Trifunctional Cobalt Single-Atom Catalyst with Axial Chloride Coordination to Achieve Efficient Methylamine Electrosynthesis: A Constant-Potential DFT Study

Abstract

Electrochemical methylamine (MMA) synthesis from nitrate (NO3-) and carbon dioxide (CO2) offers a promising approach for sustainable MMA production, yet its progress remains largely limited due to the sluggish C-N coupling process and the lack of effective catalysts. For this purpose, a system with efficient trifunctionality on NO3- reduction, CO2 reduction and the crucial C-N coupling sites is essential on single atom catalysts (SACs) for efficient MMA production. Through systematically investigate by performing constant-potential density functional theory calculations, axially chlorine coordinated Co single-atom catalysts anchoring on graphene (CoN4(Cl)@G with the outstanding trifunctionality is finally identified from a series of TMN4(Cl)@G and TMN4@G (TM = Fe, Co, Ni) systems. Furthermore, A distinct MMA mechanism, namely the migratable CO species directly couples with the *NH2 intermediate and forms the key precursor *NH2CO (*NH2-CO → *NH2CO) is evidenced both thermodynamic and kinetic feasible (with low energy barrier of 0.48 eV). Consequently, this work presents a practical strategy for MMA synthesis starting from graphene-supported single-atom sites, and also advances mechanistic insight into C-N bond formation.