Effect of surface defect of titanium dioxide on photocatalytic activity for water decomposition to hydrogen

Abstract

Effects of TiO₂ surface defects on photocatalytic activity for water decomposition to hydrogen are also investigated. Nanocrystalline titanium dioxide was prepared using the solvothermal method. Obtained titanium dioxide powder was treated to modify the surface properties by quenching in various media. For quenching in liquid phase medias, water at room temperature and 373 K, hydrogen peroxide at room temperature and 373 K were selected. For quenching in gas phase media, air at room temperature, 373 K and 77 K were selected. It is also found that quenching titanium dioxide catalysts in various media is not significantly differences in the crystallites size and BET surface area, but it is also found that quenching immediately after calcined was increasing amount of Ti³⁺ on surface of catalyst and exhibited increasing photocatalytic activity. Quenching in a similar medium, TiO₂ quenched in cooler media exhibited higher photocatalytic activity than those quenched in hotter ones. For room temperature quenching, the photocatalytic activities of TiO₂ quenched in air exhibited higher activity than those quenched in 30 %wt H₂O₂ and H₂O, respectively. There were observed that start of the reaction because of bridging hydroxyl group and water on the TiO₂ surface.