparation of flexible TiO2 photoelectrodes for dye-sensitized solar cells

    Science.gov (United States)

    Li, Wen-Ren; Wang, Hsiu-Hsuan; Lin, Chia-Feng; Su, Chaochin

    2014-09-01

    Dye-sensitized solar cells (DSSCs) based on nanocrystalline TiO2 photoelectrodes on indium tin oxide (ITO) coated polymer substrates have drawn great attention due to its lightweight, flexibility and advantages in commercial applications. However, the thermal instability of polymer substrates limits the process temperature to below 150 °C. In order to assure high and firm interparticle connection between TiO2 nanocrystals (TiO2-NC) and polymer substrates, the post-treatment of flexible TiO2 photoelectrodes (F-TiO2-PE) by mechanical compression was employed. In this work, Degussa P25 TiO2-NC was mixed with tert-butyl alcohol and DI-water to form TiO2 paste. F-TiO2-PE was then prepared by coating the TiO2 paste onto ITO coated polyethylene terephthalate (PET) substrate using doctor blade followed by low temperature sintering at 120 °C for 2 hours. To study the effect of mechanical compression, we applied 50 and 100 kg/cm2 pressure on TiO2/PET to complete the fabrication of F-TiO2-PE. The surface morphology of F-TiO2-PE was characterized using scanning electron microscopy. The resultant F-TiO2-PE sample exhibited a smooth, crack-free structure indicating the great improvement in the interparticle connection of TiO2-NC. Increase of compression pressure could lead to the increase of DSSC photoconversion efficiency. The best photoconversion efficiency of 4.19 % (open circuit voltage (Voc) = 0.79 V, short-circuit photocurrent density (Jsc) = 7.75 mA/cm2, fill factor (FF) = 0.68) was obtained for the F-TiO2-PE device, which showed great enhancement compared with the F-TiO2-PE cell without compression treatment. The effect of compression in DSSC performance was vindicated by the electrochemical impedance spectroscopy measurement.

  3. Single-walled carbon nanotube-facilitated dispersion of particulate TiO2 on ZrO2 ceramic membrane filters.

    Science.gov (United States)

    Yao, Yuan; Li, Gonghu; Gray, Kimberly A; Lueptow, Richard M

    2008-07-15

    We report that SWCNTs substantially improve the uniformity and coverage of TiO2 coatings on porous ZrO2 ceramic membrane filters. The ZrO2 filters were dip coated with 100 nm anatase TiO2, TiO2/SWCNT composites, a TiO2+SWCNT mixture, and a TiO2/MWCNT composite at pH 3, 5, and 8. Whereas the TiO2+SWCNT mixture and the TiO2/MWCNT composite promote better coverage and less clumping than TiO2 alone, the TiO2/SWCNT composite forms a complete uniform coating without cracking at pH 5 ( approximately 100% coverage). A combination of chemical and electrostatic effects between TiO2 and SWCNTs forming the composite as well as between the composite and the ZrO2 surface explains these observations.

  4. Photocatalytic activity of TiO2/Nb2O5/PANI and TiO2/Nb2O5/RGO as new nanocomposites for degradation of organic pollutants.

    Science.gov (United States)

    Zarrin, Saviz; Heshmatpour, Felora

    2018-06-05

    In this study, highly active titanium dioxide modified by niobium oxide (Nb 2 O 5 ), polymer (PANI) and reduced graphene oxide (RGO) were successfully prepared. The morphology, structure, surface area and light absorption properties of the present nanocomposites for removal of methylene blue (MB) and methyl orange (MO) were investigated and compared with those of TiO 2 /Nb 2 O 5 and TiO 2 nanoparticles. The characterization techniques such as XRD, FT-IR, UV-vis, SEM, EDX, BET and TEM were employed in order to identify the nanocomposites. Also, photocatalytic properties of TiO 2 /Nb 2 O 5 /PANI and TiO 2 /Nb 2 O 5 /RGO nanocomposites under visible light irradiation were studied. In this way, the obtained results were compared to each other and also compared to TiO 2 /Nb 2 O 5 and TiO 2 nanoparticles. In this context, the chemical oxygen demand (COD) removal follows the photodegradation in observed performance. The results indicate that reduced TiO 2 /Nb 2 O 5 nanocomposite is effectively modified by graphene oxide to give TiO 2 /Nb 2 O 5 /RGO composite. The TiO 2 /Nb 2 O 5 /RGO exhibits significantly higher photocatalytic activity in degradation of organic dyes under visible light rather than that of TiO 2 /Nb 2 O 5 /PANI, TiO 2 /Nb 2 O 5 and pure TiO 2 . Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Synthesis and Photocatalytic Activity of Mo-Doped TiO2 Nanoparticles

