Synthesis of Bi/Fe–N–C catalysts for efficient electrochemical CO2-to-CO reduction

Abstract

Single atom Fe sites, doped in CN materials, exhibit outstanding electrochemical activity for CO₂-to-CO conversion. The pyrolysis of ZIF8 is a controllable method for fabricating isolated single atom metal sites. In this study, we propose a new strategy to increase the ratio of Fe in ZIF8 precursors by synergistically replacing Zn²⁺ with Bi³⁺ and Fe³⁺. After precursor pyrolysis, the obtained Bi/Fe–N–C catalysts, consisting of Bi sites and pyrrole-type Fe–N_x sites, serve as efficient electrocatalysts for the CO₂RR. The results show that the optimized catalyst loaded with 94.8 mg per kg_Cat Fe exhibits a high FE_CO of >90.1% over a wide potential range of −0.4 to −0.7 V_RHE (98.2% at −0.5 V_RHE). Insights into the electrochemical reaction mechanism show that this successful design of Bi/Fe–N–C catalysts can provide a stable catalytic site to form *COOH, thus achieving energy-efficient electrochemical CO₂ reduction to CO.