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Sustainable oxime production via the electrosynthesis of hydroxylamine in a free state

Nature Synthesis volume 4, pages 1598–1609 (2025)Cite this article

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Abstract

Hydroxylamine (NH2OH) is an important feedstock for oxime production. Coreduction of NOx and aldehydes or ketones enables sustainable one-step oximation by utilizing in situ *NH2OH intermediates but suffers from side reactions and reduced current density due to the presence of multiple reactants in one reactor. Here we decouple oximation into two steps, the electrochemical synthesis of free NH2OH via nitrite (NO2−) electroreduction and the aldehyde or ketone oximation chemical step, circumventing the negative effects (such as site blocking, aldehyde or ketone electroreduction, or crossover) encountered in one-step oximation. By using a Ketjen-black-supported iron phthalocyanine as the catalyst, we achieve an exceptionally high partial current density of free NH2OH (jNH2OH) of 262.9 mA cm−2 (corresponding to productivity of 2.452 mmol cm−2 h−1) in neutral conditions at an industrially relevant current density of 500 mA cm−2. By coupling NH2OH electrosynthesis with subsequent oximation in two steps, nearly stoichiometric oximes are produced with high efficiency and broad applicability. This work paves the way toward a sustainable oxime industry.

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Fig. 1: Comparison of different oxime electrosynthesis routes.
Fig. 2: Free NH2OH production over a FePc-KB catalyst.
Fig. 3: Comparison between one-step and two-step oximation.
Fig. 4: Understanding selective production of free NH2OH over FePc-KB.
Fig. 5: MEA performance for oxime electrosynthesis at industrially relevant current densities.
Fig. 6: TEA and CO2 emission LCA.

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Data availability

The data supporting the finding of the study are available in the main text or Supplementary Information. Source data are provided with this paper, and at Zenodo via https://zenodo.org/records/16354033 (ref. 58).

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Acknowledgements

This work was supported by the National Key R&D Program of China (2023YFA1507400), the National Natural Science Foundation of China (grant numbers 22325805 and 22402107), the Beijing Natural Science Foundation (JQ22003), the Haihe Laboratory of Sustainable Chemical Transformations (24HHWCSS00007), and Tsinghua University Dushi Program and Center of High Performance Computing, Tsinghua University. J.L. was supported by the Postdoctoral Fellowship Program of CPSF (GZB20240475) and the Fundamental Research Funds for the Central Universities. The authors thank X. Gao, K. Kong, Q. Shi and K. Ji for useful discussions.

Author information

Author notes

  1. These authors contributed equally: Jing Li, Xiang Liu.

Authors and Affiliations

  1. College of Carbon Neutrality Future Technology, Sichuan University, Chengdu, China

    Jing Li

  2. Department of Chemistry, Tsinghua University, Beijing, China

    Jing Li, Xiang Liu, An-Zhen Li, Ye Wang, Xi Wang, Tiancong Zhou & Haohong Duan

  3. Jiangxi Provincial Key Laboratory of Synthetic Pharmaceutical Chemistry, Gannan Normal University, Ganzhou, China

    Si-Min Xu

  4. College of Chemistry, Chemical Engineering and Resource Utilization, Center for Innovative Research in Synthetic Chemistry and Resource Utilization, Northeast Forestry University, Harbin, China

    Ming Xu

  5. School of Environment, Tsinghua University, Beijing, China

    Yunlong Wang, Yizheng Lyu & Yue Peng

  6. State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, China

    Hua Zhou

  7. State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China

    Xuning Li

  8. Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China

    Lirong Zheng

  9. Haihe Laboratory of Sustainable Chemical Transformations, Tianjin, China

    Haohong Duan

  10. Engineering Research Center of Advanced Rare Earth Materials (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, China

    Haohong Duan

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Contributions

J.L. and X.L. designed and carried out the synthesis, characterizations and catalytic reactions, analysed the data and wrote the paper. S.-M.X. performed DFT. M.X. and L.Z. performed XAS and analysis. Yunlong Wang and Y.P. performed flue gas analysis. Y.L. and X.W. carried out the LCA. A.-Z.L. and Ye Wang helped with in situ Fourier-transform infrared spectroscopy. X.L. performed Mӧssbauer spectroscopy. T.Z. assisted with catalyst synthesis. H.Z. provided help with electrolyser assembly. H.D. supervised the project, conceived the idea, helped design the experiments, analysed the data and wrote the paper. All the authors commented on the paper and have approved the final version.

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Correspondence to Si-Min Xu or Haohong Duan.

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The authors declare no competing interests.

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Nature Synthesis thanks Feng Jiao, Hyungjun Kim, Tengfei Li and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Primary Handling Editor: Alexandra Groves, in collaboration with the Nature Synthesis team.

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Supplementary information

Supplementary Information

Supplementary Notes 1–19, Figs. 1–68, Tables 1–8 and References.

Source data

Source Data Fig. 2

Free NH2OH production over a FePc-KB catalyst.

Source Data Fig. 3

Comparison between one-step oximation and two-step oximation.

Source Data Fig. 4

Understanding of selective production of free NH2OH over FePc-KB.

Source Data Fig. 5

MEA performance for oxime electrosynthesis at industrially relevant current density.

Source Data Fig. 6

Technoeconomic analysis and CO2 emission life-cycle assessment.

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Li, J., Liu, X., Xu, SM. et al. Sustainable oxime production via the electrosynthesis of hydroxylamine in a free state. Nat. Synth 4, 1598–1609 (2025). https://doi.org/10.1038/s44160-025-00879-4

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