Promoting Glycine Electrosynthesis from Nitrate and Oxalic Acid over Co–Cu Dual-Site Metal–Organic Frameworks

Abstract

Electrochemical coreduction of nitrate (NO3–) and oxalic acid to glycine (ENOG) provides a sustainable alternative to conventional glycine production but remains limited by sluggish reactant activation, inefficient C–N coupling, and competing reaction pathways. Herein, a dual-site metal–organic framework, CoTAPc-BPDA-Cu, is developed as an efficient and robust cathode catalyst for ENOG. Operando spectroscopic measurements and theoretical calculations reveal the cooperative effect of Cu–Co dual sites in promoting OA-to-*C2H2O3 conversion, *NO3 reduction to *NH2OH, *C2H2O3-*NH2OH coupling to *C2H3NO3, and subsequent *C2H3NO3 hydrogenation for selective glycine formation. Moreover, by integrating cathodic ENOG over the CoTAPc-BPDA-Cu catalyst with an anodic glycerol oxidation over the PbO2 catalyst in a two-electrode electrolyzer, we achieve a glycine Faradaic efficiency of 78.3% and a glycine yield rate of 629.3 mmol h−1 g−1, while enabling the gram-scale production of high-purity glycine.