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Sample records for fabricated tio2 x nx

  1. Fabrication and Photocatalytic Property of One-Dimensional SrTiO3/TiO2-xNx Nanostructures

    Directory of Open Access Journals (Sweden)

    Huarong Zhang

    2013-01-01

    Full Text Available One-dimensional SrTiO3/TiO2−xNx nanostructures were prepared by the hydrothermal method and investigated by X-ray diffraction (XRD, transmission electron microscopy (TEM, X-ray photoelectron spectroscopy (XPS, and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS measurements. The photocatalytic activities of the prepared samples were evaluated by photodegrading the methylene blue (MB solution. According to the characterizations, the intermediate product of SrTiO3/titanate nanotubes was presented after hydrothermal processing of the TiO2−xNx nanoparticles with the mixed solution of NaOH and Sr(NO32. The final product of SrTiO3/TiO2−xNx nanorods was obtained after calcining the intermediate. As compared to the TiO2−xNx nanoparticles, the absorption performance of SrTiO3/titanate nanotubes or SrTiO3/TiO2−xNx nanorods was depressed, instead of improving it. The mechanisms of the absorption property changes were discussed. The SrTiO3/TiO2−xNx nanorods presented better photocatalytic activity than the TiO2−xNx nanoparticles or nanorods. However, due to overmuch adsorption, the SrTiO3/titanate nanotubes gave ordinary photocatalytic performances.

  2. Fabrication and Photocatalytic Property of One-Dimensional SrTiO3/TiO2-xNx Nanostructures

    OpenAIRE

    Huarong Zhang; Miao Guashuai; Ma Xingping; Wang Bei

    2013-01-01

    One-dimensional SrTiO3/TiO2−xNx nanostructures were prepared by the hydrothermal method and investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) measurements. The photocatalytic activities of the prepared samples were evaluated by photodegrading the methylene blue (MB) solution. According to the characterizations, the intermediate product of SrTiO3/titanate...

  3. The comparison of visible-light photocatalytic activity for the degradation of propylene between Ag TiO2-x Nx and TiO2-x Nx%Ag/TiO2-x Nx 与 TiO2-x Nx 可见光催化降解丙烯的活性对比

    Institute of Scientific and Technical Information of China (English)

    张郴艳; 朱兆田; 彭琳珊; 马清晨; 王曼丽; 庞钰华; 何建英; 冯彩霞

    2016-01-01

    利用纳米管钛酸(NTA)和氨水的水热反应制得 TiO 2-x Nx 系列催化剂,并进一步通过热分解-机械研磨的方法在 TiO 2-x Nx 表面附着上银颗粒,制得 Ag/TiO 2-x Nx 系列催化剂。采用 X 射线衍射(XRD)、紫外-可见漫反射(DRS)、X 射线光电子能谱(XPS)等技术对催化剂进行了表征和分析。光催化氧化丙烯的实验对比了TiO 2-x Nx 与 Ag/TiO 2-x Nx 两个系列催化剂的可见光催化活性,考察了氧空位、晶型结构、氮含量和银颗粒对催化剂可见光催化活性的影响。结果表明,催化剂锐钛矿的晶型越好,氧空位含量越高,催化剂的可见光催化活性越好;贵金属银的电子捕获能力使得 Ag/TiO 2-x Nx 的可见光催化活性远高于 TiO 2-x Nx 催化剂。%TiO 2 -x Nx series of catalysts were prepared by hydrothermal reaction method using nanotubed titanic acid (denoted as NTA)and ammonia as raw materials.Furthermore,silver nanoparticles were loaded on the surface of TiO 2 -x Nx by thermal decomposition-mechanical grinding method to produce Ag/TiO 2 -x Nx photocatalysts,TiO 2 -x Nx catalysts were character-ized by X-ray diffraction (XRD),UV-Vis diffuse reflectance spectroscopy (DRS)and X-ray photoelectron spectroscopy (XPS).The visible-light activity of two series of photocatalysts, TiO 2 -x Nx and Ag/TiO 2 -x Nx ,were compared by the degradation of propylene.Some effects of oxygen vacancy,crystal structure,contents of doped nitrogen and loaded silver on the visible-light activity were also studied.Results show that the better anatase structure and the higher content of oxygen vacancy are the higher visible-light activity will be.In addition,the visible-light activity of Ag/TiO 2 -x Nx is much higher than that of TiO 2 -x Nx due to the strong trapping electron ability of noble metal silver.

  4. Compositional and Structural Properties of TiO2-xNx Thin Films Deposited by Radio-Frequency Magnetron Sputtering

    Institute of Scientific and Technical Information of China (English)

    JING Shi-Wei; LIU Yi-Chun; LIANG Yu; MA Jian-Gang; LU You-Ming; SHEN De-Zhen; ZHANG Ji-Ying; FAN Xi-Wu; MU Ri-Xiang

    2006-01-01

    @@ TiO2-xNx thin films are deposited onto Si(100) and quartz substrates by a rf magnetron sputtering method using a titanium metal disc as a target in Ar, N2, and O2 atmospheres. The substrate temperature is kept at 300°C. The O2 and Ar gas flow rates are kept to be constants and the N gas flow rate is varied. TiO2-xNx films with different N contents are characterized by x-ray diffraction and x-ray photoelectron spectroscopy. The results indicate that the TiO2-xNx thin films can be obtained at 13% N and 15% N contents in the film, and the films with mixed TiO2 and TiN crystal can be obtained at 13% N and 15% N contents in the film. In terms of the results of x-ray photoelectron spectroscopy, N 1s of β-N (396 eV) is the main component in the TiO2-xNx thin films.

  5. Study of concentration-dependent cobalt ion doping of TiO2 and TiO(2-x)Nx at the nanoscale.

    Science.gov (United States)

    Gole, James L; Prokes, Sharka M; Glembocki, O J; Wang, Junwei; Qiu, Xiaofeng; Burda, Clemens

    2010-07-01

    Experiments with a porous sol-gel generated TiO(2) nanocolloid and its corresponding oxynitride TiO(2-x)N(x) are carried out to evaluate those transformations which accompany additional doping with transition metals. In this study, doping with cobalt (Co(ii)) ions is evaluated using a combination of core level and VB-photoelectron and optical spectroscopy, complementing data obtained from Raman spectroscopy. Raman spectroscopy suggests that cobalt doping of porous sol-gel generated anatase TiO(2) and nitridated TiO(2-x)N(x) introduces a spinel-like structure into the TiO(2) and TiO(2-x)N(x) lattices. TEM and XPS data complemented by valence band-photoelectron spectra demonstrate that metallic cobalt clusters are not formed even at high doping levels. As evidenced by Raman spectroscopy, the creation of a spinel-like structure is commensurate with the room temperature conversion of the oxide and its oxynitride from the anatase to the rutile form. The onset of this kinetically driven process correlates with the formation of spinel sites within the TiO(2) and TiO(2-x)N(x) particles. Despite their visible light absorption, the photocatalytic activity of these cobalt seeded systems is diminished relative to the oxynitride TiO(2-x)N(x).

  6. Ti K-edge X-ray absorption spectra of spray pyrolysis synthesized TiO2-x and TiO2-x Nx thin films

    Science.gov (United States)

    Sahoo, Madhusmita; Yadav, Ashok Kumar; Jha, S. N.; Bhattacharyya, Dibyendu; Mathews, Tom; Dash, S.

    2017-05-01

    Oxygen deficient TiO2 and N-TiO2 anatase thin films were synthesized by employing a two step process. First TiO2 and N-TiO2 films were synthesized by using a cost effective spray pyrolysis method. Subsequently, these films were reduced under H2 to create oxygen vacancies. Formation of oxygen vacancies was confirmed by using synchrotron source X-ray Absorption Spectroscopy (XAS). Effect of oxygen vacancies on electronic and structural properties were deduced from the near edge and extended region analysis of the X-ray absorption spectra. It is inferred that reduction time plays a crucial role in creating oxygen vacancies and number of oxygen vacancies increases with increase in reduction time. Substrate effect was delineated by using Si and FTO (Fluorine doped tin oxide coated glass) as substrates for film deposition.

  7. Mechanistic Study of Visible-Light-Induced Photodegradation of 4-Chlorophenol by TiO2−xNx with Low Nitrogen Concentration

    Directory of Open Access Journals (Sweden)

    Guangfeng Shang

    2012-01-01

    Full Text Available TiO2−x Nx powders with low N-doping concentrations (0.021<<0.049 were prepared by annealing commercial TiO2 (P-25 under an NH3 flow at 550°C. Regardless of UV or visible case, the photoactivities of the samples decreased as x increased, and TiO1.979N0.021 showed the highest activity for the 4-chlorophenol (4-CP decomposition under the visible-light irradiation. The visible-light response for N-doped TiO2 could arise from an N-induced midgap level, formed above the valence band (O 2p. Electron spin resonance (ESR measurements and the radical scavenger technologies gave the combined evidence that the active species (•OH and O2•− are responsible for the photodecomposition of 4-CP over TiO2−xNx under the visible irradiation. A possible photocatalytic mechanism was discussed in detail.

  8. Study on bonding strength of nitrogen-doped TiO2-xNx films to orthodontic brackets%掺氮TiO2-xNx薄膜托槽粘接强度的研究

    Institute of Scientific and Technical Information of China (English)

    王璞; 曹宝成; 王婧; 曹帅; 高静; 王育华

    2012-01-01

    目的 研究掺氮TiO2-xNx薄膜托槽的制备过程对粘接强度的影响.方法 应用磁控溅射法在普通金属托槽表面制备TiO2-xNx薄膜得到掺氮TiO2-xNx薄膜托槽,将掺氮TiO2-xNx薄膜托槽通入氮气后在450℃条件下退火处理2h得到退火后掺氮TiO2-xNx薄膜托槽.通过X射线衍射观察普通金属托槽及退火前、退火后掺氮TiO2-xNx薄膜托槽表面结构,通过扫描电镜(SEM)观察3种托槽网底形貌.将60颗因正畸需要已拔除的健康前磨牙按照3种托槽和2种储存条件(室温蒸馏水、冷热循环)随机分为6组,每组10颗,使用京津釉质粘合剂按要求粘接,用电子万能材料试验机测试并记录所有托槽的剪切强度,使用SPSS 17.0统计软件处理数据,并对实验结果进行单因素方差分析.结果 掺氮TiO2-xNx薄膜托槽表面为均一的锐钛矿相结构,晶粒粒径为30 nm.3种托槽的底板网格清晰,排列整齐,无明显不同.冷热循环条件下的3种托槽粘接强度均低于室温蒸馏水保存下的托槽粘接强度(P<0.01),同一处理条件下3种托槽的粘接强度差异无统计学意义(P>0.05).结论 掺氮TiO2-xNx薄膜托槽的粘接强度没有受到制备过程的影响,能够满足临床正畸治疗需要.%Objective To evaluate the effect of preparation process on the bonding strength of the nitrogen-doped TiO2-xNx films on brackets. Methods Radio frequency magnetron sputtering was used to prepare nitrogen-doped TiO2-xNx films on the surface of stainless steel brackets. Post annealing was performed on TiC>2-x Nx films at 450'C in nitrogen atmosphere for 2 h. The structures and surface morphologies of 3 types brackets, ordinary stainless steel brackets, nitrogen-doped TiO2-xNx films on brackets before annealing and the brackets after annealing, were evaluated by X-ray diffraction. The base plate of brackets was observed by scanning electron microscopy (SEM). The three types of brackets were also divided into 2 groups

  9. Optimal levels of oxygen deficiency in the visible light photocatalyst TiO2-x and long-term stability of catalytic performance

    Science.gov (United States)

    Nakano, Takuma; Ito, Ryosuke; Kogoshi, Sumio; Katayama, Noboru

    2016-11-01

    The dependence of the visible light-responsive photocatalytic activity of oxygen deficient TiO2 (TiO2-x) prepared by Ar/H2 plasma surface treatment on the degree of oxygen deficiency (x) was assessed to determine the deficiency region associated with highest performance. The highest activity was obtained at x=0.06 (TiO1.94). The maximum visible light activity for this material, estimated from the formaldehyde (HCHO) removal rate, was three times higher than that exhibited by nitrogen-doped TiO2 (TiO2-xNx). The catalytic ability was found to decrease over the first week after fabrication of the material, after which it became stable, and the performance of TiO2-x at this point was found to be nearly equal to that of TiO2-xNx. The results of ab initio calculations of density of states for TiO2-x suggest that new oxygen deficiency states emerge at almost the exact center between the valence and conduction bands when x>0.06, which increases the recombination rate between electrons and holes. Therefore the declining performance of TiO2-x at larger x values is attributed to the emergence of new oxygen deficient states.

  10. Enhanced visible-light-driven photocatalytic activity of mesoporous TiO2-xNx derived from the ethylenediamine-based complex

    Science.gov (United States)

    Jiang, Zheng; Kong, Liang; Alenazey, Feraih Sh.; Qian, Yangdong; France, Liam; Xiao, Tiancun; Edwards, Peter P.

    2013-05-01

    A facile solvent evaporation induced self-assembly (SEISA) strategy was developed to synthesize mesoporous N-doped anatase TiO2 (SE-meso-TON) using a single organic complex precursor derived in situ from titanium butoxide and ethylenediamine in ethanol solution. After the evaporation of ethanol in a fume hood and subsequent calcinations at 450 °C, the obtained N-doped TiO2 (meso-TON) anatase was of finite crystallite size, developed porosity, large surface area (101 m2 g-1) and extended light absorption in the visible region. This SE-meso-TON also showed superior photocatalytic activity to the SG-meso-TON anatase prepared via sol-gel synthesis. On the basis of characterization results from XRD, XPS, N2 adsorption-desorption and ESR, the enhanced visible-light-responsive photocatalytic activity of SE-meso-TON was assigned to its developed mesoporosity and reduced oxygen vacancies.

  11. TiO2-xNx/硅藻土复合光催化剂的制备及其可见光催化活性%Photocatalytic Degradation of Rhodamine B with TiO2-xNx/diatomite

    Institute of Scientific and Technical Information of China (English)

    危琼辉; 沈翔; 夏勇; 柳艳

    2011-01-01

    以尿素为氮源,硅藻土为载体,用溶胶-凝胶法合成了硅藻土负载氮掺杂纳米TiO2复合光催化剂。采用XRD,UV-vis对样品进行了表征;以罗丹明B为降解对象,考察了罗丹明B初始浓度、催化剂投加量、溶液初始pH值对降解率的影响,同时考察了样品在太阳光下的光催化活性。结果表明,掺氮TiO2经450℃焙烧2 h后为锐钛矿型,N掺杂使催化剂的吸收边红移至550 nm左右,诱发TiO2可见光催化活性;当催化剂用量为2g/L,溶液初始pH值为6.5时,初始浓度为10 mg/L的罗丹明B在氙灯光照45min后降解率为100%,太阳光照160 min后降解率为97.4%。%The N doped and nano-sized TiO2 immobilized on diatomite were prepared by the sol-gel method with urea as the nitrogen source. The samples were characterized by XRD and UV-vis absorbance spectra. The photocatalytic activity of the photocatalyst was investigated using rhodamine B as the photo-degrading compound; the effects of the concentration of rhodamine B, the amount of catalyst, pH value and the photocatalytic activity under sunlight were investigated. The results indicate that crystal phase of the N-doped TiO2 sintered at 450 X, for 2 h is anatase; the absorption edge of the samples is shift to 550 nm and increase the visible-light responsive photocatalytic activity; When the initial concentration of rho-damine B is 10 mg/L, the amount of catalyst is 2 g/L and initial pH is 6.5, after irradiation with Xenon-light for 45 min, the degradation rate is 100% ; after irradiation with sunlight for 160 min, the degradation rate is 97.4%.

  12. Atomic Layer Deposition TiO2 Films and TiO2/SiNx Stacks Applied for Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Zu-Po Yang

    2016-08-01

    Full Text Available Titanium oxide (TiO2 films and TiO2/SiNx stacks have potential in surface passivation, anti-reflection coatings and carrier-selective contact layers for crystalline Si solar cells. A Si wafer, deposited with 8-nm-thick TiO2 film by atomic layer deposition, has a surface recombination velocity as low as 14.93 cm/s at the injection level of 1.0 × 1015 cm−3. However, the performance of silicon surface passivation of the deposited TiO2 film declines as its thickness increases, probably because of the stress effects, phase transformation, atomic hydrogen and thermal stability of amorphous TiO2 films. For the characterization of 66-nm-thick TiO2 film, the results of transmission electron microscopy show that the anatase TiO2 crystallinity forms close to the surface of the Si. Secondary ion mass spectrometry shows the atomic hydrogen at the interface of TiO2 and Si which serves for chemical passivation. The crystal size of anatase TiO2 and the homogeneity of TiO2 film can be deduced by the measurements of Raman spectroscopy and spectroscopic ellipsometry, respectively. For the passivating contacts of solar cells, in addition, a stack composed of 8-nm-thick TiO2 film and a plasma-enhanced chemical-vapor-deposited 72-nm-thick SiNx layer has been investigated. From the results of the measurement of the reflectivity and effective carrier lifetime, TiO2/SiNx stacks on Si wafers perform with low reflectivity and some degree of surface passivation for the Si wafer.

  13. Fabrication and photovoltaic properties of heterostructured TiO2 nanowires.

    Science.gov (United States)

    Noh, Suk-In; Park, Dong-Won; Shim, Hee-Sang; Ahn, Hyo-Jin

    2012-07-01

    One-dimensional heterostructured TiO2 nanowires were successfully fabricated by an electrospinning technique and modified by hydrolysis. We investigated their structure, morphology, chemical composition, and optical properties by using the X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy. In the case of the photovoltaic performance, the short-circuit current density and cell efficiency of the DSSCs employing single TiO2 nanowires and heterostructured TiO2 nanowires improve from 6.90 to 11.38 mA/cm2 and from 2.56 to 4.29%, respectively. The results show that the photoconversion efficiency of the heterostructured TiO2 nanowires could be improved by more than approximately 67% compared to that of the single TiO2 nanowires because of the enhanced specific surface area that facilitates dye adsorption.

  14. Fabrication and Characteristics of Macroporous TiO2 Photocatalyst

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    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.

  15. 掺氮TiO2-xNx薄膜托槽生物相容性的实验研究%Biocompatibility of MBT straight wire appliance with nitrogen-doped titania TiO2-xNx film

    Institute of Scientific and Technical Information of China (English)

    张颖杰; 曹宝成; 王育华; 王璞; 张旭; 李娜

    2012-01-01

    目的 制备掺氮TiO2-xNx薄膜托槽并评价薄膜托槽的生物相容性.方法 采用射频磁控溅射法在直丝弓金属托槽原材料试样表面制备锐钛矿相掺氮TiO2-xNx薄膜:①将薄膜材料(薄膜托槽组)和普通托槽材料(普通托槽组)分别缝合于大鼠颊黏膜2侧,2周后肉眼观察和组织学评价薄膜的口腔黏膜刺激性;②分别用薄膜材料(薄膜托槽组)、普通托槽材料(普通托槽组)浸提液和生理盐水(生理盐水组)给小鼠灌胃1周,观察小鼠的临床毒性体征、体质量增长率和重要脏器组织学变化以评价薄膜材料的短期全身毒性作用;③薄膜材料对兔血的溶血实验评价材料的溶血性;④分组同②,各组小鼠在24h内给予对应液灌胃2次,制备小鼠骨髓涂片评价薄膜材料可能的致畸致突变作用.结果 大鼠饮食、活动如常,薄膜托槽组的口腔黏膜与普通托槽组组织学表现一致,表明薄膜托槽无明显口腔黏膜刺激作用;短期全身毒性实验中,3组小鼠体质量增长率差异无统计学意义(P>0.05),所有动物未观察到明显的临床毒性体征,病理解剖也未观察到明显异常,表明薄膜托槽无明显短期全身毒性作用;溶血实验中,薄膜托槽组溶血率<5%,未发现红细胞破象,表明薄膜试样不引起急性溶血;微核实验中生理盐水组、薄膜托槽组和普通托槽组的微核率分别为1.48‰、2.08‰和2.16‰,均低于5‰,且两两之间差异无统计学意义(P>0.05).结论 掺氮TiO2-xNx薄膜托槽无口腔黏膜刺激性、无短期全身毒性、无溶血性以及无遗传毒性,具有良好的生物相容性.%Objective To produce nitrogen-doped titania (Ti02-xNx) film on MBT straight wire appliance and to evaluate its biocompatibility. Methods Radio-frequency magnetron sputtering was applied to produce TiO2-xNx film on the surface of raw material of MBT straight wire appliance. Biocompatibility was evaluated as

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

    OpenAIRE

    Nguyen Huy Hao; Gobinda Gyawali; Tohru Sekino; Soo Wohn Lee

    2016-01-01

    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...

  17. Love Wave Ultraviolet Photodetector Fabricated on a TiO2/ST-Cut Quartz Structure

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

    Institute of Scientific and Technical Information of China (English)

    Nguyen Huy Hao; Gobinda Gyawali; Tohru Sekino; Soo Wohn Lee

    2016-01-01

    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 con-taining 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.

  19. 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.

  20. Fabrication of Pamidronic Acid-Immobilized TiO2/Hydroxyapatite Composite Nanofiber Mats for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Yong-Suk Shin

    2013-01-01

    Full Text Available TiO2/hydroxyapatite (TiO2/HA composite nanofiber mats were fabricated using an electrospinning technique. Subsequently, pamidronic acid (PDA was immobilized on the surface of the TiO2/HA nanofiber mat to improve osseointegration. X-ray photoelectron microscopy and scanning electron microscopy (SEM were used to characterize the structure and morphology of the PDA-immobilized TiO2/HA composite nanofiber mat (TiO2/HA-P. The potential of TiO2/HA-P as a bone scaffold was assessed by examining the cell adhesion and proliferation of osteoblasts and osteoclasts. The adhesion and proliferation of osteoblasts on the TiO2/HA-P composite nanofiber mat were slightly higher than those on the TiO2/HA composite nanofiber mat, whereas the viability of osteoclasts on the TiO2/HA-P nanofiber mat was significantly suppressed. These results suggest that the TiO2/HA-P nanofiber mat has the potential for use as a therapeutic bone implant.

  1. 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.

  2. Fabrication and characterization of photovoltaic devices based on perovskite compounds with TiO2 nanoparticles

    Science.gov (United States)

    Kanayama, Masato; Oku, Takeo; Suzuki, Atsushi; Yamada, Masahiro; Fukunishi, Sakiko; Kohno, Kazufumi; Sakamoto, Hiroki

    2015-02-01

    Perovskite-type photovoltaic devices were fabricated by a spin-coating method using a mixture solution. The compact and meso-porous TiO2 of the solar cells were fabricated from TiO2 nanoparticles and sol, and the photovoltaic properties and microstructures were characterized. The conversion efficiencies were improved by the combination of TiO2 nanoparticles and sol. Current density was also improved by increasing numbers of spin-coatings of meso-porous TiO2. Thick meso-porous TiO2 layers would assist the construction of perovskite layers and block of the leak current.

  3. Fabrication of TiO2 Nanofilm Photoelectrodes on Ti Foil by Ti Ion Implantation and Subsequent Annealing

    Directory of Open Access Journals (Sweden)

    Yichao Liu

    2014-01-01

    Full Text Available The TiO2 photoelectrodes fabricated on the substrate of Ti foils by Ti ions implantation and subsequent annealing at different temperatures were applied for water splitting. The size of TiO2 nanoparticles increased with annealing temperatures, and the GIXRD patterns and Raman spectra demonstrate that the phase of TiO2 turns to rutile at high temperature. The photoelectrochemical (PEC and X-ray photoelectron spectroscopy (XPS spectra of the valence band demonstrate that the samples annealed at 400 and 500°C show the n-type property. The sample annealed at 600°C shows the weak p-type TiO2 property. For the sample annealed at 700°C, the negative photocurrent is main, which mainly performs the p-type property of TiO2. The IPCE values indicate that the absorption edges are red shifted with the increase of annealing temperatures.

  4. 贵金属修饰TiO2-xNx可见光催化活性及催化机理%Visible-Light Photocatalytic Activities and Mechanism of Noble Metal Modified TiO2-xNx Photocatalyst

    Institute of Scientific and Technical Information of China (English)

    鄂磊; 徐明霞; 雅菁; 辛颖; 张春青

    2008-01-01

    采用化学沉淀法通过自掺杂制备了纳米TiO2-xNx粉体,并采用无机粘结剂法将其负载在基片上,再通过滴涂法对其进行贵金属修饰,从而得到修饰型光催化剂M/TiO2-xNx.采用XRD,XPS,UV-Vjs等测试对其进行表征,并以甲基橙溶液为光催化降解对象,研究了M/TiO2-xNx的可见光活性.研究发现在负载TiO2-xNx表面沉积Ag,Pt,Pd和Rh均可提高其光催化活性.在最佳掺杂量时,M/TiO2-xNx的可见光活性的顺序为Pd/TiO2-xNx>Pt/TiO2-xNx>Rh/TiO2-xNx>Ag/TiO2-xNx>TiO2-xNx.光催化机理分析表明M/TiO2-xNx光催化剂的活性取决于光生电子的激发方式及其转移途径.

  5. Fabrication and characterization of perovskite photovoltaic devices with TiO2 nanoparticle layers

    Science.gov (United States)

    Oku, Takeo; Ueoka, Naoki; Suzuki, Kohei; Suzuki, Atsushi; Yamada, Masahiro; Sakamoto, Hiroki; Minami, Satoshi; Fukunishi, Sakiko; Kohno, Kazufumi; Miyauchi, Shinsuke

    2017-01-01

    TiO2/CH3NH3PbI3-based photovoltaic devices were fabricated by a spin-coating method using mixture solutions with TiO2 nanoparticles. Compact TiO2 layers were prepared from titanium diisopropoxide bis(acetyl acetonate) and TiO2 nanoparticles with different particle sizes. The performance of the photovoltaic devices was improved by sequential deposition of the TiO2 layers, which resulted in microstructural change of the perovskite layers.

  6. USE OF BATTERY CARBON AS ELECTRODES IN ARC DISCHARGE METHOD FOR FABRICATION OF CARBON-MODIFIED TIO2

    Directory of Open Access Journals (Sweden)

    Isya Fitria Andhika

    2016-09-01

    Full Text Available Fabrication with carbon-modified TiO2 by arc discharge method in liquid medium has been studied. This research was performed in two steps including fabrication and characterization. This fabrication was done by arcdischarge method with graphite electrodes from dry cell batteries and liquid medium suspension of TiO2 in ethanol 30, 50 and 70 %. A strong current was applied to electrode as 10 -50 A (20-40 V. Nanocomposites formed on the liquid medium surface were collected and characterized using X-ray diffraction (XRD,scanning electron microscope (SEM dan energy dispersive spectroscopy (EDS to determine crystallinity, surface morphology and the constituent elements, respectively. XRD data shows that the most effective fabrication TiO2/Karbon by liquid medium in ethanol 50 % indicated from the formation of a new peak with high intensity of TiC on 2Ɵ= 36.02 °. SEM data shows that the morphology of each aggregated TiO2/Karbon compared to the morphology of TiO2. In addition, EDS data shows the presence of the element carbon, titanium and oxygen in the same area indicating that the successful formation of composite material between TiO2 dan carbon.

  7. Fabrication and Photocatalytic Characteristics of TiO2 Films on Silicon Substrates

    Institute of Scientific and Technical Information of China (English)

    YANG Jia-long; WANG Fu; ZUO Liang; YI Gu-chul; CHOI Wong-yong

    2005-01-01

    Silicon (111) and Silicon (100) have been employed for fabrication of TiO2 films by metal organic chemical vapor deposition (MOCVD). Titanium (Ⅳ) isopropoxide (Ti[O(C3H7)4]) was used as a precursor. The as-deposited TiO2 films have been characterized with Field emission scanning electron microscopy(FE-SEM), X ray diffraction (XRD) and atomic force microscopy (AFM). The photocatalytic properties were investigated by decomposition of aqueous orange Ⅱ. The crystalline and structural properties of TiO2 film had crucial influences on the photodegradation efficiency. For MOCVD in-situ deposited films on Si substrates, the photoactivities varied following a shape of "M": At lower (350 ℃) middle (500 ℃) and higher (800 ℃) temperature of deposition, relative lower photodegradation activities have been observed. At 400 ℃ and 700 ℃ of deposition, relative higher efficiencies of degradation have been obtained, because one predominant crystallite orientation could be obtained as deposition at those two temperatures, especially a single anatase crystalline TiO2 film could be obtained at 700 ℃ growth.

  8. Reprint of: photostability of wool fabrics coated with pure and modified TiO2 colloids.

    Science.gov (United States)

    Pakdel, Esfandiar; Daoud, Walid A; Sun, Lu; Wang, Xungai

    2015-06-01

    The surface of wool fabrics was coated with TiO2 and TiO2-based nanocomposite colloids and the impact of this coating on the photostability of wool was investigated. TiO2 along with TiO2/Metal and TiO2/Metal/SiO2 sols were synthesized through a low-temperature sol-gel method and applied to fabrics. Composite colloids were synthesized through integrating the silica and three noble metals of silver (Ag), gold (Au) and platinum (Pt) into the synthesis process of sols. Four different molar ratios of Metal to TiO2 (0.01%, 0.1%, 0.5% and 1%) were used to elucidate the role of metal type and amount on the obtained features. Photostability and UV protection features of fabrics were evaluated through measuring the photo-induced chemiluminescence (PICL), photoyellowing rate and ultraviolet protection factor (UPF) of fabrics. PICL and photoyellowing tests were carried out under UVA and UVC light sources, respectively. PICL profiles demonstrated that the presence of pure and modified TiO2 nanoparticles on fabrics reduced the intensity of PICL peak indicating a lower amount of polymer free radicals in coated wool, compared to that of pristine fabric. Moreover, a higher PICL peak intensity as well as photoyellowing rate was observed on fabrics coated with modified colloids in comparison with pure TiO2. The surface morphology of fabrics was further characterized using FESEM images.

  9. Photostability of wool fabrics coated with pure and modified TiO2 colloids.

    Science.gov (United States)

    Pakdel, Esfandiar; Daoud, Walid A; Sun, Lu; Wang, Xungai

    2015-02-15

    The surface of wool fabrics was coated with TiO2 and TiO2-based nanocomposite colloids and the impact of this coating on the photostability of wool was investigated. TiO2 along with TiO2/Metal and TiO2/Metal/SiO2 sols were synthesized through a low-temperature sol-gel method and applied to fabrics. Composite colloids were synthesized through integrating the silica and three noble metals of silver (Ag), gold (Au) and platinum (Pt) into the synthesis process of sols. Four different molar ratios of Metal to TiO2 (0.01%, 0.1%, 0.5% and 1%) were used to elucidate the role of metal type and amount on the obtained features. Photostability and UV protection features of fabrics were evaluated through measuring the photo-induced chemiluminescence (PICL), photoyellowing rate and ultraviolet protection factor (UPF) of fabrics. PICL and photoyellowing tests were carried out under UVA and UVC light sources, respectively. PICL profiles demonstrated that the presence of pure and modified TiO2 nanoparticles on fabrics reduced the intensity of PICL peak indicating a lower amount of polymer free radicals in coated wool, compared to that of pristine fabric. Moreover, a higher PICL peak intensity as well as photoyellowing rate was observed on fabrics coated with modified colloids in comparison with pure TiO2. The surface morphology of fabrics was further characterized using FESEM images.

  10. RF磁控溅射技术制备TiO2-xNx薄膜及组成和结构研究%Compositional and structural properties of TiO2-xNx thin films deposited by RF magnetron sputtering

    Institute of Scientific and Technical Information of China (English)

    景士伟; 刘益春; 梁宇; 马健钢; 吕有明; 申德振; 张吉英; 范希武

    2005-01-01

    利用RF磁控溅射技术(Ar,N2和O2混合气体,Ti金属靶)制备TiO 2-xNx薄膜.用XRD和XPS对其结构和组成进行表征,结果表明:在实验系统中的N2含量在13%~17%之间,可以得到高质量的TiO 2-xNx薄膜,β-N为 TiO 2-xNx薄膜的主要成分;不同含N量的TiO 2-xNx薄膜的结构和组成的光学催化活性不同.

  11. Enhanced performance of natural dye sensitised solar cells fabricated using rutile TIO2 nanorods

    Science.gov (United States)

    Akila, Y.; Muthukumarasamy, N.; Agilan, S.; Mallick, Tapas K.; Senthilarasu, S.; Velauthapillai, Dhayalan

    2016-08-01

    Due to the lower cost, natural dye molecules are good alternatives for the ruthenium based sensitizers in the dye-sensitized solar cells. In this article, we have reported the natural sensitizer based dye-sensitized solar cells fabricated using TiO2 nanorods. Rutile phase TiO2 nanorods have been synthesized by template free hydrothermal method which results in TiO2 nanorods in the form of acropora corals. These TiO2 nanorods have been sensitized by flowers of Sesbania grandiflora, leaves of Camellia sinensis and roots of Rubia tinctorum. The maximum conversion efficiency of 1.53% has been obtained for TiO2 nanorods based solar cells sensitized with the leaves of Camellia sinensis. The flowers of Sesbania grandiflora and roots of Rubia tinctorum sensitized TiO2 nanorods based solar cells exhibited an efficiency of 0.65% and 1.28% respectively.

  12. Antibacterial and UV protective properties of polyamide fabric impregnated with TiO2/Ag nanoparticles

    OpenAIRE

    Milošević Milica; Krkobabić Ana; Radoičić Marija; Šaponjić Zoran; Lazić Vesna; Stoiljković Milovan; Radetić Maja

    2015-01-01

    The possibility of in situ photoreduction of Ag+ ions using colloidal TiO2 nanoparticles deposited on the surface of polyamide fabric in the presence of amino acid alanine and methyl alcohol is discussed. The presence of TiO2/Ag nanoparticles on the polyamide fabric was confirmed by FESEM and ICP analyses. Antibacterial activity of the fabric was tested against Gram-negative bacterium Escherichia coli and Gram-positive bacterium Staphylococcus aureus. Fabri...

  13. Effect of SiNx diffusion barrier thickness on the structural properties and photocatalytic activity of TiO2 films obtained by sol–gel dip coating and reactive magnetron sputtering

    Directory of Open Access Journals (Sweden)

    Mohamed Nawfal Ghazzal

    2015-10-01

    Full Text Available We investigate the effect of the thickness of the silicon nitride (SiNx diffusion barrier on the structural and photocatalytic efficiency of TiO2 films obtained with different processes. We show that the structural and photocatalytic efficiency of TiO2 films produced using soft chemistry (sol–gel and physical methods (reactive sputtering are affected differentially by the intercalating SiNx diffusion barrier. Increasing the thickness of the SiNx diffusion barrier induced a gradual decrease of the crystallite size of TiO2 films obtained by the sol–gel process. However, TiO2 obtained using the reactive sputtering method showed no dependence on the thickness of the SiNx barrier diffusion. The SiNx barrier diffusion showed a beneficial effect on the photocatalytic efficiency of TiO2 films regardless of the synthesis method used. The proposed mechanism leading to the improvement in the photocatalytic efficiency of the TiO2 films obtained by each process was discussed.

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

    Science.gov (United States)

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

    2016-04-01

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

  15. Highly photocatalytic TiO2 interconnected porous powder fabricated by sponge-templated atomic layer deposition

    Science.gov (United States)

    Pan, Shengqiang; Zhao, Yuting; Huang, Gaoshan; Wang, Jiao; Baunack, Stefan; Gemming, Thomas; Li, Menglin; Zheng, Lirong; Schmidt, Oliver G.; Mei, Yongfeng

    2015-09-01

    A titanium dioxide (TiO2) interconnected porous structure has been fabricated by means of atomic layer deposition of TiO2 onto a reticular sponge template. The obtained freestanding TiO2 with large surface area can be easily taken out of the water to solve a complex separation procedure. A compact and conformal nanocoating was evidenced by morphologic characterization. A phase transition, as well as production of oxygen vacancies with increasing annealing temperature, was detected by x-ray diffraction and x-ray photoelectron spectroscopy, respectively. The photocatalytic experimental results demonstrated that the powder with appropriate annealing treatment possessed excellent photocatalytic ability due to the co-action of high surface area, oxygen vacancies and the optimal crystal structure.

  16. Laser deposition of TiO2 nanoparticles on glass fabric

    Science.gov (United States)

    Wiener, J.; Shahidi, S.; Goba, M. M.

    2013-02-01

    In this research work light laser irradiation was used for deposition of titanium dioxide nanoparticles on the surface of glass mat. For this purpose TiO2 nanoparticles were evenly applied on the surface of a glass fiber mat. The glass fiber mat containing the metals was then irradiated with the laser light beam (100 μs). The morphology of the fabrics was observed using a Scanning Electron Microscope. An X-ray fluorescence spectrum and energy dispersive X-ray were used for elemental analysis. Also mechanical properties and air permeability of the irradiated samples were analyzed and the results show that both tenacity and elongation of laser irradiated sample are reduced but the air permeability is improved after laser irradiation. The photocatalytic activities of TiO2 deposited glass fabrics were assessed by analyzing the decrease in concentration of the Orange II as a colorant after exposure to UV irradiation. The results clarify that the Orange II concentration decreases continuously, concomitant with the UV irradiation time up to 270 min.

  17. Fabrication of visible-light responsive S-F-codoped TiO2 nanotubes

    Institute of Scientific and Technical Information of China (English)

    CHEN XiuQin; SU YaLing; ZHANG XingWang; LEI LeCheng

    2008-01-01

    Fabrication and S-F-codoping of TiO2 nanotubes were carried out by a one-step electrochemical ano-dization process to extend the photoresponse of TiO2 to the visible-light region. The prepared samples were annealed in air and deteoted by SEM, XRD, XPS and UV-vis DRS speotrophotometer. The results showed that the average tube diameter of the nanotubes was 150 nm and the average tube length was 400 nm. The doped TiO2 nanotubes exhibited strong absorption in visible-light region. Photoelectro- catalytic degradation efficiency of 4-CP over S-F-codoped TiO2 nanotubes was 39.7% higher than that of only-F-doped sample. Moreover, sulfur and fluorine codoped into substitutional sites of TiO2 had been proven to be indispensable for strong response and high photocatalytic activity under visible light, as assessed by XPS.

  18. A facile method for fabricating TiO2@mesoporous carbon and three-layered nanocomposites.

    Science.gov (United States)

    Liu, Yong; Jin, Haibao; Zhu, Shenmin; Liu, Yunchun; Long, Mingce; Zhou, Yongfeng; Yan, Deyue

    2012-08-17

    Herein, we report a new and facile method for fabricating TiO(2)@mesoporous carbon hybrid materials. Uniform polydopamine (PDA) layers were coated onto the surface of titanate nanotubes (TNTs) and TiO(2) nanorods (TNDs) through the spontaneous adhesion and self-polymerization of dopamine during the dipping process. Core-shell mesoporous carbon nanotubes with TiO(2) nanorods or nanoparticles encapsulated inside (TiO(2)@MC) were then obtained by transforming PDA layers into carbonaceous ones through calcination in nitrogen at 800 °C. The thickness of the mesoporous carbon layers is tens of nanometers and can be controlled by adjusting the coated PDA layers through the self-polymerization reaction time. In addition, three-layered nanocomposites of TiO(2)@MC@MO (MO, metal oxide) can be readily prepared by utilizing PDA layers in TNTs@PDA or TNDs@PDA to adsorb the metal ions, followed by the calcination process.

  19. Fabrication of TiO2/Carbon Photocatalyst using Submerged DC Arc Discharged in Ethanol/Acetic Acid Medium

    Science.gov (United States)

    Saraswati, T. E.; Nandika, A. O.; Andhika, I. F.; Patiha; Purnawan, C.; Wahyuningsih, S.; Rahardjo, S. B.

    2017-05-01

    This study aimed to fabricate a modified photocatalyst of TiO2/C to enhance its performance. The fabrication was achieved using the submerged direct current (DC) arc-discharge method employing two graphite electrodes, one of which was filled with a mixture of carbon powder, TiO2, and binder, in ethanol with acetic acid added in various concentrations. The arc-discharge method was conducted by flowing a current of 10-20 A (~20 V). X-ray diffraction (XRD) patterns showed significant placements of the main peak characteristics of TiO2, C graphite, and titanium carbide. The surface analysis using Fourier transform infrared spectroscopy (FTIR) revealed that fabricated TiO2/C nanoparticles had stretching vibrations of Ti-O, C-H, C═O, C-O, O-H and C═C in the regions of 450-550 cm-1, 2900-2880 cm-1, 1690-1760 cm-1, 1050-1300 cm-1, 3400-3700 cm-1 and ~1600 cm-1, respectively. In addition, the study investigated the photocatalysts of unmodified and modified TiO2/C for photodegradation of methylene blue (MB) dye solution under mercury lamp irradiation. The effectiveness of the degradation was defined by the decrease in 60-minute absorbance under a UV-Vis spectrophotometer. Modified TiO2/C proved to be significantly more efficient in reducing dye concentrations, reaching ~70%. It indicated that the oxygen-containing functional groups have been successfully attached to the surface of the nanoparticles and played a role in enhancing photocatalytic activity.

  20. Synthesis, characterization, and photocatalytic activity of TiO(2-x)N(x) nanocatalyst.

    Science.gov (United States)

    Wang, Y Q; Yu, X J; Sun, D Z

    2007-06-01

    Nitrogen-doped titanium dioxide powders were prepared by wet method, that is, the hydrolysis of acidic tetra-butyl titanate using aqueous ammonia solution, followed by calcination at temperatures about 350 degrees C. The catalysts exhibited photocatalytic activity in the visible light region owing to N-doping. The light absorption onset of TiO(2-x)N(x) was shifted to the visible region at 459 nm compared to 330 nm of pure TiO(2). An obvious decrease in the band gap was observed by the optical absorption spectroscopy, which resulted from N2p localized states above the valence band of TiO(2-x)N(x) (compared to TiO(2)). The TiO(2-x)N(x) catalyst was characterized to be anatase with oxygen-deficient stoichiometry by X-ray diffraction (XRD), surface photovoltage spectroscopy (SPS) and X-ray photoelectron spectroscopy (XPS). The binding energy of N1s measured by XPS characterization was 396.6 eV (TiN bonds, beta-N) and 400.9 eV (NN bonds, gamma-N(2)), respectively. The photocatalytic activity of TiO(2-x)N(x) under visible light was induced by the formation of beta-N in the structure. Photocatalytic decomposition of benzoic acid solutions was carried out in the ultraviolet and visible (UV-vis) light region, and the TiO(2-x)N(x) catalyst showed higher activity than pure TiO(2).

  1. Fabrication and Photocatalytic Activity of Ag3PO4-TiO2 Heterostructural Nanotube Arrays

    Institute of Scientific and Technical Information of China (English)

    MO Yanping; CHEN Feng; YANG Yunyun; SONG Jia; XU Qiong; XU Ying

    2016-01-01

    To extend the absorption capability of TiO2 into visible light region and inhibit the recombination of photogenerated electrons and holes, we put forward an effective strategy of the coupling of TiO2 with a suitable semiconductor that possesses a narrow band gap. Meanwhile, Ag3PO4-TiO2 heterostructural nanotube arrays were prepared by the two-step anodic oxidation to obtain the TiO2 nanotube arrays and then by a deposition-precipitation method to load Ag3PO4. The samples were characterized by ifeld emission scanning electron microscopy (FESEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), and UV-vis diffuse relfectance spectroscopy (UV-vis DRS). The experimental results showed that Ag3PO4nanoparticles were uniformly dispersed on the highly ordered TiO2 nanotube arrays, which increased the visible-light absorption of TiO2 photocatalyst. The photocurrent density and photocatalytic degradation of methyl orange indicated that the performance of Ag3PO4-TiO2 heterostructural nanotube arrays was better than that of the TiO2 nanotube arrays, which could be attributed to the effective electron-hole separation and the improved utilization of visible light.

  2. Photocatalytic Nanocomposite Films Fabricated by Layer-by-Layer Self-assembly of TiO2 Nanoparticles and Lignosulfonates

    Institute of Scientific and Technical Information of China (English)

    李辉; 付时雨; 彭林才; 詹怀宇

    2012-01-01

    Photocatalytic multilayer nanocomposite films composed of anatase TiO2 nanoparticles and lignosulfonates (LS) were fabricated on quartz slides by the layer-by-layer (LBL) self-assembly technique. X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy and atomic force microscopy (AFM) were used to characterize the TiO2/LS multilayer nanocomposite films. Moreover, the photocatalytic properties (decomposition of methyl orange and bacteria) of multilayer nanocomposite films were investigated. XPS results indicated that the intensities of titanium and sulfur peaks increased with the LBL deposition process. A linear increase in absorbance at 280 nm was found by UV-Vis spectroscopy, suggesting that stepwise multilayer growth occurs on the substrate and this deposition process is highly reproducible. AFM images showed that quartz slide was completely covered by TiO2 nanoparticles when a 10-bilayer multilayer film was formed. The decomposition efficiency of methyl orange by TiOz/LS multilayer films under the same UV irradiation time increased linearly with the number of TiO2 layers, and the results of decomposition of bacteria under UV irradiation showed that TiO2/LS multilayer nanocomposite films exhibited excellent decomposition activity of bacteria (Escherichia coil).

  3. Sonosynthesis of nano TiO2 on wool using titanium isopropoxide or butoxide in acidic media producing multifunctional fabric.

    Science.gov (United States)

    Behzadnia, Amir; Montazer, Majid; Rashidi, Abousaeid; Rad, Mahnaz Mahmoudi

    2014-09-01

    This study presents a novel idea to prepare nanocrystalline structure of TiO2 under ambient pressure at 60-65 °C using in situ sonochemical synthesis by hydrolysis of either titanium isopropoxide or titanium butoxide in an acidic aqueous solution. The nano titanium dioxide coated wool fabrics possess significant antibacterial/antifungal activity and self-cleaning property by discoloring Methylene blue stain under sunlight irradiation. This process has no negative effect on cytotoxicity and tensile strength of the sonotreated fabric even reduces alkaline solubility and photoyellowing and improves hydrophilicity. More titanium isopropoxide or titanium butoxide as a precursor led to higher photocatalytic activities of the treated fabrics. Also introducing more ethanol improved the adsorption of TiO2 on the wool fabric surface leading to enhanced photocatalytic activity. EDS and XRD patterns, SEM images, X-ray mapping confirmed the presence of nano TiO2 particles on the fabric surface. The role of both solvent and precursor concentrations on the various properties of the fabric was investigated and the optimized conditions were obtained using response surface methodology.

  4. Antibacterial and UV protective properties of polyamide fabric impregnated with TiO2/Ag nanoparticles

    Directory of Open Access Journals (Sweden)

    Milošević Milica

    2015-01-01

    Full Text Available The possibility of in situ photoreduction of Ag+ ions using colloidal TiO2 nanoparticles deposited on the surface of polyamide fabric in the presence of amino acid alanine and methyl alcohol is discussed. The presence of TiO2/Ag nanoparticles on the polyamide fabric was confirmed by FESEM and ICP analyses. Antibacterial activity of the fabric was tested against Gram-negative bacterium Escherichia coli and Gram-positive bacterium Staphylococcus aureus. Fabricated TiO2/Ag nanoparticles on the surface of polyamide fabric provided maximum bacterial reduction and thus, excellent antibacterial activity. In spite of silver leaching from the fabric during washing, impregnated polyamide fabric preserved maximum reduction of Escherichia coli colonies. Antibacterial activity against Staphylococcus aureus slightly decreased after ten washing cycles, but still antibacterial activity can be considered as satisfactory. In addition, the presence of TiO2/Ag nanoparticles ensured better UV protection efficiency which belongs to very good UV protection category. [Projekat Ministarstva nauke Republike Srbije, br. 45020 i br. 172056

  5. Mesoporous TiO2 films fabricated using atmospheric pressure dielectric barrier discharge jet.

    Science.gov (United States)

    Seo, Hyung-Kee; Elliott, C Michael; Shin, Hyung-Shik

    2010-12-01

    TiO2 nanoparticles were synthesized by a facile method of dielectric barrier discharge jet (DBD jet) for the dye-sensitized solar cell (DSSC) and other potential applications. DBD jet is utilized as a method for deposition of TiO2 nanoparticles with a 9 μm/min growth rate which is more than ×25 faster than reported previously. Their performance was compared with cells fabricated using commercial TiO2 nanoparticles (P25). The crystallinity and chemical bonding states of samples were characterized by XRD and XPS. Photoanodes fabricated by the DBD jet method resulted in approximately 50% higher photoconversion efficiency than ones prepared from P25 nanoparticles.

  6. Fabrication of UV Photodetector on TiO2/Diamond Film.

    Science.gov (United States)

    Liu, Zhangcheng; Li, Fengnan; Li, Shuoye; Hu, Chao; Wang, Wei; Wang, Fei; Lin, Fang; Wang, Hongxing

    2015-09-24

    The properties of ultraviolet (UV) photodetector fabricated on TiO2/diamond film were investigated. Single crystal diamond layer was grown on high-pressure-high-temperature Ib-type diamond substrate by microwave plasma chemical vapor deposition method, upon which TiO2 film was prepared directly using radio frequency magnetron sputtering technique in Ar and O2 mixing atmosphere. Tungsten was used as electrode material to fabricate metal-semiconductor-metal UV photodetector. The dark current is measured to be 1.12 pA at 30 V. The photo response of the device displays an obvious selectivity between UV and visible light, and the UV-to-visible rejection ratio can reach 2 orders of magnitude. Compared with that directly on diamond film, photodetector on TiO2/diamond film shows higher responsivity.

  7. Photocatalytic degradation of dimethoate using LbL fabricated TiO2/polymer hybrid films.

    Science.gov (United States)

    Priya, D Neela; Modak, Jayant M; Trebše, Polonca; Zabar, Romina; Raichur, Ashok M

    2011-11-15

    Degradation of dimethoate under UV irradiation using TiO(2)/polymer films prepared by the layer-by-layer (LbL) method was investigated. The thin films were fabricated on glass slides and the surface morphology and roughness of the thin films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The effect of lamp intensity, catalyst loading in the layers, number of bilayers, pH and initial dimethoate concentration on the degradation of dimethoate was systematically studied. The degradation was monitored using high performance liquid chromatography (HPLC) analysis and total organic carbon (TOC) measurements as a function of irradiation time, to see the change in concentration of dimethoate and mineralization, respectively. Complete degradation of dimethoate was achieved under TiO(2) optimum loading of 4 g/L at an UV irradiation time of 180 min. Increase in the lamp intensity, catalyst loading and number of bilayers increased the rate of degradation. At a pH of 4.62, complete degradation of dimethoate was observed. The degradation efficiency decreased with increase in initial dimethoate concentration. The degradation byproducts were analyzed and confirmed by gas chromatography-mass spectra (GC-MS). Toxicity of the irradiated samples was measured using the luminescence of bacteria Vibrio fischeri after 30 min of incubation and the results showed more toxicity than the parent compound. Catalyst reusability studies revealed that the fabricated thin films could be repeatedly used for up to ten times without affecting the photocatalytic activity of the films. The findings of the present study are very useful for the treatment of wastewaters contaminated with pesticides.

  8. TiO2 Nanowire dye-sensitized solar cells Fabricated by Hydrothermal Method

    Science.gov (United States)

    Xu, Yang; Gu, Haoshuang; Xia, Huating; Hu, Mingzhe

    2011-02-01

    TiO2 nanowire dye-sensitized solar cells were fabricated by using hydrothermal method. The synthesizing of TiO2 nanowire/nanorod arrays directly on FTO substrate would cause a high conducting loss to solar cells. Through la minating a compact layer between FTO substrate and photonic anode layer, the conducting loss could be effectively prevented. Results indicated that using different concentration of titanium tetrabutoxide would affect the photoelectric conversion efficiency and different producing methods of the compact layer also played an important role to the conversion efficiency.

  9. A facile method for fabricating TiO2@mesoporous carbon and three-layered nanocomposites

    Science.gov (United States)

    Liu, Yong; Jin, Haibao; Zhu, Shenmin; Liu, Yunchun; Long, Mingce; Zhou, Yongfeng; Yan, Deyue

    2012-08-01

    Herein, we report a new and facile method for fabricating TiO2@mesoporous carbon hybrid materials. Uniform polydopamine (PDA) layers were coated onto the surface of titanate nanotubes (TNTs) and TiO2 nanorods (TNDs) through the spontaneous adhesion and self-polymerization of dopamine during the dipping process. Core-shell mesoporous carbon nanotubes with TiO2 nanorods or nanoparticles encapsulated inside (TiO2@MC) were then obtained by transforming PDA layers into carbonaceous ones through calcination in nitrogen at 800 °C. The thickness of the mesoporous carbon layers is tens of nanometers and can be controlled by adjusting the coated PDA layers through the self-polymerization reaction time. In addition, three-layered nanocomposites of TiO2@MC@MO (MO, metal oxide) can be readily prepared by utilizing PDA layers in TNTs@PDA or TNDs@PDA to adsorb the metal ions, followed by the calcination process.

  10. The design, fabrication, and photocatalytic utility of nanostructured semiconductors: focus on TiO2-based nanostructures

    Directory of Open Access Journals (Sweden)

    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

  11. FUNCTIONALISATION OF TEXTILE FABRICS WITH STABILIZED TiO2 DISPERSIONS

    Directory of Open Access Journals (Sweden)

    POPESCU Alina

    2016-05-01

    Full Text Available This study approached the experimentation of deposition by padding of some TiO2 P25 dispersed photocatalytic systems on RIPSTOP fabric, made of 100% cotton yarns Nm 70/1 and a network of polyester filament yarns 330 dtex, both in warp and weft directions. As stabilizers for photocatalytic dispersions the following products have been used: dodecyltrimethylamonnium bromide (DTAB, 2-[2-(2-methoxyethoxyethoxy] acetic acid (TODA and poly(ethyleneglycol (PEG. Prior to functionalisation treatment, preliminary preparation in three successive steps were applied on textile materials (enzymatic desizing, hot alkaline treatment and bleaching, being followed by cationisation with a polyethylene polyamine resin or a pre-treatment with different crosslinking agents based on acrylic copolymer, polycarbonate urethane polymer or urethane resin. The photocatalytic activity of the textile materials treated with synthesized dispersions was investigated using methylene blue as pollutant. The evaluation was made before and after one washing cycle, in order to determine the durability to washing of applied treatments. Electron microscopy was used for viewing the distribution of TiO2 particles on the surface of textile materials treated with the photocatalytic dispersions. Ti content existing on the surface of the textile materials was performed by energy dispersive X-ray spectroscopy. The sample treated with photocatalytic dispersion stabilized with TODA showed the higher photocatalytic activity, for which the greatest degree of discoloration was achieved after six hours UV irradiation. Pre-treatment with crosslinking type urethane resin offers good durability to washing of photocatalytic dispersions stabilized with TODA and PEG, confirmed by obtaining a discoloration after washing comparable to that obtained for the unwashed sample.

  12. The design, fabrication, and photocatalytic utility of nanostructured semiconductors: focus on TiO2-based nanostructures.

    Science.gov (United States)

    Banerjee, Arghya Narayan

    2011-02-15

    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

  13. Hall Mobilities in GaNxAs1-x

    Science.gov (United States)

    2010-01-01

    Walukiewicz2, and Germán Gonzalez-Díaz1 1 Dpto. de Física Aplicada III, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, Madrid 28040...Ref. [15] temperature behavior of GaNxAs1-x mobility is modeled, but this model does not account for the different temperature dependences presented

  14. FABRICATION AND PHOTOCATALYTIC PROPERTIES OF TiO2 NANOFILMS CO-DOPED WITH Fe3+ AND Bi3+ IONS

    Science.gov (United States)

    Gao, Qiongzhi; Liu, Xin; Liu, Wei; Liu, Fang; Fang, Yueping; Zhang, Shiying; Zhou, Wuyi

    2016-12-01

    In this work, the titanium dioxide (TiO2) nanofilms co-doped with Fe3+ and Bi3+ ions were successfully fabricated by the sol-gel method with dip-coating process. Methylene blue was used as the target degradation chemical to study the photocatalytic properties affected by different doping contents of Fe3+ and Bi3+ ions. The samples were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and infrared (IR) spectroscopy. The results indicated that both pure TiO2 nanofilms and single-doped samples possessed the photocatalytic activity in degradation of methylene blue. However, when the nanofilms co-doped with Fe3+ and Bi3+ ions were fabricated at the molar ratio of 3:1 (Fe3+:Bi3+), they exhibited the best photocatalytic activity after the heat treatment at 500∘C for 2h. The wettability property test indicated that the TiO2 nanofilms co-doped with Fe3+ and Bi3+ ions in the molar ratio 3:1 owned an excellent hydrophilic property.

  15. Fabrication of Nanostructured TiO2 Using a Solvothermal Reaction for Lithium-ion Batteries

    Directory of Open Access Journals (Sweden)

    Jicai Liang

    2016-03-01

    Full Text Available Nanostructured TiO2 was successfully synthesized via a facile one-pot solvothermal reaction followed by calcina‐ tion. Hydrolysis and polycondensation of titanium butox‐ ide (Ti(OR4 were performed in the presence of sodium dodecylbenzenesulfonate (SDBS. The morphologies, crystallinity and compositions of obtained samples were identified by the methods of X-ray diffraction (XRD, Brunauer–Emmett–Teller (BET and transmission electron microscopy (TEM. It was found that the nanostructured TiO2 with an average diameter of 10±5 nm had the crystal type of anatase. A good specific surface was also obtained by the standard multipoint BET method (119.2 m2/g. As the anode materials for the lithium-ion batteries (LIBs, the anatase phase TiO2 demonstrated a relatively high gravi‐ metric specific capacity of 264.8 mAh g-1. The reversible capacity of TiO2 remained 196.4 mAh g-1 at a rate of 0.2 ̊C after 100 cycles. It indicated that this kind of TiO2 possessed a good electrochemical performance.

  16. Facile fabrication of TiO2-graphene composite with enhanced photovoltaic and photocatalytic properties by electrospinning.

    Science.gov (United States)

    Zhu, Peining; Peining, Zhu; Nair, A Sreekumaran; Shengjie, Peng; Shengyuan, Yang; Ramakrishna, Seeram

    2012-02-01

    We report the fabrication of one-dimensional TiO(2)-graphene nanocomposite by a facile and one-step method of electrospinning. The unique nanostructured composite showed a significant enhancement in the photovoltaic and photocatalytic properties in comparison to TiO(2) as demonstrated in dye-sensitized solar cells and photodegradation of methyl orange.

  17. Bactericidal activity under UV and visible light of cotton fabrics coated with anthraquinone-sensitized TiO2

    KAUST Repository

    Rahal, Raed

    2013-06-01

    This study describes a method derived from ISO/TC 206/SC specifications to assess the bactericidal activity against a bacterial strain, Pseudomonas fluorescens, of various photocatalytic fabrics, under UVA and filtered visible light. The experimental method allowed the accurate quantification of bacteria survival on photoactive surfaces and films under UVA and UV-free visible irradiation. Cotton fabrics coated with TiO2, anthraquinone or anthraquinone-sensitized TiO2 display a significant bactericidal efficiency. TiO2-coated fabrics are very efficient against P. fluorescens after 4 h UVA irradiation (bacteria survival below the detection limit). Under UVA-free visible light, anthraquinone-sensitized TiO2 coated fabrics induced a significant bactericidal activity after 2 h irradiation, while anthraquinone alone-coated fabrics were not as efficient and TiO2 coated fabrics were almost inefficient. These results show that although exhibiting a weak n-π* band in the 350-420 nm range, anthraquinone is a good candidate as an efficient visible light photosensitizer. A synergy effect between anthraquinone and TiO2 was demonstrated. A possible reaction mechanism, involving a synergy effect for singlet oxygen formation with anthraquinone-sensitized TiO2 is proposed to account for these results. © 2012 Elsevier B.V. All rights reserved.

  18. Highly flexible TiO2-coated stainless steel fabric electrode prepared by liquid-phase deposition

    Science.gov (United States)

    Hwang, Hong Seo; Lee, Jeong Beom; Jung, Jiwon; Lee, Seyoung; Ryu, Ji Heon; Oh, Seung M.

    2016-10-01

    In order to construct flexible lithium-ion batteries, stainless steel (SUS) fabric is used as a current collector for the negative electrode of lithium-ion batteries. TiO2 is coated onto the SUS fabric by liquid-phase deposition to construct an electrode consisting of an SUS wire core and a TiO2 shell. A folding test is then conducted to assess the robustness of TiO2-coated SUS fabric, during which no detachment of TiO2 particles from the SUS current collector is observed; the negative electrode shows a consistent electrochemical cycle performance even under severe physical duress. The TiO2-SUS fabric integration shows excellent flexibility without loss of electrochemical efficacy under mechanical stress, which occurs owing to three main factors. First, the mechanical stress imposed by folding is effectively dissipated by the 3-dimensional structure of the SUS fabric. Secondly, the TiO2 electrode itself is free from mechanical stress owing to negligible volume change during electrochemical cycling. Thirdly, the high interfacial adhesion strength between TiO2 and SUS fabric due to covalent bond formation during liquid-phase deposition prevents the loss of active material from the negative electrode during the folding tests.

  19. Photocatalytic performance of melt-electrospun polypropylene fabric decorated with TiO2 nanoparticles

    Science.gov (United States)

    Karahaliloglu, Zeynep; Hacker, Christoph; Demirbilek, Murat; Seide, Gunnar; Denkbas, Emir Baki; Gries, Thomas

    2014-09-01

    Recently, nanomaterials, especially titanium-based nanomaterials, have a great potential for decolorization of textile dye effluents. In this article, the nanofibrillar filters functionalized with titanium nanoparticle (nTi) were designed to improve dyeing wastewater decolorization. Pristine polypropylene (PP) and nTi-PP nanocomposite nonwovens were produced as a photocatalyzer by melt-electrospinning process. The average diameter of pristine PP- and nTi-PP nanocomposite melt-electrospun fibers was found average as 700 ± 0.3 and 800 ± 0.4 nm, respectively. Before functionalization with nTi, the surface of fabrics was activated by a technique using glutaraldehyde (GA) and polyethyleneimine to improve decomposition activity. Scanning electron microscopy (SEM) results revealed that titanium nanoparticles were deposited uniformly on the nanofibers. X-ray photon spectroscopy (XPS) results confirmed the presence of titanium nanoparticles and generation of amine groups after modification. Photocatalytic performance of nTi-loaded pristine and nanocomposite melt-electrospun filters was investigated by using methyl orange (MO) as a model compound. The decolorization experiments were carried out by varying initial dye concentration (10, 20, 40 mg/L), pH (2, 5, and 9), and loaded TiO2 amount (1 and 2 %). According to photocatalytic decolarization test results, nTi-loaded GA-treated pristine or nTi-PP nanocomposite fabric filter has better properties compared to GA-untreated group from point of photocatalytic efficiency, especially over 90 % decolorization efficiency at GA-treated pristine and nTi-PP composite PP fabrics. The complete decolarization of MO was observed at pH value of 5, photocatalyst concentration of 20 mg/L, and 1 % nTi-loading after 3 h. The results show that surface activated PP nonwovens, which is introduced Ti nanoparticles into and onto the structure, a good photocatalytic activity.

  20. Atomic layer deposition of amorphous oxygen-deficient TiO2-x on carbon nanotubes as cathode materials for lithium-air batteries

    Science.gov (United States)

    Yang, Jingbo; Ma, Dingtao; Li, Yongliang; Zhang, Peixin; Mi, Hongwei; Deng, Libo; Sun, Lingna; Ren, Xiangzhong

    2017-08-01

    The amorphous oxygen-deficient TiO2-x thin layer coated carbon nanotubes (CNTs) are synthesized by atomic layer deposition and employed as cathode materials for lithium-air battery. The cathode demonstrates high electrocatalytic activity toward electrode reactions, resulting from the introduction of oxygen-deficient TiO2-x into the nanocomposites. It is found that the intrinsically isotropic nature of amorphous TiO2 which a certain amount of Ti3.5+ and Ti3+ can improve the catalytic activity. Consequently, the battery with the corresponded CNT@TiO2-x cathode shows high discharge/charge capacities and good cycling performance, which the cyclic retention of more than 90 cycles are achieved, while with the pristine CNTs only 50 cycles are obtained. This study provides an approach to fabricate cathode materials for lithium-air battery and moreover clarifies the influence of oxygen vacancies of TiO2 on the electrochemical performance.

  1. Fabrication and characterization of uniform TiO2 nanotube arrays by sol–gel template method

    Indian Academy of Sciences (India)

    T Maiyalagan; B Viswanathan; U V Varadaraju

    2006-12-01

    TiO2 nanotubes have been synthesized by sol–gel template method using alumina membrane. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, UV absorption spectrum and X-ray diffraction techniques have been used to investigate the structure, morphology and optical properties of TiO2 nanotubes. SEM image showed that TiO2 nanotubes obtained were ordered and uniform. The diameter and length of the nanotubes were decided by the pore size and thickness of alumina template. Raman and XRD measurements confirmed the crystallinity and anatase phase of the TiO2 nanotubes. The optical absorption measurement of TiO2 nanotubes exhibits a blue shift with respect to that of the bulk TiO2 owing to the quantum size effect.

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

    Science.gov (United States)

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

    2016-09-15

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

  3. Fabrication of Mo+N-Codoped TiO2 Nanotube Arrays by Anodization and Sputtering for Visible Light-Induced Photoelectrochemical and Photocatalytic Properties

    Directory of Open Access Journals (Sweden)

    Min Zhang

    2013-01-01

    Full Text Available Mo,N-codoped TiO2 nanotube arrays (TNAs were fabricated by a two-step method consisting of electrochemical anodization and subsequent magnetron sputtering of Mo. The samples were characterized by scanning electron microscopy (SEM, X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS. The results showed that the Mo,N-codoped TiO2 nanotube arrays exhibited higher visible light absorbance and remarkably enhanced photocurrent density and photocatalytic activity compared with single N-doped TiO2. The highly efficient photoelectrochemical and photocatalytic activity is associated with the codoping effect between Mo and N, which plays a key role in producing new states, narrowing the bandgap, and reducing the recombination thereby effectively improving the visible light absorption and photocatalytic activity of TNAs.

  4. Fabrication of nanoporous TiO2 filters using organic-inorganic nanocomposites

    Science.gov (United States)

    Kaynar, Mehmet; Delpercio, Ryan; Yassitepe, Emre; Ozcan, Sadan; Shah, S.

    2013-03-01

    Nanoporous TiO2 filters with 50 nm mean pore size is synthesized by using commercial TiO2 nanoparticles and polyvinylpyrrolidone with an easy and low cost route that did not involve any solvent. Crystal's structure and surface morphologies are studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. X-ray photoelectron microscopy (XPS) is used to confirm the filtering process by analyzing pre- and post-filter affluent containing nanoparticles to simulate the filtration of micrometer (bacteria) and nanometer (virus) species. Greater than 85% filtering efficiency is obtained during the filtering of a mixture of water and 30 nm mean crystallite size of iron oxide nanoparticles. Supported by TUBITAK-BIDEB 2214-Abroad Research Scholarship program.

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

    Science.gov (United States)

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

    2009-11-01

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

  6. Ultra-High Speed Fabrication of TiO2 Photoanode by Flash Light for Dye-Sensitized Solar Cell.

    Science.gov (United States)

    Hwang, Hyun-Jun; Kim, Hak-Sung

    2015-07-01

    In this work, a new way to fabricate nanoporous TiO2 photoanode by flash light is demonstrated. TiO2 nanoparticles are sintered on FTO glass by flash light irradiation at room temperature in ambient condition, which is dramatically simple, ultrahigh speed and one-shot large area fabrication process compared to a conventional high temperature (120 °C) thermal sintering process. The effect of the flash light conditions (flash light energy, pulse numbers and pulse duration) on the nanostructures of sintered TiO2 layer, was studied and discussed using several microscopic and spectroscopic characterization techniques such as SEM, FT-IR, XRD and XPS. The sintered TiO2 photoanodes by flash light were used in DSSC and its performance were compared with that of DSSC fabricated by conventional thermal sintering process. It was found that a flash light sintered TiO2 photoanode has efficiency which is similar to that of the thermal sintered photoanode. It is expected that the newly developed flash light sintering technique of TiO2 nanoparticles would be a strong alternative to realize the room temperature and in-situ sintering of photoanode fabrication for outdoor solar cell fabrication.

  7. Fabrication of highly ordered TiO2 nanorod/nanotube adjacent arrays for photoelectrochemical applications.

    Science.gov (United States)

    Zhang, Haimin; Liu, Porun; Liu, Xiaolu; Zhang, Shanqing; Yao, Xiangdong; An, Taicheng; Amal, Rose; Zhao, Huijun

    2010-07-06

    This work reports a facile approach to fabricate a perpendicularly aligned and highly ordered TiO(2) nanorod/nanotube (NR/NT) adjacent film by directly anodizing a modified titanium foil. The titanium foil substrate was modified with a layer of crystalline TiO(2) film via a hydrothermal process in 0.05 M (NH(4))(2)S(2)O(8). The resultant NR/NT architecture consists of a highly ordered nanorod top layer that directly adjoins to a highly ordered nanotube array bottom layer. The thickness of the top nanorod layer was approximately 90 nm with average nanorod diameter of 22 nm after 20 min of anodization. The thickness of the bottom nanotube array layer was found to be ca. 250 nm after 20 min of anodization, having an average outer and inner tubular diameters of 120 and 80 nm, respectively. A broad implication of the method is that a simple modification to the substrate surface can lead to new forms of nanostructures. For as-anodized NR/NT samples, XRD analysis reveals that the nanorods are of anatase TiO(2) crystalline form while the nanotubes are amorphous. Anatase TiO(2) crystalline form of NR/NT film with high crystallinity can be obtained by thermally treating the as-anodized sample at 450 degrees C for 2 h in air. The resultant NR/NT film was used as a photoanode for photoactivity evaluation. Comparing with a nanotube array photoanode prepared by direct anodization of unmodified titanium foil, the NR/NT photoanode exhibits a unique feature of selective photocatalytic oxidation toward organics, which makes it very attractive to photocatalytic degradation of organic pollutants, sensing, and other applications.

  8. Fabrication of TiO2 nanorods/nanosheets photoelectrode on Ti mesh by hydrothermal method for degradation of methylene blue:influence of calcination temperature

    Science.gov (United States)

    Deng, Xiaoyong; Ma, Qiuling; Cui, Yuqi; Cheng, Xiuwen; Cheng, Qingfeng

    2017-10-01

    In the study, Using the strategy of hydrothermal reaction followed by annealing at different temperatures, TiO2 nanorods/nanosheets (NRs/NSs) photoelectrodes with diverse microcosmic morphologies and crystal structures were successfully fabricated. Moreover, all samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and Ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). Meanwhile the photoelectrochemical (PECH) properties were recorded through open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) curves. The photocatalytic (PC) activity of TiO2 NRs/NSs photoelectrodes were further measured by methylene blue (MB) degradation. Results suggest that the nanosheets possessed the width and thickness in the range of 100-400 and 10-20 nm, and the nanorods possessed the diameter in the range of around 10-20 nm, respectively. Also, the TiO2 NRs/NSs photoelectrode calcined at 500 °C exhibited the best proportion of both nanosheets and nanorods and higher photocatalytic activity (73.56%) than those of other TiO2 NRs/NSs photoelectrodes within 150 min under visible light illumination, which was ascribed to higher photoproduction electrons-holes (e/h+) pairs separation and visible light absorption. Therefore, the calcination temperature plays a significant role in altering the morphology and crystal structure of TiO2 NRs/NSs photoelectrode, and then enhanced PC performance.

