Insight into the function of noble-metal free Cu₃P decorated Zn_0.5Cd_0.5S for enhanced photocatalytic hydrogen evolution under visible light irradiation– mechanism for continuous increasing activity

The development of low-cost photocatalysts for highly efficient and durable photocatalytic H₂ evolution under visible light is of great challenge. In present study, a Z-scheme Cu₃P/Zn_0.5Cd_0.5S is fabricated via in-situ phosphidation method for efficient visible-light-driven H₂ evolution. The wide light absorption property of Cu₃P enhances the visible light absorption of Cu₃P/Zn_0.5Cd_0.5S. The electrical conductivity of metallic Cu₃P and the Z-scheme constructure of Cu₃P/Zn_0.5Cd_0.5S accelerate electron transport rate. The Cu₃P/Zn_0.5Cd_0.5S catalyst achieves highest hydrogen evolution rate of 2.7 mmol g⁻¹ h⁻¹, which is 3.1 folds higher than that of pristine Zn_0.5Cd_0.5S. More interestingly, the Cu₃P/Zn_0.5Cd_0.5S exhibited increasing H₂ production during reaction. The further reduction of PO₃³⁻→P^&− and the further formation of Cu₃P is determined to be the key reason for increasing activity. Besides, Cu₃P/Zn_0.5Cd_0.5S prepared by in-situ phosphidation method shows much better catalyst property and performance than that prepared by afterwards mixing method, and the possible reasons for such difference is proposed in present study.