An Ultrasonic Electrolysis Strategy for Monomethylamine Synthesis From Nitrate and CO₂

Electrocatalytic C─N coupling offers a feasible route for sustainable synthesis of monomethylamine (MMA), yet it still suffers from poor C/N reactant coactivation and low conversion efficiency. In this study, we propose an innovative ultrasonic electrolysis strategy for efficient MMA electrosynthesis from NO₃ ^- and CO₂. A bimetallic COF catalyst (CuBi-ppc) is rationally designed and employed as a model catalyst. Mechanistic investigations reveal that ultrasonic electrolysis induces the unique acoustic cavitation effect which enriches CO₂/NO₃ ^- reactants, promotes water dissociation for active H generation and stabilizes key C/N intermediates to facilitate C─N bond formation, consequently creating a favorable microenvironment to promote C─N coupling for selective MMA synthesis. Under the optimized ultrasonic electrolysis conditions, we achieve the high MMA yield rate of 144.89 mmol h^-1g^-1 and Faradaic efficiency of 91.86% along with an excellent stability. These results highlight the great potential of ultrasonic electrolysis strategy for powerful and sustainable organonitrogen electrosynthesis.