Synergistic Ce-ZnIn₂S₄/ZnS S-scheme heterojunction via a one-step method for efficient CO₂ photoreduction

Solar-powered photocatalytic CO₂ reduction represents a promising strategy for achieving carbon neutrality through sustainable solar-to-chemical energy conversion. Nevertheless, inefficient charge separation and sluggish interfacial reaction kinetics markedly limit its performance. Herein, Ce-regulated ZnIn₂S₄/ZnS S-scheme heterojunctions were synthesized via a facile one-step in situ hydrothermal strategy to regulate interfacial charge transfer and surface reaction processes. The ZnIn₂S₄/ZnS interface establishes an S-scheme charge-migration pathway, facilitating directional migration and utilization of photogenerated carriers, while Ce incorporation induces electronic redistribution and modulates the local electronic environment. Experimental investigations combined with theoretical calculations reveal that Ce-mediated electronic modulation cooperates with the S-scheme heterointerface to strengthen CO₂ adsorption, accelerate interfacial charge transfer, and reduce the energy barrier of CO₂ reduction. Benefiting from this synergistic electronic regulation, the optimized C2ZZ2 catalyst achieves a CO evolution rate of 140.6 μmol g^-1 h^-1, approximately 4.5-fold higher than pristine ZnIn₂S₄. This work provides mechanistic insights into rare-earth-mediated electronic regulation in metal sulfide photocatalysts, offering a deeper understanding of the relationship among electronic modulation, interfacial charge-transfer dynamics, and CO₂ reduction kinetics.