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

    Science.gov (United States)

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

    2016-06-01

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

  10. TiO2纳米管阵列的制备与稀土掺杂改性研究%Fabrication and Modification of TiO2 Nanotube Arrays

    Institute of Scientific and Technical Information of China (English)

    兰宇卫; 周立亚; 童张法; 庞起; 王益林; 王祥科

    2011-01-01

    在水相中采用阳极氧化法制备了高度有序的TiO2纳米管阵列.探讨了稀土掺杂和染料敏化等因素对TiO2纳米管光电性能的影响,并对样品分别进行了X射线衍射(XRD)、扫描电镜(SEM)、紫外吸收光谱(UV-Vis)、荧光光谱(FS)和光电测试等性能测定.实验结果表明,通过稀土(Gd3+,La3+,Y3+)掺杂TiO2纳米管的光电性能都有所提升,其中Y3+掺杂的TiO2纳米管的光电效率和填充因子最高达到0.92%和0.59,Y3+掺杂后染料敏化TiO2纳米管太阳能光阳极的光电转换效率增加了近3.2倍.%The highly ordered and uniform TiO2 nanotube arrays were fabricated by anodic oxidation in aqueous solution.The effects of rare earth-doping and dye-sensitization on the photovoltaic properties of the TiO2 nanotube arrays were studied.These TiO2 samples were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) , UV-Vis absorption spectroscope (UV-Vis), fluorescence spectroscope (FS), and the photovoltaic properties were investigated.The results showed that the modification of rare-earth doping improved the photovoltaic properties of TiO2 nanotube arrays.The highest power conversion efficiency and filling factor of Y3+/TiO2 nanotube arrays achieved 0.92% and 0.59 respectively,and the dye-sensitization enhanced the power conversion efficiency of Y3+/ TiO2 nanotube arrays by 3.2 times.

  11. Electrospun TiO2 nanofibre-based gas sensors fabricated by AC electrophoresis deposition

    Indian Academy of Sciences (India)

    E Z Karimi; J Esmaeilzadeh; E Marzbanrad

    2015-02-01

    In this paper, gas sensing properties of the sensor based on titanium dioxide (TiO2) nanofibres are reported. These nanofibres were synthesized through electrospinning of polyvinyl pyrrolidone (PVP) / titanium tetra isopropoxide. Calcination of the obtained amorphous PVP/TiO2 nanofibres resulted in nanofibres of TiO2 with the same morphology. In this step, scanning electron microscopy and X-ray diffraction were applied in order to analyse these nanofibres. Then, nanofibres of TiO2 were deposited selectively by AC electrophoretic deposition on interdigitated electrodes and exposed to different concentrations of NO2 (8–50 p.p.m.) at 450–550°C. Gas sensing measurements illustrated that this sensor had adequate response to target gas at 450°C. The maximum response of gas sensors, (the ratio of sensor resistances $S = R_{\\text{gas}}/R_{\\text{N2}}$), achieved was around 30 for 50 p.p.m. NO2 at 450°C.

  12. Fabrication of a TiO2-BDD heterojunction and its application as a photocatalyst for the simultaneous oxidation of an azo dye and reduction of Cr(VI).

    Science.gov (United States)

    Yu, Hongbin; Chen, Shuo; Quan, Xie; Zhao, Huimin; Zhang, Yaobin

    2008-05-15

    A TiO2-boron doped diamond (TiO2-BDD) heterojunction was employed as a photocatalyst to simultaneously oxidize an azo dye C.I. reactive yellow 15 (RY15) and reduce hexavalent chromium (Cr(VI)). This heterojunction was fabricated first by depositing a BDD film on a Ti sheet in a hot filament chemical vapor deposition reactor, followed by covering a layer of TiO2 in a metal-organic chemical vapor deposition system. The morphology of this heterojunction was characterized by using a scanning electron microscope (SEM). X-ray diffraction (XRD), Raman spectroscopy, and current-voltage (I-V) measurement were used to characterize its structures. Additionally, the characterization of surface photovoltage showed that the TiO2-BDD heterojunction exhibited a higher photovoltage response and a better ability for charge separation than the photocatalyst of TiO2 directly deposited on a Ti sheet (TiO2-Ti). The photocatalytic experiments revealed that the kinetic constants for the oxidation of RY15 and the reduction of Cr(VI) were, respectively, increased by 85 and 71% when the photocatalyst of TiO2-Ti was replaced by the TiO2-BDD heterojunction. Meanwhile, a significant synergy was confirmed in the simultaneous oxidation of RY15 and reduction of Cr(VI). The enhanced photocatalytic ability of the TiO2-BDD composite could be attributed to the heterojunction. The possible photocatalytic mechanism was also discussed.

  13. Simple fabrication of N-doped mesoporous TiO2 nanorods with the enhanced visible light photocatalytic activity.

    Science.gov (United States)

    Zhou, Xiufeng; Lu, Juan; Jiang, Jingjing; Li, Xiaobin; Lu, Mengna; Yuan, Guotao; Wang, Zuoshan; Zheng, Min; Seo, Hyo Jin

    2014-01-16

    N-doped mesoporous TiO2 nanorods were fabricated by a modified and facile sol-gel approach without any templates. Ammonium nitrate was used as a raw source of N dopants, which could produce a lot of gasses such as N2, NO2, and H2O in the process of heating samples. These gasses were proved to be vitally important to form the special mesoporous structure. The samples were characterized by the powder X-ray diffraction, X-ray photoelectron spectrometer, nitrogen adsorption isotherms, scanning electron microscopy, transmission electron microscopy, and UV-visible absorption spectra. The average length and the cross section diameter of the as-prepared samples were ca. 1.5 μm and ca. 80 nm, respectively. The photocatalytic activity was evaluated by photodegradation of methylene blue (MB) in aqueous solution. The N-doped mesoporous TiO2 nanorods showed an excellent photocatalytic activity, which may be attributed to the enlarged surface area (106.4 m2 g-1) and the narrowed band gap (2.05 eV). Besides, the rod-like photocatalyst was found to be easy to recycle.

  14. Chemical assembly of TiO2 and TiO2@Ag nanoparticles on silk fiber to produce multifunctional fabrics.

    Science.gov (United States)

    Li, Guohong; Liu, Hong; Zhao, Hongshi; Gao, Yuqiang; Wang, Jiyang; Jiang, Huaidong; Boughton, R I

    2011-06-01

    A carefully designed surface modification technique for the manufacture of multifunctional silk textile nanocomposite materials is successfully developed by the functionalization of silk with TiO(2) and TiO(2)@Ag nanoparticles (NPs). The NPs are assembled onto a silk substrate through covalent linkages, including enediol ligand-metal oxide bonding, resin dehydration and the acylation of silk. Owing to the strong chemical bonding, silk fibroin fabric (SFF) and the NPs form a stable composite system. The functionalized SFF, especially TiO(2)@Ag NP-functionalized SFF are endowed with remarkable UV protection properties, and an efficient anti-bacterial capability toward Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Furthermore, the nearly total photodegradation of methylene orange (MO) under UV illumination illustrates that functionalized SFF possesses high photocatalytic and self-cleaning capability. This multifunctional silk material satisfies the market demand for natural "smart" products, and is a promising practical material for use in the textile industry, hospital sterilization and environmental cleanup.

  15. Fabrication of TiO2 Nanotube Thin Films and Their Gas Sensing Properties

    Directory of Open Access Journals (Sweden)

    Yongxiang Li

    2009-01-01

    Full Text Available The fabrication process and the growth mechanism of titanium/titania nanotubes prepared by anodization process is reviewed, and their applications in the fields of dye sensitized solar cells, photocatalysts, electrochromic devices, gas sensors, and biomaterials are presented. The anodization of Ti thin films on different substrates and the growth process of anodic titanium oxide are described using the current-time curves. Special attention is paid on the influences of the initial film smoothness on the resulted nanoporous morphologies. The “threshold barrier layer thickness model” is used to discuss the growth mechanism. As a case study for gas sensing, anodized highly ordered TiO2 nanotube arrays and nanoporous thin films that show porous surface with an average diameter of 25 nm and interpore distance of 40 nm were prepared. Gas sensors based on such nanotube arrays and nanoporous thin films were fabricated, and their sensing properties were investigated. Excellent H2 gas sensing properties were obtained for sensors prepared from these highly ordered TiO2 nanotube arrays, which present stable response even at a low operating temperature of 90°C. Based on our experimental results, “H-induced O2− desorption” mechanism was used for explaining the hydrogen gas sensing mechanism.

  16. A novel TiO2 tape for fabricating dye-sensitized solar cells on universal conductive substrates.

    Science.gov (United States)

    Shen, Jie; Cheng, Rui; Chen, Yiwei; Chen, Xiaohong; Sun, Zhuo; Huang, Sumei

    2013-12-26

    The present paper describes a new method for manufacturing large scale, stable, transportable, and designable nanostructured porous TiO2 tapes on various substrates for use in photoelectrochemical cells. The method involves predeposition of TiO2 strips on the fluorine doped tin oxide (FTO) glass by screen-printing method, peeling off TiO2 strips from the substrate by a novel laser-assisted lift-off technique, sintering the formed TiO2 tapes at 500 °C for 15 min, and compressing the sintered TiO2 tapes on different conductive substrates with a low pressure rolling press to form mechanically stable, electrically conducting, porous nanostructured TiO2 electrodes at room temperature. Photoelectrochemical characteristics of the resulted electrodes are presented. Dye-sensitized solar cells (DSSCs) with the as-fabricated TiO2 photoanodes on PET-ITO and FTO glass achieved a conversion efficiency of 4.2% and 6.2%, respectively. The potential use of this new manufacturing method in future DSSC applications is discussed.

  17. Effect of rutile TiO2 on the photocatalytic performance of g-C3N4/brookite-TiO2-xNy photocatalyst for NO decomposition

    Science.gov (United States)

    Li, Huihui; Wu, Xiaoyong; Yin, Shu; Katsumata, Kenichi; Wang, Yuhua

    2017-01-01

    Novel g-C3N4/rutile-brookite TiO2-xNy composite photocatalysts were fabricated through a facile solvothermal approach. The effect of rutile phase TiO2 with brookite TiO2 and g-C3N4 on the photocatalytic activity of g-C3N4/nitrogen-doped TiO2 composite was studied. The photocatalytic performance of the photocatalyst was evaluated by measuring the degradation of NO gas under visible and UV light irradiation. It is suggested that g-C3N4/rutile-brookite TiO2-xNy forms a Z-scheme photocatalytic system, which shows improvement on the photocatalytic activity than that of g-C3N4/single brookite TiO2-xNy. By importing rutile phase TiO2-xNy, the photogenerated electrons can efficiently transfer from rutile TiO2 to g-C3N4, which results in the separation of electron and hole pairs, enhancing the photocatalytic ability. However, single brookite TiO2-xNy can not remove the photogenerated electrons efficiently and the photocatalytic performances of composites decrease with g-C3N4 amount increase.

  18. 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.

  19. Bacteria Adherence Properties of Nitrogen-Doped TiO2 Coatings by Plasma Surface Alloying Technique

    Science.gov (United States)

    Wang, Hefeng; Tang, Bin; Li, Xiuyan; Fan, Ailan

    Titanium nitride coatings on 316L stainless steel (S. S) were obtained by plasma surface alloying technique. Nitrogen-doped titanium dioxide (TiO2-xNx) was synthesized by oxidative annealing the resulted TiNx coatings in air. The reference TiO2 samples were also prepared by oxidation of sputtered Ti coatings. The as-prepared coatings were characterized by X-ray diffraction, glow discharge optical emission spectrometer (GDOES), scanning electron microscopy, X-ray hotoelectron spectroscopy and UV-Vis spectrophotometry, respectively. The bacteria adherence property of the TiO2-xNx coatings on stainless steel on the oral bacteria Streptococcus Mutans was investigated and compared with that of stainless steel by fluorescence microscopy. The mechanism of the bacteria adherence was discussed. The results show that the TiO2-xNx coatings are composed of anatase crystalline structure. SEM measurement indicates a rough surface morphology with three-dimensional homogenous protuberances after annealing treatment. Optical properties reveal an extended tailing of the absorption edge toward the visible region due to nitrogen presence. The band gap of the N-doped sample is reduced from 2.29 eV to 1.90 eV compared with the pure TiO2 one. Because of the different roughness and microstructure, the TiO2-xNx coatings inhibit the bacteria adherence.

  20. Fabrication of a TiO2@porphyrin nanofiber hybrid material: a highly efficient photocatalyst under simulated sunlight irradiation

    Science.gov (United States)

    La, Duong Duc; Rananaware, Anushri; Phuong Nguyen Thi, Hoai; Jones, Lathe; Bhosale, Sheshanath V.

    2017-03-01

    The solar spectrum consists of 8% UV radiation, while 45% of solar energy is from visible light. It is therefore desirable to fabricate a hybrid material which is able to harvest energy from a wide range of photons from the sun for applications such as solar cells, photovoltaics, and photocatalysis. In this study we report on the fabrication of a TiO2@porphyrin hybrid material by surfactant-assisted co-assembly of monomeric porphyrin molecules with TiO2 nanoparticles. The obtained TiO2@porphyrin composite shows excellent integration of TiO2 particles with diameters of 15–30 nm into aggregated porphyrin nanofibers, which have a width of 70–90 nm and are several µm long. SEM, XPS, XRD, FTIR, UV–Vis and fluorescence spectroscopy were employed to characterize the TiO2@TCPP hybrid material. This material exhibits efficient photocatalytic performance under simulated sunlight, due to synergistic photocatalytic activities of the porphyrin aggregates in visible light and TiO2 particles in the UV region. A plausible mechanism for photocatalytic degradation is also proposed and discussed.

  1. A SnOx-brookite TiO2 bilayer electron collector for hysteresis-less high efficiency plastic perovskite solar cells fabricated at low process temperature.

    Science.gov (United States)

    Kogo, Atsushi; Ikegami, Masashi; Miyasaka, Tsutomu

    2016-06-21

    Thin plastic film-based CH3NH3PbI3-xClx perovskite solar cells were fabricated at low process temperature using a bilayer comprising an amorphous SnOx and mesoporous brookite TiO2 as electron collectors. Void-less high quality heterojunction structures achieve hysteresis-less photovoltaic performance with a power conversion efficiency as high as 13.4% and mechanical stability against cyclic bending.

  2. ANALISA DIFRAKSI SINAR X TiO2 DALAM PENYIAPAN BAHAN SEL SURYA TERSENSITISASI PEWARNA

    Directory of Open Access Journals (Sweden)

    Erna Hastuti

    2012-03-01

    Full Text Available Upaya pengembangan sel surya organic sebagai solusi alternatif krisis energi dunia merupakan hal yang perlu dan penting untuk dilakukan, mengingat sumber energi sel surya yang melimpah dan terbarukan. Salah satu bahan penyusun sel surya adalah semikonduktor TiO2 sebagai transport pembawa muatan. Struktur kristal yang cocok digunakan adalah anatase karena memiliki ukuran pori yang kecil dan bersifat fotoaktif. Pada penelitian ini dikarakterisasi bahan TiO2 yang akan digunakan sebagai bahan semikonduktor dalam sel surya pewarna menggunakan difraksi sinar X dan dianalisa menggunakan program match. Dari hasil penelitian didapatkan bahwa TiO2 memiliki  fase anatase dan ukuran kristalnya 2.6 nm. Ukuran kristal yang berukuran nano dapat memaksimalkan penyerapan pewarna sehingga dapat meningkatkan efisiensi sel surya.

  3. Hierarchical nanostructures of copper(II) phthalocyanine on electrospun TiO(2) nanofibers: controllable solvothermal-fabrication and enhanced visible photocatalytic properties.

    Science.gov (United States)

    Zhang, Mingyi; Shao, Changlu; Guo, Zengcai; Zhang, Zhenyi; Mu, Jingbo; Cao, Tieping; Liu, Yichun

    2011-02-01

    In the present work, 2,9,16,23-tetranitrophthalocyanine copper(II) (TNCuPc)/TiO(2) hierarchical nanostructures were successfully fabricated by a simple combination method of electrospinning technique and solvothermal processing. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), UV-vis diffuse reflectance (DR), Fourier transform infrared spectrum (FT-IR), X-ray photoelectron spectroscopy (XPS), and thermal gravimetric and differential thermal analysis (TG-DTA) were used to characterize the as-synthesized TNCuPc/TiO(2) hierarchical nanostructures. The results showed that the secondary TNCuPc nanostructures were not only successfully grown on the primary TiO(2) nanofibers substrates but also uniformly distributed without aggregation. By adjusting the solvothermal fabrication parameters, the TNCuPc nanowires or nanoflowers were facilely fabricated, and also the loading amounts of TNCuPc could be controlled on the TNCuPc/TiO(2) hierarchical nanostructural nanofibers. And, there might exist the interaction between TNCuPc and TiO(2). A possible mechanism for the formation of TNCuPc/TiO(2) hierarchical nanostructures was suggested. The photocatalytic studies revealed that the TNCuPc/TiO(2) hierarchical nanostructures exhibited enhanced photocatalytic efficiency of photodegradation of Rhodamine B (RB) compared with the pure TNCuPc or TiO(2) nanofibers under visible-light irradiation.

  4. TiO2/Polyester Non-woven Fabrics as a Kind of Photocatalyst for the Degradation of Formaldehyde Gas

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The feasibility of photocatalytic degradation of the formaldehyde gas by titanium dioxide (TiO2)/polyester non-woven fabrics was studied. The effects of parameters such as the concentration of TiO2 solution, pH value, and drying temperature on the photocatalytie degradation of the formaldehyde gas were also studied. The results showed that the photodegradation efficiency of the formaldehyde gas increased rapidly with the increasing of the concentration of TiO2 solution up to 15g/L, but when the concentration was in excess of 15 g/L, the photodegradation efficiency decreased gradually and fluctuated due to light obstruction and disperse state of TiO2. Adjusting the pH value in the solution, the efficiency of photocatalytic degradation of the formaldehyde gas could be improved. The mechanisms of the reaction and the role of the additives were also investigated. After 42hours, TiO2/ polyester non-woven fabric showed no significant loss of the photocatalytic activity. Ke ywords : formaldehyde, photocatal ytic degradation,titanium dioxide, polyester non-voven fabric.

  5. Photoelectric characteristics of natural pigments self-assembly fabricated on TiO2/FTO substrate.

    Science.gov (United States)

    Su, Yen Hsun; Teoh, Lay Gaik; Lee, Jian-Hong; Tu, Sheng-Lung; Hon, Min Hsiung

    2009-02-01

    Natural pigment can act as an inexpensive and biologically-friendly dye, which is fabricated on a TiO2/FTO substrate. Natural pigments promote the efficiency of the photoelectric conversion in water-based DSSC with the aqueous electrolyte of the Ce+4/+3 system. The open-circuit voltage (Voc) of natural pigment in water-based DSSC is 0.640 V. The short-circuit current (Isc) of natural pigment in water-based DSSC is 0.658 mA/cm2. The efficiency of the photoelectric conversion in water-based DSSC of natural pigment is up to 0.131%. The natural pigments in DSSC are potentially applicable to turning solar energy into environmentally-friendly energy.

  6. TiO2/Au纳米棒阵列的制备及其光催化性能%Fabrication of a TiO2/Au Nanorod Array for Enhanced Photocatalysis

    Institute of Scientific and Technical Information of China (English)

    路莹; 陈硕; 全燮; 于洪涛

    2011-01-01

    采用电沉积和旋转涂膜相结合的方法成功制备了高度有序的TiO2/Au纳米棒阵列催化剂.扫描电镜和透射电镜结果表明,TiO2薄膜均匀地包覆在Au纳米棒的表面,形成核壳型的一维阵列结构.X射线衍射分析表明所获得TiO2为(101)晶面优先生长的锐钛矿晶相.紫外-可见漫反射光谱显示,由于Au和TiO2间肖特基结的存在造成吸收红移,Au纳米棒表面的等离子共振效应导致400~800 nm间出现吸收峰.在紫外光催化降解罗丹明B反应中,TiO2/Au纳米棒阵列催化剂表现出优异的催化活性,其动力学常数分别为TiO2和TiO2/Au膜的2.0和1.3倍.这主要归结于Au与TiO2间的肖特基结和一维阵列结构所带来的大的比表面积、宽的光响应范围和有效的光生载流子分离与传递.%A highly ordered TiO2/Au nanorod array was successfully fabricated by direct current electrodeposition and subsequent spin-coating.Scanning electron microscopy and transmission electron microscopy images revealed that the TiO2 film completely covered the surface of the Au nanorods,which resulted in TiO2 shell Au core nanorods.X-ray diffraction patterns revealed that the TiO2 film was anatase with preferential orientation in the (101) plane.UV-Vis diffuse reflectance spectra showed a shift in the absorption edge toward the visible region because of the formation of a Schottky junction between Au and TiO2.A new absorption peak that ranged from 400 to 800 nm appeared because of the localized surface plasmon resonance of the Au nanorod arrays.For the photocatalytic degradation of rhodamine B under UV light irradiation,the TiO2/Au nanorod array exhibited excellent photocatalytic activity and its kinetic constant was 2.0 times that of pristine TiO2 and 1.3 times that of a TiO2/Au film.The enhanced photocatalysis was attributed to the high surface volume ratio,an improved UV light response,efficient separation,and the convenient migration of photogenerated charge

  7. Fabrication and characterization of TiO2 coated cone shaped nano-fiber pH sensor

    Science.gov (United States)

    Pathak, A. K.; Bhardwaj, V.; Gangwar, R. K.; De, M.; Singh, V. K.

    2017-03-01

    In the present paper a novel cone shaped nano-fiber (CSNF) pH sensor using multi-mode fiber (MMF) has been fabricated and demonstrated. Three different pH indicators, chlorophenol red, bromothymol blue and cresol red with precursor tetraethyl orthosilicate (TEOS) have been used for fabrication of pH sensing layer. A significant enhancement in sensing properties of pH sensor with TiO2 thin film has been observed. The pH sensor with TiO2 thin film shows the quite high sensitivity (1.16 dBm/pH) as compared to sensor with simple pH coating (0.81 dBm/pH) at 1550 nm with a good linear response. Moreover, the sensor with TiO2 film exhibits fast response time of ∼ 25 s for pH values ranging from 4 to 11 with excellent stability and durability.

  8. Fabrication of TiO2/Ag2O heterostructure with enhanced photocatalytic and antibacterial activities under visible light irradiation

    Science.gov (United States)

    Liu, Bingkun; Mu, Lilong; Han, Bing; Zhang, Jingtao; Shi, Hengzhen

    2017-02-01

    TiO2/Ag2O heterostructure prepared by a facile in situ precipitation route was used as an effective visible light-driven photocatalyst for degradation of methylene blue (MB) and inactivation of E. coli. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) revealed that Ag2O nanoparticles were well distributed on the surface of TiO2 microspheres. The TiO2/Ag2O composite with optimal mass ratio of TiO2 and Ag2O displayed extremely good photodegradation ability and antibacterial capability under visible light irradiation, which was mainly ascribed to the synergistic effect between Ag2O and TiO2, including highly dispersed smaller Ag2O particles, increased visible light absorption and efficient separation of photo-induced charge carriers. Meanwhile, the roles of the radical species in the photocatalysis process were investigated. Our results showed that the TiO2/Ag2O could be used as a dual functional material in water treatment of removing the organic pollutant and killing the bacterium at the same time.

  9. Fabrication of 3 D Mesoporous Black TiO2 /MoS2 /TiO2 Nanosheets for Visible-Light-Driven Photocatalysis.

    Science.gov (United States)

    Liu, Xuefeng; Xing, Zipeng; Zhang, Hang; Wang, Wenmei; Zhang, Yan; Li, Zhenzi; Wu, Xiaoyan; Yu, Xiujuan; Zhou, Wei

    2016-05-23

    A novel 3 D mesoporous black TiO2 (MBT)/MoS2 /MBT sandwich-like nanosheet was successfully fabricated using a facile mechanochemical process combined with an in situ solid-state chemical reduction approach, followed by mild calcination (350 °C) under an argon atmosphere. The MBT/MoS2 /MBT exhibits a 3 D sandwich-like nanosheet structure and heterojunctions are formed at the interfaces between MoS2 and black TiO2 . The significantly narrowed band gap of MBT/MoS2 /MBT is attributed to the introduction of MoS2 and the formed Ti(3+) species in the frameworks. The visible-light photocatalytic degradation rate of methyl orange and the hydrogen production rate are as high as 89.86 % and 0.56 mmol h(-1)  g(-1) , respectively. The introduction of MoS2 and Ti(3+) in the frameworks favors the visible-light absorption and the separation of photogenerated charges, and the 3 D sandwich-like heterojunction structure facilitates the transfer of photogenerated charges.

  10. Fabrication of dye-sensitized solar cell (DSSC) using different particle sizes of TiO2 deposited via nano-particle deposition system (NPDS).

    Science.gov (United States)

    Kim, Yang-Hee; Kim, Kwang-Su; Lee, Jin-Woong; Kim, Min-Saeng; Choi, Jung-Oh; Ahn, Sung-Hoon; Lee, Caroline Sunyong

    2012-04-01

    TiO2 layers were fabricated using a nano-particle deposition system (NPDS) on transparent conductive oxide (TCO) glass for dye sensitized solar cells (DSSCs). Conventionally, TiO2 paste for working electrodes has been fabricated using paste type methods. The fabricated paste composed of a mixture of nano-sized TiO2 powders, binders and solutions is then painted on TCO glass. After drying, the TiO2 layer on TCO glass is sintered to make a path for electron transfer. TiO2 layers formed by this paste type method require numerous steps, which can be time consuming. In this study, TiO2 powders were sprayed directly on TCO glass using NPDS in order to simplify the fabrication steps. To improve porosity and produce scattering layers, commercial nanocrystalline TiO, powders with different sizes were alternately deposited. Moreover, powders with different sizes were mixed and deposited on the TCO glass. The results indicate that the DSSCs with a TiO2 layer composed of different particle sizes had better cell performance than the cells assembled with single-sized TiO2 particles. Therefore, this study shows that a dry TiO2 coating process is possible for DSSC fabrication to improve its cell efficiencies, and this method can easily be applied on flexible substrates since NPDS is a room-temperature deposition process.

  11. The Effects of TiO2 Nanoparticles over Time on the Physical and Mechanical Properties of White Cotton Fabrics and Fabrics Died with Reactive Dyes

    Directory of Open Access Journals (Sweden)

    Mohammadreza Mirkhan

    2016-05-01

    Full Text Available Today, nano particles of titanium are used mainly in the textile industry. Examples of it can be named as cultivation of nano particles of titanium on polyester cotton fabrics, with features as white-washing, self- cleaning and also the effect of TiO2 on the dyed textiles with natural dyes as well as the effect of commodities reactive to increase the brightness and transparency of them. But, as this procedure has the added benefits, it will sure have some disadvantages and thus, the aim of this project is to study the effects of nano- TiO2 in the passage of time, at different times over the physical and mechanical properties of checked cotton fabrics. And even the study of dyed fabrics with natural dyes in reactive so that it can examine the beneficial and harmful effects of the degradation and also check the results on the Cotton Nano TiO2 Fabric.

  12. 制备TiO2-xNx薄膜陶瓷托槽的抗菌性能%TiO2-xNx thin filmson ceramic bracket surfaces:preparation and antibiotic performance

    Institute of Scientific and Technical Information of China (English)

    王建卫; 王宇; 车远倩; 朱博武; 曹宝成

    2016-01-01

      结果与结论:①TiO2-xNx薄膜为锐钛矿型,结构均匀致密,随着薄膜厚度的增加,X射线衍射峰表现为增强趋势;②厚度最高薄膜最终附着力为18.37 N,说明薄膜与托槽具有较好的附着力,可承受在口腔应用中所受到的摩擦;③镀膜后,厚度最高薄膜托槽的色泽均有所变化,但变化较小,不至于影响陶瓷托槽原有的美观特性;④TiO2-xNx薄膜陶瓷托槽对白色念珠菌、变形链球菌均有一定的抗菌性能,且随着薄膜厚度的增加抗菌性能逐渐增强,对变形链球菌的抗菌效果更明显;⑤结果表明,TiO2-xNx薄膜陶瓷托槽在不影响美观的同时,对常见口腔致龋菌和条件致病菌具有较高的抗菌作用,且与托槽具有较好的附着力。%BACKGROUND:Enamel demineralization has been plaguing doctors and patients in the fixed orthodontic treatment, so we attempt to seek an effective method of reducingitsincidence. OBJECTIVE:To prepare TiO2-xNx thin filmsat different thicknesses on the ceramic bracket surface by sol-gel method folowed by detection of antibiotic performance. METHODS:TiO2-xNx thin films at different thicknesses were prepared on the ceramic bracket surface by sol-gel method. The crystal structure, surface morphology and attachment force of these thin films were analyzed by X-ray diffraction, scanning electron microscope and multi-function material surface tester, respectively. The color changes of ceramic brackets before and after coating were evaluated through German VITA Easyshade Advance 4.0 photoelectric color comparator. Antibiotic performance of the ceramic bracket coated with TiO2-xNx thin film forCandida albicansandStreptococcus mutanswas evaluated by the flat colony counting method. RESULTS AND CONCLUSION:The prepared TiO2-xNx thin film was anatase type, which had uniform and compact structure, and its X-ray diffraction peaks were elevated with the increase of film thickness. The

  13. Growth and characterization of rutile TiO2 nanorods on various substrates with fabricated fast-response metal-semiconductor-metal UV detector based on Si substrate

    Science.gov (United States)

    Selman, Abbas M.; Hassan, Z.

    2015-07-01

    Rutile-phase titanium dioxide nanorods (NRs) were synthesized successfully on p-type silicon (Si) (1 1 1), c-plane sapphire (Al2O3), glass coated with fluorine-doped tin oxide (FTO), glass, and quartz substrates via chemical bath deposition method. All substrates were seeded with a TiO2 seed layer synthesized with a radio frequency reactive magnetron sputtering system prior to NRs growth. The effect of substrate type on structural, morphological, and optical properties of rutile TiO2 NRs was studied. X-ray diffraction, Raman spectroscopy, and field-emission scanning electron microscopy analyses showed the tetragonal rutile structure of the synthesized TiO2 NRs. Optical properties were examined with photoluminescence (PL) spectroscopy of the grown rutile NRs on all substrates, with the spectra exhibiting one strong ultraviolet emission peak intensity compared with broad visible peak. The optimal sample of rutile NRs was grown on Si substrate. Thus, a fast-response metal-semiconductor-metal ultraviolet (UV) detector was fabricated. Upon exposure to 365 nm light (2.3 mW/cm2) at 5 V bias, the device displays 2.62 × 10-5 A photocurrent, and the response and recovery times are calculated as 18.5 and 19.1 ms, respectively. These results demonstrate that the fabricated high-quality photodiode is a promising candidate as a low-cost UV photodetector for commercially integrated photoelectronic applications.

  14. Fabrication of dye-sensitized solar cells with multilayer photoanodes of hydrothermally grown TiO$_2$ nanocrystals and P25 TiO$_2$ nanoparticles

    Indian Academy of Sciences (India)

    MAZIAR MARANDI; MAHBOUBEH NAEIMI SANI SABET; FARZANEH AHMADLOO

    2016-10-01

    TiO$_2$ nanocrystals (NCs) with sizes around 20 nm were synthesized by hydrothermal method in acidic autoclaving pH. The hydrothermally grown TiO$_2$ NCs and P25 TiO$_2$ nanoparticles (NPs) were used in the preparationof two different pastes using different procedures. These pastes with different characteristics were separately deposited on FTO glass plates to form multilayer photoanodes of the dye-sensitized solar cells. The aim of this study was to search how a thin sub-layer of the hydrothermally grown TiO2 NCs in the photoanodes could improve the efficiency of TiO$_2$ P25-based solar cells. The highest efficiency of 6.5% was achieved for a cell with a photoanodecomposed of one transparent sub-layer of hydrothermally grown TiO$_2$ NCs and two over-layers of P25 NPs. Higher energy conversion efficiencies were also attainable using two transparent sub-layers of hydrothermally grown TiO$_2$ NCs. In this case, an efficiency of 7.2% was achieved for a cell with a photoelectrode made of one over-layer of P25 TiO$_2$ NPs. This could show an increase of about 30% in the efficiency compared to the similar cell with a photoanode made of two layers of hydrothermally grown TiO2 NCs.

  15. THE APPLICATION AND CHARACTERIZATION OF GRAPHENE DECORATED WITH TiO2 –Fe (1%-N ON COTTON FABRICS

    Directory of Open Access Journals (Sweden)

    DUMITRESCU Iuliana

    2017-05-01

    Full Text Available Doped TiO2/graphene nanocomposites are studied due to their capacity to absorb the visible rays and large applicability in photo-catalytic applications. In this paper, we summarize our experiments on the development of photocatalytic fabrics based on deposition of doped TiO2/graphene nanocomposites by ultrasound method. We have investigated the surface morphology by scanning electron microscopy (SEM and elemental composition was determinate through EDX. Other information were obtained from electrical resistivity analysis measured on Prostat PRS-801 instrument, evaluation of the cotton fabrics wettability by measuring the contact angle on a VCA Optima instrument and evaluation of the photo-catalytic properties of the treated fabrics under solar and visible light (Xenotest by measuring the trichromatic coordinates of the treated and untreated textile materials. The results demonstrated that the ultrasound is an effective method to deposit nanoparticles on textile materials and that the uniform dispersion of TiO2- graphene composites depends on sonication parameters. Also, the treatment used on textile materials doesn’t improve the electrical properties of the knit. The results obtain after evaluation of the photo-catalytic activity by photo degradation of methylene blue under visible and solar light show the performance of the developed fabrics and also that the photo-catalytic activity is high under visible light and solar light.

  16. Fabrication of TiO2/ZnS nanocomposites for solar energy mediated photocatalytic application

    Science.gov (United States)

    Prasannalakshmi, P.; Shanmugam, N.

    2017-03-01

    In the present work, we demonstrate the photocatalytic properties of nanosized TiO2, and different levels of ZnS-loaded TiO2/ZnS composites, for the degradation of the organic dyes brilliant green (BG), and methylene blue (MB) under solar light irradiation. For this process, TiO2 and the composites were synthesized by a sol-gel method. Further, the prepared products were subjected to structural, optical, and morphological characterizations. The results of the photocatalytic activity imply that for the samples studied, TiO2 loaded with an optimum level of zinc (0.25 M), and sulfur (0.5 M) is better able to actively degrade both BG and MB, due to its enhanced BET surface area, reduced band gap, and low charge transfer resistance.

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

    Science.gov (United States)

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

    2015-01-01

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

  18. Fabrication of TiO2-strontium loaded CaSiO3/biopolymer coatings with enhanced biocompatibility and corrosion resistance by controlled release of minerals for improved orthopedic applications.

    Science.gov (United States)

    Raj, V; Raj, R Mohan; Sasireka, A; Priya, P

    2016-07-01

    Titanium dioxide (TiO2) arrays were fabricated on Ti alloy by anodization method. Synthesis of CaSiO3 (CS) and various concentrations (1X-5X) of Sr(2+) substitutions in CS coatings on TiO2 substrate was achieved through an electrophoretic deposition technique. Fast release of mineral ions from implant surface produce over dosage effect and it is a potential hazardous factor for osteoblasts. So, in order to prevent the fast release of minerals, biopolymer coating was applied above the composite coatings. The coatings were characterized by FTIR, XRD, FE-SEM and EDX techniques. The mechanical, anticorrosion, antimicrobial properties and biocompatibility of the coatings were evaluated. Studies on the mechanical properties indicate that the addition of Sr(2+) and biopolymer increase the hardness strength of the coatings. The metal ion release from the coatings was studied by ICP-AES. The electrochemical properties of the coatings were studied in Ringer's solution, in which CS-3X/Chi-PVP coating on TiO2 exhibits good anticorrosion property and high resistivity against Escherichia coli and Staphylococcus aureus compared to CS-3X coating on TiO2. In vitro cell experiments indicate that osteoblasts show good adhesion and high growth rates for CS-3X/Chi-PVP coated TiO2 substrate, indicating that the surface cytocompatibility of CS-3X/Chi-PVP coated TiO2 substrate is significantly improved by the controlled release of mineral ions. In conclusion, the surface modification of TiO2/CS-3X/Chi-PVP coated titanium is a potential candidate for implant coating.

  19. Fabrication of regular TiO2 nanoporous films derived by combining nanoimprint technique with sol-gel method.

    Science.gov (United States)

    Zhong, Peng; Que, Wenxiu; Zhang, Jin

    2010-11-01

    In this paper, honeycomb-like regular TiO2 nanoporous films deposited on different substrates including ITO glass and silicon wafer are fabricated by combining a nanoimprint technique with a sol-gel method. A novel soft polymer mold containing a thin layer of polymethylmethacrylate and a thicker layer of polydimethylsiloxane, which is obtained from an anodic aluminum oxide template, is carried out for the nanoimprint process. TiO2 precursor solution prepared by the sol-gel processing is used as the nanoimprinted material. After imprinting, the polydimethylsiloxane back layer is easily peeled off before the polymethylmethacrylate mold is chemically removed to avoid any demolding problem. The SEM images show that the honeycomb-like regular nanostructure of the initial anodic aluminum oxide template can be preserved completely on TiO2 via this method, and the XRD results indicate that there is a crystalline transition from amorphous to anatase of TiO2 after 450 degrees C heat treatment.

  20. Structural and photocatalytic properties of TiO2 films fabricated on silicon substrates by MOCVD method

    Institute of Scientific and Technical Information of China (English)

    YANG Jia-long; LI Ying; WANG Fu; ZUO Liang; Gu-Chul Yi; Wong Yong Choi

    2005-01-01

    Silicon(111) and Silicon(100) were employed for fabrication of TiO2 films by metal organic chemical vapor deposition(MOCVD).Titanium(Ⅳ) isopropoxide(Ti[O(C3H7)4]) was used as a precursor. The as-deposited TiO2 films were characterized with FE-SEM, XRD and AFM. The photocatalytic properties were investigated by decomposition of aqueous Orange Ⅱ. And UV-VIS photospectrometer was used for checking the absorption characteristics and photocatalytic degradation activity. The crystalline and structural properties of TiO2 film had crucial influences on the photodegradation efficiency. For MOCVD in-situ deposited films on Si substrates, the photoactivities varied following a shape of "M": at lower(350℃), middle(500℃) and higher(800℃) temperature of deposition, relative lower photodegradation activities were observed. At 400℃ and 700℃ of deposition, relative higher efficiencies of degradation were obtained, because one predominant crystallite orientation could be obtained as deposition at the temperature of two levels, especially a single anatase crystalline TiO2 film could be obtained at 700℃.

  1. Fabrication of TiO2 Cathodes by Anodic Oxidation for Hydrogen Generation from Electrolysis of Water

    Directory of Open Access Journals (Sweden)

    *İ. Koyuncu

    2014-09-01

    Full Text Available In this investigation, titanium oxide plates were used as cathode for hydrogen production in the aqueous solutions of sulfuric acid, potassium hydroxide, acetic acid and ammonia hydroxides electrolytes separately. Gaseous hydrogen was produced at the cathode and oxygen at the anode. For this purpose, titanium plates were fabricated in acid solution by anodic oxidation. Microstructure of TiO2 nanorod observation was conducted with scanning electron microscopy (SEM. The effects of operating conditions and the electrochemical test parameters, such as electrolytes concentration, temperature, and cell voltage were investigated. Also the performance of TiO2 cathode was compared to zirconium oxide and graphite electrodes. The results show that the highly rated, hydrogen production performance on TiO2 cathode has better than the other electrodes. The maximum rate of hydrogen production is by TiO2 cathode 8.18 ml/ (h. cm2. The cell efficiency for water electrolysis was reached 95% using titanium oxide electrode in 1.5 M H2SO4.

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

    Science.gov (United States)

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

    2016-06-07

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

  3. Facile Synthesis of Defective TiO2−x Nanocrystals with High Surface Area and Tailoring Bandgap for Visible-light Photocatalysis

    OpenAIRE

    Muhammad Wajid Shah; Yunqing Zhu; Xiaoyun Fan; Jie Zhao; Yingxuan Li; Sumreen Asim; Chuanyi Wang

    2015-01-01

    A facile hydrothermal approach has been developed to prepare defective TiO2−x nanocrystals using Ti(III)-salt as a precursor and L-ascorbic acid as reductant and structure direction agent. The prepared TiO2−x nanocrystals are composed of a highly crystallized TiO2 core and a disordered TiO2−x outer layer, possessing high surface area, controlled oxygen vacancy concentration and tunable bandgap via simply adjusting the amount of added L-ascorbic acid. The defective TiO2−x shows high photocatal...

  4. Ultrafast Flame Annealing of TiO2 Paste for Fabricating Dye-Sensitized and Perovskite Solar Cells with Enhanced Efficiency.

    Science.gov (United States)

    Kim, Jung Kyu; Chai, Sung Uk; Cho, Yoonjun; Cai, Lili; Kim, Sung June; Park, Sangwook; Park, Jong Hyeok; Zheng, Xiaolin

    2017-09-20

    Mesoporous TiO2 nanoparticle (NP) films are broadly used as electrodes in photoelectrochemical cells, dye-sensitized solar cells (DSSCs), and perovskite solar cells (PSCs). State-of-the-art mesoporous TiO2 NP films for these solar cells are fabricated by annealing TiO2 paste-coated fluorine-doped tin oxide glass in a box furnace at 500 °C for ≈30 min. Here, the use of a nontraditional reactor, i.e., flame, is reported for the high throughput and ultrafast annealing of TiO2 paste (≈1 min). This flame-annealing method, compared to conventional furnace annealing, exhibits three distinct benefits. First, flame removes polymeric binders in the initial TiO2 paste more completely because of its high temperature (≈1000 °C). Second, flame induces strong interconnections between TiO2 nanoparticles without affecting the underlying transparent conducting oxide substrate. Third, the flame-induced carbothermic reduction on the TiO2 surface facilitates charge injection from the dye/perovskite to TiO2 . Consequently, when the flame-annealed mesoporous TiO2 film is used to fabricate DSSCs and PSCs, both exhibit enhanced charge transport and higher power conversion efficiencies than those fabricated using furnace-annealed TiO2 films. Finally, when the ultrafast flame-annealing method is combined with a fast dye-coating method to fabricate DSSC devices, its total fabrication time is reduced from over 3 h to ≈10 min. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Hydrothermal etching fabrication of TiO2@graphene hollow structures: mutually independent exposed {001} and {101} facets nanocrystals and its synergistic photocaltalytic effects.

    Science.gov (United States)

    Liu, Hui; Liu, Shuang; Zhang, Zhiling; Dong, Xiaonan; Liu, Tingting

    2016-09-20

    Highly exposed facets TiO2 attracts enormous attention due to its excellent separation effect of photogenerated electron-hole pairs and induced high performance of photocatalytic activity. Herein, a novel hydrothermal etching reaction was used to synthesize graphene-wrapped TiO2 hollow core-shell structures. Different with the reported co-exposed facets TiO2 single crystal nanoparticles, the present TiO2 core layer is composed by the mutually independent exposed {001} and {101} facets nanocrystals. Combined with the reduced graphene oxide shell layer, this graphene-wrapped TiO2 hollow core-shell structures formed a Z-scheme photocatalytic system, which possess simultaneously the high charge-separation efficiency and strong redox ability. Additionally, the as-prepared samples show a higher absorption property for organic molecules and visible light due to the presence of graphene. All of these unique properties ensure the excellent photocatalytic activity for the graphene-wrapped TiO2 hollow structures in the synergistic photo-oxidation of organic molecules and photo-reduced of Cr(VI) process. The TiO2 core composed with mutually independent exposed {001} and {101} facets nanocrystals is propose to play an important role in the fabrication of this Z-scheme photocatalytic system. Fabrication of Z-scheme photocatalytic system based on this unique exposed facets TiO2 nanocrystals will provides a new insight into the design and fabrication of advanced photocatalytic materials.

  6. Hydrothermal etching fabrication of TiO2@graphene hollow structures: mutually independent exposed {001} and {101} facets nanocrystals and its synergistic photocaltalytic effects

    Science.gov (United States)

    Liu, Hui; Liu, Shuang; Zhang, Zhiling; Dong, Xiaonan; Liu, Tingting

    2016-09-01

    Highly exposed facets TiO2 attracts enormous attention due to its excellent separation effect of photogenerated electron-hole pairs and induced high performance of photocatalytic activity. Herein, a novel hydrothermal etching reaction was used to synthesize graphene-wrapped TiO2 hollow core-shell structures. Different with the reported co-exposed facets TiO2 single crystal nanoparticles, the present TiO2 core layer is composed by the mutually independent exposed {001} and {101} facets nanocrystals. Combined with the reduced graphene oxide shell layer, this graphene-wrapped TiO2 hollow core-shell structures formed a Z-scheme photocatalytic system, which possess simultaneously the high charge-separation efficiency and strong redox ability. Additionally, the as-prepared samples show a higher absorption property for organic molecules and visible light due to the presence of graphene. All of these unique properties ensure the excellent photocatalytic activity for the graphene-wrapped TiO2 hollow structures in the synergistic photo-oxidation of organic molecules and photo-reduced of Cr(VI) process. The TiO2 core composed with mutually independent exposed {001} and {101} facets nanocrystals is propose to play an important role in the fabrication of this Z-scheme photocatalytic system. Fabrication of Z-scheme photocatalytic system based on this unique exposed facets TiO2 nanocrystals will provides a new insight into the design and fabrication of advanced photocatalytic materials.

  7. Evaluation of Photocatalytic Properties of Portland Cement Blended with Titanium Oxynitride (TiO2−xNy Nanoparticles

    Directory of Open Access Journals (Sweden)

    Juan D. Cohen

    2015-07-01

    Full Text Available Photocatalytic activity of Portland cement pastes blended with nanoparticles of titanium oxynitride (TiO2−xNy was studied. Samples with different percentages of TiO2−xNy (0.0%, 0.5%, 1%, 3% and TiO2 (1%, 3% were evaluated in order to study their self-cleaning properties. The presence of nitrogen in the tetragonal structure of TiO2 was evidenced by X-ray diffraction (XRD as a shift of the peaks in the 2θ axis. The samples were prepared with a water/cement ratio of 0.5 and a concentration of Rhodamine B of 0.5 g/L. After 65 h of curing time, the samples were irradiated with UV lamps to evaluate the reduction of the pigment. The color analysis was carried out using a Spectrometer UV/Vis measuring the coordinates CIE (Commission Internationale de l’Eclairage L*, a*, b*, and with special attention to the reddish tones (Rhodamine B color which correspond to a* values greater than zero. Additionally, samples with 0.5%, 1%, 3% of TiO2−xNy and 1%, 3% of TiO2 were evaluated under visible light with the purpose of determining the Rhodamine B abatement to wavelengths greater than 400 nm. The results have shown a similar behavior for both additions under UV light irradiation, with 3% being the addition with the highest photocatalytic efficiency obtained. However, TiO2−xNy showed activity under irradiation with visible light, unlike TiO2, which can only be activated under UV light.

  8. Bacteria Adherence Properties of Nitrogen-Doped TiO2 Coatings by Plasma Surface Alloying Technique

    Institute of Scientific and Technical Information of China (English)

    WANG Hefeng; TANG Bin; LIN Naiming; LI Xiuyan; FAN Ailan; SHU Xuefeng

    2012-01-01

    In order to obtain a high-performance surface on 316L stainless steel (S.S) that can meet the requirements in medical material field environment,nitrogen-doped titanium dioxide (TiO2-xNx) was synthesized by oxidative annealing the resulted TiNx coatings in air.Titanium nitride coatings on 316L S.S were obtained by plasma surface alloying technique.The as-prepared coatings were characterized by X-ray diffraction,glow discharge optical emission spectrometer (GDOES),scanning electron microscopy and X-ray photoelectron spectroscopy,respectively.The bacteria adherence property of the TiO2-xNx coatings on S.S on the oral bacteria Streptococcus Mutans was investigated and compared with that of S.S by fluorescence microscopy.The mechanism of the bacteria adherence was discussed.The results show that the TiO2-xNx coatings are composed of anatase crystalline structure.SEM measurement indicates a rough surface morphology with three-dimensional homogenous protuberances after annealing treatment.Because of the photocatalysis and positive adhesion free energy,the TiO2-xNx coatings inhibit the bacteria adherence.

  9. Efficient visible light-induced degradation of rhodamine B by W(NxS1−x)2 nanoflowers

    Science.gov (United States)

    Liu, Peitao; Zhang, Jingyan; Gao, Daqiang; Ye, Weichun

    2017-01-01

    Here, W(NxS1−x)2 nanoflowers were fabricated by simple sintering process. Photocatalytic activity results indicated our fabricated N-doped WS2 nanoflowers shown outstanding photoactivity of degradating of rhodamine B with visible light. Which is attributed to the high separation efficiency of photoinduced electron–hole pairs, the broadening of the valence band (VB), and the narrowing of energy band gap. Meanwhile, our work provided a novel method to induce surface sulfur vacancies in crystals by introduing impurities atoms for enhancing their photodegradation. PMID:28106096

  10. Highly ordered TiO2 nano-pore arrays fabricated from a novel polymethylmethacrylate/polydimethylsiloxane soft template

    Institute of Scientific and Technical Information of China (English)

    P. Zhong; W. X. Que

    2010-01-01

    A novel soft polymer template containing a double-layer structure, which includes a thin layer of polymethylmethacrylate (PMMA) used as a pattern layer and a thicker layer of polydimethylsiloxane (PDMS) used as a back layer, was fabricated from a replica molding process. Anodic aluminum oxide (AAO) template was used as the replica mold to be replicated to the polymethylmethacrylate layer by a thermal infiltration process under a vacuum condition. Results indicate that PMMA/PDMS soft templates with different sizes could be easily fabricated from the as-prepared AAO replica mold. The PMMA/PDMS soft templates were then employed to imprint a TiO2 gel for achieving TiO2 nano-pore arrays. After the imprinting process, the PDMS layer was firstly peeled off and the PMMA layer was then removed into acetonitrile, which can avoid any demolding problems like damages or distortions. The TiO2 nano-pore arrays with the crystalline of anatase could be obtained at a heat treatment temperature of 450°C.

  11. Fabrication of SnO2-TiO2 core-shell nanopillar-array films for enhanced photocatalytic activity

    Science.gov (United States)

    Cheng, Hsyi-En; Lin, Chun-Yuan; Hsu, Ching-Ming

    2017-02-01

    Immobilized or deposited thin film TiO2 photocatalysts are suffering from a low photocatalytic activity due to either a low photon absorption efficiency or a high carrier recombination rate. Here we demonstrate that the photocatalytic activity of TiO2 can be effectively improved by the SnO2-TiO2 core-shell nanopillar-array structure which combines the benefits of SnO2/TiO2 heterojunction and high reaction surface area. The SnO2-TiO2 core-shell nanopillar-array films were fabricated using atomic layer deposition and dry etching techniques via barrier-free porous anodic alumina templates. The photocatalytic activity of the prepared films was evaluated by methylene blue (MB) bleaching under 352 nm UV light irradiation. The results show that the photocatalytic activity of TiO2 film was 45% improved by introducing a SnO2 film between TiO2 and ITO glass substrate and was 300% improved by using the SnO2-TiO2 core-shell nanopillar-array structure. The 45% improvement by the SnO2 interlayer is attributed to the SnO2/TiO2 heterojunction which separates the photogenerated electron-hole pairs in TiO2 for MB degradation, and the high photocatalytic activity of the SnO2-TiO2 core-shell nanopillar-array films is attributed to the three dimensional SnO2/TiO2 heterojunction which owns both the carrier separation ability and the high photocatalytic reaction surface area.

  12. Preparation of TiO2 Coated on Fabrics and Their Photocatalytic Reactivity

    Institute of Scientific and Technical Information of China (English)

    XU Yang; WEI Qu-fu; WANG Ying-ying; HUANG Feng-lin; ZHU He

    2007-01-01

    Nanoseale titanium dioxide functional films were prepared on the surface of the cotton woven fabric and the polyester knitted fabric at room temperature by Radio Frequency (RF) magnetron sputtering process. The surface microstructure and morphology were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). Photocatalytic property of two treated fabrics was tested in solar and ultraviolet (UV) radiation respectively, and their photocatalytic activity was compared. The results showed that the nanoscale titanium dioxide deposited on the surface of the treated fabrics was at different anastasia phase. The treated fabrics have excellent photocatalytic property, and after 30 launderings, the photocatalytic activity still maintained at a high level. Also, it indicated that the photocatalytic activity of the treated fabrics in UV radiation was higher than in solar radiation, but the effect wasn't very distinct. And at the same experimental magnetron sputtering parameters, the cotton coated with the nanoscale titanium dioxide showed better performance than the polyester fabric coated with the nanoscale titanium dioxide in terms of the photocatalytic property.

  13. Fabrication of doped Titania (TiO2) nano-catalysts in the shape of nanofibers

    DEFF Research Database (Denmark)

    Marani, Debora; Silva, Rafael Hubert; Zhang, Wenjing (Angela)

    -catalysts for the removal of the NOx in exhausts via the NH3 Selective Catalytic Reduction method (SCR). The state-of-art system WO3-V2O5 was incorporated into TiO2 ceramic nanofibers through combination of electrospinning and sol-gel process. Catalytic functionalized nanofibers were characterized using SEM, TEM, EDX, BET......, XRD, to analyze fiber diameter, morphology, composition, specific surface area, crystallization phases of TiO2 functionalized, atomic percentage of elements in fiber respectively. Catalytic activity was also measured....

  14. Polyol thermolysis synthesis of TiO2 nanoparticles and its paste formulation to fabricate photoanode for dye-sensitized solar cells

    Science.gov (United States)

    Pratheep, P.; Vijayakumar, E.; Subramania, A.

    2015-05-01

    Titanium dioxide (TiO2) nanoparticles (NPs) were prepared by a simple polyol thermolysis process using various mole ratios of titanium tetrachloride (TiCl4) and polyvinylpyrrolidone (PVP). The prepared TiO2 NPs were characterized by TG/DTA, XRD, SEM, and BET analysis. The TiO2 NPs obtained using 0.1 M of TiCl4 and 0.02 M of PVP have high surface area with lesser particles size than the same obtained using 0.1 M of TiCl4 with other mole ratios of PVP. The high surface area TiO2 NPs were used to formulate TiO2 paste. The impact of ethyl cellulose, terpineol, and dibutyl phthalate in the formulation of TiO2 paste was optimized with respect to standard TiO2 paste ( Dyesol Ltd.) on the adsorption of dye was studied by UV-Vis spectroscopy. The photovoltaic performance of DSSCs fabricated using the formulated TiO2 paste has achieved 97.83 % of power conversion efficiency (PCE) (η = 4.5 %) with respect to the standard TiO2 paste ( Dyesol Ltd.) and its PCE were found to be 4.6 % (η). This PCE value was nearly closer to that of the same DSSC fabricated using the standard TiO2 paste ( Dyesol Ltd.) and higher than the P25 TiO2 ( Degussa) paste and its achieved PCE were found to be 86.04 %.

  15. In situ spectroelectrochemical behaviour of nanocrystalline TiO2 thin films electrode fabricated by pulsed laser deposition

    Institute of Scientific and Technical Information of China (English)

    傅正文; 孔继烈; 秦启宗; 田中群

    1999-01-01

    Nanocrystalline titanium oxide thin films have been successfully deposited on ITO coated glass by pulsed laser ablation of metallic Ti target in O3/O2 ambient gases. The intercalation of Li ions in the anatase TiO2 film electrode is examined by cyclic vohammetry. The electrochromic behaviour of TiO2 electrode is investigated by in-situ visible transmittance measurement, and two absorption bands at 420 and 650 nm are observed. The absorption falling and rising in color changing with excellent revisibility is relative to the insertion and deintercalation processes of Li ion. These resuits suggest that nanocrystalline titanium oxide films fabricated by pulsed laser deposition exhibit excellent spectroelectrochemical property.

  16. Fabrication and application of TiO2-based superhydrophilic-superhydrophobic patterns on titanium substrates for offset printing.

    Science.gov (United States)

    Nakata, Kazuya; Nishimoto, Shunsuke; Kubo, Atsushi; Tryk, Donald; Ochiai, Tsuyoshi; Murakami, Taketoshi; Fujishima, Akira

    2009-06-02

    A fabrication process for superhydrophilic-superhydrophilic patterns on titanium substrates prepared through a combination of an ink-jet technique and site-selective decomposition of a self-assembled monolayer (SAM) by a TiO(2) photocatalyst under UV irradiation is described. We demonstrate that the prepared titanium substrate is applicable as an offset printing plate with high resolution (133 and 150 lines per inch). Furthermore, the superhydrophilic-superhydrophobic patterns on the substrate can be deposited repeatedly after elimination of the patterns by photocatalytic decomposition of TiO(2) under UV irradiation. A second printed image with the renewed substrate showed no significant difference in image quality compared with the initial image.

  17. Aqueous Rechargeable Alkaline CoxNi2-xS2/TiO2 Battery.

    Science.gov (United States)

    Liu, Jilei; Wang, Jin; Ku, Zhiliang; Wang, Huanhuan; Chen, Shi; Zhang, Lili; Lin, Jianyi; Shen, Ze Xiang

    2016-01-26

    An electrochemical energy storage system with high energy density, stringent safety, and reliability is highly desirable for next-generation energy storage devices. Here an aqueous rechargeable alkaline CoxNi2-xS2 // TiO2 battery system is designed by integrating two reversible electrode processes associated with OH(-) insertion/extraction in the cathode part and Li ion insertion/extraction in the anode part, respectively. The prototype CoxNi2-xS2 // TiO2 battery is able to deliver high energy/power densities of 83.7 Wh/kg at 609 W/kg (based on the total mass of active materials) and good cycling stabilities (capacity retention 75.2% after 1000 charge/discharge cycles). A maximum volumetric energy density of 21 Wh/l (based on the whole packaged cell) has been achieved, which is comparable to that of a thin-film battery and better than that of typical commercial supercapacitors, benefiting from the unique battery and hierarchical electrode design. This hybrid system would enrich the existing aqueous rechargeable LIB chemistry and be a promising battery technology for large-scale energy storage.

  18. In situ synthesis and hydrothermal crystallization of nanoanatase TiO2 -SiO2 coating on aramid fabric (HTiSiAF) for UV protection.

    Science.gov (United States)

    Deng, Hui; Zhang, Hongda

    2015-10-01

    TiO2 -SiO2 thin film was prepared by sol-gel method and coated on the aramid fabric to prepare functional textiles. The aramid fabric was dipped and withdrawn in TiO2 -SiO2 gel and hydrothermal crystallization at 80(°) C, then its UV protection functionality was evaluated. The crystalline phase and the surface morphology of TiO2 -SiO2 thin film were characterized using SEM, XRD, and AFM respectively. SEM showed hydrothermal crystallization led to a homogeneous dispersion of anatase nonocrystal in TiO2 -SiO2 film, and XRD suggested the mean particle size of the formed anatase TiO2 was less than 30 nm. AFM indicated that hydrothermal treatment enhanced the crystallization of TiO2 . UV protection analysis suggested that the hydrothermally treated coated textile had a better screening property in comparison with TiO2 -SiO2 gel and native aramid fabric.

  19. Fabrication of N-doped TiO2 coatings on nanoporous Si nanopillar arrays through biomimetic layer by layer mineralization.

    Science.gov (United States)

    Yan, Yong; Wang, Dong; Schaaf, Peter

    2014-06-14

    Si/N-doped TiO2 core/shell nanopillar arrays with a nanoporous structure are fabricated through a simple protein-mediated TiO2 deposition process. The Si nanopillar arrays are used as templates and alternatively immersed in aqueous solutions of catalytic molecules (protamine, PA) and the titania precursor (titanium(iv) bis(ammonium lactato)dihydroxide, Ti-BALDH) for the layer by layer mineralization of a PA/TiO2 coating. After a subsequent calcination, a N-doped TiO2 layer is formed, and its thickness could be controlled by varying the cycles of deposition. Moreover, the nanoporous structure of the Si nanopillars strongly affects the formation of the TiO2 layer. The obtained Si/TiO2 nanocomposites show significantly improved solar absorption compared with commercially purchased TiO2 nanoparticles.

  20. Facile fabrication of three-dimensional TiO2 structures for highly efficient perovskite solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Segeun; Yoon, Jungjin; Ha, Kyungyeon; Kim, Min-cheol; Kim, Dong Hoe; Kim, Sang Moon; Kang, Seong Min; Park, Sei Jin; Jung, Hyun Suk; Choi, Mansoo

    2016-04-01

    The capability of fabricating three dimensional (3-D) nanostructures with desired morphology is a key to realizing effective light-harvesting strategy in optical applications. In this work, we report a novel 3-D nanopatterning technique that combines ion-assisted aerosol lithography (IAAL) and soft lithography that serves as a facile method to fabricate 3-D nanostructures. Aerosol nanoparticles can be assembled into desired 3-D nanostructures via ion-induced electrostatic focusing and antenna effects from charged nanoparticle structures. Replication of the structures with a polymeric mold allows high throughput fabrication of 3-D nanostructures with various liquid-soluble materials. 3-D flower-patterned polydimethylsiloxane (PDMS) stamp was prepared using the reported technique and utilized for fabricating 3-D nanopatterned mesoporous TiO2 layer, which was employed as the electron transport layer in perovskite solar cells. By incorporating the 3-D nanostructures, absorbed photon-to-current efficiency of >95% at 650 nm wavelength and overall power conversion efficiency of 15.96% were achieved. The enhancement can be attributed to an increase in light harvesting efficiency in a broad wavelength range from 400 to 800 nm and more efficient charge collection from enlarged interfacial area between TiO2 and perovskite layers. This hybrid nanopatterning technique has demonstrated to be an effective method to create textures that increase light harvesting and charge collection with 3-D nanostructures in solar cells.

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

    Science.gov (United States)

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

    2014-06-01

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

  2. Surface characteristics of SiO2-TiO2 strip fabricated by laser direct writing

    Institute of Scientific and Technical Information of China (English)

    Aikui Li; Zemin Wang; Jiajan Liu; Xiaoyan Zeng; Chunxia Wang; Hongda Chen

    2008-01-01

    SiO2-TiO2 sol-gel films axe deposited on SiO2/Si by dip-coating technique.The SiO2-TiO2 strips are fabricated by laser direct writing using an ytterbium fiber laser and followed by chemical etching.Surface structures,morphologies and roughness of the films and strips are characterized.The experimental results demonstrate that the SiO2-TiO2 sol-gel film is loose in structure and a shrinkage concave groove forms if the film is irradiated by laser beam.The surface roughness of both non-irradiated and laser irradiated areas increases with the chemical etching time.But the roughness of laser irradiated area increases more than thalt of non-irradiated area under the same etching time.After being etched for 28 s,the surface roughness value of the laser irradiated area increases from 0.3 nm to 3.1 nm.

  3. TiO2/beads as a photocatalyst for the degradation of X3B azo dye

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The feasibility of photocatalytic degradation of X3B azo dye by TiO2/beads photocatalyst was studied. The effects of parameters such as the amount of TiO2/beads, airflow, as well as the concentrations of H2O2, Fe3+, Mg2+ and Na+ on the photocatalytic degradation of X3B azo dye were also studied. The results showed that 25 mg/dm3 X3B azo dye can be photocatalytically degraded completely by 30 min illumination with a 375W medium pressure mercury lamp. Adding a small amount of H2O2 or Fe3+, the efficiencies of photocatalytic degradation of X3B azo dye were increased rapidly. The mechanisms of the reaction and the role of the additives were also investigated. After 120 hours TiO2/beads showed no significant loss of the photocatalytic activity.

  4. Fabrication of Fe-TiC-Al2O3 composites on the surface of steel using a TiO2-Al-C-Fe combustion reaction induced by gas tungsten arc cladding

    Science.gov (United States)

    Sharifitabar, Mahmood; Khaki, Jalil Vahdati; Sabzevar, Mohsen Haddad

    2016-02-01

    The aim of the present study was to fabricate Fe-TiC-Al2O3 composites on the surface of medium carbon steel. For this purpose, TiO2-3C and 3TiO2-4Al-3C- xFe (0 ≤ x ≤ 4.6 by mole) mixtures were pre-placed on the surface of a medium carbon steel plate. The mixtures and substrate were then melted using a gas tungsten arc cladding process. The results show that the martensite forms in the layer produced by the TiO2-3C mixture. However, ferrite-Fe3C-TiC phases are the main phases in the microstructure of the clad layer produced by the 3TiO2-4Al-3C mixture. The addition of Fe to the TiO2-4Al-3C reactants with the content from 0 to 20wt% increases the volume fraction of particles, and a composite containing approximately 9vol% TiC and Al2O3 particles forms. This composite substantially improves the substrate hardness. The mechanism by which Fe particles enhance the TiC + Al2O3 volume fraction in the composite is determined.

  5. Fabrication of multi-sectional TiO2 nanotube arrays by anodization

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We report a facile method to grow multi-sectional TiO2 nanotube arrays consisting of alternating bamboo-shaped and smooth-walled nanotube sections by anodization.Two key factors are necessary for obtaining these morphologies.First,in order to avoid possible disruptions between the conjoint sections of the nanotube,the distribution of hydrogen ions is suggested not to be fiercely disturbed when switching from the first to the second stage.Second,to avoid the disruption of the nanotube at the joint which results from the disparity in diameters between sections,the direct current voltage is set to be the maximum of the square wave voltage.These newly developed TiO2 nanotube arrays are expected to have potential applications in solar cells,drug release and delivery systems.

  6. Fabrication of TiO2 Crystalline Coatings by Combining Ti-6Al-4V Anodic Oxidation and Heat Treatments

    Directory of Open Access Journals (Sweden)

    María Laura Vera

    2015-01-01

    Full Text Available The bio- and hemocompatibility of titanium alloys are due to the formation of a TiO2 layer. This natural oxide may have fissures which are detrimental to its properties. Anodic oxidation is used to obtain thicker films. By means of this technique, at low voltages oxidation, amorphous and low roughness coatings are obtained, while, above a certain voltage, crystalline and porous coatings are obtained. According to the literature, the crystalline phases of TiO2, anatase, and rutile would present greater biocompatibility than the amorphous phase. On the other hand, for hemocompatible applications, smooth and homogeneous surfaces are required. One way to obtain crystalline and homogeneous coatings is by heat treatments after anodic oxidation. The aim of this study is to evaluate the influence of heat treatments on the thickness, morphology, and crystalline structure of the TiO2 anodic coatings. The characterization was performed by optical and scanning electron microscopy, X-ray diffraction, and X-ray reflectometry. Coatings with different colors of interference were obtained. There were no significant changes in the surface morphology and roughness after heat treatment of 500°C. Heat treated coatings have different proportions of the crystalline phases, depending on the voltage of anodic oxidation and the temperature of the heat treatment.

  7. Fabrication of TiO2 Crystalline Coatings by Combining Ti-6Al-4V Anodic Oxidation and Heat Treatments

    Science.gov (United States)

    Schvezov, Carlos Enrique; Ares, Alicia Esther

    2015-01-01

    The bio- and hemocompatibility of titanium alloys are due to the formation of a TiO2 layer. This natural oxide may have fissures which are detrimental to its properties. Anodic oxidation is used to obtain thicker films. By means of this technique, at low voltages oxidation, amorphous and low roughness coatings are obtained, while, above a certain voltage, crystalline and porous coatings are obtained. According to the literature, the crystalline phases of TiO2, anatase, and rutile would present greater biocompatibility than the amorphous phase. On the other hand, for hemocompatible applications, smooth and homogeneous surfaces are required. One way to obtain crystalline and homogeneous coatings is by heat treatments after anodic oxidation. The aim of this study is to evaluate the influence of heat treatments on the thickness, morphology, and crystalline structure of the TiO2 anodic coatings. The characterization was performed by optical and scanning electron microscopy, X-ray diffraction, and X-ray reflectometry. Coatings with different colors of interference were obtained. There were no significant changes in the surface morphology and roughness after heat treatment of 500°C. Heat treated coatings have different proportions of the crystalline phases, depending on the voltage of anodic oxidation and the temperature of the heat treatment. PMID:25784939

  8. Fabrication of TiO2/PU Superhydrophobic Film by Nanoparticle Assisted Cast Micromolding Process.

    Science.gov (United States)

    Li, Jie; Zheng, Jianyong; Zhang, Jing; Feng, Jie

    2016-06-01

    Lotus-like surfaces have attracted great attentions in recent years for their wide applications in water repellency, anti-fog and self-cleaning. This paper introduced a novel process, nanoparticle assisted cast micromolding, to create polymer film with superhydrophobic surface. Briefly, waterborne polyurethane (WPU) sol and nano TiO2/WPU sol were each cast onto the featured surfaces of the poly(dimethylsiloxane) (PDMS) stamps replicated from fresh lotus leaves. After being dried and peeled off from the stamps, PU and TiO2/WPU replica films were created respectively. To the former, only high hydrophobic property was observed with static water contact angle (WCA) at 142.5 degrees. While to the later, superhydrophobic property was obtained with WCA more than 150 degrees and slide angle less than 3 degrees. Scanning electron microscopy (SEM) imaging showed that the PU replica film only had the micro-papillas and the TiO2/PU replica film not only had micro papillas but also had a large number of nano structures distributed on and between the micro-papillas. Such nano and micro hierarchical structures were very similar with those on the natural lotus leaf surface, thus was the main reason for causing superhydrophobic property. Although an elastic PDMS stamp from lotus leaf was used in herein process, hard molds may also be used in theory. This study supplied an alternative technique for large scale production of polymeric films with superhydrophobic.

  9. Dye-sensitized solid-state solar cells fabricated by screen-printed TiO2 thin film with addition of polystyrene balls

    Institute of Scientific and Technical Information of China (English)

    Jing Han; Jin Mao Chen; Xiao Wen Zhou; Yuan Lin; Jing Bo Zhang; Jian Guang Jia

    2008-01-01

    The screen-printed nanoporous TiO2 thin film was employed to fabricate dye-sensitized solid-state solar cells using CuI as hole-transport materials. The solar cell based on nanoporous TiO2 thin film with large pores formed by the addition of polystyrene balls with diameter of 200 nm to the TiO2 paste exhibits photovoltaic performance enhancement, which is attributed to the good contact of CuI with surface of dye-sensitized thin film due to easy penetration of CuI in the film withlarge pores.

  10. The Equation R[subscript n]x = b over Rhotrices

    Science.gov (United States)

    Aminu, Abdulhadi

    2010-01-01

    In this article, we consider the concept of rhotrices and present one-sided system of the form R[subscript n]x = b, where R[subscript n] is an n-dimensional rhotrix, x the unknown n-dimensional rhotrix vector and b the right-hand-side rhotrix vector.

