Covalent-Coupled Zn0.4Cd0.6S with g-C3N4 as a Sheet-on-Sheet Z-Scheme Photocatalyst for Water Splitting

Development of heterojunction to improve charge separation efficiency is one of the main strategies to enhance the hydrogen production performance of photocatalysts. Herein, we fabricate a 2D/2D Z-scheme heterojunction-coupled Zn0.4Cd0.6S with g-C3N4 by in situ hydrothermal approach. The sheet-on-sheet architecture provides full contact of heterojunction to accelerate interfacial charge transfer and increase surface-active sites. Additionally, the Zn–N coordination bond acts as a strong interfacial interaction between Zn0.4Cd0.6S and g-C3N4, and photogenerated charges are spatially separated along the Z-scheme mechanism. In particular, under visible-light (λ ≥ 420 nm) irradiation, the optimal photocatalyst exhibits a high hydrogen production (H2 production rates: 7.69 mmol g–1 h–1) without any cocatalysts, 4 times higher than that of the g-C3N4 photocatalyst using Pt as a cocatalyst. The catalyst has a long-term stability of up to 50 h. Therefore, a direct Z-scheme heterojunction with intimate contact and a well-definite bridging chemical bond could be a prospective photocatalyst for hydrogen generation.