Study on the photocatalytic activities of TiO2 thin films prepared by sol-gel dip-coating method and hydrothermal method

• Main Authors: LIN, ZHEN-YU, 林震宇
• Other Authors: LI, KUN-DAR
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/96974380843530629064

碩士 === 國立臺南大學 === 材料科學系碩士班 === 105 === TiO2 is one of the most used functional materials for advanced applications. In many studies, TiO2 had been applied to produce self-cleaning windows because of its superior photocatalytic ability and the transparent property of thin films. In this study, TiO2 seed layers on the Si(100) substrate were first prepared by dip-coating method. To increase the crystallinity of TiO2 seed layers, multiple times of dip-coating and heat treatment were utilized. Then, the hydrothermal process was implemented to grow TiO2 nanorods array at 180oC for 2 hours. Finally, the post-heat treatment was applied again on TiO2 nanorods array. The properties of TiO2 seed layers and nanorods array were characterized, and the influence of heat treatment with different parameters on the photocatalytic properties of TiO2 seed layers and nanorods array were also analyzed. The results showed that the crystallinity of TiO2 seed layers was increased with the thickness of thin films. From SEM analysis, it can be found that the TiO2 seed layers coated on the substrate surface were uniform. However, while the TiO2 seed layers were getting too thick, the cracks would appear on the surface of TiO2 films. With the heat treatment at a high temperature, the growth of the TiO2 seed layers was observed, and the crystallinity of the films would be improved. In the experiments of the hydrothermal method, various concentrations of HCl were used to control the morphologies of the TiO2 thin films by virtue of the inhibition of TiO2 hydrolysis in the solution. In SEM images, it was observed that the rectangle shape of TiO2 columns would form in the hydrothermal treatment with high HCl concentration and a flower-like morphology of TiO2 developed in a low HCl concentration. According to the experimental results, the best degradation of the methyl blue solution happened in the 3 layers of TiO2 seed layer. The photocatalytic activity of TiO2 was reduced after the hydrothermal treatment. To improve the photocatalytic properties of TiO2 thin films, a post-heat treatment on TiO2 thin films would be necessary after the hydrothermal treatment.