Understanding the role of axial O in CO2 electroreduction on NiN4 single-atom catalysts via simulations in realistic electrochemical environment

Electrochemical CO2 reduction reaction (CO2RR) is a very important approach to realize sustainable development. Single-atom catalysts show advantages in both homogeneous and heterogeneous catalysis, and considerable progress has been made in optimizing the performance of catalysts by controlling local coordination environment, especially through out-of-plane methods. In this work, we used an explicit solvent model combined with the "slow-growth" method and thermodynamic integration to investigate the influence of an axial oxygen atom on graphene-supported NiN4 moiety catalysts on CO2RR. The axial oxygen significantly promotes CO2 activation, computationally disclosed by simluations in realistic electrochemical environment. Our results provide a new perspective for CO2RR catalyzed by single-atom catalysts.