Hydrogen Reduced Rutile Titanium Dioxide Photocatalyst

For TiO2 photocatalysts, recombination of photoexcited electrons and holes would occur in crystalline defects such as oxygen vacancies, Ti ions, and surface states. Therefore, it is believed that the density of crystalline defects should be decreased to improve the photocatalytic activity of TiO2 particles. Contrary to this common knowledge, the introduction of crystalline defects by hydrogen reduction treatment is shown to increase the lifetime of photoexcited electrons in rutile TiO2 photocatalysts with an increase of n-type electrical conductivity. The photocatalytic activities of H2-reduced rutile TiO2 were higher than those of anatase TiO2 and mixed-phase TiO2. This chapter explains the effect of donor doping on the photocatalytic activity of rutile TiO2, the relationship between its physicochemical properties and photocatalytic performances, and the mechanism of the enhanced activity of H2-reduced TiO2. Particle size dependence on the enhanced activities suggests the formation of a space charge layer in large TiO2 crystallites.