In-situ electrochemical transformation of F-modified metallic bismuth for highly-efficient CO2 electroreduction and Zn-CO2 battery

A high-efficient electrocatalyst of F-modified Bi catalyst (FD-Bi) is firstly developed by electrochemical conversion from a bismuth oxyfluoride (BiOF) precursor, which delivers excellent catalytic performance for the electrocatalytic CO2 reduction to formate and Zn-CO2 batteries. [Display omitted] •F-anion modified Bi catalyst (FD-Bi) is firstly prepared by in-situ electrochemical transformation of BiOF precursor.•The FD-Bi catalyst achieves high FEformate of over 90 % in wide potential range of −0.5 ∼ -1.2 V.•The FD-Bi catalyst has optimized electronic structure and the favorable adsorption energies of intermediates.•Zn-CO2 battery equipped with FD-Bi delivers a high power density of 2.68 mW·cm−2 and superior operation stability. Electrocatalytic CO2 reduction (ECO2R) to produce formate is one of the essential routes for CO2 upgrading. Herein, the bismuth oxyfluoride (BiOF) material is firstly rationally designed as a precursor to derive the F-modified Bi catalyst (FD-Bi) for ECO2R. The FD-Bi catalyst achieves more than 90 % Faradaic efficiency of formate (FEformate) over a wide potential range of −0.5 ∼ -1.2 V vs. RHE. By coupling in-situ Raman and infrared spectroscopy, the transformation of BiOF to FD-Bi and the formation of key *OCHO intermediates have been revealed. Density functional theory (DFT) calculations further confirm the optimized electronic structure and the favorable adsorption energies of intermediates on F-modified Bi catalyst. In a coupled system for the co-production of formate, a high FEformate of 159.1 % can be realized at a small cell voltage of 1.9 V. In addition, Zn-CO2 battery equipped with FD-Bi delivers a high power density of 2.68 mW·cm−2 and superior stability.