In situ catalyst reconstruction and microenvironment modula-tion for efficient amino acid electrosynthesis via C–N coupling

Electrosynthesis of amino acids is a novel and promising green synthetic strategy. However, the lack of efficient catalysts limits catalytic performance, in terms of reaction rate and Faradaic efficiency. Here, Sn is identified as an effective catalyst for glycine electrosynthesis using concentrated nitric acid and oxalic acid as feedstocks, and we investigated the reaction mechanism at industrial-level cur-rent rate (1 A cm-2). In-situ characterization (XRD, Raman spectroscopy, XAS, etc.) revealed that the Sn undergoes dynamic valence cycle and reconstructs into amorphous-Sn under acidic conditions. At high current, the change in local pH promotes the anionic states of oxalic acid and C-intermediates, which enhances the adsorption of key intermediates such as glyoxalic acid and acid oxime. This switches the mechanism from a chain reaction to an interfacial hydrogenation, thereby increasing the rate of glycine formation. By increasing the dominance of interfacial reaction versus the chain reac-tion, we achieved a glycine FE of 93%, and industrial-level patrial current density of 0.9 A cm−2 in a flow cell.