Selective Glycine Electrosynthesis via C‐N Coupling Enabled by Synergistic Mott–Schottky Heterojunction and Oxygen Vacancies

Glycine, an indispensable amino acid essential for diverse biological processes, remains challenging to synthesize directly via electrosynthesis from simple carbon and nitrogen precursors. Herein, we report a highly efficient electrochemical route for glycine production through the reductive coupling of oxalic acid (H₂C₂O₄) with hydroxylamine (NH₂OH) or nitrate (NO₃ ⁻) over a Mott-Schottky Sn/SnO₂ heterojunction catalyst enriched with oxygen vacancies. When employing H₂C₂O₄ and NH₂OH as feedstocks, a remarkable Faradaic efficiency (FE) of 91.6% for glycine is achieved at -0.7 V versus RHE, alongside a high yield of 135 mmol gcat. ⁻¹ h⁻¹. To the best of our knowledge, this represents one of the best performances ever reported in this system. The catalyst also shows strong substrate versatility, enabling efficient glycine formation when NO₃ ⁻ (in situ reduced to NH₂OH) couples with glyoxylic acid or H₂C₂O₄. Mechanistic studies indicate that the Mott-Schottky heterojunction significantly promotes the co-adsorption of H₂C₂O₄ and NH₂OH, while oxygen vacancies facilitate the hydrogenation of oxime intermediates to glycine. This study highlights the profound synergistic interplay between Mott-Schottky heterojunctions and oxygen vacancy defects in precisely modulating active sites and accelerating reaction kinetics, thereby offering a sustainable strategy for the green electrosynthesis of amino acids.