The chemical states and properties of doped TiO2 film photocatalyst prepared using the Sol-Gel method with TiCl4 as a precursor

TiO2 film was deposited on the silicon wafer using a Sol-Gel method with TiCl4 as a precursor. The TiO2 film with anatase structure was formed after annealed above 350 degrees C for 1 h in air. The thickness of the film was about 167 nm for one coating. There was a very slight interface diffusion between TiO2 layer and Si substrate during annealing treatment, and no chemical reaction was detected. After annealed at 400 degrees C for 1 h in air, the dopants of Pt and Pd existed as metallic Pt and PdO in TiO2 film, respectively. After the films were reduced using H-2 in 400 degrees C for 2 h Pt existed as aggregated metallic Pt particles, while Pd existed as highly dispersed metallic Pd particles. The absorption intensity for UV and visual light can be intensified significantly, and the main absorption peak can be shifted to a higher wave number after the TiO2 film doped with Pd was reduced with H-2. This resulted from the interaction between highly dispersed Pd and the TiO2 film. Pd atoms entered into the lattice of anatase TiO2 film. The reduction of TiO2 film doped with Pt cannot change the UV absorption due to the weak interaction between Pt and TiO2. (C) 2000 Elsevier Science B.V. All rights reserved.