敏化TiO2纳米晶多孔膜电极的制备与表征

研究了染料敏化TiO2纳米晶多孔薄膜电极的制备、表征及其光电转换性质，采用溶胶－凝胶法液压涂层制备了TiO2纳米晶多孔薄膜，在无水乙醇中利用薄膜吸附染料2，2′－联吡啶－4，4′－二甲酸合硫氰酸钌进行敏化处理，并利用XPS、AFM、XRD、SEM杉可见－紫外分光光度仪对敏化TiO2纳米晶多孔薄膜进行了表征分析。研究结果表明：薄膜中纳米粒子晶型主要为锐钛矿，粒径在20-30nm，多孔薄膜的孔径在50－200nm；染料敏化多孔薄膜表面吸附了一个单分子层的染料分子，敏化薄膜对可见光有很强的吸收作用，用此薄膜制作的太阳能电池具有较高的光电转化效率，电池效率达到2％，这种薄膜电极改进后可用于制作敏化太阳能电池的光阳极。     

金红石TiO_2纳米棒阵列的生长机理及在染料敏化太阳电池中的应用

用水热法制备了金红石TiO2纳米棒阵列光阳极,并对样品进行XRD、SEM和HRTEM表征分析。文中研究了不同水热条件对金红石TiO2纳米棒阵列的生长形貌影响,详细探讨了其水热生长机理。结果表明:金红石纳米棒的直径和长度随着水热体系能量增加而增加;添加剂对金红石纳米棒的水热生长影响较大;在金红石TiO2纳米棒阵列光阳极水热生长过程中,会同导电玻璃衬底之间形成致密层,该致密层对DSSCs的光电转换性能影响较严重。将制备的金红石TiO2纳米棒阵列光阳极应用于DSSCs中,在AM 1.5 100 mW/cm2(air-mass 1.5,AM 1.5意为光线通过大气的实际距离为大气垂直厚度的1.5倍)标准条件下,测得1.81%的光电转换效率。     

ZnO/TiO2纳米管晶膜电极的制备及光电性能

采用水热法制备了ZnO纳米棒,以ZnO纳米棒为原料制备出ZnO/TiO2纳米管晶膜电极并应用于染料敏化太阳能电池.用扫描电镜(SEM)、X射线衍射仪(XRD)、X射线能谱仪(EDX)和N2吸脱附分析等研究了样品的结构、表面形貌和化学组成,并通过紫外可见光度计和电化学工作站探讨了煅烧温度在80~600℃范围内ZnO/TiO2纳米管电极的光电化学性能.此外,研究经TiCl4化学处理的ZnO/TiO2纳米管电极光电性能的改善情况.结果表明,600℃煅烧的ZnO/TiO2纳米管电极制备的染料敏化太阳能电池表现出较优的光电性能,其短路电流密度(Jsc)为2.28 mA/cm2,开路电压(Voc)为0.631 V,光电转换效率η为0.66%.600℃煅烧的ZnO/TiO2纳米管经TiCl4处理后的染料敏化太阳能电池的光电性能得到显著改善,其光电转换效率η提高到1.06%.     

阳极氧化法制备TiO2纳米管阵列及其光电性能研究

采用阳极氧化法在钛片上制备了TiO2纳米管阵列光电极，利用扫描电子显微镜（SEM）和X射线衍射仪（xRD）对TiO2纳米管的形貌和结构进行了表征，详细考察了氧化工艺参数对纳米管阵列形貌的影响，并通过稳态光电响应技术对TiO2纳米管电极的光电化学性能进行了研究．结果表明，在1wt％HF电解液中，控制氧化电压为20V，反应30min后，在Ti表面获得了垂直导向的TiO2纳米管阵列，孔径约为90nm，管壁厚度约为10nm．经600℃退火处理后，TiO2纳米管阵列为锐钛矿型与金红石型的混晶结构，此时电极的光电性能最佳，与TiO2纳米多孔膜电极相比，光电性能大幅提高．     

大小颗粒混和的纳晶多孔TiO2薄膜电极的制备及其性能研究

把大小颗粒的纳晶TiO2进行混合,制备了纳晶多孔TiO2薄膜电极并应用于染料敏化太阳能电池中.研究表明,混合一定量的大颗粒纳晶,改善了纳晶多孔TiO2薄膜对染料的吸附量和薄膜电极对光的散射性能,提高了光电输出,在100mW/cm2光照条件下,染料敏化太阳能电池的光电转换效率达到5.66%.     