  11. Fabrication, annealing, and electrocatalytic properties of platinum nanoparticles supported on self-organized TiO2 nanotubes

    Institute of Scientific and Technical Information of China (English)

    LEI Bin; XUE Jianjun; JIN Danping; NI Shougao; SUN Haibo

    2008-01-01

    The platinum nanoparticles supported on self-organized TiO2 nanotubes (Pt-TiO2/Ti) were prepared using electrochemical anodic oxidation followed by cathodic reduction.The structure and chemical nature of the Pt-TiO2/Ti electrocatalyst were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM).Both XRD and SEM results indicate the presence of platinum on nanotubular TiO2.The stability of the Pt deposits was also investigated in 0.5 mol/L H2SO4 solution by cyclic voltammetry.The electrocatalytic activity of the Pt-TiO2/Ti catalyst exhibits enhancement effect during electro-oxidation of methanol when annealed to anatase.Successive cyclic voltammograms of methanol oxidation on the Pt-TiO2/Ti electrocatalyst shows unique electrocatalytic characteristics when compared to methanol oxidation on the bulk Pt catalyst.This is because of further quick oxidation of adsorbed CO by Pt (111) facets of Pt particles on self-organized TiO2 nanotubes when the formation of an electroactive film onto the working catalyst surface occurs.

  12. Fabrication characterization and activity of a solar light driven photocatalyst: cerium doped TiO2 magnetic nanofibers.

    Science.gov (United States)

    Li, Cong-Ju; Wang, Bin; Wang, Jiao-Na

    2012-03-01

    A novel magnetic separable composite photocatalytic nanofiber consisting of TiO2 as the major phase, CeO(2-y) and CoFe2O4 as the dopant phase was prepared by sol-gel method and electrospinning technique, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectrum (UV-vis DRS) and vibrating sample magnetometer (VSM). The photocatalytic activity of the resultant CoFe2O4-TiO2 and CeO(2-y)/CoFe2O4-TiO2 nanofibers was evaluated by photodegradation of methylene blue (MB) in an aqueous solution under xenon lamp (the irradiation spectrum energy distribution is similar to sunlight) irradiation in a photochemical reactor. The results showed that the dopant of Ce could affect the absorbance ability and photo-response range. The sample containing 1.0 wt% CeO(2-y) exhibited the highest degradation with 35% for MB under simulate solar light irradiation. Furthermore, the as-synthesized composite photocatalytic nanofibers could be separated easily by an external magnetic field, thus it might hold potential for application in wastewater treatment.

  13. Facile Synthesis of Defective TiO2-x Nanocrystals with High Surface Area and Tailoring Bandgap for Visible-light Photocatalysis.

    Science.gov (United States)

    Wajid Shah, Muhammad; Zhu, Yunqing; Fan, Xiaoyun; Zhao, Jie; Li, Yingxuan; Asim, Sumreen; Wang, Chuanyi

    2015-10-30

    A facile hydrothermal approach has been developed to prepare defective TiO2-x nanocrystals using Ti(III)-salt as a precursor and L-ascorbic acid as reductant and structure direction agent. The prepared TiO2-x nanocrystals are composed of a highly crystallized TiO2 core and a disordered TiO2-x outer layer, possessing high surface area, controlled oxygen vacancy concentration and tunable bandgap via simply adjusting the amount of added L-ascorbic acid. The defective TiO2-x shows high photocatalytic efficiency in methylene blue and phenol degradation as well as in hydrogen evolution under visible light, underlining the significance of the present strategy for structural and bandgap manipulation in TiO2-based photocatalysis.

  14. Fabrication and characterization of photoelectrode thin films with different morphologies of TiO2 nanoparticles for dye-sensitized solar cells.

    Science.gov (United States)

    Kao, Mu-Jung; Chang, Ho; Kuo, Chin-Guo; Huang, Kuohsiu-David; Chen, Yu-Ling

    2011-08-01

    This study deals with the fabrication of three different morphologies of TiO2 nanoparticles to fabricate two-layer photoelectrode thin film for dye-sensitized solar cells (DSSC). The four different TiO2 morphologies are titania nanotubes (Tnt), TiO2 nanoparticles (H220), TiO2 nanoparticle (SP) and commercial DP-25 nanoparticles (P-25). To prepare the thin films of the photoelectrodes, the first layer is coated by H220 TiO2 nanoparticles, and the second is coated by 3 kinds of materials optimally proportionally mixed - P25, SP and Tnt. The photoelectric conversion efficiency of DSSCs with photoelectrodes fabricated using H220 reached 6.31%. Finally, the TiO2 nanaomaterials with four different morphologies were used to prepare a two layer photoelectrode with the structure of H220/P25-Tnt-SP which was combined with a Pt counter electrode to assemble DSSCs. These DSSCs had photoelectric conversion efficiencies of as high as 7.47%.

  15. Preparation of 13X from Waste Quartz and Photocatalytic Reaction of Methyl Orange on TiO2/ZSM-5, 13X and Y-Zeolite.

    Science.gov (United States)

    Wang, Jia-Jie; Jing, You-Hai; Ouyang, Tong; Chang, Chang-Tang

    2015-08-01

    TiO2 photocatalytic reactions not only remove a variety of organic pollutants via complete mineralization, but also destroy the bacterial cell wall and cell membrane, thus playing an important bactericidal role. However, the post-filtration procedures to separate nanometer-levels of TiO2 and the gradual inactivity of photocatalyst during continuous use are defects that limit its application. In this case, we propose loading TiO2 on zeolite for easy separation and 13X is considered as a promising one. In our study, 13X-zeolite was prepared by a hydrothermal method and the source of Si was extracted from waste quartz sand. For comparison, commercial zeolite with different microporous and mesoporous diameters (ZSM-5 and Y-zeolites) were also used as TiO2 supports. The pore size of the three kinds of zeolites are as follows: Y-zeolite > 13X > ZSM-5. Different TiO2 loading content over ZSM-5, 13X and Y-zeolite were prepared by the sol-gel method. XRD, FTIR, BET, UV-vis, TGA and SEM were used for investigation of material characteristics. In addition, the efficiencies of mineralization and photodegradation were studied in this paper. The effects of the loading ratio of TiO2 over zeolites, initial pH, and concentration on photocatalytic performance are investigated. The relationship between best loading content of TiO2 and pore size of the zeolite was studied. The possible roles of the ZSM-5, 13X-zeolites and Y-zeolites support on the reactions and the possible mechanisms of effects were also explored. The best loading content of TiO2 over ZSM-5, 13X and Y-zeolite was found to be 50 wt%, 12.5 wt% and 7 wt%, respectively. The optimum pH condition is 3 with TiO2 over ZSM-5, 13X-zeolites and Y-zeolites. The results showed that the degradation and mineralization efficiency of 12.5 wt%GT13X (TiO2 over 13X) after 90 min irradiation reached 57.9% and 22.0%, which was better than that of 7 wt%GTYZ (TiO2 over Y-zeolites) while much lower than that of 50 wt%GTZ (TiO2 over ZSM-5

  16. Fabrication N, F, and N/F-Doped TiO2 Photoelectrodes for Dye-Sensitized Solar Cells.

    Science.gov (United States)

    Park, Su Kyung; Yun, Tae Kwan; Bae, Jae Young

    2015-08-01

    In this study, pure TiO2, N-doped TiO2, F-doped TiO2, and N/F-doped TiO2 particles were successfully synthesized through the hydrolysis of TiCl4 in the presence of ammonia water and NH4F, respectively. The introduction of doping materials did not affect the crystalline structure. No absorption peak for pure TiO2 was observed above the wavelength of 400 nm. However, the N-doped TiO2 and N/F-doped TiO2 powders exhibited a new absorption peak in the visible light region between 400 and 530 nm. The Jsc value of DSSCs based on the N/F-doped TiO2 electrode was increased by 10% compared to DSSCs using a pure TiO2 electrode, and the energy conversion efficiency was increased by 12%.

  17. Quantitative evaluation of local pulmonary distribution of TiO2 in rats following single or multiple intratracheal administrations of TiO2 nanoparticles using X-ray fluorescence microscopy.

    Science.gov (United States)

    Zhang, Guihua; Shinohara, Naohide; Kano, Hirokazu; Senoh, Hideki; Suzuki, Masaaki; Sasaki, Takeshi; Fukushima, Shoji; Gamo, Masashi

    2016-10-01

    Uneven pulmonary nanoparticle (NP) distribution has been described when using single-dose intratracheal administration tests. Multiple-dose intratracheal administrations with small quantities of NPs are expected to improve the unevenness of each dose. The differences in local pulmonary NP distribution (called microdistribution) between single- and multiple-dose administrations may cause differential pulmonary responses; however, this has not been evaluated. Here, we quantitatively evaluated the pulmonary microdistribution (per mesh: 100 μm × 100 μm) of TiO2 in lung sections from rats following one, two, three, or four doses of TiO2 NPs at a same total dosage of 10 mg kg(-1) using X-ray fluorescence microscopy. The results indicate that: (i) multiple-dose administrations show lower variations in TiO2 content (ng mesh(-1) ) for sections of each lobe; (ii) TiO2 appears to be deposited more in the right caudal and accessory lobes located downstream of the administration direction of NP suspensions, and less so in the right middle lobes, irrespective of the number of doses; (iii) there are not prominent differences in the pattern of pulmonary TiO2 microdistribution between rats following single and multiple doses of TiO2 NPs. Additionally, the estimation of pulmonary TiO2 deposition for multiple-dose administrations imply that every dose of TiO2 would be randomly deposited only in part of the fixed 30-50% of lung areas. The evidence suggests that multiple-dose administrations do not offer remarkable advantages over single-dose administration on the pulmonary NP microdistribution, although multiple-dose administrations may reduce variations in the TiO2 content for each lung lobe. Copyright © 2016 John Wiley & Sons, Ltd.

  18. Quantification of process variables for carbothermic synthesis of UC1-xNx fuel microspheres

    Science.gov (United States)

    Lindemer, T. B.; Silva, C. M.; Henry, J. J.; McMurray, J. W.; Voit, S. L.; Collins, J. L.; Hunt, R. D.

    2017-01-01

    This report details the continued investigation of process variables involved in converting sol-gel-derived, urania-carbon microspheres to ∼820-μm-dia. UC1-xNx fuel kernels in flow-through, vertical Mo and W crucibles at temperatures up to 2123 K. Experiments included calcining of air-dried UO3-H2O-C microspheres in Ar and H2-containing gases, conversion of the resulting UO2-C kernels to dense UO2:2UC in the same gases and vacuum, and its conversion in N2 to UC1-xNx (x = ∼0.85). The thermodynamics of the relevant reactions were applied extensively to interpret and control the process variables. Producing the precursor UO2:2UC kernel of ∼96% theoretical density was required, but its subsequent conversion to UC1-xNx at 2123 K was not accompanied by sintering and resulted in ∼83-86% of theoretical density. Increasing the UC1-xNx kernel nitride component to ∼0.98 in flowing N2-H2 mixtures to evolve HCN was shown to be quantitatively consistent with present and past experiments and the only useful application of H2 in the entire process.

  19. Rutile TiO2 nanowires on anatase TiO2 nanofibers: a branched heterostructured photocatalysts via interface-assisted fabrication approach.

    Science.gov (United States)

    Wang, Changhua; Zhang, Xintong; Shao, Changlu; Zhang, Yanli; Yang, Jikai; Sun, Panpan; Liu, Xueping; Liu, Hong; Liu, Yichun; Xie, Tengfeng; Wang, Dejun

    2011-11-01

    A water-dichloromethane interface-assisted hydrothermal method was employed to grow rutile TiO(2) nanowires (NWs) on electrospun anatase TiO(2) nanofibers (NFs), using highly reactive TiCl(4) as precursor. The water-dichloromethane interface inhibited the formation of rutile NWs in water phase, but promoted the selective radial growth of densely packed rutile NWs on anatase NFs to form a branched heterojunction. The density and length of rutile NWs could be readily controlled by varying reaction parameters. A formation mechanism for the branched heterojunction was proposed which involved (1) the entrapment of rutile precursor nanoparticles at water-dichloromethane interface, (2) the growth of rutile NWs on anatase NFs via Ostwald ripening through the scavengering of interface-entrapped rutile nanoparticles. The heterojunction formed at anatase NF and rutile NW enhanced the charge separation of both under ultraviolet excitation, as evidenced by photoluminescence and surface photovoltage spectra. The branched TiO(2) heterostructures showed higher photocatalytic activity in degradation of rodamine B dye solution than anatase NFs, and the mixture of anatase NFs, and P25 powders, which was discussed in terms of the synergistic effect of enhanced charge separation by anatase-rutile heterojunction, high activity of rutile NWs, and increased specific area of branched heterostructures.

  20. Interrogation of EGFR Targeted Uptake of TiO2 Nanoconjugates by X-ray Fluorescence Microscopy

    Science.gov (United States)

    Yuan, Ye; Paunesku, Tatjana; Arora, Hans; Ward, Jesse; Vogt, Stefan; Woloschak, Gayle

    2013-01-01

    We are developing TiO2 nanoconjugates that can be used as therapeutic and diagnostic agents. Nanoscale TiO2 can be surface conjugated with various molecules and has the unique ability to induce the production of reactive oxygen species after radiation activation. One way to improve the potential clinical usefulness of TiO2 nanoparticles is to control their delivery to malignant cells by targeting them to cancer cell specific antigens. Epidermal Growth Factor Receptor is one potential target that is enriched in epithelial cancers and is rapidly internalized after ligand binding. Hence, we have synthesized TiO2 nanoparticles and functionalized them with a short EGFR binding peptide to create EGFR-targeted NCs. X-ray Fluorescence Microscopy was used to image nanoconjugates within EGFR positive HeLa cells. Further labeling of fixed cells with antibodies against EGFR and Protein A nanogold showed that TiO2 nanoconjugates can colocalize with receptors at the cell’s plasma membrane. Interestingly, with increased incubation times, EGFR targeted nanoconjugates could also be found colocalized with EGFR within the cell nucleus. This suggests that EGFR-targeted nanoconjugates can bind the receptor at the cell membrane, which leads to the internalization of NC-receptor complexes and the subsequent transport of nanoconjugates into the nucleus. PMID:25284907

  1. Facile fabrication of transparent TiO2-C@TiO2-C free-standing film for visible-light photocatalytic application

    Science.gov (United States)

    Hu, Luyang; Zhang, Yumin; Zhang, Shanmei; Li, Benxia

    2017-02-01

    A transparent TiO2-C@TiO2-C free-standing film has been synthesized by two-step hydrothermal method and subsequent thermal annealing. The chemical composition and morphological features of the TiO2-C@TiO2-C film are characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and N2 adsorption-desorption measurement. The results indicate that the flower-like micro/nanostructure TiO2-C particle layers are intimately inhered to porous TiO2-C fibers. The fibers in film are interconnected each other to form a three-dimensional reticulate microstructure, and exhibit intense visible light absorption and high adsorptivity of dye molecules. The interaction between TiO2 and its surface carbon layer in TiO2-C particle promotes the generation of Ti-O-C bonds, which leads to effective charge transfer. Under visible-light irradiation, TiO2-C@TiO2-C film presents enhanced photocatalytic activity for degradation of methylene blue. This work may provide a new viewpoint for designing transparent photocatalytic film for promising applications in heterogeneous photocatalysis.

  2. Solution Combustion Synthesis of TiO2 and Its Use for Fabrication of Photoelectrode for Dye-sensitized Solar Cell

    Institute of Scientific and Technical Information of China (English)

    Shyan-Lung Chung; Ching-Mei Wang

    2012-01-01

    Three different types of TiO2 nano powders were synthesized by a solution combustion synthesis (SCS) method using three different fuels and for comparison, another type of Ti2 nano powder was synthesized by calcination of titanyl hydroxide. These TiO2 nano powders were used to fabricate photoelectrodes for the dye-sensitized solar cell (DSSC) and their performance was compared to that of the DSSC fabricated with Degussa P25 TiO2. The results showed that the SCS TiO2 could work well as photoelectrode for DSSC. The SCS TiO2 contained impurities of C and/or S, thus exhibiting visible light absorption and reduced band gap. The open circuit voltage and the fill factor both varied little among the various TiO2 and thus both had little effect on the photoelectrical conversion efficiency (η). However, the variation of r/was seen to be in quite a good agreement with that of the short circuit current (Isc), suggesting that r/was dominated by Isc. lsc was found to be enhanced by light scattering effect due to the presence of large particles but reduced by high impurity content due to an increase in electron transfer resistance. In addition, the specific surface area of the powders was found to be an important factor affecting the Isc and thus the η.

  3. A Novel Way to Fabricate Superhydrophilic and Antibacterial TiO2 Nanofilms on Glass by Ion Implantation and Subsequent Annealing

    Science.gov (United States)

    Cai, Guangxu; Ren, Feng; Liu, Yichao; Wu, Wei; Fu, Dejun; Xiao, Xiangheng; Jiang, Changzhong

    2013-10-01

    We report a simple and novel method to fabricate high quality titanium dioxide (TiO2) nanofilms on soda lime glass by a solid phase growth process of Ti implantation and subsequent annealling at 500 °C in oxygen atmosphere. The formation of the TiO2 nanofilms is resulted from the slow out-diffusion of implanted Ti ions from the substrates and being oxidized at the surfaces. The formed TiO2 nanofilms show superhydrophilicity and good antibacterial property with good adhesion to substrate and stability, suggesting that the TiO2 nanofilms formed by this method have great potential applications such as antibacterial, anti-fog and self-cleaning transparent glass.

  4. Sonophotocatalytic degradation of dye C.I. Acid Orange 7 by TiO2 and Ag nanoparticles immobilized on corona pretreated polypropylene non-woven fabric.

    Science.gov (United States)

    Marković, Darka; Šaponjić, Zoran; Radoičić, Marija; Radetić, Tamara; Vodnik, Vesna; Potkonjak, Branislav; Radetić, Maja

    2015-05-01

    This study discusses the possibility of using corona pre-treated polypropylene (PP) non-woven fabric as a support for immobilization of colloidal TiO2 and Ag nanoparticles in order to remove dye C.I. Acid Orange 7 from aqueous solution. Dye removal efficiency by sonocatalysis, photocatalysis and sonophotocatalysis was evaluated on corona pre-treated fabric loaded with TiO2 nanoparticles, corona pre-treated fabric double loaded with TiO2 nanoparticles and corona pre-treated fabrics loaded with TiO2 nanoparticles before and after deposition of Ag nanoparticles. In addition, the stability of PP non-woven fabric during these processes was investigated. The substrates were characterized by SEM, EDX and AAS analyses. The change of the dye concentration was evaluated by UV-VIS spectrophotometry. Unlike sonocatalysis and photocatalysis, complete dye removal from both solution and non-woven fabric was obtained already after 240-270 min of sonophotocatalysis. Corona pre-treated PP non-woven fabric loaded with Ag nanoparticles prior to deposition of TiO2 nanoparticles provided excellent degradation efficiency and superior reusability. Sonophotocatalytic degradation of dye in the presence of all investigated samples was the most prominent in acidic conditions. Although this nanocomposite system ensured fast discoloration of dye solution, TOC values of water measured after sonophotocatalysis were not satisfactory because of PP degradation. Therefore, it is suggested to include TOC evaluation in each case study where different supports for TiO2 nanoparticles are used since these nanoparticles may guarantee the dye removal from solution but the stability of support could be problematic causing even more serious environmental impact.

  5. Fabrication and enhanced visible light photocatalytic activity of fluorine doped TiO2 by loaded with Ag.

    Science.gov (United States)

    Lin, Xiaoxia; Rong, Fei; Ji, Xiang; Fu, Degang; Yuan, Chunwei

    2011-11-01

    F-doped TiO2 loaded with Ag (Ag/F-TiO2) was prepared by sol-gel process combined with photoreduction method. The physical and chemical properties of the prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), high-resolution transmission electron microscope (HRTEM), UV-Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL). XPS analysis indicated Ag species existed as Ag0 in the structure of Ag/F-TiO2 samples. UV-Vis diffuse reflectance spectra showed that the light absorption of Ag/F-TiO2 in the visible region had a significant enhancement compared with the F-doped TiO2 (F-TiO2). PL analysis indicated that the electron-hole recombination rate had been effectively inhibited when Ag loaded on the surface of F-TiO2. The photocatalytic activities of the samples were evaluated for the degradation of X-3B (Reactive Brilliant Red dye, C.I. reactive red 2) under visible light (lambda > 420 nm) irradiation. Compared with F-TiO2, the sample of 0.50 Ag/F-TiO2 showed the highest photocatalytic activity. The interaction between F species and metallic Ag was responsible for improving the visible light photocatalytic activity.

  6. Fabrication of Porous TiO2 Hollow Spheres and Their Application in Gas Sensing

    Directory of Open Access Journals (Sweden)

    Hu Peng

    2010-01-01

    Full Text Available Abstract In this work, porous TiO2 hollow spheres with an average diameter of 100 nm and shell thickness of 20 nm were synthesized by a facile hydrothermal method with NH4HCO3 as the structure-directing agent, and the formation mechanism for this porous hollow structure was proved to be the Ostwald ripening process by tracking the morphology of the products at different reaction stages. The product was characterized by SEM, TEM, XRD and BET analyses, and the results show that the as-synthesized products are anatase phase with a high surface area up to 132.5 m2/g. Gas-sensing investigation reveals that the product possesses sensitive response to methanal gas at 200°C due to its high surface area.

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

    Science.gov (United States)

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

    2016-05-01

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

  8. A Macroporous TiO2 Oxygen Sensor Fabricated Using Anodic Aluminium Oxide as an Etching Mask

    Directory of Open Access Journals (Sweden)

    Sheng-Po Wu

    2010-01-01

    Full Text Available An innovative fabrication method to produce a macroporous Si surface by employing an anodic aluminium oxide (AAO nanopore array layer as an etching template is presented. Combining AAO with a reactive ion etching (RIE processes, a homogeneous and macroporous silicon surface can be effectively configured by modulating AAO process parameters and alumina film thickness, thus hopefully replacing conventional photolithography and electrochemical etch methods. The hybrid process integration is considered fully CMOS compatible thanks to the low-temperature AAO and CMOS processes. The gas-sensing characteristics of 50 nm TiO2 nanofilms deposited on the macroporous surface are compared with those of conventional plain (or non-porous nanofilms to verify reduced response noise and improved sensitivity as a result of their macroporosity. Our experimental results reveal that macroporous geometry of the TiO2 chemoresistive gas sensor demonstrates 2-fold higher (~33% improved sensitivity than a non-porous sensor at different levels of oxygen exposure. In addition, the macroporous device exhibits excellent discrimination capability and significantly lessened response noise at 500 °C. Experimental results indicate that the hybrid process of such miniature and macroporous devices are compatible as well as applicable to integrated next generation bio-chemical sensors.

  9. A macroporous TiO2 oxygen sensor fabricated using anodic aluminium oxide as an etching mask.

    Science.gov (United States)

    Lu, Chih-Cheng; Huang, Yong-Sheng; Huang, Jun-Wei; Chang, Chien-Kuo; Wu, Sheng-Po

    2010-01-01

    An innovative fabrication method to produce a macroporous Si surface by employing an anodic aluminium oxide (AAO) nanopore array layer as an etching template is presented. Combining AAO with a reactive ion etching (RIE) processes, a homogeneous and macroporous silicon surface can be effectively configured by modulating AAO process parameters and alumina film thickness, thus hopefully replacing conventional photolithography and electrochemical etch methods. The hybrid process integration is considered fully CMOS compatible thanks to the low-temperature AAO and CMOS processes. The gas-sensing characteristics of 50 nm TiO(2) nanofilms deposited on the macroporous surface are compared with those of conventional plain (or non-porous) nanofilms to verify reduced response noise and improved sensitivity as a result of their macroporosity. Our experimental results reveal that macroporous geometry of the TiO(2) chemoresistive gas sensor demonstrates 2-fold higher (∼33%) improved sensitivity than a non-porous sensor at different levels of oxygen exposure. In addition, the macroporous device exhibits excellent discrimination capability and significantly lessened response noise at 500 °C. Experimental results indicate that the hybrid process of such miniature and macroporous devices are compatible as well as applicable to integrated next generation bio-chemical sensors.

  10. Electronic structures of anatase (TiO2)1-x(TaON)x solid solutions: a first-principles study.

    Science.gov (United States)

    Dang, Wenqiang; Chen, Hungru; Umezawa, Naoto; Zhang, Junying

    2015-07-21

    Sensitizing wide band gap photo-functional materials under visible-light irradiation is an important task for efficient solar energy conversion. Although nitrogen doping into anatase TiO2 has been extensively studied for this purpose, it is hard to increase the nitrogen content in anatase TiO2 because of the aliovalent nitrogen substituted for oxygen, leading to the formation of secondary phases or defects that hamper the migration of photoexcited charge carriers. In this paper, electronic structures of (TiO2)1-x(TaON)x (0 ≤ x ≤ 1) solid solutions, in which the stoichiometry is satisfied with the co-substitution of Ti for Ta along with O for N, are investigated within the anatase crystal structure using first-principles calculations. Our computational results show that the solid solutions have substantially narrower band gaps than TiO2, without introducing any localized energy states in the forbidden gap. In addition, in comparison with the pristine TiO2, the solid solution has a direct band gap when the content of TaON exceeds 0.25, which is advantageous to light absorption. The valence band maximum (VBM) of the solid solutions, which is mainly composed of N 2p states hybridized with O 2p, Ti 3d or Ta 5d orbitals, is higher in energy than that of pristine anatase TiO2 consisting of non-bonding O 2p states. On the other hand, incorporating TaON into TiO2 causes the formation of d-d bonding states through π interactions and substantially lowers the conduction band minimum (CBM) because of the shortened distance between some metal atoms. As a result, the anatase (TiO2)1-x(TaON)x is expected to become a promising visible-light absorber. In addition, some atomic configurations are found to possess exceptionally narrow band gaps.

  11. TiO2 nanowire and TiO2 nanowire doped Ag-PVP nanocomposite for antimicrobial and self-cleaning cotton textile.

    Science.gov (United States)

    Hebeish, A A; Abdelhady, M M; Youssef, A M

    2013-01-16

    The TiO(2) nanowire (TiO(2) Nw) was successfully prepared via hydrothermal method through TiO(2) nanoparticle (TiO(2) Np). TiO(2) Np doped silver and TiO(2) Nw doped silver were prepared via photo-reducing Ag(+) ions to Ag metal on the TiO(2) Np or TiO(2) Nw surfaces. The prepared nanomaterials were evaluated using X-ray (XRD) diffraction pattern, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Bleached untreated cotton fabric and PVP treated cotton fabrics were coated with the synthesized nanomaterials using pad-dry-cure method. Photocatalytic activity of untreated and coated cotton fabrics with TiO(2) nanomaterials was investigated through the fabric self cleaning of MB dye stains. Also, the PVP finished cotton fabric modified by nanomaterials demonstrated antimicrobial activity against Gram positive bacteria, Gram negative bacteria and fungi. The mechanical properties of coated cotton fabric (tear strength, surface roughness, tensile strength and elongation at break) were examined.

  12. Fabrication of TiO2-NTs and TiO2-NTs covered honeycomb lattice and investigation of carrier densities in I-/I3- electrolyte by electrochemical impedance spectroscopy

    Science.gov (United States)

    Baran, Evrim; Yazıcı, Birgül

    2015-12-01

    The TiO2 nanotubes (NTs) were produced by one-step (1S) and two-step (2S) anodization technique. Effects of various anodization potential and times on the growth of TiO2-NTs were investigated by using Field Emission-Scanning Electron Microscopy (FE-SEM). The crystal structure of the electrodes was determined with X-ray powder diffractometry (XRD). The most suitable potential and time for TiO2-NTs obtained by both of anodization methods were found to be 21 V and 4 h. XRD results indicated that 2S anodization technique provided better crystallinity. The electrochemical behaviors of the electrodes in acetonitrile electrolyte contained I-/I3- were examined by utilizing electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) techniques. Electrochemical results showed that 2S anodization technique increases the carrier densities (ND) value of TiO2-NTs, and flat band potential is shifted by 50 mV to more negative values.

  13. Fabrication of α-Fe2O3/TiO2 bi-functional composites with hierarchical and hollow structures and their application in water treatment

    Science.gov (United States)

    Li, Yinhui; Zhang, Na; Chen, Jianxin; Li, Ruijuan; Li, Liang; Li, Kunyu

    2016-02-01

    The α-Fe2O3/TiO2 bi-functional composites with hierarchical and hollow structures are fabricated through a hydrothermal route. The adsorption performance and photocatalytic activity of the composites towards Pb2+ are investigated in this work. Different adsorption kinetics models and equilibrium models are used to explore the adsorption behavior of hierarchical α-Fe2O3/TiO2 hollow spheres. Experimental data show that adsorption kinetics of the hierarchical α-Fe2O3/TiO2 hollow spheres can be fitted well by the pseudo-second-order model, while the isothermal data can be perfectly described by the Langmuir adsorption model. The maximum adsorption capacity of the hierarchical α-Fe2O3/TiO2 hollow spheres is 32.36 mg g-1. Moreover, the hierarchical α-Fe2O3/TiO2 hollow spheres possess photocatalytic oxidation character under simulated solar light irradiation. The results demonstrate that the hierarchical α-Fe2O3/TiO2 hollow spheres, as effective and cheap materials, can be applied to the removal of heavy metal ions from wastewater.

  14. On solutions of $f(x)+f(a_1x)+...+f(a_Nx)=0$ and related equations

    CERN Document Server

    Almira, J M

    2011-01-01

    We study some properties of the solutions of the functional equation $$f(x)+f(a_1x)+...+f(a_Nx)=0,$$ which was introduced in the literature by Mora, Cherruault and Ziadi in 1999, for the case $a_k=k+1$, $k=1,2,...,N$ and studied by Mora in 2008 and Mora and Sepulcre in 2009 and 2011.

  15. 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.

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

    Institute of Scientific and Technical Information of China (English)

    Jingyang Wang; Shaohua Qu; Zhicheng Zhong; Song Wang; Ke Liu; Anzheng Hu

    2014-01-01

    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.

  17. Characterization of photocatalytic TiO2 powder under varied environments using near ambient pressure X-ray photoelectron spectroscopy

    Science.gov (United States)

    Krishnan, Padmaja; Liu, Minghui; Itty, Pierre A.; Liu, Zhi; Rheinheimer, Vanessa; Zhang, Min-Hong; Monteiro, Paulo J. M.; Yu, Liya E.

    2017-01-01

    Consecutive eight study phases under the successive presence and absence of UV irradiation, water vapor, and oxygen were conducted to characterize surface changes in the photocatalytic TiO2 powder using near-ambient-pressure X-ray photoelectron spectroscopy (XPS). Both Ti 2p and O 1s spectra show hysteresis through the experimental course. Under all the study environments, the bridging hydroxyl (OHbr) and terminal hydroxyl (OHt) are identified at 1.1–1.3 eV and 2.1–2.3 eV above lattice oxygen, respectively. This enables novel and complementary approach to characterize reactivity of TiO2 powder. The dynamic behavior of surface-bound water molecules under each study environment is identified, while maintaining a constant distance of 1.3 eV from the position of water vapor. In the dark, the continual supply of both water vapor and oxygen is the key factor retaining the activated state of the TiO2 powder for a time period. Two new surface peaks at 1.7–1.8 and 4.0–4.2 eV above lattice oxygen are designated as peroxides (OOH/H2O2) and H2O2 dissolved in water, respectively. The persistent peroxides on the powder further explain previously observed prolonged oxidation capability of TiO2 powder without light irradiation. PMID:28240300

  18. Characterization of photocatalytic TiO2 powder under varied environments using near ambient pressure X-ray photoelectron spectroscopy

    Science.gov (United States)

    Krishnan, Padmaja; Liu, Minghui; Itty, Pierre A.; Liu, Zhi; Rheinheimer, Vanessa; Zhang, Min-Hong; Monteiro, Paulo J. M.; Yu, Liya E.

    2017-02-01

    Consecutive eight study phases under the successive presence and absence of UV irradiation, water vapor, and oxygen were conducted to characterize surface changes in the photocatalytic TiO2 powder using near-ambient-pressure X-ray photoelectron spectroscopy (XPS). Both Ti 2p and O 1s spectra show hysteresis through the experimental course. Under all the study environments, the bridging hydroxyl (OHbr) and terminal hydroxyl (OHt) are identified at 1.1–1.3 eV and 2.1–2.3 eV above lattice oxygen, respectively. This enables novel and complementary approach to characterize reactivity of TiO2 powder. The dynamic behavior of surface-bound water molecules under each study environment is identified, while maintaining a constant distance of 1.3 eV from the position of water vapor. In the dark, the continual supply of both water vapor and oxygen is the key factor retaining the activated state of the TiO2 powder for a time period. Two new surface peaks at 1.7–1.8 and 4.0–4.2 eV above lattice oxygen are designated as peroxides (OOH/H2O2) and H2O2 dissolved in water, respectively. The persistent peroxides on the powder further explain previously observed prolonged oxidation capability of TiO2 powder without light irradiation.

  19. CO2 dissociation activated through electron attachment on reduced rutile TiO2(110)-1x1 surface

    CERN Document Server

    Tan, Shijing; Zhao, Jin; Wang, Zhuo; Ma, Chuanxu; Zhao, Aidi; Wang, Bing; Luo, Yi; Yang, Jinlong; Hou, Jianguo

    2011-01-01

    Converting CO$_2$ to useful compounds through the solar photocatalytic reduction has been one of the most promising strategies for artificial carbon recycling. The highly relevant photocatalytic substrate for CO$_2$ conversion has been the popular TiO$_2$ surfaces. However, the lack of accurate fundamental parameters that determine the CO$_2$ reduction on TiO$_2$ has limited our ability to control these complicated photocatalysis processes. We have systematically studied the reduction of CO2 at specific sites of the rutile TiO$_2$(110)-1x1 surface using scanning tunneling microscopy at 80 K. The dissociation of CO2 molecules is found to be activated by one electron attachment process and its energy threshold, corresponding to the CO$_2^{\\dot-}$/CO$_2$ redox potential, is unambiguously determined to be 2.3 eV higher than the onset of the TiO$_2$ conduction band. The dissociation rate as a function of electron injection energy is also provided. Such information can be used as practical guidelines for the design...

  20. Band engineered ternary solid solution CdSxSe1-x-sensitized mesoscopic TiO2 solar cells.

    Science.gov (United States)

    Hossain, Md Anower; Jennings, James Robert; Mathews, Nripan; Wang, Qing

    2012-05-21

    The optical band gap of the light absorber and the alignment of its bands with the underlying wide band gap metal oxide are critical for efficient light harvesting and charge separation in semiconductor-sensitized solar cells (SSCs). In practice, these two requirements are however not always fulfilled concomitantly in SSCs. Favourable band alignment in CdSe-sensitized TiO2 requires utilization of quantum sized CdSe, which causes great losses in the harvesting of long wavelength photons due to quantum confinement effects. In the present study, ternary cadmium sulfoselenide (CdSxSe1-x), which has a tunable band gap between those of CdSe and CdS without reducing the dimension, was proposed as a sensitizer for TiO2. CdSxSe1-x was successfully synthesized by alternately depositing CdS and CdSe layers under ambient conditions. SSCs utilizing CdSxSe1-x-sensitized TiO2 yielded a power conversion efficiency of 4.05% under simulated AM1.5 100 mW cm(-2) illumination, rivalling the well-studied cascaded CdS/CdSe electrodes when an aqueous polysulfide solution was used as the electrolyte and Cu2S as the counter electrode. The findings of the present study provide an alternative and viable approach for optimizing the energetics of semiconductor sensitizers for efficient charge separation, while also maintaining good light harvesting.

  1. Application of Turkevich Method for Gold Nanoparticles Synthesis to Fabrication of SiO2@Au and TiO2@Au Core-Shell Nanostructures

    Directory of Open Access Journals (Sweden)

    Paulina Dobrowolska

    2015-05-01

    Full Text Available The Turkevich synthesis method of Au nanoparticles (AuNPs was adopted for direct fabrication of SiO2@Au and TiO2@Au core-shell nanostructures. In this method, chloroauric acid was reduced with trisodium citrate in the presence of amine-functionalized silica or titania submicroparticles. Core-shells obtained in this way were compared to structures fabricated by mixing of Turkevich AuNPs with amine-functionalized silica or titania submicroparticles. It was found that by modification of reaction conditions of the first method, such as temperature and concentration of reagents, control over gold coverage on silicon dioxide particles has been achieved. Described method under certain conditions allows fabrication of semicontinuous gold films on the surface of silicon dioxide particles. To the best of our knowledge, this is the first report describing use of Turkevich method to direct fabrication of TiO2@Au core-shell nanostructures.

  2. Effect of TiO2 blocking layer on TiO2 nanorod arrays based dye sensitized solar cells

    Science.gov (United States)

    Sivakumar, R.; Paulraj, M.

    2016-05-01

    Highly ordered rutile titanium dioxide nanorod (TNR) arrays (1.2 to 6.2 μm thickness) were grown on TiO2 blocking layer chemically deposited on fluorine doped tin oxide (FTO) substrate and were used as photo-electrodes to fabricate dye sensitized solar cells (DSSC's). Homogeneous layer of TiO2 on FTO was achieved by using aqueous peroxo- titanium complex (PTC) solutions via chemical bath deposition. Structural and morphological properties of the prepared samples were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) measurements. TNR arrays (6.2 μm) with TiO2 blocking layer showed higher energy conversion efficiency (1.46%) than that without TiO2 blocking layer. The reason can be ascertained to the suppression of electron-hole recombination at the semiconductor/electrolyte interface by the effect of TiO2 blocking layer.

  3. Fabrication and properties of TiO2 nanofilms on different substrates by a novel and universal method of Ti-ion implantation and subsequent annealing.

    Science.gov (United States)

    Ren, Feng; Zhou, Xiao-Dong; Liu, Yi-Chao; Wang, Yong-Qiang; Cai, Guang-Xu; Xiao, Xiang-Heng; Dai, Zhi-Gao; Li, Wen-Qing; Yan, Shao-Jian; Wu, Wei; Zhang, Chao; Ni, Hong-Wei; Jiang, Chang-Zhong

    2013-06-28

    We report a new, novel and universal method to fabricate high-quality titanium dioxide (TiO2) nanofilms on different substrates by a solid phase growth process of ion implantation and subsequent annealing in oxygen atmosphere. Ti ions were implanted into fused silica, soda lime glass, Z-cut quartz, or (0001) α-sapphire by a metal vapor vacuum arc (MEVVA) ion source implanter to fluences of 0.75, 1.5 and 3 × 10(17) ions cm(-2) with a nominal accelerating voltage of 20 kV. To understand the influence of the annealing temperature, time, and substrate on the formation and phase transformation of the TiO2 nanofilms, the Ti-ion-implanted substrates were annealed in oxygen atmosphere from 500 to 1000 °C for 1-6 h. The formation of TiO2 nanofilms resulted from the slow out-diffusion of implanted Ti ions from the substrates which were then oxidized at the surfaces. The thickness and phase of the nanofilms can be tailored by controlling the implantation and annealing parameters. Since the TiO2 nanofilms are formed under high temperature and low growth rate, they show good crystallinity and antibacterial properties, with good film adhesion and stability, suggesting that the TiO2 nanofilms formed by this method have great potential in applications such as antibacterial and self-cleaning transparent glass.

  4. Fabrication and properties of TiO2 nanofilms on different substrates by a novel and universal method of Ti-ion implantation and subsequent annealing

    Science.gov (United States)

    Ren, Feng; Zhou, Xiao-Dong; Liu, Yi-Chao; Wang, Yong-Qiang; Cai, Guang-Xu; Xiao, Xiang-Heng; Dai, Zhi-Gao; Li, Wen-Qing; Yan, Shao-Jian; Wu, Wei; Zhang, Chao; Ni, Hong-Wei; Jiang, Chang-Zhong

    2013-06-01

    We report a new, novel and universal method to fabricate high-quality titanium dioxide (TiO2) nanofilms on different substrates by a solid phase growth process of ion implantation and subsequent annealing in oxygen atmosphere. Ti ions were implanted into fused silica, soda lime glass, Z-cut quartz, or (0001) α-sapphire by a metal vapor vacuum arc (MEVVA) ion source implanter to fluences of 0.75, 1.5 and 3 × 1017 ions cm-2 with a nominal accelerating voltage of 20 kV. To understand the influence of the annealing temperature, time, and substrate on the formation and phase transformation of the TiO2 nanofilms, the Ti-ion-implanted substrates were annealed in oxygen atmosphere from 500 to 1000 ° C for 1-6 h. The formation of TiO2 nanofilms resulted from the slow out-diffusion of implanted Ti ions from the substrates which were then oxidized at the surfaces. The thickness and phase of the nanofilms can be tailored by controlling the implantation and annealing parameters. Since the TiO2 nanofilms are formed under high temperature and low growth rate, they show good crystallinity and antibacterial properties, with good film adhesion and stability, suggesting that the TiO2 nanofilms formed by this method have great potential in applications such as antibacterial and self-cleaning transparent glass.

  5. TiO_2的基本性质对SCR脱硝催化剂制造的影响%Effect of TiO_2 properties of the manufacture of SCR deNO_x catalyst

    Institute of Scientific and Technical Information of China (English)

    李云涛; 杜云贵; 黄锐

    2012-01-01

    针对广泛应用的蜂窝型SCR催化剂的制造过程,分析了主要原材料TiO2的基本性质,如颗粒大小、粒度分布、形状、团聚程度、化学组成和纯度等,以及这些基本性质对催化剂制造过程中混合、挤出、干燥和煅烧等工序的影响。研究结果表明,精细程度非常高的脱硝催化剂制造过程对TiO2的要求是:粒度分布范围较窄或单一,颗粒为球形或等轴形状,在混合工序所要求的pH值条件下团聚程度低以及TiO2的化学组成和纯度指标高。%Aiming at the fabrication process of widely used honeycomb SCR catalyst,the properties of TiO2 has been analyzed,including particle size,size distribution,shape,degree of agglomeration,chemical composition and purity,and their influence on manufacture procedure of mixing,extrusion,drying and calcinations.The fine fabrication of SCR catalyst is facilitated by the narrow or monodisperse size distribution of TiO2,spherical or equiaxial shape TiO2 particles,low agglomeration degree of TiO2 particles at the required pH in mixing procedure.High standard is also required on the chemical composition and purity of TiO2.

  6. Integrated TiO2 resonators for visible photonics

    CERN Document Server

    Choy, Jennifer T; Deotare, Parag B; Burgess, Ian B; Evans, Christopher C; Mazur, Eric; Loncar, Marko

    2011-01-01

    We demonstrate waveguide-coupled titanium dioxide (TiO2) racetrack resonators with loaded quality factors of 2x10^4 for the visible wavelengths. The structures were fabricated in sputtered TiO2 thin films on oxidized silicon substrates using standard top-down nanofabrication techniques, and passively probed in transmission measurements using a tunable red laser. Devices based on this material could serve as integrated optical elements as well as passive platforms for coupling to visible quantum emitters.

  7. Photocatalytic Properties of Columnar Nanostructured TiO2 Films Fabricated by Sputtering Ti and Subsequent Annealing

    Directory of Open Access Journals (Sweden)

    Zhengcao Li

    2012-01-01

    Full Text Available Columnar nanostructured TiO2 films were prepared by sputtering Ti target in pure argon with glancing angle deposition (GLAD and subsequent annealing at 400°C for different hours in air. Compared with sputtering TiO2 target directly, sputtering Ti target can be carried out under much lower base pressure, which contributes to obtaining discrete columnar nanostructures. In the present study, TiO2 films obtained by annealing Ti films for different hours all kept discrete columnar structures as the Ti films deposited in GLAD regime. The longer the annealing time was, the better the phase transition accomplished from Ti to TiO2 (a mixture of rutile and anatase, and the better it crystallized. In addition, those TiO2 films performed photocatalytic decolorization effectively and showed a law changing over annealing time under UV light irradiation towards methyl orange, which demonstrated the potential applications for treatment of effluent.

  8. Synergetic effects of lanthanum, nitrogen and phosphorus tri-doping on visible- light photoactivity of TiO2 fabricated by microwave-hydrothermal process

    Institute of Scientific and Technical Information of China (English)

    姜洪泉; 刘彦铎; 李井申; 王海燕

    2016-01-01

    Effects of La, N, and P doping on the structural, electronic and optical properties of TiO2 synthesized from TiCl4 hydroly-sis via a microwave-hydrothermal process were investigated by X-ray diffraction, transmission electron microscopy, N2 adsorp-tion-desorption isotherm, X-ray photoelectron spectroscopy, electron paramagnetic resonance, UV-vis absorbance spectroscopy, photoelectrochemical measurements, and photoluminescence spectroscopy. The results showed that the presence of La in the tri-doped TiO2 played a predominant role in inhibiting the recombination of the photogenerated electrons and holes. The existence of the substitutional N, interstitial N, and oxygen vacancies in TiO2 lattices led to the band gap narrowing. It was P-doping rather than La or N doping that played a key role in inhibiting both anatase-to-rutile phase transformation and crystal growth, in stabilizing the mesoporous textural properties, and in increasing the content of surface bridging hydroxyl. Moreover, the tri-doping significantly en-hanced the surface Ti4+−O2−−Ti4+−O−• species.All above-mentioned factors cooperated to result in the enhanced photoactivity of the tri-doped TiO2. As a result, it exhibited the highest photoactivity towards the degradation of 4-chlorophenol (4-CP) under visible-light irradiation among all samples, whichwas much superior to commercial P25 TiO2.

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

    Science.gov (United States)

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

    2012-12-01

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

  10. Inverted organic solar cells based on Cd-doped TiO2 as an electron extraction layer

    Science.gov (United States)

    Ranjitha, A.; Muthukumarasamy, N.; Thambidurai, M.; Velauthapillai, Dhayalan; Madhan Kumar, A.; Gasem, Zuhair M.

    2014-10-01

    Nanocrystalline Cd-doped TiO2 thin films have been prepared by sol-gel method. X-ray diffraction analysis reveals that TiO2 and Cd-doped TiO2 nanocrystalline thin films are of anatase phase. The average grain size of TiO2 and Cd-doped TiO2 nanocrystalline thin films was found to lie in the range of 15-18 nm. Solar cells have been fabricated with a device structure of ITO/Cd-doped TiO2/P3HT:PC71BM/MoO3/Al configuration. The power conversion efficiency of the inverted organic solar cell with Cd-doped TiO2 is 3.06% and is higher than that of TiO2 based organic solar cell (2.64%).

  11. Low-temperature fabrication of brown TiO2 with enhanced photocatalytic activities under visible light

    CERN Document Server

    Wang, Mingzheng; Nie, Biao; Cheng, Hua; Lu, Jian; Luo, Linbao; Xu, Zhengtao; Li, Yang Yang

    2013-01-01

    Titanium dioxide is a photocatalytic substance of great practical importance. However, with its bandgap in the ultraviolet (UV) regime, native forms (undoped) of TiO2 generally exhibits poor photocatalytic activities under visible light. Here we report a facile one-step low-temperature method to treat native TiO2 with NaH in a solution-based protocol. The NaH treatment effectively induces the Ti(III) species and oxygen vacancies into the TiO2 host lattice, and enables the bandgap of TiO2 to be conveniently adjusted from the UV region to the red end of the visible spectrum. The modified TiO2 exhibited significantly enhanced photocatalytic capability under visible light, and lead to faster photo-degradation of organic chemical material. Compared with other ways to reduce the bandgap of TiO2, the approach reported here provides unique advantages for safe, large-scale and economic production of narrow-bandgap TiO2 materials.

  12. Transmission Electron Microscopy and Scanning Transmission X-Ray Microscopy Studies on the Bioaccumulation and Tissue Level Absorption of TiO2 Nanoparticles in Daphnia magna.

    Science.gov (United States)

    Kwon, Dongwook; Nho, Hyun Woo; Yoon, Tae Hyun

    2015-06-01

    In this study, bioaccumulation and tissue-level absorption of TiO2 nanoparticles (NPs) in freshwater invertebrates were investigated using transmission electron microscopy (TEM) and scanning transmission X-ray microscopy (STXM). The TiO2 NPs were used to test impacts of core sizes (i.e., 5 ± 2 nm and 23 ± 7 nm for TiO2(SYN) and TiO2(P25), respectively) and agglomerations (i.e., well dispersed vs. highly agglomerated) on the uptake of TiO2 NPs in Daphnia magna (D. magna). Highly agglomerated TiO2 NPs, regardless of their core sizes, were heavily taken up into the digestive tract of D. magna and no detectable penetration of both TiO2 NPs into the gut epithelial cells of D. magna was observed in TEM and STXM images. However, significant damages involving morphological changes in the microvilli and gut epithelial cells (e.g., irregular shaped microvilli, epithelial cell protrusion, and dilatation of cytoplasmic inclusion) were observed only with the commercial TiO2 NPs (TiO2(P25)) with larger core size and mixed crystalline phase, while the laboratory synthesized TiO2 NPs (TiO2(Syn)) with smaller core size and single crystalline phase showed slight morphological changes in the gut microvilli and epithelial cells. In the case of D. magna exposed to the well dispersed synthetic TiO2 NP ((Cit)TiO2(Syn)), only a negligible amount of TiO2 NPs were found within the digestive tract of the D. magna without any significant damages in the gut microvilli and epithelial cells and any detectable penetrations of TiO2 NPs into epithelial cells of D. magna gut. These TEM and STXM observations confirmed us that uptake of NP into D. magna are strongly dependent on their agglomeration (i.e., hydrodynamic sizes), rather than their core sizes, while direct penetration of NPs into tissues of digestive tract seems unlikely without significant morphological changes (e.g., collapse of the epithelial tissue) caused by high toxicity of NPs or released metal ions.

  13. Fabrication of pure and Ag-doped TiO2 nanorods and study of the lattice strain and the activation energy of the crystalline phases

    Science.gov (United States)

    Riazian, Mehran; Rad, Shima Daliri; Azinabadi, Reza Ramezani

    2013-02-01

    TiO2 nanorods can be used as dye-sensitized solar cells and as various sensors and photocatalysts. These nanorods are synthesized by using a thermal corrosion process in a NaOH solution at 200 °C with TiO2 powder as a source material. In the present work, the synthesis of TiO2 nanorods in anatase, rutile and Ti8O15 phases and the synthesis of TiO2 nanorods by using the sol-gel method and alkaline corrosion to incorporate silver and silver-oxide dopants are reported. The morphologies and the crystalline structures of the TiO2 nanorods are characterized using field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), tunneling electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The obtained results show an aggregation structure at high calcining temperatures with spherical particles and with Ti-O-Ti, Ti-O and Ag-O bonds. The effects of the chemical composition and the calcining temperature on the surface topography, lattice strain and phase crystallization are studied. The activation energy (E) of nanoparticle formation in a pure state during thermal treatment is calculated.

  14. Direct Observation of NN Pairs Transfer in GaP1-xNx (x = 0.12%)

    Institute of Scientific and Technical Information of China (English)

    LU Yi-Jun; GAO Yu-Lin; ZHENG Jian-Sheng; ZHANG Yong; MASCARENHAS A.; XIN H.P.; TU C.W.

    2005-01-01

    @@ Time-resolved photoluminescence (TRPL) was applied to investigate the transient process in GaP1-xNx (x=0.12%) alloy. The filling, transferring and decay processes among nitrogen pairs are directly observed. The NN4pair, either not present or only a small obscure peak under a proper excitation condition in the steady-state photoluminescence spectrum, is well resolved by TRPL.

  15. Solid-state NMR and EPR analysis of carbon-doped titanium dioxide photocatalysts (TiO(2-)(x)C(x)).

    Science.gov (United States)

    Reyes-Garcia, Enrique A; Sun, Yanping; Reyes-Gil, Karla R; Raftery, Daniel

    2009-04-01

    Carbon-doped TiO(2) have received attention recently because of their potential for environmental photocatalysis and solar hydrogen conversion applications. Three different carbon-doped TiO(2) nanoparticle materials were synthesized via sol-gel and hydrothermal procedures, and analyzed by (13)C solid-state nuclear magnetic resonance (SSNMR) and other methods to characterize the environment of the doping species. UV/vis spectra and powder X-ray diffraction (XRD) patterns showed that the synthesized materials absorbed visible light and their crystal structures corresponded to anatase. (13)C SSNMR analyses of TiO(2-)(x)C(x) displayed signals corresponding to carbonate-type or sp(2)-type carbon species. Variable contact CP-MAS and dipolar dephasing analyses gave evidence for the presence and proximity of H atoms near these carbonate species. Electron paramagnetic resonance (EPR) spectroscopy showed that the thermally oxidized TiO(2-)(x)C(x) displayed a complex mixture of point defects, electron and hole trapping centers, all attributable to the incorporation of carbon, while the XPS data ruled out the presence of carbide species.

  16. On the Diophantine equation (12n)x+(35n)y=(37n)z%关于丢番图方程(12n)x(35n)y=(37n)z

    Institute of Scientific and Technical Information of China (English)

    杨志娟; 翁建欣

    2012-01-01

      Using the properties of congruences and the order of elements, we show that, for any positive integer n, the Diophantine equation (12n)x+(35n)y =(37n)z has no solution other than (x, y, z)=(2, 2, 2) in positive integers.%  运用同余及元素阶的性质,证明对任意正整数n,丢番图方程(12n)x+(35n)y=(37n)z仅有正整数解(x, y, z)=(2,2,2)。

  17. Photonic crystal heterostructures fabricated by TiO2 and ZnO inverse opals using colloidal crystal template with single kind of microspheres

    Science.gov (United States)

    Zhang, Yongna; Fu, Ming; Wang, Jigang; He, Dawei; Wang, Yongsheng

    2012-09-01

    The fabrication of photonic crystal heterostructures is important for the applications in the fields of integrated photonic crystal chips, multi-frequency optical Bragg filters or mirrors. However, multiple steps of self-assembly process of microspheres are always employed in the fabrication of photonic crystal heterostructures, which may produce lattice mismatches of colloidal crystals. Therefore, photonic crystal heterostructures fabricated by using colloidal crystal template with single kind of microspheres were investigated in this paper. A colloidal crystal template with uniform periodicity was firstly formed by monodispersed polystyrene microsphere. Then ZnO was electrodeposited into the interstices of the template. The thickness of ZnO was controlled to be less than the thickness of the template by varying the deposition time. After the TiO2 precursor was filled into the top voids in the template, the polystyrene colloidal crystal template was removed and photonic crystal heterostructures fabricated by ZnO and TiO2 were formed. Both the dielectric constant and the periodicity of the two parts of the heterostructures are different due to the shrinkage of the sol-gel process. The ZnO/TiO2 heterostructures have a broad photonic stop band which is the superposition of photonic stop bands of ZnO inverse opals and TiO2 inverse opals.

  18. Thermo-Optical Properties of Thin-Film TiO2–Al2O3 Bilayers Fabricated by Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Rizwan Ali

    2015-05-01

    Full Text Available We investigate the optical and thermo-optical properties of amorphous TiO\\(_2\\–Al\\(_2\\O\\(_3\\ thin-film bilayers fabricated by atomic layer deposition (ALD. Seven samples of TiO\\(_2\\–Al\\(_2\\O\\(_3\\ bilayers are fabricated by growing Al\\(_2\\O\\(_3\\ films of different thicknesses on the surface of TiO\\(_2\\ films of constant thickness (100 nm. Temperature-induced changes in the optical refractive indices of these thin-film bilayers are measured by a variable angle spectroscopic ellipsometer VASE\\textsuperscript{\\textregistered}. The optical data and the thermo-optic coefficients of the films are retrieved and calculated by applying the Cauchy model and the linear fitting regression algorithm, in order to evaluate the surface porosity model of TiO\\(_2\\ films. The effects of TiO\\(_2\\ surface defects on the films' thermo-optic properties are reduced and modified by depositing ultra-thin ALD-Al\\(_2\\O\\(_3\\ diffusion barrier layers. Increasing the ALD-Al\\(_2\\O\\(_3\\ thickness from 20 nm to 30 nm results in a sign change of the thermo-optic coefficient of the ALD-TiO\\(_2\\. The thermo-optic coefficients of the 100 nm-thick ALD-TiO\\(_2\\ film and 30 nm-thick ALD-Al\\(_2\\O\\(_3\\ film in a bilayer are (0.048 \\(\\pm\\ 0.134 \\(\\times 10 ^{-4} {^\\circ}\\mathrm {C}^{-1}\\ and (0.680 \\(\\pm\\ 0.313 \\(\\times 10^{-4} {^\\circ} \\mathrm {C}^{-1}\\, respectively, at a temperature \\(T = 62 ^\\circ \\mathrm{C}\\.

  19. Fabrication and characterization of a nanostructured TiO2/In2S3-Sb2S3/CuSCN extremely thin absorber (eta) solar cell

    Science.gov (United States)

    Huerta-Flores, Alí M.; García-Gómez, Nora A.; de la Parra-Arciniega, Salomé M.; Sánchez, Eduardo M.

    2016-08-01

    In this work we report the successful assembly and characterization of a TiO2/In2S3-Sb2S3/CuSCN extremely thin absorber solar cell. Nanostructured TiO2 deposited by screen printing on an ITO substrate was used as an n-type electrode. An ∼80 nm extremely thin layer of the system In2S3-Sb2S3 deposited by successive ionic layer adsorption and a reaction (silar) method was used as an absorber. The voids were filled with p-type CuSCN and the entire assembly was completed with a gold contact. The solar cell fabricated with this heterostructure showed an energy conversion efficiency of 4.9%, which is a promising result in the development of low cost and simple fabrication of solar cells.

  20. Fabrication of TiO2/MoS2@zeolite photocatalyst and its photocatalytic activity for degradation of methyl orange under visible light

    Science.gov (United States)

    Zhang, Weiping; Xiao, Xinyan; Zheng, Lili; Wan, Caixia

    2015-12-01

    TiO2/MoS2@zeolite composite photocatalysts with visible-light activity were fabricated via a simple ultrasonic-hydrothermal synthesis method, using TiCl4 as Ti source, MoS2 as a direct sensitizer, glycerol water solution with certain dispersion agent as hydrolytic agent, and zeolite as carrier. The structure, morphology, composition, optical properties, and specific surface area of the as-prepared photocatalysts were characterized by using XRD, FTIR, SEM-EDS, TEM, XPS, UV-vis, PL and BET analyzer, respectively. And the photocatalytic degradation of methyl orange (MO) in aqueous suspension has been employed to evaluate the photocatalytic activity and degradation kinetics of as-prepared photocatalysts with xenon lamp as irradiation source. The results indicate that: (1) TiO2/MoS2@zeolite composite photocatalysts exhibit enhanced photocatalytic activities for methyl orange (MO) degradation compared to Degussa P25; (2) photocatalytic degradation of MO obeys Langmuir-Hinshelwood kinetic model (pseudo-first order reaction), and its degradation rate constant (kapp) (2.304 h-1) is higher than that of Degussa P25 (0.768 h-1); (3) the heterostructure consisted of zeolite, MoS2 and TiO2 nanostructure could provide synergistic effect for degradation of MO due to the efficient electron transfer process and better absorption property of TiO2/MoS2@zeolite composite photocatalyst.

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

    Science.gov (United States)

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

    2016-01-01

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

  2. Review on the Photocatalyst Coatings of TiO2: Fabrication by Mechanical Coating Technique and Its Application

    Directory of Open Access Journals (Sweden)

    Yun Lu

    2015-07-01

    Full Text Available This review presents the latest results of studies directed at photocatalyst coatings of titanium dioxide (TiO2 prepared by mechanical coating technique (MCT and its application. Compared with traditional coating techniques, MCT is a simple, low cost and useful coating formation process, which is proposed and developed based on mechanical frictional wear and impacts between substrate materials and metal powder particles in the bowl of planetary ball mill. The formation process of the metal coatings in MCT includes four stages: The nucleation by adhesion, the formation and coalescence of discrete islands, formation and thickening of continuous coatings, exfoliation of continuous coatings. Further, two-step MCT was developed based on the MCT concept for preparing composite coatings on alumina (Al2O3 balls. This review also discusses the influence on the fabrication of photocatalyst coatings after MCT and improvement of its photocatalytic activity: oxidation conditions, coating materials, melt salt treatment. In this review, the oxidation conditions had been studied on the oxidation temperature of 573 K, 673 K, 773 K, 873 K, 973 K, 1173 K and 1273 K, the oxidation time of 0.5 h, 1 h, 3 h, 10 h, 15 h, 20 h, 30 h, 40 h, and 50 h. The photocatalyst coatings showed the highest photocatalytic activity with the oxidation condition of 1073 K for 15 h. The metal powder of Ti, Ni and Cr had been used as the coating materials. The composite metal powder could affect the surface structure and photocatalytic activity. On the other hand, the melt salt treatment with KNO3 is an effective method to form the nano-size structure and enhance photocatalytic activity, especially under visible light.

  3. Fabrication of Fe-doped TiO2 nanoparticles and investigation of photocatalytic decolorization of reactive red 198 under visible light irradiation.

    Science.gov (United States)

    Moradi, Halimeh; Eshaghi, Akbar; Hosseini, Seyed Rahman; Ghani, Kamal

    2016-09-01

    In this research, Fe-doped TiO2 nanoparticles with various Fe concentrations (0. 0.1, 1, 5 and 10wt%) were prepared by a sol-gel method. Then, nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray analysis (EDX), BET surface area, photoluminescence (PL) spectroscopy and UV-vis diffuse reflectance spectroscopy (DRS). The photocatalytic activity of the nano-particles was evaluated through degradation of reactive red 198 (RR 198) under UV and visible light irradiations. XRD results revealed that all samples contained only anatase phase. DRS showed that the Fe doping in the titania induced a significant red shift of the absorption edge and then the band gap energy decreased from 3 to 2.1eV. Photocatalytic results indicated that TiO2 had a highest photocatalytic decolorization of the RR 198 under UV irradiation whereas photocatalytic decolorization of the RR 198 under visible irradiation increased in the presence of Fe-doped TiO2 nanoparticles. Among the samples, Fe-1wt% doped TiO2 nanoparticles showed the highest photocatalytic decolorization of RR198 under visible light irradiation.

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

    Directory of Open Access Journals (Sweden)

    Zhang X

    2016-01-01

    Full Text Available Xiaochen Zhang,1 Zhiyuan Zhang,1 Gang Shen,2 Jun Zhao2 1Department of Oral and Maxillofacial Surgery, 2Department of Orthodontics, College of Stomatology, Ninth People’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China Abstract: To enhance biocompatibility and osseointegration between titanium implants and surrounding bone tissue, numerous efforts have been made to modify the surface topography and composition of Ti implants. In this paper, Lenti-BMP-2-loaded TiO2 nanotube coatings were fabricated by lyophilization in the presence of trehalose to functionalize the surface. We characterized TiO2 nanotube layers in terms of the following: surface morphology; Lenti-BMP-2 and trehalose release; their ability to induce osteogenesis, proliferation, and anti-inflammation in vitro; and osseointegration in vivo. The anodized TiO2 nanotube surfaces exhibited an amorphous glassy matrix perpendicular to the Ti surface. Both Lenti-BMP-2 and trehalose showed sustained release over the course of 8 days. Results from real-time quantitative polymerase chain reaction studies demonstrated that lyophilized Lenti-BMP-2/TiO2 nanotubes constructed with trehalose (Lyo-Tre-Lenti-BMP-2 significantly promoted osteogenic differentiation of bone marrow stromal cells but not their proliferation. In addition, Lyo-Tre-Lenti-BMP-2 nanotubes effectively inhibited lipopolysaccharide-induced interleukin-1β and tumor necrosis factor-α production. In vivo, the formulation also promoted osseointegration. This study presents a promising new method for surface-modifying biomedical Ti-based implants to simultaneously enhance their osteogenic potential and anti-inflammatory properties, which can better satisfy clinical needs. Keywords: osteogenesis, anti-inflammation, TiO2 nanotube layers, Lenti-BMP-2, lyophilization, trehalose 

  5. Fabrication of High Efficiency Dye-Sensitized Solar Cells Based on TiO2 Nanoparticles Embedded in Ti Substrate.

    Science.gov (United States)

    Kim, Kang-Pil; Lee, Sang-Ju; Hwang, Dae-Kue; Kim, Dae-Hwan; Heo, Young-Woo

    2015-01-01

    We have embedded a TiO2 nanoparticle (NP) photoelectrode in a Ti substrate to improve the cell efficiency of conventional TiO2 NP based dye-sensitized solar cells (DSSCs) using Ti substrate. Compared to the conventional standing-type (TiO2 NPs on Ti substrate) DSSCs, the embedded-type (TiO2 NPs embedded in Ti substrate) DSSCs have shown an approximately 35% improvement in power conversion efficiency due to the improvement of J(sc). The embedded-type DSSCs have more charge transport paths than do standing-type DSSCs due to the increase of contact area between the TiO2 NP sidewall and the Ti substrate. This increased contact area decreases the electrical resistance and increases the charge collection efficiency, which leads to the improvement of J(sc). The embedded-type NP-DSSCs are very effective DSSC structures for enhancing the power conversion efficiency of Ti substrate based DSSCs.

  6. Fabrication and Property Investigation of the Highly Ordered TiO2 Nanotube Arrays%高度有序TiO2纳米管阵列的制备及其光催化性能研究

    Institute of Scientific and Technical Information of China (English)

    兰宇卫; 周立亚; 童张法; 庞起; 冷利民; 韩建鹏; 王凡

    2011-01-01

    室温下在NH4F、乙二醇的混合溶液中采用阳极氧化法在纯Ti片表面得到一层结构高度有序、分布均匀、垂直取向TiO2纳米管阵列,通过调整阳极氧化工艺条件可实现对其结构参数(如管径、管壁厚度、管长等)的有效控制:对TiO2纳米管阵列进行扫描电子显微镜(SEM)、X-射线衍射(XRD)检测;测试了TiO2纳米管降解甲基橙的光催化性能.结果表明:在优化条件下制备得到了高密度排列的TiO2纳米管阵列;在500W高压汞灯照射40min后,初始摩尔浓度为20 mg·L-1的甲基橙在pH=2.0时,降解率达到99.4%,溶液中加入H2O2可以提高TiO2纳米管光降解催化活性.%The highly ordered and uniform TiO2 nanotube arrays were fabricated by anodic oxidation of titanium foil in ethylene glycol solution containing NH4 F. The diameter, density, length and wall thickness of the prepared nanotube arrays can be controlled effectively by varying the anodization parameters. The microstructures and morphologies of the fabricated TiO2 nanotube were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD), and its photocatalytic properties were investigated via the degradation of methyl orange. The results show that the highly ordered and uniform TiO2 nanotube arrays could be grown under the conditions optimized by authors. Using the prepared TiO2 nanotube arrays as photocatalyst and after 40 min illumination of the high voltage mercury lamp (500 W), the degradation ratio of methyl orange in its aqueous solution with concentratin of 20 mg.L-1 can reach 99.4% when the solution pH value is 2.0. And it was found that the photoeatalysis of TiO2 nanotube can be improved by adding H202 into the solution.

  7. Oxygen-Deficient TiO2 - x/Methylene Blue Colloids: Highly Efficient Photoreversible Intelligent Ink.

    Science.gov (United States)

    Imran, M; Yousaf, Ammar B; Zhou, Xiao; Liang, Kuang; Jiang, Yi-Fan; Xu, An-Wu

    2016-09-06

    Oxygen-sensitive photoreversible intelligent ink capable of assessment with the human eye is an ongoing demand in the modern era. In the food industry, redox-dye-based oxygen indicator films have been proposed, but the leaching of dyes from the film that contaminates the food is one unsolved issue. On the other hand, it is also highly desirable to develop rewritable paper that significantly reduces the pressure on modern society for the production and consumption of paper. Herein, we have developed an oxygen-deficient TiO2 - x/methylene blue (MB) sol without relying on external sacrificial electron donors (SEDs) for photoreversible color switching. Oxygen vacancies in TiO2 - x can work as electron donor to favor the adsorption of the substrate and improve the charge separation that is required for the redox-based color-switching system. The problems of rewriteable paper and food packaging are addressed as two sides of a single coin in this article. We have used hydroxyethyl cellulose (HEC) for rewritable paper that can significantly delay the oxidation of leuco-MB (LMB) through hydrogen bonding and retain the printed information for a long time. The dye leaching from oxygen indicator films is also significantly reduced (only 1.54%) by using furcelleran as the coating polymer that is extracted from edible red seaweed.

  8. Characterization and Photocatalytic Efficiency of TiO2/Ti Beads Fabricated by Simple Heat-Treatment

    Institute of Scientific and Technical Information of China (English)

    Altaagerel Amarjargal; Leonard D. Tijing; Mi-Hwa Yu; Chae-Hwa Kim; Chan-Hee park; Dong-Won Kim; Cheol-Sang Kim

    2012-01-01

    The goal of the present study was to investigate the photocatalytic efficiency of titanium dioxide (TiO2) formed on titanium (Ti) bead substrate (referred herein as TiO2/Ti beads) by heat treatment when exposing to ultraviolet (UV) light irradiation. Escherichia coli was used as the model test organism. The results show 4-log and 7-log decrease in bacterial concentration after a test time of 15 and 120 min, respectively, using TiO2/Ti beads irradiated with UV light in a tin-foil covered beaker. This article presents the potential of TiO2 on Ti bead substrate formed by simple heat-treatment together with UV light for bacterial inactivation.

  9. Fabrication of TiO2@Yeast-Carbon Hybrid Composites with the Raspberry-Like Structure and Their Synergistic Adsorption-Photocatalysis Performance

    Directory of Open Access Journals (Sweden)

    Dang Yu

    2013-01-01

    Full Text Available In the present work, we report the preparation and photocatalytic properties of TiO2@yeast-carbon with raspberry-like structure using a pyrolysis method. The products are characterized by field emission scanning electron microscopy (FE-SEM, energy dispersive spectrometry (EDS, X-ray diffraction (XRD, thermal gravimetric and differential thermal analysis (TGA-DTA, Fourier transformed infrared spectroscopy (FT-IR, and ultraviolet visible spectroscopy (UV-VIS, respectively. The results show that the hybrid TiO2@yeast-carbon microspheres have ordered elliptic shapes of uniform size (length = 3.5±0.3 μm; width = 2.5±0.5 μm. UV-VIS ascertains that the as-prepared microspheres possess an obvious light response in a wide range of 250–400 nm. In the decomposition of typical model pollutants including methylene blue and congo red, the hybrid composites exhibited excellent photocatalytic activity for the methylene blue due to the enhanced adsorption ability. Further investigation reveals that the combined effect of adsorption from the yeast-carbon core and photocatalytic degradation from the attached TiO2 nanoparticles were responsible for the improvement of the photocatalytic activities. Hereby, the raspberry-like TiO2@yeast-carbon has promising applications in water purification.

  10. Cold Light Mirror Fabricated by Electron Beam Evaporation of TiO2 and SiO2

    Institute of Scientific and Technical Information of China (English)

    ZHONGDi-sheng; XUGuang-zhong; 等

    2000-01-01

    A process suitable for production on a large scale of cold light mirror for film projector is introduced.Deposition parameters required for producing TiO2/SiO2 optical multialyer systems by electron beam evaporation of TiO2 and SiO2 starting materials are investigated.Manufacture and techniques of cold mirror and the adhesion, stability, wear and corrosion resistance of cold mirror by this process are discussed.The result shows that cold mirror produced has good optical properties and better adhesion.

