The effect of co-catalyst for Z-scheme photocatalysis systems with an Fe3+/Fe2+ electron mediator on overall water splitting under visible light irradiation

Co-catalysts loaded on SrTiO3:Rh in visible-light-driven Z-scheme photocatalysis systems consisting of SrTiO3:Rh for H-2 evolution, BiVO4 for O-2 evolution, and Fe3+/Fe2+ for an electron mediator were investigated. The activity of the system using a Ru co-catalyst for overall water splitting was as high as that of the system using a t co-catalyst. The photocatalytic activity of the system using the Pt co-catalyst decreased as the partial pressures of evolved H-2 and O-2 were increased. In contrast, such deactivation was not observed for the system using the Ru CO-catalyst. The investigation of the back-reactions revealed that water formation from H-2 and O-2, reduction of Fe3+ by H-2, and oxidation of Fe2+ by O-2 were significantly suppressed in the system using the Ru co-catalyst, resulting in good pholocatalytic performance for water splitting. The (Ru/SrTiO3:Rh)-(BiVO4)-(Fe3+/Fe2+) photocatalysis system gave a quantum yield of 0.3% and a stable activity more than 70 h. This system was confirmed to be active for water Splitting using a solar simulator. (c) 2008 Elsevier Inc. All rights reserved.