Self-supported mesoscopic tin oxide nanofilms for electrocatalytic reduction of carbon dioxide to formate

Here we report a self-supported SnO₂ nanofilm prepared by a robust electrochemical process as an electrocatalyst for the CO₂ reduction reaction. The SnO₂ film had a large surface area originating from its nano-architecture and manifested high selectivity toward formate (over 60%), which resulted in CO₂-to-formate current density up to 33.66 mA cm^-2 that is among the state-of-the-art. We unveiled that the high performance of the SnO₂ nanofilm is attributable to the presence of a metastable oxide under reductive conditions in addition to the abovementioned advantages.