Nafion薄膜中单分散TiO2纳米晶体的合成

采用全氟化离子聚合物薄膜(钠型Nafion薄膜)作模板合成了平均直径为4.0nm的TiO₂晶体粒子。利用高分辨电子显微镜(HRTEM)、X-射线衍射仪(XRD)和紫外-可见光谱仪(UV-VIS)，对Nafion中TiO₂的含量、粒子大小分布、相变条件、纳米晶体微观型貌及其结构、Nafion薄膜结构和TiO₂粒子形成机理等进行了研究。研究结果表明，Nafion中Ti⁴⁺含量不仅与起始原料有关，还与起始物浓度有关。TiO₂在Nafion中的形成速度主要受控于水在膜中的扩散速度，而TiO₂晶体粒子的大小与分布则取决于Nafion的孔径，与起始原料种类以及晶化条件无关。文中还探索了无定型TiO₂转变成单分散晶体的各种途径，详细讨论了TiO₂晶体粒子合成的影响因素。     

钛、铝和玻璃上TiO2光催化膜的失活研究

采用浸渍提拉法，在平行条件下制备了钛、铝和玻璃载体上的TiO₂膜TiO₂ / Ti、TiO₂ / Al和TiO₂ / G，利用X射线光电子能谱(XPS)、原子力显微镜(AFM)和光催化降解实验等手段对膜样品进行了表征和活性评价。实验结果表明，在铝和玻璃基材上制膜时发生了显著的基材元素溢出，使各膜样品的化学组成不同，同时TiO₂粒子和膜表面形貌也因前驱物烧结行为不同而差异较大。TiO_{2相似文献}   

离子交换膜中CdS单分散纳米晶的合成及其光学性质

以硫代乙酰胺(TAA)为前驱体, 采用液相反应在全氟磺酸离子交换膜(Nafion)中自组装得到了均匀分布、单分散的纳米CdS晶体；与文献报道的前驱体如Na₂S和H₂S不同, TAA可以在全氟磺酸离子膜中均匀扩散, 最终在Nafion薄膜中得到均匀分布的纳米CdS晶体. 利用高分辨电子显微镜(HRTEM)、X射线衍射仪(XRD)和能量散射X射线分析(EDXA)研究了Nafion薄膜模板中CdS纳米晶体的形成机理、晶粒大小和分布；采用紫外- 可见吸收光谱和荧光光谱分析了Nafion薄膜中单分散纳米CdS晶体的光学性质. 结果表明, 随CdS纳米晶体尺寸的减小, 量子尺寸效应明显增强；在紫外吸收谱中表现为吸收边明显蓝移, 而在光致发光谱中, 表现为带边发射的蓝移.     

TiO2纳米纤维无纺布的制备及光催化性能研究

以聚乙烯吡咯烷酮(PVP)作为配位剂与钛酸正丁酯(Ti(C₄H₉O)₄)反应制得前驱体，再以乙醇为溶剂，CH3COOH作为催化剂，采用静电纺丝法制得PVP/TiO₂复合纳米纤维，经550 ℃、700 ℃和900 ℃焙烧后分别得到以锐钛矿型的TiO₂为主、以金红石型TiO₂为主和完全金红石晶型的TiO₂纳米纤维。对所制得的纳米纤维的结晶度、纯度和形貌，分别采用差热-热重分析(TG-DTA)、红外光谱(IR)、X射线粉末衍射(XRD)、扫描电镜(SEM)等进行了表征。光降解苯酚水溶液的实验结果表明，550 ℃下煅烧得到的以锐钛矿占主体的TiO₂纳米纤维，2 h使浓度为50 mg·L^-1苯酚水溶液的降解率超过85%，这充分说明这种TiO₂电纺纳米纤维具有良好的光催化性能。     

溶胶-凝胶-水热晶化法制备锐钛矿TiO2纳米膜的耐蚀性能

以钛酸正丁酯为前驱体, 采用溶胶-凝胶-水热晶化法在不锈钢(SS)表面制备TiO₂纳米膜. 利用X射线衍射(XRD)、Raman光谱、场发射扫描电子显微镜(SEM)、原子力显微镜(AFM)和俄歇电子能谱(AES)表征了TiO₂纳米膜的晶型、表面形貌和表面化学组成. 通过极化曲线和电化学阻抗谱(EIS)研究了TiO₂纳米膜的耐蚀性能. 170 °C下水热晶化制备的锐钛矿TiO₂与450 °C焙烧制备的锐钛矿TiO₂的结晶度类似, 但两种TiO₂薄膜的表面结构存在明显差异, 水热晶化法制备的TiO₂纳米膜在3.5% (w) NaCl溶液中的耐蚀性能优于焙烧法制备的.     

