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

Authors: Xu, Guangkuo; Dong, Chengyuan; Cai, Xiangcheng; Kuang, Junhua; Xue, Tianwei; Guo, Yuyu; Wu, Yanyin; Li, Ruiqing; Shao, Zeyu; Qiao, Tongxin; Hao, Wenli; Xu, Longzhao; Yang, Shuliang; Li, Jun; Peng, Li

Abstract: ABSTRACT 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 (H 2 C 2 O 4 ) with hydroxylamine (NH 2 OH) or nitrate (NO 3 − ) over a Mott–Schottky Sn/SnO 2 heterojunction catalyst enriched with oxygen vacancies. When employing H 2 C 2 O 4 and NH 2 OH 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 g cat. −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 NO 3 − (in situ reduced to NH 2 OH) couples with glyoxylic acid or H 2 C 2 O 4 . Mechanistic studies indicate that the Mott–Schottky heterojunction significantly promotes the co‐adsorption of H 2 C 2 O 4 and NH 2 OH, 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.

Full-Link: https://onlinelibrary.wiley.com/doi/10.1002/anie.5717711