Electrocatalytic reduction of CO₂ to formate is an attractive avenue for CO₂ utilization. Unfortunately, existing catalysts suffer from low faradic efficiency of formate production at high current density. Here, we report a general strategy for preparing the Bi₂O₂CO₃ nanosheet (BOC-NS) with abundant oxygen vacancies through in situ electrically driven conversion of the BiPO₄ precursor. The converted BOC-NS displays high faradic efficiency of formate (FE_HCOO⁻) (∼100%) over a wide potential region in an H-type cell and achieves a formate partial current density of −930 mA cm⁻² with a FE_HCOO⁻ of 93% at −1.55 V_RHE in a flow cell. Experimental results and density functional theory (DFT) calculations confirm that the BOC-NS surface with abundant oxygen vacancies benefit formate production, which stems from fast reaction kinetics toward the formation of ∗OCHO intermediate on defective Bi₂O₂CO₃ nanosheets. This work provides helpful guidance for designing efficient electrocatalysts via in situ electrochemical transformation.

电催化将CO ₂还原为甲酸是利用CO ₂的诱人途径。不幸的是，现有的催化剂在高电流密度下的甲酸盐生产法拉第效率低。在这里，我们报告通过BiPO ₄前体的原位电驱动转换制备具有大量氧空位的Bi ₂ O ₂ CO ₃纳米片（BOC-NS）的一般策略。转换后的BOC-NS在H型电池的宽电位区域中显示出高的法拉第效率（FE _HCOO ^-）（〜100％），并通过FE达到了-930 mA cm ^-2的甲酸分电流密度_HCOO ^- 93％在-1.55 V _RHE在流动池中。实验结果和密度泛函理论（DFT）计算证实，具有大量氧空位的BOC-NS表面有利于甲酸生成，这是由于快速的反应动力学导致在有缺陷的Bi ₂ O ₂ CO ₃纳米片上形成* OCHO中间体。这项工作为通过原位电化学转化设计有效的电催化剂提供了有益的指导。