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Direct synthesis of hydrazine by efficient electrochemical ruthenium-catalysed ammonia oxidation

Nature Catalysis volume 6, pages 949–958 (2023)Cite this article

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Abstract

A century after hydrazine was discovered, its synthesis remains a challenge due to its high energy requirement and favourable subsequent conversion. As an alternative to the traditional industrial processes, the direct electrochemical oxidation of ammonia is an ideal reaction for hydrazine synthesis. However, suitable methods still need to be developed. Here we show that ruthenium complexes bearing 2-[5-(pyridin-2-yl)-1H-pyrrol-2-yl]pyridine ligands display high catalytic activity for the direct electrochemical oxidation of ammonia to generate hydrazine in acetonitrile. Our developed CSU-2 complex reached a turnover number for hydrazine formation of 5,735 within 24 h at an applied potential of 1.0 V versus Cp2Fe+/0. The results reveal a bimolecular N‒N coupling mechanism involving RuII–aminyl or RuIII–iminyl intermediates.

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Fig. 1: Synthesis and structure of complexes explored in this work.
Fig. 2: Cyclic voltammetry and CPC experiments of CSU complexes.
Fig. 3: The possible mechanism of ammonia oxidation catalysed by the CSU-2 complex.

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Data availability

Crystallographic data for the structures reported in this article have been deposited at the Cambridge Crystallographic Data Centre, under deposition numbers CCDC 2158154 (CSU-1) and 2158155 (CSU-2). Copies of the data can be obtained free of charge via https://www.ccdc.cam.ac.uk/structures/. Source data are provided with this paper. All other data supporting the findings of this study are available within the article and its supplementary information or from the corresponding author upon request.

References

  1. Schirmann, J. P. & Bourdauducq, P. in Ullmann’s Encyclopedia of Industrial Chemistry Vol. 18, 79–96 (Wiley, 2012).

  2. Rothgery, E. F. in Kirk-Othmer Encyclopedia of Chemical Technology Vol. 13, 562–607 (Wiley, 2004).

  3. Elishav, O. et al. Progress and prospective of nitrogen-based alternative fuels. Chem. Rev. 120, 5352–5436 (2020).

    Article  CAS  PubMed  Google Scholar 

  4. Serov, A. et al. Anode catalyst for direct hydrazine fuel cells: from laboratory test to an electric vehicle. Angew. Chem. Int. Ed. 53, 10336–10339 (2014).

    Article  CAS  Google Scholar 

  5. Raschig, F. Vorlesungsversuche aus der Chemie der anorganischen Stickstoffverbindungen. Ber. Dtsch. Chem. Ges. 40, 4587 (1907).

    Article  Google Scholar 

  6. Wang, F., Gerken, J. B., Bates, D. M., Kim, Y. J. & Stahl, S. S. Electrochemical strategy for hydrazine synthesis: development and overpotential analysis of methods for oxidative N–N coupling of an ammonia surrogate. J. Am. Chem. Soc. 142, 12349–12356 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  7. Cheddie, D. Hydrogen Energy—Challenges And Perspectives (ed. Minić, D.) Ch. 13 (IntechOpen, 2012).

  8. Afif, A. et al. Ammonia-fed fuel cells: a comprehensive review. Renew. Sust. Energ. Rev. 60, 822–835 (2016).

    Article  CAS  Google Scholar 

  9. Adli, N. M., Zhang, H., Mukherjee, S. & Wu, G. Review—ammonia oxidation electrocatalysis for hydrogen generation and fuel cells. J. Electrochem. Soc. 165, J3130–J3147 (2018).

    Article  CAS  Google Scholar 

  10. Nakajima, K., Toda, H., Sakata, K. & Nishibayashi, Y. Ruthenium-catalysed oxidative conversion of ammonia into dinitrogen. Nat. Chem. 11, 702–709 (2019).

    Article  CAS  PubMed  Google Scholar 

  11. Bhattacharya, P. et al. Catalytic ammonia oxidation to dinitrogen by hydrogen atom abstraction. Angew. Chem. Int. Ed. 58, 11618–11624 (2019).

    Article  CAS  Google Scholar 

  12. Habibzadeha, F., Millera, S. L., Hamanna, T. W. & Smith, M. R. III Homogeneous electrocatalytic oxidation of ammonia to N2 under mild conditions. Proc. Nat. Acad. Sci. USA 116, 2849–2853 (2019).

    Article  Google Scholar 

  13. Dunn, P. L., Johnson, S. I., Kaminsky, W. & Bullock, R. M. Diversion of catalytic C–N bond formation to catalytic oxidation of NH3 through modification of the hydrogen atom absorption. J. Am. Chem. Soc. 142, 3361–3365 (2020).

    Article  CAS  PubMed  Google Scholar 

  14. Holub, J. et al. Synthesis, structure and ammonia oxidation catalytic activity of Ru-NH3 complexes containing multidentate polypyridyl ligands. Inorg. Chem. 60, 13929–13940 (2021).

    Article  CAS  PubMed  Google Scholar 

  15. Trenerry, M. J., Wallen, C. M., Brwon, T. R., Park, S. V. & Berry, J. F. Spontaneous N2 formation by a diruthenium complex enables electrocatalytic and aerobic oxidation of ammonia. Nat. Chem. 13, 1221–1227 (2021).

