Cu3MS4 (M=V, Nb, Ta) and its Solid Solutions with Sulvanite Structure for Photocatalytic and Photoelectrochemical H2 Evolution under Visible‐Light Irradiation

Abstract Solid solutions with of Cu 3 VS 4 with either Cu 3 NbS 4 or Cu 3 TaS 4 (Cu 3 Nb 1− x V x S 4 or Cu 3 Ta 1− x V x S 4 ) were prepared by a solid‐state reaction and adopted a sulvanite structure. Their band gaps were 1.6–1.7 eV corresponding to the absorption of a wide range of visible light. Ru cocatalyst‐loaded Cu 3 MS 4 (M=V, Nb, Ta), Cu 3 Nb 1− x V x S 4 , and Cu 3 Ta 1− x V x S 4 showed photocatalytic activities for sacrificial H 2 evolution under visible‐light irradiation. Most solid solutions showed better activities than the single‐component Cu 3 MS 4 (M=V, Nb, Ta). Cu 3 MS 4 (M=V, Nb), Cu 3 Nb 1− x V x S 4 , and Cu 3 Ta 1− x V x S 4 also functioned as photoelectrodes and gave cathodic photocurrents under visible‐light irradiation, indicating a p‐type semiconductor character. Cu 3 Nb 0.9 V 0.1 S 4 showed the best photocatalytic and photoelectrochemical performances. When Ru‐loaded Cu 3 Nb 0.9 V 0.1 S 4 was used as a photocathode with a CoO x ‐loaded BiVO 4 photoanode, photoelectrochemical water splitting proceeded under simulated sunlight irradiation without an external bias.