2D/2D Heterostructured CdS/WS₂ with Efficient Charge Separation Improving H₂ Evolution under Visible Light Irradiation

Abstract

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