2D/2D Heterostructured CdS/WS₂ with Efficient\nCharge Separation Improving H₂ Evolution under Visible\nLight Irradiation

Abstract

Efficient\nwater splitting for H₂ evolution under visible light irradiation\nhas attracted more attention for solving the global environmental\nand energy issues, but it is still a major challenge to develop an\nearth-abundant and efficient photocatalyst. Herein, we report two-dimensional\n(2D)/2D heterostructured CdS/WS₂ (CdS/WS₂),\ncomposed of nanosheet CdS (CdS) and nanosheet WS₂ (WS₂), as an efficient photocatalyst for H₂ evolution.\nAs a noble metal-free visible light-driven catalyst for H₂ evolution, CdS/WS₂ with 10 wt % WS₂ exhibited\nthe largest H₂ evolution rate of 14.1 mmol g^–1 h^–1 under visible light irradiation to be 8 times\nlarger than that of pure CdS. The lifetime and dynamics of photogenerated\nelectrons were evaluated by femtosecond time-resolved diffuse reflectance\nspectroscopy, indicating that WS₂ works as an electron-trapping\nsite and a cocatalyst to cause H₂ evolution under visible\nlight irradiation. This work suggests that CdS/WS₂ has\ngreat potential as a low-cost and highly efficient photocatalyst for\nwater splitting.