Hierarchically ordered porous superstructure embedded with readily accessible atomic pair sites for enhanced CO2 electroreduction

Herein, a hierarchically ordered porous superstructure of N-doped carbon embedded with readily accessible Fe-Ni diatomic sites (FeNi DASs/HOPSNC) has been synthesized for highly efficient CO2 electroreduction. By integrating additional secondary mesopores into the ordered macroporous skeleton, this distinctive superstructure exhibits greatly enhanced accessibility and mass transfer. Benefiting from the unique structure merits including the synergistic effect in Fe-Ni atomic pair sites and the multi-level porosity, such diatomic site catalyst affords an outstanding electrocatalytic performance with excellent activity and selectivity for CO2-to-CO conversion and remarkable stability. Furthermore, systematic characterizations and density functional theory calculations unveiled that the electronic interaction within the diatomic pairs leads to the optimized electronic state and decreased reaction energy barrier for generating COOH* intermediate and weakening the binding strength of CO*, thereby improving the intrinsic catalytic activity and selectivity. This work may inspire further development of high-performance diatomic site catalysts for CO2 electroreduction and other electrosynthesis.