In-situ construction of N-doped Zn_0.6Cd_0.4S/oxygen vacancy-rich WO₃ Z-scheme heterojunction compound for boosting photocatalytic hydrogen production

Photocatalytic water splitting technology for H₂ production represents a promising and sustainable approach to clean energy generation. In this study, a high concentration of oxygen vacancies was introduced into tungsten trioxide (WO₃) to create a vacancy-rich layer. This modified WO₃ (WO_3-x) was then combined with N-doped Zn_0.6Cd_0.4S through a hydrothermal synthesis, resulting in the formation of a Z-scheme heterojunction composite aimed at enhancing photocatalytic performance. Under visible light, the H₂ production activity of the composite reached an impressive 8.52 mmol·g^-1 without adding co-catalyst Pt. This corresponds to enhancements of 7.82 and 4.39 times the production yield of pure ZCS and ZCSN, respectively. However, the hydrogen production increased to 21.98 mmol·g^-1 when Pt was added as a co-catalyst. Furthermore, an array of characterizations were employed to elucidate the presence of oxygen vacancies and the establishment of the Z-scheme heterojunction. This structural enhancement significantly facilitates the utilization of photo-generated electrons while effectively preventing photo-corrosion of ZCSN, thus improving material stability. Our study provides a new scheme for the incorporation of oxygen-rich vacancy and the construction of Z-scheme heterojunction, demonstrating a synergistic effect that greatly advances photocatalytic performance.