Zn─F Diatomic Sites Promote Electrochemical C─N Coupling for the Synthesis of Amino Acids.

Abstract

While electrocatalytic C─N coupling offers a promising route for amino acid synthesis, its efficiency is limited by complex reaction pathways and competitive adsorption of reactants and intermediates on single-site catalysts. Herein, we report a catalyst with F and Zn diatomic sites on MnO2-x that enables the efficient synthesis of various amino acids from keto acids and nitrate through electrocatalytic C─N coupling in neutral electrolytes. For alanine synthesis, this catalyst exhibits a high Faradaic efficiency (FE) of 76.25% and a production rate of 543.02 µmol cm-2 h-1 across a broad potential window from -0.3 to -1.3 VRHE, while maintaining stable operation for over 300 h. In a membrane electrode assembly reactor, the catalyst sustains stable alanine production for 200 h with an average FE of 70.86%, enabling the practical isolation of 44.72 g of alanine. In situ spectroscopic and theoretical calculations demonstrate a tandem catalytic cascade, in which nitrate reduction proceeds to NH2OH on MnO2-x, NH2OH then spontaneously condenses with keto acids adsorbed on Zn sites to form C═N oxime intermediates, and these oximes migrate to F sites for hydrogenation to amino acids. This work offers insights into diatomic-site design for amino acid electrosynthesis and promotes the sustainable production of high-value organonitrogen compounds.