Solar energy powered electrochemical reduction of CO on InO nanosheets with high energy conversion efficiency at a large current density.

Electrochemical CO reduction (ECOR) to value-added chemicals offers a promising approach to both mitigate CO emission and facilitate renewable energy conversion. We demonstrate a solar energy powered ECOR system operating at a relatively large current density (57 mA cm) using InO nanosheets (NSs) as the cathode and a commercial perovskite solar cell as the electricity generator, which achieves the high solar to formate energy conversion efficiency of 6.6 %. The significantly enhanced operative current density with a fair solar energy conversion efficiency on InO NSs can be ascribed to their high activity and selectivity for formate production, as well as the fast kinetics for ECOR. The Faradic efficiencies (FEs) of formate InO NSs are all above 93 %, with the partial current density of formate ranging from 2.3 to 342 mA cm in a gas diffusion flow cell, which is among the widest for formate production on In-based catalysts. In-situ Raman spectroscopy and density functional theory simulations reveal that the exceptional performances of formate production on InO NSs originates from the presence of abundant low coordinated edge sites, which effectively promote the selective adsorption of *OCHO while inhibiting *H adsorption.