Axial Coordination Regulating Single Atoms for Enhanced CO2 Electroreduction

Abstract

With the merits of high atomic utilization and well-defined configuration, metal−nitrogen−carbon (M−N−C) single-atomic catalysts (SACs), show great capability in selective reduction of CO2 into CO and formate. However, the metal center with the planar configuration of M−N4 has a highly symmetric structure, which is not conductive to charge transfer, thus limiting the intrinsic activity of SACs. Introduction of axially coordinated atoms with M−N4 center can break the symmetry and optimize the intermediate adsorption for accelerating CO2 reduction. Here, we briefly discuss the CO2RR pathway on single atoms and introduce the emerging synthetic methods for SACs with axial ligands. Then we review the axial coordination effect on CO2RR behavior. This review will be helpful for understanding the working mechanism of axially coordinated single atoms for enhancing CO2RR performance and thereby designing ideal coordination ligand in the axial direction.