Tailoring local structures of atomically dispersed copper sites for highly selective CO2 electroreduction

Abstract

AbstractAtomically‐dispersed copper sites coordinated with nitrogen‐doped carbon (Cu–N–C) can provide novel possibilities to enable highly selective and active electrochemical CO2 reduction reactions. However, the construction of optimal local electronic structures for nitrogen‐coordinated Cu sites (Cu–N4) on carbon remains challenging. Here, we synthesized the Cu–N–C catalysts with atomically‐dispersed edge‐hosted Cu–N4 sites (Cu–N4C8) located in a micropore between two graphitic sheets via a facile method to control the concentration of metal precursor. Edge‐hosted Cu–N4C8 catalysts outperformed the previously reported M–N–C catalysts for CO2‐to‐CO conversion, achieving a maximum CO Faradaic efficiency (FECO) of 96%, a CO current density of –8.97 mA cm–2 at –0.8 V versus reversible hydrogen electrode (RHE), and over FECO of 90% from –0.6 to –1.0 V versus RHE. Computational studies revealed that the micropore of the graphitic layer in edge‐hosted Cu–N4C8 sites causes the d‐orbital energy level of the Cu atom to shift upward, which in return decreases the occupancy of antibonding states in the *COOH binding. This research suggests new insights into tailoring the locally coordinated structure of the electrocatalyst at the atomic scale to achieve highly selective electrocatalytic reactions.