Boosting CO₂ Electroreduction to Multi-carbon Products via Oxygen-rich Vacancies and Ce⁴⁺-O^2--Cu⁺ Structure in Cu/CeO₂ for Stabilizing Cu⁺

Cu is a promising electrocatalyst for the CO2 reduction reaction (CO2RR) to produce high-value C2+ products. Due to the fierce competition of the hydrogen evolution reaction, the slow diffusion of CO2, and the high energy barrier of the C C coupling reaction, it is still challenging to achieve high activity and high selectivity to produce multi-carbon products on copper-based electrocatalysts. In this work, we synthesized Cu/ CeO2 catalysts with varying amounts of Cu doping, aiming at effectively converting CO2 into C2+ products through electroreduction. At a copper doping level of 9.77 wt%, the catalyst exhibited a current density of 16.8 mAcm 2 using a standard H- type cell, achieving a C2+ faradaic efficiency (FE) of 78.3%. Through additional experiments and material characterization, we confirmed that controlling the Cu loading on the surface of CeO2 is an effective way to regulate the ratio of Cu+ to Cu0 active sites and the number of oxygen vacancies. Furthermore, the strong electron interaction between Ce-4+ O-2 Cu+ structure can stabilize Cu+ species and enhance the overall stability of the catalyst. This strategy enhances the selectivity towards C2+ products and effectively suppresses the competing hydrogen evolution reaction.