Operando evidence of Cu+ stabilization via a single-atom modifier for CO2 electroreduction

Abstract

Oxide-derived Cu materials are most commonly used as electrocatalysts for the carbon dioxide reduction reaction (CO₂RR). Previous studies have proved that Cu⁺ and residual subsurface oxygen species can enhance the CO₂RR activity; however the stable presence of Cu⁺ remains a subject of debate. Here, we design a strategy of single-atom Sn anchored on Cu₂O nanosheets to stabilize the key Cu⁺ species for electroreduction of CO₂. Operando synchrotron X-ray absorption spectroscopy and statistics analysis distinguish the active Cu⁺ and reduced Cu⁺ species, and reveal that the constructed Sn–O–Cu sites with charge transfer can significantly enhance the resistance of copper oxides to reduction. Operando infrared spectroscopy suggests that the survival of Cu⁺ species on the catalyst surface promotes the adsorption of *CO during the CO₂RR, leading to the obvious improvement of CO₂-to-CO conversion. Our results demonstrate the role of a single-atom-modifier in both stabilizing Cu⁺ species and enhancing the CO₂RR selectivity of oxide-derived Cu catalysts.