Study On Photoelectrocatalytic Performances Of Metal Doped TiO₂ Nanotube Arrays And TiO₂ Nanofibers By Hydrothermal Method

Titanium dioxide (TiO2) with nanostructure has been studied as photocatalyst in degradation of organic pollutants for decades. TiO2 nanotube arrays prepared by anodization method possess great specific surface area, prominent absorption ability and strong mechanical strength, thus exhibit better PC performance and higher photoelectron conversion efficiency than TiO2 nano film. However, it is very important to further improve its photocatalytic activity by reasonable doping. It has been proved that metal doping would be a viable way to improve the photocatalytic activity of TiO2. In the present work, Au nanocrystal anchored TiO2 nanotube array electrode and iron doped TiO2 nanotube array electrode were prepared and characterized. In addition, to realize the industrialization of nano TiO2, TiO2 nanofibers prepared by hydrothermal method were studied and characterized. Based on the mentioned above, some works were carried out as follows:(1) Au nanocrystal anchored TiO2 nanotube array electrode was prepared by electrochemical self-doping method. The electrodes presented compact array configuration with an average pore diameter of approximately 100 nm and a length approximately 7μm. Au nanocrystal anchored TiO2 nanotube array electrode analyzed by X-ray fluorescence spectroscopy (XRF) were 0.05wt.%. X-ray spectra (XRD) indicated that the crystal structure of Au/TiO2 electrode prepared at 500℃was pure anatase phase. UV-vis absorption spectra (DRS) showed a broad absorption band in the 400nm-700nm region because of plasma resonance absorption of ultrafine Au nanocrystal. Under visible light irradiation, the photodegradation of methylene blue (MB, 10ppm) on Au/TiO2 electrode was more than 85% in 6h.(2) Fe-doped TiO2 nanotube array electrode was prepared by immersing TiO2 nanotube array in iron salt solution under ultrasonic condition. The DRS and SPV analysis showed noticeable increase of visible light absorption and excellent separation of ability of electron-hole pair of Fe-doped TiO2 nanotube array electrode. Under UV light irradiation, the photodegradation of MB (10ppm) on Fe/TiO2 electrode was more than 90% in 2 h, while visible light irradiation,40% photodegradation efficiency was obtained in 6h. Fe-doped TiO2 nanotube array electrode exhibited excellent photocatalytic activity, but excess iron doping, its photocatalytic activity was decreased. (3) TiO2 nanofibers with diameter of approximately 50nm and length of approximately 20um were prepared by hydrothermal method. During the process of acid washing and calcination, the structure of nanofibers was not damaged. After 300-450℃calcination, they were anatase phase. Under UV light irradiation, the photodegradation of MB was 90% in 80min.