Bismuthene with stable Bi O bonds for efficient CO2 electroreduction to formate

Atomic configuration engineering is a promising strategy to realize the efficient and precise CO2 electroreduction towards the targeted products. Herein, an in-situ electrochemical transformation strategy was performed to construct the atomically thin bismuthene nanosheets with rich and stabilized BiO bonds (OBi-ene) from Bi2O2S precursor for CO2 electroreduction to formate. Electrochemical and thermodynamic characterizations confirm that rich BiO bonds could greatly enhance the CO2 adsorption on catalyst surface, which significantly accelerates the initial electron-transfer step of CO2 electroreduction for forming the key CO2·- intermediate. Consequently, the OBi-ene catalyst exhibits both high Faraday efficiency (>90%) and cathodic energy efficiency (>60%) to produce formate at wide current range from 50 to 400 mA cm−2 in flow cell. Impressively, a large current density of 200 mA cm−2 can be achieved only at 2.98 V in a full cell. This work provides a feasible strategy to design Bi-based electrocatalysts for efficient CO2 electroreduction.