Derived CuSn Alloys from Heterointerfaces in Bimetallic Oxides Promote the CO2 Electroreduction to Formate

Abstract Electroreduction of CO2 into valuable chemicals provides a promising strategy for mitigating excessive CO2 emissions and storing intermittent renewable energy. Herein, SnO2/CuOnanoparticle composites (NCs) with rich heterointerfaces were designed for selectively converting CO2 into liquidus formate. Distinct from only monometallic phase evolved in physically‐mixed samples, Cu and Sn atoms at the heterointerfaces were in‐situ reduced into alloys under working conditions. With residual SnOx/CuOx stabilizing the CO2.− intermediate, CuSn alloys can obviously suppress the undesired hydrogen evolution reaction and then enhance the catalytic selectivity. In a H‐type cell, as‐obtained SnO2/CuO NCs exhibit Faraday efficiency (FE) of 89.3 % and current density of 18.34 mA cm−2 for formate, which is stable for 30 h at −1.0 V vs. RHE. Impressively, the formate current density of 310 mA cm−2 is achieved in a flow cell. Moreover, constructing efficient samples by the heterointerfaces engineering would provide an inspiration for designing novel electrocatalysts.