Structural analysis on photocatalytic efficiency of TiO2 by chemical vapor deposition

Abstract

Structural analysis of anatase TiO2 films on window glass by chemical vapor deposition (CVD) was performed. Relationships between preferred orientation and photocatalytic activity of polycrystalline TiO2 films were investigated. Photocatalytic activity was affected by crystalline orientation that depended on the deposition temperature. <112>-oriented TiO2 Films were obtained at 360degreesC, 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 TiO2 by CVD should be controlled to exhibit the <112>-preferred orientation for the optimum photocatalytic efficiency.