  11. Formation Mechanistism Study of TiO2 Film Comprising Nanotubes and Nanoparticles

    Science.gov (United States)

    Yang, Di; Wang, Yi-quan; Ren, Guo-bin; Feng, Shuai; Chen, Yuan-yuan; Wang, Wen-zhong

    2012-02-01

    A novel titanium dioxide (TiO2) film comprising both nanotubes and nanopaticles was fabricated by an anodization process of the modified titanium. The local electric field at the anodized surface was simulated and its influence on the morphology of the TiO2 film was discussed. The results show that the electric field strength is enhanced by the covering. The growth rate of TiO2 increases with the assist of the local electric field. However, TiO2 dissolution is hindered since the local electric field prevents [TiF6]6- from diffusing. It means that the balance condition for the formation of nanotubes is broken, and TiO2 nanoparticles are formed. Moreover, the crystal structure of the TiO2 film was confirmed using X-ray diffraction and Raman analysis. The anatase is a main phase for the proposed film.

  12. Data set for fabrication of conformal two-dimensional TiO2 by atomic layer deposition using tetrakis (dimethylamino) titanium (TDMAT) and H2O precursors.

    Science.gov (United States)

    Zhuiykov, Serge; Akbari, Mohammad Karbalaei; Hai, Zhenyin; Xue, Chenyang; Xu, Hongyan; Hyde, Lachlan

    2017-08-01

    The data and complementary information presented hare are related to the research article of "http://dx.doi.org/10.1016/j.matdes.2017.02.016; Materials and Design 120 (2017) 99-108" [1]. The article provides data and information on the case of atomic layer deposition (ALD) of ultra-thin two-dimensional TiO2 film. The chemical structure of precursors, and the fabrication process were illustrated. The data of spectral ellipsometric measurements and the methods of calculations were presented. Data of root mean square roughness and the average roughness of the ADL TiO2 film are presented. The method of bandgap measurements and the bandgap calculation are also explained in the present data article.

  13. Data set for fabrication of conformal two-dimensional TiO2 by atomic layer deposition using tetrakis (dimethylamino titanium (TDMAT and H2O precursors

    Directory of Open Access Journals (Sweden)

    Serge Zhuiykov

    2017-08-01

    Full Text Available The data and complementary information presented hare are related to the research article of “http://dx.doi.org/10.1016/j.matdes.2017.02.016; Materials and Design 120 (2017 99–108” [1]. The article provides data and information on the case of atomic layer deposition (ALD of ultra-thin two-dimensional TiO2 film. The chemical structure of precursors, and the fabrication process were illustrated. The data of spectral ellipsometric measurements and the methods of calculations were presented. Data of root mean square roughness and the average roughness of the ADL TiO2 film are presented. The method of bandgap measurements and the bandgap calculation are also explained in the present data article.

  14. A facile approach for high surface area electrospun TiO2 nanostructures for photovoltaic and photocatalytic applications.

    Science.gov (United States)

    Arun, T A; Madhavan, Asha Anish; Chacko, Daya K; Anjusree, G S; Deepak, T G; Thomas, Sara; Nair, Shantikumar V; Nair, A Sreekumaran

    2014-03-28

    A rice-shaped TiO2-ZnO composite was prepared by electrospinning a mixture comprising the precursors of TiO2 and ZnO in polyvinyl acetate polymer dissolved in N,N-dimethyl acetamide. The electrospun nanofibers upon heat treatment in air resulted in collapse of the continuous fiber morphology and the formation of the rice-shaped TiO2-ZnO composite. The TiO2-ZnO composite was then treated with dilute acetic acid under hydrothermal conditions to etch ZnO from the TiO2-ZnO composite to get coral-shaped anisotropic TiO2. The structural anisotropy of TiO2 produced by the selective etching of ZnO resulted in a high surface area of 148 m(2) g(-1) for the TiO2. The initial and final materials were characterized by scanning electron microscopy, transmission electron microscopy, Raman and XPS spectroscopies, powder X-ray diffraction and BET surface area measurements. The utility of the anisotropic TiO2 in photovoltaics and photocatalysis was explored. Dye-sensitized solar cells fabricated using the TiO2 showed a conversion efficiency of 6.54% as against 4.8% for a control experiment with the rice-shaped TiO2. The anisotropic TiO2 also showed good photocatalysis in the degradation of methyl orange dye and phenol.

  15. Electronic Band Structures of TiO2 with Heavy Nitrogen Doping

    Institute of Scientific and Technical Information of China (English)

    XUE Jinbo; LI Qi; LIANG Wei; SHANG Jianku

    2008-01-01

    The first-principles density-functional calculation was conducted to investigate the electronic band structures of titanium dioxide with heavy nitrogen doping (TiO2-xNx).The calculation results indicate that when x≤0.25,isolated N 2p states appear above the valence-band maximum of TiO2 without a band-gap narrowing between O 2p and Ti 3d states.When x≥0.50,an obvious band gap narrowing between O 2p and Ti 3d states was observed along with the existence of isolated N 2p states above the valence-band of TiO2,indicating that the mechanism proposed by Asahi et al operates under heavy nitrogen doping condition.

  16. Reduction of Hg1 - xCdxTe native oxide during the SiNx deposition process

    Science.gov (United States)

    Sudo, G.; Kajihara, N.; Miyamoto, Y.; Tanikawa, K.

    1987-11-01

    Electron cyclotron resonance plasma chemical vapor deposition enables low-temperature SiNx deposition on Hg1-xCdxTe (MCT). The SiNx film has an excellent interface on MCT with a low surface state density of 1.0×1011 cm-2 eV-1 and a low fixed charge of -1.4×1011 cm-2. A detailed analysis by x-ray photoelectron spectroscopy and Auger electron spectroscopy spectra of Te, Cd, and Si at the SiNx/MCT interface indicated that the SiNx deposition reduces the naturally grown MCT native oxide. The oxygen taken from Te oxidizes SiH4 and produces silicon oxides which remain in the SiNx film. Since a chemical shift caused by oxidized Cd at the fresh surface of MCT is very slight, intentionally oxidized samples were used to confirm the above reaction. The analysis of the shape of the Si(2p) peak at the interface indicated that the silicon oxides are composed of SiO and SiO2. Thermodynamic considerations support such a mechanism.

  17. Fabrication and photoelectrochemical characteristics of In2S3 nano-flower films on TiO2 nanorods arrays

    Science.gov (United States)

    Han, Minmin; Yu, Limin; Chen, Wenyuan; Wang, Wenzhen; Jia, Junhong

    2016-04-01

    The In2S3 nano-flower films on TiO2/FTO (Fluorine-doped tin oxide) substrates were synthesized via hydrothermal method and the photoelectrochemical performances of In2S3/TiO2 photoelectrodes were characterized. The roles of PSS (poly(sodium-p-styrenesul-fonate)) and PEG (polyethylene glycol) on the structure controlling of In2S3 films were also discussed. The results show that the In2S3 nano-flower films consisted of ultrathin nanoflakes with a thickness of 5 nm are successfully grew on the surface of TiO2 nanorod arrays. PEG could play a role as the morphology-directing agent by confining crystal growth in certain directions, while PSS could provide coordination sites with long chains and lead to the formation of spherical structure. The energy conversion efficiency of In2S3 nano-flower/TiO2 photoelectrodes enhances thrice compared with that of bare TiO2 photoelectrode. This research presents further insight for improving the efficiency of semiconductors by using the suitable electron transfer channels, which may be promising for rational construction of solar conversion and storage devices.

  18. Fabrication of Al-Doped TiO2 Visible-Light Photocatalyst for Low-Concentration Mercury Removal

    Directory of Open Access Journals (Sweden)

    Cheng-Yen Tsai

    2012-01-01

    Full Text Available High-quality Al-doped TiO2 visible-light photocatalyst was prepared via a single-step direct combination of vaporized Ti, Al, and O2 using a 6 kW thermal plasma system. Results showed that the formed Al-doped TiO2 nanoparticles were a mixture of anatase and rutile phase and had a size between 10 and 105 nm. The absorption spectra of the nanoparticles shifted towards the visible light regions, depending on the Al2O3 addition. Ti4+ and Ti3+ coexisted in the synthesized Al-doped TiO2; the Ti3+ concentration, however, increased with increasing Al2O3 addition due to Al/Ti substitution that caused the occurrence of oxygen vacancy. Hg0 breakthrough tests revealed that the nanoparticles had an appreciable Hg0 removal under visible-light irradiation. Nevertheless, moisture reduced Hg removal by the nanoparticles, especially when visible-light irradiation was applied, suggesting that the competitive adsorption between H2O and Hg species on the active sites of TiO2 surface occurred.

  19. Fabrication of Heterogeneous TiO2-CdS Nanotubular Arrays on Transparent Conductive Substrate and Their Photoelectrochemical Properties

    Directory of Open Access Journals (Sweden)

    Jing Liu

    2015-11-01

    and the CdS nanoparticles under front-side illumination. Our strategy for nanotubular transfer on transparent substrate may extend the applications of TiO2 nanotubular arrays into other fields, such as dye-sensitized solar cells, photochromism and photocatalysis.

  20. WO3/CeO2/TiO2 Catalysts for Selective Catalytic Reduction of NO(x) by NH3: Effect of the Synthesis Method.

    Science.gov (United States)

    Michalow-Mauke, Katarzyna A; Lu, Ye; Ferri, Davide; Graule, Thomas; Kowalski, Kazimierz; Elsener, Martin; Kröcher, Oliver

    2015-01-01

    WO3/CeO2/TiO2, CeO2/TiO2 and WO3/TiO2 catalysts were prepared by wet impregnation. CeO2/TiO2 and WO3/TiO2 showed activity towards the selective catalytic reduction (SCR) of NO(x) by NH3, which was significantly improved by subsequent impregnation of CeO/TiO2 with WO3. Catalytic performance, NH3 oxidation and NH3 temperature programmed desorption of wet-impregnated WO3/CeO2/TiO2 were compared to those of a flame-made counterpart. The flame-made catalyst exhibits a peculiar arrangement of W-Ce-Ti-oxides that makes it very active for NH3-SCR. Catalysts prepared by wet impregnation with the aim to mimic the structure of the flame-made catalyst were not able to fully reproduce its activity. The differences in the catalytic performance between the investigated catalysts were related to their structural properties and the different interaction of the catalyst components.

  1. Fabrication of CoTiO3-TiO2 composite films from a heterobimetallic single source precursor for electrochemical sensing of dopamine.

    Science.gov (United States)

    Ehsan, Muhammad Ali; Naeem, Rabia; Khaledi, Hamid; Sohail, Manzar; Hakeem Saeed, Abbas; Mazhar, Muhammad

    2016-06-21

    Cobalt titanate-titania composite oxide films have been grown on FTO-coated glass substrates using a single-source heterometallic complex [Co2Ti4(μ-O)6(TFA)8(THF)6]·THF () which was obtained in quantitative yield from the reaction of diacetatocobalt(ii) tetrahydrate, tetraisopropoxytitanium(iv), and trifluoroacetic acid from a tetrahydrofuran solution. Physicochemical investigations of complex have been carried out by melting point, FT-IR, thermogravimetric and single-crystal X-ray diffraction analyses. CoTiO3-TiO2 films composed of spherical objects of various sizes have been grown from by aerosol-assisted chemical vapor deposition at different temperatures of 500, 550 and 600 °C. Thin films characterized by XRD, Raman and X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis have been explored for electrochemical detection of dopamine (DA). The cyclic voltammetry with the CoTiO3-TiO2 electrode showed a DA oxidation peak at +0.215 V while linear sweep voltammetry displayed a detection limit (LoD) of 0.083 μM and a linear concentration range of 20-300 μM for DA. Thus, the CoTiO3-TiO2 electrode is a potential candidate for the sensitive and selective detection of DA.

  2. Fabrication of transparent TiO2 nanotube-based photoanodes for CdS/CdTe quantum co-sensitized solar cells

    Science.gov (United States)

    Gualdrón-Reyes, A. F.; Cárdenas-Arenas, A.; Martínez, C. A.; Kouznetsov, V. V.; Meléndez, A. M.

    2017-01-01

    In order to fabricate a solar cell, ordered TiO2 nanotube (TNT) arrays were prepared by double anodization. TNT arrays with variable lengths were obtained by changing the duration of the anodizing process of up to 3h. TNT membranes were transferred to indium tin oxide substrates and attached with a B-TiO2 sol. TNT photoanode with the best photoelectrochemical performance was sensitized with CdS by SILAR method. On other hand, CdTe quantum dots prepared via colloidal synthesis were deposited on TNT photoanodes for 2h, 4h and 6h. In addition, TNT/CdS was loaded with CdTe quantum dots for 4 h. Morphology and chemical modification of TiO2 were characterized by FESEM and XPS, while their photoelectrochemical performance was measured by open-circuit photopotential and photovoltammetry under visible light. TiO2 nanotubes grown during 2.5h showed the highest photocurrent due to presence of Ti3+ donor states by N and F co-doping, increasing the number of photogenerated electrons transported to back collector. TNT/CdS/CdTe photoanode reach the highest conversion efficiency under AM 1.5G simulated solar illumination.

  3. In situ synthesis of TiO2/SnO(x)-Au ternary heterostructures effectively promoting visible-light photocatalysis.

    Science.gov (United States)

    Dong, Zhao; Wu, Minghua; Wu, Jiaying; Ma, Yuanyuan; Ma, Zhenzhen

    2015-07-14

    TiO2/SnOx-Au ternary heterostructures were successfully fabricated via a simple in situ reduction of AuCl4(-) on TiO2 surfaces pre-modified with Sn(2+). The samples were characterized by XRD, TEM, XPS, N2 physical absorption and UV-vis diffuse reflectance spectra. Photocatalytic activity toward degradation of methylene blue (MB) aqueous solution under visible light irradiation was investigated. The results suggested that the highly dispersive and ultrafine Au nanoparticles (NPs) covered with SnOx were deposited onto the surface of TiO2. The heterostructures significantly enhanced the photocatalytic activity compared with the traditional TiO2/Au sample prepared by the impregnation method and also enhanced the activity more than the binary TiO2/SnOx sample. Moreover, the size of the Au NPs could be well controlled by simply tuning the dosage of HAuCl4, and the optimized catalytic activity of the ternary heterostructures was obtained when the dosage of Au was 1% and the Au particle size was ∼2.65 nm. The enhancement of photocatalytic performance could be attributed to the surface plasmon resonance effect of the Au NPs and the electron-sink function of the SnOx, which improve the optical absorption properties as well as photoinduced charge carrier separation, synergistically facilitating the photocatalysis.

  4. Sequential Dip-spin Coating Method: Fully Infiltration of MAPbI 3-x Cl x into Mesoporous TiO 2 for Stable Hybrid Perovskite Solar Cells

    KAUST Repository

    Kim, Woochul

    2017-05-31

    Organic-inorganic hybrid perovskite solar cells (PSCs) have reached a power conversion efficiency of 22.1% in a short period (∼7 years), which has been obtainable in silicon-based solar cells for decades. The high power conversion efficiency and simple fabrication process render perovskite solar cells as potential future power generators, after overcoming the lack of long-term stability, for which the deposition of void-free and pore-filled perovskite films on mesoporous TiO2 layers is the key pursuit. In this research, we developed a sequential dip-spin coating method in which the perovskite solution can easily infiltrate the pores within the TiO2 nanoparticulate layer, and the resultant film has large crystalline grains without voids between them. As a result, a higher short circuit current is achieved owing to the large interfacial area of TiO2/perovskite, along with enhanced power conversion efficiency, compared to the conventional spin coating method. The as-made pore-filled and void-free perovskite film avoids intrinsic moisture and air and can effectively protect the diffusion of degradation factors into the perovskite film, which is advantageous for the long-term stability of PSCs.

  5. Application of TiO2 with different structures in solar cells

    Institute of Scientific and Technical Information of China (English)

    Zhang Tian-Hui; Piao Ling-Yu; Zhao Su-Ling; Xu Zheng; Wu Qian; Kong Chao

    2012-01-01

    The application of TiO2-based devices is mainly dependent on their crystalline structure,morphology,size,and exposed facets.Two kinds of TiO2 with different structures,namely TiO2 pompons and TiO2 nanotubes,have been prepared by the hydrothermal method.TiO2 with different structures is characterized by scanning electron microscopy (SEM),X-ray diffraction (XRD),and Brunauer-Emmett Teller (BET) surface area analysis.Solar cells based on poly(3-hexylthiophene) (P3HT) and TiO2 with different structures are fabricated.In the device ITO/TiO2/P3HT/Au,the P3HT is designed to act as the electron donor,and TiO2 pompons and TiO2 nanotubes act as the electron acceptor.The effects of the TiO2 structure on the performance of hybrid heterojunction solar cells are investigated.The device with TiO2 pompons has an open circuit voltage (Voc) of 0.51 V,a short circuit current (Jsc) of 0.21 mA/cm2,and a fill factor (FF) of 28.3%.Another device with TiO2 nanotubes has a Voc of 0.5 V,Jsc of 0.27 mA/cm2,and FF of 28.4%.The results indicate that the TiO2 nanotubes with a unidimensional structure have better carrier transport and light absorption properties than TiO2 pompons.Consequently,the solar cell based on TiO2 nanotubes has a better performance.

  6. Using measured 30-150 kVp polychromatic tungsten x-ray spectra to determine ion chamber calibration factors, Nx (Gy C(-1)).

    Science.gov (United States)

    Mercier, J R; Kopp, D T; McDavid, W D; Dove, S B; Lancaster, J L; Tucker, D M

    2000-10-01

    Two methods for determining ion chamber calibration factors (Nx) are presented for polychromatic tungsten x-ray beams whose spectra differ from beams with known Nx. Both methods take advantage of known x-ray fluence and kerma spectral distributions. In the first method, the x-ray tube potential is unchanged and spectra of differing filtration are measured. A primary standard ion chamber with known Nx for one beam is used to calculate the x-ray fluence spectrum of a second beam. Accurate air energy absorption coefficients are applied to the x-ray fluence spectra of the second beam to calculate actual air kerma and Nx. In the second method, two beams of differing tube potential and filtration with known Nx are used to bracket a beam of unknown Nx. A heuristically derived Nx interpolation scheme based on spectral characteristics of all three beams is described. Both methods are validated. Both methods improve accuracy over the current half value layer Nx estimating technique.

  7. Transparent TiO2 nanotube electrodes via thin layer anodization: fabrication and use in electrochromic devices.

    Science.gov (United States)

    Berger, S; Ghicov, A; Nah, Y-C; Schmuki, P

    2009-05-05

    In the present work, we describe an anodization process that is able to fully transform a thin Ti metal layer on a conductive glass into a TiO(2) nanotubular array. Under optimized conditions, nanotube electrodes can be obtained that are completely transparent and defect-free and allow electrochromic switching. These electrochromic electrodes show remarkable properties and can be directly integrated into devices.

  8. STUDI KOMPARASI SIFAT FOTOKATALIS DAN AGLOMERITAS NANOPARTIKEL TIO2 SEBAGAI PENGARUH DISPERSANT ETILEN GLIKOL DAN TRITON X 100 DALAM DIRT-FREE PAINT

    Directory of Open Access Journals (Sweden)

    Dyah Sawitri

    2014-05-01

    Full Text Available Telah dilakukan penelitian untuk mengetahui pengaruh variasi dispersant terhadap stabilitas fotokatalis dan aglomeritas nanopartikel TiO2 sebagai optimasi dirt-free paint, yaitu bahan komposit cat yang mempunyai sifat anti noda dan mampu membersihkan dirinya sendiri (self-cleaning dengan bantuan cahaya dan air. Dispersant yang digunakan Etilen Glikol dan Triton X 100. Komposisi massa TiO2 2% massa cat, dengan perbandingan anatase : rutile sebesar 90:10. Pengujian yang dilakukan meliputi uji DSC, XRD, FTIR, uji self-cleaning, dan SEM-EDX. Dari uji self-cleaning dengan dua macam pengotor, diperoleh hasil bahwa untuk pengotor lumpur, sampel terbaik adalah sampel dengan dispersant Etilen Glikol, dengan selisih luas pengotor 35,77%. Untuk pengotor pewarna makanan, sampel TiO2 dengan dispersant Triton X 100 memiliki selisih luas pengotor 17,64%. Hasil uji SEM-EDX menunjukkan ukuran partikel TiO2 rata-rata untuk cat tanpa dispersant adalah 132.02 nm, dan dengan dispersant Etilen Glikol menjadi 118.54 nm. Hasil pengujian menunjukkan bahwa bahan dispersant dapat menimbulkan sifat self cleaning, serta mampu mendispersikan TiO2 di dalam cat dengan baik.

  9. Photocatalytic self-cleaning cotton fabrics with platinum (IV) chloride modified TiO2 and N-TiO2 coatings

    Science.gov (United States)

    Long, Mingce; Zheng, Longhui; Tan, Beihui; Shu, Heping

    2016-11-01

    To enable photocatalytic self-cleaning cotton fabrics working under visible light irradiation, platinum (IV) chloride modified TiO2 (Pt-TiO2) and N-TiO2 (Pt-N-TiO2) nanosols are synthesized through a low temperature precipitation-peptization method. According to the characterizations of XRD, DRS and TEM, all nanoparticles are anatase nanocrystallites in the sizes of less than 10 nm, while N-TiO2 nanoparticles have better crystallization and smaller sizes. However, the cotton fabrics functionalized with Pt-TiO2 display significantly enhanced photocatalytic activity for methyl orange degradation and coffee stain removal under both solar simulator and visible light irradiation, while the performance of that coatings of Pt-N-TiO2 is poor. Further XRF and XPS results indicate that surface species on N-TiO2 block the adsorption of PtCl62- anions, whereas these anions strongly attach on the surface of TiO2 nanoparticles, and accordingly enable functionalized cotton fabrics efficient visible light driven activities based on a mechanism of charge transfer from ligand to metal (CTLM) excitation.

  10. Physical and electrical properties of band-engineered SiO2/(TiO2) x (SiO2)1- x stacks for nonvolatile memory applications

    Science.gov (United States)

    Oh, Jinho; Na, Heedo; Mok, In-Su; Kim, Jonggi; Lee, Kyumin; Sohn, Hyunchul

    2012-09-01

    In our study, the physical properties of (TiO2) x (SiO2)1- x , including band-gap, band-offset, and thermal stability and the electrical properties of band-engineered SiO2/(TiO2) x (SiO2)1- x tunnel barrier stacks, including the tunneling current and charge-trapping characteristics for applications to nonvolatile memory devices were investigated. It was observed that the band-gap and band-offset of (TiO2) x (SiO2)1- x can be controlled by adjustment in the composition of the (TiO2) x (SiO2)1- x films. Ti-silicate film with TiO2:SiO2 cycle ratio of 1:5 was maintained in an amorphous phase, even after annealing at 950 °C. The tunneling current of the band-engineered SiO2/(TiO2) x (SiO2)1- x stacked tunnel barrier was larger than that of a single SiO2 barrier under a higher external bias, while the tunneling current of a SiO2/(TiO2) x (SiO2)1- x stacked tunnel barrier under a lower external bias was smaller. Charge-trapping tests showed that the voltage shift for SiO2/(TiO2) x (SiO2)1- x is slightly larger than that for single SiO2.

  11. Fabrication of 3D interconnected porous TiO2 nanotubes templated by poly(vinyl chloride-g-4-vinyl pyridine) for dye-sensitized solar cells

    Science.gov (United States)

    Koh, Joo Hwan; Koh, Jong Kwan; Seo, Jin Ah; Shin, Jong-Shik; Kim, Jong Hak

    2011-09-01

    Porous TiO2 nanotube arrays with three-dimensional (3D) interconnectivity were prepared using a sol-gel process assisted by poly(vinyl chloride-graft-4-vinyl pyridine), PVC-g-P4VP graft copolymer and a ZnO nanorod template. A 7 µm long ZnO nanorod array was grown from the fluorine-doped tin oxide (FTO) glass via a liquid phase deposition method. The TiO2 sol-gel solution templated by the PVC-g-P4VP graft copolymer produced a random 3D interconnection between the adjacent ZnO nanorods during spin coating. Upon etching of ZnO, TiO2 nanotubes consisting of 10-15 nm nanoparticles were generated, as confirmed by wide-angle x-ray scattering (WAXS), energy-filtering transmission electron microscopy (EF-TEM) and field-emission scanning electron microscopy (FE-SEM). The ordered and interconnected nanotube architecture showed an enhanced light scattering effect and increased penetration of polymer electrolytes in dye-sensitized solar cells (DSSC). The energy conversion efficiency reached 1.82% for liquid electrolyte, and 1.46% for low molecular weight (Mw) and 0.74% for high Mw polymer electrolytes.

  12. An easy-to-fabricate low-temperature TiO2 electron collection layer for high efficiency planar heterojunction perovskite solar cells

    Directory of Open Access Journals (Sweden)

    B. Conings

    2014-08-01

    Full Text Available Organometal trihalide perovskite solar cells arguably represent the most auspicious new photovoltaic technology so far, as they possess an astonishing combination of properties. The impressive and brisk advances achieved so far bring forth highly efficient and solution processable solar cells, holding great promise to grow into a mature technology that is ready to be embedded on a large scale. However, the vast majority of state-of-the-art perovskite solar cells contains a dense TiO2 electron collection layer that requires a high temperature treatment (>450 °C, which obstructs the road towards roll-to-roll processing on flexible foils that can withstand no more than ∼150 °C. Furthermore, this high temperature treatment leads to an overall increased energy payback time and cumulative energy demand for this emerging photovoltaic technology. Here we present the implementation of an alternative TiO2 layer formed from an easily prepared nanoparticle dispersion, with annealing needs well within reach of roll-to-roll processing, making this technology also appealing from the energy payback aspect. Chemical and morphological analysis allows to understand and optimize the processing conditions of the TiO2 layer, finally resulting in a maximum obtained efficiency of 13.6% for a planar heterojunction solar cell within an ITO/TiO2/CH3NH3PbI3-xClxpoly(3-hexylthiophene/Ag architecture.

  13. Thin layer of ordered boron-doped TiO2 nanotubes fabricated in a novel type of electrolyte and characterized by remarkably improved photoactivity

    Science.gov (United States)

    Siuzdak, Katarzyna; Szkoda, Mariusz; Lisowska-Oleksiak, Anna; Grochowska, Katarzyna; Karczewski, Jakub; Ryl, Jacek

    2015-12-01

    This paper reports a novel method of boron doped titania nanotube arrays preparation by electrochemical anodization in electrolyte containing boron precursor - boron trifluoride diethyl etherate (BF3 C4H10O), simultaneously acting as an anodizing agent. A pure, ordered TiO2 nanotubes array, as a reference sample, was also prepared in solution containing a standard etching compound: ammonium fluoride. The doped and pure titania were characterized by scanning electron microscopy, UV-vis spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, photoluminescence emission spectroscopy and by means of electrochemical methods. The B-doping decidedly shifts the absorption edge of TiO2 nanotubes towards the visible light region and significantly inhibits the radiative recombination processes. Despite the fact that the doped sample is characterized by 4.6 lower real surface area when compared to pure titania, it leads to the decomposition of methylene blue in 93%, that is over 2.3 times higher than the degradation efficiency exhibited by the undoped material. The formation rate of hydroxyl radicals (rad OH) upon illumination significantly favours boron doped titania as a photocatalytic material. Moreover, the simple doping of TiO2 nanotubes array results in the enhancement of generated photocurrent from 120 μA/cm2 to 350 μA/cm2 registered for undoped and doped electrode, respectively.

  14. An easy-to-fabricate low-temperature TiO2 electron collection layer for high efficiency planar heterojunction perovskite solar cells

    Science.gov (United States)

    Conings, B.; Baeten, L.; Jacobs, T.; Dera, R.; D'Haen, J.; Manca, J.; Boyen, H.-G.

    2014-08-01

    Organometal trihalide perovskite solar cells arguably represent the most auspicious new photovoltaic technology so far, as they possess an astonishing combination of properties. The impressive and brisk advances achieved so far bring forth highly efficient and solution processable solar cells, holding great promise to grow into a mature technology that is ready to be embedded on a large scale. However, the vast majority of state-of-the-art perovskite solar cells contains a dense TiO2 electron collection layer that requires a high temperature treatment (>450 °C), which obstructs the road towards roll-to-roll processing on flexible foils that can withstand no more than ˜150 °C. Furthermore, this high temperature treatment leads to an overall increased energy payback time and cumulative energy demand for this emerging photovoltaic technology. Here we present the implementation of an alternative TiO2 layer formed from an easily prepared nanoparticle dispersion, with annealing needs well within reach of roll-to-roll processing, making this technology also appealing from the energy payback aspect. Chemical and morphological analysis allows to understand and optimize the processing conditions of the TiO2 layer, finally resulting in a maximum obtained efficiency of 13.6% for a planar heterojunction solar cell within an ITO/TiO2/CH3NH3PbI3-xClxpoly(3-hexylthiophene)/Ag architecture.

  15. Fabrication of Bi-Doped TiO2 Spheres with Ultrasonic Spray Pyrolysis and Investigation of Their Visible-Light Photocatalytic Properties

    Directory of Open Access Journals (Sweden)

    Jianhui Huang

    2012-01-01

    Full Text Available Bismuth-doped TiO2 submicrospheres were synthesized by ultrasonic spray pyrolysis. The prepared bismuth-doped titania was characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, UV-visible diffuse reflectance spectroscopy (UV-vis DRS, and X-ray photoelectron spectroscopy (XPS. Aqueous photocatalytic activity was evaluated by the decomposition of methyl orange under visible-light irradiation. The results indicate that doping of bismuth remarkably affects the phase composition, crystal structure, and the photocatalytic activity. The sample with 2% Bi exhibits the optimum photocatalytic activity.

  16. 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.

  17. Fabrication of a biomimetic ZeinPDA nanofibrous scaffold impregnated with BMP-2 peptide conjugated TiO2 nanoparticle for bone tissue engineering.

    Science.gov (United States)

    Sekar, Babitha; Annamalai, Meenakshi; Dykas, Michal Marcin; Saha, Surajit; Poddar, Kingshuk; Venugopal, Jayarama Reddy; Ramakrishna, Seeram; Venkatesan, Thirumalai; Korrapati, Purna Sai

    2017-09-04

    A biomimetic Zein polydopamine (PDA) based nanofiber scaffold was fabricated to deliver bone morphogenic protein-2 (BMP-2) peptide conjugated titanium dioxide (TiO2 ) nanoparticles in a sustained manner for investigating its osteogenic differentiation potential. To prolong its retention time at the target site, BMP-2 peptide has been conjugated to TiO2 nanoparticles owing to its high surface to volume ratio. The effect of biochemical cues from BMP-2 peptide and nano topographical stimulation of electrospun Zein PDA nanofibers were examined for its enhanced osteogenic expression of human fetal osteoblast (hFOB) cells. The sustained delivery of bioactive signals, improved cell adhesion, mineralization and differentiation could be attributed to its highly interconnected nanofibrous matrix with unique material composition. Further, the expression of osteogenic markers revealed that the fabricated nanofibrous scaffold possess better cell - biomaterial interactions. These promising results demonstrate the potential of the composite nanofibrous scaffold as an effective biomaterial substrate for bone regeneration. This article is protected by copyright. All rights reserved.

  18. Photochromic and self-cleaning properties of TiO2-AgCl/TiO2-xCu thin film.

    Science.gov (United States)

    Sangchay, Weerachai; Sikong, Lek; Kooptarnond, Kalayanee

    2013-02-01

    The TiO2-AgCl/TiO2-xCu thin films were prepared by sol-gel method and dip coated on glass slide. The prepared films were synthesized at the temperature of 400 degrees C for 2 h with a heating rate of 10 degrees C/min. The microstructure and properties of synthesized TiO2-AgCl/TiO2-xCu thin films were characterized by X-ray diffraction, scanning electron microscopy, atomic forced microscope and UV-vis diffuse reflectance spectroscopy. Finally, the hydrophilic property was evaluated by means of contact angle of water droplet on the films. The results show all samples have film thickness in range of 400-500 nm and their surfaces are dense and strong with a large surface area according to the image of atomic forced microscope. It can be noted that TiO2-AgCl/TiO2-5Cu thin films exhibit the highest photochromic (or the lowest capability of light transmittance) at 250-400 nm. The TiO2-AgCl/TiO2-xCu thin films can block UV C, UV B and UV A rays and exhibit self-cleaning effect (small contact angle, 3.9 degrees ) under UV irradiation.

  19. Enhancement of Electrical Properties of TiO2- x Oxide Semiconductor by d-Orbital Ordering Using Swift Heavy Ni-Ion Irradiation at Room Temperature

    Science.gov (United States)

    Cho, S. H.; Jun, B. H.; Chung, K. B.

    2017-02-01

    The electrical properties of radiofrequency (RF)-sputtered TiO2- x films have been investigated as a function of Ni-ion irradiation dose at room temperature. The prepared TiO2- x films were irradiated with 130-MeV swift heavy Ni ions in the range from 5 × 1011 ions/cm2 to 1 × 1013 ions/cm2. Increasing the Ni-ion irradiation dose dramatically enhanced the mobility in the TiO2- x films from 2.2 cm2/V s to 1.24 × 102 cm2/V s, while the carrier concentration did not vary. To explain this change in the electrical properties of the TiO2- x films, we investigated various physical properties, namely the physical structure, molecular orbital ordering in the conduction band, and shallow/deep trap states in the band-edge area below the conduction band. We suggest that the improvement in mobility originates from the ordering of the Ti 3 d orbital in the conduction band. In addition, increase of the Ni-ion irradiation dose changed two distinct band-edge states below the conduction band.

  20. Layer-by-layer fabrication of supramolecular dyes on TiO2 surfaces for optoelectronic applications

    Science.gov (United States)

    Kong, Xiaoqing; Maguire, Shawn; Lye, Diane; Weck, Marcus; Lee, Stephanie

    We present a modular layer-by-layer approach based on metal coordination chemistry to assemble supramolecular dyes exhibiting increased absorption in the visible range on electrode surfaces. Specifically, palladiated bis-pincer complexes (Pd-BPCs) were employed as linkers between pyridyl-terminated organic molecules via dative bonding. By alternately immersing mesoporous TiO2-coated glass substrates in solutions containing dissolved zinc porphyin (ZnP) and Pd-BPCs, supramolecular dyes were assembled layer-by-layer on the TiO2 surfaces. UV-visible absorption spectra of these assembled structures revealed a linear increase in the Soret and Q bands of ZnP after each immersion of the substrate in the ZnP solution. Coordination of the ZnP layers with Pd-BPC resulted in a slight red shift (organic molecules in specific layers of the supramolecular assemblies. By assembling unique organic dyes that absorb different wavelengths of light, we expect to expand light absorption across the visible region of the solar spectrum for solar cell applications.

  1. Fabrication of Fiber Bragg Grating Coating with TiO2 Nanostructured Metal Oxide for Refractive Index Sensor

    Directory of Open Access Journals (Sweden)

    Shaymaa Riyadh Tahhan

    2017-01-01

    Full Text Available To increase the sensitivity of biosensor a new approach using an optical fiber Bragg grating (FBG coated with a suitable nanostructured metal oxide (NMO is proposed which is costly effective compared to other biosensors. Bragg grating was written on a D-shaped optical fiber by phase mask method using a 248 nm KrF excimer laser for a 5 min exposure time producing a grating with a period of 528 nm. Titanium dioxide (TiO2 nanostructured metal oxide was coated over the fiber for the purpose of increasing its sensing area. The etched D-shaped FBG was then coated with 312 nm thick TiO2 nanostructured layer to ensure propagating the radiation modes within the core. The final structure was used to sense deionized water and saline. The etched D-shaped FBG original sensitivity before coating to air-deionized water and to air-saline was 0.314 nm/riu and 0.142 nm/riu, respectively. After coating the sensitivity became 1.257 nm/riu for air-deionized water and 0.857 nm/riu for air-saline.

  2. High-pressure synthesis and crystal structures of beta- M NX (M = Zr, Hf; X = Cl, Br, I)

    CERN Document Server

    Chen, X; Yamanaka, S

    2002-01-01

    The single crystals of six kinds of metal nitride halide, beta- M NX (M = Zr, Hf; X = Cl, Br, I), were grown in sealed Au (or Pt) tubes by the reaction of M N or M NX powders with NH sub 4 X as fluxes under high-temperature and high-pressure conditions such as 3-5 GPa at 900-1200 sup o C. The x-ray structure analysis revealed that all six kinds of compound crystallize in a rhombohedral space group R3-bar m, Z = 6. beta-ZrNCl, beta-ZrNBr, and beta-HfNCl are isotypic with SmSI, and the others isostructural with YOF.

  3. Formation Mechanistism Study of TiO2 Film Comprising Nanotubes and Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Di Yang; Yi-quan Wang; Guo-bin Ren; Shuai Feng; Yuan-yuan Chen; Wen-zhong Wang

    2012-01-01

    A novel titanium dioxide (TiO2) film comprising both nanotubes and nanopaticles was fabricated by an anodization process of the modified titanium.The local electric field at the anodized surface was simulated and its influence on the morphology of the TiO2 film was discussed.The results show that the electric field strength is enhanced by the covering.The growth rate of TiO2 increases with the assist of the local electric field.However,TiO2 dissolution is hindered since the local electric field prevents [TiF6]6- from diffusing.It means that the balance condition for the formation of nanotubes is broken,and TiO2 nanoparticles are formed.Moreover,the crystal structure of the TiO2 film was confirmed using X-ray diffraction and Raman analysis.The anatase is a main phase for the proposed film.

  4. Surface properties and biocompatibility of nanostructured TiO2 film deposited by RF magnetron sputtering.

    Science.gov (United States)

    Majeed, Asif; He, Jie; Jiao, Lingrui; Zhong, Xiaoxia; Sheng, Zhengming

    2015-01-01

    Nanostructured TiO2 films are deposited on a silicon substrate using 150-W power from the RF magnetron sputtering at working pressures of 3 to 5 Pa, with no substrate bias, and at 3 Pa with a substrate bias of -50 V. X-ray diffraction (XRD) analysis reveals that TiO2 films deposited on unbiased as well as biased substrates are all amorphous. Surface properties such as surface roughness and wettability of TiO2 films, grown in a plasma environment, under biased and unbiased substrate conditions are reported according to the said parameters of RF power and the working pressures. Primary rat osteoblasts (MC3T3-E1) cells have been cultured on nanostructured TiO2 films fabricated at different conditions of substrate bias and working pressures. The effects of roughness and hydrophilicity of nanostructured TiO2 films on cell density and cell spreading have been discussed.

  5. Synthesis of anatase and rutile TiO2 nanostructures from natural ilmenite

    Science.gov (United States)

    Wahyuingsih, Sayekti; Ramelan, Ari Handono; Pramono, Edi; Sulistya, Ariantama Djati; Argawan, Panji Rofa; Dharmawan, Frenandha Dwi; Rinawati, Ludfiaastu; Hanif, Qonita Awliya; Sulistiyono, Eko; Firdiyono, Florentinus

    2016-02-01

    Nanostructure anatase and rutile type TiO2 were synthesized from dissolution roasted ilmenite from natural ilmenite sand as the starting materials. Anatase TiO2 and rutile TiO2 (high crystallinity) with the diameters of 20-100 nm were obtained by calcined soluble ilmenite sand produced by leaching process. Calcinations of the xerogel TiO2 from liquor products were conducted for 4 hours at temperature of 450 °C. The samples were characterized by XRD (X-ray diffraction), STA (simultant thermal analysis), TEM (Transmission Electron Microscopy), and BET surface area. Titania Anatase-Rutile form as a mixture were produced by titania slag with the hydrolysis product. While, in another route, complete titania anatase phase was produced through hydrolysis and condensation steps of leach liquors. This synthesis methods provide a simple route to fabricate nanostructure TiO2 from low cost material.

  6. Engineering amorphous-crystalline interfaces in TiO2-x/TiO2-y-based bilayer structures for enhanced resistive switching and synaptic properties

    Science.gov (United States)

    Bousoulas, P.; Asenov, P.; Karageorgiou, I.; Sakellaropoulos, D.; Stathopoulos, S.; Tsoukalas, D.

    2016-10-01

    The operating principle of resistive random access memories (RRAMs) relies on the distribution of ionic species and their influence on the electron transport. Taking into account that formation and annihilation of conducting filaments (CFs) is the driving mechanism for the switching effect, it is very important to control the regions where these filaments will evolve. Thus, homolayers of titanium oxide with different oxygen contents were fabricated in order to tune the local electrical and thermal properties of the CFs and narrow down the potential percolation paths. We show that the oxygen content in the top layer of the TiO2-x/TiO2-y bilayer memristors can directly influence the morphology of the layers which affect the diffusion barrier and consequently the diffusivity and drift velocity of oxygen vacancies, yielding in important enhancement of switching characteristics, in terms of spatial uniformity (σ/μ < 0.2), enlarged switching ratio (˜104), and synaptic learning. In order to address the experimental data, a physical model was applied, divulging the crucial role of temperature, electric potential and oxygen vacancy density on the switching effect and offering physical insights to the SET/RESET transitions and the analog switching. The forming free nature of all the devices in conjunction with the self-rectifying behavior, should also be regarded as important assets towards RRAM device optimization.

  7. Comparison of photocatalytic properties of TiO2 thin films and fibers

    Science.gov (United States)

    Ozdemir, Mehtap; Kurt, Metin; Ozyuzer, Lutfi; Aygun, Gulnur

    2016-10-01

    Efficiency of solar panels degrades as a result of organic contamination such as airborne particles, bird droppings and leaves. Any foreign object on photovoltaic panels reduces the sunlight entering the absorbing surface of the solar panels. Since this leads to a major problem decreasing in energy production, solar panels should be cleaned. The self-cleaning method can be preferred. There are some methods to clean the surface of solar panels. Among the self-cleaning materials, TiO2 is the most preferable ones because of its powerful photocatalytic properties. In this study, photocatalytic TiO2 were produced in two different nanostructures: nanofibers and thin films. TiO2 nanofibers were successfully produced by electrospinning. TiO2 thin films were fabricated by reactive magnetron sputtering technique. Both TiO2 nanofiber and thin film structures were heat-treated to form TiO2 in anatase phase at 600 °C for 2 h in air. Then, they were evaluated by SEM analyses for morphology, X-ray diffraction (XRD) analyses for phase structures, X-ray photoelectron spectroscopy (XPS) for the chemical state and atomic concentration, and UV-spectrometer for photocatalytic performance. The results indicate that photocatalytic and transmittance properties of TiO2 thin films are better than those of nanofibers. Consequently, TiO2 based thin films exhibit better performance for solar cell applications due to the surface cleanliness.

  8. A generic and facile strategy to fabricate metal-organic framework films on TiO2 substrates for photocatalysis.

    Science.gov (United States)

    Yang, Huimin; Fei, Honghan

    2017-02-28

    We present a facile and compelling method for the synthesis of metal-organic framework (MOF) thin films on TiO2-coated conductive glass substrates. This generic deposition approach is extended to five representative MOF films (e.g. UiO, MIL, IRMOF, and NU series) with high crystallinity and excellent surface coverage, achieving a MOF/TiO2 heterostructure interface. The tunable thickness and functionality of MOF films as well as the preferred orientation of MOF microcrystallites are described. After the incorporation of [Ru(bpy)3](2+) functionality via postsynthetic ligand exchange, the resultant MOF films serve as a robust and efficient catalyst for photo-oxidation of thioanisole. Importantly, our deposition technique avoids the direct contact between solid MOF catalysts and magnetic stirring, thus overcoming the problem that the vast majority of MOF powder catalysts are subject to defragmentation or decomposition under the physical treatment methods.

  9. Fabrication and application of mesoporous TiO2 film coated on Al wire by sol-gel method with EISA

    Science.gov (United States)

    Zhao, Linkang; Lu, Jianjun

    2017-04-01

    Mesoporous TiO2 film on Al wire was fabricated by sol-gel method with evaporation induced self assembly (EISA) process using F127 as templating agent in the mixed solution of ethanol and Tetra-n-butyl Titanate. The Ni/TiO2 film catalyst supported on Al wire was prepared by impregnation and the catalytic performance on methanation was carried out in a titanium alloy micro-reactor tube. It was shown that anatase mesoporous TiO2 film was prepared in this conditions (1 g F127,calcined at 400 °C and aged for 24 h), which has specific surface area of 127 m2 g-1 and narrow pore size distribution of 5.3 nm. Low calcined temperature (300 °C) cannot transfer film to anatase and decompose F127 completely. Ni/TiO2 film on Al wire catalyst was proved to be active in CO methanation reaction. And the CO conversion reaches 99% and CH4 selectivity close is to 80% when the reaction temperature is higher 360 °C.

  10. Fabrication of TiO2 Nanotube Arrays on Si Substrates%硅基底TiO2纳米管阵列的制备

    Institute of Scientific and Technical Information of China (English)

    杨铭杰; 刘伟; 孙家林

    2012-01-01

    本文采用磁控溅射方法在硅基底上沉积一层金属钛膜,用于取代传统阳极氧化法制备TiO2纳米管阵列所用的金属钛片.分别在乙二醇和丙三醇两种电解液中进行阳极氧化,均在硅基底上形成了高度有序的TiO2纳米管阵列.该方法与硅工艺集成技术兼容,有利于基于TiO2纳米管阵列的微纳米器件的设计和制造.%Titanium films deposited on Si substrates by magnetron sputtering were used instead of titanium foils in the traditional anodizing process. Highly-ordered TiO2 nanotube arrays were fabricated on Si substrates via anodiza-tion in ethylene glycol electrolyte and glycerol electrolyte, respectively. This method was compatible with silicon integration technology, which was in favor of the design and manufacture of micro-nano devices based on TiO2 nanotube arrays

  11. Incorporation of N-doped TiO2 nanorods in regenerated cellulose thin films fabricated from recycled newspaper as a green portable photocatalyst.

    Science.gov (United States)

    Mohamed, Mohamad Azuwa; Salleh, W N W; Jaafar, Juhana; Ismail, A F; Abd Mutalib, Muhazri; Jamil, Siti Munira

    2015-11-20

    In this work, an environmental friendly RC/N-TiO2 nanocomposite thin film was designed as a green portable photocatalyst by utilizing recycled newspaper as sustainable cellulose resource. Investigations on the influence of N-doped TiO2 nanorods incorporation on the structural and morphological properties of RC/N-TiO2 nanocomposite thin film are presented. The resulting nanocomposite thin film was characterized by FESEM, AFM, FTIR, UV-vis-NIR spectroscopy, and XPS analysis. The results suggested that there was a remarkable compatibility between cellulose and N-doped TiO2 nanorods anchored onto the surface of the RC/N-TiO2 nanocomposite thin film. Under UV and visible irradiation, the RC/N-TiO2 nanocomposite thin film showed remarkable photocatalytic activity for the degradation of methylene blue solution with degradation percentage of 96% and 78.8%, respectively. It is crucial to note that the resulting portable photocatalyst produced via an environmental and green technique in its fabrication process has good potential in the field of water and wastewater treatment application. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Enhanced thermo-mechanical performance and strain-induced band gap reduction of TiO2@PVC nanocomposite films

    Indian Academy of Sciences (India)

    Mudassir Hasan; Arghya Narayan Banerjee; Moonyong Lee

    2015-04-01

    The present paper reports the fabrication of TiO2@PVC nanocomposites by incorporating TiO2 in polyvinyl chloride (PVC) followed by solution casting to prepare TiO2@PVC nanocomposite thin films. The asprepared TiO2@PVC nanocomposite films were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy, thermogravimetric analysis, optical spectroscopy and mechanical strength analyses. The TiO2@PVC nanocomposites were found to be thermally and mechanically more stable compared with pure PVC. The anatase TiO2 in the TiO2@PVC nanocomposite showed a lower indirect band gap compared with pure TiO2, which can be attributed to the strain within the nanocomposite, thereby affecting the band-structure of the nanocomposite. Significant enhancement in the mechanical properties of TiO2@PVC compared with pure PVC was observed with a 10 wt% TiO2 loading, such as a 50% increase in Young's modulus and almost 100% improvement in the tensile strength.

  13. Preparation of Smooth Surface TiO2 Photoanode for High Energy Conversion Efficiency in Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Sasipriya Kathirvel

    2013-01-01

    Full Text Available Dye-sensitized solar cells (DSSCs based on a TiO2 photoanode have been considered as an alternative source in the field of renewable energy resources. In DSSCs, photoanode plays a key role to achieve excellent photo-to-electric conversion efficiency. The surface morphology, surface area, TiO2 crystal phase, and the dispersion of TiO2 nanoparticles are the most important factors influencing the properties of a photoanode. The smooth TiO2 surface morphology of the photoanode indicates closely packed arrangement of TiO2 particles which enhance the light harvesting efficiency of the cell. In this paper, a smooth TiO2 photoanode has been successfully prepared using a well-dispersed anatase TiO2 nanosol via a simple hydrothermal process. The above TiO2 photoanode was then compared with the photoanode made from commercial TiO2 nanoparticle pastes. The morphological and structural analyses of both the aforementioned photoanodes were comprehensively characterized by scanning electron microscopy and X-ray diffraction analysis. The DSSC fabricated by using a-TiO2 nanosol-based photoelectrode exhibited an overall light conversion efficiency of 7.20% and a short-circuit current density of 13.34 mA cm−2, which was significantly higher than those of the DSSCs with the TiO2 nanoparticles-based electrodes.

  14. Low-cost fabrication of highly sensitive room temperature hydrogen sensor based on ordered mesoporous Co-doped TiO2 structure

    Science.gov (United States)

    Li, Zhong; Haidry, Azhar Ali; Wang, Tao; Yao, Zheng Jun

    2017-07-01

    The development of cost-effective gas sensors with improved sensing properties and minimum power consumption for room temperature hydrogen leakage monitoring is in increasing demand. In this context, this report focus on the facile fabrication of ordered mesoporous TiO2 via evaporation-induced self-assembly route. With the controlled doping threshold (3%Co-TiO2), the output resistance change to 1000 ppm H2 is ˜4.1 × 103 with the response time of 66 s. The sensor response exhibits power law dependence with an increase in the hydrogen concentration, where the power law coefficient was found not only specific to the kind of target gas but also related to temperature. Further, the effect of structure integrity with doping level and humidity on sensing characteristics is interpreted in terms of variation in surface potential eVS and depletion region w caused by the adsorption of molecular oxygen O2-.

  15. Crystal, electronic and luminescence properties of Eu2+-doped Sr2Al2−xSi1+xO7−xNx

    Directory of Open Access Journals (Sweden)

    Yuan Qiang Li, Naoto Hirosaki, Rong-Jun Xie and Mamoru Mitomo

    2007-01-01

    Full Text Available The crystal and electronic structures, as well as the luminescence properties of Sr2Al2−xSi1+xO7−xNx:Eu2+ are reported. First-principles calculations energetically confirm that the Al and Si atoms are in partial ordering in the 2a and 4e sites in Sr2Al2SiO7. In addition, the band structure calculation shows that Sr2Al2SiO7 has an indirect band gap with an energy gap of about 4.07 eV, which is in good agreement with the experimental data (~5.3 eV obtained from the diffuse reflection spectrum. The crystal structure of Sr2Al2SiO7 can be modified by Si–N substitution for Al–O in the lattice with a maximum solubility of about x=0.6. The average bond length of EuSr-(O,N slightly increases although the lattice parameters decrease with the incorporation of Si–N in Sr2Al2SiO7:Eu2+. Under excitation in the visible spectral region, Sr2Al2−xSi1+xO7−xNx:Eu2+ emits blue to yellow light with a broad emission band in the range of 480–570 nm, varying with both the Eu concentration and the x value. The red shift of the emission band of Eu2+ is associated with an increase in the crystal-field splitting and the covalency, which arise from the incorporation of nitrogen as well as the energy transfer between the Eu ions at high Eu concentrations. Moreover, the Eu ions have a strong effect on both the concentration quenching and the thermal quenching in Sr2Al2−xSi1+xO7−xNx. The temperature dependence of photoluminescence indicates that Sr2Al2−xSi1+xO7−xNx:Eu2+ shows strong thermal quenching due to the dominant nonradiative process at room temperature.

  16. Superhydrophobic cotton fabrics prepared by sol–gel coating of TiO2 and surface hydrophobization

    Directory of Open Access Journals (Sweden)

    Chao-Hua Xue et al

    2008-01-01

    Full Text Available By coating fibers with titania sol to generate a dual-size surface roughness, followed by hydrophobization with stearic acid, 1H,1H,2H,2H-perfluorodecyltrichlorosilane or their combination, hydrophilic cotton fabrics were made superhydrophobic. The surface wettability and topology of cotton fabrics were studied by contact angle measurement and scanning electron microscopy. The UV-shielding property of the treated fabrics was also characterized by UV-vis spectrophotometry.

  17. Fabrication of TiO2 Nanofilms by Ti+ Ion Implantation and Subsequent Thermal Annealing%Ti+离子注入结合热退火法制备TiO2纳米薄膜研究

    Institute of Scientific and Technical Information of China (English)

    周小东

    2015-01-01

    利用金属蒸发真空多弧离子源(MEVVA源)注入机将Ti+离子注入到高纯石英玻璃衬底中,离子注入的加速电压为20 kV,注入剂量为1.5×1017和3×1017 ions/cm2,将注入样品在氧气气氛下进行热退火处理,制备了TiO2纳米薄膜。采用光吸收谱、拉曼光谱、X射线光电子能谱、扫描电子显微镜和透射电子显微镜对注入样品进行了测试和表征,分析了TiO2薄膜的形成机理。在热退火过程中衬底中离子注入的Ti原子向外扩散到衬底表面被氧化形成了TiO2。TiO2的形成、晶粒尺寸和晶体结构依赖于热退火温度,而形成TiO2薄膜的厚度主要受离子注入剂量和热退火时间的影响。实验结果表明,该方法制备的TiO2纳米薄膜将有望应用于制备具有光催化、自清洁等特殊性能的自清洁玻璃。%TiO2 nanofilms on the surface of fused silica have been fabricated by Ti+ ion implantation and subsequent thermal annealing in oxygen ambience. The silica glasses were implanted by Ti+ ions at 20 kV with fluences of 1.5 and 3×1017 ions/cm2 using a metal vapor vacuum arc (MEVVA) ion source implanter. The optical absorption spectroscopy, Raman scattering spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) measurements were done to figure out formation mechanism of the TiO2 nanofilms. The formation of TiO2 nanofilms resulted from out-diffusion of the implanted Ti ions to the substrate surface, where they were oxidized intoTiO2. The formation, grain size and the crystallographic phase of TiO2 are annealing temperature dependent, and TiO2 nanofilm thickness can be well tailored by controlling the implantation fluence and annealing time. Results show that the TiO2 nanofilms fabricated by this novel method have great potential in applications such as photocatalytic, antibacterial and self-cleaning glass.

  18. Improvement of Capacity and Cycling Performance of Spinel LiMn2O4 Cathode Materials with TiO2-B Nanobelts

    DEFF Research Database (Denmark)

    Zhang, J.Y.; Shen, J.X.; Wang, T.L.;

    2013-01-01

    The spinel LiMn2O4 was modified with TiO2-B nanobelts to improve its specific capacity and cycling performance. TiO2-B/LiMn2O4 composites were fabricated by a facile liquid phase mixing method. The morphology and structure of the samples were characterized by means of X-ray diffraction, scanning ...

  19. Improved conversion efficiency of dye sensitized solar cell using Zn doped TiO2-ZrO2 nanocomposite

    Science.gov (United States)

    Tomar, Laxmi J.; Bhatt, Piyush J.; Desai, Rahul K.; Chakrabarty, B. S.; Panchal, C. J.

    2016-05-01

    TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites were prepared by hydrothermal method for dye sensitized solar cell (DSSC) application. The structural and optical properties were investigated by X -ray diffraction (XRD) and UV-Visible spectroscopy respectively. XRD results revealed the formation of material in nano size. The average crystallite size is 22.32 nm, 17.41 nm and 6.31 nm for TiO2, TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites respectively. The optical bandgap varies from 2.04 eV to 3.75 eV. Dye sensitized solar cells were fabricated using the prepared material. Pomegranate juice was used as a sensitizer and graphite coated conducting glass plate was used as counter electrode. The I - V characteristics were recorded to measure photo response of DSSC. Photovoltaic parameter like open circuit voltage, power conversion efficiency, and fill factor were evaluated for fabricated solar cell. The power conversion efficiency of DSSC fabricated with TiO2, TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites were found 0.71%, 1.97% and 4.58% respectively.

  20. Natural dye sensitized TiO2 nanorods assembly of broccoli shape based solar cells.

    Science.gov (United States)

    Yuvapragasam, Akila; Muthukumarasamy, N; Agilan, S; Velauthapillai, Dhayalan; Senthil, T S; Sundaram, Senthilarasu

    2015-07-01

    TiO2 nanorods based thin films with rutile phase have been synthesized using template free low temperature hydrothermal method. The scanning electron microscope images showed that the prepared TiO2 samples were made of TiO2 nanorods and the nanorods had arranged by itself to form a broccoli like shape. The X-ray diffraction studies revealed that the prepared TiO2 samples exhibit rutile phase. The grown TiO2 nanorods had been sensitized using the flowers of Sesbania (S) grandiflora, leaves of Camellia (C) sinensis and roots of Rubia (R) tinctorum. Dye sensitized solar cells had been fabricated using the natural dye sensitized TiO2 nanorods based thin film photoelectrode and the open circuit voltage and short circuit current density were found to lie in the range of 0.45-0.6 V and 5.6-6.4 mA/cm(2) respectively. The photovoltaic performance of all the fabricated natural dye sensitized TiO2 solar cells indicate that natural dyes have the potential to be used as effective sensitizer in dye sensitized solar cells.

  1. High-Performance Si/SiOx Nanosphere Anode Material by Multipurpose Interfacial Engineering with Black TiO(2-x).

    Science.gov (United States)

    Bae, Juhye; Kim, Dae Sik; Yoo, Hyundong; Park, Eunjun; Lim, Young-Geun; Park, Min-Sik; Kim, Young-Jun; Kim, Hansu

    2016-02-01

    Silicon oxides (SiOx) have attracted recent attention for their great potential as promising anode materials for lithium ion batteries as a result of their high energy density and excellent cycle performance. Despite these advantages, the commercial use of these materials is still impeded by low initial Coulombic efficiency and high production cost associated with a complicated synthesis process. Here, we demonstrate that Si/SiOx nanosphere anode materials show much improved performance enabled by electroconductive black TiO(2-x) coating in terms of reversible capacity, Coulombic efficiency, and thermal reliability. The resulting anode material exhibits a high reversible capacity of 1200 mAh g(-1) with an excellent cycle performance of up to 100 cycles. The introduction of a TiO(2-x) layer induces further reduction of the Si species in the SiOx matrix phase, thereby increasing the reversible capacity and initial Coulombic efficiency. Besides the improved electrochemical performance, the TiO(2-x) coating layer plays a key role in improving the thermal reliability of the Si/SiOx nanosphere anode material at the same time. We believe that this multipurpose interfacial engineering approach provides another route toward high-performance Si-based anode materials on a commercial scale.

  2. Photovoltaic performances of Cu2-xTe sensitizer based on undoped and indium(3+)-doped TiO2 photoelectrodes and assembled counter electrodes.

    Science.gov (United States)

    Srathongluan, Pornpimol; Kuhamaneechot, Rattanakorn; Sukthao, Prapatsawan; Vailikhit, Veeramol; Choopun, Supab; Tubtimtae, Auttasit

    2016-02-01

    Novel binary Cu2-xTe nanoparticles based on undoped and indium-doped TiO2 photoelectrodes were synthesized using a successive ionic layer adsorption and reaction (SILAR) technique as a sensitizer for liquid-junction solar cells. A larger diameter of TiO2 promoted a narrower energy band gap after indium doping, attributing to yield a broader absorption range of nanoparticle sensitizer due to the increasing amount of Cu2-xTe NPs on TiO2 surface. The atomic percentages showed the stoichiometric formation of Cu2Te incorporated in a Cu2-xTe structure. The best photovoltaic performance with the lower SILAR cycle, i.e., n=13 was performed after indium doping in both of carbon and Cu2S CEs and revealed that the efficiency of 0.73% under the radiant 100mW/cm(2) (AM 1.5G). The electrochemical impedance spectroscopy (EIS) was used to investigate the electrical properties via effect of material doping and counter electrodes with a lower charge-transfer resistance (Rct) and it was also found that the electron lifetime was improved after the sample doped with indium and assembled with carbon CE.

  3. Utilization of N-X bonds in the synthesis of N-heterocycles.

    Science.gov (United States)

    Minakata, Satoshi

    2009-08-18

    Nitrogen-containing heterocycles--such as aziridines, pyrrolidines, piperidines, and oxazolines--frequently show up as substructures in natural products. In addition, some of these species show potent biological activities. Therefore, researchers would like to develop practical and convenient methods for constructing these heterocycles. Among the available methods, the transfer of N(1) units to organic molecules, especially olefins, is a versatile method for the synthesis of N-heterocycles. This Account reviews some of our recent work on the synthesis of N-heterocycles using the N-X bond. A nitrogen-halogen bond bearing an electron-withdrawing group on the nitrogen can be converted to a halonium ion. In the presence of C-C double bonds, these species produce three-membered cyclic halonium intermediates, which can be strong electrophiles and can produce stereocontrolled products. N-Halosuccinimides are representative sources of halonium ions, and the nitrogen of succinimide is rarely used in organic synthesis. If the nitrogen could act as a nucleophile, after releasing halonium ions to C-C double bonds, we expect great advances would be possible in the stereoselective functionalization of olefins. We chose N-chloro-N-sodio-p-toluenesulfonamide (chloramine-T, CT), an inexpensive and commercially available reagent, as our desired reactant. In the presence of a catalytic amount of CuCl or I(2) and AgNO(3), we achieved the direct aziridination of olefins with CT. The reaction catalyzed by I(2) could be carried out in water or silica-water as a green process. The reaction of iodoolefins with CT gave pyrrolidine derivatives under extremely mild conditions with complete stereoselectivity. We also extended the utility of the N-chloro-N-metallo reagent, which is often unstable and difficult to work with. Although CT does not react with electron-deficient olefins without a metal catalyst or an additive, we found that N-chloro-N-sodiocarbamates react with electron

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

    Science.gov (United States)

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

    2015-03-01

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

  5. The effect of light-scattering layer on the performance of dye-sensitized solar cell assembled using TiO2 double-layered films as photoanodes

    Science.gov (United States)

    Zhu, L.; Zhao, Y. L.; Lin, X. P.; Gu, X. Q.; Qiang, Y. H.

    2014-01-01

    Dye-sensitized solar cells (DSSCs) are fabricated based on double-layered films of TiO2 nanospheres and TiO2 nanorod arrays (NRAs). TiO2 nanospheres, including TiO2 hollow spheres (HSs) and TiO2 solid spheres (SSs), were served as light-scattering layers on TiO2 NRAs as composite photoanodes. The as-prepared TiO2 NRAs, TiO2 HSs and TiO2 SSs have been characterized by field emission scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The photoelectric properties of DSSCs were investigated by UV-vis reflectance spectra, current-voltage curves and electrochemical impedance spectroscopy. Owing to the synergic effects of the TiO2 HSs (SSs) and NRAs, including large specific surface area of HSs (SSs) as light-scattering layer for effective dye adsorption and harvesting light and rapid electron transport in one dimensional TiO2 NRAs, the optimal energy conversion efficiency of DSSCs with as-prepared double-layered films as nanocomposite photoanode (5.40%) were far higher than the ones using single-layered NRAs films (1.56%).

  6. One-dimensional Z-scheme TiO2/WO3/Pt heterostructures for enhanced hydrogen generation

    Science.gov (United States)

    Gao, Hongqing; Zhang, Peng; Hu, Junhua; Pan, Jimin; Fan, Jiajie; Shao, Guosheng

    2017-01-01

    One-dimensional Z-scheme TiO2/WO3/Pt heterostructures were fabricated by integrating a facile electrospinning technique and subsequent annealing in air. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy, were used to characterize the as-fabricated samples. The results showed that the H2-generation of the as-fabricated one-dimensional Z-scheme TiO2/WO3/Pt heterostructures (S2) was greatly enhanced compared with pure TiO2 nanofibers (S0) and TiO2/WO3 nanofibers (S1). The enhanced photocatalyst activities were mainly attributed to the solid-state Z-scheme photosynthetic heterojunction system with Pt nanoparticle as an electron collector and WO3 as a hole collector, leading to effective charge separation on these semiconductors, which were evidenced by electrochemical impedance spectroscopy (EIS) and photocurrent analysis.

  7. Thiourea-Modified TiO2 Nanorods with Enhanced Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    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.

  8. Thiourea-Modified TiO2 Nanorods with Enhanced Photocatalytic Activity.

    Science.gov (United States)

    Wu, Xiaofeng; Fang, Shun; Zheng, Yang; Sun, Jie; Lv, Kangle

    2016-02-01

    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.

  9. X-TiO2(X=Ce,Bi)粉体的光电催化性能的研究%Study on Photoelectrocatalytic Performance of X- TiO2 (X=Ce, Bi) Powder

    Institute of Scientific and Technical Information of China (English)

    黄长萍; 鲁道荣; 燕逸飞

    2012-01-01

    采用溶胶-凝胶法制备出纳米X- TiO2(X=Ce,Bi)粉体,并用XRD、UV-Vis DRS对其进行表征,以500W氙灯模拟太阳光,考察改性TiO2粉体的可见光催化活性.采用涂覆法制备出改性TiO2电极,以300W高压汞灯为侧光源,考察了电极的光电催化性能.实验结果表明:改性TiO2粉体均为锐钛矿型晶相,Ce和Bi的加入不同程度地提高了TiO2在可见光区的吸光强度,Bi和Ce最佳摩尔掺杂量均为0.04%.3种电极光电催化性能先后排序为:TiO2电极<0.04%Bi-TiO2电极<0.04%Ce-TiO2电极,循环伏安曲线分析表明,金属离子的掺杂提高了TiO2电极的电催化活性,且Ce的掺杂对电极电催化活性的影响大于Bi.HPLC分析表明,金属离子掺杂使得苯环开环加速,促进了苯酚的氧化过程.%X- TiO2(X=Ce, Bi) nanomaterials were prepared by sol-gel method, and characterized by X-ray diffraction and UV-Vis diffuse reflectance spectroscopy. With 500W xenon lamp as simulated sunlight, the visible photo-catalytic activities of the modified TiO2 powder were evaluated. The photoelectrocatalytic performance of doped TiO2 electrodes prepared by coating technique was studied under ultraviolet excitation. The results indicate that the doped TiC>2 nanopowder exhibit anatase phase. Compared with pure TiO2 , the Ce-TiO2 and Bi-TiO2 show stronger absorption for visible light and higher activities for degradation of phenol in aqueous solution under visible light(A>400 nm) irradiation. The optimum doping concentrations of Bi and Ce are 0. 04% and 0. 04 % (molar ratio) respectively. Photoelectrocatalytic performance of the three TiO2 electrodes lies in: TiO2 < 0. 04 % Bi-TiO2<0. 04 % Ce-TiO2. Cyclic voltammogram analysis show that metal ion doping improve the electrocatalytic activity of TiO2 electrode, and the electrode with Ce doping is superior to Bi doping. The HPLC analysis results declare that metal ion doping accelerate benzene ring opening and enhance the phenol oxidation.

  10. Anatase TiO2 pillar-nanoparticle composite fabricated by layer-by-layer assembly for high-efficiency dye-sensitized solar cells.

    Science.gov (United States)

    Zhang, Guoliang; Pan, Kai; Zhou, Wei; Qu, Yang; Pan, Qingjing; Jiang, Baojiang; Tian, Guohui; Wang, Guofeng; Xie, Ying; Dong, Youzhen; Miao, Xiaohuan; Tian, Chungui

    2012-11-07

    The anatase TiO(2) pillar (PL)-TiO(2) nanoparticle (NP) composite is fabricated via layer-by-layer assembly. The composition of the nanostructures (i.e. the pillar-to-nanoparticle ratio) can be conveniently tuned by controlling the experimental conditions of the layer-by-layer assembly. It has been used to fabricate photoelectrodes for high-efficiency dye-sensitized solar cells (DSSCs), which combine the advantages of the rapid electron transport in PLs with the high surface area of NPs. It was found that, with optimum preparation conditions, DSSCs with the composite photoelectrode show a better photoelectrical conversion efficiency (8.06%) than those with either the naked PL photoelectrode or the mechanically mixed PL-NP photoelectrode. This is explained by the photoelectron injection drive force and the interfacial electron transport of the DSSCs, which are quantitatively characterized using the surface photovoltage spectra and electrochemical impedance spectroscopy measurements. It is evident that the DSSC with the optimal PL/NP ratio displays the largest photoelectron injection drive force and the fastest interfacial electron transfer.

  11. Effect of substituents on the strength of N-X (X = H, F, and Cl) bond dissociation energies: a high-level quantum chemical study.

    Science.gov (United States)

    O'Reilly, Robert J; Karton, Amir; Radom, Leo

    2011-06-02

    The effect of substituents on the strength of N-X (X = H, F, and Cl) bonds has been investigated using the high-level W2w thermochemical protocol. The substituents have been selected to be representative of the key functional groups that are likely to be of biological, synthetic, or industrial importance for these systems. We interpreted the effects through the calculation of relative N-X bond dissociation energies (BDE) or radical stabilization energies (RSE(NX)). The BDE and RSE(NX) values depend on stabilizing/destabilizing effects in both the reactant molecule and the product radical of the dissociation reactions. To assist us in the analysis of the substituent effects, a number of additional thermochemical quantities have been introduced, including molecule stabilization energies (MSE(NX)). We find that the RSE(NH) values are (a) increased by electron-donating alkyl substituents or the vinyl substituent, (b) increased in imines, and (c) decreased by electron-withdrawing substituents such as CF(3) and carbonyl moieties or through protonation. A different picture emerges when considering the RSE(NF) and RSE(NCl) values because of the electronegativities of the halogen atoms. The RSE(NX)s differ from the RSE(NH) values by an amount related to the stabilization of the N-halogenated molecules and given by MSE(NX). We find that substituents that stabilize/destabilize the radicals also tend to stabilize/destabilize the N-halogenated molecules. As a result, N-F- and N-Cl-containing molecules that include alkyl substituents or correspond to imines are generally associated with RSE(NF) and RSE(NCl) values that are less positive or more negative than the corresponding RSE(NH). In contrast, N-F- and N-Cl-containing molecules that include electron-withdrawing substituents or are protonated are generally associated with RSE(NF) and RSE(NCl) values that are more positive or less negative than the corresponding RSE(NH).

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

    Science.gov (United States)

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

    2013-09-21

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

  13. Nanolayer-transfer method of TiO2 slot layers and its application for fabricating hybrid electro-optic polymer/TiO2 vertical slot waveguide modulators

    Science.gov (United States)

    Jouane, Youssef; Enami, Yasufumi

    2017-09-01

    We have presented a alternative soft process named nanolayer transfer (NLT), to fabricate hybrid electro-optic polymer/TiO2 vertical slot waveguide modulators. We have transfered successfully a 100 nm thick TiO2 line pattern layer on sol-gel silica cladding layer, and at the same time we have created a line waveguide in sol-gel silica cladding layer with the widths up to 1 μ m. The sol-gel silica layer is hydrolyzed and cross-linked, creating a SiO2 network with a highly oriented polycrystalline film of TiO2 in which all crystals grow in the main preferential direction. NLT method also enables to control the high refractive index with better crystallization and lower optical propagation loss of transferred TiO2 slot layer, which allows us to have a higher optical mode confinement of EO polymer ensuring the feasibility of the EO device modulators.

