Interfacial synergy between Cu nanoclusters and oxygen vacancies on CeO₂ for enhanced selective photoreduction of CO₂ to C₂H₄

The construction of photocatalysts with high C-C coupling selectivity is important for achieving high value conversion of CO₂. This study developed a synergistically modulated Cu@CeO₂-OVs photocatalytic system through controlled deposition of sub-nanometer Cu clusters on CeO₂ supports with abundant oxygen vacancies (OVs). The structural and photoelectronic characterisation of the system shows that the Cu clusters are highly dispersed and form a stable interface with the CeO₂ surface. OV introduction induces significant modulation of the material's electronic configuration and surface adsorption behavior, resulting in a synergistic enhancement of the light absorption capacity, carrier separation efficiency and interfacial charge transport properties. The Cu@CeO₂-OVs exhibited excellent photocatalytic C₂H₄ generation under a CO₂ atmosphere and simulated solar illumination conditions with yields up to 31.4 μmol g⁻¹ h⁻¹ with promising stability and reproducibility. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) demonstrated the system's exceptional ability to stabilize key intermediates (CO, COOH, OCCO, and OCCH₂), confirming its effectiveness in promoting the C-C coupling pathway. As confirmed by Density Functional Theory (DFT), the Cu-OVs synergistic effect dramatically lowers the free energy barriers for CO production and coupling steps, resulting in superior C₂ product selectivity. In this work, a synergistic construction strategy between metal clusters and defect interfaces is proposed, establishing mechanistic principles and practical approaches for controlling CO₂ photoreduction toward selective multicarbon formation.