Mechanistic Insights into Methylamine Electrosynthesis from CO2 and NO on Co-Based Dual-Atom Catalysts

Methylamine (MMA) is a vital raw material in the chemical industry. Recent advances in electrochemical synthesis have enabled new routes for amide production via the coreduction of CO2 and nitrogen oxides. However, achieving selective C–N coupling with high Faradaic efficiency remains challenging due to the complexity of reaction intermediates and poorly understood mechanisms. In this study, we employed state-of-the-art constant-potential DFT calculations and microkinetic simulations to elucidate the mechanism of MMA electrosynthesis on heterogeneous single-atom/dual-atom catalysts (SACs/DACs) based on Co-phthalocyanine (Co-Pc) frameworks. We identified three critical factors governing C–N coupling selectivity: (i) the adsorption manner of CO2 and NO, (ii) the energy barrier of the initial Langmuir–Hinshelwood (LH) step, and (iii) the free energy change associated with over-reduction of *NH2OH and *HCHO intermediates. Guided by these criteria, we demonstrated the superior catalytic performance of Co-based DACs over that of their SAC counterpart. Furthermore, we highlighted the hydrogen affinity of the transition metal center as a critical parameter for rational DAC design and identified 2D Co–Ir-Pc as a promising electrocatalyst for MMA production, predicted to significantly outperform the experimentally validated Co-Pc monomers. This work not only provides mechanistic insights into C–N coupling on SACs/DACs but also establishes a general framework for the rational design of efficient MMA electrosynthesis catalysts.