Development of photocatalyst materials for water splitting

Various photocatalyst materials developed by the group of the author are described. Alkali and alkaline earth tantalates have arisen as a new group of photocatalyst materials for water splitting into H2H2 and O2O2 under ultraviolet light irradiation. They showed the activities even without co-catalysts such as Pt, being different from titanate photocatalysts. When NiO co-catalysts were loaded on the tantalate photocatalysts, the photocatalytic activities were drastically increased. Among the tantalates, NiO/NaTaO3NiO/NaTaO3 doped with La showed the highest activity. Some metal sulfide photocatalysts such as AgGaS2AgGaS2 and AgInZn7S9AgInZn7S9 showed high activities for H2H2 evolution from aqueous solutions containing S2-S2- and SO32- as electron donors under visible light irradiation (wavelength>420nm). The H2H2 evolution was observed even under irradiation using a solar simulator. Pt/SrTiO3Pt/SrTiO3 doped with Rh has also arisen as a novel oxide photocatalyst for H2H2 evolution from aqueous solutions containing reducing reagents under visible light irradiation. On the other hand, BiVO4BiVO4 and AgNbO3AgNbO3 showed high activities for O2O2 evolution in the presence of sacrificial reagent (Ag+)(Ag+) under visible light irradiation.