Synergistic catalysis on Sn-Bi heterostructures for highly selective electrosynthesis of glycine

Electrocatalytic co-reduction of abundant carbon and nitrogen feedstocks opens a promising route for the sustainable production of amino acids. However, mismatched reduction rates between carbon and nitrogen sources and the sluggish reaction kinetics remain great challenges preventing its practical application. Herein, we report synergistic catalysis over Sn-Bi heterostructures for highly selective electrosynthesis of glycine from oxalic acid and nitrate. The optimal Sn-Bi/C catalyst exhibits a high glycine Faradaic efficiency of 79.7%, a partial current density of 163.7 mA cm^-2, and a carbon selectivity of 80.2%, enabling gram-scale production of glycine in a long-term electrolysis. Mechanistically, Sn sites accelerate nitrate reduction to hydroxylamine, Bi sites drive oxalic acid reduction to glyoxylic acid, and the Sn-Bi interfaces favor the reduction of glyoxylic acid oxime to glycine. The interfacial electron transfer between Sn and Bi modifies the p-band center, thereby regulating the adsorption behavior of key intermediates during the reduction of glyoxylic acid oxime. By precisely coordinating the site-specific reduction of nitrate and oxalic acid on Sn and Bi sites, respectively, the formation rates of the key C- and N-containing intermediates are kinetically matched. This synergistic catalytic strategy significantly enhances C-N coupling efficiency and accelerates glycine formation kinetics, thereby establishing a new design paradigm for electrocatalysts toward controllable C-N coupling.