Visible-Light-Response and Photocatalytic Activities of TiO2 and SrTiO3 Photocatalysts Codoped with Antimony and Chromium

TiO 2 and SrTiO 3 codoped with antimony and chromium showed intense absorption bands in the visible light region and possessed 2.2 and 2.4 eV of energy gaps, respectively. TiO 2 codoped with antimony and chromium evolved O 2 from an aqueous silver nitrate solution under visible light irradiation, while SrTiO 3 codoped with antimony and chromium evolved H 2 from an aqueous methanol solution. The activity of TiO 2 photocatalyst codoped with antimony and chromium was remarkably higher than that of TiO 2 doped with only chromium. It was due to that the charge balance was kept by codoping of Sb 5+ and Cr 3+ ions, resulting in the suppression of formation of Cr 6+ ions and oxygen defects in the lattice which should work as effectively nonradiative recombination centers between photogenerated electrons and holes.