Synergistic Catalysis in Fe─In Diatomic Sites Anchored on Nitrogen-Doped Carbon for Enhanced CO₂ Electroreduction

Diatomic catalysts are promising for the electrochemical CO₂ reduction reaction (CO₂RR) due to their maximum atom utilization and the presence of multiple active sites. However, the atomic-scale design of diatomic catalysts and the elucidation of synergistic catalytic mechanisms between multiple active centers remain challenging. In this study, heteronuclear Fe─In diatomic sites anchored on nitrogen-doped carbon (FeIn DA/NC) are constructed. The FeIn DA/NC electrocatalyst achieves a CO Faradaic efficiency exceeding 90% across a wide range of applied potentials from -0.4 to -0.7 V, with a peak efficiency of 99.1% at -0.5 V versus the reversible hydrogen electrode. In situ, attenuated total reflection surface-enhanced infrared absorption spectroscopy and density functional theory calculations reveal that the synergistic interaction between Fe and In diatomic sites induce an asymmetric charge distribution, which promote the adsorption of CO₂ at the Fe site and lowered the energy barrier for the formation of ^*COOH. Moreover, the unique Fe─In diatomic site structure increase the adsorption energy of ^*OH through a bridging interaction, which decrease the energy barrier for water dissociation and further promoted CO₂RR activity.