  14. Development of TiO2 electrical insulation coating on Ag-alloy sheathed Bi2Sr2CaCu2O8-x round-wire

    Science.gov (United States)

    Kandel, H.; Lu, J.; Jiang, J.; Chen, P.; Matras, M.; Craig, N.; Trociewitz, U. P.; Hellstrom, E. E.; Larbalestier, D. C.

    2015-03-01

    We have developed TiO2 coating on Ag-alloy sheathed Bi2Sr2CaCu2O8-x (Bi-2212) round-wire conductor for electrical insulation in Bi-2212 magnets. The green coating has a base layer comprised of TiO2, polyvinyl butyral (PVB) and a small amount of polysilicate and a top layer made of polyacrylic. The coating was applied on the conductor using a continuous reel-to-reel dip coating process and showed very good adherence and flexibility that is suitable for magnet coil winding. The thickness of the coating is a function of slurry viscosity, wire withdrawal speed and wire radius. Small test coils were built with the coated Bi-2212 round-wires and were heat treated at 100 atm pressure. During the heat treatment, the PVB and polyacrylic were removed from the green coating and the polysilicate decomposed to SiO2 that served as a sintering aid for TiO2. After the heat treatment, the coating remained strongly adhered to the conductor and did not have a detrimental effect on the critical current (Ic) values. The breakdown voltage was about 150 V across a 7 μm thick heat treated coating on Bi-22112 round-wire conductor, corresponding to a dc dielectric strength of about 21 MV m-1.

  15. A Brown Mesoporous TiO2-x /MCF Composite with an Extremely High Quantum Yield of Solar Energy Photocatalysis for H2 Evolution.

    Science.gov (United States)

    Xing, Mingyang; Zhang, Jinlong; Qiu, Bocheng; Tian, Baozhu; Anpo, Masakazu; Che, Michel

    2015-04-24

    A brown mesoporous TiO2-x /MCF composite with a high fluorine dopant concentration (8.01 at%) is synthesized by a vacuum activation method. It exhibits an excellent solar absorption and a record-breaking quantum yield (Φ = 46%) and a high photon-hydrogen energy conversion efficiency (η = 34%,) for solar photocatalytic H2 production, which are all higher than that of the black hydrogen-doped TiO2 (Φ = 35%, η = 24%). The MCFs serve to improve the adsorption of F atoms onto the TiO2 /MCF composite surface, which after the formation of oxygen vacancies by vacuum activation, facilitate the abundant substitution of these vacancies with F atoms. The decrease of recombination sites induced by high-concentration F doping and the synergistic effect between lattice Ti(3+)-F and surface Ti(3+)-F are responsible for the enhanced lifetime of electrons, the observed excellent absorption of solar light, and the photocatalytic production of H2 for these catalysts. The as-prepared F-doped composite is an ideal solar light-driven photocatalyst with great potential for applications ranging from the remediation of environmental pollution to the harnessing of solar energy for H2 production.

  16. Fabrication and Characterization of Tailored TiO2and WO3/MWCNT Composites for Methylene Blue Decomposition%Fabrication and Characterization of Tailored TiO2 and WO3/MWCNT Composites for Methylene Blue Decomposition

    Institute of Scientific and Technical Information of China (English)

    ZHU Lei; MENG Zeda; OH Won-Chun

    2011-01-01

    A sol-gel method was used to prepare WO3/MWCNT-TiO2 composites. Their photocatalytic activities were evaluated by the degradation of methylene blue (MB) solution under UV light. The catalysts were characterized by X-ray diffraction, specific surface area measurement, energy-dispersive X-ray analysis, transmission and scanning electron microscopy. Aqueous MB solutions of 100 ml were photode graded by a small amount of the WO3/MWCNT-TiO2 composite under UV light irradiation. The photocatalytic data showed that the WO3/MWCNT-TiO2 composite achieved a high rate of MB photodegradation. This was attributed to the use of MWCNT which can absorb UV light to create photo-induced electrons, strong adsorption of dye molecules on the photocatalyst, and reduced recombination rate of electron-holes in the WO3/MWCNT-TiO2 composite due to the introduction of the WO3 semiconductor.

  17. Synthesis, Characterization and Photocatalytic Activity of TiO2 Film/Bi2O3 Microgrid Heterojunction

    Institute of Scientific and Technical Information of China (English)

    Liugang Wang; Junying Zhang; Chunzhi Li; Hailing Zhu; Wenwen Wang; Tianmin Wang

    2011-01-01

    TiO2 film modified by Bi2O3 microgrid array was successfully fabricated by using a microsphere lithography method. The structure and morphology of TiO2 film, Bi2O3 film and TiO2 film/Bi2O3 microgrid heterojunction were characterized through X-ray diffraction, atomic force microscopy and scanning electron microscopy. The optical transmittance spectra and the photocatalytic degradation capacity of these samples to rhodamine B were determined via ultraviolet-visible spectroscopy. The results indicated that the coupled system showed higher photocatalytic activity than pure TiO2 and Bi2O3 films under xenon lamp irradiation. The enhancement of the photocatalytic activity was ascribed to the special structure, which could improve the separation of photo-generated electrons and holes, enlarge the surface area and extend the response range of TiO2 film from ultraviolet to visible region.

  18. Electrospinning Synthesis and Photocatalytic Activity of Mesoporous TiO2 Nanofibers

    Directory of Open Access Journals (Sweden)

    Jing Li

    2012-01-01

    Full Text Available Titanium dioxide (TiO2 nanofibers in the anatase structure were successfully prepared via electrospinning technique followed by calcination process. The morphologies, crystal structure, surface area, and the photocatalytic activity of resulting TiO2 nanofibers were characterized by field emission scanning electron microscopy (FE-SEM, transmission electron microscopy (TEM, X-ray diffraction (XRD, nitrogen sorption, and UV-vis spectroscopy. The results revealed that calcination temperature had greatly influenced the morphologies of TiO2 nanofibers, but no obvious effect was noticed on the crystal structure of TiO2 nanofibers. The photocatalytic properties of TiO2 nanofibers were evaluated by photocatalytic degradation of rhodamine B (RhB in water under visible light irradiation. It was observed that TiO2 nanofibers obtained by calcination at 500°C for 3 hours exhibited the most excellent photocatalytic activity. We present a novel and simple method to fabricate TiO2 nanofibers with high-photocatalytic activity.

  19. Synthesis and characterization of polythiophene-modified TiO2 nanotube arrays

    Indian Academy of Sciences (India)

    Yuwei Lan; Liya Zhou; Zhangfa Tong; Qi Pang; Fan Wang; Fuzhong Gong

    2011-10-01

    The highly ordered and uniform TiO2 nanotube arrays were fabricated by anodic oxidation method and PTh(polythiophene)/TiO2 nanotube arrays electrode were obtained by electrochemical polymerization. X-ray powder diffraction (XRD) analysis confirmed the formation of TiO2 phase. The morphologies and optical characteristics of the TiO2 nanotube arrays were studied by scanning electron microscope (SEM), UV-Vis absorption spectra and Raman spectra. The results demonstrate that the PTh/TiO2 electrode could enlarge the visible light absorption region and increase the photocurrent in visible region. The modified TiO2 electrode with light-to-electric energy conversion efficiency of 1.46%, the short-circuit current density of 4.52 mAcm-2, open-circuit voltage of 0.74 V and fill factor of 0.44, were obtained.

  20. Anatase TiO(2) nanosheets with exposed (001) facets: improved photoelectric conversion efficiency in dye-sensitized solar cells.

    Science.gov (United States)

    Yu, Jiaguo; Fan, Jiajie; Lv, Kangle

    2010-10-01

    Dye-sensitized solar cells (DSSCs) are fabricated based on anatase TiO(2) nanosheets (TiO(2)-NSs) with exposed {001} facets, which were obtained by a simple one-pot hydrothermal route using HF as a morphology controlling agent and Ti(OC(4)H(9))(4) as precursor. The prepared samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis absorption spectroscopy and N(2) adsorption-desorption isotherms. The photoelectric conversion performances of TiO(2)-NSs solar cells are also compared with TiO(2) nanoparticles (TiO(2)-NPs) and commercial-grade Degussa P25 TiO(2) nanoparticle (P25) solar cells at the same film thickness, and their photoelectric conversion efficiencies (η) are 4.56, 4.24 and 3.64%, respectively. The enhanced performance of the TiO(2)-NS solar cell is due to their good crystallization, high pore volume, large particle size and enhanced light scattering. The prepared TiO(2) nanosheet film electrode should also find wide-ranging potential applications in various fields including photocatalysis, catalysis, electrochemistry, separation, purification and so on.

  1. Anatase TiO2 nanosheets with exposed (001) facets: improved photoelectric conversion efficiency in dye-sensitized solar cells

    Science.gov (United States)

    Yu, Jiaguo; Fan, Jiajie; Lv, Kangle

    2010-10-01

    Dye-sensitized solar cells (DSSCs) are fabricated based on anatase TiO2 nanosheets (TiO2-NSs) with exposed {001} facets, which were obtained by a simple one-pot hydrothermal route using HF as a morphology controlling agent and Ti(OC4H9)4 as precursor. The prepared samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis absorption spectroscopy and N2 adsorption-desorption isotherms. The photoelectric conversion performances of TiO2-NSs solar cells are also compared with TiO2 nanoparticles (TiO2-NPs) and commercial-grade Degussa P25 TiO2 nanoparticle (P25) solar cells at the same film thickness, and their photoelectric conversion efficiencies (η) are 4.56, 4.24 and 3.64%, respectively. The enhanced performance of the TiO2-NS solar cell is due to their good crystallization, high pore volume, large particle size and enhanced light scattering. The prepared TiO2 nanosheet film electrode should also find wide-ranging potential applications in various fields including photocatalysis, catalysis, electrochemistry, separation, purification and so on.

  2. Fabrication of Fe2O3/TiO2 Nanotube Electrode and Its Photoelectrocatalytic Performance in Dye Wastewater Degradation%Fe2O3/TiO2纳米管的制备及其光电催化降解染料废水性能

    Institute of Scientific and Technical Information of China (English)

    丛燕青; 李哲; 张轶; 王齐; 徐谦; 伏芳霞

    2012-01-01

    The FeO3/TiO2 nanotubes electrode was prepared using cathodically electrochemical deposition and anodic oxidation method. The properties of the composite electrode were characterized by scanning electron microscopy, transmission electronic microscope, X-ray diffraction, and UV-Vis diffuse reflectance spectroscopy. The decolorization of methyl orange was investigated using the composite electrode as a photoanode. The results indicated that Fe2O3 nanoparticles were uniformly dispersed on the surface of TiO2 nanotubes electrode. The adsorption edge of the composite electrode exhibited a red shift compared with the pure TiO2 nanotubes electrode. In addition, Fe2O3/TiO2 nanotubes electrode showed higher current density than TiO2 nanotubes electrode under irradiation. It indicated that the metal oxide modification successfully broadened the absorption spectrum of TiO2 nanotubes to the visible light region. Moreover, it was in favor of the separation of photo-induced electron-hole pairs. The Fe2O3/TiO2 nanotubes electrode performed higher photoelectrocatalytic activity for the degradation of methyl orange. Furthermore, it was found that methyl orange had a higher decolorization rate under the acidic condition. When the initial pH value was 3, the decolorization rate of methyl orange solution could reach 91.7% under the light irradiation for 5 min.%采用阴极电沉积和阳极氧化法制备了Fe2O3改性TiO2纳米管(Fe2O3/TiO2-NTs)电极,运用场发射扫描电子显微镜、透射电子显微镜、X射线衍射和紫外-可见漫反射光谱等手段对其进行了表征,考察了其光电化学性能,并研究了复合电极光电催化降解甲基橙染料废水的反应性能.结果表明,Fe2O3的负载成功地将TiO2-NTs的光响应区间拓宽到可见光区域,Fe2O3/TiO2-NTs复合电极的光电流密度达到TiO2-NTs电极的3倍.在光电催化反应中,Fe2O3/TiO2-NTs复合电极对甲基橙的脱色效果明显优于TiO2-NTs电极,以Fe2O3/TiO2-NTs

  3. Fabrication, Modification, and Emerging Applications of TiO2 Nanotube Arrays by Electrochemical Synthesis: A Review

    Directory of Open Access Journals (Sweden)

    Jian-Ying Huang

    2013-01-01

    Full Text Available Titania nanotube arrays (TNAs as a hot nanomaterial have a unique highly ordered array structure and good mechanical and chemical stability, as well as excellent anticorrosion, biocompatible, and photocatalytic performance. It has been fabricated by a facile electrochemical anodization in electrolytes containing small amounts of fluoric ions. In combination with our research work, we review the recent progress of the new research achievements of TNAs on the preparation processes, forming mechanism, and modification. In addition, we will review the potential and significant applications in the photocatalytic degradation of pollutants, solar cells, water splitting, and other aspects. Finally, the existing problems and further prospects of this renascent and rapidly developing field are also briefly addressed and discussed.

  4. Effect of SiN x diffusion barrier thickness on the structural properties and photocatalytic activity of TiO2 films obtained by sol-gel dip coating and reactive magnetron sputtering.

    Science.gov (United States)

    Ghazzal, Mohamed Nawfal; Aubry, Eric; Chaoui, Nouari; Robert, Didier

    2015-01-01

    We investigate the effect of the thickness of the silicon nitride (SiN x ) diffusion barrier on the structural and photocatalytic efficiency of TiO2 films obtained with different processes. We show that the structural and photocatalytic efficiency of TiO2 films produced using soft chemistry (sol-gel) and physical methods (reactive sputtering) are affected differentially by the intercalating SiN x diffusion barrier. Increasing the thickness of the SiN x diffusion barrier induced a gradual decrease of the crystallite size of TiO2 films obtained by the sol-gel process. However, TiO2 obtained using the reactive sputtering method showed no dependence on the thickness of the SiN x barrier diffusion. The SiN x barrier diffusion showed a beneficial effect on the photocatalytic efficiency of TiO2 films regardless of the synthesis method used. The proposed mechanism leading to the improvement in the photocatalytic efficiency of the TiO2 films obtained by each process was discussed.

  5. Fabrication of bidirectionally doped β-Bi2O3/TiO2-NTs with enhanced photocatalysis under visible light irradiation.

    Science.gov (United States)

    Li, Deyi; Zhang, Yonggang; Zhang, Yalei; Zhou, Xuefei; Guo, Sujin

    2013-08-15

    Stable β-Bi2O3/TiO2-NTs photocatalyst with excellent visible-light-activity is successfully prepared by bidirectional doping. Stake structure of the TiO2-NTs provides a larger specific surface area and makes the contact area between the TiO2-NTs and β-Bi2O3 much larger; The stake structure of TiO2-NTs not only leads to a firmer combination of TiO2-NTs and β-Bi2O3, but also makes them dope one another deeply. The modification of Bi species into TiO2-NTs can form Bi-O-Ti chemical absorption bonds, then a localized impurity level is generated within the band gap. Electrons can be excited and transferred from the Bi(3+) impurity level to the conduction band (CB) of TiO2, similar to narrowing the band-gap of TiO2-NTs, resulting in a red shift of the absorption edge and an enhancement in visible-light activity. During annealing, Bi atoms are partially replaced by Ti atoms. The lattice of β-Bi2O3 is compressed around the Ti impurity, making the lattice dislocate and distort. This dislocation and distortion leads to an increase in the β-Bi2O3 valance band (VB), from 2.02 to 2.28 eV. Accordingly, the weak oxidability of β-Bi2O3 is improved, and its photocatalytic ability is further enhanced. Moreover, this lattice dislocation and distortion changes the Bi-O distances, thus remarkably improving the stability of the β-Bi2O3/TiO2-NTs.

  6. Fabrication of hierarchically porous TiO2 nanofibers by microemulsion electrospinning and their application as anode material for lithium-ion batteries.

    Science.gov (United States)

    Zhang, Jin; Cai, Yibing; Hou, Xuebin; Song, Xiaofei; Lv, Pengfei; Zhou, Huimin; Wei, Qufu

    2017-01-01

    Titanium dioxide (TiO2) nanofibers have been widely applied in various fields including photocatalysis, energy storage and solar cells due to the advantages of low cost, high abundance and nontoxicity. However, the low conductivity of ions and bulk electrons hinder its rapid development in lithium-ion batteries (LIB). In order to improve the electrochemical performances of TiO2 nanomaterials as anode for LIB, hierarchically porous TiO2 nanofibers with different tetrabutyl titanate (TBT)/paraffin oil ratios were prepared as anode for LIB via a versatile single-nozzle microemulsion electrospinning (ME-ES) method followed by calcining. The experimental results indicated that TiO2 nanofibers with the higher TBT/paraffin oil ratio demonstrated more axially aligned channels and a larger specific surface area. Furthermore, they presented superior lithium-ion storage properties in terms of specific capacity, rate capability and cycling performance compared with solid TiO2 nanofibers for LIB. The initial discharge and charge capacity of porous TiO2 nanofibers with a TBT/paraffin oil ratio of 2.25 reached up to 634.72 and 390.42 mAh·g(-1), thus resulting in a coulombic efficiency of 61.51%; and the discharge capacity maintained 264.56 mAh·g(-1) after 100 cycles, which was much higher than that of solid TiO2 nanofibers. TiO2 nanofibers with TBT/paraffin oil ratio of 2.25 still obtained a high reversible capacity of 204.53 mAh·g(-1) when current density returned back to 40 mA·g(-1) after 60 cycles at increasing stepwise current density from 40 mA·g(-1) to 800 mA·g(-1). Herein, hierarchically porous TiO2 nanofibers have the potential to be applied as anode for lithium-ion batteries in practical applications.

  7. Fabrication and Magnetic Properties of Co-Doped TiO2 Powders Studied by Nuclear Magnetic Resonance

    Institute of Scientific and Technical Information of China (English)

    GE Shi-Hui; WANG Xin-Wei; KOU Xiao-Ming; ZHOU Xue-Yun; XI Li; ZUO Ya-Lu; YANG Xiao-Lin; ZHAO Yu-Xuan

    2005-01-01

    @@ Co0.04 Ti0.96 O2 powders are fabricated by sol-gel method. The structure and magnetic properties are investigated under different annealing conditions systematically with emphasis on the influence of oxygen pressure. Pure anatase structure was acquired for all the samples annealed at 450 ℃ for one hour. The samples annealed in air exhibit evident room-temperature ferromagnetism (RTFM) with a small magnetic moment of 0.029μB per Co atom and coercivity Hc of 26 Oe, while the samples annealed in vacuum have strong RTFM with a larger magnetic moment of 1.18 μB per Co atom and Hc of 430 Oe. The zero-field spin echo nuclear magnetic resonance spectrum of 59 Co is obtained to prove the existence of Co clusters in the latter samples, implying that the Co clusters are responsible for the strong RTFM in the samples annealed in vacuum. No Co cluster could be observed using both XPS and NMR techniques in the samples annealed in air, implying that the RTFM found in these samples is intrinsic.

  8. Influence of Electrolytes on Photoelectrochemical Properties of TiO_2 Film Electrodes%电解液对TiO_2薄膜电极光电化学性能的影响

    Institute of Scientific and Technical Information of China (English)

    王春涛; 张文魁; 蒋磊; 石德苏

    2011-01-01

    Two kinds of film electrodes,TiO2/ITO and TiO2-xNx/ITO were prepared by depositing TiO2 and TiN on ITO substrates using dc reactive magnetron sputtering and then annealed in an oxidative furnace at 500℃.The crystal structure and chemical composition of the film electrodes were characterized by X-ray diffractometry(XRD) and X-ray photoelectron spectroscopy(XPS).The photoelectrochemical properties of the electrodes were analyzed by testing their LSV and i-t curves under light and in dark,with the two solutions of Na2CO3/NaHCO3(pH=10) and 1M KOH as electrolytes,respectively,for comparation.It shows that the electrolyte of 1M KOH was better for TiO2 and TiO2-xNx photoelectrochemical properties than Na2CO3/NaHCO3(pH=10),and TiO2-xNx/ITO has better photoelectrochemical properties than TiO2/ITO.%本文先用直流磁控溅射法分别在ITO导电玻璃基底上沉积TiO2和TiN二种纳米薄膜,再在500℃的马弗炉氧化性气氛下进行退火处理,制得TiO2/ITO和TiO2-xNx/ITO薄膜电极。样品的结构和成分用XRD和XPS进行表征。然后分别采用pH=10的Na2CO3/NaHCO3缓冲溶液和1M KOH水溶液作为电解液,在三电极体系中用线性扫描伏安法(LSV)和电流时间曲线(i-t)法测定二种薄膜电极在光照和暗态下的光电化学性能。研究结果表明:以1M KOH水溶液作为电解液比pH=10的Na2CO3/NaHCO3缓冲溶液作为电解液更有利于样品发挥其光催化活性;同时,TiO2-xNx/ITO薄膜电极比TiO2/ITO具有更好的光电化学性能。

  9. Enhanced performance of CH3NH3PbI3-x Cl x perovskite solar cells by CH3NH3I modification of TiO2-perovskite layer interface.

    Science.gov (United States)

    Wang, Wen; Zhang, Zongbao; Cai, Yangyang; Chen, Jinshan; Wang, Jianming; Huang, Riyan; Lu, Xubing; Gao, Xingsen; Shui, Lingling; Wu, Sujuan; Liu, Jun-Ming

    2016-12-01

    In this work, perovskite solar cells (PSCs) with CH3NH3PbI3-x Cl x as active layer and spiro-OMeTAD as hole-transport media have been fabricated by one-step method. The methylammonium iodide (CH3NH3I) solution with different concentrations is used to modify the interface between mesoporous TiO2 (meso-TiO2) film and CH3NH3PbI3-x Cl x perovskite layer. Several techniques including X-ray diffraction, scanning electron microscopy, optical absorption, electrochemical impedance spectroscopy (EIS) and photoluminescence are used to investigate the effect of the interfacial modification. It is found that the interfacial modification by CH3NH3I enhance the crystallinity and increase the grain size of CH3NH3PbI3-x Cl x layer, and improve the surface wetting properties of perovskite precursor on meso-TiO2 film. The sunlight absorption and external quantum efficiency of PSCs in the visible region with wavelength less than 600 nm have been improved. The Nyquist plots obtained from the EIS suggest that the CH3NH3I modification can reduce the charge recombination rates. The photoluminescence measurement shows that the exciton dissociation in the modified devices is more effective than that in the control samples. The photovoltaic performance of the modified devices can be significantly improved with respect to the reference (control) devices. The CH3NH3I modified devices at the optimized concentration demonstrate the average power conversion efficiency of 12.27 % in comparison with the average efficiency of 9.68 % for the reference devices.

  10. Enhanced performance of CH3NH3PbI3- x Cl x perovskite solar cells by CH3NH3I modification of TiO2-perovskite layer interface

    Science.gov (United States)

    Wang, Wen; Zhang, Zongbao; Cai, Yangyang; Chen, Jinshan; Wang, Jianming; Huang, Riyan; Lu, Xubing; Gao, Xingsen; Shui, Lingling; Wu, Sujuan; Liu, Jun-Ming

    2016-06-01

    In this work, perovskite solar cells (PSCs) with CH3NH3PbI3- x Cl x as active layer and spiro-OMeTAD as hole-transport media have been fabricated by one-step method. The methylammonium iodide (CH3NH3I) solution with different concentrations is used to modify the interface between mesoporous TiO2 (meso-TiO2) film and CH3NH3PbI3- x Cl x perovskite layer. Several techniques including X-ray diffraction, scanning electron microscopy, optical absorption, electrochemical impedance spectroscopy (EIS) and photoluminescence are used to investigate the effect of the interfacial modification. It is found that the interfacial modification by CH3NH3I enhance the crystallinity and increase the grain size of CH3NH3PbI3- x Cl x layer, and improve the surface wetting properties of perovskite precursor on meso-TiO2 film. The sunlight absorption and external quantum efficiency of PSCs in the visible region with wavelength less than 600 nm have been improved. The Nyquist plots obtained from the EIS suggest that the CH3NH3I modification can reduce the charge recombination rates. The photoluminescence measurement shows that the exciton dissociation in the modified devices is more effective than that in the control samples. The photovoltaic performance of the modified devices can be significantly improved with respect to the reference (control) devices. The CH3NH3I modified devices at the optimized concentration demonstrate the average power conversion efficiency of 12.27 % in comparison with the average efficiency of 9.68 % for the reference devices.

  11. Physical properties of NxTiO2 prepared by sol-gel route

    Science.gov (United States)

    Brahimi, Razika; Bessekhouad, Yassine; Trari, Mohamed

    2012-09-01

    The compounds NxTiO2(x=0, 0.05, 0.1, 0.2) with the anatase structure have been synthesized by Sol-Gel method using Tri-ethyl Amine as nitrogen source and their optical, electrical and electrochemical properties are investigated. The electrical conductivity and thermoelectric power are measured in the temperature rang 300-600 K. The samples exhibit p-type behavior in contrast to TiO2. The doped-samples exhibit two optical transitions (2.35≤Eh-Vis(eV)≤2.55; 1.97≤El-Vis (eV)≤2.06) directly allowed in the visible region, while only one transition is observed in UV region (EUV∼3.00 eV). Pure TiO2 shows direct band gap transition of 3.17 eV. The results confirm experimentally the calculations of Di. Valentin et al. [42]. The transitions Eh-Vis and El-Vis are attributed respectively to the promotion of electrons from the localized N 2p and π* N-O bond to the conduction band. In all cases, EUV is associated to the forbidden band energy. Though that the conductivity is generally improved by doping process, only N0.05TiO2 and N0.1TiO2 shows an enhanced mobility. The mechanism of conduction takes place by small polaron hopping. The band edge positions of NxTiO2 (x=0, 0.05, 0.1, 0.2) at room temperature is predicted from the obtained physical properties. This study proves experimentally the principal role of nitrogen in doping process and permits the electronic states localization associated with N-impurities in TiO2 anatase.

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

    Science.gov (United States)

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

    2013-12-01

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

  13. Electronic ceramics based on polycrystalline SnO2, TiO2 and (Sn xTi1-xO2 solid solution

    Directory of Open Access Journals (Sweden)

    Paulo Roberto Bueno

    2006-09-01

    Full Text Available In the present text we discuss on electronic properties arising from polycrystalline semiconductor ceramics of SnO2, TiO2 and (Sn xTi1-xO2 solid solution rutile-type structure. This is intended to be a short overview of the most recent papers in this area. One of the most important content discussed in this text is based on sinterability of these polycrystalline ceramics, which depends on the target application used to project porous or highly dense microstructure. The majority of discussion is focused in two main applications: varistor and sensor. In both applications there are similarities involved in the control of the sensor and varistor properties, which can mainly ascribed to the grain boundary structure and composition. The similarities found are consistently explained by the fact that all of these n-type semicondutor ceramics have the tendency to establish a grain boundary region with a "p-type semiconductor nature" (due to metal transition atoms segregated at the grain boundary region and then favors negative charged species to adsorb and enrich this region. This configuration enables electrons to become localized on the surfaces, giving rise to a negative surface and, as a result, electron depletion layers are formed, acting as potential barriers which control the properties of the mentioned devices.

  14. Improved Performance of Dye-Sensitized Solar Cells Fabricated from a Coumarin NKX-2700 Dye-Sensitized TiO2/MgO Core-Shell Photoanode with an HfO2 Blocking Layer and a Quasi-Solid-State Electrolyte

    Science.gov (United States)

    Maheswari, D.; Venkatachalam, P.

    2015-03-01

    Dye sensitized solar cells (DSSC) were fabricated from a coumarin NKX-2700 dye-sensitized core-shell photoanode and a quasi-solid-state electrolyte, sandwiched together, with a cobalt sulfide-coated counter electrode. The core-shell photoanode consisted of a composite mixture of 90% TiO2 nanoparticles and 10% TiO2 nanowires (TNPW) as core layer and MgO nanoparticles (MNP) as shell layer. Hafnium oxide (HfO2) was applied to the core-shell photoanode film as a blocking layer. TiO2 nanoparticles, TiO2 nanowires, and TNPW/MNP were characterized by x-ray diffractometry, scanning electron microscopy, and transmission electron microscopy. It was apparent from the UV-visible spectrum of the sensitizing dye coumarin NKX-2700 that its absorption was maximum at 525 nm. Power conversion efficiency (PCE) was greater for DSSC-1, fabricated with a core-shell TNPW/MNP/HfO2 photoanode, than for the other DSSC; its photovoltaic properties were: short circuit photocurrent J sc = 19 mA/cm2, open circuit voltage ( V oc) = 720 mV, fill factor ( FF) = 66%, and PCE ( η) = 9.02%. The charge-transport and charge-recombination behavior of the DSSC were investigated by electrochemical impedance spectroscopy; the results showed that the composite core-shell film resulted in the lowest charge-transfer resistance ( R CE) and the longest electron lifetime ( τ eff). Hence, the improved performance of DSSC-1 could be ascribed to the core-shell photoanode with blocking layer, which increased electron transport and suppressed recombination of charge carriers at the photoanode/dye/electrolyte interface.

  15. Electrospinning preparation of oxygen-deficient nano TiO2-x/carbon fibre membrane as a self-standing high performance anode for Li-ion batteries

    Science.gov (United States)

    Jing, Mao-xiang; Li, Jing-quan; Han, Chong; Yao, Shan-shan; Zhang, Ji; Zhai, Hong-ai; Chen, Li-li; Shen, Xiang-qian; Xiao, Ke-song

    2017-07-01

    Improving the specific capacity and electronic conductivity of TiO2 can boost its practical application as a promising anode material for lithium ion batteries. In this work, a three-dimensional networking oxygen-deficient nano TiO2-x/carbon fibre membrane was achieved by combining the electrospinning process with a hot-press sintering method and directly used as a self-standing anode. With the synergistic effects of three-dimensional conductive networks, surface oxygen deficiency, high specific surface area and high porosity, binder-free and self-standing structure, etc., the nano TiO2-x/carbon fibre membrane electrode displays a high electrochemical reaction kinetics and a high specific capacity. The reversible capacity could be jointly generated from porous carbon, full-lithiation of TiO2 and interfacial lithium storage. At a current density of 100 mA g-1, the reversible discharge capacity can reach 464 mA h g-1. Even at 500 mA g-1, the discharge capacity still remains at 312 mA h g-1. Compared with pure carbon fibre and TiO2 powder, the TiO2-x/C fibre membrane electrode also exhibits an excellent cycle performance with a discharge capacity of 209 mA h g-1 after 700 cycles at the current density of 300 mA g-1, and the coulombic efficiency always remains at approximately 100%.

  16. Highly active mixed-phase TiO2 photocatalysts fabricated at low temperature and the correlation between phase composition and photocatalytic activity

    Institute of Scientific and Technical Information of China (English)

    SHI Lei; WENG Duan

    2008-01-01

    The idea of varying volume ratio of water to ethanol in solvent was firstly employed to yield phase composition controllable mixed-phase titanium dioxide (TiO2) photocatalysts via a low temperature solvothermal route at 353 K. It was found that anatase contentsincrease from 0 to 100% with increase of ethanol contents in solvent. The mixed-phase TiO2 with 60% anatase content exhibited thebest photocatalytic activity in photodecomposing formaldehyde (FAD) under UV light irradiation, which increases by about 270 or400% in comparison with single futile or anatase TiO2, and is slightly better than commercial mixed-phase TiO2 (P25). The synergisticeffect in mixed-phase TiO2 including antenna effect by rutile phase and the activation effect by anatase phase was observed. Further,partially quantitive correlation between phase composition and photocatalytic activity was ascribed to maximizing the synergistic effectand an optimal value of anatase content about 60% in mixed-phase TiO2 photocatalyst was therefore suggested.

  17. Facile route to fabricate carbon-doped TiO2 nanoparticles and its mechanism of enhanced visible light photocatalytic activity

    Science.gov (United States)

    Zhang, Jing; Huang, Gui-Fang; Li, Dongfeng; Zhou, Bing-Xin; Chang, Shengli; Pan, Anlian; Huang, Wei-Qing

    2016-12-01

    High-efficiency photocatalysis requires wide photoresponse range and effective separation of photogenerated charges to fully utilize solar energy. Exploring the simple and cheap methods to synthesize efficient photocatalysts is still a challenging issue. Herein, we report a facile and simple room-temperature hydrolysis method using glucose as carbon source to prepare visible light-active C-doped TiO2 photocatalyst. This approach features low-cost, reliable, and easily upscalable. It is found that C atoms have been incorporated into the interstitial position of anatase TiO2 lattice and distributed homogeneously throughout the surface of TiO2 nanoparticles. The appropriate C doping can greatly improve the separation of photogenerated electron-hole pairs in C-doped TiO2. The C-doped TiO2 samples exhibit enhanced photocatalytic activity with the degradation efficiency under UV and visible light irradiation, which is much faster than that of pure TiO2. The mechanism of the enhanced photocatalytic activity is discussed in detail, which is confirmed by using different scavengers. The work provides a simple and useful way to prepare C-doped wide-gap semiconductors with enhanced photocatalytic activity.

  18. Fabrication of a Porous TiO2-Coated Silica Glass Tube and Its Application for a Handy Water Purification Unit

    Directory of Open Access Journals (Sweden)

    Tsuyoshi Ochiai

    2014-01-01

    Full Text Available A simple, handy, reusable, and inexpensive water purification unit including a one-end sealed porous amorphous-silica (a-silica tube coated with 2 μm of porous TiO2 photocatalyst layers has been developed. Both TiO2 and a-silica layers were formed through outside vapor deposition (OVD. Raman spectrum of the porous TiO2-coated a-silica glass tube indicated that the anatase content of the TiO2 layers of the tube was estimated to be approximately 60 wt%. Developed porous TiO2-coated a-silica glass tube has been assayed for the tube filtering feature against Escherichia coli (E. coli solution used as one of the typical bacteria size species or Qβ phage also used as typical virus size species and compared with the feature of porous a-silica tubes alone. The tubes removed E. coli completely from the aqueous suspension which contained 106 CFU/mL of E. coli without UV irradiation. The porous TiO2-coated a-silica glass tube with UV-C lamps successfully reduced the Qβ phage amount in the suspension from 109 to 103 PFU/mL.

  19. Fabrication of Au@Ag core/shell nanoparticles decorated TiO2 hollow structure for efficient light-harvesting in dye-sensitized solar cells.

    Science.gov (United States)

    Yun, Juyoung; Hwang, Sun Hye; Jang, Jyongsik

    2015-01-28

    Improving the light-harvesting properties of photoanodes is promising way to enhance the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs). We synthesized Au@Ag core/shell nanoparticles decorated TiO2 hollow nanoparticles (Au@Ag/TiO2 HNPs) via sol-gel reaction and chemical deposition. The Au@Ag/TiO2 HNPs exhibited multifunctions from Au@Ag core/shell NPs (Au@Ag CSNPs) and TiO2 hollow nanoparticles (TiO2 HNPs). These Au@Ag CSNPs exhibited strong and broadened localized surface plasmon resonance (LSPR), together with a large specific surface area of 129 m(2) g(-1), light scattering effect, and facile oxidation-reduction reaction of electrolyte from TiO2 HNPs, which resulted in enhancement of the light harvesting. The optimum PCE of η = 9.7% was achieved for the DSSCs using photoanode materials based on TiO2 HNPs containing Au@Ag/TiO2 HNPs (0.2 wt % Au@Ag CSNPs with respect to TiO2 HNPs), which outperformed by 24% enhancement that of conventional photoanodes formed using P25 (η = 7.8%).

  20. Self-doped TiO2-x nanowires with enhanced photocatalytic activity: Facile synthesis and effects of the Ti3+

    Science.gov (United States)

    Wang, Junpeng; Yang, Ping; Huang, Baibiao

    2015-11-01

    Synthesis of Ti3+ self-doped TiO2 with high stability is very necessary to understand the role of Ti3+ defects in photocatalytic process. In this study, we report a simple strategy for preparing stable Ti3+ self-doped TiO2 nanowires with Ti2O3 as precursors. Raman and XPS spectrum confirmed the existence of Ti3+ and oxygen vacancies. Compared with the pure TiO2, the photocatalytic activity of the Ti3+ self-doped TiO2 enhanced under UV light irradiation, however, neither pure TiO2 nor the self-dope TiO2 samples exhibit photocatalytic activity while irradiated under visible light, though the self-doped TiO2 have an enhanced absorption in visible region. On the basis of the experimental results, the possible mechanism of Ti3+ in photocatalytic process is proposed.

  1. Bipolar Resistive Switching Characteristics of HfO2/TiO2/HfO2 Trilayer-Structure RRAM Devices on Pt and TiN-Coated Substrates Fabricated by Atomic Layer Deposition

    Science.gov (United States)

    Zhang, Wei; Kong, Ji-Zhou; Cao, Zheng-Yi; Li, Ai-Dong; Wang, Lai-Guo; Zhu, Lin; Li, Xin; Cao, Yan-Qiang; Wu, Di

    2017-06-01

    The HfO2/TiO2/HfO2 trilayer-structure resistive random access memory (RRAM) devices have been fabricated on Pt- and TiN-coated Si substrates with Pt top electrodes by atomic layer deposition (ALD). The effect of the bottom electrodes of Pt and TiN on the resistive switching properties of trilayer-structure units has been investigated. Both Pt/HfO2/TiO2/HfO2/Pt and Pt/HfO2/TiO2/HfO2/TiN exhibit typical bipolar resistive switching behavior. The dominant conduction mechanisms in low and high resistance states (LRS and HRS) of both memory cells are Ohmic behavior and space-charge-limited current, respectively. It is found that the bottom electrodes of Pt and TiN have great influence on the electroforming polarity preference, ratio of high and low resistance, and dispersion of the operating voltages of trilayer-structure memory cells. Compared to using symmetric Pt top/bottom electrodes, the RRAM cells using asymmetric Pt top/TiN bottom electrodes show smaller negative forming voltage of -3.7 V, relatively narrow distribution of the set/reset voltages and lower ratio of high and low resistances of 102. The electrode-dependent electroforming polarity can be interpreted by considering electrodes' chemical activity with oxygen, the related reactions at anode, and the nonuniform distribution of oxygen vacancy concentration in trilayer-structure of HfO2/TiO2/HfO2 on Pt- and TiN-coated Si. Moreover, for Pt/HfO2/TiO2/HfO2/TiN devices, the TiN electrode as oxygen reservoir plays an important role in reducing forming voltage and improving uniformity of resistive switching parameters.

  2. Fabrication of phase and morphology controlled pure rutile and rutile/anatase TiO2 nanostructures in functional ionic liquid/water

    Science.gov (United States)

    Shahi, Satwant Kaur; Kaur, Navneet; Singh, Vasundhara

    2016-01-01

    In this paper, pure rutile and anatase-rutile TiO2 nanoparticles have been successfully synthesised via a green route by hydrolysis of titanium tetrachloride with room temperature acidic ionic liquid 3-methyl-1-(3-sulfonylpropyl) imidazolium trifluoromethanesulfonate [HO3S(CH2)3MIM][CF3SO3] in aqueous medium. The influence of pH of the solution by varying molar ratio of substrate and ionic liquid has been investigated in both sol⿿gel and hydrothermal synthesis of TiO2 with significant variation in phase, phase composition (ratio of rutile to anatase) and morphology as indicated by various structural analysis such as XRD, TEM, BET, Raman and UV⿿vis absorption spectroscopy. The results indicate formation of a bunch of aligned thin flaky nano-rods of TiO2 which look like nano-flowers with a crystal size of 3⿿5 nm by sol⿿gel method, while in case of hydrothermal method well-defined rutile solid nanorods of TiO2 were formed with variable length in the range of 120⿿170 nm and 20⿿24 nm in width. The photocatalytic activity of the prepared TiO2 samples has been determined by the photodegradation of methyl orange dye (20 ppm) under UV light. Best photocatalytic activity was exhibited by sample S-2 prepared via sol⿿gel method.

  3. Photocatalytic oxidation of gaseous benzene over nanosized TiO2 prepared by solvothermal method

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Nanosized TiO2 particles were prepared by solvothermal method using tetrabutyl titanate as precursor, ethanol and water as solvents, and a facile immobilization method of nanosized TiO2 particles on woven glass fabric was developed. The samples obtained under various preparation conditions were characterized by means of thermo gravimetric analysis (TG) and differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution-transmission electron microscopy (HR-TEM), and Brunauer-Emmett-Teller (BET). The results show that the cube-shape of TiO2 prepared by solvothermal method has good crystallinity of (101) surface, higher thermal stability and large specific surface area. Scanning electron microscopy (SEM) images confirmed that the immobilized TiO2 film was uniformly distributed and clung to the substrate firmly. The photocatalytic activity of the catalysts was tested using photocatalytic oxidation of gaseous benzene. The results show that the TiO2 calcined after solvothermal treatment suffers from lower specific surface area, and hence decreases its photocatalytic activity. The photocatalytic activities of the TiO2 by solvothermal treatment with or without calcination in degradation 400 mg/m3 benzene are 3.7 and 4.1 times as high as catalyst without solvothermal treatment, respectively.

  4. Synthesis of mesoporous TiO(2-x)N(x) spheres by template free homogeneous co-precipitation method and their photo-catalytic activity under visible light illumination.

    Science.gov (United States)

    Parida, K M; Naik, Brundabana

    2009-05-01

    The article presents preparation, characterization and catalytic activity evaluation of an efficient nitrogen doped mesoporous titania sphere photo-catalyst for degradation of methylene blue (MB) and methyl orange (MO) under visible light illumination. Nitrogen doped titania was prepared by soft chemical route i.e. template free, slow and controlled homogeneous co-precipitation from titanium oxysulfate sulfuric acid complex hydrate, urea, ethanol and water. The molar composition of TiOSO(4) to urea was varied to prepare different atomic % nitrogen doped titania. Mesoporous anatase TiO(2-x)N(x) spheres with average crystallite size of 10 nm and formation of titanium oxynitride center were confirmed from HRTEM, XRD and XPS study. UV-vis DRS showed a strong absorption in the range of 400-500 nm which supports its use in visible spectrum of light. Nitrogen adsorption-desorption study supports the porous nature of the doped material. All the TiO(2-x)N(x) samples showed higher photo-catalytic activity than Degussa P(25) and undoped mesoporous titania. Sample containing around one atomic % nitrogen showed highest activity among the TiO(2-x)N(x) samples.

  5. Fabrication of mechanically robust, self-cleaning and optically high-performance hybrid thin films by SiO2&TiO2 double-shelled hollow nanospheres

    Science.gov (United States)

    Yao, Lin; He, Junhui; Geng, Zhi; Ren, Tingting

    2015-07-01

    Low-cost antireflection (AR) thin films on large-area optical surfaces are important for high-performance optical devices, display devices and photovoltaic cells. In the current work, SiO2&TiO2 double-shell hollow nanospheres (DSHNs) were designed, synthesized and utilized as building blocks for fabricating multifunctional AR thin films. By optimizing the porosity of SiO2&TiO2 DSHN and thin film structure, substrates with DSHN thin films attained transmittance as high as 99.4% and average transmittance up to 98.5% in the visible region. The nano-composite SiO2-TiO2 films exhibited intrinsic superhydrophilicity, anti-fogging and high photocatalytic activity. Tape peeling test, sponge washing test, and high temperature and moisture proof test showed favorable robustness and functional durability of the thin films, which make them extremely attractive for applications in lenses, photovoltaic cells and windows of high-rise buildings.Low-cost antireflection (AR) thin films on large-area optical surfaces are important for high-performance optical devices, display devices and photovoltaic cells. In the current work, SiO2&TiO2 double-shell hollow nanospheres (DSHNs) were designed, synthesized and utilized as building blocks for fabricating multifunctional AR thin films. By optimizing the porosity of SiO2&TiO2 DSHN and thin film structure, substrates with DSHN thin films attained transmittance as high as 99.4% and average transmittance up to 98.5% in the visible region. The nano-composite SiO2-TiO2 films exhibited intrinsic superhydrophilicity, anti-fogging and high photocatalytic activity. Tape peeling test, sponge washing test, and high temperature and moisture proof test showed favorable robustness and functional durability of the thin films, which make them extremely attractive for applications in lenses, photovoltaic cells and windows of high-rise buildings. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02467f

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

    Directory of Open Access Journals (Sweden)

    Jiaoping Cai

    2015-02-01

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

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

    Science.gov (United States)

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

    2015-02-01

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

  8. Fabrication of TiO2 nanotubes by anodization and thermal stability of nanotubes%阳极氧化TiO2纳米管的制备及其热稳定性的研究

    Institute of Scientific and Technical Information of China (English)

    吕武龙; 刘宏; 堵国君; 赵越; 张振庭; 任卫红

    2011-01-01

    Objective: To investigate feasibility of fabrication of TiO2 nanotubes by anodization and thermal stability of TiO2 nanotubes.Methods: TiO2 nanotubes were fabricated under the condition of 0.5% HF at 20V for lh via anodization,then TiO2 nanotubes were treated at different temperature.The surface morphologies and crystal structures of samples were examined using SEM and XRD before and after heat treatment.Results: Titanium surface was full of TiO2 nanotubes with tube diameter of 70-100 nm and 300nm in length after anodization.TiO2 nanotubes architecture was still stable at 300℃ and 450℃, partly collapsed at 600℃, and completely collapsed at 700℃.The structure of TiO2 nanotubes changed from amphous to anatase at 300℃ and 450℃ and then to rutile after 600℃.Conclusion: TiO2 nanotube array was successfully prepared by anodization.Heat treatment could change surface morphologies and crystal structures of TiO2 nanotubes.%目的:探讨使用阳极氧化制备TiO2纳米管的可行性以及热处理对TiO2纳米管的影响.方法:在0.5%HF溶液、20V电压的条件下对钛片进行阳极氧化处理1h制备TiO2纳米管,在不同温度下对TiO2纳米管进行热处理,用扫描电镜和X射线衍射仪观察热处理前后的表面形貌和物相成分.结果:钛表面形成了直径为70-100nm、管长为300nm的TiO2纳米管;300℃和450℃热处理的TiO2纳米管结构完整,600℃热处理的TiO2纳米管部分区域发生坍塌;700℃热处理的TiO2纳米管完全坍塌;300℃和450℃热处理的TiO2纳米管由无定形转变为锐钛矿,600℃热处理后TiO2纳米管转变成金红石.结论:阳极氧化法可制备出排列整齐、形貌均一的TiO2纳米管,热处理可改变TiO2纳米管的形貌和物相成分.

  9. 大管径TiO2纳米管的制备及其光解水性能研究∗%Fabrication and photoelectrochemical water splitting performance of large diameter TiO2 nanotube

    Institute of Scientific and Technical Information of China (English)

    李温超; 仲小敏; 杨春艳; 马卫华

    2015-01-01

    Anodization of Ti and the preparation of TiO2 nanotubes with small diameter (20-300 nm)have been reported for many times,however,the fabrication of TiO2 nanotubes with large diameter was still a challenge. In order to fabricate TiO2 nanotube with large diameter,the influence of water content contained in electrolyte on the diameter of TiO2 nanotubes has been investigated in detail.The results show that nanotube diameter in-creases significantly with the increase of water content (from 8% to 12 vol%).However,when the water con-tent increases to 1 3 vol%,the self-ordered nanotubes cannot be obtained by anodization.Further increasing the water content to 20vol%,the compact titanium oxide film can be obtained.Besides,the investigation of voltage affect on the diameter of TiO2 nanotube was carried out in ethylene glycol electrolyte containing 0.3wt% NH4 F and 12vol% H2 O.The results indicate that the largest diameter (about 600 nm)can be obtained at a voltage of 170 V,which has never been reported in the literature.The measurements of photoelectrochemical (PEC)water splitting of the TiO2 nanotubes show that the increase of the nanotubes’diameter was beneficial to their PEC water splitting performance.%采用阳极氧化法制备小管径(20~300 nm)的TiO2纳米管已经有很多报道,但大管径的 TiO2纳米管的制备还是一个挑战.为制备大管径的 TiO2纳米管,研究了高水含量的电解液对纳米管管径的影响.结果表明,纳米管的管径随水含量的增加而增加(8%~12%(体积分数)),而水含量增加到13%(体积分数)时,无法得到规则的纳米管,进一步增加水含量到20%(体积分数),只能得到致密的 TiO2薄膜.此外,在含有0.3%(质量分数)NH4 F 和12%(体积分数)H 2 O 的乙二醇电解液中,研究了不同氧化电压对纳米管管径的影响.结果表明,在170 V 氧化电压下制备的TiO2纳米管的管径可达到600 nm.纳米管的光解水性能测试结果表

  10. Photocatalytic decomposition of N2O over TiO2/g-C3N4 photocatalysts heterojunction

    Science.gov (United States)

    Kočí, K.; Reli, M.; Troppová, I.; Šihor, M.; Kupková, J.; Kustrowski, P.; Praus, P.

    2017-02-01

    TiO2/g-C3N4 photocatalysts with the various TiO2/g-C3N4 weight ratios from 1:2 to 1:6 were fabricated by mechanical mixing in water suspension followed by calcination. Pure TiO2 was prepared by thermal hydrolysis and pure g-C3N4 was prepared from commercial melamine by thermal annealing at 620 °C. All the nanocomposites were characterized by X-ray powder diffraction, UV-vis diffuse reflectance spectroscopy, Raman spectroscopy, infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, photoelectrochemical measurements and nitrogen physisorption. The prepared mixtures along with pure TiO2 and g-C3N4 were tested for the photocatalytic decomposition of nitrous oxide under UVC (λ = 254 nm), UVA (λ = 365 nm) and Vis (λ > 400 nm) irradiation. The TiO2/g-C3N4 nanocomposites showed moderate improvement compared to pure g-C3N4 but pure TiO2 proved to be a better photocatalyst under UVC irradiation. However, under UVA irradiation conditions, the photocatalytic activity of TiO2/g-C3N4 (1:2) nanocomposite exhibited an increase compared to pure TiO2. Nevertheless, further increase of g-C3N4 amount leads/led to a decrease in reactivity. These results are suggesting the nanocomposite with the optimal weight ratio of TiO2 and g-C3N4 have shifted absorption edge energy towards longer wavelengths and decreased the recombination rate of charge carriers compared to pure g-C3N4. This is probably due to the generation of heterojunction on the TiO2/g-C3N4 interface.

  11. ARTICLES: Synthesis and Characterization of TiO2 Doped ZnO Microtubes

    Science.gov (United States)

    Li, Yan

    2010-06-01

    The TiO2-doped ZnO microtubes have been successfully fabricated via a wet chemical method, using zinc chloride and titanium sulphate as the starting materials. The assynthesized products were characterized by X-ray diffraction, field emission scanning electron microscopy and room temperature photoluminescence measurement. The photocatalytic activity in degrading methyl orange was measured with a UV-Vis spectrophotometer. The pure ZnO microtubes exhibit an exact hexangular hollow structure with a diameter of about 700 nm, a length of 3 μm and a wall thickness of about 40 nm. The TiO2-doped ZnO microtubes with TiO2/ZnO ratio less than 5% have the same dimension with the pure ZnO microtubes, a smooth column shape, not a hexangular structure. The growth of ZnO may be inhibited by the more Ti4+ doped into ZnO structure to achieve a small dimension or a multiphase. The crystallinity of ZnO microtubes decreases with increasing TiO2 content, and then a multiphase containing ZnO, Ti3O5 and TiO occur when the TiO2/ZnO ratio is more than 5%. The UV emission intensity of the TiO2-doped ZnO obviously increases and then tends to decrease with TiO2/ZnO ratio increasing. The photocatalytic properties of the TiO2-doped ZnO microtubes are very efficient in degrading organic dyes of methyl orange and are well identical with its PL properties and the crystallinity.

  12. Influence of TiO2 Nanocrystals Fabricating Dye-Sensitized Solar Cell on the Absorption Spectra of N719 Sensitizer

    Directory of Open Access Journals (Sweden)

    Puhong Wen

    2012-01-01

    Full Text Available The absorption spectra of N719 sensitizer anchored on the films prepared by TiO2 nanocrystals with different morphology and size were investigated for improving the performance of dye-sensitized solar cell (DSC. We find that the morphology and size of TiO2 nanocrystals can affect the UV-vis and FT-IR spectra of the sensitizer anchored on their surfaces. In particular, the low-energy metal-to-ligand charge-transfer transitions (MLCT band in the visible absorption spectra of N719 is strongly affected, and locations of these MLCT bands revealed larger differences. The results indicate that there is a red shift of MLCT band in the spectra obtained by using TiO2 nanocrystals with long morphology and large size compared to that in solution. And it produced a larger red-shift on the MLCT band after TiO2 nanocrystals with small size mixed with some long nanocrystals. Accordingly, the utilization rate to visible light is increased. This is a reason why the DSC prepared by using such film as a photoelectrode has better performance than before mixing.

  13. High-performance ethanol gas sensor using TiO2 nanostructures

    Science.gov (United States)

    Priyanka, K. P.; Vattappalam, S. C.; Sankararaman, S.; Balakrishna, K. M.; Varghese, Thomas

    2017-07-01

    TiO2 nanostructures were synthesized by simple chemical routes. As-synthesized nanostructures were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy and selected area diffraction patterns. In the present work, the sensing element was fabricated as thin pellets of TiO2 nanoparticles without using any sensitizers coating. A novel approach of adopting gas sensing measurements of ethanol vapours at a low pressure condition inside a vacuum system has been achieved. All the samples show high sensor response towards ethanol vapour detection at relatively low operating temperatures. Thus, a low-cost industrial production of efficient ethanol gas sensor with good response and recovery time is possible with the synthesized TiO2 nanostructures.

  14. Effectiveness of NiO in replacing Pt in the photochemical generation of hydrogen by (TiO2)1-x(NiO)x/Cd0.8Zn0.2S heterostructures

    Science.gov (United States)

    Roy, Anand; Lingampalli, S. R.; Nassar, Ibrahim M.; Rao, C. N. R.

    2016-10-01

    Hydrogen evolution activity of semiconductor heterostructures of the type (TiO2)1-x(NiO)x/Cd0.8Zn0.2S has been investigated in detail to examine the role of NiO, used in the place of Pt by making use of nanoparticles and nanotubes of TiO2. Combination of NiO and TiO2 markedly changes the photocatalytic efficiency of the heterostructures. While the H2 evolution activity increases smoothly with NiO mole farction up to x~0.50, it increases further reaching a maximum at x~0.83, yielding 1.6 mmol h-1 g-1 (AQY ~2.9%) with Na2S-Na2SO3 as sacrificial agents, under visible-light irradiation, and 6.84 mmol h-1g-1 (AQY ~11.7%) and 13.5 mmol h-1 g-1 (AQY ~10%) with benzyl alcohol-acetic acid as sacrificial agents under visible and UV-visible light irradiation respectively. High hydrogen evolution activity to the tune of three times that yielded by equivalent Pt containg heterostructures has been attained, with a NiO mole fraction of 0.83 in the heterostructures.

  15. One-step preparation and assembly of aqueous colloidal CdS(x)Se(1-x) nanocrystals within mesoporous TiO2 films for quantum dot-sensitized solar cells.

    Science.gov (United States)

    Song, Xiaohui; Wang, Minqiang; Deng, Jianping; Yang, Zhi; Ran, Chenxin; Zhang, Xiangyu; Yao, Xi

    2013-06-12

    In the field of quantum dots (QDs)-sensitized solar cells, semiconductor QDs sensitizer with a moderate band gap is required in order to sufficiently match the solar spectrum and achieve efficient charge separation. At present, changing the size of QDs is the main method used for adjusting their band gap through quantum size effect, however, the pore sizes of mesoporous TiO2 film set a limit on the allowed size of QDs. Therefore, the tuning of electronic and optical properties by changing the particle size could be limited under some circumstances. In this paper, high-quality aqueous CdS(x)Se(1-x) QDs sensitizer is successfully synthesized and effectively deposited on a mesoporous TiO2 film by a one-step hydrothermal method. In addition to size, alloy QDs provide composition as an additional dimension for tailoring their electronic properties. The alloy composition and band gap can be precisely controlled by tuning the precursor (Se/Na2S·9H2O) ratio while maintaining the similar particle size. By using such CdS(x)Se(1-x) sensitized TiO2 films as photoanodes for solar cell, a maximum power conversion efficiency of 2.23% is achieved under one sun illumination (AM 1.5 G, 100 mW cm(-2)).

  16. 3D Ta/TaO x /TiO2/Ti synaptic array and linearity tuning of weight update for hardware neural network applications

    Science.gov (United States)

    Wang, I.-Ting; Chang, Chih-Cheng; Chiu, Li-Wen; Chou, Teyuh; Hou, Tuo-Hung

    2016-09-01

    The implementation of highly anticipated hardware neural networks (HNNs) hinges largely on the successful development of a low-power, high-density, and reliable analog electronic synaptic array. In this study, we demonstrate a two-layer Ta/TaO x /TiO2/Ti cross-point synaptic array that emulates the high-density three-dimensional network architecture of human brains. Excellent uniformity and reproducibility among intralayer and interlayer cells were realized. Moreover, at least 50 analog synaptic weight states could be precisely controlled with minimal drifting during a cycling endurance test of 5000 training pulses at an operating voltage of 3 V. We also propose a new state-independent bipolar-pulse-training scheme to improve the linearity of weight updates. The improved linearity considerably enhances the fault tolerance of HNNs, thus improving the training accuracy.

  17. Thermoelectric Properties of Self Assemble TiO2/SnO2 Nanocomposites

    Science.gov (United States)

    Dynys, Fred; Sayir, Ali; Sehirlioglu, Alp

    2008-01-01

    Recent advances in improving efficiency of thermoelectric materials are linked to nanotechnology. Thermodynamically driven spinodal decomposition was utilized to synthesize bulk nanocomposites. TiO2/SnO2 system exhibits a large spinodal region, ranging from 15 to 85 mole % TiO2. The phase separated microstructures are stable up to 1400 C. Semiconducting TiO2/SnO2 powders were synthesized by solid state reaction between TiO2 and SnO2. High density samples were fabricated by pressureless sintering. Self assemble nanocomposites were achieved by annealing at 1000 to 1350 C. X-ray diffraction reveal phase separation of (Ti(x)Sn(1-x))O2 type phases. The TiO2/SnO2 nanocomposites exhibit n-type behavior; a power factor of 70 (mu)W/m sq K at 1000 C has been achieved with penta-valent doping. Seebeck, thermal conductivity, electrical resistivity and microstructure will be discussed in relation to composition and doping.

  18. Thermoelectric Properties of Self Assembled TiO2/SnO2 Nanocomposites

    Science.gov (United States)

    Dynys, Fred; Sayir, Ali; Sehirlioglu, Alp

    2008-01-01

    Recent advances in improving efficiency of thermoelectric materials are linked to nanotechnology. Thermodynamically driven spinodal decomposition was utilized to synthesize bulk nanocomposites. TiO2/SnO2 system exhibits a large spinodal region, ranging from 15 to 85 mole % TiO2. The phase separated microstructures are stable up to 1400 C. Semiconducting TiO2/SnO2 powders were synthesized by solid state reaction between TiO2 and SnO2. High density samples were fabricated by pressureless sintering. Self assemble nanocomposites were achieved by annealing at 1000 to 1350 C. X-ray diffraction reveal phase separation of (Ti(x)Sn(1-x))O2 type phases. The TiO2/SnO2 nanocomposites exhibit n-type behavior; a power factor of 70 W/mK2 at 1000 C has been achieved with penta-valent doping. Seebeck, thermal conductivity, electrical resistivity and microstructure will be discussed in relation to composition and doping.

  19. 关于丢番图方程(195n)x+(28n)y=(197n)z%On the Diophantine equation (195n)x+(28n)y=(197n)z

    Institute of Scientific and Technical Information of China (English)

    凌灯荣; 翁建欣

    2013-01-01

    In this paper, using the properties of congruences and the order of elements, we show that for any positive integer n, the Diophantine equation (195n)x+(28n)y =(197n)z has no solution other than (x, y, z)=(2, 2, 2) in positive integers.%  运用同余及元素阶的性质,证明了对任意的正整数n,丢番图方程(195n)x+(28n)y=(197n)z仅有正整数解(x, y, z)=(2,2,2)。

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

    Science.gov (United States)

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

    2012-02-15

    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.

  1. 关于方程my(y+1)(y+2)(y+3)=nx(x+1)(x+2)(x+3)%The diophantine equation my(y+1)(y+2)(y+3)=nx(x+1)(x+2)(x+3)

    Institute of Scientific and Technical Information of China (English)

    曹珍富

    2001-01-01

    证明了以下两个定理:1.设m,n是两个互素的正整数,m是完全平方数,n=p2k,p是素数,k是正整数,则题目中的方程无正整数解;2.设p是素数,则方程y(y+1)(y+2)(y+3)=p2nox2n1-1(x+1)2n2-1(x+2)2n3-1(x+3)2n4-1没有正整数解x,y,ni(i=0,1,…,4)。%Let m, n∈N, (m, n)= 1, the author proves that (1) if m is a perfect square, n=p2k, p is a prime, k∈N, then the equation of the title has no positive integer solutions; (2) if p is a prime, then the equationy(y+1)(y+2)(y+3)=p2n0x2n1-1(x+1)2n2-1(x+2)2n3-1(x+3)2n4-1has no positive integersolutions x, y, ni(i=0, 1, …, 4).

  2. Efficient photodegradation of methyl violet dye using TiO2/Pt and TiO2/Pd photocatalysts

    Science.gov (United States)

    Saeed, Khalid; Khan, Idrees; Gul, Tamanna; Sadiq, Mohammad

    2017-02-01

    Titanium oxide supported palladium (TiO2/Pd) and titanium oxide supported platinum (TiO2/Pt) nanoparticles were prepared from their precursors through the incipient wetness method. The TiO2/Pd and TiO2/Pt nanoparticles were characterized by scanning electron microscopy (SEM), and energy dispersive X-rays (EDX), while the photodegradation study of methyl violet was performed by UV/VIS spectrophotometry. The morphological study shows that the Pd and Pt were well deposited on the surface of TiO2, which was confirmed by EDX. Both TiO2/Pd and TiO2/Pt nanoparticles were used as photocatalysts for the photodegradation of methyl violet in aqueous media under UV-light irradiation. The photodegradation study revealed that the TiO2/Pd and TiO2/Pt nanoparticles degraded about 95 and 78% of dye within 20 min, respectively. The effect of various parameters such as catalyst dosage, concentration of dye, and medium on the photocatalytic degradation was examined. The activity of recovered TiO2/Pd and TiO2/Pt nanoparticles was studied.

  3. A facile solvothermal approach of novel Bi2S3/TiO2/RGO composites with excellent visible light degradation activity for methylene blue

    Science.gov (United States)

    Liu, Ya; Shi, Yidan; Liu, Xiang; Li, Hexing

    2017-02-01

    In this paper, novel photocatalyst Bi2S3/TiO2/RGO composites were successfully fabricated by a facile solvothermal method. During this process, TiO2 was coupled with Bi2S3 to generate Bi2S3 sensitized TiO2 nanoparticles, and graphene oxide (GO) was reduced to reduced graphene oxide (RGO), which was uniformly covered with plenty of Bi2S3 and TiO2. The as-prepared samples were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), specific surface areas (BET), X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and photoluminescence (PL) spectroscopy. The results confirmed that Bi2S3 could act as an optical filter, which could be activated under visible light. And the introduction of Bi2S3 could improve the response of TiO2 nanoparticles for visible light. In addition, the Bi2S3/TiO2 in Bi2S3/TiO2/RGO composites had more uniform dispersion on the surface of graphene with less agglomeration in comparison with the Bi2S3/TiO2. Graphene can provide conductive electron channels for separation of the electrons and inhibit the recombination of electrons and holes. Furthermore, the photocatalytic activity of Bi2S3/TiO2/RGO composites was evaluated through the degradation of methylene blue (MB) under visible light irradiation. The Bi2S3/TiO2/RGO composites showed the highest photocatalytic activity among the referred photocatalysts, with about 3-fold increase in photocatalytic efficiency over TiO2 nanoparticles. The mechanism of high photocatalytic activity was also discussed.

  4. 纳米TiO2-ZnO复合材料的制备及其光催化性能%Fabrication and Photocatalytic Properties of TiO2-ZnO Nano-composite Material

    Institute of Scientific and Technical Information of China (English)

    李智卓; 高艳; 陈红征

    2013-01-01

    A novel ZnO@TiO2 nano-composite material is fabricated via sol-gel method by using TiO2 nanotube arrays as the template.The nanostructure of the ZnO@TiO2 nano-composite was observed by SEM.The photocatalytic properties of ZnO@TiO2 nano-composite upon UV light exposure were investigated,which were found to be dependent on the depth and radius of TiO2 nantubes.The photocatalytic activity of the nano-composite was higher than that of ZnO@AAO plus TiO2 template,which could be attributed to the enhancement of charge transfer between TiO2 and ZnO.%本文以TiO2纳米管阵列作为模板,利用溶胶-凝胶法制备ZnO@TiO2纳米复合材料,通过SEM等测试手段对其结构进行了表征,并进一步研究了该复合材料在紫外光下对亚甲基蓝溶液的光催化效率.发现ZnO@TiO2复合材料的光催化效率与模板孔深孔径有关,并且由于TiO2与ZnO间的电荷转移作用,使得纳米复合材料的光催化效率高于TiO2模板和ZnO@AAO光催化效率的线性加合.

  5. TiO2晶型对整理棉织物性能的影响%Effect of different crystals of nano-TiO2 on performances of finished cotton fabric

    Institute of Scientific and Technical Information of China (English)

    戚栋明; 申兴丛; 徐杰; 张睿

    2011-01-01

    将金红石型和锐钛矿型2种不同TiO2的水分散液及其相应的聚丙烯酸丁酯复合胶乳应用于棉织物的功能整理,通过考察紫外线照射下整理织物的老化、杀菌和紫外屏蔽性能,研究整理织物表面不同晶型TiO2对紫外线的响应机制及其对整理织物性能的影响.实验结果表明,2种晶型TiO2均具有较强的紫外屏蔽作用,金红石型TiO2还表现出较强的抗老化作用和较弱的杀菌作用,而锐钛矿型TiO2在提供强杀菌作用的同时反而会显著加速整理棉织物的老化脆损.认为金红石型TiO2对紫外线主要表现为吸收和漫反射作用,锐钛矿型TiO2具有强烈的光催化效应,这种效应产生的大量强氧化性自由基会在杀菌的同时加速纤维分子链的断裂,因此,在进行功能整理时应根据需要选取合适晶型的TiO2,并采取适当措施以抑制其中的不利效应.%Aqueous dispersion of rutile and anatase TiO2 and corresponding poly ( butyl acrylate) composite latexes thereof were used to finish cotton fabrics. The aging resistance, ultraviolet resistance and sterilization properties of the finished cotton fabrics under UV-irradiation were measured in order to investigate the response mechanisms of different crystal TiO2 particles to UV-irradiation and their effects on the performances of finished cotton fabrics. It was found that both of the crystals have good ultraviolet resistance, however, rutile TiO2 finished cotton fabric exhibits outstanding aging resistance but weak sterilization properties because of its absorption and diffuse scattering of UV light, while anatase TiO2 finished cotton fabric offers excellent sterilization but accelerates the aging process due to its strong photocatalytic effect which induces many strong oxidizing free radicals under UV-irradiation, that effectively inactivate bacteria and simultaneously accelerate the breakdown of the molecular chain of fibers. Thus, it is required to select the

  6. Fabrication and Photovoltaic Properties of Ag/Au Modified TiO2 Nanotube Arrays%银金修饰TiO2纳米管阵列光阳极的制备及其光伏性质

    Institute of Scientific and Technical Information of China (English)

    樊莉红; 陈福义; 刘婧; 张金生; 刘建

    2012-01-01

    TiO2 nanotube arrays for dye - sensitized nanocryslal solar cell ( DSSC) photoanode were fabricated by the anodization from titanium foil and modified with Ag and Au on its surface using eleclrodeposi-tion, photodeposition and vacuum sputtering, respectively in this paper. The scanning electron microscope (SEM) images and X -ray diffraction (XRD) patterns show that TiO2 nanotube arrays have regular and orderly structure and are covered by a close nanopaticle film of silver and gold. In contract to pure TiO2 nanotube arrays, the TiO2 array modified with Ag has higher short circuit current density and larger open circuit voltage, which can be enhanced 3.9 and 0.7 times larger than the former, and its electrochemical impedance is reduced significantly as observed from electrochemical impedance spectroscopy (EIS) patterns and photocurrent density - voltage ( J - V ) curves. It shows that Ag modification improves the connectivity among TiO2 nanotubes, assists electron transfer inside the TiO2 nanotubes, and excites pholoelec-tron by surface plasmon resonance,meanwhile promotes the electron - hole separation inside the TiO2 crystals in visible wavelength range through interaction with TiO2.%采用阳极氧化法,以金属钛箔为原料制备了TiO2纳米管阵结构染料敏化纳米晶太阳能电池( DSSC)光阳极,并用电沉积、光沉积和真空蒸发法对其表面分别进行金属Ag和Au修饰.对金属修饰前后的光阳极用扫描电子显微镜(SEM)和X射线衍射分析仪(XRD)表征发现:阳极氧化法制备的TiO2纳米管阵列结构规整有序;经过化学沉积后,其表面均覆盖有一层致密的金属粒子薄膜.测量光电流密度-电压(J-V)曲线和电化学阻抗谱(EIS)发现:相比纯TiO2纳米管阵列,经过Ag修饰后的TiO2阵列其短路电流密度和开路电压最大可以分别提高到前者的4.9和1.7倍,并且其电化学阻抗出现显著降低.研究表明:金属Ag修饰改善了TiO2纳米管之

  7. Comparison of field portable measurements of ultrafine TiO2: X-ray fluorescence, laser-induced breakdown spectroscopy, and Fourier-transform infrared spectroscopy.

    Science.gov (United States)

    LeBouf, Ryan F; Miller, Arthur L; Stipe, Christopher; Brown, Jonathan; Murphy, Nate; Stefaniak, Aleksandr B

    2013-06-01

    Laboratory measurements of ultrafine titanium dioxide (TiO2) particulate matter loaded on filters were made using three field portable methods (X-ray fluorescence (XRF), laser-induced breakdown spectroscopy (LIBS), and Fourier-transform infrared (FTIR) spectroscopy) to assess their potential for determining end-of-shift exposure. Ultrafine TiO2 particles were aerosolized and collected onto 37 mm polycarbonate track-etched (PCTE) filters in the range of 3 to 578 μg titanium (Ti). Limit of detection (LOD), limit of quantification (LOQ), and calibration fit were determined for each measurement method. The LOD's were 11.8, 0.032, and 108 μg Ti per filter, for XRF, LIBS, and FTIR, respectively and the LOQ's were 39.2, 0.11, and 361 μg Ti per filter, respectively. The XRF calibration curve was linear over the widest dynamic range, up to the maximum loading tested (578 μg Ti per filter). LIBS was more sensitive but, due to the sample preparation method, the highest loaded filter measurable was 252 μg Ti per filter. XRF and LIBS had good predictability measured by regressing the predicted mass to the gravimetric mass on the filter. XRF and LIBS produced overestimations of 4% and 2%, respectively, with coefficients of determination (R(2)) of 0.995 and 0.998. FTIR measurements were less dependable due to interference from the PCTE filter media and overestimated mass by 2% with an R(2) of 0.831.