SnCl4对纳米二氧化钛晶相结构的低温转变控制研究

采用二种方法制备了低温下晶相结构可控制转变的纳米二氧化钛。一种方法是采用乙醇作溶剂的溶胶-凝胶法,通过控制SnCl₄的添加量,便可在450℃热处理下实现纳米TiO₂从纯锐钛矿到不同比例的复合相直至纯金红石相的转变。另一种方法是采用钛酸丁酯为原料直接低温水解,通过加入不同量的SnCl₄,制备了具有晶态结构的二氧化钛复合溶胶,在120℃下干燥处理便可实现TiO₂从锐钛矿到不同比例的复合相(金红石型、锐钛矿型和板钛矿型)直至纯金红石相的转变,制备所需晶态结构的纳米TiO₂。所有样品进行了透射电镜与XRD表征,制备的纳米TiO₂及其TiO₂-SnO₂纳米复合材料颗粒小、分布均匀、分散性好,没有检测到SnO₂晶体的X-衍射特征峰。     

纳米TiO2有机表面改性的研究

利用硅烷偶联剂(KH-550)对表面包覆氧化硅的金红石相纳米TiO₂进行了有机表面改性。采用红外光谱(IR)、X射线光电子能谱(XPS)、热分析(TG-DTA)、BET、透射电镜(TEM)、润湿性和分散性实验等对表面改性前后的纳米TiO₂进行了表征。红外光谱和X射线光电子能谱表明，KH-550以化学键合的方式结合在纳米TiO₂的表面，并形成了有机包覆层。经测量，纳米TiO₂表面的KH-550的质量分数约为2.0%。讨论了产生KH-550理论包覆量与实际包覆量差异的原因。TEM、TG和BET得出的结果显示，在纳米TiO₂有机表面改性过程中存在明显的团聚现象，改进分散纳米TiO₂的方法是提高有机改性效果的关键。润湿性实验和分散性实验表明，经KH-550表面改性的纳米TiO₂同时具有亲水性和亲油性。     

超声场中纳米TiO2表面包覆氧化硅的研究

在超声场中，通过硅酸钠水解生成的无定形氧化硅对金红石相纳米TiO₂进行表面包覆，利用红外光谱、X射线光电子能谱、X射线衍射和透射电镜对所得样品进行了表征，并对纳米TiO₂的光稳定性和分散性进行了评价。红外光谱和X射线光电子能谱表明，氧化硅以化学键合的方式沉积在纳米TiO₂的表面，在包覆层和纳米TiO₂颗粒之间的界面上形成了Ti-O-Si键。TEM照片、表面元素分析和光稳定性实验显示，氧化硅在纳米TiO₂表面形成了均匀的包覆层，超声场有助于提高包覆层的均匀性和致密性。氧化硅的表面包覆提高了纳米TiO₂在水中的分散性、紫外线屏蔽能力和可见光透过性。随着氧化硅含量的增加，纳米TiO₂的光稳定性逐渐提高，当m(SiO₂)∶m(TiO₂)>1∶5时，纳米TiO₂的光稳定性基本不变，而且在热处理过程中纳米TiO₂的晶粒生长得到有效抑制。     

Au改性TiO2纳米复合物对人结肠癌细胞的光催化杀伤作用

提出了通过TiO₂表面修饰纳米Au的方法来提高纳米TiO₂光催化杀伤癌细胞的效率. 采用化学还原法合成了Au改性的TiO₂ (Au/TiO₂)纳米复合物, 并研究了不同掺杂量(1 wt%, 2 wt%, 4 wt%)的Au/TiO₂对人结肠癌LoVo细胞的光催化杀伤效应. 结果显示, Au的掺杂大大地提高了TiO₂纳米粒子光催化杀伤结肠癌LoVo细胞的效率, 而且Au掺杂量的高低影响Au/TiO₂光催化杀伤癌细胞的效率, 掺金量为2%的Au/TiO₂对结肠癌LoVo细胞具有最高的光催化杀伤效率. 在光强为1.8 mW/cm²的紫外灯(λ_max＝365 nm)下光照110 min, 50 μg/mL掺金量为2%的Au/TiO₂能够杀死所有的癌细胞, 而同样浓度的TiO₂只能杀死70%的癌细胞.     

