A tin-based tandem electrocatalyst for CO 2 reduction to ethanol with 80% selectivity

Most catalysts that generate appreciable amounts of multicarbon products from electrochemical CO 2 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 CO 2 to ethanol. Our data suggest the catalyst is largely composed of SnS 2 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.