  8. Photocurrent enhanced dye-sensitized solar cells based on TiO2 loaded K6SiW11O39Co(II)(H2O)·xH2O photoanode materials.

    Science.gov (United States)

    Li, Liang; Yang, YuLin; Fan, RuiQing; Wang, Xin; Zhang, Qingming; Zhang, Lingyun; Yang, Bin; Cao, Wenwu; Zhang, Wenzhi; Wang, Yazhen; Ma, Liqun

    2014-01-28

    Through loading of TiO2 on the surface of K6SiW11O39Co(II)(H2O)·xH2O (SiW11Co), a novel photoanode material has been created for dye-sensitized solar cells (DSSC). The absorbing band as well as photoelectricity response range of TiO2@SiW11Co is extended to the visible range. In addition, the absorption in the UV range is enhanced notably compared with P25 (raw TiO2). More importantly, the recombination of the TiO2 network is avoided. TiO2@SiW11Co is mixed with P25 powder (wt ∼1 : 1) to assemble dye-sensitized (N719) solar cells, which exhibit a short-circuit photocurrent density as high as 18.05 mA cm(-2), which is 64% higher than blank samples under the standard AM1.5G global solar irradiation. In addition, the mechanisms for SiW11Co in DSSC are proposed.

  9. Hydrothermal fabrication of quasi-one-dimensional single-crystalline anatase TiO2 nanostructures on FTO glass and their applications in dye-sensitized solar cells.

    Science.gov (United States)

    Liao, Jin-Yun; Lei, Bing-Xin; Wang, Yu-Fen; Liu, Jun-Min; Su, Cheng-Yong; Kuang, Dai-Bin

    2011-01-24

    One-dimensional and quasi-one-dimensional semiconductor nanostructures are desirable for dye-sensitized solar cells (DSSCs), since they can provide direct pathways for the rapid collection of photogenerated electrons, which could improve the photovoltaic performance of the device. Quasi-1D single-crystalline anatase TiO(2) nanostructures have been successfully prepared on transparent, conductive fluorine-doped tin oxide (FTO) glass with a growth direction of [101] through a facile hydrothermal approach. The influences of the initial titanium n-butoxide (TBT) concentration, hydrothermal reaction temperature, and time on the length of quasi-1D anatase TiO(2) nanostructures and on the photovoltaic performance of DSSCs have been investigated in detail. A power conversion efficiency of 5.81% has been obtained based on the prepared TiO(2) nanostructure photoelectrode 6.7 μm thick and commercial N719 dye, with a short-circuit current density of 13.3 mA cm(-2) , an open-circuit voltage of 810 mV, and a fill factor of 0.54. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Fabrication of Ce/N co-doped TiO2/diatomite granule catalyst and its improved visible-light-driven photoactivity.

    Science.gov (United States)

    Chen, Yan; Liu, Kuiren

    2017-02-15

    Eliminating antibiotic remnants in aquatic environment has become one of the hottest topics among current research works. Thus, we prepared Ce, N co-doped TiO2/diatomite granule (CNTD-G) catalyst to provide a new method. As one typical antibiotics, oxytetracycline (OTC) was selected as the target pollutant to be degradated under visible light irradiation. The carrier diatomite helped the spread of TiO2 nanoparticles onto its surface, and inhibited their agglomeration. The synergy of Ce and N dopants highly improved the visible-light-driven photoactivity of TiO2. The optimal doping amount and degradation conditions were determined. Besides, the effects of impurity ions were also investigated, including cations: Ca(2+), Mg(2+); or anions: NO3(-), SO4(2-) and PO4(3-). The intermediates generated during degradation process were studied, and the mechanism of the photodegradation process was proposed. CNTD-G could be easily collected from the reactor, and showed excellent recyclability. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Origin of the large positive magnetoresistance of G e1 -xM nx granular thin films

    Science.gov (United States)

    Wakabayashi, Yuki K.; Akiyama, Ryota; Takeda, Yukiharu; Horio, Masafumi; Shibata, Goro; Sakamoto, Shoya; Ban, Yoshisuke; Saitoh, Yuji; Yamagami, Hiroshi; Fujimori, Atsushi; Tanaka, Masaaki; Ohya, Shinobu

    2017-01-01

    G e1 -xM nx (GeMn) granular thin films are a unique and promising material for spintronic applications owing to their large positive magnetoresistance (MR). Previous studies of GeMn have suggested that the large MR is related to the nanospinodal decomposition of GeMn into Mn-rich ferromagnetic nanoparticles and a Mn-poor paramagnetic matrix. However, the microscopic origin of the MR has not yet been clarified. Here, we develop a method to separately investigate the magnetic properties of the nanoparticles and the matrix, utilizing the extremely high sensitivity of x-ray magnetic circular dichroism (XMCD) to the local magnetic state of each atom. We find that the MR ratio is proportional to the product of the magnetizations originating from the nanoparticles and the matrix. This result indicates that the spin-polarized holes in the nanoparticles penetrate into the matrix and that these holes undergo first order magnetic scattering by the paramagnetic Mn atoms in the matrix, which induces the large MR.

  12. Enhanced visible-light-driven photocatalytic activity of mesoporous TiO(2-x)N(x) derived from the ethylenediamine-based complex.

    Science.gov (United States)

    Jiang, Zheng; Kong, Liang; Alenazey, Feraih Sh; Qian, Yangdong; France, Liam; Xiao, Tiancun; Edwards, Peter P

    2013-06-21

    A facile solvent evaporation induced self-assembly (SEISA) strategy was developed to synthesize mesoporous N-doped anatase TiO2 (SE-meso-TON) using a single organic complex precursor derived in situ from titanium butoxide and ethylenediamine in ethanol solution. After the evaporation of ethanol in a fume hood and subsequent calcinations at 450 °C, the obtained N-doped TiO2 (meso-TON) anatase was of finite crystallite size, developed porosity, large surface area (101 m(2) g(-1)) and extended light absorption in the visible region. This SE-meso-TON also showed superior photocatalytic activity to the SG-meso-TON anatase prepared via sol-gel synthesis. On the basis of characterization results from XRD, XPS, N2 adsorption-desorption and ESR, the enhanced visible-light-responsive photocatalytic activity of SE-meso-TON was assigned to its developed mesoporosity and reduced oxygen vacancies.

  13. Pulsed Laser Ablation-Induced Green Synthesis of TiO2 Nanoparticles and Application of Novel Small Angle X-Ray Scattering Technique for Nanoparticle Size and Size Distribution Analysis

    Science.gov (United States)

    Singh, Amandeep; Vihinen, Jorma; Frankberg, Erkka; Hyvärinen, Leo; Honkanen, Mari; Levänen, Erkki

    2016-10-01

    This paper aims to introduce small angle X-ray scattering (SAXS) as a promising technique for measuring size and size distribution of TiO2 nanoparticles. In this manuscript, pulsed laser ablation in liquids (PLAL) has been demonstrated as a quick and simple technique for synthesizing TiO2 nanoparticles directly into deionized water as a suspension from titanium targets. Spherical TiO2 nanoparticles with diameters in the range 4-35 nm were observed with transmission electron microscopy (TEM). X-ray diffraction (XRD) showed highly crystalline nanoparticles that comprised of two main photoactive phases of TiO2: anatase and rutile. However, presence of minor amounts of brookite was also reported. The traditional methods for nanoparticle size and size distribution analysis such as electron microscopy-based methods are time-consuming. In this study, we have proposed and validated SAXS as a promising method for characterization of laser-ablated TiO2 nanoparticles for their size and size distribution by comparing SAXS- and TEM-measured nanoparticle size and size distribution. SAXS- and TEM-measured size distributions closely followed each other for each sample, and size distributions in both showed maxima at the same nanoparticle size. The SAXS-measured nanoparticle diameters were slightly larger than the respective diameters measured by TEM. This was because SAXS measures an agglomerate consisting of several particles as one big particle which slightly increased the mean diameter. TEM- and SAXS-measured mean diameters when plotted together showed similar trend in the variation in the size as the laser power was changed which along with extremely similar size distributions for TEM and SAXS validated the application of SAXS for size distribution measurement of the synthesized TiO2 nanoparticles.

  14. Pulsed Laser Ablation-Induced Green Synthesis of TiO2 Nanoparticles and Application of Novel Small Angle X-Ray Scattering Technique for Nanoparticle Size and Size Distribution Analysis.

    Science.gov (United States)

    Singh, Amandeep; Vihinen, Jorma; Frankberg, Erkka; Hyvärinen, Leo; Honkanen, Mari; Levänen, Erkki

    2016-12-01

    This paper aims to introduce small angle X-ray scattering (SAXS) as a promising technique for measuring size and size distribution of TiO2 nanoparticles. In this manuscript, pulsed laser ablation in liquids (PLAL) has been demonstrated as a quick and simple technique for synthesizing TiO2 nanoparticles directly into deionized water as a suspension from titanium targets. Spherical TiO2 nanoparticles with diameters in the range 4-35 nm were observed with transmission electron microscopy (TEM). X-ray diffraction (XRD) showed highly crystalline nanoparticles that comprised of two main photoactive phases of TiO2: anatase and rutile. However, presence of minor amounts of brookite was also reported. The traditional methods for nanoparticle size and size distribution analysis such as electron microscopy-based methods are time-consuming. In this study, we have proposed and validated SAXS as a promising method for characterization of laser-ablated TiO2 nanoparticles for their size and size distribution by comparing SAXS- and TEM-measured nanoparticle size and size distribution. SAXS- and TEM-measured size distributions closely followed each other for each sample, and size distributions in both showed maxima at the same nanoparticle size. The SAXS-measured nanoparticle diameters were slightly larger than the respective diameters measured by TEM. This was because SAXS measures an agglomerate consisting of several particles as one big particle which slightly increased the mean diameter. TEM- and SAXS-measured mean diameters when plotted together showed similar trend in the variation in the size as the laser power was changed which along with extremely similar size distributions for TEM and SAXS validated the application of SAXS for size distribution measurement of the synthesized TiO2 nanoparticles.

  15. Anatase TiO2 sheet-assisted synthesis of Ti(3+) self-doped mixed phase TiO2 sheet with superior visible-light photocatalytic performance: Roles of anatase TiO2 sheet.

    Science.gov (United States)

    Zhang, Xiaojie; Zuo, Guoqing; Lu, Xin; Tang, Changqing; Cao, Shuo; Yu, Miao

    2017-03-15

    On the basis of measurements, such as field emission scanning electron microscope, UV-Vis diffuse reflectance spectra, X-ray diffraction, electron paramagnetic resonance, photoluminescence spectra, and photocurrent measurements, the roles of anatase TiO2 sheet on synthesizing Ti(3+) self-doped mixed phase TiO2 nanosheets (doped TiO2 (A/R, TiO2 (A))) and on improving the performance for photocatalytic CO2 reduction were explored systematically. High surface area anatase TiO2 nanosheets (TiO2 (A)) as a substrate, structure directing agent, and inhibitor, mediated the synthesis of Ti(3+) self-doped mixed phase TiO2 nanosheets. Addition of TiO2 (A) significantly improved not only visible light absorption of doped TiO2 (A/R, TiO2 (A)), but also the efficiency of photo-excited charges separations due to the existence of interfacial regions of anatase-rutile TiO2 junctions. Finally, a possible mechanism for interfacial charge transfer at the anatase-rutile TiO2 interface and for photocatalytic CO2 reduction over Pt loaded doped TiO2 (A/R, TiO2 (A)) were proposed.

  16. TiO2纳米片/巢状分级结构纳米阵列薄膜的制备及其在染料敏化太阳能电池中的应用%Fabrication of Nanosheet/Nestlike Nanoarray Hierarchical TiO2 Film for Dye-Sensitized Solar Cell

    Institute of Scientific and Technical Information of China (English)

    常萌蕾; 李新军

    2012-01-01

    A hierarchical configuration of TiO2 nanoarray film,comprising a nestlike TiO2 nanoarray layer integrated with a nanosheet network overlayer,was constructed.The hierarchical TiO2 film was obtained by the post-hydrothermal treatment with NaOH solution on hydrothermally synthesized TiO2-derived nanostructured arrays grown on fluorine-doped tin oxide substrate (FTO).The TiO2 films were characterized by field-emission scanning electron microscope (FE-SEM),X-ray diffraction (XRD),ultraviolet-visible (UV-Vis) diffuse reflectance spectroscopy,and absorbance spectroscopy.FE-SEM shows that the hierarchical TiO2 film with a thickness of 1.5 μm is composed of a nanosheet overlayer (~0.2 μm height) and the nestlike nanoarray layer (~1.3 μm height).XRD patterns display that the TiO2 films have pure anatase phase structure.UV-Vis spectra reveal enhanced light scattering and dye adsorption ability of the hierarchical TiO2 film.For the dye-sensitized solar cell (DSSC) based on the nanosheet/nestlike nanoarray hierarchical TiO2 film,a short-circuit current (Jac) of 7.79 mA· cm-2,open-circuit voltage (Voc) of 0.80 V,fill factor (FF) of 0.40,and photoelectric conversion efficiency (η) of 2.48% are achieved.Within the dye-sensitized solar cell,the photoelectric conversion efficiency of the hierarchical TiO2 film was nearky ten times higher than that of nanostructured array film.%采用水热合成法在氟掺杂二氧化锡(FTO)导电玻璃基底上得到TiO2纳米阵列薄膜,并进一步通过NaOH溶液水热处理制备了由巢状纳米阵列及纳米片覆盖层构成的TiO2纳米阵列分级结构一体化薄膜.采用场发射扫描电镜(FE-SEM),X射线衍射(XRD),紫外-可见(UV-Vis)漫反射光谱和吸收光谱技术对TiO2薄膜的结构和性质进行表征.FE-SEM结果表明:分级结构TiO2薄膜膜厚为1.5 μm,薄膜由一层纳米片覆盖层(约0.2 μm高)和一层巢状纳米阵列层(约1.3 μm高)组成.XRD谱图表明TiO2薄膜为锐钛矿相.UV-Vis

  17. Co-Pi和Cu2O共修饰TiO2薄膜及其光电化学性质研究%Fabrication and Photoelectrochemical Properties of Co-Pi and Cu2O Co-decorated TiO2 films

    Institute of Scientific and Technical Information of China (English)

    姜春香; 沈明荣

    2014-01-01

    用阳极氧化法在Ti基片上制备出TiO2薄膜,然后通过电化学沉积法将Co-Pi和Cu2O沉积在TiO2薄膜表面。通过扫描电镜、X-射线衍射和光电化学性质测试,发现TiO2薄膜表面先沉积Co-Pi能够有效阻止Cu2O颗粒堆积,光电流显著提高。而先沉积Cu2O后沉积Co-Pi,则会使Cu2O还原为Cu,同时形貌发生改变。特别地,沉积300秒Co-Pi后再沉积Cu2O颗粒,能得到200 mA/cm2的最大光电流。%TiO2 film is prepared on Ti substrates by anodic oxidation method. Then Co-Pi and Cu2O particles are fabricated on TiO2 flat surface using a facial electrochemical deposition method. Scanning electron microsco-py, X-ray diffraction and photoelectrochemical properties reflect that depositing Co-Pi particles in advance on the surface of TiO2 thin films can prevent Cu2O forming stacked particle structure, increase the photocurrent sig-nificantly, and deposit Co-Pi after Cu2O makes Cu2O reduction to Cu and that at the same time the morphology changes a lot. Specifically, when the deposition time of Co-Pi is set to be 300 s, the structure of TiO2/Co-Pi/Cu2O can get the maximum photocurrent of 200 A cm-2 .

  18. A Final Result on the Oscillation of Solutions of the Linear Discrete Delayed Equation Δx(n=−p(nx(n−k with a Positive Coefficient

    Directory of Open Access Journals (Sweden)

    J. Baštinec

    2011-01-01

    Full Text Available A linear (k+1th-order discrete delayed equation Δx(n=−p(nx(n−k where p(n a positive sequence is considered for n→∞. This equation is known to have a positive solution if the sequence p(n satisfies an inequality. Our aim is to show that, in the case of the opposite inequality for p(n, all solutions of the equation considered are oscillating for n→∞.

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

    Science.gov (United States)

    Ghalamboran, Milad; Saedi, Yasin

    2016-03-01

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

  20. Facile preparation of N-doped TiO2 at ambient temperature and pressure under UV light with 4-nitrophenol as the nitrogen source and its photocatalytic activities.

    Science.gov (United States)

    Horikoshi, Satoshi; Shirasaka, Yutaro; Uchida, Hiroshi; Horikoshi, Natsuko; Serpone, Nick

    2016-08-04

    To date syntheses of nitrogen-doped TiO2 photocatalysts (TiO2-xNx) have been carried out under high temperatures and high pressures with either NH3 or urea as the nitrogen sources. This article reports for the first time the facile preparation of N-doped TiO2 (P25 titania) in aqueous media at ambient temperature and pressure under inert conditions (Ar- and N2-purged dispersions) with 4-nitrophenol (or 4-nitrobenzaldehyde) as the nitrogen source. The resulting N-doped P25 TiO2 materials were characterized by UV/Vis and X-ray photoelectron spectroscopies (XPS) that confirmed the presence of nitrogen within the photocatalyst; X-ray diffraction (XRD) techniques confirmed the crystalline phases of the doped material. The photocatalytic activity of N-doped TiO2 was assessed through examining the photodegradation of 4-chlorophenol in aqueous media and iso-propanol as a volatile pollutant under UV/Vis and visible-light irradiation. Under visible light irradiation, undoped P25 was inactive contrary to N-doped P25 that successfully degraded 95% of the 4-chlorophenol (after 10 h) and 23% of iso-propanol (after 2.5 h).

  1. TiO2纳米管阵列的制备及光电性能研究%Fabrication and Photoelectric Properties Research of TiO2 Nanotube Arrays

    Institute of Scientific and Technical Information of China (English)

    李娜; 林仕伟; 赵玉伟

    2013-01-01

      用阳极氧化法制备出高度致密、有序的TiO2纳米管阵列。利用SEM和XRD表征分析纳米管阵列的形貌和结构,并通过电化学瞬时光电流对TiO2纳米管阵列的光电化学特性进行了研究。实验结果表明:经过500℃退火后的TiO2为掺杂有金红石相的锐钛矿的混晶结构。随着退火温度升高到600℃,金红石型的晶相比例增加。光电测试结果表明:随着退火温度升高,瞬时光电流减小,同时阳极氧化时间影响TiO2纳米管阵列光电极的光电性能。%TiO2 nanotube arrays were fabricated by anodic oxidation on a titanium sheet. The morphology and structure of the nanotube arrays were characterized by SEM and XRD. The photoelectric properties of the nanotube arrays electrodes were evaluated by transient photocurrents. The results show that the structure of nanotube arrays is a mixture phase of anatase and rutile annealed at 500℃. With the annealing temperature increasing to 600℃, the phase ratio of rutile increases. Photoelectric test results show that: the instantaneous photoelectric current decreases as the annealing temperature increases and at the same time, anodic oxidation time affects the photoelectric properties of nanotube arrays photoelectrode.

  2. Fabrication of TiO2-Bi2WO6 Binanosheet for Enhanced Solar Photocatalytic Disinfection of E. coli: Insights on the Mechanism.

    Science.gov (United States)

    Jia, Yanan; Zhan, Sihui; Ma, Shuanglong; Zhou, Qixing

    2016-03-23

    TiO2-Bi2WO6 binanosheet (TBWO), synthesized by a facile two-step hydrothermal method, was used as an effective visible-light-driven photocatalyst for the inactivation of E. coli and was characterized by TEM, SEM, XRD, FTIR, XPS, and BET. A series of TBWOs with different doping ratios of TiO2 loading from 10 to 55 wt % were synthesized. Among all of the TBWOs, 40% TBWO exhibited the best bacteria disinfection efficiency, and the quantity of viable bacteria could reach 10° with 40% TBWO (100 μg/mL) after being illuminated for 4 h. Furthermore, the confocal fluorescent-based cell live/dead test and the SEM technology were applied to verify the photocatalytically lethal effect toward E. coli and the rupture of bacterial membranes. The leak of bacterial contents, including the bacterial genome represented by relevant 16srDNA, and total protein were detected by PCR and bicinchoninic acid assay. In this work, the antibacterial mechanism was studied by employing photoelectrochemical techniques, electron spin resonance (ESR), and scavengers of different reactive species, revealing the pivotal roles of electron hole (h(+)) and electron (e(-)) in the photocatalytic process. In addition, the •O2(-) and •OH radicals were also detected in the TBWOs system by ESR. It was found that the adsorption of visible light and separation of photogenerated carriers within TiO2 have been largely promoted after being coupled with Bi2WO6, which should be responsible for the improved bactericidal effect.

  3. X-ray Spectroscopy of Ultra-thin Oxide/oxide Heteroepitaxial Films: A Case Study of Single-nanometer VO2/TiO2

    Energy Technology Data Exchange (ETDEWEB)

    Quackenbush, Nicholas F. [Binghamton Univ., NY (United States); Paik, Hanjong [Cornell Univ., Ithaca, NY (United States); Woicik, Joseph C. [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Arena, Dario A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Schlom, Darrell G. [Cornell Univ. and Kavli Inst. at Cornell for Nanoscale Science, Ithaca, NY (United States); Piper, Louis F. J. [Binghamton Univ., NY (United States)

    2015-08-21

    Epitaxial ultra-thin oxide films can support large percent level strains well beyond their bulk counterparts, thereby enabling strain-engineering in oxides that can tailor various phenomena. At these reduced dimensions (typically < 10 nm), contributions from the substrate can dwarf the signal from the epilayer, making it difficult to distinguish the properties of the epilayer from the bulk. This is especially true for oxide on oxide systems. Here, we have employed a combination of hard X-ray photoelectron spectroscopy (HAXPES) and angular soft X-ray absorption spectroscopy (XAS) to study epitaxial VO2/TiO2 (100) films ranging from 7.5 to 1 nm. We observe a low-temperature (300 K) insulating phase with evidence of vanadium-vanadium (V-V) dimers and a high-temperature (400 K) metallic phase absent of V-V dimers irrespective of film thickness. Results confirm that the metal insulator transition can exist at atomic dimensions and that biaxial strain can still be used to control the temperature of its transition when the interfaces are atomically sharp. Generally, our case study highlights the benefits of using non-destructive XAS and HAXPES to extract out information regarding the interfacial quality of the epilayers and spectroscopic signatures associated with exotic phenomena at these dimensions.

  4. Fabrication of doped Titania (TiO2) nanofibers to serve as catalysts in NH3-Selective CatalyticReduction (SCR)

    DEFF Research Database (Denmark)

    Marani, Debora; Silva, Rafael Hubert; Dankeaw, Apiwat

    2016-01-01

    of the NOx in exhausts via the NH3 SelectiveCatalytic Reduction (SCR) method. By combining electrospinning and sol-gel chemistry, materials areprocessed as nanofibers with the catalytic components (e. g. V2O5-WO3) incorporated as dopants into thesupporting anatase phase (e. g TiO2). Remarkable high NOx...... conversion efficiencies are obtained andassociated with the unique features deriving from the synergism among the doping approach, the nanoscaleconfinement, and the nano-fibrous texture. A novel concept of self-supported, lightweight and ultra-compactdesign SCR reactor is defined....

  5. Hydrogen generation by photoelectrochemical effect of the Cu-doped TiO2 photoanode

    Science.gov (United States)

    Ly, Ngoc Tai; Hoa Dao, Thi; Hoang To, Le Hong; Vu, Dinh Lam; Le, Van Hong

    2014-09-01

    TiO2 film photoanodes with a size of 1 × 1 cm2 were fabricated by a spin coating method. Cu-doped TiO2 powder with various Cu concentrations (0.2, 0.4, 0.6 and 0.8 at%) and surfactant were used as starting materials in coating Cu-doped TiO2 thin films onto FTO/glass substrate. Crystalline structure of TiO2 material, microstructure of the photoanode films and their thickness were identified by x-ray diffraction and Raman scattering. Hydrogen generation from water by photoelectrochemical effect in the visible light was observed by recording I/V characteristics of the photoanode in dark and light regimes. The obtained results have shown that the hydrogen generation efficiency of photoanode nonlinearly depends on Cu concentration. The nonlinear dependence of the hydrogen generation efficiency may be due to a change of resistivity of the film photoanode that is related with the random distribution of the hetero-junction between interfaces of TiO2 and CuO nanoparticles.

  6. Plasmonic Effect in Au-Added TiO2-Based Solar Cell

    Science.gov (United States)

    Van Hong, Le; Cat, Do Tran; Chi, Le Ha; Thuy, Nguyen Thi; Van Hung, Tran; Tai, Ly Ngoc; Long, Pham Duy

    2016-10-01

    TiO2 nano thin films have been fabricated on fluoride tin oxide (FTO) film electrodes by hydrothermal synthesis at temperatures of 80°C, 120°C, 150°C, and 200°C for different synthesis times of 1 h, 2 h, and 3 h in 2.5 mol, 5 mol, and 7.5 mol NaOH solution. X-ray diffraction patterns and field-emission scanning electron microscopy (FESEM) images were recorded for all the film samples, and the results confirmed that TiO2 anatase phase was generally formed in nanowire form. The influence of synthesis temperature, processing time, and NaOH content on the structure and morphology of the TiO2 material was studied. Au nanoparticles with size of around 2 × 10-8 m were added into the TiO2 thin films by thermal evaporation in vacuum combined with thermal annealing. Based on photocurrent-voltage ( I- V) characteristics measured under irradiation with visible light, the short-circuit current, open-circuit voltage, and efficiency of solar cells with FTO/Au-added TiO2/(I-/I2-) electrolyte/Pt configuration were evaluated. The short-circuit current and efficiency of the Au-added solar cell were greatly improved, which is supposed to be related to a contribution of the surface plasmon resonance effect.

  7. 自持TiO2纳米管阵列薄膜与TiO2/FTO透明光电极制备工艺的研究%INVESTIGATION OF THE FABRICATED TECHNOLOGY OF FREE-STANDING TIO2 NANOTUBE MEMBRANES AND TIO2/FTO TRANSPARENT PHOTOELECTRODE

    Institute of Scientific and Technical Information of China (English)

    张其君; 李燕; 赵雲; 王多书; 王成伟

    2011-01-01

    利用电化学阳极氧化法,采用三步氧化工艺,成功制备出大面积高度有序、孔洞分布均匀、孔道垂直取向且与金属钛基相分离的自持TiO2纳米管阵列膜.然后将其转移粘接至FTO导电玻璃上,形成高度有序的TiO2/FTO纳米管阵列透明光电极.利用场发射扫描电镜、X射线衍射仪、紫外-可见-近红外分光光度计分别对样品的形貌、晶相结构以及光学特性做了表征.研究表明,由三步阳极氧化工艺制备的自持TiO2纳米管阵列膜,其结构参数(如管径、管长及管壁厚度)在很大范围内可控,将其转移粘结至FTO导电玻璃上能制成多种用途的高质量透明光电极;另外,阳极氧化电压对TiO2纳米管阵列薄膜的光学能隙(Eg)也有较为明显的调制作用.显然,这项新工艺对基于TiO2纳米有序阵列复合结构的有机-无机光电器件的应用研究将是非常有益的.%The large-scale, highly-ordered, vertically-oriented free-standing TiO2 nanotube membranes were fabricated by three step anodization Ti foils in ethylene glycol containing 0.25w (NH4F)%. Then the as-prepared free-standing membranes were transferred to FTO-coated glass substrates with TiO2 sol, and the transparent TiO3/FTO photoelectrode was obtained after annealing treatment. The morphologies, crystalline phase, optical properties were characterized using FE-SEM, XRD and UV-Vis-NIR spectrophotometer, respectively. To some extent, the structural parameters of the free-standing TiO2 nanotube membranes (inner diameter, nanotube length, and wall thickness)are controllable. After the membranes were transferred onto the FTO-coated glass substrate, we can obtain the high quality and multi-application TiO3/FTO photoelectrode At the same time, it is found that the optical energy gap(Eg) of TiO2 nanotube membranes could be effectively modulated by different anodic oxidation voltage. Obviously, this work would be beneficial to apply in organic

  8. Formation Process of a TiO2 Inverse Opal

    Institute of Scientific and Technical Information of China (English)

    倪培根; 程丙英; 张道中

    2002-01-01

    Inverse opals of TiO2 with different filling fractions were fabricated by using an opal of polystyrene spheres as a template. Scanning electron microscopy showed the accumulative process of TiO2. The transmission spectra of inverse opals with different filling fractions were measured and the shifts of transmission dip with the filling fraction were observed. Our investigation made the infiltration process clear, and it might be helpful for further improvement of the fabrication of TiO2 inverse opals.

  9. Photoinduced underwater superoleophobicity of TiO2 thin films.

    Science.gov (United States)

    Sawai, Yusuke; Nishimoto, Shunsuke; Kameshima, Yoshikazu; Fujii, Eiji; Miyake, Michihiro

    2013-06-11

    The photoinduced wettabilities of water, n-hexadecane, dodecane, and n-heptane on a flat TiO2 surface prepared by a sol-gel method-based coating were investigated. An amphiphilic surface produced by UV irradiation exhibited underwater superoleophobicity with an extremely high static oil contact angle (CA) of over 160°. The TiO2 surface almost completely repelled the oil droplet in water. A robust TiO2 surface with no fragile nanomicrostructure was fabricated on a Ti mesh with a pore size of approximately 150 μm. The fabricated mesh was found to be applicable as an oil/water separation filter.

  10. High open voltage and superior light-harvesting dye-sensitized solar cells fabricated by flower-like hierarchical TiO2 composed with highly crystalline nanosheets

    Science.gov (United States)

    Que, Ya-Ping; Weng, Jian; Hu, Lin-Hua; Wu, Ji-Huai; Dai, Song-Yuan

    2016-03-01

    The morphology, microstructure and crystallography of titanium dioxide (TiO2) have great effect on the photoelectric performance of dye-sensitized solar cells (DSSCs). Herein, flower-like 3D TiO2 microstructures based on well-defined high-crystalline nanosheets are synthesized through a facile hydrothermal method. Especially, morphological evolution process and mechanism of this hierarchical structure are investigated. Due to the highly crystalline nature and smaller surface area of these nanosheets, the corresponding device shows an extremely high open-current voltage up to 0.84 V, which results from the less electron recombination. When applied as a scattering layer on top of the nanoparticle layer, the power conversion efficiency (PCE) can be significantly improved and give birth to a PCE value of 9.6%, which is 24.6% higher than that of an analogous device using nanoparticles (NP) (7.7%). As reflected by diffusion reflection spectra, intensity of the modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS) and electrochemical impedance spectra (EIS), this hierarchical structure can not only enhance light harvesting, but also reduce electron recombination, facilitate electron transport and improve electron collection efficiency.

  11. Application of the multi-step EPD technique to fabricate thick TiO2 layers: effect of organic medium viscosity on the layer microstructure.

    Science.gov (United States)

    Sadeghi, A A; Ebadzadeh, T; Raissi, B; Ghashghaie, S; Fateminia, S M A

    2013-02-14

    In the present study, electrophoretic deposition (EPD) was used to obtain dense layers of TiO(2) in four organic media-methanol, ethanol, 1-propanol, and butanol-with different TiO(2) nanoparticle concenterations of 1-8 g/L. Microstructural study of the obtained layers by scanning electron (SEM) and optical microscope (OM) revealed that the multistep EPD technique could effectively prevent crack formation across the layer compared with the single-step method and will consequently increase the critical cracking thickness (CCT). The quality of EPD layers was also affected by viscosity. According to SEM and atomic force microscope (AFM) results, as the viscosity of the medium increased, more compact layers were formed which can be attributed to the lower deposition rates in heavier alcohols. High deposition rate in methanol and ethanol was also confirmed by zeta potential results. Suspension viscosity was interestingly observed to control the threshold concentration above which crack formation would occur. These values were measured to be 3 and 5 g/L for methanol and ethanol, respectively. However, in suspensions based on more viscous alcohols, the threshold concentration increased to 8 g/L which implied the decisive role of medium on concentration limits. It indicates that by employing organic vehicles of higher viscosity it is possible to maintain the CCT values obtained in less viscous media with no need to decrease the colloidal concentration of the suspension.

  12. Design and fabrication of SiO2/TiO2 and MgO/TiO2 based high selective optical filters for diffuse reflectance and fluorescence signals extraction.

    Science.gov (United States)

    Pimenta, S; Cardoso, S; Miranda, A; De Beule, P; Castanheira, E M S; Minas, G

    2015-08-01

    This paper presents the design, optimization and fabrication of 16 MgO/TiO2 and SiO2/TiO2 based high selective narrow bandpass optical filters. Their performance to extract diffuse reflectance and fluorescence signals from gastrointestinal tissue phantoms was successfully evaluated. The obtained results prove their feasibility to correctly extract those spectroscopic signals, through a Spearman's rank correlation test (Spearman's correlation coefficient higher than 0.981) performed between the original spectra and the ones obtained using those 16 fabricated optical filters. These results are an important step for the implementation of a miniaturized, low-cost and minimal invasive microsystem that could help in the detection of gastrointestinal dysplasia.

  13. Análise por difração de raios x de filmes de óxidos cerâmicos compostos por IrO2/TiO2/CeO2

    Directory of Open Access Journals (Sweden)

    Alves Valéria Almeida

    2000-01-01

    Full Text Available Independent of the sample form (powder or film, XRD analysis of Ir0,3Ti(0,7-xCe xO2, (nominal mixtures, for x=0, shows the formation of a solid solution phase between IrO2 and TiO2, as well as the rutile phases of IrO2 and TiO2. The presence of the anatase phase of TiO2 is also confirmed. The introduction of 30 mol% CeO2 in the mixture reveals the presence of the CeO2 and Ce2O3 phases, besides the already mentioned ones, in the powder. In the film form, however, an amorphous phase is identified. When all of the TiO2 is substituded by CeO2, for both sample forms, the only phases found are IrO2, CeO2 and Ce2O3. This result suggests cerium oxides are not capable of forming solid solutions with either IrO2 or (Ir,TiO2 acting solely as a dispersant matrix for these phases. These results are consistent with the much higher electrochemically active surface area when CeO2 is introduced in the binary Ti/Ir0,3Ti0,7O2 mixture. It was possible to establish a relationship between the electrochemical stability of the supported films and their crystalline structure. The unexpected presence of TiO2 and Ti2O3 in the Ti/Ir0,3Ce0,7O2 (film sample is attributed to oxidation of the Ti support during the calcination step.

  14. 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 TiO2 (N-TiO2) 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-TiO2 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 TiO2. 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 TiO2 nanorods. Absorption spectra showed higher absorption of visible light for N-TiO2 than un-doped TiO2. 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-TiO2 than to un-doped TiO2. Electrochemical impedance spectroscopy (EIS) showed the smaller resistance of device based on N-TiO2 than that on un-doped TiO2.

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

    Science.gov (United States)

    He, Z.; He, H. Y.

    2011-11-01

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

  16. TiO2 nanofilm growth by Ti ion implantation and thermal annealing in O2 atmosphere

    Institute of Scientific and Technical Information of China (English)

    周小东; 周思华; 孙现科; 张云丽

    2015-01-01

    TiO2 nanofilms on surface of fused silica were fabricated by Ti ion implantation and subsequent thermal annealing in oxygen ambience. The silica glasses were implanted by 20 kV Ti ions to 1.5 × 1017 ions/cm2 on an implanter of metal vapor vacuum arc (MEVVA) ion source. Effects of annealing parameters on formation, growth and phase transformation of the TiO2 nanofilms were studied in detail. Optical absorption spectroscopy, Raman scattering spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and transmis-sion electron microscopy measurements were done to figure out formation mechanism of the TiO2 nanofilms. The formation of TiO2 nanofilms was due to out-diffusion of the implanted Ti ions to the substrate surface, where they were oxidized into TiO2 nanoparticles. Formation, phase, and thickness of the TiO2 nanofilms can be well tailored by controlling annealing parameters.

  17. 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

    2017-01-01

    In this paper, N-doped TiO2 (N-TiO2) 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-TiO2 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 TiO2. 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 TiO2 nanorods. Absorption spectra showed higher absorption of visible light for N-TiO2 than un-doped TiO2. 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-TiO2 than to un-doped TiO2. Electrochemical impedance spectroscopy (EIS) showed the smaller resistance of device based on N-TiO2 than that on un-doped TiO2.

  18. Nitrogen doped TiO2-Cu(x)O core-shell mesoporous spherical hybrids for high-performance dye-sensitized solar cells.

    Science.gov (United States)

    Guo, Enyan; Yin, Longwei

    2015-01-07

    We report on high-performance dye-sensitized solar cells (DSSCs) based on nitrogen doped anatase TiO2-CuxO core-shell mesoporous hybrids synthesized through a facile and controlled combined sol-gel and hydrothermal process in the presence of hexadecylamine as the structure-directing agent. The matching of band edges between CuxO and TiO2 to form a semiconductor heterojunction plays an important role in effective separation of light induced electrons and holes, providing a promising photoanode for DSSCs because of its wide absorption spectrum, high electron injection efficiency, and fast electron transference. DSSCs based on the mesoporous TiO2-CuxO core-shell hybrids show a high short-circuit current density of 9.60 mA cm(-2) and a conversion efficiency of 3.86% under one sun illumination. While DSSCs based on the N-doped mesoporous TiO2-CuxO hybrids exhibit the higher short-circuit current density of 13.24 mA cm(-2) and a conversion efficiency of 4.57% under one sun illumination. In comparison with un-doped TiO2-CuxO hybrids, the doping of nitrogen into the lattice of TiO2 can extend the light absorption in the ultraviolet range to the visible light region and effectively decrease the recombination rate of photo-generated electrons and holes. The presented N-doped mesoporous TiO2-CuxO hybrids as photoanodes could find potential applications for high performance DSSCs.

  19. Promoting effect of TiO2 on the catalytic performance of Pt-Au/TiO2(x)-CeO2 for the co-oxidation of CO and H2 at room temperature

    Science.gov (United States)

    Hong, Xiaowei; Sun, Ye; Zhu, Tianle; Liu, Zhiming

    2017-02-01

    In the present study the promoting effect of TiO2 on the catalytic performance of Pt-Au/TiO2(x)-CeO2 catalysts for the co-oxidation of CO and H2 at room temperature has been investigated. The results showed that the addition of TiO2 to Pt-Au/CeO2 catalyst enhances the activity for the co-oxidation of CO and H2, and Pt-Au/TiO2 (10%)-CeO2 catalyst was the most active catalyst. A series of characterization methods were used to elucidate the promoting effect of TiO2. It was found that the introduction of TiO2 to Pt-Au/CeO2 led to the increase of Ce3+ and Au+ species, both of which played important roles in the co-oxidation of CO and H2. Moreover, a possible mechanism of the simultaneous removal of CO and H2 has been proposed.

  20. TiO2/CuInS2复合纳米棒阵列的制备及其光电性能%Fabrication of CuInS2 Sensitized TiO2 Nanorod Arrays for Photovoltaic Devices

    Institute of Scientific and Technical Information of China (English)

    范俊奇; 周正基; 周文辉; 武四新

    2012-01-01

    采用两步溶剂热法在氧化氟锡(FTO)导电玻璃基底上制备了CuInS2敏化TiO2纳米棒阵列复合薄膜光阳极.利用X射线衍射仪(XRD)和扫描电子显微镜(SEM)表征了复合阵列薄膜的晶体结构和表面形貌,同时采用紫外-可见吸收分光光度计(UV-Vis)及光电流-电压(I-V)曲线研究了CuInS2敏化TiO2纳米阵列薄膜的光学及光电化学性质.研究结果表明,TiO2纳米棒阵列薄膜被CuInS2敏化后在可见光区的吸收有明显的增强.在模拟太阳光照射下(100 mW/cm2),利用这种复合薄膜作为光阳极组装的量子点敏化太阳能电池的开路电压为0.29 V,短路电流密度为0.15 mA/cm2,具有一定的光电转换能力.%Vertically oriented single-crystalline TiO2 nanorod arrays sensitized with CuInS2 quantum dots (QDs) were synthesized directly on fluorine-doped tin oxide (FTO) substrates by two-step solvothermal method. The as-prepared nanostructure assembly was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results indicated that CuInS2 QDs were uniformly covered on the surface of the single-crystalline TiO2 nanorods. Ultraviolet visible (UV-Vis) absorption spectra showed that the absorbance of the TiO2/CuInS2 nanocomposite film was extended to the visible region. Under illumination of simulated AM 1.5 G (100 mW/cm2) at one sun intensity, the QD sensitized solar cells (QD-SSCs) assembled with FTO/TiO2/CuInS2 photoelectrodes exhibited an open-circuit voltage of 0.29 V and a short-circuit current density of 0.15 mA/cm2.

  1. Structural and Optical Properties of Core-Shell TiO2/CdS Prepared by Chemical Bath Deposition

    Science.gov (United States)

    Al-Jawad, Selma M. H.

    2017-10-01

    Titanium dioxide (TiO2) nanorod arrays (NRAs) sensitized with cadmium sulfide (CdS) nanoparticles (NPs) were deposited by chemical bath deposition (CBD). TiO2 NRAs were also obtained by using the same method on glass substrates coated with fluorine-doped tin oxide (FTO). The structure of the FTO/TiO2/CdS core-shell was characterized by x-ray diffraction (XRD), atomic force microscopy, scanning electron microscopy, ultraviolet-visible (UV-Vis) absorption spectroscopy, photoluminescence, and photoelectrocatalysis of FTO/TiO2 and FTO/TiO2/CdS. The FTO/TiO2 conformed to anatase and rutile phase structures for different pH values and also with annealing. XRD patterns of the FTO/TiO2/CdS sample exhibited two peaks corresponding to hexagonal (100) and (101) for CdS. Scanning electron micrographs showed nanorod structures for the TiO2 thin films deposited at a pH value equal 0.7. Optical results showed the CdS deposited on nanorod TiO2 exhibited increased absorption ability in the visible light, indicating an increased photocatalytic activity for TiO2/CdS core-shell nanorods in the visible light. When illuminated with a UV-Vis light source, the TiO2/CdS core-shell films displayed high responses. A composite exists between the TiO2 nanostructure and CdS NPs because the film absorbs the incident light located in both the visible and UV-Vis regions. A higher response to UV-Vis light was attained with the use of TiO2 NRAs/CdS NPs films prepared by CBD. This approach offers a technique for fabricating photoelectrodes.

  2. TiO2 Nanostructure Synthesized by Sol-Gel for Dye Sensitized Solar Cells as Renewable Energy Source

    Science.gov (United States)

    Ramelan, A. H.; Wahyuningsih, S.; Saputro, S.; Supriyanto, E.; Hanif, Q. A.

    2017-02-01

    The use of renewable materials as a constituent of a smart alternative energy such as the use of natural dyes for light harvesting needs to be developed. Synthesis of anatase titanium dioxide (TiO2) and fabrication Dye-Sensitized Solar Cell (DSSC) using dye-based of anthocyanin from purple sweet potato (Ipomoea batatas L.) as a photosensitizer had been done. Synthesis TiO2 through sol-gel process with the addition of triblock copolymer Pluronic F127 template was controlled at pH 3 whereas calcination was carried out at a temperature of 500 °C, 550 °C and 600 °C. The obtained TiO2 were analyzed by XRD, SAA, and SEM. The conclusion is anatase TiO2 obtained until annealing up to 600 °C. Self-assembly Pluronic F127 triblock copolymer capable of restraining the growth of TiO2 crystals. Retention growth of TiO2 mesoporous produces material character that can be used as builders photoanode DSSC with natural sensitizer anthocyanin from purple sweet potatoes. Based on the analysis of X-ray diffraction patterns and surface area analyser, the higher the calcination temperature the greater the size of the anatase crystals is obtained, however, the smaller its surface area. Purple sweet potato anthocyanin’s dyed on to TiO2 was obtained a good enough performance for DSSC’s and gain the optimum performance from DSSC’s system built with mesoporous TiO2 annealed 550 °C using flavylium form anthocyanin.

  3. Double-Shelled TiO2 Hollow Spheres Assembled with TiO2 Nanosheets.

    Science.gov (United States)

    Zhang, Chao; Zhou, Yuming; Zhang, Yiwei; Zhao, Shuo; Fang, Jiasheng; Sheng, Xiaoli; Zhang, Tao; Zhang, Hongxing

    2017-02-08

    High-quality double-shelled TiO2 hollow spheres (DHS-Ti) assembled with TiO2 nanosheets have been synthesized for the first time through a simple hydrothermal treatment of sSiO2 @TiO2 (TiO2 -coated solid SiO2 spheres). The double-shelled structure shows a high BET surface area up to 417.6 m(2)  g(-1) . Anatase DHS-Ti of high crystallinity can be obtained without structural collapse by calcination treatment. The effects of cetyl trimethylammonium bromide (CTAB) concentration, pH, and hydrothermal reaction temperature have also been investigated with a series of contrast experiments. A formation mechanism involving the in situ growth of amorphous TiO2 nanosheets followed by the redeposition of dissolved silica species is proposed. Lastly, the DHS-Ti forming strategy can be extended as a general strategy to fabricate various morphological hollow nanostructures and double-shelled Pt nanocatalysts by rationally selecting functional sSiO2 nanoparticles as core materials. This work could open up a new strategy for controllable synthesis of complex hollow structures and other functional materials.

  4. Transparent conductive electrodes of mixed TiO2−x–indium tin oxide for organic photovoltaics

    KAUST Repository

    Lee, Kyu-Sung

    2012-05-22

    A transparent conductive electrode of mixed titanium dioxide (TiO2−x)–indium tin oxide (ITO) with an overall reduction in the use of indium metal is demonstrated. When used in organic photovoltaicdevices based on bulk heterojunction photoactive layer of poly (3-hexylthiophene) and [6,6]-phenyl C61 butyric acid methyl ester, a power conversion efficiency of 3.67% was obtained, a value comparable to devices having sputtered ITO electrode. Surface roughness and optical efficiency are improved when using the mixed TiO2−x–ITO electrode. The consumption of less indium allows for lower fabrication cost of such mixed thin filmelectrode.

  5. 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.

  6. Photocatalytic degradation of methylene blue under UV light irradiation on prepared carbonaceous TiO2.

    Science.gov (United States)

    Ramli, Zatil Amali Che; Asim, Nilofar; Isahak, Wan N R W; Emdadi, Zeynab; Ahmad-Ludin, Norasikin; Yarmo, M Ambar; Sopian, K

    2014-01-01

    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 m(2) 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.

  7. Fabrication and magnetic properties of Sm3(Fe,Ti)29Nx/α-Fe dual-phase nanocomposite permanent magnetic material

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Sm3(Fe,Ti)29Nx/α-Fe dual-phase nanometer magnetic material was fabricated through rapid solidification, crystallization and nitridation of Sm-Fe (Ti) alloy. The effect of combination of rapid solidification and Ti alloy addition on the phase for- mation and microstructure of the Sm-Fe alloy is investigated in this paper. The mi- crostructure of amorphous phase and dual-phase nano-grain crystals before and after crystallization annealing were observed using a high-resolution transmission electron microscope (HREM). The dual-phase nano-grains after annealing were compacted together with a clear interface with the direct exchange-coupling mechanism. Different annealing processes were used to examine the melt-spun alloy. Comparison of the images of SEM showed that annealing at 750 ℃ for 10 min was most suitable to get homogeneous and nano-grains. No obvious kink was de- tected in the second quadrant of the hysteresis loop like a single hard magnet, and strong exchange coupling was found between hard magnets and soft magnets.

  8. Fabrication and magnetic properties of Sm3(Fe,Ti)29Nx/α-Fe dual-phase nanocomposite permanent magnetic material

    Institute of Scientific and Technical Information of China (English)

    CUI ChunXiang; ZHANG Ying; SUN JiBing; WANG Ru

    2007-01-01

    Sm3(Fe,Ti)29Nx/α-Fe dual-phase nanometer magnetic material was fabricated through rapid solidification, crystallization and nitridation of Sm-Fe (Ti) alloy. The effect of combination of rapid solidification and Ti alloy addition on the phase formation and microstructure of the Sm-Fe alloy is investigated in this paper. The microstructure of amorphous phase and dual-phase nano-grain crystals before and after crystallization annealing were observed using a high-resolution transmission electron microscope (HREM). The dual-phase nano-grains after annealing were compacted together with a clear interface with the direct exchange-coupling mechanism. Different annealing processes were used to examine the melt-spun alloy. Comparison of the images of SEM showed that annealing at 750℃ for 10 min was most suitable to get homogeneous and nano-grains. No obvious kink was detected in the second quadrant of the hysteresis loop like a single hard magnet, and strong exchange coupling was found between hard magnets and soft magnets.

  9. 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.

  10. Interaction of Rh with Rh nanoparticles encapsulated by ordered ultrathin TiO(1+x) film on TiO2(110) surface.

    Science.gov (United States)

    Berkó, A; Gubó, R; Ovári, L; Bugyi, L; Szenti, I; Kónya, Z

    2013-12-23

    Rh films of 5-50 monolayers (ML) were grown on TiO2(110)-(1 × 1) surface by physical vapor deposition (PVD) at 300 K followed by annealing at max. 1050 K. In the coverage range of 5-15 ML, separated stripe-like Rh nanoparticles of approximately 30 × 150 nm lateral size and 10-20 layer thickness with a flat top (111) facet were formed. At higher coverages (15-50 ML), the Rh film sustained its continuity at least up to 950 K. For both cases, the Rh(111) top facets were completely covered by a long-range ordered hexagonal "wagon-wheel" TiO(1+x) ultrathin oxide (hw-TiO-UTO) film. STM-STS, XPS, LEIS, and TDS methods were used for morphologic and electronic characterization of surfaces prepared in this way. The main part of this study is devoted to the study of postdeposition of Rh on the hw-TiO-UTO layer at different temperatures (230 K, 310 K, 500 K) and to the effect of subsequent annealing. It was found that 2D nanoparticles of 0.2-0.3 nm height and 1-2 nm diameter are formed at RT and their average lateral size increases gradually in the range of 300-900 K. The LEIS intensity data and the CO TDS titration of the particles have shown that an exchange of the postdeposited Rh atoms with the hw-TiO-UTO layer proceeds to an extent of around 50% at 230 K and this value increases up to 80-90% in the range of 300-500 K. The total disappearance of the characteristic LEIS signal for Rh takes place at around 900 K where a complete hw-TiO-UTO adlayer forms on top of the postdeposited metal (100% exchange).

  11. Band gap characterization of ternary BBi1-xNx (0≤x≤1) alloys using modified Becke-Johnson (mBJ) potential

    Science.gov (United States)

    Yalcin, Battal G.

    2015-04-01

    The semi-local Becke-Johnson (BJ) exchange-correlation potential and its modified form proposed by Tran and Blaha have attracted a lot of interest recently because of the surprisingly accurate band gaps they can deliver for many semiconductors and insulators (e.g., sp semiconductors, noble-gas solids, and transition-metal oxides). The structural and electronic properties of ternary alloys BBi1-xNx (0≤x≤1) in zinc-blende phase have been reported in this study. The results of the studied binary compounds (BN and BBi) and ternary alloys BBi1-xNx structures are presented by means of density functional theory. The exchange and correlation effects are taken into account by using the generalized gradient approximation (GGA) functional of Wu and Cohen (WC) which is an improved form of the most popular Perdew-Burke-Ernzerhof (PBE). For electronic properties the modified Becke-Johnson (mBJ) potential, which is more accurate than standard semi-local LDA and PBE calculations, has been chosen. Geometric optimization has been implemented before the volume optimization calculations for all the studied alloys structure. The obtained equilibrium lattice constants of the studied binary compounds are in coincidence with experimental works. And, the variation of the lattice parameter of ternary alloys BBi1-xNx almost perfectly matches with Vegard's law. The spin-orbit interaction (SOI) has been also considered for structural and electronic calculations and the results are compared to those of non-SOI calculations.

  12. Tunability of morphological properties of Nd-doped TiO2 thin films

    Science.gov (United States)

    Saleem Bhatti, Arshad; Rehan, Imran; Sultana, Sabiha; Khan, Nauman; Qamar, Zahid; Rehan, Kamran

    2016-11-01

    In this work, an endeavor is made toward structural assessment and morphological variation of titanium dioxide (TiO2) thin films when doped with neodymium (Nd). The electron beam deposition technique was employed to fabricate Nd-based TiO2 thin films on n-Type Si substrates. Nd concentration was varied from 0.0 to 2.0 atomic percent (at.%) under identical growth environments. The films were deposited in an oxygen-deficient environment to cause the growth of rutile phases. Energy dispersive x-ray spectroscopy confirmed the presence and variation of Nd dopant in TiO2. X-ray diffraction analysis showed the transformation of amorphous structures of the as-grown samples to anatase polycrystalline after annealing at 500 °C, while atomic force microscopy exposed linearity in grain density in as-grown samples with doping until 1 at.%. Raman spectrums of as-grown and annealed samples revealed the growth of the anatase phase in the annealed samples. Based on these results it can be proposed that Nd doping has pronounced effects on the structural characteristics of TiO2 thin films.

  13. First-Principle Study of the Structural, Electronic, and Optical Properties of Cubic InNxP1-x Ternary Alloys under Hydrostatic Pressure

    Science.gov (United States)

    Hattabi, I.; Abdiche, A.; Moussa, R.; Riane, R.; Hadji, K.; Soyalp, F.; Varshney, Dinesh; Syrotyuk, S. V.; Khenata, R.

    2016-09-01

    In this article, we present results of the first-principle study of the structural, electronic, and optical properties of the InN, InP binary compounds and their related ternary alloy InNxP1-x in the zinc-blend (ZB) phase within a nonrelativistic full potential linearised augmented plan wave (FP-LAPW) method using Wien2k code based on the density functional theory (DFT). Different approximations of exchange-correlation energy were used for the calculation of the lattice constant, bulk modulus, and first-order pressure derivative of the bulk modulus. Whereas the lattice constant decreases with increasing nitride composition x. Our results present a good agreement with theoretical and experimental data. The electronic band structures calculated using Tran-Blaha-modified Becke-Johnson (TB-mBJ) approach present a direct band gap semiconductor character for InNxP1-x compounds at different x values. The electronic properties were also calculated under hydrostatic pressure for (P=0.00, 5.00, 10.0, 15.0, 20.0, 25.0 GPa) where it is found that the InP compound change from direct to indirect band gap at the pressure P≥7.80 GPa. Furthermore, the pressure effect on the dielectric function and the refractive index was carried out. Results obtained in our calculations present a good agreement with available theoretical reports and experimental data.

  14. Fabrication of Textured Rough SnO2:F Films on Glass Using TiO2 Film as a Buffer Layer

    Science.gov (United States)

    Ren, Yang; Wang, Qiuhong; Zhou, Xiaoge; Gao, Yun; Zhao, Gaoyang

    2017-08-01

    This study proposes an alternative method for preparing SnO2:F films with a pyramid-like surface morphology that are suitable for the transparent electrodes used in amorphous silicon thin-film solar cells. By introducing a TiO2 film as a buffer layer, the crystallographic orientation of the SnO2:F films was changed from random to a (200) plane, and the surface topography of the SnO2:F film transformed from rod-like to pyramid-like; hence, textured, rough SnO2:F films were obtained. An appropriately textured rough surface improves light-trapping and enhances the photocurrent in amorphous silicon thin-film solar cells. The textured SnO2:F films were used as the front electrode in a 1-cm2 single-junction amorphous silicon solar cell yielding an initial efficiency of 9.3%. Light-trapping in the textured SnO2:F films led to a photo-generated current higher than that generated in smooth films.

  15. AMORPHOUS HYDROGENATED ALLOYS : A COMPARATIVE EXAFS STUDY OF a-Si1-xCx : H, a-Si1- xGex : H, a-SiNx : H AT THE SILICON K-EDGE

    OpenAIRE

    1986-01-01

    a-Si1-xCx : H, a-Si1-xGex : H, a-SiNx : H alloys have been studied at the Si K-edge. Si-Si and Si-A (A being C, N, Ge) bond lengths have been determined as a function of composition. The Si-C distance was found to vary significantly, while the Si-Ge and Si-N distances remain almost constant. A high frequency signal has been detected in the a-Si1-xCx : H and a-SiNx : H films at large x due to a second shell contribution. The compositions of the first coordination shell are also reported and di...

  16. Highly active nanocrystalline TiO2 photoelectrodes

    Science.gov (United States)

    Paronyan, Tereza M.; Kechiantz, A. M.; Lin, M. C.

    2008-03-01

    A simple method for the fabrication of highly photoactive nanocrystalline two-layer TiO2 electrodes for solar cell applications is presented. Diluted titanium acetylacetonate has been used as a precursor for covering SnO2:F (FTO) films with dense packed TiO2 nanocrystallites. The nanoporous thick TiO2 film follows the dense packed thin TiO2 film as a second layer. For the latter, amorphous TiO2 nanoparticles have been successfully synthesized by a sol-gel technique in an acidic environment with pHacidic nanoparticle gel was neutralized by basic ammonia and a TiO2 gel of pH 5 was obtained; this pH value is higher than the recently reported value of 3.1 (Park et al 2005 Adv. Mater. 17 2349-53). Highly interconnected, nanoporous, transparent and active TiO2 films have been fabricated from the pH 5 gel. SEM, AFM and XRD analyses have been carried out for investigation of the crystal structure and the size of nanoparticles as well as the surface morphology of the films. Investigation of the photocurrent-voltage characteristics has shown improvement in cell performance along with the modification of the surface morphology, depending on pH of the TiO2 gel. Increasing the pH of the gel from 2.1 to 5 enhanced the overall conversion efficiency of the dye-sensitized solar cells by approximately 30%. An energy conversion efficiency of 8.83% has been achieved for the cell (AM1.5, 100 mWcm-2 simulated sunlight) compared to 6.61% efficiency in the absence of ammonia in the TiO2 gel.

  17. Unusual Changes in Electronic Band-Edge Energies of the Nanostructured Transparent n-Type Semiconductor Zr-Doped Anatase TiO2 (Ti1-xZrxO2; x < 0.3).

    Science.gov (United States)

    Mieritz, Daniel G; Renaud, Adèle; Seo, Dong-Kyun

    2016-07-05

    By the establishment of highly controllable synthetic routes, electronic band-edge energies of the n-type transparent semiconductor Zr-doped anatase TiO2 have been studied holistically for the first time up to 30 atom % Zr, employing powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen gas sorption measurements, UV/vis spectroscopies, and Mott-Schottky measurements. The materials were produced through a sol-gel synthetic procedure that ensures good compositional homogeneity of the materials, while introducing nanoporosity in the structure, by achieving a mild calcination condition. Vegard's law was discovered among the homogeneous samples, and correlations were established between the chemical compositions and optical and electronic properties of the materials. Up to 20% Zr doping, the optical energy gap increases to 3.29 eV (vs 3.19 eV for TiO2), and the absolute conduction band-edge energy increases to -3.90 eV (vs -4.14 eV). The energy changes of the conduction band edge are more drastic than what is expected from the average electronegativities of the compounds, which may be due to the unnatural coordination environment around Zr in the anatase phase.

  18. Growth of TiO2 nanoparticles under heat treatment

    Science.gov (United States)

    Bahadur, J.; Sen, D.; Mazumder, S.; Sastry, P. U.; Paul, B.

    2013-02-01

    The effect of heat treatment, on growth of NiO doped TiO2, have been investigated. The nanoparticle size has been estimated by small-angle x-ray scattering. The average particle size increases with increasing temperature. The growth of crystallite size has been probed by X-ray diffraction. A polymorphic phase transition of TiO2 is observed beyond 600°C due to growth of TiO2 nanoparticles beyond 14 nm of size.

  19. Photocatalytic antibacterial performance of TiO2 and Ag-doped TiO2 against S. aureus. P. aeruginosa and E. coli

    OpenAIRE

    Gupta, Kiran; Singh, R. P.; Pandey, Ashutosh; Pandey, Anjana

    2013-01-01

    This paper reports the structural and optical properties and comparative photocatalytic activity of TiO2 and Ag-doped TiO2 nanoparticles against different bacterial strains under visible-light irradiation. The TiO2 and Ag-doped TiO2 photocatalysts were synthesized by acid catalyzed sol–gel technique and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis spectroscopy and photoluminescence (PL). The XRD pattern revealed that the annealed sample of TiO2 has ...

  20. Composite Electrode SnO2/TiO2 for Dye-Sensitized Solar Cells

    Institute of Scientific and Technical Information of China (English)

    Jiang Bin XIA; Fu You LI; Shu Ming YANG; Chun Hui HUANG

    2004-01-01

    Composite nanoporous electrode SnO2/TiO2 was fabricated for the dye sensitized solar cell (DSSC) with N3 (Cis-Ru). After introducing of TiO2, the open-circuit photovoltage (Voc) was higher than that of the pure SnO2 electrode, while short-circuit photocurrent (Isc) was varied with the ratio of the TiO2. Appropriate content of the TiO2 can be beneficial to the efficiency of the solar cell, and it gives negative impact on the composite electrode when the content of TiO2 is higher.

  1. Enhanced photocatalytic performance of TiO2-ZnO hybrid nanostructures

    OpenAIRE

    Chun Cheng; Abbas Amini; Chao Zhu; Zuli Xu; Haisheng Song; Ning Wang

    2014-01-01

    We studied the photocatalytic properties of rational designed TiO2-ZnO hybrid nanostructures, which were fabricated by the site-specific deposition of amorphous TiO2 on the tips of ZnO nanorods. Compared with the pure components of ZnO nanorods and amorphous TiO2 nanoparticles, these TiO2-ZnO hybrid nanostructures demonstrated a higher catalytic activity. The strong green emission quenching observed from photoluminescence of TiO2-ZnO hybrid nanostructures implied an enhanced charge transfer/s...

  2. Dopamine sensitized nanoporous TiO2 film on electrodes: photoelectrochemical sensing of NADH under visible irradiation.

    Science.gov (United States)

    Wang, Guang-Li; Xu, Jing-Juan; Chen, Hong-Yuan

    2009-04-15

    Dopamine-coordinated photoactive TiO(2) nanoporous films with a wide excitation range of light in the visible region (up to 580 nm) were prepared and used for sensitive detection of NADH. Colloidal TiO(2) was firstly covered on an indium-tin oxide (ITO) electrode surface and sintered at 450 degrees C to form a nanoporous TiO(2) film, then the electrode was dipped in a dopamine solution to form a dopamine-TiO(2) charge transfer complex via coordinating dopamine with undercoordinated titanium atoms on the electrode surface. This charge transfer complex provided an anodic photocurrent under visible light and the photocurrent could be largely enhanced by NADH. The photocurrent enhancement might be due to the electron transfer between NADH and the holes localized on dopamine. A new photoelectrochemical methodology for sensitive detection of NADH at a relatively low potential was developed. The detection limit of NADH was 1.4x10(-7) M, and the detection range could extend up to 1.2x10(-4) M. The dopamine-TiO(2) modified electrode exhibits its major advantages such as effective electronic transducer, fast response and easy fabrication for photoelectrochemical determination of NADH. This strategy largely reduces the destructive effect of UV light and the photogenerated holes of illuminated TiO(2) to biomolecules and opens a new avenue for the applications of TiO(2) in photoelectrochemical biosensing.

  3. Electron Beam Evaporated TiO2 Layer for High Efficiency Planar Perovskite Solar Cells on Flexible Polyethylene Terephthalate Substrates

    KAUST Repository

    Qiu, Weiming

    2015-09-30

    The TiO2 layer made by electron beam (e-beam) induced evaporation is demonstrated as electron transport layer (ETL) in high efficiency planar junction perovskite solar cells. The temperature of the substrate and the thickness of the TiO2 layer can be easily controlled with this e-beam induced evaporation method, which enables the usage of different types of substrates. Here, Perovskite solar cells based on CH3NH3PbI3-xClx achieve power conversion efficiencies of 14.6% on glass and 13.5% on flexible plastic substrates. The relationship between the TiO2 layer thickness and the perovskite morphology is studied with scanning electron microscope (SEM), atomic force microscope (AFM), and X-ray photoelectron spectroscopy (XPS). Our results indicate that pinholes in thin TiO2 layer lead to pinholes in the perovskite layer. By optimizing the TiO2 thickness, perovskite layers with substantially increased surface coverage and reduced pinhole areas are fabricated, increasing overall device performance.

  4. Stereospecific growth of densely populated rutile mesoporous TiO2 nanoplate films: a facile low temperature chemical synthesis approach

    Science.gov (United States)

    Lee, Go-Woon; Ambade, Swapnil B.; Cho, Young-Jin; Mane, Rajaram S.; Shashikala, V.; Yadav, Jyotiprakash; Gaikwad, Rajendra S.; Lee, Soo-Hyoung; Jung, Kwang-Deog; Han, Sung-Hwan; Joo, Oh-Shim

    2010-03-01

    We report for the first time, using a simple and environmentally benign chemical method, the low temperature synthesis of densely populated upright-standing rutile TiO2 nanoplate films onto a glass substrate from a mixture of titanium trichloride, hydrogen peroxide and thiourea in triply distilled water. The rutile TiO2 nanoplate films (the phase is confirmed from x-ray diffraction analysis, selected area electron diffraction, energy-dispersive x-ray analysis, and Raman shift) are 20-35 nm wide and 100-120 nm long. The chemical reaction kinetics for the growth of these upright-standing TiO2 nanoplate films is also interpreted. Films of TiO2 nanoplates are optically transparent in the visible region with a sharp absorption edge close to 350 nm, confirming an indirect band gap energy of 3.12 eV. The Brunauer-Emmet-Teller surface area, Barret-Joyner-Halenda pore volume and pore diameter, obtained from N2 physisorption studies, are 82 m2 g - 1, 0.0964 cm3 g - 1 and 3.5 nm, respectively, confirming the mesoporosity of scratched rutile TiO2 nanoplate powder that would be ideal for the direct fabrication of nanoscaled devices including upcoming dye-sensitized solar cells and gas sensors.

  5. Dye-Sensitized Solar Cell with Photoanode Made with Polystyrene-Ball-Embedded TiO2 Pastes

    Science.gov (United States)

    Hsu, Yu-Ching; Wu, Tony Chang Chi; Cheng, I.-Chun; Chen, Jian-Zhang; Yang, Mu-Rong

    2011-06-01

    We report the effect of varying the concentration of polystyrene (PS) balls embedded in TiO2 paste during the fabrication of TiO2 photoanodes on the performance of dye-sensitized solar cells (DSSCs). We fabricated porous photoanodes using TiO2 pastes mixed with various concentrations of PS balls in aqueous solution. During the TiO2 sintering processes, the PS evaporated, leaving behind large cavities (>1 µm) in the photoanodes. These cavities enhance the scattering of light, leading to improved absorption of light by N3 dyes. DSSC efficiency increases with the increase in PS ball concentration during TiO2 fabrication. As with classical devices, TiCl4 treatment of TiO2 and the use of a compact TiO2 layer both improve the cell efficiency of DSSC devices with our large-cavity TiO2 photoanodes.

  6. Photoanode based on chain-shaped anatase TiO2 nanorods for high-efficiency dye-sensitized solar cells.

    Science.gov (United States)

    Rui, Yichuan; Li, Yaogang; Wang, Hongzhi; Zhang, Qinghong

    2012-10-01

    Anatase TiO(2) nanorods with large specific surface areas and high crystallinity have been synthesized by surfactant-free hydrothermal treatment of water-soluble peroxotitanium acid (PTA). X-ray diffraction and TEM analysis showed that all TiO(2) nanorods derived from PTA in different hydrothermal processes were in the anatase phase, and high aspect ratio TiO(2) nanorods with chain-shaped structures were formed at 150 °C for 24 h by oriented growth. The nanorods were fabricated as photoanodes for high-efficiency dye-sensitized solar cells (DSSCs). DSSCs fabricated from the chain-shaped TiO(2) nanorods gave a highest short-circuit current density of 14.8 mA cm(-2) and a maximum energy conversion efficiency of 7.28 %, as a result of the presence of far fewer surface defects and grain boundaries than are present in commercial P25 TiO(2) nanoparticles. Electrochemical impedance spectroscopy also confirmed that DSSCs based on the TiO(2) nanorods have enhanced electron transport properties and a long electron lifetime. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Electronic structure of FCC-Fe{sub n}X (X=C, N; n=4, 8) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Peltzer y Bianca, E.L. [Grupo de Estudio de Materiales y Dispositivos Electronicos (GEMyDE), Facultad de Ingenieria, UNLP, IFLYSIB-CONICET, C.C. No 565, 1900 La Plata (Argentina)]. E-mail: eitel@iflysib.unlp.edu.ar; Desimoni, J. [Departamento de Fisica, Facultad de Ciencias. Exactas, UNLP, IFLP-CONICET, C.C.No 67, 1900 La Plata (Argentina); Christensen, N.E. [Department of Physics and Astronomy, Aarhus University, Ny Munkegade, Bld. 520, DK-8000 Aarhus C (Denmark)

    2004-12-31

    To obtain a picture of the FCC-FeX (X=C, N) austenite solid solution, we compare the hyperfine parameters obtained by Moessbauer spectroscopy and those obtained by the full-potential linear augmented-plane wave (FLAPW) method. We have focused the study on the magnetic moments, isomer shifts, and hyperfine magnetic fields obtained by FLAPW assuming an Fe{sub 4}X structure to sketch the austenite.

  8. Hydrothermal synthesis of TiO2-ZnO-graphene nanocomposite towards photocatalytic and photovoltaic applications

    Science.gov (United States)

    Gayathri, S.; Jayabal, P.; Ramakrishnan, V.

    2015-06-01

    Titanium dioxide (TiO2) - Zinc oxide (ZnO) - Graphene (G) nanocomposite was successfully synthesized through facile hydrothermal method. The X-ray diffraction (XRD) pattern and the micro-Raman spectroscopic technique revealed the formation of TiO2-ZnO-Graphene (TZG) nanocomposite. The ZnO and TiO2 nanoparticles decorated graphene sheets were clearly noticeable in the Field Emission Scanning Electron Micrograph (FE-SEM). The UV-Visible absorption spectra clearly indicated that the formation of TZG nanocomposite enriched the absorption in the visible region. Hence, the prepared nanocomposite can be used as photocatalyst to remove organic dyes from water and as photoanode in the fabrication of dye sensitized solar cells (DSSCs).

  9. Inorganic Antiflaming Wood Caused by a TiO2-Decorated ZnO Nanorod Arrays Coating Prepared by a Facile Hydrothermal Method

    Directory of Open Access Journals (Sweden)

    Hong Zhang

    2016-01-01

    Full Text Available Wood materials with antiflaming capability were successfully fabricated by depositing a TiO2-decorated ZnO nanorod arrays (ZNAs film on wood surface using a facile and one-pot hydrothermal method. The prepared specimens were characterized by scanning electron microscopy (SEM, energy dispersive X-ray analysis (EDXA, and powder X-ray diffraction (XRD. To explore the antiflaming properties, the combustion parameters of the wood treated by TiO2-decorated ZNAs were measured using the cone calorimetry technique compared with the untreated wood. For treated wood, the burning duration was prolonged for 55 s; smoke production rate (SPR and total smoke production (TSP were obviously reduced, especially for the production of CO was almost zero. As a result, thin inorganic film of TiO2-decorated ZNAs had desirable fire resistance, and one-pot hydrothermal method was a feasible method to fabricate nonflammable wood materials.

