Sn-doping stabilizes residual oxygen species to promote intermediate desorption for enhanced CO2 to CO conversion

The presence of oxygen species on the surface of Cu oxides can improve carbon dioxide (CO2) adsorption and lower the binding energy of oxygenic intermediates, thereby increasing the first-step reduction products of CO2 electro-reduction. Herein, the residual oxygen on Cu2O was stabilized using Sn2+ during the reduction process, and the retention of residual oxygen was confirmed using an in-situ Raman spectrum (Cu-Oads). Simultaneously, in-situ Raman and density functional theory calculations revealed that the adsorption energy of carbon monoxide intermediate (*CO) on SnO/Cu2O catalyst was considerably lower than that on bare Cu2O catalyst due to the presence of residual oxygen. This resulted in an increased Faradic efficiency of 97.5% for CO production at a relevant potential of −0.8 V (vs. reversible hydrogen electrode). The oxygen stabilizing strategy for Cu oxide catalysts is inspiring in designing high-performance catalysts for CO2 electroreduction.