    Directory of Open Access Journals (Sweden)

    Ji-guo Huang

    2015-01-01

    Full Text Available The undoped and Mo-doped TiO2 nanoparticles were synthesized by sol-gel method. The as-prepared samples were characterized by X-ray diffraction (XRD, diffuse reflectance UV-visible absorption spectra (UV-vis DRS, X-ray photoelectron spectra (XPS, and transmission electron microscopy (TEM. The photocatalytic activity was evaluated by photocatalytic degradation of methylene blue under irradiation of a 500 W xenon lamp and natural solar light outdoor. Effects of calcination temperatures and Mo doping amounts on crystal phase, crystallite size, lattice distortion, and optical properties were investigated. The results showed that most of Mo6+ took the place of Ti4+ in the crystal lattice of TiO2, which inhibited the growth of crystallite size, suppressed the transformation from anatase to rutile, and led to lattice distortion of TiO2. Mo doping narrowed the band gap (from 3.05 eV of TiO2 to 2.73 eV of TiMo0.02O and efficiently increased the optical absorption in visible region. Mo doping was shown to be an efficient method for degradation of methylene blue under visible light, especially under solar light. When the calcination temperature was 550°C and the Mo doping amount was 2.0%, the Mo-doped TiO2 sample exhibited the highest photocatalytic activity.

  6. Decolorization of Methylene Blue with TiO2 Sol via UV Irradiation Photocatalytic Degradation

    Directory of Open Access Journals (Sweden)

    Jun Yao

    2010-01-01

    Full Text Available TiO2 sol was prepared for the degradation of methylene blue (MB solution under ultraviolet (UV irradiation. The absorption spectra of MB indicated that the maximum wavelength, 663 nm, almost kept the same. The performance of 92.3% for color removal was reached after 160 min. The particle size of TiO2 sol was about 22.5 nm. X-ray diffraction showed that TiO2 consisted of a single anatase phase. The small size and anatase phase probably resulted in high photocatalytic activity of TiO2 sol. The degradation ratio decreased as the initial concentration of MB increased. The photodegradation efficiency decreased in the order of pH 2>pH 9>pH 7. Regarding catalyst load, the degradation increased with the mass of catalyst up to an amount of 1.5 g⋅L−1 then decreased as the mass continued to increase. The addition of H2O2 to TiO2 sol resulted in an increase on the degradation ratio.

  7. Highly stable colloidal TiO2 nanocrystals with strong violet-blue emission

    International Nuclear Information System (INIS)

    Ghamsari, Morteza Sasani; Gaeeni, Mohammad Reza; Han, Wooje; Park, Hyung-Ho

    2016-01-01

    Improved sol–gel method has been applied to prepare highly stable colloidal TiO 2 nanocrystals. The synthesized titania nanocrystals exhibit strong emission in the violet-blue wavelength region. Very long evolution time was obtained by preventing the sol to gel conversion with reflux process. FTIR, XRD, UV–vis absorption, photoluminescence and high resolution transmission electron microscope (HRTEM) were used to study the optical properties, crystalline phase, morphology, shape and size of prepared TiO 2 colloidal nanocrystals. HRTEM showed that the diameter of TiO 2 colloidal nanocrystals is about 5 nm. Although the PL spectra show similar spectral features upon excitation wavelengths at 280, 300 and 350 nm, but their emission intensities are significantly different from each other. Photoluminescence quantum yield for TiO 2 colloidal nanocrystals is estimated to be 49% with 280 nm excitation wavelength which is in agreement and better than reported before. Obtained results confirm that the prepared colloidal TiO 2 sample has enough potential for optoelectronics applications.