掺杂纳米TiO2：乙醇溶胶脉冲激光法连续制备及荧光特性

采用聚焦脉冲激光轰击(PLA)浸于流动乙醇中不同金属氧化物掺杂的二氧化钛固体靶，连续制备得到一系列经MoO₃、Eu₂O₃、Fe₂O₃、WO₃等掺杂的新型纳米TiO₂乙醇溶胶。UV-Vis、荧光光谱和XRD结果表明：在所研究的掺杂纳米TiO₂乙醇溶胶中，MoO₃掺杂使纳米TiO₂乙醇溶胶荧光增强最大，当MoO₃掺杂量(ψ)在0.02%～0.50%时，其掺杂的纳米TiO₂乙醇溶胶荧光强度增强，掺杂量为0.05%时荧光强度高达1.3×10⁴(a.u.)；此外发现与sol-gel掺杂法相比，预研磨混合掺杂能更明显增强纳米TiO₂乙醇溶胶荧光。     

Mechanism of the formation of photosensitive nanostructured TiO<Subscript>2</Subscript> with low content of CdS nanoparticles

A method for synthesizing a CdS/TiO₂ composite material, active in the visible region, was described. The CdS/TiO₂ composite was obtained by the sol–gel synthesis of nanostructured TiO₂ in a medium of a stable colloidal solution of CdS nanoparticles. The TiO₂ matrix produced by the sol–gel process is amorphous and contains a nanocrystalline anatase phase, the content of which depends on the Ti(OBu)₄ hydrolysis rate. The content of CdS nanoparticles forming in the colloidal solution and participating in the TiO₂ matrix sensitization is determined by the initial CdS: Ti(OBu)₄ ratio. Although the content of CdS nanoparticles in the composite is low (no more than 3 wt %), the composite demonstrates catalytic activity in the visible region, thus proving the possibility of reducing the content of toxic CdS nanoparticles in the TiO₂ matrix without decreasing the photosensitivity of the CdS/TiO₂ composite.     

Effect of Processing Parameters on the Optical Properties of TiO<Subscript>2</Subscript>/Ormosil Planar Waveguide

Hybrid TiO₂/ormosil waveguiding films have been prepared by the sol-gel method at low thermal treatment temperature of 150C. The influence of processing parameters including the molar ratios of titanium butoxide (Ti(OBu)₄)/3-glycidoxypropyltrimethoxysilane (GLYMO) and H₂O/Ti(OBu)₄ (expressed as R), especially aging of sol on the optical properties was investigated. The optical properties of films were measured with scanning electron microscope (SEM), UV/VIS/NIR spectrophotometer (UV-Vis), m-line and the scattering-detection method. The results indicate that the film thickness increases with the increase of sol aging time, but the variation of refractive index as a function of sol aging time depends on the relative ratios of GLYMO to Ti(OBu)₄. Higher transmittance and lower attenuation of the planar waveguide can be obtained in the sol with lower Ti(OBu)₄ contents and shorter aging time.     

Study of intermolecular interactions in a system for equilibrium catalytic transesterification of esters. 1. Reaction of boron,titanium, and arsenic butoxides with esters according to IR fourier spectroscopic data

IR spectroscopy was used to study solutions of esters of PhCOOR (R=Me, Bu, C₇H₁₅, (CH₂)₂OBu) in B(OBu)₃, Ti(OBu)₄, and As(OBu)₃ and in mixtures of the latter with CCl₄ and hexane. It is shown that weak complexes form between the ester molecules and B(OBu)₃ and Ti(OBu)₄, As(OBu)₃ behaves with respect to the esters as a nonpolar solvent. Intermolecular interaction of the esters with butoxides occurs at the alkoxide oxygen in the ester. A mechanism of the exchange of the alkoxyl radical in the reaction of Ti(OBu)₄ with PhCOOMe is proposed on the basis of kinetic measurements.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1991–1995, September, 1990.     

SiO2表面吸附层中钛酸丁酯的反应过程

研究了硅胶表面富含水吸附层中钛酸丁酯的反应过程.在不同条件的吸附相反应制备中,首先利用分光光度计测定了乙醇体相中Ti含量随反应进行的变化过程.结果表明由于吸附层中钛酸丁酯的快速水解,乙醇体相中的Ti含量在反应前60 min快速减少.钛酸丁酯与硅胶表面羟基、化学吸附层和物理吸附层中的水分子的反应活性均不相同,这导致了Ti含量曲线的不同变化.EDAX的分析结果表明温度对乙醇体相中钛酸丁酯的反应过程影响很小,但对吸附相反应有着较为复杂的影响,Ti含量和TiO2形貌都随着温度升高出现了两类变化.本文提出了温度对化学吸附和物理吸附的不同影响来解释样品中Ti含量和TiO2形貌的不同变化.     

