半导体光催化氧化技术作为一种新兴的绿色环保技术，可广泛应用于空气净化、废水处理、消毒杀菌等众多领域，具有良好的发展前景。纳米二氧化钛因其具有较高的光化学活性，良好的生物、化学惰性以及耐腐蚀性，成为最常用的半导体光催化剂。但TiO2在实际应用中也面临着一些问题，如纳米TiO2的光生电子、空穴复合过快导致其光量子效率过低，不利于光催化活性的提高；TiO2的禁带宽度较宽，光吸收范围仅限于紫外光区域，对太阳能的利用率十分有限等。因此通过掺杂改性来提高纳米TiO2的光催化活性和可见光利用率已成为光催化研究领域的热点。此外，光催化剂在反应后难以分离回收也限制了其在实际当中的进一步应用。纳米纤维具有优异的物理（光、热、电、磁等）、化学特性，其较大的比表面积可使催化剂的表面能和光催化活性提高，另外纤维独特的形态使其具有耐流水冲击负荷的特点，有利于光催化剂在实际应用中的分离回收。本文采用溶胶凝胶法与静电纺丝相结合的技术制备了一维无机TiO2纳米纤维，在此基础上进行Y3+掺杂改性，得到了具有良好可见光催化活性的Y3+掺杂TiO2纳米纤维，并对光催化剂的结构、形貌、光吸收性能以及光催化活性进行了研究。
以钛酸四丁酯为前驱体，乙醇为溶剂，冰乙酸为催化剂采用溶胶-凝胶法制备出TiO2前驱体溶胶，使其粘度能够满足静电纺丝工艺的要求。以聚乙烯吡咯烷酮（PVP）为聚合物，通过电纺制得PVP/TiO2和Y3+掺杂PVP/TiO2有机纳米复合纤维，经高温热处理最终得到纯TiO2和一系列不同Y3+掺杂浓度的TiO2纳米纤维。运用差热-热重（TG-DSC）、X射线衍射（XRD）、傅立叶变换红外光谱（FTIR）、扫描电镜（SEM）、以及紫外-可见漫反射吸收光谱（UV-Vis）等分析手段对样品的结构、形貌以及光吸收性能进行了系统的表征。分析结果表明，实验制得的纳米纤维具有规则的一维结构和较大的长径比，表面形貌较好，TiO2纳米纤维平均直径为118±26 nm，Y3+掺杂TiO2纳米纤维平均直径为147±18 nm。TiO2晶粒的尺寸随着Y3+掺杂量的增加而减小，经Y3+掺杂后，TiO2的光吸收范围出现红移，对可见光有了明显吸收。
选用甲基橙为目标降解物，以日光灯为光源，对TiO2和Y3+掺杂TiO2的可见光催化性能进行了研究，考察了热处理温度以及Y3+掺杂浓度对光催化性能的影响，并对光催化剂的重复使用性能进行了测试。结果表明，在本实验中，当热处理温度为550 °C，Y3+掺杂浓度为1.5%时光催化剂活性最高，经4 h对甲基橙的降解率可达90.6%，重复使用5次以后降解率仍在80%以上。
对光催化剂的降解动力学进行了研究，分析结果表明纳米TiO2对甲基橙的可见光催化降解反应符合L-H一级反应动力学模型。

Semi-conductive catalysis has been widely used in air cleaning, water purification and antibacterial areas as a novel environment-friendly technology. Nano-titanium dioxide (nTiO2) is the most popular semi-conductive photo catalyst due to the high photochemical activity, bio- and chemo-inertness and anticorrosion behaviors. However, nTiO2 is confronted with such limitations as low photon efficiency and photocatalytic activity due to the rapid combination of electrons and holes. In addition, the absorption band of nTiO2 is located in ultraviolet region due to the wide forbidden band. Therefore, it is becoming a hot topic to exploit the ways to improve the photocatalytic activity of nTiO2 and the application efficiency of visible light. Nanofibers gave good physical and chemical properties and high specific surface area, resulting in high surface energy and photocatalytic activity. In addition, the fibrous feature makes it quite easy to recover the catalysts from solutions and suspensions. In this thesis one dimensional TiO2 naofibers were prepared by the use of electrospinning and sol-gel technologies. To achieve a better visible light catalytic activity, Y3+ was adopted into the TiO2 naofibers.
TiO2 sol-gel was obtained from butyl titanate as the precursor, ethanol as the solvent and ice acetic acid as the catalyst to ensure proper viscosity for electrospinning process. Polyvinyl pyrrolidone (PVP) fibers with entrapped TiO2 and Y3+ were prepared by blend electrospinning, followed by heat treatment to obtain Y3+ adopted TiO2fibers. The morphology, structure and photo-absorption profiles were characterized by thermogravity-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and ultraviolet-visible absorption spectroscope (UV-Vis). The obtained TiO2 nanofibers indicated an average diameter of 118 ± 26 nm, while that of Y3+-dopted TiO2 fibers of 147 ± 18 nm. The crystal size of TiO2 became smaller with the increase in the amount of Y3+ doped. A red shift of absorption band was found after Y3+ doping, resulting in apparent absorption in visible region.
The photocatalytic performance of TiO2 nanofibers and Y3+ adopted TiO2 nanofibers was determined on methyl orange under irradiation of a daylight lamp. The most significant degradation of methyl orange was found on TiO2 fibers doped by 1.5% Y3+ and heat-treated at 550 °C. Around 90.6% of methyl orange degradation was detected after 4 h irradiation and the degradation rates were maintained over 80% after repeat uses for 5 times. The photocatalytic dynamic study showed the degradation mechanism of Y3+-doped TiO2 nanofibers under visible region followed an L-H first order model.