CdS_xSe_(1-x)包覆TiO_2纳米棒壳核结构的制备及其在杂化太阳电池的应用

采用水热法在掺氟的SnO2透明导电玻璃(FTO)基底上制备了金红石型的TiO2纳米棒阵列;然后采用电化学方法在TiO2纳米棒阵列上沉积不同厚度的CdSxSe1-x纳米晶,形成了CdSxSe1-x纳米晶包覆TiO2纳米棒的CdSxSe1-x/TiO2壳核结构;利用扫描电镜(SEM)、能谱分析(EDS)、X射线衍射(XRD)、紫外-可见漫反射吸收光谱(UV-Vis DRS)等对其形貌、结构组成等进行了分析和表征,结合循环伏安法及其吸收光谱确定了CdSxSe1-x纳米晶的能级位置。最后以P3HT/CdSxSe1-x/TiO2复合薄膜材料为光活性层组装成固态纳米结构杂化太阳电池,研究了CdSxSe1-x壳层厚度对该电池光电转换性能的影响,结果表明转换效率最高可达到0.68%。     

微孔结构TiO2薄膜在准固态染料敏化太阳电池上的应用

采用200 nm聚苯乙烯(PS)造孔可以改善TiO2半导体薄膜的散射光性能,提高了准固态染料敏化太阳电池的光电性能。用10%聚苯乙烯造孔制备TiO2半导体组装的染料敏化太阳电池,在100 mW/cm2光强下电池光电转换效率达到2.94%,与不含造孔剂电池相比,光电转换效率提高52%。薄膜光学性能和入射单色光子–电子转化效率(IPCE)研究表明,电池光电性能的提高与薄膜的光散射改善和电池中染料的光捕获效率增大密切相关。     

基于介孔TiO_2/石墨烯修饰的TiO_2纳米线光阳极的染料敏化太阳能电池（英文）

本工作制作了基于介孔TiO2/石墨烯修饰的TiO2纳米线光阳极的染料敏化太阳能电池,并进行表征。光阳极结合了介孔TiO2的高染料吸附率,TiO2纳米线的高载流子传导率和石墨烯的高电子收获能力等优点,使器件光电转换效率有了很大的提高。制作出的染料敏化太阳能电池光电转换效率高达7.58%,比纯纳米线制作的电池约提高了1.5倍,在拥有相似一维结构的染料敏化太阳能电池中具有较大优势。     

鸭跖草色素敏化TiO_2纳米管太阳能电池的研究

以高度有序TiO2纳米管阵列作为光阳极,鸭跖草色素作为敏化剂制备了天然染料敏化太阳能电池。阳极氧化6h制备的TiO2纳米管作为电极的电池的光电转换效率约达0.52%,短路电流为1.53mA/cm2。比较不同管长TiO2纳米管阵列对电池的光电性能的影响。利用紫外-可见光光谱仪研究鸭跖草色素的光吸收性能。利用电化学阻抗谱分析电池的界面阻抗。研究表明适当提高TiO2纳米管长度可以有效提高天然染料敏化太阳能电池的光电性能。     

丝网印刷法制备染料敏化太阳能电池光电性能的研究

采用水热法制备TiO2纳米颗粒,将获得的TiO2纳米颗粒制备成胶体,采用丝网印刷法在FTO表面刷涂制备染料敏化太阳能电池（DSSC）光阳极,通过扫描电子显微镜对电极表征和电池光电性能测试,探讨印刷层数及入射光强对DSSC光电性能的影响,实验结果表明,将制备的光阳极组装成电池后具有较好的光电性能,当印刷层数为8层、光强为80W／m2时,电池取得最好的光电性能。     

