Efficient Glycine Electrosynthesis via CO

Electrochemical synthesis has emerged as a sustainable platform in constructing C─N bonds for amino acid production. Glycine, a particularly valuable target compound, continues to experience escalating global demand, yet achieving simultaneous high efficiency and operational stability remains a persistent challenge. Herein, we demonstrate a CO2-mediated strategy for glycine electrosynthesis using oxalic acid and N2/nitrate as feedstocks. By using Pb/Pb7Bi3-CO2 catalytic system, a very high glycine Faradaic efficiency (FE) of 91.8% with durable stability over 120 h could be achieved. Moreover, when using nonthermal plasma-activated N2 as the nitrogen source, the glycine production rate could maintain at 94.4 µmol h-1 cm-2 with N-selectivity as high as 93.2%. Mechanistic investigations combining experiments and theoretical calculations reveal that CO2 undergoes facile protonation on the Pb/Pb7Bi3 heterointerfaces to form *OCOH intermediate, which donates hydrogen for the reduction of oxalic acid and nitrate into glyoxylic acid and NH2OH, respectively, while CO2 is simultaneously regenerated. Notably, hydrogenation via the *OCOH intermediate significantly lowers the energy barriers compared to direct protonation, thereby promoting the subsequent spontaneous C─N bond formation and enabling highly efficient electrosynthesis of glycine.