Comparison of visible-light-driven routes of anion-doped TiO2 and composite photocatalyst

This study investigates and compares the efficiency of visible-light-driven routes of anion-doped TiO2 and composite photocatalyst by using preparation conditions as controls for crystal phase, crystallite size, and optical properties. Anion-doped TiO2 was formed by doping nitrogen, and the composite photocatalyst was made from TiO2 combined with Multi-Walled Carbon Nanotubes (MWCNTs) via the sol-gel process. The results of the evaluated performances of the photocatalysts with the photodegradation of methanol under visible-light radiation demonstrated that the anion-doped TiO2 exhibited higher photocatalytic activity than that of the composite photocatalyst. It is concluded that the composite photocatalyst was induced into the visible-light region by the photosensitizer, which may decrease the efficiency of electron transfers between photosensitizer and TiO2 phases, or that photosensitizer could not effectively induce the valance band electron of TiO2 into photosensitizer to form positive holes. On the other hand, the anion-doped TiO2 directly formed a new energy band gap, which indicates a superior route to visible-light response. (C)2009 The Ceramic Society of Japan. All rights reserved.