Preparation Of Vertical Orientation TiO₂Array Film By Hydrothermal

Wide band gap metal oxide semiconductor, such as TiO2, SnO2, Fe2O3, with good gas sensitivities, received extensive attention. Among them, Titanium oxide (TiO2) is the hot research point due to its advantages of low working temperature, high sensitivity and simple for fabrication. Anodization is the main method to form TiO2nanotubes with large specific surface area, which is important to improve the sensitivity for the application in gas sensor. In recent years, rutile TiO2nano-array thin films based on an FTO substrate were successful fabricated by hydrothermal method. For further improve the gas sensitivity of the thin film, it is important to explore the preparation condition of the anatase TiO2nano-array thin films.In this thesis, hydrothermal method is employed to synthesis TiO2nano-array thin film. The effects of the preparation conditions, such as reaction temperature and time, the concentration of ethanol and H+ions, the ratio of HCl and H2SO4, on the phase selection and orientation growth is systematically studied. The pure rutile film with (002) orientation growth, pure anatase film with (004) orientation growth, or a mixed phase thin film are successfully fabricated and the corresponding preparation conditions are determined. According to the X-ray diffraction studies on the thin films obtained at various reaction times, the growth mechanisms of the anatase nano-array thin films are obtained. Finally, the measurement of H2gas sensitivity of the anatase film shows a good gas-sensing property, indicating its excellent application in gas sensor.