Crystal facet regulation of tin for electrochemical carbon dioxide reduction to formate

The electrochemical CO 2 reduction reaction (CO 2 RR) to formate represents a promising route for high-value CO 2 utilization. Which helps address environmental issues and enables energy storage. Tin (Sn)-based catalysts are widely used in CO 2 RR for formate production, yet the impact of crystal facets remains unreported. Here, we revealed the effect of Sn facets on CO 2 RR to formate. Sn electrodes with different facet preferences were obtained by controlling the electroreduction rate. The Sn-3 electrode with preferential (101) facet exposure achieved 87.8 % Faradaic efficiency (FE) for formate with a large partial current density ( j ), which is higher than that with abundant (200) facet (Sn-1) and a mixture of (200) and (101) facets (Sn-2). In membrane electrode assembly (MEA), the FE HCOOH of 88.5 % was obtained at the large current density of 500 mA cm −2 on Sn-3. Theoretical calculations and comprehensive experimental investigations revealed that the Sn(101) facet is conducive to the adsorption of *OCHO, thereby reducing the reaction energy barrier and enhancing formate generation during CO 2 RR. This work provides an understanding of Sn crystal facets for efficient CO 2 RR to formate.