  8. Fabrication of TiO2 Nanotanks Embedded in a Nanoporous Alumina Template

    Directory of Open Access Journals (Sweden)

    C. Massard

    2015-01-01

    Full Text Available The feasibility of surface nanopatterning with TiO2 nanotanks embedded in a nanoporous alumina template was investigated. Self-assembled anodized aluminium oxide (AAO template, in conjunction with sol gel process, was used to fabricate this nanocomposite object. Through hydrolysis and condensation of the titanium alkoxide, an inorganic TiO2 gel was moulded within the nanopore cavities of the alumina template. The nanocomposite object underwent two thermal treatments to stabilize and crystallize the TiO2. The morphology of the nanocomposite object was characterized by Field Emission Scanning Electron Microscopy (FESEM. The TiO2 nanotanks obtained have cylindrical shapes and are approximately 69 nm in diameter with a tank-to-tank distance of 26 nm. X-ray diffraction analyses performed by Transmission Electron Microscopy (TEM with selected area electron diffraction (SAED were used to investigate the TiO2 structure. The optical properties were studied using UV-Vis spectroscopy.

  9. Sol-Gel TiO2 thin films sensitized with the mulberry pigment cyanidin

    Directory of Open Access Journals (Sweden)

    Emerson Henrique de Faria

    2007-12-01

    Full Text Available TiO2 films have various applications, among them solar cells and photodegradation of pollutants. In this study, we investigated TiO2 films functionalized with the organic dye cyanidin extracted from black mulberry (Morus nigra. The TiO2 was functionalized by the sol-gel method and the film was deposited on glass substrates by dip-coating. Our aim was to investigate the interaction between the semiconductor and the dye, as well as the influence of the velocity and number of deposits on the characteristics of the film. Using ultraviolet-visible spectroscopy, we observed a shift from the maximum absorption band at 545 nm for the dye’s ethanol solution to 595 nm for the film, indicating interaction of the cyanidin with the TiO2. The absorption spectra in the infrared region of the functionalized TiO2 particles showed bands characteristic of the oxide and indicated their interaction with the dye. Using profilometry and m-line techniques, we found that the films presented thicknesses in the order of 100 nm. A SEM analysis confirmed the high density of the films.

  10. Enhanced Photocatalytic Activity of TiO2 Nanoparticles Supported on Electrically Polarized Hydroxyapatite.

    Science.gov (United States)

    Zhang, Xuefei; Yates, Matthew Z

    2018-05-23

    Fast recombination of photogenerated charge carriers in titanium dioxide (TiO 2 ) remains a challenging issue, limiting the photocatalytic activity. This study demonstrates increased photocatalytic performance of TiO 2 nanoparticles supported on electrically polarized hydroxyapatite (HA) films. Dense and thermally stable yttrium and fluorine co-doped HA films with giant internal polarization were synthesized as photocatalyst supports. TiO 2 nanoparticles deposited on the support were then used to catalyze the photochemical reduction of aqueous silver ions to produce silver nanoparticles. It was found that significantly more silver nanoparticles were produced on polarized HA supports than on depolarized HA supports. In addition, the photodegradation of methyl orange with TiO 2 nanoparticles on polarized HA supports was found to be much faster than with TiO 2 nanoparticles on depolarized HA supports. It is proposed that separation of photogenerated electrons and holes in TiO nanoparticles is promoted by the internal polarization of the HA support, and consequently, the recombination of charge carriers is mitigated. The results imply that materials with large internal polarization can be used in strategies for enhancing quantum efficiency of photocatalysts.

