Photocatalytic water splitting of La2AlTaO7 and the effect of aluminum on the electronic structure

A new photocatalyst La2AlTaO7 with orthorhombic structure was synthesized by the solid-state reaction method. The formation rate of H-2 evolution from CH3OH/H2O solution under the irradiation of a 350 W high-pressure Hg lamp is about 108.9 mu mol h(-1) for La2AlTaO7 (0.1 g). It also showed activity leading to the decomposition of pure water into H-2 and O-2 even in the absence of co-catalysts under UV light irradiation. The photocatalyst loaded with 0.2 wt% NiO co-catalyst was found to have the highest activity. It was found from the electronic band structure study, using the density functional theory (DFT) with plane-wave basis, that the valence band top mainly consists of O 2p orbitals and the conduction band bottom is mainly constructed of Al 3s3p. The effect of aluminum on electronic structure was discussed in close connection with the UV-vis absorption spectrum. (C) 2008 Elsevier Ltd. All rights reserved