Photocatalytic Water Splitting into H2 and O2 over R3TaO7 and R3NbO7 (R = Y, Yb, Gd, La): Effect of Crystal Structure on Photocatalytic Activity

Abstract

The photocatalytic activities of R3TaO7 and R3NbO7 (R = rare earthY, Yb, Gd, or La) were strongly dependent on the crystal structure. Photocatalytic splitting of pure water into H2 and O2 proceeded over NiOx-loaded La3TaO7 and La3NbO7 photocatalysts with weberite-orthorhombic structure, while only a small amount of H2 was evolved over other photocatalysts with cubic structure. In the case of the La3TaO7 and La3NbO7 photocatalyst, the phase transition from cubic into orthorhombic was observed at 1000−1050 °C, and the photocatalytic activity was drastically increased by phase transition from cubic into orthorhombic.