Bimetallic In–Sn Core–Shell Catalyst Enabling Highly Efficient Electrocatalytic CO2 Reduction to Formate

Bimetallic catalysts are ideal candidates for boosting electrochemical CO2 reduction reaction (CO2RR). However, these catalysts have largely relied on tedious synthesis technology and play electrolytic role with the help of a metal substrate or gas diffusion electrode. Herein, noble metal-free In–Sn nanoparticles (NPs) with a core–shell structure that contains a hybrid In–Sn core and native Sn-doped In2O3 shell have been successfully grown on the copper foam by the potential-driven volume diffusion strategy. These NPs which spontaneously result in the formation of the In–Sn bimetallic interface by adjusting the element composition significantly boost the yield of CO2 reduction into formate over a wide potential window (−0.77 to −1.17 V versus reversible hydrogen electrodes) compared with pure single-metal counterparts. The optimized In–Sn NPs deliver a great partial current density of 57.6 mA cm–2 and high faradaic efficiency of 97.0%, a remarkable performance in comparison to the state-of-the-art reported bimetallic catalyst. Such excellent performance is revealed via in situ Raman analyses and theoretical calculations, indicating that the unique structure of In–Sn NPs with the In–Sn bimetallic interface favorably regulates the reaction dynamics and facilitates the adsorption of the *OCHO intermediate.