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 H 2 and O 2 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 / NaTaO 3 doped with La showed the highest activity. Some metal sulfide photocatalysts such as AgGaS 2 and AgInZn 7 S 9 showed high activities for H 2 evolution from aqueous solutions containing S 2 - and SO 3 2 - as electron donors under visible light irradiation ( wavelength > 420 nm ) . The H 2 evolution was observed even under irradiation using a solar simulator. Pt / SrTiO 3 doped with Rh has also arisen as a novel oxide photocatalyst for H 2 evolution from aqueous solutions containing reducing reagents under visible light irradiation. On the other hand, BiVO 4 and AgNbO 3 showed high activities for O 2 evolution in the presence of sacrificial reagent ( Ag + ) under visible light irradiation.