Restraining Interfacial Cu²⁺ by using Amorphous SnO₂ as Sacrificial Protection Boosts CO₂ Electroreduction

Abstract The electrochemical carbon dioxide reduction reaction (CO₂RR) to formate is of great interest in the field of electrochemical energy. Cu‐based material is an appealing electrocatalyst for the CO₂RR. However, retaining Cu²⁺ under the high cathodic potential of CO₂RR remains a great challenge, leading to low electrocatalytic selectivity, activity, and stability. Herein, inspired by corrosion science, a sacrificial protection strategy to stabilize interfacial crystalline CuO through embedding of active amorphous SnO₂ (c‐CuO/a‐SnO₂) is reported, which greatly boosts the electrocatalytic sensitivity, activity, and stability for CO₂RR to formate. The as‐made hybrid catalyst can achieve superior high selectivity for CO₂RR to formate with a remarkable Faradaic efficiency (FE) of 96.7%, and a superhigh current density of over 1 A cm⁻² that far outperforms industrial benchmarks (FE > 90%, current density > 300 mA cm⁻²). In situ X‐ray absorption spectroscopy (XAS) and X‐ray diffractionexperimental and theoretical calculation results reveal that the broadened s‐orbital in interfacial a‐SnO₂ offers the lower orbital for extra electrons than Cu²⁺, which can effectively retain nearby Cu²⁺, and the high active interface significantly lowers the energy barrier of the limited step (^*CO₂ → ^*HCOO) and enhances the selectivity and activity for CO₂RR to formate.