Computational Insights on Electrocatalytic Synthesis of Methylamine from Nitrate and Carbon Dioxide

Carbon dioxide (CO2) and nitrate (NO3 (-)) co-reduction to valuable chemicals, e.g., methylamine(MMA) production, by electricity generated from renewable energy sources,has been considered as a promising route for electrochemical synthesis.However, the mechanism of C-N coupling in the process is keyand remains unclear. Herein, we studied the (quasi) activity trend over a set of metal phthalocyanine (MPc) via densityfunctional theory (DFT) calculations and reaction phase diagram analysis.Surprisingly, we found that the lowest barrier for C-N couplingis via desorbed HCHO and NH2OH rather than either beingadsorbed on the catalyst. Then, we performed kinetic barrier calculationsand microkinetic modeling over CoPc-NH2, which waspreviously observed with the capability of producing MMA, to understandthe Faradaic efficiency trends of MMA and other products at differentpotentials. Our kinetic model provides important insights for improvingthe MMA activity and selectivity and is useful for catalyst designfor C-N coupling in general.