  11. Efficient silver modification of TiO2 nanotubes with enhanced photocatalytic activity

    Science.gov (United States)

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

    2018-06-01

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

  12. Application of a TiO2 nanocomposite in earplugs, a case study of noise reduction.

    Science.gov (United States)

    Ibrahimi Ghavamabadi, Leila; Fouladi Dehaghi, Behzad; Hesampour, Morteza; Ahmadi Angali, Kambiz

    2018-03-13

    Use of hearing protection devices (HPDs) has become necessary when other control measures cannot reduce noise to a safe and standard level. In most countries, more effective hearing protection devices are in demand. The aim of this study was to examine the effects of titanium dioxide (TiO 2 ) nanoparticles on noise reduction efficiency in a polyvinyl chloride (PVC) earplug. An S-60 type PVC polymer as main matrix and TiO 2 with 30 nm size were used. PVC/TiO 2 nanocomposite was mixed at a temperature of 160 °C and 40 rounds per minute (rpm) and the samples were prepared with 0, 0.2 and 0.5 wt% of TiO 2 nanoparticle concentrations. Earplug samples with PVC/TiO 2 (0.2, 0.5 wt%) nanoparticles, when compared with raw earplugs, showed almost equal noise attenuation at low frequencies (500- 125 Hz). However, at high frequencies (2-8 kHz), the power of noise reduction of earplugs containing TiO 2 nanoparticles was significantly increased. The results of the present study showed that samples containing nanoparticles of TiO 2 had more noticeable noise reduction abilities at higher frequencies in comparison with samples without the nanoparticles.

  13. Self-assembled supramolecular system PDINH on TiO2 surface enhances hydrogen production.

    Science.gov (United States)

    Li, Xin; Lv, Xingshuai; Zhang, Qianqian; Huang, Baibiao; Wang, Peng; Qin, Xiaoyan; Zhang, Xiaoyang; Dai, Ying

    2018-09-01

    Constructing organic-inorganic hybrids is one of the hopeful strategies to improve photocatalyst performance. In this study, perylene-3,4,9,10-tetracarboxylic diimide (PDINH) and commercial TiO 2 P25 are chosen as raw materials to construct a PDINH/TiO 2 organic-inorganic hybrid, which has higher photocatalytic H 2 production activity and photocurrent intensity than pure PDINH and TiO 2 , respectively. The apparent quantum efficiency for H 2 production over 0.5%PDINH/TiO 2 reaches as high as 70.69% using irradiation at 365 nm. Moreover, XRD, DRS, HRTEM, FT-IR, and XPS are used to characterize the crystal structure, optical absorption, morphology, molecular structure, and chemical bonds, as well as the elemental and chemical states of PDINH/TiO 2 organic-inorganic hybrid. The interfaces between PDINH and TiO 2 , which largely determine photocatalytic performance, is also analyzed systematically. Furthermore, charge density difference (Δρ) is used to analyze the electron-ion interactions of PDINH and TiO 2 , and reveals that substantial charge transfer occurs from PDINH to TiO 2 . Copyright © 2018. Published by Elsevier Inc.

  14. Significantly enhanced visible light response in single TiO2 nanowire by nitrogen ion implantation

    Science.gov (United States)

    Wu, Pengcheng; Song, Xianyin; Si, Shuyao; Ke, Zunjian; Cheng, Li; Li, Wenqing; Xiao, Xiangheng; Jiang, Changzhong

    2018-05-01

    The metal-oxide semiconductor TiO2 shows enormous potential in the field of photoelectric detection; however, UV-light absorption only restricts its widespread application. It is considered that nitrogen doping can improve the visible light absorption of TiO2, but the effect of traditional chemical doping is far from being used for visible light detection. Herein, we dramatically broadened the absorption spectrum of the TiO2 nanowire (NW) by nitrogen ion implantation and apply the N-doped single TiO2 NW to visible light detection for the first time. Moreover, this novel strategy effectively modifies the surface states and thus regulates the height of Schottky barriers at the metal/semiconductor interface, which is crucial to realizing high responsivity and a fast response rate. Under the illumination of a laser with a wavelength of 457 nm, our fabricated photodetector exhibits favorable responsivity (8 A W-1) and a short response time (0.5 s). These results indicate that ion implantation is a promising method in exploring the visible light detection of TiO2.