Effect of cobalt doping on the phase transformation of TiO2 nanoparticles

Co-doped TiO2 nanoparticles containing 0.0085, 0.017, 0.0255, 0.034, and 0.085 mol % Co(III) ion dopant were synthesized via sol-gel and dip-coating techniques. The effects of metal ion doping on the transformation of anatase to the rutile phase have been investigated. Several analytical tools, such as X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray analysis (EDAX) were used to investigate the nanoparticle structure, size distribution, and composition. Results obtained revealed that the rutile to anatase concentration ratio increases with increase of the cobalt dopant concentration and annealing temperature. The typical composition of Co-doped TiO2 was Ti(1-x)Co(x)O2, where x values ranged from 0.0085 to 0.085. The activation energy for the phase transformation from anatase to rutile was measured to be 229, 222, 211, and 195 kJ/mole for 0.0085, 0.017, 0.0255, and 0.034 mol % Co in TiO2, respectively.     

Effects of TiO2 structures in dye-sensitized solar cell

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%.     

Optimized method for preparation of TiO2 nanoparticles dispersion for biological study

The objective of the present study was to develop a practical method to prepare a stable dispersion of TiO2 nanoparticles for biological studies. To address this matter a variety of different approaches for suspension of nanoparticles were conducted. TiO2 (rutile/anatase) dispersions were prepared in distilled water following by treated with different ultrasound energies and various dispersion stabilizers (1.0% carboxymethyl cellulose, 0.5% hydroxypropyl methyl cellulose K4M, 100% fetal bovine serum, and 2.5% bovine serum albumin). The average size of dispersed TiO2 (rutile/anatase) nanoparticles was measured by dynamic light scattering device. Agglomerate sizes of TiO2 in distilled water and 100% FBS were estimated using TEM analysis. Sedimentation rate of TiO2 (rutile/anatase) nanoparticles in dispersion was monitored by optical absorbance detection. In vitro cytotoxicity of various stabilizers in 16-HBE cells was measured using MTT assay. The optimized process for preparation of TiO2 (rutile/anatase) nanoparticles dispersion was first to vibrate the nanoparticles by vortex and disperse particles by ultrasonic vibration in distilled water, then to add dispersion stabilizers to the dispersion, and finally to sonicate the nanoparticles in dispersion. TiO2 (rutile/anatase) nanoparticles were disaggregated sufficiently with an ultrasound energy of 33 W for 10 min. The formation of TiO2 (rutile/anatase) agglomerates in distilled water was decreased obviously by addition of 1.0% CMC, 0.5% HPMC K4M, 100% FBS and 2.5% BSA. For the benefit of cell growth, FBS is the most suitable stabilizer for preparation of TiO2 (rutile/anatase) particle dispersions and subsequent investigation of the in vivo and in vitro behavior of TiO2 (rutile/anatase) nanoparticles. This method is practicable to prepare a stable dispersion of TiO2 (rutile/anatase) nanoparticles for at least 120 h.     

Pulsed laser deposition of titania on rutile nanorod arrays

Oriented rutile nanorod arrays are precipitated on metallic Ti plates from a precursor derived by interactions between Ti and aqueous hydrogen peroxide. Pulsed laser deposition (PLD) is then carried out to deposit titania on the nanorod arrays, in comparison with bare Ti substrates, utilizing a high-temperature sintered rutile target in oxygen atmosphere. It is found that dense and homogeneous titania thin films are obtained on Ti substrates; while growth on the rutile nanorod arrays is epitaxial, resulting in enlarged nanorods conformally covered with titania. Titania grown on both Ti substrates and rutile nanorod arrays is either pure rutile or a mixture of anatase and rutile, with the formation of anatase favored by an increasing oxygen pressure during the PLD procedure. The surface roughness and the particle size of the dense titania films on Ti substrates increase as a result of increasing oxygen pressure and prolonged deposition time. The PLD-induced epitaxial growth of titania is inhibited by increasing substrate temperatures. The photocatalytic experiments reveal a significantly enhanced activity for the rutile nanorod arrays after a subsequent PLD treatment.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

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.     