  10. Photocatalytic synthesis of TiO(2) and reduced graphene oxide nanocomposite for lithium ion battery.

    Science.gov (United States)

    Qiu, Jingxia; Zhang, Peng; Ling, Min; Li, Sheng; Liu, Porun; Zhao, Huijun; Zhang, Shanqing

    2012-07-25

    In this work, we synthesized graphene oxide (GO) using the improved Hummers' oxidation method. TiO2 nanoparticles can be anchored on the GO sheets via the abundant oxygen-containing functional groups such as epoxy, hydroxyl, carbonyl, and carboxyl groups on the GO sheets. Using the TiO2 photocatalyst, the GO was photocatalytically reduced under UV illumination, leading to the production of TiO2-reduced graphene oxide (TiO2-RGO) nanocomposite. The as-prepared TiO2, TiO2-GO, and TiO2-RGO nanocomposite were used to fabricate lithium ion batteries (LIBs) as the active anode materials and their corresponding lithium ion insertion/extraction performance was evaluated. The resultant LIBs of the TiO2-RGO nanocomposite possesses more stable cyclic performance, larger reversible capacity, and better rate capability, compared with that of the pure TiO2 and TiO2-GO samples. The electrochemical and materials characterization suggest that the graphene network provides efficient pathways for electron transfer, and the TiO2 nanoparticles prevent the restacking of the graphene nanosheets, resulting in the improvement in both electric conductivity and specific capacity, respectively. This work suggests that the TiO2 based photocatalytic method could be a simple, low-cost, and efficient approach for large-scale production of anode materials for lithium ion batteries.

  11. Fabrication and Characteristics of TiO2-ZnO Macroporous Composite Nanomaterials%大孔TiO2-ZnO复合纳米材料的制备及其性能

    Institute of Scientific and Technical Information of China (English)

    刘威; 徐耀维; 谭永佳; 钟伟; 廖宗文

    2011-01-01

    The TiO2-ZnO macroporous composite nanomaterials were prepared successfully by sol-gel method and polystyrene (PS) microspheres templates. The crystal structure and topography of the macroporous nanomaterials were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). The photocatalytic activity was studied while the methyl orange was used as the degradation object. The results show that the PS microspheres synthesized by emulsifier-free emulsion polymerization are uniform with the particle size of 900 nm. With the close-packed PS microspheres template, the diameter of TiO2-ZnO macroporous nanomaterials is about 900 nm and the thickness of the pore wall is about 20 nm. The XRD result indicates that TiO2 in macroporous nanomaterials is the anatase structure. The photocatalytic degradation for macroporous nanomaterials was carried out with the methyl orange as the model of the organic pollutant. The results show that the degradation rate of the methyl orange reaches 91.3% by the TiO2-ZnO macroporous nanomaterials, which is 11.2% higher than that of common TiO2-ZnO nanomaterials without the macroporous structures.%采用溶胶-凝胶法和胶态晶体模板法,制备了大孔TiO2-ZnO复合纳米材料.其晶相结构和形貌特征采用X射线粉末衍射(XRD)、透视电子显微镜(TEM)进行了表征,并以甲基橙为降解对象,对其光催化活性进行了研究.结果表明,采用无皂乳液聚合法得到的聚苯乙烯(PS)微球粒径均匀,为900 nm.以紧密堆积的PS胶态晶体为模板,制得的TiO2-ZnO复合纳米材料的大孔孔径约为900 nm,孔壁厚度约为20 nm.XRD结果显示,材料中的TiO2为锐钛矿型.光催化降解结果表明,大孔TiO2-ZnO复合纳米材料对甲基橙降解1.5 h后降解率可达91.3%,与普通的TiO2-ZnO纳米粉体材料相比提高了11.2%.

  12. Synthesis of ultrathin TiO2/Ti films with tunable structural color.

    Science.gov (United States)

    Wang, Yanlu; Han, Rushuai; Qi, Liqian; Liu, Lihu; Sun, Huiyuan

    2016-12-10

    A series of ultrathin TiO2/Ti films with iridescent structural colors were fabricated on high-purity titanium sheets via a one-step anodization procedure. Tunable color in the films can be obtained by adjusting the anodization time and can be adjusted across the entire visible range. It was found that all the films displayed highly saturated colors. Trichromatic coordinates of color x, y were delineated, and the color was identified by positioning the x and y values in the Commission International de I'Eclairage chromaticity diagram. Theoretical and experimental results of the changes in the structural color according to the principle of complementary colors are consistent with the experimental results. The TiO2/Ti films may have potential in color displays, decoration, and anticounterfeiting technology.

  13. Facile decoration of TiO2 nanoparticles on graphene for solar degradation of organic dye

    Science.gov (United States)

    Salem, Shiva; Salem, Amin; Rezaei, Mostafa

    2016-11-01

    The reduced graphene oxide is interesting material for the synthesis of TiO2-based photocatalyst. In the present investigation, blackberry fruit, which contains high levels of anthocyanins and other phenolic compounds, was employed as a reducing agent mainly due to its high antioxidant capacity. The nano-crystalline TiO2 was decorated on different amounts of graphene oxide with sol-gel method and then the photocatalytic activity for degradation of cationic dye was evaluated by UV spectroscopy to achieve the optimum content of graphene oxide. The decoration of anatase nanoparticles on prepared reduced graphene oxide was investigated by X-ray diffraction, scanning and transmission electron microscopy techniques. The new composite gives significantly higher activity when is compared to the compositions fabricated by graphene oxide. The compact layer provides a large TiO2-graphene contact area and reduces the electron recombination. The decoration of TiO2 nanoparticles, 5-10 nm, on the graphene oxide reduced by blackberry juice further improves the dye removal. The results imply that the nanoparticle decoration is the key strategy to increase the degradation capacity.

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

    Science.gov (United States)

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

    2013-04-01

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

  15. Temperature and Composition Dependence of GaNxAs1-x(0<x≤0.05)before and after Annealing

    Institute of Scientific and Technical Information of China (English)

    赵传阵; 李娜娜; 魏通; 唐春晓

    2011-01-01

    The parameters in the band-anticrossing model for GaNxAsi-x (0NxAs1-x(0<x≤0.05)are obtained considering the effect of temperature and composition.It is found that the effect of composition on the N levels in the band-anticrossing model is weak.The temperature dependence of the N levels and the temperature dependence of the band gap energy of GaNAs are weaker than that of GaAs.In addition,the reason for a spectral blueshift and the effect of annealing on the parameters in the band-anticrossing model are also discussed.

  16. Enhanced Photocatalytic Removal of Uranium(VI) from Aqueous Solution by Magnetic TiO2/Fe3O4 and Its Graphene Composite.

    Science.gov (United States)

    Li, Zijie; Huang, Zhiwei; Guo, Wenlu; Wang, Lin; Zheng, Lirong; Chai, Zhifang; Shi, Weiqun

    2017-04-14

    The separation and recovery of uranium from radioactive wastewater is important from the standpoints of environmental protection and uranium reuse. In the present work, magnetically collectable TiO2/Fe3O4 and its graphene composites were fabricated and utilized for the photocatalytical removal of U(VI) from aqueous solutions. It was found that, under ultraviolet (UV) irradiation, the photoreactivity of TiO2/Fe3O4 for the reduction of U(VI) was 19.3 times higher than that of pure TiO2, which is strongly correlated with the Fe0 and additional Fe(II) generated from the reduction of Fe3O4 by TiO2 photoelectrons. The effects of initial uranium concentration, solution pH, ionic strength, the composition of wastewater, and organic pollutants on the U(VI) removal by TiO2/Fe3O4 were systematically investigated. The results demonstrated its excellent performance in the cleanup of uranium contamination. As graphene can efficiently attract the TiO2 photoelectrons and thus decrease their transfer to Fe3O4, the photodissolution of Fe3O4 in the TiO2/graphene/Fe3O4 composite can be largely alleviated compared to that of the TiO2/Fe3O4, rendering this ternary composite a much higher stability. In addition, scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray absorption near edge spectroscopy (XANES), and X-ray photoelectron spectroscopy (XPS) were used to explore the reaction mechanisms.

  17. Structural and Electrical Properties of TiO2 Thin Film Derived from Sol-gel Method using Titanium (IV Butoxide

    Directory of Open Access Journals (Sweden)

    Isrihetty Senain

    2010-12-01

    Full Text Available Fabrication of titanium dioxide (TiO2 thin film on microscope glass using sol-gel method has been studied intensively. The starting materials were titanium (IV butoxide, ethanol, acetic acid, triton x-100, hydrochloric acid and deionized water. The materials were mixed together to form the sols. Then, the heat and ageing treatment was applied to form stable sols. The sols were then spin coated on the glass substrate to form the homogenous and transparent TiO2 thin film. The TiO2 thin film was coated at several layers using specific conditions. To evaluate the performance of thin film, the crystallinity of the thin film was determined by using the x-ray diffractometer  (XRD. The change on the surface morphology was observed using atomic force microscope (AFM. The electrical property of the thin film was determined by doing the current-voltage (I-V analysis on the thin film. It has been successfully shown that the anatase crystalline phase was observed when the TiO2 thin film was heated at 500°C. The roughness and the crystalline phase of TiO2 thin film changed drastically with the growth conditions. Finally, the effect of film preparation to the film resistivity also showed a critical aspect where we should take into account during the preparation of TiO2 thin film.

  18. Highly active nanocrystalline TiO(2) photoelectrodes.

    Science.gov (United States)

    Paronyan, Tereza M; Kechiantz, A M; Lin, M C

    2008-03-19

    A simple method for the fabrication of highly photoactive nanocrystalline two-layer TiO(2) electrodes for solar cell applications is presented. Diluted titanium acetylacetonate has been used as a precursor for covering SnO(2):F (FTO) films with dense packed TiO(2) nanocrystallites. The nanoporous thick TiO(2) film follows the dense packed thin TiO(2) film as a second layer. For the latter, amorphous TiO(2) nanoparticles have been successfully synthesized by a sol-gel technique in an acidic environment with pHTiO(2) gel of pH 5 was obtained; this pH value is higher than the recently reported value of 3.1 (Park et al 2005 Adv. Mater. 17 2349-53). Highly interconnected, nanoporous, transparent and active TiO(2) films have been fabricated from the pH 5 gel. SEM, AFM and XRD analyses have been carried out for investigation of the crystal structure and the size of nanoparticles as well as the surface morphology of the films. Investigation of the photocurrent-voltage characteristics has shown improvement in cell performance along with the modification of the surface morphology, depending on pH of the TiO(2) gel. Increasing the pH of the gel from 2.1 to 5 enhanced the overall conversion efficiency of the dye-sensitized solar cells by approximately 30%. An energy conversion efficiency of 8.83% has been achieved for the cell (AM1.5, 100  mWcm(-2) simulated sunlight) compared to 6.61% efficiency in the absence of ammonia in the TiO(2) gel.

  19. Morphological influence of TiO2 nanostructures (nanozigzag, nanohelics and nanorod) on photocatalytic degradation of organic dyes

    Science.gov (United States)

    Khan, Sadaf Bashir; Hou, Mengjing; Shuang, Shuang; Zhang, Zhengjun

    2017-04-01

    Hierarchical nanostructures have drawn significant attention and incredible performance in photodriven chemical conversion area due to its unique physicochemical properties. Herein, we study the morphological influence of TiO2 nanostructures on photocatalytic degradation of different organic dyes methyl blue, methyl violet and methyl orange present in industrial wastewater. Nanorod, nanohelics and nanozigzag TiO2 nanofilms were fabricated by using galancing angle deposition technique (GLAD). TiO2 nanofilms were characterized by scanning electron microscope (SEM), X-ray powder diffraction (XRD), and raman analysis. BET surface area analysis were carried out by using nitrogen adsorption desorption curves. The results show that TiO2 morphology had great influence on photocatalytic degradation of organic dyes due to difference in specific surface area and pore volume of nanostructures. The photocatalytic degradation experiments were carried out for three hours under UV-vis light irradiation. Catalysis recycling and organic dyes concentration influence were also studied. In case of high concentration of organic dyes, negligible degradation rate is observed. TiO2 nanozigzag films show better degradation performance than nanohelics and nanorod due to presence of large surface area for reaction, higher porosity with dispersion of active sites at different length scales of pores and presence of oxygen vacancies.

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

    Science.gov (United States)

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

    2012-06-01

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

  1. In situ loading of CuS nanoflowers on rutile TiO2 surface and their improved photocatalytic performance

    Science.gov (United States)

    Lu, Y. Y.; Zhang, Y. Y.; Zhang, J.; Shi, Y.; Li, Z.; Feng, Z. C.; Li, C.

    2016-05-01

    CuS nanoflowers, fabricated by an element-direct-reaction route using copper and sulfur powder, were loaded on rutile TiO2 (CuS/TiO2) at low temperature. CuS/TiO2 composites were utilized as the photocatalysts for the degradation of Methylene Blue (MB) and 4-chlorophenol (4-CP). X-ray diffraction (XRD), UV Raman spectroscopy, transmission electron microscopy (TEM), XPS, and UV-visible diffuse reflectance spectra were used to characterize the crystalline phase, morphology, particle size, and the optical properties of CuS/TiO2 samples. It is found that CuS/TiO2 photocatalyst, which CuS are loaded on the surface of rutile TiO2, exhibited enhanced photocatalytic degradation of MB (or 4-CP) than TiO2 or CuS. This indicates that CuS can enhance effectively the photocatalytic activity of rutile TiO2 by forming heterojunction between CuS and rutile TiO2, which is confirmed by photoluminescence (PL) spectra and TEM. Moreover, CuS content has a significant influence on photocatalytic activity and 2 wt% CuS/TiO2 showed the maximum photocatalytic activity for degradation of MB.

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

    Science.gov (United States)

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

    2016-06-29

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

  3. Enhanced photocatalytic performance of TiO2-ZnO hybrid nanostructures

    Science.gov (United States)

    Cheng, Chun; Amini, Abbas; Zhu, Chao; Xu, Zuli; Song, Haisheng; Wang, Ning

    2014-02-01

    We studied the photocatalytic properties of rational designed TiO2-ZnO hybrid nanostructures, which were fabricated by the site-specific deposition of amorphous TiO2 on the tips of ZnO nanorods. Compared with the pure components of ZnO nanorods and amorphous TiO2 nanoparticles, these TiO2-ZnO hybrid nanostructures demonstrated a higher catalytic activity. The strong green emission quenching observed from photoluminescence of TiO2-ZnO hybrid nanostructures implied an enhanced charge transfer/separation process resulting from the novel type II heterostructures with fine interfaces. The catalytic performance of annealing products with different TiO2 phase varied with the annealing temperatures. This is attributed to the combinational changes in Eg of the TiO2 phase, the specific surface area and the quantity of surface hydroxyl groups.

  4. Preparation of High-Orderly TiO2 Nanotubes in Organic Solution and Characterization of C-doped TiO2

    Science.gov (United States)

    Fan, Xiao-yan; Zhang, Yun-huai; Xiao, Peng; Hu, Fu; Zhang, Huai

    2007-12-01

    High-orderly TiO2 nanotube arrays were fabricated by anodic oxidation of pure titanium substrate in organic electrolyte containing fluoride. Different morphological nanotubes of titania were obtained through controlling the different anodization voltages and durations. The length of the longest nanotubes was approximately 60 μm and the length-to-width aspect ratio was about 600. The nanotube layers were then annealed at different temperatures (450, 550, and 650°C) in air for 2 h. The samples were characterized by scanning electron microscopy, X-ray diffraction (XRD), energy dispersive X-Ray (EDS) and UV-Vis spectrometer. The XRD results demonstrated that the as-anodized samples were amorphous and the structure changed to antanse and rutile when the samples were annealed at higher temperature. The EDS microanalysis indicated the presence of carbon in the TiO2 nanotubes. The result of degradation of methylene blue showed clearly that the photocatalytic activity of C-doped TiO2 nanotubes increased by 10%.

  5. STS study of TiO2 film and Pt-deposited TiO2 film in air

    Institute of Scientific and Technical Information of China (English)

    Zhang Min; Jin Zhensheng

    2004-01-01

    Direct investigation of the electronic structure of catalyst surfaces on the near-atomic scale in general has not been impossible in the past. However, with the advent of the scanning tunneling microscope (STM), the opportunity arises for incorporating the scanning tunneling spectroscopy (STS) for correlation in-situ surface electronic structure with topography on a sub-nanometer scale. In this paper, we report the STS results of thin film TiO2 and Pt-deposited TiO2 annealed at 450℃. It was found that the TiO2 semiconductor changes from n-type to p-type after Pt deposition.Fig. 1 shows the surface electronic property (Ⅰ-Ⅴ curve) of thin TiO2 film measured in air by STS. A steep descent of the anodic tunneling current at ca.- 1.0 Ⅴ and a rapid ascent of cathodic tunneling current at ca. +2.0V. The zero bias represents the Fermi level (Ef). Ef is situated at the Ecb side indicating that the thin TiO2 film possesses the same band gap as that of bulk TiO2 phase ( Egs =3.0 to 3.2 eV). For the sample of Pt-deposited TiO2 film, Pt/(Pt+Ti+O) atomic ratio≈0.2, which indicates that the surface of TiO2 film is partly covered by Pt particles, and there are two types of Ⅰ-Ⅴ curves to be detected. One of them (Fig.2a)is attributed to the electronic property of TiO2, which has same Egs as that shown in Fig. 1. However, the Ef is transferred to valence side (△≈1eV). This phenomenon hints that TiO2 is doped by an impurity which can introduce h+ into TiO2 lattice.Such a type of defects may be described by Ti1-xPtxO2(h )2x, here Pt+2 as a substitutional site of Ti+4. Fig.2b is the Ⅰ-Ⅴ curve of a Pt particle situated on a TiO2 particle contained Ti1-xPtxO2(h )2x.

  6. TiO2 nanotube arrays made by magnetron sputtering and the fabricated hybrid solar cells%磁控溅射TiO2纳米管阵列与其组装的杂化太阳能电池∗

    Institute of Scientific and Technical Information of China (English)

    任鑫; 曹娇; 施利毅

    2014-01-01

    采用直流磁控溅射-热处理二步法在多孔阳极氧化铝模板上制备出 TiO2纳米管阵列膜。将纳米管阵列膜转移到 ITO 导电玻璃,并分别与 P3 HT 和P3 HT∶PCBM组装成杂化太阳能电池。通过扫描电镜、X射线衍射仪、能谱仪和模拟太阳光光电性能测试系统化对TiO2纳米管阵列膜和其组装的太阳能电池进行了分析表征。在纳米管阵列膜和 ITO 玻璃之间加入TiO2结合层的 P3 HT∶PCBM基杂化太阳能电池表现出最好的转换效率。该方法制备的大面积TiO2纳米管阵列膜,纯度高、工艺稳定,在未来的聚合物太阳能电池商业化应用中具有巨大潜力。%TiO2 nanotube arrays were made by DC magnetron sputtering-heat treatment two step method. Then,the nanotube arrays were transferred onto the ITO substrates,and were fabricated to hybrid solar cells with P3 HT and P3 HT∶PCBM,respectively.Scanning electron microscopy,X-ray diffraction,energy disper-sive spectrometer and photovoltaic measurement system were used to characterized and analyzed the TiO2 nano-tube arrays and the corresponding solar cells.The best conversion efficiency was obtained from the P3 HT∶PCBM/TiO2 nanotube based solar cell with a TiO2 binding layer between the nanotubular film and the ITO sub-strate.The two step method shows a great potential in the commercial application of the polymer solar cells.

  7. Hollow TiO2 modified reduced graphene oxide microspheres encapsulating hemoglobin for a mediator-free biosensor.

    Science.gov (United States)

    Liu, Hui; Guo, Kai; Duan, Congyue; Dong, Xiaonan; Gao, Jiaojiao

    2017-01-15

    Hollow TiO2 modified reduced graphene oxide microspheres (hollow TiO2-rGO microspheres or H-TiO2-rGO MS) have been synthesized and then be used to immobilize hemoglobin (Hb) to fabricate a mediator-free biosensor. The morphology and structure of hollow TiO2-rGO microspheres were characterized by scanning electron microscopy, transmission electronic microscopy and X-ray diffraction. Results of spectroscopy and electrochemistry tests revealed that hollow TiO2-rGO microsphere is an excellent immobilization matrix with biocompatibility for redox protein, affording good protein bioactivity and stability. The hollow TiO2-rGO microspheres with special structure and component enhance the immobilization efficiency of proteins and facilitate the direct electron transfer, which result in the better H2O2 detection performance-the wide linear range of 0.1-360μM for H2O2 (sensitivity of 417.6 μA mM(-1) cm(-2)) and the extremely low detection limit of 10nM for H2O2. Moreover, the hollow microsphere can provide a protective microenvironment for Hb to make the as-prepared biosensor improve long-term stability. The as-prepared biosensor retains 95.4% of the initial response to H2O2 after 60-d storage. Hence, this work suggests that if can be fabricated a mediator-free biosensor, hollow TiO2-rGO microspheres will find wide potential applications in environmental analysis and biomedical detection.

  8. Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

    Institute of Scientific and Technical Information of China (English)

    GAO Yu-zhou; ZHANG Hui-chen; WANG Liang; YAN Li

    2004-01-01

    TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.

  9. Thickness Effect of Nb-Doped TiO2 Transparent Conductive Oxide Grown on Glass Substrates Fabricated by RF Sputtering

    Science.gov (United States)

    Tseng, Zong-Liang; Chen, Lung-Chien; Tang, Jian-Fu; Shih, Meng-Fu; Chu, Sheng-Yuan

    2017-03-01

    Transparent conducting Nb-doped titanium oxide (NTO) films were deposited on a non-alkali glass substrate using an RF magnetron sputtering method with post-annealing. Structural, electrical and optical properties of the NTO films were found to be strongly dependent on film thickness. A resistivity of 4.2 × 10-3 Ω cm and an average visible transmittance of ˜70% were obtained at the film thickness of 360 nm, indicating that the polycrystalline NTO fabricated by the sputtering method has sufficient potential as a transparent conducting oxide (TCO) candidate for practical applications.

  10. Thickness Effect of Nb-Doped TiO2 Transparent Conductive Oxide Grown on Glass Substrates Fabricated by RF Sputtering

    Science.gov (United States)

    Tseng, Zong-Liang; Chen, Lung-Chien; Tang, Jian-Fu; Shih, Meng-Fu; Chu, Sheng-Yuan

    2016-12-01

    Transparent conducting Nb-doped titanium oxide (NTO) films were deposited on a non-alkali glass substrate using an RF magnetron sputtering method with post-annealing. Structural, electrical and optical properties of the NTO films were found to be strongly dependent on film thickness. A resistivity of 4.2 × 10-3 Ω cm and an average visible transmittance of ˜70% were obtained at the film thickness of 360 nm, indicating that the polycrystalline NTO fabricated by the sputtering method has sufficient potential as a transparent conducting oxide (TCO) candidate for practical applications.

  11. Thermoelectric Properties in the TiO2/SnO2 System

    Science.gov (United States)

    Dynys, F.; Sayir, A.; Sehirlioglu, A.; Berger, M.

    2009-01-01

    Nanotechnology has provided a new interest in thermoelectric technology. A thermodynamically driven process is one approach in achieving nanostructures in bulk materials. TiO2/SnO2 system exhibits a large spinodal region with exceptional stable phase separated microstructures up to 1400 C. Fabricated TiO2/SnO2 nanocomposites exhibit n-type behavior with Seebeck coefficients greater than -300 .V/K. Composites exhibit good thermal conductance in the range of 7 to 1 W/mK. Dopant additions have not achieved high electrical conductivity (<1000 S/m). Formation of oxygen deficient composites, TixSn1-xO2-y, can change the electrical conductivity by four orders of magnitude. Achieving higher thermoelectric ZT by oxygen deficiency is being explored. Seebeck coeffcient, thermal conductivity, electrical conductance and microstructure will be discussed in relation to composition and doping.

  12. Immobilization of TiO2 nanofibers on reduced graphene sheets: Novel strategy in electrospinning.

    Science.gov (United States)

    Pant, Hem Raj; Adhikari, Surya Prasad; Pant, Bishweshwar; Joshi, Mahesh K; Kim, Han Joo; Park, Chan Hee; Kim, Cheol Sang

    2015-11-01

    A simple and efficient approach is developed to immobilize TiO2 nanofibers onto reduced graphene oxide (RGO) sheets. Here, TiO2 nanofiber-intercalated RGO sheets are readily produced by two-step procedure involving the use of electrospinning process to fabricate TiO2 precursor containing polymeric fibers on the surface of GO sheets, followed by simultaneous TiO2 nanofibers formation and GO reduction by calcinations. GO sheets deposited on the collector during electrospinning/electrospray can act as substrate on to which TiO2 precursor containing polymer nanofibers can be deposited which give TiO2 NFs doped RGO sheets on calcinations. Formation of corrugated structure cavities of graphene sheets decorated with TiO2 nanofibers on their surface demonstrates that our method constitutes an alternative top-down strategy toward fabricating verities of nanofiber-decorated graphene sheets. It was found that the synthesized TiO2/RGO composite revealed a remarkable increased in photocatalytic activity compared to pristine TiO2 nanofibers. Therefore, engineering of TiO2 nanofiber-intercalated RGO sheets using proposed facile technique can be considered a promising method for catalytic and other applications.

  13. Characteristics and Photocatalytic Properties of TiO2 Thin Film Prepared by Sputter Deposition and Post-N+ Ion Implantation

    Directory of Open Access Journals (Sweden)

    Haider A. Shukur

    2012-01-01

    Full Text Available TiO2 thin films of a rutile, an anatase, and a mixture type with anatase and rutile were fabricated by a magnetron sputtering method. The fabricated films were irradiated by N+ ions with several doses using the Freeman ion source. Atomic force microscopy (AFM, X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, and UV-VIS spectrophotometer were employed to investigate morphology, structure, chemical state, and optical characteristics, respectively. Photocatalytic activity was evaluated by degradation of a methylene blue solution using UV and visible light. TiO2 thin films with each structure irradiated by N+ ions showed the different N concentration in the same N+ ion dose and the chemical state of XPS results suggested that an O atom in TiO2 lattice replaced by an N atom. Therefore the photocatalytic activity of TiO2 thin films was improved under visible light. The maximum photocatalytic activity of TiO2 thin films with each structure was indicated at N concentration of 2.1% for a rutile type, of 1.0% for an anatase type, and of 3.8% for a mixture type under the condition of 2.5×1015 ions/cm2 in N+ ion dose.

  14. Atomic Layer Deposition of p-Type Epitaxial Thin Films of Undoped and N-Doped Anatase TiO2.

    Science.gov (United States)

    Vasu, K; Sreedhara, M B; Ghatak, J; Rao, C N R

    2016-03-01

    Employing atomic layer deposition, we have grown p-type epitaxial undoped and N-doped anatase TiO2(001) thin films on c-axis Al2O3 substrate. From X-ray diffraction and transmission electron microscopy studies, crystallographic relationships between the film and the substrate are found to be (001)TiO2//(0001)Al2O3 and [1̅10]TiO2//[011̅0]Al2O3. N-doping in TiO2 thin films enhances the hole concentration and mobility. The optical band gap of anatase TiO2 (3.23 eV) decreases to 3.07 eV upon N-doping. The epitaxial films exhibit room-temperature ferromagnetism and photoresponse. A TiO2-based homojunction diode was fabricated with rectification from the p-n junction formed between N-doped p-TiO2 and n-TiO2.

  15. 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.

  16. Tunable Optical Properties and Charge Separation in CH3NH3Sn(x)Pb(1-x)I3/TiO2-Based Planar Perovskites Cells.

    Science.gov (United States)

    Feng, Hong-Jian; Paudel, Tula R; Tsymbal, Evgeny Y; Zeng, Xiao Cheng

    2015-07-01

    A sharp potential drop across the interface of the Pb-rich halide perovskites/TiO2 heterostructure is predicted from first-principles calculations, suggesting enhanced separation of photoinduced charge carriers in the perovskite-based photovoltaic solar cells. The potential drop appears to be associated with the charge accumulation at the polar interface. More importantly, on account of both the β phase structure of CH3NH3Sn(x)Pb(1-x)I3 for x Pb(1-x)I3 for x ≥ 0.5, the computed optical absorption spectra from time-dependent density functional theory (TD-DFT) are in very good agreement with the measured spectra from previous experiments. Our TD-DFT computation also confirms the experimental structures of the mixed Pb-Sn organometal halide perovskites. These computation results provide a highly sought answer to the question why the lead-based halide perovskites possess much higher power conversion efficiencies than the tin-based counterparts for solar-cell applications.

  17. Photochemical generation of H2NCNX, H2NNCX, H2NC(NX) (X = O, S) in low-temperature matrices.

    Science.gov (United States)

    Vörös, Tamás; Lajgút, Győző György; Magyarfalvi, Gábor; Tarczay, György

    2017-01-14

    The [NH2, C, N, O] and the [NH2, C, N, S] molecular systems were investigated by computational and matrix-isolation spectroscopic methods. The determination of the equilibrium structures and relative energies by CCSD(T) method was followed by the computation of the harmonic and anharmonic vibrational wavenumbers, infrared intensities, relative Raman activities, and UV excitation energies. These computed data were used to assist the identification of products obtained by UV laser photolysis of 3,4-diaminofurazan and 3,4-diaminothiadiazole in low-temperature Ar and Kr matrices. It is shown that two open-chain H2NNCX and H2NCNX and one cyclic H2NC(NX) (X = O, S) isomers are generated in the case of both systems. Except for H2NNCO and H2NCNS, the present study reports the first generation and spectroscopic identification of these compounds.

  18. The Reactivity and Structure of Size Selected VxO y Clusters on a TiO2 (110)-(1 X 1) Surface of Variable Oxidation State

    Science.gov (United States)

    Neilson, Hunter L.

    The Reactivity and Structure of Size Selected VxOy Clusters on a TiO2 (110) Surface of Variable Oxidation State by Hunter L Neilson The selective oxidative dehydrogenation of methanol by vanadium oxide/TiO2 model systems has received a great deal of interest in the surface science community. Previous studies using temperature programmed desorption and reaction (TPD/R) to probe the oxidation of methanol to formaldehyde by vanadia/TiO2 model catalysts have shown that the activity of these systems vary considerably based on the way in which the model system is prepared with formaldehyde desorption temperatures observed anywhere from room temperature to 660 K. The principle reason for this variation is that the preparation of sub-monolayer films of vanadia on TiO2 produces clusters with a multitude of VxOy structures and a mixture of vanadium oxidation states. As a result the stoichiometry of the active vanadium oxide catalyst as well as the oxidation state of vanadium in the active catalyst remain unknown. To better understand this system, our group has probed the reactivity and structure of size-selected Vx, VOy and VxOy clusters on a reduced TiO2 (110) support in ultra-high vacuum (UHV) via TPD/R and scanning tunneling microscopy (STM). Ex situ preparation of these clusters in the gas phase prior to deposition has allowed us to systematically vary the stoichiometry of the vanadia clusters; a layer of control not available via the usual routes to vanadium oxide. The most active catalysts are shown to have (VO3)n stoichiometry in agreement with the theoretical models of the Metiu group. We have shown that both the activity and selectivity of V2O6 and V3O9 cluster catalysts depend sensitively on the oxidation state of the TiO2 (110) support. For example, V2O6 on a reduced surface is selective for the oxidation of methanol to formaldehyde while the selectivity shifts to favor methyl formate as the surface becomes increasingly oxidized. STM studies show that the structure of size-selected V2O6 clusters, upon adsorption to the surface, varies considerably with the oxidation state of the support, in good agreement with our reactivity studies. V 3O9 was shown to catalyze the oxidation of methanol to both formaldehyde and methyl formate on a reduced surface while STM suggests that, unlike V2O6, these clusters are prone to decomposition upon adsorption to the surface. Furthermore, TPD/R of size selected V 2O5 and V2O7 on TiO2 suggests that altering the stoichiometry of the (VO3)n clusters by a single oxygen atom significantly inhibits the activity of these catalysts.

  19. Photocatalytic Oxidation of Diethyl Sulfide Vapor over TiO2-Based Composite Photocatalysts

    Directory of Open Access Journals (Sweden)

    Dmitry Selishchev

    2014-12-01

    Full Text Available Composite TiO2/activated carbon (TiO2/AC and TiO2/SiO2 photocatalysts with TiO2 contents in the 10 to 80 wt. % range were synthesized by the TiOSO4 thermal hydrolysis method and characterized by AES, BET, X-ray diffraction and FT-IR ATR methods. All TiO2 samples were in the anatase form, with a primary crystallite size of about 11 nm. The photocatalytic activities of the TiO2/AC and TiO2/SiO2 samples were tested in the gas-phase photocatalytic oxidation (PCO reaction of diethyl sulfide (DES vapor in a static reactor by the FT-IR in situ method. Acetaldehyde, formic acid, ethylene and SO2 were registered as the intermediate products which finally were completely oxidized to the final oxidation products – H2O, CO2, CO and SO42− ions. The influence of the support on the kinetics of DES PCO and on the TiO2/AC and TiO2/SiO2 samples’ stability during three long-term DES PCO cycles was investigated. The highest PCO rate was observed for TiO2/SiO2 photocatalysts. To evaluate the activity of photocatalysts the turnover frequency values (TOF were calculated for three photocatalysts (TiO2, TiO2/AC and TiO2/SiO2 for the same amount of mineralized DES. It was demonstrated that the TOF value for composite TiO2/SiO2 photocatalysts was 3.5 times higher than for pure TiO2.

  20. Photocatalytic oxidation of diethyl sulfide vapor over TiO2-based composite photocatalysts.

    Science.gov (United States)

    Selishchev, Dmitry; Kozlov, Denis

    2014-12-19

    Composite TiO2/activated carbon (TiO2/AC) and TiO2/SiO2 photocatalysts with TiO2 contents in the 10 to 80 wt. % range were synthesized by the TiOSO4 thermal hydrolysis method and characterized by AES, BET, X-ray diffraction and FT-IR ATR methods. All TiO2 samples were in the anatase form, with a primary crystallite size of about 11 nm. The photocatalytic activities of the TiO2/AC and TiO2/SiO2 samples were tested in the gas-phase photocatalytic oxidation (PCO) reaction of diethyl sulfide (DES) vapor in a static reactor by the FT-IR in situ method. Acetaldehyde, formic acid, ethylene and SO2 were registered as the intermediate products which finally were completely oxidized to the final oxidation products - H2O, CO2, CO and SO42- ions. The influence of the support on the kinetics of DES PCO and on the TiO2/AC and TiO2/SiO2 samples' stability during three long-term DES PCO cycles was investigated. The highest PCO rate was observed for TiO2/SiO2 photocatalysts. To evaluate the activity of photocatalysts the turnover frequency values (TOF) were calculated for three photocatalysts (TiO2, TiO2/AC and TiO2/SiO2) for the same amount of mineralized DES. It was demonstrated that the TOF value for composite TiO2/SiO2 photocatalysts was 3.5 times higher than for pure TiO2.

  1. Photocatalytic antibacterial performance of Sn(4+)-doped TiO(2) thin films on glass substrate.

    Science.gov (United States)

    Sayilkan, Funda; Asiltürk, Meltem; Kiraz, Nadir; Burunkaya, Esin; Arpaç, Ertuğrul; Sayilkan, Hikmet

    2009-03-15

    Pure anatase, nanosized and Sn(4+) ion doped titanium dioxide (TiO(2)) particulates (TiO(2)-Sn(4+)) were synthesized by hydrothermal process. TiO(2)-Sn(4+) was used to coat glass surfaces to investigate the photocatalytic antibacterial effect of Sn(4+) doping to TiO(2) against gram negative Escherichia coli (E. coli) and gram positive Staphylococcus aureus (S. aureus). Relationship between solid ratio of TiO(2)-Sn(4+) in coatings and antibacterial activity was reported. The particulates and the films were characterized using particle size analyzer, zeta potential analyzer, Brunauer-Emmett-Teller (BET), X-ray diffractometer (XRD), SEM, AAS and UV/VIS/NIR techniques. The results showed that TiO(2)-Sn(4+) is fully anatase crystalline form and easily dispersed in water. Increasing the solid ratio of TiO(2)-Sn(4+) from 10 to 50% in the coating solution increased antibacterial effect.

  2. 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.

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

    Science.gov (United States)

    Chorfi, H.; Saadoun, M.; Bousselmi, L.; Bessais, B.

    2012-06-01

    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.

  4. Facile Fabrication of Multifunctional Hybrid Silk Fabrics with Controllable Surface Wettability and Laundering Durability.

    Science.gov (United States)

    Chen, Fengxiang; Yang, Huiyu; Liu, Xin; Chen, Dongzhi; Xiao, Xingfang; Liu, Keshuai; Li, Jing; Cheng, Fan; Dong, Binhai; Zhou, Yingshan; Guo, Zhiguang; Qin, Yong; Wang, Shimin; Xu, Weilin

    2016-03-02

    To obtain a hydrophobic surface, TiO2 coatings are deposited on the surface of silk fabric using atomic layer deposition (ALD) to realize a hierarchical roughness structure. The surface morphology and topography, structure, and wettability properties of bare silk fabric and TiO2-coated silk fabrics thus prepared are evaluated using scanning electron microscopy (SEM), field-emission scanning electron microscopy (FESEM), scanning probe microscope (SPM), X-ray diffraction (XRD), static water contact angles (WCAs), and roll-off angles, respectively. The surfaces of the silk fabrics with the TiO2 coatings exhibit higher surface roughnesses compared with those of the bare silk fabric. Importantly, the hydrophobic and laundering durability properties of the TiO2-coated silk fabrics are largely improved by increasing the thickness of the ALD TiO2 coating. Meanwhile, the ALD process has a litter effect on the service performance of silk fabric. Overall, TiO2 coating using an ALD process is recognized as a promising approach to produce hydrophobic surfaces for elastic materials.

  5. Effects of Homogenization Scheme of TiO2 Screen-Printing Paste for Dye-Sensitized Solar Cells

    OpenAIRE

    Seigo Ito; Kaoru Takahashi; Shin-ich Yusa; Takahiro Imamura; Kenji Tanimoto

    2012-01-01

    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) a...

  6. Combining the UV-switchability of Keggin ions with a galvanic replacement process to fabricate TiO2-polyoxometalate-bimetal nanocomposites for improved surface enhanced raman scattering and solar light photocatalysis.

    Science.gov (United States)

    Pearson, Andrew; Bhosale, Sheshanath; Bhargava, Suresh K; Bansal, Vipul

    2013-08-14

    While the decoration of TiO2 surfaces with metal nanoparticles has been well-established, the modification of the composition of metal nanoparticles postdeposition onto TiO2 surfaces and applicability of such bimetallic systems for surface enhanced Raman scattering (SERS) and photocatalysis has not hitherto been investigated. In this work, we, for the first time, combine the unique UV-switchability of the Keggin ions of 12-phosphotungstic acid (PTA) to directly form metal nanoparticles (Ag and Cu) onto the colloidal TiO2 surface, with a galvanic replacement process to convert these predeposited metal nanoparticles into bimetallic systems (Ag/Au, Ag/Pt, Cu/Au, Cu/Pt, and Cu/Ag). We further demonstrate the applicability of these novel TiO2-polyoxometalate-bimetal nanocomposites toward improved SERS and solar light photocatalysis.

  7. Fabrications of TiO2 Photoanodes for Flexible Dye-sensitized Solar Cells%柔性染料敏化太阳能电池TiO2光阳极的制备

    Institute of Scientific and Technical Information of China (English)

    陈蔚; 刘阳桥; 罗建强; 靳喜海; 孙静; 高濂

    2014-01-01

    Flexible dye-sensitized solar cell (FDSSC) is a type of dye-sensitized solar cell (DSSC) based on flexible substrates, such as plastics and metals, etc. The advantages of FDSSC over rigid DSSC involve bendability, lower cost, ease of large-scale production and wider application, which make it attract much attention. The fabrication methods for FDSSC photoanodes are generally categorized to low-temperature fabrications and high-temperature fabrications, in-cluding chemical additive method, mechanical compression, electrophoretic deposition, lift-off method, and some new technologies. This paper reviewed the above fabrication methods and the performance of the cells was discussed by taking into account the mechanisms for electron transfer and recombination. Finally, the future development of FDSSC was prospected.%柔性染料敏化太阳能电池(Flexible Dye-Sensitized Solar Cell, FDSSC)是以聚合物或金属等柔性材料为基底的染料敏化太阳能电池(Dye-Sensitized Solar Cell, DSSC)。相比于刚性DSSC,其具有可弯曲、低成本、易大面积加工和应用范围广等优点,越来越受到人们的关注。柔性染料敏化太阳能电池 TiO2光阳极的制备方法,根据热处理温度的不同可以分为低温和高温制备方法,其中包括化学法、压力法、电泳沉积法、转移法、金属基底上的制备以及一些新的制备方法等。本文结合DSSC光阳极中电子的传输和复合的基本原理,针对电极的各制备方法进行了综述,并对电池的相关性能作了一定的介绍;最后,对FDSSC未来的发展前景和有潜力的研究方向进行了展望。

  8. Preparation of Photocatalytic TiO2 and TiO2-SiO2 Particles and Application to Degradation of Trace Organics in Aqueous Solution

    Institute of Scientific and Technical Information of China (English)

    周亚松

    2003-01-01

    TiO2 and TiO2-SiO2 photocatalysts were prepared by sol-gel and supercritical CO2 fluid drying method and characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), etc. Their catalytic properties were tested through the photocatalytic degradation of phenol and aniline in wastewater. The results show that the developed fluidized photocatalytic reactor (FPR) and TiO2 catalyst had better performance in degrading pollutants as compared with slurry photocatalytic reactor (SPR) and commercial TiO2 catalyst. The composition and crystal form of TiO2-SiO2 composite oxide had obvious influence on catalytic effect and TiO2-SiO2 photocatalysts showed better catalytic activity and stability.

  9. Controlled fabrication of ordered macroporous TiO2 bilayer films for the photoanode in dye-sensitized solar cells%有序大孔TiO2双层膜的设计合成及其在染料敏化太阳能电池中的应用

    Institute of Scientific and Technical Information of China (English)

    唐昭芳; 陈志刚

    2013-01-01

    以垂直沉积法制备的聚苯乙烯(polystyrene,PS)胶体晶体为模板,钛酸四异丙酯为钛源,通过浸渍-煅烧工艺制备了具有分层次有序结构的大孔TiO2双层膜,并作为光阳极应用于染料敏化太阳能电池(dye-sensitized solar cells,DSSCs).采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、紫外-可见漫反射光谱仪和氮气吸附-脱附分析仪等手段对样品进行了表征.结果表明,有序大孔TiO2薄膜较好地复制了PS模板的三维有序结构,且有较大的比表面积.光电性能测试结果表明,与以纯P25薄膜为光阳极的DSSCs相比,有序大孔TiO2双层膜为光阳极能够明显提高DSSCs的光电转换效率,可从4.16%提高到6.08%.该类型分层次有序结构大孔TiO2双层膜在DSSCs中具有重要的潜在应用价值.%Hierarchical ordered macroporous TiO2 bilayer films were successfully prepared by using 1S colloidal crystal as templates and using tetraisopropyl titanate as titanium source.We use vertical deposition method for fabrication PS colloidal crystal templates.The obtained samples were applied as the photoanode in the dye-sensitized solar cells (DSSCs) after dipping and calcination procedures.The as-synthesized products were characterized by scanning electron microscope (SEM),X-ray diffractometer (XRD),high resolution transmission electron microscope (HRTEM) and nitrogen adsorption-desorption analyzer.The results showed that the macroporous TiO2 films replicated well the three-dimensionally ordered structure derived from PS colloidal crystal templates and revealed a relatively large specific surface area.The photoelectric test results indicated that the photovoltaic conversion efficiency was improved from 4.16% to 6.08%,as compared to a device using a pure P25 TiO2 photoanode.Our results showed that the hierarchically ordered macroporous TiO2 bilayer films photoanode had important and potential applications in DSSCs.

  10. Growth and characterization of hydroxyapatite nanorice on TiO2 nanofibers

    KAUST Repository

    Chetibi, Loubna

    2014-04-01

    Hydroxyapatite (HA) coating with nanoparticles like nanorice is fabricated on chemically pretreated titanium (Ti) surface, through an electrochemical deposition approach, for biomaterial applications. The Ti surface was chemically patterned 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 nanoparticles like nanorice. The obtained samples were annealed at high temperature to produce inter diffusion between TiO2 and HA layers. The resultant layers were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), Infrared Spectroscopy (FTIR), corrosion tests in SBF solution, and Electron Probe Micro Analysis (EPMA). It was found that only Ti from the titanium substrate diffuses into the HA coating and a good corrosion resistance in simulated body fluid was obtained. © 2014 Elsevier B.V. All rights reserved.

  11. Mesoporous TiO2 Nanowire Film for Dye-Sensitized Solar Cell.

    Science.gov (United States)

    Xiao, Li; Xu, Jia; Liu, Xiu; Zhang, Yongzhe; Zhang, Bing; Yao, Jianxi; Dai, Songyuan; Tan, Zhanao; Pan, Xu

    2016-06-01

    In this work, TiO2 nanowire arrays were grown on fluorine-doped tin oxide (FTO) glass substrate, and then were converted into mesoporous nanowires (MNWs). The TiO2 MNWs are about 5 μm in length and 30-200 nm in diameter, with mesopores size of 5-30 nm randomly distributed on the NW surface. X-ray diffraction pattern reports show that the NWs are single crystallized rutile TiO2 and oriented grown along [001]. Through further characterization of FT-IR and TG-DSC, we proposed a reasonable explanation for pore existence. After dye-sensitized solar cells (DSSCs) assembly, the photoelectric conversion efficiency (PCE) of MNWs based DSSC achieved 3.2%. It means tenfold enhancement of photoelectric property compare with the as-grown NWs. Furthermore, dye absorb capacity of MNWs can reach up to 4.11 x 10(-8) mol/cm2. However, such MNWs can not only provide quick and efficient electron transmission channel, but also owns big specific surface area to absorb abundant dyes, thus conducive to fabricate solar cell with a high PCE.

  12. Surface constructions of nano TiO_2 as the environmental and energy materials

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    TiO_2 has attracted an increasing attention because of its variety of potential applications in environments and energies,such as gas sensing,self-cleaning,solar energy conversion, wettability and photo-catalysis applications.In this presentation,we summarize some progress in surface constructions of nano TiO_2 and its characterizations of physicochemistry and properties. (1)Superhydrophobic nanostructure TiO_2 films Superhydrophobic nanotube,nanopore and sponge-like structure TiO_2 films are fabricated ...

  13. MC3T3-E1 Cell Response to Ti1-xAgx and Ag-TiNx Electrodes Deposited on Piezoelectric Poly(vinylidene fluoride) Substrates for Sensor Applications.

    Science.gov (United States)

    Marques, S M; Rico, P; Carvalho, I; Gómez Ribelles, J L; Fialho, L; Lanceros-Méndez, S; Henriques, M; Carvalho, S

    2016-02-17

    In the sensors field, titanium based coatings are being used for the acquisition/application of electrical signals from/to piezoelectric materials. In this particular case, sensors are used to detect dynamic mechanical loads at early stages after intervention of problems associated with prostheses implantation. The aim of this work is to select an adequate electrode for sensor applications capable, in an initial stage to avoid bone cell adhesion, but at a long stage, permit osteointegration and osteoinduction. This work reports on the evaluation of osteoblast MC3T3-E1 cells behavior in terms of proliferation, adhesion and long-term differentiation of two different systems used as sensor electrodes: Ti1-xAgx and Ag-TiNx deposited by d.c. and pulsed magnetron sputtering at room temperature on poly(vinylidene fluoride) (PVDF). The results indicated an improved effect of Ag-TiNx electrodes compared with Ti1-xAgx and TiN, in terms of diminished cell adhesion and proliferation at an initial cell culture stage. Nevertheless, when cell culture time is longer, cells grown onto Ag-TiNx electrodes are capable to proliferate and also differentiate at proper rates, indicating the suitability of this coating for sensor application in prostheses devices. Thus, the Ag-TiNx system was considered the most promising electrode for tissue engineering applications in the design of sensors for prostheses to detect dynamic mechanical loads.

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

    Science.gov (United States)

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

    2014-08-01

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

  15. Optimization of Solar Photocatalytic Degradation of Chloroxylenol Using TiO2, Er3+/TiO2, and Ni2+/TiO2 via the Taguchi Orthogonal Array Technique

    Directory of Open Access Journals (Sweden)

    Ahmed J. Mohammed

    2016-10-01

    Full Text Available In this study, the optical properties of a TiO2 photocatalyst were enhanced with various impregnations of Er3+ and Ni2+ separately, using the impregnation method as photocatalysts for the direct solar photolysis degradation of chloroxylenol. The synthesized Er3+/TiO2 and Ni2+/TiO2 catalysts were characterized using X-ray diffraction (XRD, field emission scanning electron microscopy (FESEM, energy dispersive X-ray (EDX, metal mapping, and ultraviolet visible (UV–Vis spectroscopy. The results showed that the Er3+/TiO2 and Ni2+/TiO2 nano-particles have the same structures of TiO2 nano-particles with little difference in particle size. The Er3+ and Ni2+ ions were well-distributed on the TiO2 surface, and it was found that the maximum band gap decreased from 3.13 eV for intrinsic TiO2 to 2.63 eV at 1.8 wt % Er3+/TiO2 and to 2.47 eV at 0.6 wt % for Ni2+/TiO2. The initial concentration of chloroxylenol, catalyst loading, and pH of the solution are the most important factors affecting the solar photocatalytic degradation efficiency that were optimized using Design Expert software (version 6.0.10, Minneapolis, MN, USA, 2003. The results showed that the optimal conditions for chloroxylenol degradation include a pH of 4, TiO2 loading at 3 g/L, and a chloroxylenol concentration of 50 mg/L. These conditions resulted in a degradation efficiency of 90.40% after 60 min of direct solar irradiation, wherein the solar energy recorded during a clear sunny day is 1000 W/m2. However, some experiments were conducted on a semi-cloudy day to cover all weather stated and to study the degradation kinetics. During semi-cloudy day experiments, using Er3+/TiO2 and Ni2+/TiO2 with a solar irradiation activity of 600 W/m2 for a 60 min exposure at optimal conditions increased the degradation efficiency from 68.28% for intrinsic TiO2 to 82.38% for Er3+/TiO2 and 80.70% for Ni2+/TiO2.

  16. Performance of Erbium-doped TiO2 thin film grown by physical vapor deposition technique

    Science.gov (United States)

    Lahiri, Rini; Ghosh, Anupam; Dwivedi, Shyam Murli Manohar Dhar; Chakrabartty, Shubhro; Chinnamuthu, P.; Mondal, Aniruddha

    2017-09-01

    Undoped and Erbium-doped TiO2 thin films (Er:TiO2 TFs) were fabricated on the n-type Si substrate using physical vapour deposition technique. Field emission scanning electron microscope showed the morphological change in the structure of Er:TiO2 TF as compared to undoped sample. Energy dispersive X-ray spectroscopy (EDX) confirmed the Er doping in the TiO2 thin film (TF). The XRD and Raman spectrum showed the presence of anatase phase TiO2 and Er2O3 in the Er:TiO2 TF. The Raman scattering depicted additional number of vibrational modes for Er:TiO2 TF due to the presence of Er as compared to the undoped TiO2 TF. The UV-Vis absorption measurement showed that Er:TiO2 TF had approximately 1.2 times more absorption over the undoped TiO2 TF in the range of 300-400 nm. The main band transition, i.e., the transition between the oxygen (2p) state and the Ti (3d) state was obtained at 3.0 eV for undoped TiO2 and at 3.2 eV for Er:TiO2 TF, respectively. The photo responsivity measurement was done on both the detectors, where Er:TiO2 TF detector showed better detectivity ( D *), noise equivalent power and temporal response as compared to undoped detector under ultra-violet illumination.

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

    Science.gov (United States)

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

    2015-03-01

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

  18. A facile and versatile method for preparation of colored TiO2 with enhanced solar-driven photocatalytic activity.

    Science.gov (United States)

    Tan, Huaqiao; Zhao, Zhao; Niu, Mang; Mao, Chengyu; Cao, Dapeng; Cheng, Daojian; Feng, Pingyun; Sun, Zaicheng

    2014-09-07

    Colored TiO2 has attracted enormous attention due to its visible light absorption and excellent photocatalytic activity. In this report, we develop a simple and facile solid-state chemical reduction approach for a large-scale production of colored TiO2 at mild temperature (300-350 °C). The obtained sample possesses a crystalline core/amorphous shell structure (TiO2@TiO2-x). The oxygen vacancy results in the formation of a disordered TiO2-x shell on the surface of TiO2 nanocrystals. XPS and theoretical calculation results indicate that valence band tail and vacancy band below the conduction band minimum appear for the TiO2-x, which implies that the TiO2@TiO2-x nanocrystal has a narrow band gap and therefore leads to a broad visible light absorption. Oxygen vacancy in a proper concentration promotes the charge separation of photogenerated carriers, which improves the photocatalytic activity of TiO2@TiO2-x nanocrystals. This facile and general method could be potentially used for large scale production of colored TiO2 with remarkable enhancement in the visible light absorption and solar-driven H2 production.

  19. Joint Effects of Photoactive TiO2 and Fluoride-Doping on SnO2 Inverse Opal Nanoarchitecture for Solar Water Splitting.

    Science.gov (United States)

    Gun, Yun; Song, Gwang Yeom; Quy, Vu Hong Vinh; Heo, Jaeyeong; Lee, Hyunjung; Ahn, Kwang-Soon; Kang, Soon Hyung

    2015-09-16

    Inverse opal (IO) films of tin dioxide (SnO2) were fabricated on polystyrene (PS) beads (diameter=350 nm (±20 nm) with a spin coating method. To compensate for the large band gap (Eg=3.8 eV), a thin TiO2 shell was deposited on the SnO2-IO films with atomic layer deposition (ALD), which produced shells with thicknesses of 10-40 nm. The morphological changes and crystalline properties of the SnO2 and TiO2-coated SnO2 (herein after referred to as TiO2/SnO2) IO films were investigated with field-emission scanning electron microscopy and X-ray diffraction, respectively. The photoelectrochemical (PEC) behavior of the samples was tested in a 0.1 M KOH solution under 1 sun illumination (100 mW/cm2 with an AM 1.5 filter). The highest PEC performance was obtained with the TiO2(10 nm)/SnO2 IO films, which produced a photocurrent density (Jsc) of 4.67 mA/cm2 at 0.5 V (vs NHE) and was sequentially followed by the TiO2(20 nm)/SnO2-IO, TiO2(30 nm)/SnO2-IO, TiO2 (40 nm)/SnO2-IO and SnO2 IO films. Overall, the thin TiO2 shell covered on the SnO2-IO core enhanced Jsc by 3 orders of magnitude, which in turn the PEC activity. This is mainly ascribed to the extremely low charge-transfer resistance (Rct) in the photoelectrode/electrolyte and at the TiO2/SnO2 interface, as well as the contribution of the photoactive TiO2 layer, which has an Eg of 3.2 eV. Moreover, to improve the electrical conductivity of the core SnO2 IO film, the films were doped with 10 mol % of F. The F- doped films were labeled as the FTO IO film. The Rct of the FTO-IO films decreased because of the improved electronic conductivity, enhancing the PEC performance of the TiO2(10 nm)/FTO-IO films by approximately 20%. The core-shell nanowire mesh nanoarchitecture is therefore suggested to provide an insight for designing the peculiar structure based on the material's properties and the engineering of their band gap energy for highly efficient PEC performance.

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

    Science.gov (United States)

    Wang, Qingqing; Dong, Xianjun; Pang, Zengyuan; Du, Yuanzhi; Xia, Xin; Wei, Qufu; Huang, Fenglin

    2012-01-01

    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. PMID:23235446

  1. 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.

  2. Fabrication and characterization of perovskite-based CH3NH3Pb1-xAsxI3+xCly photovoltaic devices

    Science.gov (United States)

    Hamatani, Tsuyoshi; Shirahata, Yasuhiro; Ohishi, Yuya; Fukaya, Misaki; Oku, Takeo

    2017-01-01

    Effects of AsI3 and NH4Cl addition to perovskite CH3NH3PbI3 precursor solutions on photovoltaic properties were investigated. TiO2/CH3NH3Pb(As)I3(Cl)-based photovoltaic devices were fabricated by a spin-coating technique, and the microstructures of the devices were investigated by X-ray diffraction and scanning electron microscopy. Current density-voltage characteristics and incident photon-to-current conversion efficiencies were improved by a small amount of As- and Cl-doping, which resulted in improvement of the efficiencies of the devices.

  3. Tuning hydrophobicity of TiO2 layers with silanization and self-assembled nanopatterning.

    Science.gov (United States)

    Van, Trong Nghia; Lee, Young Keun; Lee, Jaesang; Park, Jeong Young

    2013-03-05

    The wettability of TiO2 layers is controlled by forming highly ordered arrays of nanocones using nanopatterning, based on self-assembly and dry etching. Nanopatterning of TiO2 layers is achieved via formation of self-assembled monolayers of SiO2 spheres fabricated using the Langmuir-Blodgett technique, followed by dry etching. Three types of TiO2 layers were fabricated using the sol-gel technique, sputtering, and thermal process in order to address the relationship between the wettability and the structure of TiO2 nanostructures. Compared to a thin film TiO2 layer, the nanopatterned TiO2 samples show a smaller static water contact angle (i.e., where the water contact angle decreases as the etching time increases), which is attributed to the Wenzel equation. When TiO2 layers are coated by 1H,1H,2H,2H-perfluorooctyltrichlorosilane, we observed the opposite behavior, exhibiting superhydrophobicity (up to contact angle of 155°) on the nanopatterned TiO2 layers. Self-assembled nanopatterning of the TiO2 layer may provide an advanced method for producing multifunctional transparent layers with self-cleaning properties.

  4. Influence of TiO2 nanostructures on the optical absorption of organic-inorganic perovskite

    Science.gov (United States)

    Liu, Zongyi; Ye, Mao; Ostrowski, Michel; Yi, Ya Sha

    2016-04-01

    This work aims to reveal the strong influence of TiO2 nanostructures on the light absorption property of TiO2 and perovskite mixture. Three TiO2 nanostructures, i.e., nanoparticles (S1), ultrapure nanorods (S2), and ultrasmall nanorods (S3), were studied: S1 was selected as a baseline; S2 and S3 were synthesized from S1 by using modified hydrothermal processes. Mesoporous TiO2 thin films were spin-coated from solutions containing these TiO2 nanorods and nanoparticles (S1 as baseline). Organic-inorganic hybrid perovskite CH3NH3PbI3 was then incorporated into these mesoporous TiO2 thin films. Optical absorption results showed that the perovskite mixture with ultrasmall TiO2 nanostructures (S3) has significantly higher optical absorption coefficient. Finite-difference time domain models were built based on three distinct nanostructures of TiO2 and CH3NH3PbI3 mixtures fabricated (S1 to S3) to understand their optical absorption properties. Our work is promising to fabricate TiO2 nanostructures, as a backbone structure, for a series of applications including photovoltaics and photodetection.

  5. Visible light photocatalysis via 3D-ordered macroporous TiO2 films sensitized with CdS quantum dots.

    Science.gov (United States)

    Xie, Hao; Zeng, Tao; Jin, Shaofen; Li, Yuanzhi; Wang, Xuelai; Sui, Xiaotao; Zhao, Xiujian

    2013-02-01

    CdS quantum dots (QDs)-sensitized TiO2 film with three-dimensionally (3D) ordered macropores was synthesized via a two-step method on ITO glass substrate. 3D-ordered macroporous TiO2 film was firstly fabricated on an ITO glass via layer-by-layer deposition and hydrolysis of tetrabutyl titanate using 3D-ordered latex film as organic template, followed by calcination at 450 degrees C for 2 h to remove the template. Then, the CdS QDs were deposited on the 3D-ordered macroporous TiO2 film by successive ionic layer adsorption and reaction technique. The as-prepared CdS-sensitized TiO2 film was characterized with X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, diffusive reflectance UV-visible absorption spectra, and photoelectrochemical measurements. Its photocatalytic activity was evaluated by the photocatalytic degradation of crystal violet aqueous solution at ambient temperature. It was revealed in our results that the CdS QDs-sensitized 3D-ordered macroporous TiO2 film exhibits enhanced photocatalytic activity for the photodegradation of crystal violet than that of the CdS-free 3D-ordered macroporous TiO2 film and that of CdS QD-sensitized TiO2 film without 3D-ordered macropores under the irradiation of visible light due to the co-existence of 3D-ordered interconnected macropores and the sensitization of CdS QDs.

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

    Science.gov (United States)

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

    2008-10-30

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

  7. Solar photocatalytic disinfection of E. coli and bacteriophages MS2, ΦX174 and PR772 using TiO2, ZnO and ruthenium based complexes in a continuous flow system.

    Science.gov (United States)

    Mac Mahon, Joanne; Pillai, Suresh C; Kelly, John M; Gill, Laurence W

    2017-05-01

    The performance of photocatalytic treatment processes were assessed using different photocatalysts against E. coli and bacteriophages MS2, ΦX174 and PR772, in a recirculating continuous flow compound parabolic collector system under real sunlight conditions. Suspended TiO2 and ZnO nanoparticle powders and Tris(2,2'-bipyridyl)dichlororuthenium(II) hexahydrate in solution were tested separately, as well as in combination, using E. coli. For a 3-log reduction of E. coli in distilled water, inactivation rates in terms of cumulative dose were in the order Ru(bpy)3Cl2>(TiO2 & Ru(bpy)3Cl2)>(ZnO & Ru(bpy)3Cl2)>ZnO>TiO2>photolysis. Reactivation of E. coli was observed following all trials despite the detection limit being reached, although the reactivated colonies were observed to be under stress and much slower growing when compared to original colonies. Treatment with Ru(bpy)3Cl2 was also compared against standard photolysis of bacteriophages MS2, ΦX174 and PR772 with the order of photolytic inactivation for a 3-log reduction in terms of cumulative UV-A dose being ΦX174>PR772>MS2. However, MS2 was found to be the most susceptible bacteriophage to treatment with Ru(bpy)3Cl2, with complete removal of the phage observed within the first 15min of exposure. Ru(bpy)3Cl2 also significantly improved inactivation rates for PR772 and ΦX174. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Photocatalytic antibacterial performance of TiO2 and Ag-doped TiO2 against S. aureus. P. aeruginosa and E. coli.

    Science.gov (United States)

    Gupta, Kiran; Singh, R P; Pandey, Ashutosh; Pandey, Anjana

    2013-01-01

    This paper reports the structural and optical properties and comparative photocatalytic activity of TiO2 and Ag-doped TiO2 nanoparticles against different bacterial strains under visible-light irradiation. The TiO2 and Ag-doped TiO2 photocatalysts were synthesized by acid catalyzed sol-gel technique and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis spectroscopy and photoluminescence (PL). The XRD pattern revealed that the annealed sample of TiO2 has both anatase and rutile phases while only an anatase phase was found in Ag-doped TiO2 nanoparticles. The decreased band-gap energy of Ag-doped TiO2 nanoparticles in comparison to TiO2 nanoparticles was investigated by UV-vis spectroscopy. The rate of recombination and transfer behaviour of the photoexcited electron-hole pairs in the semiconductors was recorded by photoluminescence. The antimicrobial activity of TiO2 and Ag-doped TiO2 nanoparticles (3% and 7%) was investigated against both gram positive (Staphylococcus aureus) and gram negative (Pseudomonas aeruginosa, Escherichia coli) bacteria. As a result, the viability of all three microorganisms was reduced to zero at 60 mg/30 mL culture in the case of both (3% and 7% doping) concentrations of Ag-doped TiO2 nanoparticles. Annealed TiO2 showed zero viability at 80 mg/30 mL whereas doped Ag-TiO2 7% showed zero viability at 40 mg/30 mL culture in the case of P. aeruginosa only.

  9. Photocatalytic antibacterial performance of TiO2 and Ag-doped TiO2 against S. aureus. P. aeruginosa and E. coli

    Directory of Open Access Journals (Sweden)

    Kiran Gupta

    2013-06-01

    Full Text Available This paper reports the structural and optical properties and comparative photocatalytic activity of TiO2 and Ag-doped TiO2 nanoparticles against different bacterial strains under visible-light irradiation. The TiO2 and Ag-doped TiO2 photocatalysts were synthesized by acid catalyzed sol–gel technique and characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, UV–vis spectroscopy and photoluminescence (PL. The XRD pattern revealed that the annealed sample of TiO2 has both anatase and rutile phases while only an anatase phase was found in Ag-doped TiO2 nanoparticles. The decreased band-gap energy of Ag-doped TiO2 nanoparticles in comparison to TiO2 nanoparticles was investigated by UV–vis spectroscopy. The rate of recombination and transfer behaviour of the photoexcited electron–hole pairs in the semiconductors was recorded by photoluminescence. The antimicrobial activity of TiO2 and Ag-doped TiO2 nanoparticles (3% and 7% was investigated against both gram positive (Staphylococcus aureus and gram negative (Pseudomonas aeruginosa, Escherichia coli bacteria. As a result, the viability of all three microorganisms was reduced to zero at 60 mg/30 mL culture in the case of both (3% and 7% doping concentrations of Ag-doped TiO2 nanoparticles. Annealed TiO2 showed zero viability at 80 mg/30 mL whereas doped Ag-TiO2 7% showed zero viability at 40 mg/30 mL culture in the case of P. aeruginosa only.

  10. PHOTOCATALYTIC EFFICIENCY OF N-TIO2 APPLIED ON COTTON KNIT – PART 1

    Directory of Open Access Journals (Sweden)

    DUMITRESCU Iuliana

    2016-05-01

    Full Text Available The main aim of the research work is the development of photocatalytic textiles materials by treating them with TiO2 doped with nitrogen. Also, the research was focused on the nitrogen-doped titanium dioxide (N-TiO2 formulation as homogeneous, stable solution, immobilization of large quantities of N-TiO2 on 100% cotton knit while preserving its genuine properties, minimize the loss of nanoparticles in wastewaters and achieve a high photocatalytic fabrics effects under visible light. The photocatalytic effect was investigated by exposing the materials to ultraviolet and visible light, and the evaluation of exposed and non-exposed fabrics was performed using a spectroscopic method. By using scanning electron microscopy, we investigated the characteristic, morphology and distribution of nanoparticles covering the textile materials, and the presence of Ti and Fe on textile materials was analyzed by X-ray energy dispersive spectroscopy and FTIR spectroscopy. The results showed the relatively uniform coating of cotton fibers by particles by using initial and re-used N-TiO2 dispersions. By using additives like polyethylene glycols and wetting agents, the stability of aqueous N-TiO2 is increased. Wetting agents, together with a higher treatment temperature represent important factors contributing to the deposition of increased amount of N-TiO2 particles existing in the dispersion remained after the first treatment of the fabric. Key words: nitrogen-doped TiO2, photocatalysis, cotton fabric, nanoparticles, scanning electron microscopy.

  11. Preparation of N-Doped TiO2-ZrO2 Composite Films under Electric Field and Heat Treatment and Assessment of Their Removal of Methylene Blue from Solution

    Directory of Open Access Journals (Sweden)

    Lefu Mei

    2014-01-01

    Full Text Available TiO2-ZrO2 composite film with the grain size of 50 nm was synthesized by electric field and heat (EF&H treatments. Portions of O atoms in the TiO2 network structure were replaced by N atoms as revealed by X-ray photoelectron spectroscopy (XPS and X-ray diffraction (XRD analyses, suggesting formation of a nonstoichiometric compound TiO2-xNx on the composite film. The UV-Vis spectra of the film suggested that the visible light with wavelength of 550 nm could be absorbed for the N-doped composite film after EF&H treatment in comparison to a cutoff wavelength of 400 nm for the composite film without EF treatment. Photocatalytic experiments showed that the degradation rate of methylene blue by N-doped composite films increased significantly under visible light irradiation. The partial replacement of O by doped N played a very important role in narrowing the band gap and improving the visible light photocatalytic reactivity.

  12. Nanostructured Er3+-doped SiO2-TiO2 and SiO2-TiO2-Al2O3 sol-gel thin films for integrated optics

    Science.gov (United States)

    Predoana, Luminita; Preda, Silviu; Anastasescu, Mihai; Stoica, Mihai; Voicescu, Mariana; Munteanu, Cornel; Tomescu, Roxana; Cristea, Dana

    2015-08-01

    The nanostructured multilayer silica-titania or silica-titania-alumina films doped with Er3+ were prepared by sol-gel method. The sol-gel method is a flexible and convenient way to prepare oxide films on several types of substrates, and for this reason it was extensively investigated for optical waveguides fabrication. The selected molar composition was 90%SiO2-10%TiO2 or 85%SiO2-10%TiO2-5% Al2O3 and 0.5% Er2O3. The films were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Spectroellipsometry (SE), as well as by Atomic Force Microscopy (AFM) and photoluminescence (PL). The films deposited on Si/SiO2 substrate by dip-coating or spin-coating, followed by annealing at 900 °C, presented homogenous and continuous surface and good adherence to the substrate. Differences were noticed in the structure and properties of the prepared films, depending on the composition and the number of deposited layers. Channel optical waveguides were obtained by patterning Er3+-doped SiO2-TiO2 and SiO2-TiO2-Al2O3 sol-gel layers deposited on oxidized silicon wafers.

  13. Efficient planar n-i-p type heterojunction flexible perovskite solar cells with sputtered TiO2 electron transporting layers.

    Science.gov (United States)

    Mali, Sawanta S; Hong, Chang Kook; Inamdar, A I; Im, Hyunsik; Shim, Sang Eun

    2017-03-02

    The development of hybrid organo-lead trihalide perovskite solar cells (PSCs) comprising an electron transporting layer (ETL), a perovskite light absorber and a hole transporting layer (HTL) has received significant attention for their potential in efficient PSCs. However, the preparation of a compact and uniform ETL and the formation of a uniform light absorber layer suffer from a high temperature processing treatment and the formation of unwanted perovskite islands, respectively. A low temperature/room temperature processed ETL is one of the best options for the fabrication of flexible PSCs. In the present work, we report the implementation of a room temperature processed compact TiO2 ETL and the synthesis of extremely uniform flexible planar PSCs based on methylammonium lead mixed halides MAPb(I1-xBrx)3 (x = 0.1) via RF-magnetron sputtering and a toluene dripping treatment, respectively. The compact TiO2 ETLs with different thicknesses (30 to 100 nm) were directly deposited on a flexible PET coated ITO substrate by varying the RF-sputtering time and used for the fabrication of flexible PSCs. The photovoltaic properties revealed that flexible PSC performance is strongly dependent on the TiO2 ETL thickness. The open circuit voltage (VOC) and fill factor (FF) are directly proportional to the TiO2 ETL thickness while the 50 nm thick TiO2 ETL shows the highest current density (JSC) of 20.77 mA cm(-2). Our controlled results reveal that the room temperature RF-magnetron sputtered 50 nm-thick TiO2 ETL photoelectrode exhibits a power conversion efficiency (PCE) in excess of 15%. The use of room temperature synthesis of the compact TiO2 ETL by RF magnetron sputtering results in an enhancement of the device performance for cells prepared on flexible substrates. The champion flexible planar PSC based on this architecture exhibited a promising power conversion efficiency as high as 15.88%, featuring a high FF of 0.69 and VOC of 1.108 V with a negligible hysteresis under AM

  14. Vertical TiO2 Nanorods as a Medium for Stable and High-Efficiency Perovskite Solar Modules.

    Science.gov (United States)

    Fakharuddin, Azhar; Di Giacomo, Francesco; Palma, Alessandro L; Matteocci, Fabio; Ahmed, Irfan; Razza, Stefano; D'Epifanio, Alessandra; Licoccia, Silvia; Ismail, Jamil; Di Carlo, Aldo; Brown, Thomas M; Jose, Rajan

    2015-08-25

    Perovskite solar cells employing CH3NH3PbI3-xClx active layers show power conversion efficiency (PCE) as high as 20% in single cells and 13% in large area modules. However, their operational stability has often been limited due to degradation of the CH3NH3PbI3-xClx active layer. Here, we report a perovskite solar module (PSM, best and av. PCE 10.5 and 8.1%), employing solution-grown TiO2 nanorods (NRs) as the electron transport layer, which showed an increase in performance (∼5%) even after shelf-life investigation for 2500 h. A crucial issue on the module fabrication was the patterning of the TiO2 NRs, which was solved by interfacial engineering during the growth process and using an optimized laser pulse for patterning. A shelf-life comparison with PSMs built on TiO2 nanoparticles (NPs, best and av. PCE 7.9 and 5.5%) of similar thickness and on a compact TiO2 layer (CL, best and av. PCE 5.8 and 4.9%) shows, in contrast to that observed for NR PSMs, that PCE in NPs and CL PSMs dropped by ∼50 and ∼90%, respectively. This is due to the fact that the CH3NH3PbI3-xClx active layer shows superior phase stability when incorporated in devices with TiO2 NR scaffolds.

