Efficient Glycine Electrosynthesis via CO-Recyclable Hydrogen Donation on Pb/PbBi Heterointerfaces.

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 CO-mediated strategy for glycine electrosynthesis using oxalic acid and N/nitrate as feedstocks. By using Pb/PbBi-CO 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 N as the nitrogen source, the glycine production rate could maintain at 94.4 µmol h cm with N-selectivity as high as 93.2%. Mechanistic investigations combining experiments and theoretical calculations reveal that CO undergoes facile protonation on the Pb/PbBi heterointerfaces to form OCOH intermediate, which donates hydrogen for the reduction of oxalic acid and nitrate into glyoxylic acid and NHOH, respectively, while CO 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.