Electrochemical reduction of CO₂ (ECO₂RR) to formate is one of effective approaches to achieve carbon recycling processes. Despite Bi nanosheets (NSs) have been proven to be highly selective in ECO₂RR to formate, the understanding of the true active sites is needed to further dig out the potential of catalytic activity of Bi NSs. In this work, we developed a rational synthesis approach to manipulate the basal-/edge-plane ratio of Bi NSs via topotactic reduction of (004)-oriented Bi₅O₇I NSs and (102)-oriented BiOI NSs to reveal the contribution of basal and edge planes on the performance of ECO₂RR. In comparison with edge-oriented Bi NSs, basal-oriented Bi NSs show higher catalytic activity. DFT calculations have proven that the competition of the kinetically favored HER would be inhibited on basal planes of Bi NSs, indicating the increasement of the proportion of basal planes on Bi NSs or Bi based 2D catalysts improves ECO₂RR conversion efficiency.

将 CO ₂ (ECO ₂ RR)电化学还原为甲酸盐是实现碳回收过程的有效方法之一。尽管已证明 Bi 纳米片 (NSs) 在 ECO ₂ RR 中具有高度的甲酸选择性，但仍需要了解真正的活性位点以进一步挖掘 Bi NSs 催化活性的潜力。在这项工作中，我们开发了一种合理的合成方法，通过（004）取向的 Bi ₅ O ₇ I NSs 和（102）取向的 BiOI NSs 的拓扑还原来操纵 Bi NSs 的基面/边缘平面比，以揭示其贡献ECO ₂性能的基面和边缘平面RR。与边缘取向的 Bi NSs 相比，基底取向的 Bi NSs 显示出更高的催化活性。DFT 计算已经证明动力学有利的 HER 的竞争将在 Bi NSs 的基面上受到抑制，表明 Bi NSs 或 Bi 基二维催化剂上基面比例的增加提高了 ECO ₂ RR 转换效率。