Electrochemical reduction of SnO2 to Sn from the Bottom: In-Situ formation of SnO2/Sn heterostructure for highly efficient electrochemical reduction of carbon dioxide to formate

Design and engineering of low-cost, high-performance catalysts is a critical step in electrochemical CO2 reduction (CO2R) to value-added chemicals and fuels. Herein, SnO2 nanoparticles were grown onto carbon cloth (SnO2/CF) by a facile hydrothermal procedure and exhibited excellent electrocatalytic activity towards CO2R due to reconstruction into SnO2/Sn Mott-Schottky heterojunctions during CO2R electrolysis, as manifested in X-ray diffraction, X-ray photoelectron spectroscopy, and operando Raman spectroscopy measurements. The heterostructured SnO2/Sn electrode delivered a high faradaic efficiency of 93 ± 1% and a partial current density of 28.7 mA cm−2 for formate production at − 1.0 V vs. reversible hydrogen electrode in an H-type cell (which remained stable for 9 h), and 174.86 mA cm−2 at − 1.18 V on a gas-diffusion electrode in a flow cell. Density functional theory calculations show that the SnO2/Sn heterostructures in situ formed under CO2R conditions helped decrease the energy barrier to form formate as compared to pristine SnO2 and Sn, and were responsible for the high activity and selectivity of formate production. Results from this study unravels the evolution dynamics of SnO2 catalysts under CO2R condition and provides a further understanding of the active component of SnO2 catalyst in CO2R.