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

Abstract

The photocatalytic degradation activity of visible-light-responsive TiO2, which was developed as oxygen-deficient TiO2, was improved by pretreatment with UV-light irradiation in the presence of oxygen and adsorbed water. The C2H2 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 C2H2. 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.