Preparation,photocatalytic activity and mechanism of nano-Titania/Nafion hybrid membrane

Nano-Titania/Nafion (TiO₂/Nafion) hybrid membranes were prepared by recasting, using Nafion solution and TiO₂ anatase hydrosol as the raw materials. The microstructure of the hybrid membrane was characterized by X-ray diffraction, high-resolution transmission electron microscopy (HR-TEM), X-ray Photoelectron Spectroscopy and Fourier Transform Infrared Spectroscopy (FT-IR). The photocatalytic properties of TiO₂/Nafion hybrid membranes were evaluated. Furthermore, endurance of photocatalytic activity of the hybrid membrane was investigated. The results indicate that the TiO₂ Nanoparticles are bounded to Nafion molecule via Ti-O-S bonds and the formed flocculates are distributed homogeneously throughout the recasting Nafion membrane, while the initial pure anatase TiO₂ nanoparticles remain intact in re-crystallized membrane. The hybrid membranes possessed excellent photocatalytic activities with and without H₂O₂. Moreover, the degradation of photocatalytic activities has been better controlled with the presence of H₂O₂.     

Alumina-titania oxides: Synthesis and characterization

Alumina-titania mixed oxides with nominal atomic ratios Al/Ti=25 and 2 have been synthesized by cohydrolysis of Al(OsecBu)₃ and Ti(OBu)₄. The oxides were amorphous at 500°C, showing only short range order. Ti was incorporated in alumina in a well dispersed way creating a true Al/Ti mixed oxide. The strength of surface acid sites and specific surface areas were increased at the higher Ti content. The TiO₂ anatase phase was avoided and rutile was formed directly at 900°C.     

Nafion/TiO<Subscript>2</Subscript> hybrid membrane fabricated via hydrothermal method for vanadium redox battery

To improve the performance of Nafion membrane as a separator in vanadium redox battery (VRB) system, a Nafion/TiO₂ hybrid membrane was fabricated by a hydrothermal method. The primary properties of this hybrid membrane were measured and compared with the Nafion membrane. The Nafion/TiO₂ hybrid membrane has a dramatic reduction in crossover of vanadium ions compared with the Nafion membrane. The results of scanning electron microscope, energy dispersive X-ray spectroscopy, and X-ray diffraction of the hybrid membrane revealed that the TiO₂ phase was formed in the bulk of the prepared membrane. Cell tests identified that the VRB with the Nafion/TiO₂ hybrid membrane presented a higher coulombic efficiency (CE) and energy efficiency (EE), and a lower self-discharge rate compared with that of the Nafion system. The CE and EE of the VRB with the hybrid membrane were 88.8% and 71.5% at 60 mA cm⁻², respectively, while those of the VRB with Nafion membrane were 86.3% and 69.7% at the same current density. Furthermore, cycling tests indicated that the Nafion/TiO₂ hybrid membrane can be applied in VRB system.     

Gold particles supported on self-organized nanotubular TiO2 matrix as highly active catalysts for electrochemical oxidation of glucose

Au/TiO₂/Ti electrode was prepared by a two-step process of anodic oxidation of titanium followed by cathodic electrodeposition of gold on resulted TiO₂. The morphology and surface analysis of Au/TiO₂/Ti electrodes was investigated using scanning electron microscopy and EDAX, respectively. The results indicated that gold particles were homogeneously deposited on the surface of TiO₂ nanotubes. The nanotubular TiO₂ layers consist of individual tubes of about 60–90 nm in diameter, and the electrode surface was covered by gold particles with a diameter of about 100–200 nm which are distributed evenly on the titanium dioxide nanotubes. This nanotubular TiO₂ support provides a high surface area and therefore enhances the electrocatalytic activity of Au/TiO₂/Ti electrode. The electrocatalytic behavior of Au/TiO₂/Ti electrodes in the glucose electro-oxidation was studied by cyclic voltammetry. The results showed that Au/TiO₂/Ti electrodes exhibit a considerably higher electrocatalytic activity toward the glucose oxidation than that of gold electrode.     

Synthesis and Ex-situ Characterization of Nafion/TiO2 Composite Membranes for Direct Ethanol Fuel Cell

Nafion/TiO₂ composite membranes for different loadings of TiO₂ were prepared by casting method for the possible application in direct ethanol fuel cell (DEFC). The properties of the composite membranes were investigated by scanning electron microscopy (SEM), x-ray diffraction (XRD), thermogravimetric analyser (TGA), ion exchange capacity, water and alcohol uptake, swelling ratio, proton conductivity, and ethanol crossover. The observed characteristics of the membranes were evaluated for DEFC and compared with the direct methanol fuel cell (DMFC) membrane. The analysis reveales a significant influence on the TiO₂ surface characteristics, water and alcohol uptake, and swelling of the membrane. The TiO₂ composite membranes exhibited a sharp decrease in methanol and ethanol crossover for 5% TiO₂ and the proton conductivity was heighest for 1% TiO₂ loading. The best compromise between proton conductivity and crossover has been found out with the help of the characteristic factor ϕ. The optimum loading of 5% TiO₂ composite membrane has shown the maximum characteristic factor.