Unlocking the In Situ Reconstruction of Bi/Bi ₂ O ₂ CO ₃ Electrocatalyst Toward Efficiently Converting CO ₂ into Formate

Abstract Electrochemical reducing CO ₂ into formic acid has been demonstrated to be an economically viable pathway to relieve the greenhouse effect and obtain value‐added chemical feedstocks. Herein, Bi/Bi ₂ O ₂ CO ₃ is developed via the combination of sulfur‐assisted disassembly and an in situ reconstruction process. Profiting from the enlarged surface area and the generation of the high active heterointerface between metallic Bi and Bi ₂ O ₂ CO ₃ , the as‐obtained Bi/Bi ₂ O ₂ CO ₃ exhibits high performance toward converting CO ₂ molecules into formate (HCOO ⁻ ), attaining the HCOO ⁻ Faradaic efficiency (FE _HCOO‐ ) over 97% in the current density range from 200 to 1000 mA cm ⁻² in both alkaline (1 m KOH) and near neutral (0.5 m KHCO ₃ ) electrolytes, along with excellent stability. In situ spectroscopic data unraveled the reconstruction process from Bi ₂ S ₃ /Bi ₂ O ₂ CO ₃ to Bi/Bi ₂ O ₂ CO ₃ and corroborated that the conversion of CO ₂ into formate is through the ^* OCHO intermediate, deepening the insights into the understanding of the Bi‐based electrocatalyst reconstruction and CO ₂ RR mechanism.