Monoclinic Scheelite Bismuth Vanadate Derived Bismuthene Nanosheets with Rapid Kinetics for Electrochemically Reducing Carbon Dioxide to Formate

Electrochemical reduction of CO₂ to high-value chemical feedstocks, such as formate, is one of the most promising ways to alleviate the greenhouse effect. Unfortunately, the exploration of electrocatalysts with high activity and selectivity over a wide potential window (especially low potential for high current density) still remains a grand challenge. In this study, the fabrication of bismuthene nanosheets using an in-situ electrochemical transformation strategy of monoclinic scheelite BiVO₄ flakes is demonstrated. Catalyzing the CO₂ electroreduction in 1 m KHCO₃ aqueous solution, the bismuthene nanosheets exhibit a dramatically high formate Faradaic efficiency (FE) of ≈97.4% and a very large current density of −105.4 mA cm⁻² at −1.0 V versus reversible hydrogen electrode. Significantly, over a record wide potential window of 750 mV from the initial −0.65 V to the applied minimum −1.4 V, the formate FEs of the bismuthene nanosheets are always higher than 90%, outperforming state-of-the-art electrocatalysts. Both experimental and theoretical investigations reveal that, in comparison with ^•COOH and H^• intermediates, the bismuthene nanosheets preferentially promote fast reaction kinetics towards HCOO^•, which eventually accelerates the production of formate.