Photo-Generated Activities of Nanocrystalline TiO2 Thin Films

Transparent nanocrystalline TiO 2 thin films with high photocatalytic activity and photo-induced wettability were successfully deposited on a glass slide. Crystal phase transformations and particle size of TiO 2 were investigated. Structural and morphological properties of the films were investigated. The photocatalytic activity of the TiO 2 films was evaluated. It is found that the photocatalytic activity of TiO 2 thin films is significantly decreased by increasing the annealing temperature, which results in a decrease in BET surface area and an increase in crystal size. In addition, increasing film thickness within a certain range significantly improves the photocatalytic activity without causing crack formation of the TiO 2 films. Photocatalytic oxidation and photo-induced wettability conversion on the films were investigated. It is found that photo-induced hydrophilic conversion is observed even on the samples annealed at high temperature. The best photo-generated activities are obtained by optimization of dip-coating cycles and annealing temperatures.