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

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

Phase-pure TiO(2) nanoparticles: anatase, brookite and rutile

We report on the synthesis of phase-pure TiO(2) nanoparticles in anatase, rutile and brookite structures, using amorphous titania as a common starting material. Phase formation was achieved by hydrothermal treatment at elevated temperatures with the appropriate reactants. Anatase nanoparticles were obtained using acetic acid, while phase-pure rutile and brookite nanoparticles were obtained with hydrochloric acid at a different concentration. The nanomaterials were characterized using x-ray diffraction, UV-visible reflectance spectroscopy, dynamic light scattering, and transmission electron microscopy. We propose that anatase formation is dominated by surface energy effects, and that rutile and brookite formation follows a dissolution-precipitation mechanism, where chains of sixfold-coordinated titanium complexes arrange into different crystal structures depending on the reactant chemistry. The particle growth kinetics under hydrothermal conditions are determined by coarsening and aggregation-recrystallization processes, allowing control over the average nanoparticle size.     

Photocatalytic titanium dioxide composite

In recent years, Titanium Dioxide (TiO2) has gained much more interest for its semiconducting properties for use as photocatalytic material because it rapidly and completely mineralizes organic without harmful byproducts. Based on inspiration from biology, which uses organic structures to guide nucleation and growth of minerals, we demonstrate controlled synthesis of TiO2 using a hydrophilic synthetic polymer. In the absence of the polymer, TiO2 completely transforms to rutile by 72 hours, however with the addition of the polymer larger anatase crystallites are observed due to the reduced number of nuclei formed. Under these conditions, complete transformation to rutile was not observed due to diffusion-limited growth of TiO2 as well as the presence of an organic coating on the crystallites. However nanoparticles are difficult to recover from effluent streams. We use the polymer to develop bulk composite TiO2-organic structures which can be fabricated and tailored as a stand alone photocatalysts, eliminating the need for nanoparticle recovery systems, thereby reducing processing costs.     

Effects of Additive AlCl3 on Crystal Phase, Particle Size and Microstructural Parameters of Nanocrystalline TiO2 Prepared by HF-PCVD

Nanocrystalline TiO2 was prepared by high frequency plasma chemical vapor deposition (HF-PCVD). The effects of additive AlCl3 on crystal phase, particle size and microstructurai parameters of TiO2 nanocrystallites were investigated by X-ray diffraction(XRD) and transmission electron microscopy (TEM). The nanocrystallites obtained experimentally are mixture of anatase and rutile, the uniform diameters of particles are about 30 nm. The phase transformation from anatase to rutile was accelerated by AlCl3, and rutile content is increased from 26.7 wt pct to 53.6 wt pct with increasing of addition of AlCl3 from 0.0 wt pct to 5.0 wt pct. The particle size is reduced and the size distribution becomes very narrow. The crystal lattice constants have the trend to decrease, and celi volumes appear as shrinkable     

TiO2 nanorod films grown on Si wafers by a nanodot-assisted hydrothermal growth

We report the controlled hydrothermal growth of rutile TiO₂ nanorods on Si wafers by using an anatase TiO₂ nanodot film as an assisted growth layer. The anatase nanodot film was prepared on the wafer by phase-separation-induced self-assembly and subsequent heat-treatment at 500 °C. The nanodots on the wafer were then subjected to hydrothermal treatment to induce the growth of rutile TiO₂ nanorod films. The size and dispersion density of the resulting TiO₂ nanorods could be varied by adjusting the Ti ion concentration in the growth solution. The TiO₂ nanorods were of the rutile phase and grew in the [001] direction. The growth mechanism reveals that the growth of the rutile nanorods was wholly dependent on the existence of rutile TiO₂ seeds, which could be formed by the dissolution-reprecipitation of the anatase nanodots during hydrothermal treatment or under the high-temperature conditions of the subsequent heat-treatment of the as-prepared nanodots. In controlling the rutile nanorod growth, the anatase nanodots show more efficiency than a dense anatase film. Preliminary evaluations of the rutile nanorod films have demonstrated that the wettability changed from highly hydrophobic to superhydrophilic and that the photocatalytic activity was enhanced with increasing nanorod dispersion density.