Abstract
Direct electrochemical C–N coupling from abundant carbon and nitrogen sources offers a sustainable route for glycine synthesis, yet achieving high efficiency is challenging. This study developed an IL@Bi catalyst by anchoring ionic liquid (IL) 1-ethyl-2,3-dimethylimidazolium nitrate (EmmimNO3) on Bi. For the co-reduction of oxalic acid and NO3−, the IL@Bi catalyst achieved a Faradaic efficiency toward glycine (FEglycine) of 81.1% with a current density of 286.2 mA cm−2, outperforming pristine Bi and reported state-of-the-art catalysts. Large-scale glycine synthesis was demonstrated, with a glycine production rate of 3.6 mol h−1 gcat−1. Using plasma-activated N2 as the nitrogen source, glycine selectivity reached 89.0%. Mechanism studies demonstrated that oxalic acid and NO3− were first reduced to glyoxylate oxime (GAO), which could be reduced to glycine after accepting electrons. On the IL@Bi catalyst, electron transfer followed a relayed mechanism, where electrons were initially transferred from Bi to Emmim+, forming the Emmim· radical, which then donated electrons to GAO, resulting in a faster conversion pathway than direct electron transfer from Bi to GAO and contributing to the outstanding catalytic performance.
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Acknowledgements
The work was supported by the National Natural Science Foundation of China (22273108, 22033009, 22293015, 22121002), the Beijing Natural Science Foundation (2222043), the CAS Project for Young Scientists in Basic Research (YSBR-050), the Youth Innovation Promotion Association CAS (Y2022017), the ICCAS Carbon Neutral Chemistry programme (CCNC-202403) and the National Key Research and Development Program of China (2023YFA1507400).
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H.W. conducted experiments and relevant characterizations. Y.C. helped with electrochemical measurements and ATR-SEIRAS measurements. Y.W., W.Z. and H.Q. helped with ATR-SEIRAS measurements. R.D. and Y.P. contributed to EPR testing and analysis. M.Z. and J.Y. contributed to the plasma-driven conversion of air to NOx experiment. S.L. and X.K. contributed to discussion of DFT and data analysis of the calculations. L.J., Y.X., Q.Z., X.S., Q.Q. and J.Z. helped with the data analysis. X.K. and B.H. designed and supervised the entire project. H.W., X.K. and B.H. wrote the paper. All authors contributed to the discussion of results and the preparation of the paper.
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Wang, H., Cheng, Y., Wang, Y. et al. Imidazolium radical-mediated electron transfer enhances electrochemical C–N coupling for glycine synthesis. Nat. Synth 5, 74–83 (2026). https://doi.org/10.1038/s44160-025-00892-7
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DOI: https://doi.org/10.1038/s44160-025-00892-7
