2D/3D S-Scheme Heterojunction Interface of CeO₂-Cu₂O Promotes Ordered Charge Transfer for Efficient Photocatalytic Hydrogen Evolution

Rapid intrinsic carrier recombination severely restricts the photocatalytic activity of CeO2-based catalytic materials. In this study, a heterogeneous interfacial engineering strategy is proposed to rationally perform interface modulation. A 2D/3D S-scheme heterojunction with strong electronic interactions was constructed. A composite photocatalyst was synthesized for the 3D Cu₂O particles anchored at the edge of 2D CeO₂. First-principles calculations (based on density functional theory) and the experimental results show that a strongly coupled S-scheme heterojunction electron transport interface is formed between CeO₂ and Cu₂O, resulting in efficient carrier separation and transfer. The photocatalytic hydrogen evolution activity of the composite catalyst is significantly improved in the system with triethanolamine as the sacrificial agent and is 48 times as that of CeO₂. In addition, the resulting CeO₂-Cu₂O photocatalyst affords highly stable photocatalytic hydrogen activity. This provides a general technique for constructing unique interfaces in novel nanocomposite structures.