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.