Formic acid (or formate) is suggested to be one of the most economically viable products from electrochemical carbon dioxide reduction. However, its commercial viability hinges on the development of highly active and selective electrocatalysts. Here we report that structural defects have a profound positive impact on the electrocatalytic performance of bismuth. Bismuth oxide double-walled nanotubes with fragmented surface are prepared as a template, and are cathodically converted to defective bismuth nanotubes. This converted electrocatalyst enables carbon dioxide reduction to formate with excellent activity, selectivity and stability. Most significantly, its current density reaches ~288 mA cm⁻² at −0.61 V versus reversible hydrogen electrode within a flow cell reactor under ambient conditions. Using density functional theory calculations, the excellent activity and selectivity are rationalized as the outcome of abundant defective bismuth sites that stabilize the *OCHO intermediate. Furthermore, this electrocatalyst is coupled with silicon photocathodes and achieves high-performance photoelectrochemical carbon dioxide reduction.

甲酸（或甲酸盐）被认为是电化学还原二氧化碳最经济可行的产品之一。然而，其商业可行性取决于高活性和选择性电催化剂的开发。在这里，我们报道结构缺陷对铋的电催化性能产生了深远的积极影响。将具有碎片表面的氧化铋双壁纳米管作为模板，并将其阴极转化为有缺陷的铋纳米管。这种转化的电催化剂能够以优异的活性，选择性和稳定性将二氧化碳还原成甲酸酯。最重要的是，其电流密度达到〜288 mA cm ^-2在-0.61 V的条件下，与流通池反应器中的可逆氢电极在环境条件下相比。使用密度泛函理论计算，将出色的活性和选择性合理化为稳定* OCHO中间体的大量缺陷铋位的结果。此外，该电催化剂与硅光电阴极偶联，可实现高性能的光电化学二氧化碳还原。