Photocatalytic Activity of R3MO7 and R2Ti2O7 (R = Y, Gd, La; M = Nb, Ta) for Water Splitting into H2 and O2

Abstract

The photocatalytic activities of R₃MO₇ and R₂Ti₂O₇ (R = Y, Gd, La; M = Nb, Ta) strongly depended on the crystal structure. Overall, photocatalytic water splitting into H₂ and O₂ proceeded over La₃TaO₇ and La₃NbO₇, which have an orthorhombic weberite structure, Y₂Ti₂O₇ and Gd₂Ti₂O₇, which have a cubic pyrochlore structure, and La₂Ti₂O₇, which has a monoclinic perovskite structure. All of these materials are composed of a network of corner-shared octahedral units of metal cations (TaO₆, NbO₆, or TiO₆); materials without such a network were inactive. The octahedral network certainly increased the mobility of electrons and holes, thereby enhancing photocatalytic activity.