  15. Tailoring luminescence properties of TiO2 nanoparticles by Mn doping

    International Nuclear Information System (INIS)

    Choudhury, B.; Choudhury, A.

    2013-01-01

    TiO 2 nanoparticles are doped with three different concentrations of Mn, 2%, 4% and 6% respectively. Absorption edge of TiO 2 is shifted from UV to visible region on amplification of Mn content. Room temperature photoluminescence spectra, excited at 320 nm, exhibit band edge and visible emission peaks associated with self trapped excitons, oxygen defects, etc. Doping of Mn increases the width and decreases the intensity of the UV emission peak. Potential fluctuations of impurities increase the width and auger type non-radiative recombination decreases the intensity of the UV emission peak. The intensity ratio of the UV to defect emission band decreases on doping, indicating degradation of structural quality. Excitation of pure and doped nanoparticles at 390 nm results in Mn 2+ emission peaks at 525 nm and 585 nm respectively. Photoluminescence excitation spectra also indicate the presence of Mn 2+ in the crystalline environment of TiO 2 . The oxygen defects and Mn related impurities act as efficient trap centers and increases the lifetime of the charge carriers. -- Highlights: ► Doping of Mn increases the d-spacing of TiO 2 nanoparticles. ► Characteristic d–d electronic transition of Mn 2+ is observed in the absorption spectra. ► Doping of Mn quenches the UV and visible emission peaks of TiO 2 . ► Photoexcitation at 390 nm generates emission peaks of Mn 2+

  16. Soft-Template Synthesis of Mesoporous Anatase TiO2 Nanospheres and Its Enhanced Photoactivity

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    Xiaojia Li

    2017-11-01

    Full Text Available Highly crystalline mesoporous anatase TiO2 nanospheres with high surface area (higher than P25 and anatase TiO2 are prepared by a soft-template method. Despite the high specific surface area, these samples have three times lower equilibrium adsorption (<2% than Degussa P25. The rate constant of the mesoporous anatase TiO2 (0.024 min−1 reported here is 364% higher than that of P25 (0.0066 min−1, for the same catalytic loading. The results of oxidation-extraction photometry using several reactive oxygen species (ROS scavengers indicated that mesoporous anatase TiO2 generates more ROS than P25 under UV-light irradiation. This significant improvement in the photocatalytic performance of mesoporous spherical TiO2 arises from the following synergistic effects in the reported sample: (i high surface area; (ii improved crystallinity; (iii narrow pore wall thicknesses (ensuring the rapid migration of photogenerated carriers to the surface of the material; and (iv greater ROS generation under UV-light.

  17. First-principles study of Mn-S codoped anatase TiO2

    Science.gov (United States)

    Li, Senlin; Huang, Jinliang; Ning, Xiangmei; Chen, Yongcha; Shi, Qingkui

    2018-04-01

    In this work, the CASTEP program in Materials Studio 2017 software package was applied to calculate the electronic structures and optical properties of pure anatase TiO2, S-doped, Mn-doped and Mn-S co-doped anatase TiO2 by GGA + U methods based on the density function theory (DFT). The results indicate that the lattice is distorted and the lattice constant is reduce due to doping. The doping also introduces impurity energy levels into the forbidden band. After substitution of Mn for Ti atom, band gap narrowing of anatase TiO2 is caused by the impurity energy levels appearance in the near Fermi surface, which are contributed by Mn-3d orbital, Ti-3d orbital and O-2p orbital hybridization. After substitution of S for O atom, band gap narrowing is creited with the shallow accepter level under the conduction hand of S-3p orbital. The Mn-S co-doped anatase TiO2 could be a potential candidate for a photocatalyst because of tis enhanced absorption ability of visible light. The results can well explain the immanent cause of a band gap narrowing as well as a red shift in the spectrum for doped anatase TiO2.

