Characterization of a TiO2 photocatalyst film deposited by CVD and its photocatalytic activity

TiO2 photocatalyst films were prepared by low-pressure metal-organic (LPMO) CVD, with varying reaction temperatures and deposition times, using titanium tetra-isopropoxide (TTIP). Firstly, the characteristics of the CVD preparation of TiO2 films, as a function of the CVD reaction temperature and deposition time, were studied experimentally. Secondly, the photocatalytic activities of TiO2 films were evaluated by the decomposition rate of methylene blue in aqueous solution using a photo-reactor. The results indicated that film thickness was linearly proportional to the deposition time. The structure of the film was strongly dependent on the reaction temperature and deposition time. Of the TiO2 films grown, anatase and futile showed the highest photocatalytic activity, whereas the amorphous TiO2 films showed lower activities. The photocatalytic activity strongly depended on the film deposition time (or film thickness), but this was nonlinear. The optimum thickness of the TiO2 catalyst film grown by LPMOCVD is located between 3 mu m and 5 mu m.