A tin-based tandem electrocatalyst for CO2 reduction to ethanol with 80% selectivity

Most catalysts that generate appreciable amounts of multicarbon products from electrochemical CO2 reduction are based on Cu. However, the limited understanding of C-C coupling processes over Cu-based catalysts hinders design of more efficient catalysts. Here we report a Cu-free, Sn-based electrocatalyst that exhibits high catalytic performance for reduction of CO2 to ethanol. Our data suggest the catalyst is largely composed of SnS2 nanosheets and single Sn atoms coordinated with three oxygen atoms on three-dimensional carbon. The catalyst achieves a maximum selectivity of approximately 82.5% at 0.9 V-RHE (reversible hydrogen electrode, RHE) and more than 70% over a wide electrode potential window (-0.6 to -1.1 V-RHE); it also maintains 97% of its initial activity (with a geometric current density of 17.8 mA cm(-2) at 0.9 V-RHE) after 100 hours of reaction. First principles modelling suggests that dual active centres comprising Sn and O atoms can adsorb *CHO and *CO(OH) intermediates, respectively, therefore promoting C-C bond formation through a formyl-bicarbonate coupling pathway.