Abstract

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.