Directing the Electrochemical C─N Coupling Toward Efficient Amide Synthesis via Ammonia Activation-Mediated Pathway.

Abstract

Electrochemically oxidative C─N coupling using alcohol and ammonia as feedstocks offers a sustainable alternative for the chemosynthesis of amide organonitrogens. The achievements of high activity and selectivity yet remains challenging via the conventional alcohol oxidation pathway. Here, we present an alternative ammonia-activation mediated pathway to favor the electrochemical C─N coupling necessary. Spectroscopic and theoretical investigations untangle that this manipulated process begins with the oxidation of ammonia to endow active *NH2 species, which then efficiently couple with alcohol species to form C─N bonds. This alternative C─N coupling pathway exhibits accelerated kinetics and, more importantly, bypasses the formation of aldehyde intermediate, thereby preventing unfavorable overoxidation. As a result, this pathway achieves a high Faradaic efficiency of 50.1% and a carbon selectivity of 87.6% for efficient formamide electrosynthesis over a NiCuRu-based (oxy)hydroxide catalyst, with a productivity of 557.2 µmol cm-2 h-1. Such electrosynthetic approach further exhibit the universality of waste biomass/plastics-driven carbon feedstocks, achieving considerable Faradaic efficiencies of 32%-60%. Techno-economic analysis confirms the potential profitability of using renewable electricity input, highlighting the significant advantages of green chemical manufacturing for sustainable development.