  15. Development of Dye-Sensitized Solar Cells with Sputtered N-Doped TiO2 Thin Films: From Modeling the Growth Mechanism of the Films to Fabrication of the Solar Cells

    Directory of Open Access Journals (Sweden)

    D. A. Duarte

    2014-01-01

    Full Text Available In this paper, nitrogen-doped TiO2 thin films were deposited by DC reactive sputtering at different doping levels for the development of dye-sensitized solar cells. The mechanism of film growth during the sputtering process and the effect of the nitrogen doping on the structural, optical, morphological, chemical, and electronic properties of the TiO2 were investigated by numerical modeling and experimental methods. The influence of the nitrogen doping on the working principle of the prototypes was investigated by current-voltage relations measured under illuminated and dark conditions. The results indicate that, during the film deposition, the control of the oxidation processes of the nitride layers plays a fundamental role for an effective incorporation of substitutional nitrogen in the film structure and cells built with nitrogen-doped TiO2 have higher short-circuit photocurrent in relation to that obtained with conventional DSSCs. On the other hand, DSSCs built with nondoped TiO2 have higher open-circuit voltage. These experimental observations indicate that the incorporation of nitrogen in the TiO2 lattice increases simultaneously the processes of generation and destruction of electric current.

  16. A Selective Ultrahigh Responding High Temperature Ethanol Sensor Using TiO2 Nanoparticles

    Directory of Open Access Journals (Sweden)

    M. M. Arafat

    2014-07-01

    Full Text Available In this research work, the sensitivity of TiO2 nanoparticles towards C2H5OH, H2 and CH4 gases was investigated. The morphology and phase content of the particles was preserved during sensing tests by prior heat treatment of the samples at temperatures as high as 750 °C and 1000 °C. Field emission scanning electron microscopy (FESEM, transmission electron microscopy (TEM and X-ray diffraction (XRD analysis were employed to characterize the size, morphology and phase content of the particles. For sensor fabrication, a film of TiO2 was printed on a Au interdigitated alumina substrate. The sensing temperature was varied from 450 °C to 650 °C with varying concentrations of target gases. Results show that the sensor has ultrahigh response towards ethanol (C2H5OH compared to hydrogen (H2 and methane (CH4. The optimum sensing temperature was found to be 600 °C. The response and recovery times of the sensor are 3 min and 15 min, respectively, for 20 ppm C2H5OH at the optimum operating temperature of 600 °C. It is proposed that the catalytic action of TiO2 with C2H5OH is the reason for the ultrahigh response of the sensor.

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

    Science.gov (United States)

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

    2014-10-01

    TiO2 nanorod arrays (TiO2 NRAs) sensitized with CdS nanoparticles were fabricated via successive ion layer adsorption and reaction (SILAR), and TiO2 NRAs were obtained by oxidizing Ti NRAs obtained through oblique angle deposition. The TiO2 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 TiO2 NRAs. This provides a promising way to fabricate the material for solar energy conversion and wastewater degradation.

  18. Hierarchical structured TiO2 photoanodes for dye-sensitized solar cells.

    Science.gov (United States)

    Shih, Yen-Chen; Chu, Ann-Kuo; Huang, Wen-Yao

    2012-04-01

    A novel approach has been developed to fabricate hills-like hierarchical structured TiO2 photoanodes for dye-sensitized solar cells (DSSCs). The appropriately aggregated TiO2 clusters in the photoanode layer could cause stronger light scattering and higher dye loading that increases the efficiency of photovoltaic device. For detailed light-harvesting study, different molecular weights of polyvinyl alcohol (PVA) were used as binders for TiO2 nanoparticles (P-25 Degussa) aggregation. A series of TiO2 films with dissimilar morphology, the reflection of TiO2 films, absorbance of attached dye, amount of dye loading, and performance of fabricated DSSC devices, were measured and investigated. An optimized device had energy conversion efficiency of 4.47% having a higher dye loading and good light harvesting, achieving a 23% increase of short-circuit current J(sc) in DSSCs.

  19. Surface morphology of titanium dioxide (TiO2) nanoparticles on aluminum interdigitated device electrodes (IDEs)

    Science.gov (United States)

    Azizah, N.; Hashim, U.; Arshad, M. K. Md.; Gopinath, Subash C. B.; Nadzirah, Sh.; Farehanim, M. A.; Fatin, M. F.; Ruslinda, A. R.; Ayub, R. M.

    2016-07-01

    Titanium dioxide (TiO2) nanoparticles based Interdigitated Device Electrodes (IDEs) Nanobiosensor device was developed for intracellular biochemical detection. Fabrication and characterization of Scanning Electron Microscopy (SEM) using IDE nanocoated with TiO2 was studied in this paper. SEM analysis was carried out at 10 kV acceleration volatege and a 9.8 mA emission current to compare IDE with and without TiO2 on the surface area. The simple fabrication process, high sensitivity, and fast response of the TiO2 based IDEs facilitate their applications in a wide range of areas. The small size of semiconductor TiO2 based IDE for sensitive, label-free, real time detection of a wide range of biological species could be explored in vivo diagnostics and array-based screening.

  20. Enhancement of Photocatalytic Activity on TiO2-Nitrogen-Doped Carbon Nanotubes Nanocomposites

    OpenAIRE

    Lingling Wang; Long Shen; Yihuai Li; Luping Zhu; Jiaowen Shen; Lijun Wang

    2013-01-01

    TiO2-nitrogen-doped carbon nanotubes (TiO2-CNx) nanocomposites are successfully synthesized via a facile hydrothermal method. The prepared photocatalysts were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric and differential scanning calorimetry analyses (TGA-DSC). The results show that the TiO2 nanoparticles with a narrow size of 7 nm are uniformly deposited on CNx. The photocatalytic ac...

  1. The comparison of photocatalytic activity of synthesized TiO 2 and ZrO 2 nanosize onto wool fibers

    Science.gov (United States)

    Moafi, Hadi Fallah; Shojaie, Abdollah Fallah; Zanjanchi, Mohammad Ali

    2010-04-01

    TiO 2 and ZrO 2 nanocrystals were successfully synthesized and deposited onto wool fibers using the sol-gel technique at low temperature. The photocatalytic activities of TiO 2-coated and ZrO 2-coated wool fibers were measured by studying photodegradation of methylene blue and eosin yellowish dyes. The initial and the treated samples were characterized by several techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS) and X-ray diffraction. The TEM study shows dispersed particles with 10-30 nm in size for TiO 2-coated and 20-40 nm in size for ZrO 2-coated samples on the fiber surface. Comparison of the photocatalytic activity of the coated samples reveals superiority of TiO 2 modified sample with respect to that of ZrO 2 for degradation of both dyes. Our observations indicate that by applying this technique to the fabrics, self-cleaning materials could be designed for practical application.

  2. Bilayer hollow/spindle-like anatase TiO2 photoanode for high efficiency dye-sensitized solar cells

    Science.gov (United States)

    Wang, Guanxi; Zhu, Xunjin; Yu, Jiaguo

    2015-03-01

    Derived from a hollow TiO2 nanoparticle (HNP) as underlayer and a TiO2 spindle (SP) as light scattering overlayer, a new bilayer single-crystalline photoanode (HNP/SP) is fabricated for dye-sensitized solar cell (DSSC) application. The prepared bilayer TiO2 photoanode and two comparative HNP/HNP and SP/SP ones are fully characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV-vis absorption spectroscopy and N2 adsorption-desorption isotherms. An overall photoelectric conversion efficiency of 8.65% has been achieved for HNP/SP DSSC, which is 25% higher than that of HNP/HNP DSSC, and also far superior to that of SP/SP or conventional P25 DSSC. The improved photovoltaic performance of HNP/SP DSSC is attributed to the synergic effects, i.e. the single-crystalline bilayer structure favoring for rapid interfacial electron transport, the relatively large specific surface area of HNP for effective dye adsorption, and the 1D geometry of single-crystalline TiO2 spindles for direct electron transport pathway and strong light scattering effect.

  3. Structure of Hydrated Zn2+ at the Rutile TiO2 (110)-Aqueous Solution Interface: Comparsion of X-ray Standing Wave, X-ray Absorption Spectroscopy, and Density Functional Theory Results

    Energy Technology Data Exchange (ETDEWEB)

    Zhang,Z.; Fenter, P.; Kelly, S.; Catalano, J.; Bandura, A.; Kubicki, J.; Sofo, J.; Wesolowski, D.; Machesky, M.; et al.

    2006-01-01

    Adsorption of Zn{sup 2+} at the rutile TiO2 (110)-aqueous interface was studied with Bragg-reflection X-ray standing waves (XSW), polarization-dependent surface extended X-ray absorption fine structure (EXAFS) spectroscopy, and density functional theory (DFT) calculations to understand the interrelated issues of adsorption site, its occupancy, ion-oxygen coordination and hydrolysis. At pH 8, Zn{sup 2+} was found to adsorb as an inner-sphere complex at two different sites, i.e., monodentate above the bridging O site and bidentate between two neighboring terminal O sites. EXAFS results directly revealed a four or fivefold first shell coordination environment for adsorbed Zn{sup 2+} instead of the sixfold coordination found for aqueous species at this pH. DFT calculations confirmed the energetic stability of a lower coordination environment for the adsorbed species and revealed that the change to this coordination environment is correlated with the hydrolysis of adsorbed Zn{sup 2+}. In addition, the derived adsorption locations and the occupancy factors of both sites from three methods agree well, with some quantitative discrepancies in the minor site location among the XSW, EXAFS, and DFT methods. Additional XSW measurements showed that the adsorption sites of Zn{sup 2+} were unchanged at pH 6. However, the Zn{sup 2+} partitioning between the two sites changed substantially, with an almost equal distribution between the two types of sites at pH 6 compared to predominantly monodentate occupation at pH 8.

  4. Formation of rod-like nanostructure by aggregation of TiO2 nanoparticles with improved performances

    Indian Academy of Sciences (India)

    Weijuan Zhang; Wenkai Chang; Baozhen Cheng; Zenghe Li; Junhui Ji; Yang Zhao; Jun Nie

    2015-10-01

    To improve the performance of titanium dioxide (TiO2)-based devices, many efforts have been made to prepare nanostructures with composite of TiO2 nanoparticles and nanorods. In this work, a novel rod-like TiO2 nanostructure was obtained via a controllable hydrolysis process. Morphology and structure analysis showed that the rod-like nanostructure was a well-aligned aggregate of nearly spherical TiO2 nanoparticles. Rod-like TiO2 nanoparticle aggregates were fabricated on a primary TiO2 nanoparticle-based layer without the use of template, and formed a hierarchical TiO2 composite film together. The photocatalytic activity of the TiO2 film with rod-like nanoparticle aggregates was evaluated by the degradation of methylene blue. The antibacterial activity of fabricated hierarchical TiO2 film was assessed against Staphylococcus aureus. The photoelectrochemical property of this film as the photoanode in assemble dye-sensitized solar cell was also tested. Compared with randomly distributed nanoparticle-based TiO2 film, the hierarchical TiO2 film exhibited improved performance of photocatalysis, antibacterial activity and photoelectric conversion.

  5. Synthesis, characterization and photocatalytic activity of fluorine doped TiO2 nanoflakes synthesized using solid state reaction method.

    Science.gov (United States)

    Umadevi, M; Parimaladevi, R; Sangari, M

    2014-01-01

    Fluorine doped TiO2 were synthesized by solid state reaction method. Optical and structural properties of fluorine doped TiO2 were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, UV-vis diffusion reflectance spectroscopy and scanning electron microscopic techniques. The prepared fluorine doped TiO2 was smaller in size with respect to pure TiO2 and it is tetragonal in crystalline structure. Nanoflakes like structure of pure and fluorine doped TiO2 was confirmed from SEM image. Fluorine doped TiO2 shows smaller band gap, high strain and dislocation density when compared to pure TiO2. It also has higher photocatalytic activity with respect to pure TiO2.

  6. Study on Properties of Composite Oxides TiO2/SiO2

    Institute of Scientific and Technical Information of China (English)

    ZHOUYasong; JIANGGuowei

    2002-01-01

    The nanometer particles of TiO2 and TiO2/SiO2 oxides were prepared by sol-gel and supercritical fluid drying method.The properties of TiO2 and TiO2/SiO2 were characterized by means of BET(Brunner-Emmett-Teller method), TEM(transmission electron microscopy), SEM(Scanning electron microscopy), XRD(X-ray differaction) and FTIR(Fourier transform-infrared) techniques.The effects of different preparation route,prehydrolysis and non-prehydrolysis,on the properties of TiO2/SiO2 oxide were also examined.Experimental results show that the termal stability of pure TiO2 is improved greatly when it is mixed with SiO2 in nanometer level.The composite TiO2/SiO2 oxides form Ti-O-Si chemical bonds,which creates new Broensted acidity stes.The acidity character is related to TiO2/SiO2 chemical composition and preparation methods.The acidity of TiO2/SiO2 oxides by prehydrolysis is greater than that of by non-prehydrolysis.Ti atom is rich on the surface of TiO2/SiO2.

  7. 关于Diophantine方程(44n)x+(117n)y=(125n)z 的整数解%On the integral solutions of Diophantine equation (44n)x+(117n)y=(125n)z

    Institute of Scientific and Technical Information of China (English)

    鲁伟阳; 高丽; 郝虹斐

    2014-01-01

    在 Je´smanow´ıcz 猜想的基础上,利用初等方法证明了对任意的正整数 n, Diophantine方程(44n)x+(117n)y=(125n)z 仅有正整数解(x, y, z)=(2,2,2)。%In this paper, basing on Je´smanow´ıcz′ conjecture, it is proved that for any positive integral n the Diophantine equation (44n)x+(117n)y = (125n)z has only integral solution (x, y, z) = (2, 2, 2) by elementary method.

  8. 锐钛矿 TiO 2-Ag 纳米纤维的可控制备及光催化性能研究%Controllable synthesis of TiO2-Ag nanofibers from electrospinning for photocatalytic application

    Institute of Scientific and Technical Information of China (English)

    王翠娥; 叶海洋; 刘新华; 张广知; 王琪

    2015-01-01

    制备 TiO 2高效光催化试剂近年来备受关注.利用静电纺丝技术成功获得了尺寸均一的 TiO 2纳米纤维,在此基础上,以硝酸银(AgNO 3)为掺杂剂,合成了 TiO 2-Ag 复合纳米纤维.采用扫描电子显微镜(SEM)及X 射线衍射(XRD)对该复合材料进行了表征.结果显示,产物为锐钛矿 TiO 2-Ag 复合纳米纤维,且纤维分散性好、长径比大.随后以亚甲基蓝为降解对象,研究了该复合材料的光催化活性,探讨了 Ag 掺杂量对 TiO 2光催化效果的影响.结果表明:TiO 2-Ag 复合纳米纤维具有良好的光催化活性,且掺杂0.8 wt% Ag 的 TiO 2-Ag复合纳米纤维对亚甲基蓝的降解效率最高.%Great efforts have been made to prepare efficient TiO 2 photocatalysts in recent years.In this work,electrospinning technology was successfully employed to make one-dimensional TiO 2 .Meanwhile, the TiO 2 nanofibers doped with Ag nanoparticles were also fabricated based on this method.SEM and XRD are both used to characterize the hybrid nanofibers and the results show that these nanofibers are anatase TiO 2-Ag nanocomposites with desirable dispersion and good length to diameter ratio.Besides,the as-obtained TiO 2-Ag nanofibers exhibited excellent photocatalytic activity for the degradation of methyl-ene blue dye.

  9. Rapid sonosynthesis of N-doped nano TiO2 on wool fabric at low temperature: introducing self-cleaning, hydrophilicity, antibacterial/antifungal properties with low alkali solubility, yellowness and cytotoxicity.

    Science.gov (United States)

    Behzadnia, Amir; Montazer, Majid; Rashidi, Abousaeid; Mahmoudi Rad, Mahnaz

    2014-01-01

    Nano nitrogen-doped titanium dioxide was rapidly prepared by hydrolysis of titanium isopropoxide at 75-80°C using in situ sonochemical synthesis by introducing ammonia. Various concentrations of titanium isopropoxide were examined to deposit nano nitrogen-doped titanium dioxide through impregnation of the wool fabric in ultrasound bath followed by curing. The antibacterial/antifungal activities of wool samples were assessed against two common pathogenic bacteria including Escherichia coli and Staphylococcus aureus and the diploid fungus Candida albicans. The sonotreated wool fabrics indicated no adverse effects on human dermal fibroblasts. The presence of nanoparticles on the sonotreated wool fabrics were confirmed by FE-SEM images and EDS patterns and X-ray mapping and the crystalline size of nanoparticles were estimated through XRD results. The role of both pH and precursor concentration on the various properties of the fabric was investigated and the optimized conditions introduced using response surface methodology.

  10. Use of Anodic TiO2 Nanotube Layers as Mesoporous Scaffolds for Fabricating CH3NH3PbI3 Perovskite-based Solid State Solar Cells

    OpenAIRE

    Salazar, Raul; Altomare, Marco; Lee, Kiyoung; Tripathy, Jyotsna; Kirchgeorg, Robin; Nguyen, Nhat Truong; Mokhtar, Mohamed; Alshehri, Abdelmohsen; Al-Thabaiti, Shaeel A.; Schmuki, Patrik

    2016-01-01

    We optimize the deposition of CH3NH3PbI3 perovskite into mesoporous electrodes consisting of anodic TiO2 nanotube layers. By a simple spin coating approach, complete filling of the tube scaffolds is obtained, that leads to interdigitated perovskite structures in conformal contact with the TiO2 tube counterparts. Such assemblies can be used as solid state solar cells in hole-transporting material-free configuration, i.e., the tube scaffold serves as electron collector and blocking layer, while...

  11. Facile synthesis of superhydrophobic TiO2/polystyrene core-shell microspheres

    Directory of Open Access Journals (Sweden)

    2011-01-01

    Full Text Available In this paper, core-shell TiO2/polystyrene (TiO2/PS microspheres with superhydrophobic properties were prepared via a facile method. Our method needs neither special apparatus nor complicated chemical treatment. The whole process includes two steps: firstly, coupling agent was used to modify TiO2 by sol-gel method; secondly, fabrication of TiO2/PS dispersions was carried out via in-situ free-radical polymerization strategy. The component and structure of the TiO2/PS particles were characterized by Fourier transform infrared (FTIR spectroscopy, thermogravimetric analysis (TGA, field emission scanning electron microscope (FE-SEM and transmission electron microscopy (TEM. The TiO2 gel particles with average diameter of 1 μm exhibited irregular spherical shape and obvious aggregation. Compared with the TiO2 particles, the resulting TiO2/PS particulates showed regular spherical shape, better dispersion and bigger size. By directly depositing the resulted TiO2/PS dispersion on a Cu foil, the coating showed superhydrophobic property which was reflected by the contact angle (CA of water on the surface with high water adhesion. The apparent CA of water is 153.5±1.5°, suggesting that this composite possesses well superhydrophobicity.

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

    OpenAIRE

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

    2015-01-01

    A new titanium dioxide (TiO2) slurry formulation is herein reported for the fabrication of TiO2 photoanode for use in dye-sensitized solar cells (DSSCs). The prepared TiO2 photoanode featured a highly uniform mesoporous structure with well-dispersed TiO2 nanoparticles. The energy conversion efficiency of the resulting TiO2 slurry-based DSSC was ∼63% higher than that achieved by a DSSC prepared using a commercial TiO2 slurry. Subsequently, the incorporation of acid-treated multi-walled carbon ...

  13. Robust superamphiphobic film from electrospun TiO2 nanostructures.

    Science.gov (United States)

    Ganesh, V Anand; Dinachali, Saman Safari; Nair, A Sreekumaran; Ramakrishna, Seeram

    2013-03-13

    Rice-shaped TiO2 nanostructures are fabricated by electrospinning for creating a robust superamphiphobic coating on glass substrates. The as-fabricated TiO2 nanostructures (sintered at 500 °C) are superhydrophilic in nature which upon silanization turn into superamphiphobic surface with surface contact angle (SCA) values achieved using water (surface tension, γ = 72.1 mN/m) and hexadecane (surface tension, γ = 27.5 mN/m) being 166° and 138.5°, respectively. The contact angle hysteresis for the droplet of water and hexadecane are measured to be 2 and 12°, respectively. Thus, we have successfully fabricated superior self-cleaning coatings that possess exceptional superamphiphobic property by employing a simple, cost-effective, and scalable technique called electrospinning. Furthermore, the coating showed good mechanical and thermal stability with strong adherence to glass surface, thus revealing the potential for real applications.

  14. D-sorbitol-induced phase control of TiO2 nanoparticles and its application for dye-sensitized solar cells

    Science.gov (United States)

    Shaikh, Shoyebmohamad F.; Mane, Rajaram S.; Min, Byoung Koun; Hwang, Yun Jeong; Joo, Oh-Shim

    2016-02-01

    Using a simple hydrothermal synthesis, the crystal structure of TiO2 nanoparticles was controlled from rutile to anatase using a sugar alcohol, D-sorbitol. Adding small amounts of D-sorbitol to an aqueous TiCl4 solution resulted in changes in the crystal phase, particle size, and surface area by affecting the hydrolysis rate of TiCl4. These changes led to improvements of the solar-to-electrical power conversion efficiency (η) of dye-sensitized solar cells (DSSC) fabricated using these nanoparticles. A postulated reaction mechanism concerning the role of D-sorbitol in the formation of rutile and anatase was proposed. Fourier-transform infrared spectroscopy, 13C NMR spectroscopy, and dynamic light scattering analyses were used to better understand the interaction between the Ti precursor and D-sorbitol. The crystal phase and size of the synthesized TiO2 nanocrystallites as well as photovoltaic performance of the DSSC were examined using X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and photocurrent density-applied voltage spectroscopy measurement techniques. The DSSC fabricated using the anatase TiO2 nanoparticles synthesized in the presence of D-sorbitol, exhibited an enhanced η (6%, 1.5-fold improvement) compared with the device fabricated using the rutile TiO2 synthesized without D-sorbitol.

  15. Photocatalytic degradation of monoethanolamine in wastewater using nanosized TiO2 loaded on clinoptilolite

    Science.gov (United States)

    Khodadoust, Saeid; Sheini, Azarmidokht; Armand, Nezam

    2012-06-01

    The use of titanium dioxide (TiO2) as photocatalyst to degrade the organic compounds is an effective method of oxidation process and has been widely studied in environmental engineering. In this investigation photocatalytic degradation of monoethanolamine (MEA) using TiO2 (in form of anatase) loaded on surface of clinoptilolite (CP) (TiO2-CP) in wastewater was studied. The surface interaction between TiO2 and CP was investigated by means of transmission electron microscope (TEM), atom force microscope (AFM), IR and X-ray diffraction (XRD). Then the effects of some parameters such as pH, amount of photocatalyst, and initial concentration of MEA on degradation percentage of MEA were examined. The obtained results show that the TiO2-CP is an active photocatalyst as compared with TiO2 nanopowders. All these results indicated that this proposed method can be useful for the development of wastewater treatment applications.

  16. Microwave irradiation induced band gap tuning of MoS2-TiO2 nanocomposites

    Science.gov (United States)

    Shakya, Jyoti; Mohanty, T.

    2016-05-01

    The MoS2-TiO2 nanocomposites have been synthesized by sol-gel method and characterized by different microscopic and spectroscopic techniques. The crystallinity of these nanocomposites has been confirmed by X-ray diffraction (XRD) analysis. The Raman spectrum of MoS2-TiO2 nanocomposites consists of three distinct peaks (E1 g, E1 2g and A1g) which are associated with TiO2 and MoS2. The morphological study is carried out by scanning electron microscope. The effect of microwave irradiation on the band gap of MoS2-TiO2 nanocomposites has been investigated; it is observed that the microwave irradiation causes decrease in the band gap of MoS2-TiO2 nanocomposites. The microwave treated MoS2-TiO2 thin films offers a novel process route in treating thin films for commercial applications.

  17. Preparation and Photocatalytic Activity of TiO2/Fine Char for Removal of Rhodamine B

    Directory of Open Access Journals (Sweden)

    Mingjie Ma

    2015-01-01

    Full Text Available TiO2/fine char (FC photocatalyst was prepared via sol-gel method with tetrabutyl titanate as the precursor and FC as the carrier. The structural property of TiO2/FC photocatalyst was investigated by X-ray diffraction (XRD and scanning electron microscopy (SEM, and the photocatalytic activity of TiO2/FC was evaluated by photocatalytic degradation of rhodamine B (RhB aqueous solution under UV light irradiation. The results showed that TiO2 was successfully coated on the surface of FC, and the TiO2/FC photocatalyst had better photocatalytic efficiency and stability for degradation of RhB under UV light illumination as compared to that of the pure TiO2 and FC. The study provided a novel way for the application of FC to the photocatalytic degradation of organic wastes.

  18. Morphological structure and physicochemical properties of nanotube TiO2

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Morphological structure and physicochemical properties of nanotube TiO2 were investigated. It was found that the TiO2 nanotube consisted of 2-5 monolayers of TiO2 molecules, and its inner diameter was between 4.2 and 5.9 nm. The nanotube TiO2 powder had high specific surface area and pore volume (379 m2/g and 1.431 cm3/g respectively) and its decolorization activity for Reactive Brilliant Red X-3B was 2 times higher than that of raw TiO2 (p-25). This new type of TiO2 was hopeful for application in photocatalysis and composite nanomaterial.

  19. Synthesis and characterization of TiO2 and Ag/TiO2 nanostructure

    Science.gov (United States)

    Gahlot, Swati; Thakur, Amit Kumar; Kulshrestha, Vaibhav; Shahi, V. K.

    2013-02-01

    Single phase anatase TiO2 nanoparticles were prepared using Titanium tertachloride (TiCl4) as precursor through an inexpensive method. Well dispersed nanocomposites of silver at TiO2 were synthesized successfully by photochemical route. Both TiO2 and Ag/TiO2 were characterized using X-Ray Diffraction (XRD) and transmission electron microscopy (TEM). The particle size of TiO2 is found to be ˜ 11 nm and ˜ 22 nm for Ag/TiO2, by XRD and confirmed by TEM. TEM micrographs also show the single phase crystal of TiO2 and confirm the deposition of silver among TiO2.

  20. Effect of TiO2 nanotube length and lateral tubular spacing on photovoltaic properties of back illuminated dye sensitized solar cell

    Indian Academy of Sciences (India)

    Shantikumar V Nair; A Balakrishnan; K R V Subramanian; A M Anu; A M Asha; B Deepika

    2012-08-01

    The main objective of this study is to show the effect of TiO2 nanotube length, diameter and intertubular lateral spacings on the performance of back illuminated dye sensitized solar cells (DSSCs). The present study shows that processing short TiO2 nanotubes with good lateral spacings could significantly improve the performance of back illuminated DSSCs. Vertically aligned, uniform sized diameter TiO2 nanotube arrays of different tube lengths have been fabricated on Ti plates by a controlled anodization technique at different times of 24, 36, 48 and 72 h using ethylene glycol and ammonium fluoride as an electrolyte medium. Scanning electron microscopy (SEM) showed formation of nanotube arrays spread uniformly over a large area. X-ray diffraction (XRD) of TiO2 nanotube layer revealed the presence of crystalline anatase phases. By employing the TiO2 nanotube array anodized at 24 h showing a diameter ∼80 nm and length ∼1.5 m as the photo-anode for back illuminated DSSCs, a full-sun conversion efficiency () of 3.5%was achieved, the highest value reported for this length of nanotubes.

  1. Effects of TiO2 structures in dye-sensitized solar cell.

    Science.gov (United States)

    Kim, Bok-Min; Rho, Seon-Gyun; Kang, Choon-Hyoung

    2011-02-01

    In this work, the effects of crystalline structure of the TiO2, which is incorporated in fabrication of the n-type electrode, on the DSSC performance were investigated in terms of the energy conversion efficiency. In this effort, TiO2 nanoparticle pastes with varying contents of rutile and anatase structures were prepared by using the ethanol mixing method. The most efficient photo-electro-chemical performance was achieved for the DSSC fabricated with the TiO2 paste in which the anatase form of the nanocrystal extends to 90%.

  2. A facile hydrothermal approach for construction of carbon coating on TiO2 nanoparticles

    OpenAIRE

    Olurode, Kehinde; Neelgund, Gururaj M.; Oki, Aderemi; Luo, Zhiphing

    2011-01-01

    Herein a facile hydrothermal approach is used to construct carbon coated TiO2 nanoparticles employing dextrose as the source of carbon. The procedure is operated at a low temperature of 200 °C. Fourier infrared spectroscopy demonstrated the successful coating of carbon on TiO2 nanoparticles. The phase composition of TiO2 and carbon coated TiO2 nanoparticles were studied using X-ray diffraction and the surface morphology was analyzed by scanning and transmission electron microscopy. The existe...

  3. Preparation and Photocatalysis of Mesoporous TiO2 Nanofibers via an Electrospinning Technique

    Institute of Scientific and Technical Information of China (English)

    WANG Wei; YUAN Qing; CHI Yue; SHAO Chang-lu; LI Nan; LI Xiao-tian

    2012-01-01

    Mesoporous TiO2 nanofibers have been synthesized by a new method that combines sol-gel chemistry and electrospinning technique.The obtained mesoporous TiO2 nanofibers were characterized with scanning electron microscopy(SEM),X-ray diffraction(XRD),transmission electron microscopy(TEM) and nitrogen adsorptiondesorption isotherms.The photocatalytic performance was evaluated by the photocatalytic degradation of Rhodamine B undcr UV light irradiation.The results show that mesoporous TiO2 nanofibers exhibit higher photocatalytic activity compared with nonporous TiO2 nanofibers.

  4. Decolorization of Methylene Blue with TiO2 Sol via UV Irradiation Photocatalytic Degradation

    OpenAIRE

    2010-01-01

    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. Th...

  5. Optimization of Solar Photocatalytic Degradation of Chloroxylenol Using TiO2, Er3+/TiO2, and Ni2+/TiO2 via the Taguchi Orthogonal Array Technique

    OpenAIRE

    Ahmed J. Mohammed; Kadhum, Abdul Amir H.; Muneer M. Ba-Abbad; Ahmed A. Al-Amiery

    2016-01-01

    In this study, the optical properties of a TiO2 photocatalyst were enhanced with various impregnations of Er3+ and Ni2+ separately, using the impregnation method as photocatalysts for the direct solar photolysis degradation of chloroxylenol. The synthesized Er3+/TiO2 and Ni2+/TiO2 catalysts were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), metal mapping, and ultraviolet visible (UV–Vis) spectroscopy. The resul...

  6. Photocatalytic degradation of phenol by visible light-responsive iron-doped TiO2 and spontaneous sedimentation of the TiO2 particles.

    Science.gov (United States)

    Nahar, Mst Shamsun; Hasegawa, Kiyoshi; Kagaya, Shigehiro

    2006-12-01

    Fe-doped TiO2 was prepared by the calcination of Fe(x)TiS(2) (x=0, 0.002, 0.005, 0.008, 0.01) and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible diffuse reflectance spectra. All the Fe-doped TiO2 were composed of an anatase crystal form and showed red shifts to a longer wavelength. The activity of the Fe-doped TiO2 for the degradation of phenol was investigated by varying the iron content during UV (365nm) and visible light (405nm and 436nm) irradiation. The degradation rate depended on the Fe content and the Fe-doped TiO2 was responsive to the visible light as well as the elevated activity toward UV light. The molar ratio of 0.005 was the optimum for both the UV and visible light irradiations. The result was discussed on the basis of the balance of the excited electron-hole trap by the doped Fe(3+) and their charge recombination on the doped Fe(3+) level. The Fe-doped TiO2 (x=0.005) was more active than P25 TiO2 under solar light irradiation. The suspended Fe-doped TiO2 spontaneously precipitated once the stirring of the reaction mixture was terminated.

  7. Comparison of electrode structures and photovoltaic properties of porphyrin-sensitized solar cells with TiO2 and Nb, Ge, Zr-added TiO2 composite electrodes.

    Science.gov (United States)

    Imahori, Hiroshi; Hayashi, Shinya; Umeyama, Tomokazu; Eu, Seunghun; Oguro, Akane; Kang, Soonchul; Matano, Yoshihiro; Shishido, Tetsuya; Ngamsinlapasathian, Supachai; Yoshikawa, Susumu

    2006-12-19

    Electrode structures and photovoltaic properties of porphyrin-sensitized solar cells with TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were examined to disclose the effects of partial substitution of Ti atom by the other metals in the composite electrodes. The TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were prepared by sol-gel process using laurylamine hydrochloride as a template for the formation of micellar precursors yielding well-defined mesoporous nanocrystalline structures, as in the cases of the formation of silica and titania tubules and nanoparticles by the templating mechanism. The TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were characterized by transmission electron microscopy, BET surface area analysis, X-ray diffraction analysis, Raman spectroscopy, and impedance measurements. The TiO2 anatase nanocrystalline structure is retained after doping a small amount (5 mol %) of Nb, Ge, or Zr into the TiO2 structure, suggesting the homogeneous distribution of the doped metals with replacing Ti atom by the doped metal. The power conversion efficiency of the porphyrin-sensitized solar cells increases in the order Zr-added TiO2 (0.8%) TiO2 (1.2%) TiO2 (2.0%) TiO2 cells (2.4%) under the same conditions. The improvement of cell performance of the Ge-added TiO2 cell results from the negative shift of the conduction band of the Ge-added TiO2 electrode. The Ge-added TiO2 cell exhibited a maximum power conversion efficiency of 3.5% when the porphyrin was adsorbed onto the surface of the Ge-added TiO2 electrode with a thickness of 4 microm in MeOH for 1 h.

  8. Synthesis and characterization of Ag doped TiO2 heterojunction films and their photocatalytic performances

    Science.gov (United States)

    Demirci, Selim; Dikici, Tuncay; Yurddaskal, Metin; Gultekin, Serdar; Toparli, Mustafa; Celik, Erdal

    2016-12-01

    In this study, undoped and silver (Ag) doped titanium dioxide (TiO2) films were successfully synthesized by sol-gel spin coating technique on the Si substrates. Photocatalytic activities of the TiO2 films with different Ag content were investigated for the degradation of methylene blue (MB) under UV light irradiation. The crystal phase structure, surface morphology, chemical and optical properties of Ag-doped TiO2 films were characterized using an X-ray diffractometer (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-vis spectrophotometer, and FTIR spectrophotometer. The results showed that the Ag-doped TiO2 films calcined at 500 °C had the crystalline anatase phases and the surface morphologies with some cracks. Ag substitution into TiO2 matrix enhanced the photocatalytic activity of TiO2 films under UV light irradiation as compared to the undoped TiO2 film. Furthermore, the results indicated that the 0.7% Ag doped TiO2 film exhibited a superior photocatalytic activity than that of undoped and other Ag-doped TiO2 films. This study demonstrated the potential of an application of Ag doped films to efficiently treat dissolved organic contaminants in water.

  9. Copper modified TiO2 catalysts: application to nitrobenzenes degradation

    Directory of Open Access Journals (Sweden)

    Chunyu Shui

    2016-01-01

    Full Text Available Copper doped TiO2 by the method of sol-gel preparation was conducted to stimulate the TiO2 visible light response and enhance the performance of photocatalytic degradation. By XRD, SEM and EDS analysis, molar ratio of 1.0%, 1.5%, 2.0% and 1.0% Cu doped TiO2 presented smaller grain sizes (20-50 nm than German P25 TiO2 (50-100 nm. Especially, 1.5% Cu doped TiO2 presented the highest and finest degree of crystallinity from XRD peak. Its reunion phenomenon was the weakest among all Cu doped TiO2. Combined with Cu doping structure, micro stress changes as well as the performance of the degradation of nitrobenzenes (NBs, the optimum mol ratio of Cu doped TiO2 was 1.5%. With 1.5% Cu doped TiO2 for 180 min UV light degradation of NBs, the removal efficiency was 60.02%, two times higher than that of Germany P25 TiO2. The reaction of NBs photocatalytic degradation by CuxTi(1-xO2 followed first order kinetics. Synthetically, SEM, ESD and performances of NBs degradation confirmed that the optimal formula of CuxTi(1-xO2 for degradation of NBs was Cu0.0183Ti0.9817O2.

  10. Simple way to make Anatase TiO2 films on FTO glass for promising solar cells

    OpenAIRE

    Raghavender, A. T.; Samantilleke, A. P.; Sá,Pedro; Almeida, B. G.; Vasilevskiy, Mikhail; Nguyen Hoa Hong

    2011-01-01

    TiO2 is a wide bandgap semiconductor material used as the photo anode in dye sensitized solar cells (DSSC). The fabrication of TiO2 on conductive glass substrates plays an important role in the solar cell efficiency, since the thickness of the TiO2 coating affects the transmission, photoconductive properties and the efficiency of solar cells. The uncorrected transmission in our fabricated films is as high as 80%, and the bandgap obtained is similar to that of bulk anatase TiO2, co...

  11. Elastic Properties and the Band Gap of AlNxP1-x Semiconductor Alloy: A Comparative Study of Various Ab Initio Approaches

    Directory of Open Access Journals (Sweden)

    M. P. Polak

    2016-01-01

    Full Text Available Structural and elastic properties of AlNxP1-x, a novel semiconductor alloy, are studied from the first principles in both zinc-blende and wurtzite structures. Performances of the finite difference (FD method and the density functional perturbation theory (DFPT are tested and compared. Both of these methods are applied to two different approaches of alloy simulation, a supercell of 16 and 32 atoms (for zinc-blende and wurtzite structures, resp. and the alchemical mixing (AM method, where the pseudopotentials are mixed in an appropriate way to form an alloy. All elastic properties, including the elastic tensors, elastic moduli, Poisson’s ratio, B/G, and relaxation coefficient, as well as lattice parameters are calculated using all said methods. Conclusions about the use of the approaches investigated in this paper and about their performance are drawn. In addition, in both crystal structures, the band gap is studied in the whole composition range using the MBJLDA functional. The band gap bowings are unusually high, which confirms earlier reports.

  12. Electronic band structure and optical gain of GaNxBiyAs1-x-y/GaAs pyramidal quantum dots

    Science.gov (United States)

    Song, Zhi-Gang; Bose, Sumanta; Fan, Wei-Jun; Li, Shu-Shen

    2016-04-01

    The electronic band structure and optical gain of GaNxBiyAs1-x-y/GaAs pyramidal quantum dots (QDs) are investigated using the 16-band k ṡ p model with constant strain. The optical gain is calculated taking both homogeneous and inhomogeneous broadenings into consideration. The effective band gap falls as we increase the composition of nitrogen (N) and bismuth (Bi) and with an appropriate choice of composition we can tune the emission wavelength to span within 1.3 μm-1.55 μm, for device application in fiber technology. The extent of this red shift is more profound in QDs compared with bulk material due to quantum confinement. Other factors affecting the emission characteristics include virtual crystal, strain profile, band anticrossing (BAC), and valence band anticrossing (VBAC). The strain profile has a profound impact on the electronic structure, specially the valence band of QDs, which can be determined using the composition distribution of wave functions. All these factors eventually affect the optical gain spectrum. With an increase in QD size, we observe a red shift in the emission energy and emergence of secondary peaks owing to transitions or greater energy compared with the fundamental transition.

  13. Chemical beam epitaxy of GaAs1-xNx using MMHy and DMHy precursors, modeled by ab initio study of GaAs(100) surfaces stability over As2, H2 and N2

    Science.gov (United States)

    Valencia, Hubert; Kangawa, Yoshihiro; Kakimoto, Koichi

    2017-06-01

    Using ab initio calculations, a simple model for GaAs1-xNx vapor-phase epitaxy on (100) surface of GaAs was created. By studying As2 and H2 molecules adsorptions and As/N atom substitutions on (100) GaAs surfaces, we obtain a relative stability diagram of all stable surfaces under varying As2, H2, and N2 conditions. We previously proved that this model could describe the vapor-phase epitaxy of GaAs1-x Nx with simple, fully decomposed, precursors. In this paper, we show that in more complex reaction conditions using monomethylhydrazine (MMHy), and dimethylhydrazine (DMHy), it is still possible to use our model to obtain an accurate description of the temperature and pressure stability domains for each surfaces, linked to chemical beam epitaxy (CBE) growth conditions. Moreover, the different N-incorporation regimes observed experimentally at different temperature can be explain and predict by our model. The use of MMHy and DMHy precursors can also be rationalized. Our model should then help to better understand the conditions needed to obtain an high quality GaAs1-xNx using vapor-phase epitaxy.

  14. Photocatalytic Properties of TiO2 Porous Network Film.

    Science.gov (United States)

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

    2015-09-01

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

  15. Correlation between the band positions of (SrTiO3)1-x.(LaTiO2N)x solid solutions and photocatalytic properties under visible light irradiation.

    Science.gov (United States)

    Luo, Wenjun; Li, Zhaosheng; Jiang, Xiaojun; Yu, Tao; Liu, Lifei; Chen, Xinyi; Ye, Jinhua; Zou, Zhigang

    2008-11-28

    N-doped SrTiO3 and (SrTiO3)1-x.(LaTiO2N)x samples were prepared by the thermal ammonolysis method. The photocatalytic activities of the samples were investigated in a water suspension system. Aqueous methanol solution (50 mL CH3OH + 220 mL H2O) for H2 evolution and aqueous silver nitrate solution (270 mL, 0.01 mol L(-1)) for O2 evolution were used as sacrificial reagents. The oxynitrides showed photocatalytic activities under visible light irradiation. The maximum rates of photocatalytic hydrogen and oxygen evolution under visible light irradiation (lambda > 420 nm) were 10 and 8 micromol h(-1), respectively. The samples were characterized by X-ray diffractometry, UV-Vis spectrophotometry, Fourier transform infrared spectrometry, and laser Raman spectroscopy. The unit cell edge length of (SrTiO3)1-x.(LaTiO2N)x increased linearly and their band gaps reduced from 3.18 to 2.04 eV with increasing x from 0 to 0.30. Moreover, the calculation results of (SrTiO3)0.75.(LaTiO2N)0.25 by density functional theory suggested that the band gap narrowing of the solid solutions came from the hybridization of N2p and O2p orbital. The band positions of the solid solutions were further investigated by Mott-Schottky and the onset potential method. The results suggested that the conduction band of the solid solution was lowered, which led to decrement of the hydrogen evolution rate.

  16. New evidence for TiO2 uniform surfaces leading to complete bacterial reduction in the dark: critical issues.

    Science.gov (United States)

    Nesic, Jelena; Rtimi, Sami; Laub, Danièle; Roglic, Goran M; Pulgarin, Cesar; Kiwi, John

    2014-11-01

    This study presents new evidence for the events leading to Escherichia coli reduction in the absence of light irradiation on TiO2-polyester (from now on TiO2-PES. By transmission electron microscopy (TEM) the diffusion of TiO2 NP's aggregates with the E. coli outer lipo-polyssacharide (LPS) layer is shown to be a prerequisite for the loss of bacterial cultivability. Within 30 min in the dark the TiO2 aggregates interact with E. coli cell wall leading within 120 min to the complete loss of bacterial cultivability on a TiO2-PES 5% TiO2 sample. The bacterial reduction was observed to increase with a higher TiO2 loading on the PES up to 5%. Bacterial disinfection on TiO2-PES in the dark was slower compared to the runs under low intensity simulated sunlight light irradiation. The interaction between the TiO2 aggregates and the E. coli cell wall is discussed in terms of the competition between the TiO2 units collapsing to form TiO2-aggregates at a physiologic pH-value followed by the electrostatic interaction with the bacteria surface. TiO2-PES samples were able to carry repetitive bacterial inactivation. This presents a potential for practical applications. X-ray photoelectron spectroscopy (XPS) evidence was found for the reduction of Ti4+ to Ti3+ contributing to redox interactions between TiO2-PES and the bacterial cell wall. Insight is provided into the mechanism of interaction between the E. coli cell wall and TiO2 NP's. The properties of the TiO2-PES surface like percentage atomic concentration, TiO2-loading, optical absorption, surface charge and crystallographic phases are reported in this study.

  17. PHOTOCATALYTIC ACTIVITY OF LANTHANUM DOPING TiO2

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The photocatalytic activity of the mixtures of TiO2 with the rare earth oxide La was investigated. The study on the effect of the rare earth oxide content, calcinating temperature and calcinating time on the performance of the mixture revealed that sample treated under higher temperature and longer time had higher photoactivity than pure TiO2. The experimental results of polycrystalline X-ray diffraction showed that the extent of the lattice expansion varied with the variation of calcinating temperature or time. It is suggested that this might be due to the variation of La content diffused into the TiO2 lattice. The La in the lattice may inhibit the recombinatin of photogenerated electron-hole pairs and thus enhance the photoactivity.

  18. Dry-spray deposition of TiO2 for a flexible dye-sensitized solar cell (DSSC) using a nanoparticle deposition system (NPDS).

    Science.gov (United States)

    Kim, Min-Saeng; Chun, Doo-Man; Choi, Jung-Oh; Lee, Jong-Cheon; Kim, Yang Hee; Kim, Kwang-Su; Lee, Caroline Sunyong; Ahn, Sung-Hoon

    2012-04-01

    TiO2 powders were deposited on indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrates for application to the photoelectrode of a dye-sensitized solar cell (DSSC). In the conventional DSSC manufacturing process, a semiconductor oxide such as TiO2 powder requires a sintering process at higher temperature than the glass transition temperature (T(g)) of polymers, and thus utilization of flexible polymer substrates in DSSC research has been constrained. To overcome this restriction related to sintering, we used a nanoparticle deposition system (NPDS) that could produce a thin coating layer through a dry-spray method under atmospheric pressure at room temperature. The powder was sprayed through a slit-type nozzle having a 0.4 x 10 mm2 rectangular outlet. In order to determine the deposited TiO2 thickness, five kinds of TiO2 layered specimens were prepared, where the specimens have single and double layer structures. Deposited powders on the ITO coated PET substrates were observed using FE-SEM and a scan profiler The thicker TiO2 photoelectrode with a DSSC having a double layer structure showed higher energy efficiency than the single layer case. The highest fabricated flexible DSSC displayed a short circuit current density J(sc) = 1.99 mA cm(-2), open circuit voltage V(oc) = 0.71 V, and energy efficiency eta = 0.94%. These results demonstrate the possibility of utilizing the dry-spray method to fabricate a TiO2 layer on flexible polymer substrates at room temperature under atmospheric pressure.

  19. Recombination reduction on lead halide perovskite solar cells based on low temperature synthesized hierarchical TiO2 nanorods

    Science.gov (United States)

    Jaramillo-Quintero, Oscar A.; Solís de La Fuente, Mauricio; Sanchez, Rafael S.; Recalde, Ileana B.; Juarez-Perez, Emilio J.; Rincón, Marina E.; Mora-Seró, Iván

    2016-03-01

    Intensive research on the electron transport material (ETM) has been pursued to improve the efficiency of perovskite solar cells (PSCs) and decrease their cost. More importantly, the role of the ETM layer is not yet fully understood, and research on new device architectures is still needed. Here, we report the use of three-dimensional (3D) TiO2 with a hierarchical architecture based on rutile nanorods (NR) as photoanode material for PSCs. The proposed hierarchical nanorod (HNR) films were synthesized by a two-step low temperature (180 °C) hydrothermal method, and consist of TiO2 nanorod trunks with optimal lengths of 540 nm and TiO2 nanobranches with lengths of 45 nm. Different device configurations were fabricated with TiO2 structures (compact layer, NR and HNR) and CH3NH3PbI3, using different synthetic routes, as the active material. PSCs based on HNR-CH3NH3PbI3 achieved the highest power conversion efficiency compared to PSCs with other TiO2 structures. This result can be ascribed mainly to lower charge recombination as determined by impedance spectroscopy. Furthermore, we have observed that the CH3NH3PbI3 perovskite deposited by the two-step route shows higher efficiency, surface coverage and infiltration within the structure of 3D HNR than the one-step CH3NH3PbI3-xClx perovskite.Intensive research on the electron transport material (ETM) has been pursued to improve the efficiency of perovskite solar cells (PSCs) and decrease their cost. More importantly, the role of the ETM layer is not yet fully understood, and research on new device architectures is still needed. Here, we report the use of three-dimensional (3D) TiO2 with a hierarchical architecture based on rutile nanorods (NR) as photoanode material for PSCs. The proposed hierarchical nanorod (HNR) films were synthesized by a two-step low temperature (180 °C) hydrothermal method, and consist of TiO2 nanorod trunks with optimal lengths of 540 nm and TiO2 nanobranches with lengths of 45 nm. Different

  20. Grain Size and Wettability of TiO2/SiO2 Photocatalytic Composite Thin Films

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The uniform transparent TiO2/SiO2 photocatalytic composite thin films are prepared by sol-gel method on the soda lime glass substrates, and characterized by UV-visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), BET surface area, FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that the addition of SiO2 to TiO2 thin films can suppress the grain growth of TiO2 crystal, increase the hydroxyl content on the surface of TiO2 films, lower the contact angle for water on TiO2 films and enhance the hydrophilic property of TiO2 films. The super-hydrophilic TiO2/SiO2 photocatalytic composite thin films with the contact angle of 0-° are obtained by the addition of 10%-20% SiO2 in mole fraction.

  1. Spinodal equation of state for rutile TiO2

    DEFF Research Database (Denmark)

    Francisco, E.; Bermejo, M.; Baonza, V. Garcia

    2003-01-01

    )-temperature (T) data of the rutile phase of TiO2. We show that results of ab initio perturbed ion calculations and very recent x-ray-diffraction experiments of isothermal compression on this system closely follow the spinodal conduct. The computational scheme permits the incorporation of temperature effects...

  2. 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.

  3. Structural and photocatalytic studies of Mn doped TiO2 nanoparticles.

    Science.gov (United States)

    Chauhan, Ruby; Kumar, Ashavani; Chaudhary, Ram Pal

    2012-12-01

    Mn-doped TiO(2) nanoparticles (Ti(1-)(x)Mn(x)O(2); where x=0.00-0.10) were synthesized by sol-gel method. The synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and UV-Vis spectrometer. The SEM and TEM micrographs revealed the agglomerated spherical-like morphology and measurements show that the size of crystallites is in the range of 10-20 nm. Optical measurements indicated a red shift in the absorption band edge after Mn doping. Direct allowed band gap of undoped and Mn-doped TiO(2) nanoparticles measured by UV-Vis spectrometer were 3.00 and 2.95 eV at 300 °C, respectively. Photocatalytic activities of TiO(2) and Mn doped TiO(2) were evaluated by irradiating the sample solution of methylene blue (MB) dye under ultraviolet and visible light exposure. It was found that Mn-doped TiO(2) bleaches MB much faster than undoped TiO(2) upon its exposure to the visible light as comparison to ultraviolet light. The experiment demonstrated that the photodegradation efficiency of Mn-doped TiO(2) was significantly higher than that of undoped TiO(2) upon its exposure to visible light.

  4. On the diophantine equation (91n)x + (4 140n)y =(4 141n)z%关于Diophantine方程(91n)x+(4140n)y=(4141n)z

    Institute of Scientific and Technical Information of China (English)

    鲁伟阳; 高丽; 王曦浛; 郝虹斐

    2015-01-01

    1956年Je(s)manowícz猜测Diophantine方程(na)x+(nb)y=(nc)z仅有正整数解(x,y,z)=(2,2,2),其中a,b,c是两两互素的正整数且满足a2+b2=c2.利用初等方法证明了对任意的正整数n,当a=7·13,b=22·32·5·23,c=41· 101时,Jesmanowícz猜想成立.

  5. Interstitial Boron-Doped TiO2 Thin Films: The Significant Effect of Boron on TiO2 Coatings Grown by Atmospheric Pressure Chemical Vapor Deposition.

    Science.gov (United States)

    Quesada-González, Miguel; Boscher, Nicolas D; Carmalt, Claire J; Parkin, Ivan P

    2016-09-28

    The work presented here describes the preparation of transparent interstitial boron-doped TiO2 thin-films by atmospheric pressure chemical vapor deposition (APCVD). The interstitial boron-doping, on TiO2, proved by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), is shown to enhance the crystallinity and significantly improve the photocatalytic activity of the TiO2 films. The synthesis, highly suitable for a reel-to-reel process, has been carried out in one step.

  6. Dynamics of fibronectin adsorption on TiO2 surfaces.

    Science.gov (United States)

    Sousa, S R; Brás, M Manuela; Moradas-Ferreira, P; Barbosa, M A

    2007-06-19

    In the present work we analyze the dynamics of fibronectin (FN) adsorption on two different stable titanium oxides, with varied surface roughness, and chemically similar to those used in clinical practice. The two types of titanium oxide surfaces used were TiO2 sputtered on Si (TiO2 sp) and TiO2 formed on commercially pure titanium after immersion in H2O2 (TiO2 cp). Surface characterization was previously carried out using different techniques (Sousa, S. R.; Moradas-Ferreira, P.; Melo, L. V.; Saramago, B.; Barbosa, M. A. Langmuir 2004, 20 (22), 9745-9754). Imaging and roughness analysis before and after FN adsorption used atomic force microscopy (AFM) in tapping mode, in air, and in magnetic alternating current mode, in liquid (water). FN adsorption as a function of time was followed by X-ray photoelectron spectroscopy (XPS), by radiolabeling of FN with 125I (125I-FN), and by ellipsometry. Exchangeability studies were performed using FN and HSA. AFM roughness analysis revealed that, before FN adsorption, both TiO2 surfaces exhibited a lower root-mean-square (Rq) and maximum peak with the depth of the maximum valley (Rmax) roughness in air than in water, due to TiO2 hydration. After protein adsorption, the same behavior was observed for the TiO2 sp substrate, while Rq and Rmax roughness values in air and in water were similar in the case of the TiO2 cp substrate, for the higher FN concentration used. Surface roughness was always significantly higher on the TiO2 cp surfaces. AFM led to direct visualization of adsorbed FN on both surfaces tested, indicating that after 10 min of FN incubation the TiO2 sp surface was partially covered by FN. The adsorbed protein seems to form globular aggregates or ellipsoids, and FN aggregates coalesce, forming clusters as the time of adsorption and the concentration increase. Radiolabeling of FN revealed that a rapid adsorption occurs on both surfaces and the amount adsorbed increased with time, reaching a maximum after 60 min of

  7. Characterization of ALD Processed Gallium Doped TiO2 Hole Blocking Layer in an Inverted Organic Solar Cell

    Science.gov (United States)

    Lee, Eun Ju; Ryu, Sang Ouk

    2016-10-01

    To improve power conversion efficiency (PCE) of inverted structure organic solar cells a buffer layer, a hole blocking layer (HBL) was introduced between cathode and active photovoltaic layer. Gallium (Ga) doped TiO2 as a HBL was fabricated by means of atomic layer deposition. X-ray photoelectron spectroscopy showed the highest Ga-Ti complex binding characteristics was achieved at 5% doping concentration. Gallium doped TiO2 layer exhibited over 94% of optical transmittance at the process temperature of 200°C. The resulting PCE of inverted structure organic solar cell having 5% doping in the hole block layer was 2.7%. The PCE was improved 35% compared to the cell without gallium doping.

  8. Characterization of ALD Processed Gallium Doped TiO2 Hole Blocking Layer in an Inverted Organic Solar Cell

    Science.gov (United States)

    Lee, Eun Ju; Ryu, Sang Ouk

    2017-02-01

    To improve power conversion efficiency (PCE) of inverted structure organic solar cells a buffer layer, a hole blocking layer (HBL) was introduced between cathode and active photovoltaic layer. Gallium (Ga) doped TiO2 as a HBL was fabricated by means of atomic layer deposition. X-ray photoelectron spectroscopy showed the highest Ga-Ti complex binding characteristics was achieved at 5% doping concentration. Gallium doped TiO2 layer exhibited over 94% of optical transmittance at the process temperature of 200°C. The resulting PCE of inverted structure organic solar cell having 5% doping in the hole block layer was 2.7%. The PCE was improved 35% compared to the cell without gallium doping.

  9. Nanofabrication of organic/inorganic hybrids of TiO2 with substituted phthalocyanine or polythiophene.

    Science.gov (United States)

    Ding, H; Ram, M K; Nicolini, C

    2001-06-01

    Organic photovoltaic cells, similar to Grätzel type, have been widely investigated in recent years. In the case of Grätzel-type cells, TiO2 colloids are usually spin-coated onto an electrode and then sintered. Later, such electrodes are immersed in dye solution to sensitize the TiO2 layer for fabrication of photovoltaic cells. In the current study, an attempt was made to fabricate photovoltaic cells using a layer-by-layer technique. Based on such a method, ordered substituted phthalocyanine or conducting polythiophene-sensitized TiO2 multilayers were fabricated at the molecular level. Buildup of multilayer films of copper phthalocyanine-capped TiO2 and poly(thiophene-3-acetic acid)/TiO2 was monitored by increments in the UV-visible absorption and the frequency decrease of quartz crystal microbalance. The ordered multilayers were further characterized by infrared spectroscopy, and electrochemical and photoelectrochemical measurements.

  10. Effects of Composition of ZnO Ceramics Containing TiO2 on Varistor Properties

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The development of low-voltage ZnO varistor ceramics containing TiO2 is presented in this report.The varistor properties of ZnO ceramics with different compositions were measured,and microstructure of the ceramics was investigated by XRD and SEM.The results show that the addition of TiO2 is beneficial to the decrease of varistor voltage (V1mA),whereas it leads to the recession of nonlinear coefficient (α) and leakage current (IL).The varistor properties of ZnO ceramics containing TiO2 can be effectively improved by introducing moderate amount of pre-fabricated ZnO seed grains.The behaviors of TiO2 and seed grains,as well as the mechanisms by which TiO2 and seed grains influence varistor properties,are discussed.

  11. Hydrogen Sensing with Ni-Doped TiO2 Nanotubes

    Directory of Open Access Journals (Sweden)

    Congqin Ning

    2013-07-01

    Full Text Available Doping with other elements is one of the efficient ways to modify the physical and chemical properties of TiO2 nanomaterials. In the present work, Ni-doped TiO2 nanotubes were fabricated through anodic oxidation of NiTi alloy and further annealing treatment. The hydrogen sensing properties of the nanotube sensor were investigated. It was found that the Ni-doped TiO2 nanotubes were sensitive to an atmosphere of 1,000 ppm hydrogen, showing a good response at both room temperature and elevated temperatures. A First-Principle simulation revealed that, in comparison with pure anatase TiO2 oxide, Ni doping in the TiO2 oxide could result in a decreased bandgap. When the oxide sensor adsorbed a certain amount of hydrogen the bandgap increased and the acceptor impurity levels was generated, which resulted in a change of the sensor resistance.

  12. 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.

  13. Structural, electronic, mechanical, thermal and optical properties of B(P,As)1-xNx; (x = 0, 0.25, 0.5, 0.75, 1) alloys and hardness of B(P,As) under compression using DFT calculations

    Science.gov (United States)

    Viswanathan, E.; Sundareswari, M.; Jayalakshmi, D. S.; Manjula, M.; Krishnaveni, S.

    2017-09-01

    First principles calculations are carried out in order to analyze the structural, electronic, mechanical, thermal and optical properties of BP and BAs compounds by ternary alloying with nitrogen namely B(P,As)1-xNx (x = 0.25, 0.5, 0.75) alloys at ambient condition. Thereby we report the mechanical and thermal properties of B(P,As)1-xNx (x = 0.25, 0.5, 0.75) alloys namely bulk modulus, shear modulus, Young's modulus, hardness, ductile-brittle nature, elastic wave velocity, Debye temperature, melting point, etc.; optical properties of B(P)1-xNx (x = 0.25, 0.5, 0.75) and B(As)1-xNx (x = 0.25, 0.75) alloys namely the dielectric function of real and imaginary part, refractive index, extinction coefficient and reflectivity and the hardness profile of the parent compounds BP and BAs under compression. The charge density plot, density of states histograms and band structures are plotted and discussed for all the ternary alloys of the present study. The calculated results agree very well with the available literature. Analysis of the present study reveals that the ternary alloy combinations namely BP.25N.75 and BAs.25N.75 could be superhard materials; hardness of BP and BAs increases with compression.

  14. Preparation and characterization of porous TiO2/ZnO composite nanofibers via electrospinning

    Institute of Scientific and Technical Information of China (English)

    Hai Ying Wang; Yang Yang; Xiang Li; Li Juan Li; Ce Wang

    2010-01-01

    Porous TiO2/ZnO composite nanofibers have been successfully prepared by electrospinning technique for the first time.It was generated by calcining TiO2/ZnCl2/PVP[PVP:poly(vinyi pyrrolidone)]nanofibers,which were electrospun from a mixture solution of TiO2,ZnCl2 and PVE Transmission electron microscopy(TEM)and X-ray diffraction(XRD)analyses were used to identify the morphology of the TiO2/ZnO nanofibers and a formation of inorganic TiO2/ZnO fibers.The porous structure of the TiO2/ZnO fbers was characterized by N2 adsoption/desorption isotherm.Surface photovoltage spectroscopy(SPS)and photo-catalytic activity measurements revealed advance properties of the porous TiO2/ZnO composite nanofibers and the results were compared with pure TiO2 nanofibers,pure ZnO nanofibers and TiO2/ZnO nanoparticles.

  15. Solar-driven photocatalytic treatment of diclofenac using immobilized TiO2-based zeolite composites.

    Science.gov (United States)

    Kovacic, Marin; Salaeh, Subhan; Kusic, Hrvoje; Suligoj, Andraz; Kete, Marko; Fanetti, Mattia; Stangar, Urska Lavrencic; Dionysiou, Dionysios D; Bozic, Ana Loncaric

    2016-09-01

    The study is aimed at evaluating the potential of immobilized TiO2-based zeolite composite for solar-driven photocatalytic water treatment. In that purpose, TiO2-iron-exchanged zeolite (FeZ) composite was prepared using commercial Aeroxide TiO2 P25 and iron-exchanged zeolite of ZSM5 type, FeZ. The activity of TiO2-FeZ, immobilized on glass support, was evaluated under solar irradiation for removal of diclofenac (DCF) in water. TiO2-FeZ immobilized in a form of thin film was characterized for its morphology, structure, and composition using scanning electron microscopy/energy-dispersive x-ray spectroscopy (SEM/EDX). Diffuse reflectance spectroscopy (DRS) was used to determine potential changes in band gaps of prepared TiO2-FeZ in comparison to pure TiO2. The influence of pH, concentration of hydrogen peroxide, FeZ wt% within the composite, and photocatalyst dosage on DCF removal and conversion efficiency by solar/TiO2-FeZ/H2O2 process was investigated. TiO2-FeZ demonstrated higher photocatalytic activity than pure TiO2 under solar irradiation in acidic conditions and presence of H2O2.

  16. Atomic-scale investigation of a new phase transformation process in TiO2 nanofibers.

    Science.gov (United States)

    Lei, Yimin; Li, Jian; Wang, Zhan; Sun, Jun; Chen, Fuyi; Liu, Hongwei; Ma, Xiaohua; Liu, Zongwen

    2017-03-30

    Crystallography of phase transformation combining transmission electron microscopy (TEM) with in situ heating techniques and X-ray diffraction (XRD) can provide critical information regarding solid-state phase transitions and the transition-induced interfaces in TiO2 nanomaterials theoretically and experimentally. Two types of reduced titanium oxides (Ti3O5, Ti6O11) are found during ex situ and in situ heating of TiO2 (B) nanofibers with a specific morphology of the {100} single form (SF) in air and vacuum. The results indicate that the phase transformation process from TiO2 (B) follows the TiO2 (B) → Ti3O5 → Ti6O11 → anatase sequence for the nanofibers with the {100} SF. The occurrence of such a phase transition is selective to the morphology of TiO2 (B) nanofibers. The corresponding orientation relationships (COR) between the four phases are revealed according to the TEM characterization. Four types of coherent interfaces, following the CORs are also found. They are TiO2 (B)/Ti3O5, TiO2 (B)/Ti6O11, Ti6O11/anatase and TiO2 (B)/anatase respectively. The habit plane for the TiO2 (B) to Ti3O5 transition is calculated as the {100}TB by using the invariant line model. The detailed atomic transformation mechanism is elucidated based on the crystallographic features of the four phases.

  17. Flame-made ultra-porous TiO2 layers for perovskite solar cells

    Science.gov (United States)

    Osorio Mayon, Yahuitl; Duong, The; Nasiri, Noushin; White, Thomas P.; Tricoli, Antonio; Catchpole, Kylie R.

    2016-12-01

    We report methyl ammonium lead iodide (MAPbI3) solar cells with an ultra-porous TiO2 electron transport layer fabricated using sequential flame aerosol and atomic layer depositions of porous and compact TiO2 layers. Flame aerosol pyrolysis allows rapid deposition of nanostructured and ultra-porous TiO2 layers that could be easily scaled-up for high-throughput low-cost industrial solar cell production. An efficiency of 13.7% was achieved with a flame-made nanostructured and ultra-porous TiO2 electrode that was coated with a compact 2 nm TiO2 layer. This demonstrates that MAPbI3 solar cells with a flame-made porous TiO2 layer can have a comparable efficiency to that of the control MAPbI3 solar cell with the well-established spin-coated porous TiO2 layer. The combination of flame aerosol and atomic layer deposition provides precise control of the TiO2 porosity. Notably, the porosity of the as-deposited flame-made TiO2 layers was 97% which was then fine-tuned down to 87%, 56% and 35% by varying the thickness of the subsequent compact TiO2 coating step. The effects of the decrease in porosity on the device performance are discussed. It is also shown that MAPbI3 easily infiltrates into the flame-made porous TiO2 nanostructure thanks to their high porosity and large pore size.

  18. Flame-made ultra-porous TiO2 layers for perovskite solar cells.

    Science.gov (United States)

    Mayon, Yahuitl Osorio; Duong, The; Nasiri, Noushin; White, Thomas P; Tricoli, Antonio; Catchpole, Kylie R

    2016-12-16

    We report methyl ammonium lead iodide (MAPbI3) solar cells with an ultra-porous TiO2 electron transport layer fabricated using sequential flame aerosol and atomic layer depositions of porous and compact TiO2 layers. Flame aerosol pyrolysis allows rapid deposition of nanostructured and ultra-porous TiO2 layers that could be easily scaled-up for high-throughput low-cost industrial solar cell production. An efficiency of 13.7% was achieved with a flame-made nanostructured and ultra-porous TiO2 electrode that was coated with a compact 2 nm TiO2 layer. This demonstrates that MAPbI3 solar cells with a flame-made porous TiO2 layer can have a comparable efficiency to that of the control MAPbI3 solar cell with the well-established spin-coated porous TiO2 layer. The combination of flame aerosol and atomic layer deposition provides precise control of the TiO2 porosity. Notably, the porosity of the as-deposited flame-made TiO2 layers was 97% which was then fine-tuned down to 87%, 56% and 35% by varying the thickness of the subsequent compact TiO2 coating step. The effects of the decrease in porosity on the device performance are discussed. It is also shown that MAPbI3 easily infiltrates into the flame-made porous TiO2 nanostructure thanks to their high porosity and large pore size.

  19. Tunable Pseudocapacitance in 3D TiO2-δ Nanomembranes Enabling Superior Lithium Storage Performance.

    Science.gov (United States)

    Huang, Shaozhuan; Zhang, Lin; Lu, Xueyi; Liu, Lifeng; Liu, Lixiang; Sun, Xiaolei; Yin, Yin; Oswald, Steffen; Zou, Zhaoyong; Ding, Fei; Schmidt, Oliver G

    2017-01-24

    Nanostructured TiO2 of different polymorphs, mostly prepared by hydro/solvothermal methods, have been extensively studied for more than a decade as anode materials in lithium ion batteries. Enormous efforts have been devoted to improving the electrical conductivity and lithium ion diffusivity in chemically synthesized TiO2 nanostructures. In this work we demonstrate that 3D Ti(3+)-self-doped TiO2 (TiO2-δ) nanomembranes, which are prepared by physical vapor deposition combined with strain-released rolled-up technology, have a great potential to address several of the long-standing challenges associated with TiO2 anodes. The intrinsic electrical conductivity of the TiO2 layer can be significantly improved by the in situ generated Ti(3+), and the amorphous, thin TiO2 nanomembrane provides a shortened Li(+) diffusion pathway. The fabricated material shows a favorable electrochemical reaction mechanism for lithium storage. Further, post-treatments are employed to adjust the Ti(3+) concentration and crystallinity degree in TiO2 nanomembranes, providing an opportunity to investigate the important influences of Ti(3+) self-doping and amorphous structures on the electrochemical processes. With these experiments, the pseudocapacitance contributions in TiO2 nanomembranes with different crystallinity degree are quantified and verified by an in-depth kinetics analysis. Additionally, an ultrathin metallic Ti layer can be included, which further improves the lithium storage properties of the TiO2, giving rise to the state-of-the-art capacity (200 mAh g(-1) at 1 C), excellent rate capability (up to 50 C), and ultralong lifetime (for 5000 cycles at 10 C, with an extraordinary retention of 100%) of TiO2 anodes.

  20. Synthesis and photonic band calculations of NCP face-centered cubic photonic crystals of TiO2 hollow spheres.

    Science.gov (United States)

    Zhu, Yong-zheng; Cao, Yan-ling; Li, Zhi-hui; Ding, Juan; Liu, Jun-song; Chi, Yuan-bin

    2007-02-01

    With the help of self-assembly, thermal sintering, selective etching techniques and sol-gel process, the non-close packed (ncp) face-centered cubic (fcc) photonic crystals of titanium dioxide (TiO2) hollow spheres connected by TiO2 cylindrical tubes have been fabricated using silica template. The photonic bandgap calculations indicate that the ncp structure of TiO2 hollow spheres was easier to open the pseudogaps than close packed system at the lowest energy.