Sn catalyst reconstruction and microenvironment modulation for efficient amino acid electrosynthesis via C–N coupling

Abstract

Abstract The electrosynthesis of amino acids represents a fascinating and promising frontier in green chemistry, offering a sustainable alternative to conventional industrial processes such as the energy-intensive Strecker synthesis through the adoption of efficient, electricity-driven methods. Herein, Sn is identified as an effective catalyst for glycine electrosynthesis using concentrated nitric acid and oxalic acid as feedstocks, and we investigate the reaction mechanism at industrial-level current rate (1 A cm -2 ). In-situ characterization reveals 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 reaction, we achieve a glycine Faradaic efficiency of 93%, and industrial-level partial current density of 0.9 A cm −2 in a flow cell.