  18. Density functional theory studies of TiO2 for photocatalysis and Li storage applications

    Science.gov (United States)

    Kim, Yong-Hoon; Lee, Ji Il; Lee, Dong Ki; Lee, Gyu Heon; Kang, Jeung Ku

    We present two theory-experiment collaboration studies of anatase TiO2 for energy applications. First, we discuss a hydrogen-nitrogen co-doped TiO2 (HN-TiO2) as a photocatalyst, and show that the interstitially introduced HN contributes to the increase of solar-to-fuel conversion efficiency. We find that the variation of valence band maximum (VBM) of NH-TiO2 extends the photoactive spectrum to the visible light, and argue that created mid-gap states produce efficient electron and hole conduction channels. Next, we consider experimentally fabricated hierarchical TiO2 nanocrystals integrated with binder-free porous graphene (PG) network foam for a Li storage application. It was found that the TiO2-PG facilitated rapid ionic transfer during the Li-ion insertion/extraction process. We clarify the mechanisms by showing that Li ion migration into the TiO2-PG interface stabilize the binder-free oxide-graphene interface. Atomistic mechanism of Li ion insertion and migration is discussed by comparing cases between an isolated Li ion, when the crowding effect is included, and when the surface Li ions are present. We found that the supply of additional surface Li ions significantly reduce the Li insertion barrier, driving a spontaneous domino-like concerted Li insertion at the oxide surface region.

  19. Nitrogen and europium doped TiO2 anodized films with applications in photocatalysis

    International Nuclear Information System (INIS)

    Chi, Choong-Soo; Choi, Jinwook; Jeong, Yongsoo; Lee, Oh Yeon; Oh, Han-Jun

    2011-01-01

    Micro-arc oxidation method is a useful process for mesoporous titanium dioxide films. In order to improve the photocatalytic activity of the TiO 2 film, N-Eu co-doped titania catalyst was synthesized by micro-arc oxidation in the H 2 SO 4 /Eu(NO 3 ) 3 mixture solution. The specific surface area and the roughness of the anodic titania film fabricated in the H 2 SO 4 /Eu(NO 3 ) 3 electrolyte, were increased compared to that of the anodic TiO 2 film prepared in H 2 SO 4 solution. The absorbance response of N-Eu titania film shows a higher adsorption onset toward visible light region, and the incorporated N and Eu ions during anodization as a dopant in the anodic TiO 2 film significantly enhanced the photocatalytic activity for dye degradation. After dye decomposition test for 3 h, dye removal rates for the anodic TiO 2 film were 60.7% and 90.1% for the N-Eu doped titania film. The improvement of the photocatalytic activity was ascribed to the synergistic effects of the surface enlargement and the new electronic state of the TiO 2 band gap by N and Eu co-doping.

  20. Preparation and photocatalytic activity of chemically-bonded phosphate ceramics containing TiO2

    Science.gov (United States)

    Martins, Monize Aparecida; de Lima, Bruna de Oliveira; Ferreira, Leticia Patrício; Colonetti, Emerson; Feltrin, Jucilene; De Noni, Agenor

    2017-05-01

    Titanium dioxide was incorporated into chemically-bonded phosphate ceramic for use as photocatalytic inorganic coating. The coatings obtained were applied to unglazed ceramic tiles and cured at 350 °C. The surfaces were characterized by photocatalytic activity, determined in aqueous medium, based on the degradation of methylene blue dye. The effects of the percentage of TiO2 and the thickness of the layer on the photocatalytic efficiency were evaluated. The influence of the incorporation of TiO2 on the consolidation of the phosphate matrix coating was investigated using the wear resistance test. The crystalline phases of the coatings obtained were determined by XRD. The microstructure of the surfaces was analyzed by SEM. The thermal curing treatment did not cause a phase transition from anatase to rutile. An increase in the photocatalytic activity of the coating was observed with an increase in the TiO2 content. The dye degradation indices ranged from 14.9 to 44.0%. The photocatalytic efficiency was not correlated with the thickness of the coating layer deposited. The resistance to wear decreased with an increase in the TiO2 content. Comparison with a commercial photocatalytic ceramic coating indicated that there is a range of values for the TiO2 contents which offer potential for photocatalytic applications.