Operando Converting BiOCl into Bi(2)O(2)(CO(3))(x)Cl(y) for Efficient Electrocatalytic Reduction of Carbon Dioxide to Formate

Bismuth-based materials (e.g., metallic, oxides and subcarbonate) are emerged as promising electrocatalysts for converting CO(2) to formate. However, Bi(o)-based electrocatalysts possess high overpotentials, while bismuth oxides and subcarbonate encounter stability issues. This work is designated to exemplify that the operando synthesis can be an effective means to enhance the stability of electrocatalysts under operando CO(2)RR conditions. A synthetic approach is developed to electrochemically convert BiOCl into Cl-containing subcarbonate (Bi(2)O(2)(CO(3))(x)Cl(y)) under operando CO(2)RR conditions. The systematic operando spectroscopic studies depict that BiOCl is converted to Bi(2)O(2)(CO(3))(x)Cl(y) via a cathodic potential-promoted anion-exchange process. The operando synthesized Bi(2)O(2)(CO(3))(x)Cl(y) can tolerate − 1.0 V versus RHE, while for the wet-chemistry synthesized pure Bi(2)O(2)CO(3), the formation of metallic Bi(o) occurs at − 0.6 V versus RHE. At − 0.8 V versus RHE, Bi(2)O(2)(CO(3))(x)Cl(y) can readily attain a FE(HCOO)- of 97.9%, much higher than that of the pure Bi(2)O(2)CO(3) (81.3%). DFT calculations indicate that differing from the pure Bi(2)O(2)CO(3)-catalyzed CO(2)RR, where formate is formed via a (*)OCHO intermediate step that requires a high energy input energy of 2.69 eV to proceed, the formation of HCOO(−) over Bi(2)O(2)(CO(3))(x)Cl(y) has proceeded via a (*)COOH intermediate step that only requires low energy input of 2.56 eV. [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40820-022-00862-0.