Oxygen vacancy stabilized Bi2O2CO3 nanosheet for CO2 electroreduction at low overpotential enables energy efficient CO-production of formate

Bismuth-based electrocatalysts are promising candidates for electrochemical CO2 reduction to formate attributing to the accelerated formation of *OCHO intermediate, while the high-energy consumption remains a major challenge for practicability. Herein, we present the ultrathin Bi2O2CO3 nanosheets with abundant oxygen vacancy (Vo-BOC-NS) reconstructed from S, N-co-doped bismuth oxides that can act as durable electrocatalyst for CO2-to-formate conversion with faradic efficiency (FEformate) of >95%, partial current density of 286 mA cm(-2) with energy efficiency of 73.8% at -0.62 V (vs. RHE) and low overpotential of 200 mV in a flow electrolyzer. The theoretical calculations decipher that the oxygen vacancy can optimize *OCOH adsorption/desorption for the accelerated conversion kinetics. The pair-electrosynthesis tactic of formate co-production can enable a superior FEformate of >90% at wide cell voltage of 2-3.3 V and total yield rate of 3742 mu mol cm(-2) h(-1) at 3.3 V, suggesting great potential for future industrialization.