Halide-guided carbon-affinity active sites in BimOnBrp-derived Bi2O2CO3 for efficient electrocatalytic CO2 reduction to formate

Bismuth oxyhalides (BimOnXp, where X represents Cl, Br, and I) present a promising family of template catalysts for in situ Bi2O2CO3 synthesis to achieve the highly efficient CO2 electrochemical reduction reaction (CO2RR) toward formate. However, the specific mechanism behind BimOnXps' structural reconstruction and their subsequent effects on CO2RR performance remain unresolved inquiries. In this study, a comprehensive investigation into how halogens (Cl, Br, and I) influence BimOnXp CO2RR performance was conducted. It is suggested that Br is capable of introducing a bismuth-rich phase (Bi(2)4O(3)1Br10) in BiOBr, which promotes the formation of external Bi-O structural characteristics and leads to exceptional CO2RR performance, with a faradaic efficiency (FEHCOO-) of 90.67% and a formate partial current density (JHCOO-) of 52.31 mA cm(-2), surpassing those of BiOCl and BiOI. Kinetic simulations suggest that the alternative Bi-O structure will promote the combination of the Bi-O structure and carbon-based intermediates, leading to the improved kinetics of the rate-determining step, and ultimately resulting in better CO2RR performance.