Photocatalytic properties of lanthanide tungstates Ln2W2O9 (Ln=La, Pr, Nd, Sm, and Gd)

Lanthanide tungstates, Ln2W2O9 (Ln=La, Pr, Nd, Sm, and Gd), were prepared via the polymerized complex method at 1273 K for 2 h, and their photocatalytic activities for hydrogen and oxygen evolution were investigated. Pt-loaded Gd2W2O9 exhibited activity for H2 evolution from an aqueous methanol solution under light irradiation (λ>300 nm). The remaining Ln2W2O9 were inactive for H2 evolution due to the influence of the Ln elements and their crystal structures. All Ln2W2O9 were inactive for O2 evolution from an aqueous AgNO3 solution due to the lack of O2 evolution sites on the surface.