Improvement of Photocatalytic Degradation Activity of Visible-Light-Responsive TiO2 by Aid of Ultraviolet-Light Pretreatment

The photocatalytic degradation activity of visible-light-responsive TiO 2, which was developed as oxygen-deficient TiO 2, was improved by pretreatment with UV-light irradiation in the presence of oxygen and adsorbed water. The C 2 H 2 degradation rate under visible light was increased up to twice by the UV pretreatment. During the UV pretreatment, peroxo species was produced on the surface, and the visible-light absorbance of the photocatalyst between 400 and 500 nm was increased. The modification of the surface accompanied by the formation of peroxo species seems to enhance the photocatalytic oxidation of C 2 H 2 . The increased activity was gradually diminished within 24 h under dark condition, suggesting that the modified surface is metastable and is reverted to the original surface.