Cu-Bi Bimetallic Catalysts Derived from Metal-Organic Framework Arrays on Copper Foam for Efficient Glycine...

Glycine as one of the most abundant amino acids in human proteins, with extensive applications in both life and industry, is conventionally synthesized through complex procedures or toxic feedstocks. In this study, we present a facile and benign electrochemical pathway for synthesis of glycine through reductive coupling of glyoxylic acid and nitrate over a copper-bismuth bimetal catalyst derived from a metal-organic framework (MOF) array on copper foam (Cu/Bi-C@CF). Remarkably, Cu/Bi-C@CF achieves a fantastic selectivity of 89 %, corresponding a high Faraday efficiency of 65.9 %. From control experiments, the introduction of Bi caused the binding energy of Cu shift to a lower state, which leads to a high selectivity towards the formation of key intermediate hydroxylamine rather than ammonia product, facilitating the formation of oxime and providing additional sites for subsequent hydrogenation reaction on the way to glycine. Moreover, the derivation of MOF arrays ensures the effective dispersion of Bi and enhances the stability of Cu/Bi-C@CF. This innovative approach not only presents sustainable pathways for the production of value-added organonitrogen compounds utilizing readily available carbon and nitrogen sources, but also provides novel insights into the design of multistage structural catalysts for sequential reactions.