ZnSe nanoparticles with bulk WC as cocatalyst: A novel and noble-metal-free heterojunction photocatalyst for enhancing photocatalytic hydrogen evolution under visible light irradiation

Abstract

The exploration of inexpensive and stable semiconductor photocatalysts are extremely urgent for obtaining sustainable hydrogen (H2) energy by photocatalytic water splitting. Herein, a novel and noble-metal-free heterojunction photocatalyst, which is ZnSe nanoparticles (NPs) deposited on the surface of bulk WC, was successfully fabricated via one-pot solvothermal method. The photocatalytic results indicated that ZnSe is a great potential photocatalyst for the reduction of water to H2. Meanwhile, as a replacement of noble-metal cocatalyst, bulk WC could remarkably improve the photocatalytic H2 evolution activity of ZnSe NPs under visible light irradiation in the heterojunction system. The H2 evolution of the optimal sample achieved 2978.31 μmol g−1 in 5 h, which was 5.4 times higher than that of ZnSe NPs. The observably boosted H2 generation activity could be ascribed to the ample reactive sites and the broadened visible-light absorption. Moreover, intimate interfacial contact between ZnSe NPs and bulk WC engenders synergetic effect and Schottky junction. Electrochemical, steady-state and time-resolved PL measurements further confirmed that the novel heterojunction photocatalyst could effectively accelerate the separation of charge carriers, decrease the overpotential and prolong the lifetime of photoinduced electrons. This study provides a novel and cost-effective approach for designing efficient noble-metal-free photocatalysts and improving H2 evolution activity of selenides under visible-light-driven photocatalytic water splitting.