Structural Analysis on Photocatalytic Efficiency of TiO₂by Chemical Vapor Deposition

Structural analysis of anatase TiO 2 films on window glass by chemical vapor deposition (CVD) was performed. Relationships between preferred orientation and photocatalytic activity of polycrystalline TiO 2 films were investigated. Photocatalytic activity was affected by crystalline orientation that depended on the deposition temperature. <112>-oriented TiO 2 films were obtained at 360°C, while <001>-oriented films were obtained at other temperatures. Photocatalytic activity of the <112>-oriented film was greater than that of the <001>-oriented film. The film with <112>-preferred orientation exhibited a columnar structure resulting in a larger surface area for photocatalytic reaction than the films with <001>-preferred orientation. Also, the film with <112>-preferred orientation exhibited a facet consisting of s-faces {100} which showed the larger surface energy theoretically. It is clear that fabrication of the thin film TiO 2 by CVD should be controlled to exhibit the <112>-preferred orientation for the optimum photocatalytic efficiency.