A co-carbonization strategy for confining ultralow-loaded Fe/Mn dual sites in hierarchically porous N-doped carbon for synergistic CO2 electroreduction

Abstract

Recent studies have witnessed the great prospect of bi-atom catalysts (BACs) in realizing effective electrocatalytic CO₂ reduction. However, the precisely controllable syntheses of BACs with outstanding properties remain a significant challenge. Herein, the first bi-atom Fe/Mn–N–C catalyst for CO₂ reduction was successfully developed by the co-carbonization of Fe/Mn co-doped ZIF-8 (Fe/Mn@ZIF-8) and carbon black. This strategy enhances the conductivity and induces the confinement effect of carbon supports, which contributes to anchoring trace Fe/Mn dual sites on hierarchically porous N-doped carbon. The bimetallic Fe/Mn–N–C catalyst exhibits an excellent CO faradaic efficiency of 95.7% at a low overpotential of 370 mV vs. RHE. DFT results reveal that the coexistence of trace Mn sites can strengthen the catalytic capabilities of Fe active sites in bimetallic Fe/Mn–N–C. The synergistic effect of ultralow-loaded Fe/Mn dual sites is favorable for the adsorption and activation of CO₂ as well as *CO desorption from Fe active sites, boosting the entire CO₂-to-CO transformation. This work provides valuable insight into the rational design of BACs for efficient CO₂ electroreduction.