The gel-derived TiO2 and P-TiO2 transparent films coated on fused-SiO2 substrates were prepared using a spin-coating technique. Effects of phosphorus dopants and calcination temperature on crystal structure, crystallite size, microstructure, light transmittance, and photocatalytic activity of the films were investigated. By introducing P atoms to Ti-O framework, the anatase crystal structure of TiO2 in the film was maintained up to temperatures as high as 900 ˚C and the growth of anatase crystallites was hindered. The photocatalytic activities of the prepared films were characterized using the characteristic time constant (τ) for the photocatalytic reaction. The titania film with smaller τ possesses higher photocatalytic ability. The P-TiO2 films calcined at 600 - 900 ˚C can photocatalytically decomposed ≧ 84 mol% of the methylene blue (the corresponding τ ≦ 7.1 h) after exposing to 365-nm UV light for 12 h, which were better than the pure TiO2 films prepared at the same calcination temperature.
