Interfacial Synergy between Cu Nanoclusters and Oxygen Vacancies on CeO2 for Enhanced Selective Photoreduction of CO2 to C2H4

Abstract

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. OVs 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 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.