Photocatalytic hydrogen and oxygen formation over SiO2-supported RuS2 in the presence of sacrificial donor and acceptor Original Research Article

Photocatalytic activities of ruthenium disulfide (RuS2) non-supported, SiO2 and TiO2-supported semiconductor photocatalysts for hydrogen and oxygen formation from water were studied. Hydrogen and oxygen were produced, respectively, over SiO2-supported RuS2 (band gap: 2.3 eV) catalysts under UV light (>300 nm) and visible light (>400 nm) irradiation in the presence of a sacrificial electron donor and acceptor. Photocatalytic activities for hydrogen and oxygen formation increased remarkably due to support on SiO2. Under UV light irradiation for 46 h, 213 μmol of hydrogen, which is nine times the amount of RuS2 supported, was produced on 1 wt.% RuS2/SiO2 in the Na2S/Na2SO3 solution. The oxygen yield for 26 h in an AgNO3 solution was 121 μmol. Photocatalytic activity for oxygen formation under visible light irradiation was almost the same as that under UV irradiation. No enhancement effect of gas evolution by Pt catalyst loading was observed. Remarkable enhancements of photocatalytic activity for hydrogen and oxygen formation due to support on TiO2 were also observed, suggesting the presence of a charge transfer process between two semiconductor particles.