Cu-modified Bi nanorods stabilize HCOO* intermediates for efficient CO2-to-formate electrocatalytic conversion

Abstract

The electrocatalytic carbon dioxide reduction reaction (CO₂RR) is a promising approach for simultaneous CO₂ mitigation and production of value-added chemicals. Bismuth has been demonstrated as a fascinating electrocatalyst for the selective conversion of CO₂ to formate. However, the stability of single-metal bismuth catalysts and selectivity of formate are still unsatisfactory. Herein, rod-like Cu-doped Bi catalysts were synthesized by controlled oxidation of CuBi/CNF precursors. These catalysts exhibited excellent performance in the CO₂RR, achieving a formate Faraday efficiency (FE_Formate) of 92.39% at −1.4 V (vs. RHE) and maintaining stability for 32 h. In situ spectroscopy analysis confirmed that HCOO* intermediates dominated the formate production reaction of the CO₂RR. The metal doping strategy enables the Bi catalysts to increase the FE_Formate by about 13% at a potential of −1.4 V (vs. RHE). The introduction of Cu results in a lattice compressive strain, which can change the monomolecular structure of Bi, and the synergy between the bimetals improves the binding of adsorbed species, enhancing the activation of CO₂. The in situ FT-IR calculation demonstrated that HCOO* rather than a *COOH pathway benefits the stability of bismuth catalysts and formate selectivity for the CO₂RR. This work offers insights into improving the catalytic performance of bismuth catalysts for the CO₂RR.