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

SnO 2 has been recognized as excellent catalyst towards formate production from electrochemical CO 2 reduction (CO 2 R). However, it is a great challenge to prepare SnO 2 that is stable under the working condition of CO 2 R and the active center of the SnO 2 -based catalyst towards CO 2 R has been illusive. In this work, Sn-In alloy nanoparticles display an InSn 4 intermetallic core and an amorphous In-doped tin oxide shell and a CO 2 -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 CO 2 R 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 CO 2 -to-formate, which might account for the high performance of the catalysts towards CO 2 R.