In-Sn alloy core-shell nanoparticles: In-doped SnOx shell enables high stability and activity towards selective formate production from electrochemical reduction of CO2

Abstract SnO2 has been recognized as excellent catalyst towards formate production from electrochemical CO2 reduction (CO2R). However, it is a great challenge to prepare SnO2 that is stable under the working condition of CO2R and the active center of the SnO2-based catalyst towards CO2R has been illusive. In this work, Sn-In alloy nanoparticles display an InSn4 intermetallic core and an amorphous In-doped tin oxide shell and a CO2-to-formate faradaic efficiency of 94% and a current density of 236 mA cm−2 was achieved at −0.98 V. Operando X-ray absorption and Raman spectroscopy reveal that the In-doped tin oxide shell remains stable under CO2R condition. Density functional theory calculations indicate that the In-doped tin oxide results in the formation of oxygen vacancy, stabilized tin oxide shell and exergonic pathway for CO2-to-formate, which might account for the high performance of the catalysts towards CO2R.