    Article  CAS  PubMed  Google Scholar 

  16. Zott, M. D., Garrido-Barros, P. & Peters, J. C. Electrocatalytic ammonia oxidation mediated by a polypyridyl iron catalyst. ACS Catal. 9, 10101–10108 (2019).

    Article  CAS  Google Scholar 

  17. Zott, M. D. & Peters, J. C. Enhanced ammonia oxidation catalysis by a low-spin iron complex featuring cis-coordination sites. J. Am. Chem. Soc. 143, 7612–7616 (2021).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  18. Li, Y. et al. A parent iron amido complex in catalysis in catalysis of ammonia oxidation. J. Am. Chem. Soc. 144, 4365–4375 (2022).

    Article  CAS  PubMed  Google Scholar 

  19. Toda, H. et al. Manganese-catalyzed ammonia oxidation into dinitrogen under chemical or electrochemical conditions. ChemPlusChem 86, 1511–1516 (2021).

    Article  CAS  PubMed  Google Scholar 

  20. Liu, H.-Y. et al. Electrocatalytic, homogeneous ammonia oxidation in water to nitrate and nitrite with a copper complex. J. Am. Chem. Soc. 144, 8449–8453 (2022).

    Article  CAS  PubMed  Google Scholar 

  21. Najafian, A. & Cundari, T. R. Computational mechanistic study of electro-oxidation of ammonia to N2 by homogenous ruthenium and iron complexes. J. Phys. Chem. A. 123, 7973–7982 (2019).

    Article  CAS  PubMed  Google Scholar 

  22. Dunn, P. L., Cook, B. J., Jobnson, S. I., Appel, A. M. & Bullock, R. M. Oxidation of ammonia with molecular complexes. J. Am. Chem. Soc. 142, 17845–17858 (2020).

    Article  CAS  PubMed  Google Scholar 

  23. Hayashi, H. Hydrazine synthesis by a catalytic oxidation process. Catal. Rev. Sci. Eng. 32, 229–277 (1990).

    Article  CAS  Google Scholar 

  24. Hayashi, H., Kainoh, A., Katayama, M., Kawasaki, K. & Okazaki, T. Hydrazine production from ammonia via azine. Ind. Eng. Chem. Prod. Res. Dev. 15, 299–303 (1976).

    CAS  Google Scholar 

  25. Gardner, E. J. et al. Uncovering redox non-innocent hydrogen-bonding in Cu(I)-diazene complexes. J. Am. Chem. Soc. 143, 15960–15974 (2021).

    Article  CAS  PubMed  Google Scholar 

  26. McSkimming, A. et al. An easy one-pot synthesis of diverse 2,5-di(2-pyridyl)pyrroles: a versatile entry point to metal complexes of functionalized, meridial and tridentate 2,5-di(2-pyridyl)pyrrolato ligands. Chem. Eur. J. 20, 11445–11456 (2014).

    Article  CAS  PubMed  Google Scholar 

  27. Trenerry, M. J., Wallen, C. M., Brown, T. R., Park, S. V. & Berry, J. F. Spontaneous N2 formation by a diruthenium complex enables electrocatalytic and aerobic oxidation of ammonia. Nat. Chem. 13, 1221–1227 (2021).

    Article  CAS  PubMed  Google Scholar 

  28. Watt, G. W. & Chrisp, J. D. Spectrophotometric method for determination of hydrazine. Anal. Chem. 24, 2006–2008 (1952).

    Article  CAS  Google Scholar 

  29. Gu, N. X., Oyala, F. H. & Peters, J. C. Hydrazine formation via coupling of a nickel(III)–NH2 radical. Angew. Chem. Int. Ed. 60, 4009–4013 (2021).

    Article  CAS  Google Scholar 

  30. Kundu, S., Dutta, D., Maity, S., Weyhermüller, T. & Ghosh, P. Proton-coupled oxidation of a diarylamine: amido and aminyl radical complexes of ruthenium(II). Inorg. Chem. 57, 11978–11960 (2018).

    Article  Google Scholar 

  31. Olivos Suarez, A. I., Lyaskovskyy, V., Reek, J. N. H., Vlugt, J. I. & Bruin, B. Complexes with nitrogen-centered radical ligands: classification, spectroscopic features, reactivity, and catalytic applications. Angew. Chem. Int. Ed. 52, 12510–12529 (2013).

    Article  Google Scholar 

  32. Collman, J. P., Hutchison, J. E., Ennis, M. S., Lopez, M. A. & Guilard, R. Reduced nitrogen hydride complexes of a cofacial metallodiporphyrin and their oxidative interconversion. An analysis of ammonia oxidation and prospects for a dinitrogen electroreduction catalyst based on cofacial metallodiporphyrins. J. Am. Chem. Soc. 114, 8074–8080 (1992).

    Article  CAS  Google Scholar 

  33. Sheldrick, G. M. SADABS. Program for empirical absorption correction of area detector data (Univ. Göttingen, 1996).

  34. SHELXL Manual (Bruker AXS, 1997).

  35. Chen, G. et al. Efficient electrochemical water oxidation mediated by pyridylpyrrole-carboxylate ruthenium complexes. Inorg. Chem. 60, 15627–15634 (2021).

    Article  CAS  PubMed  Google Scholar 

  36. Chen, G. et al. A Ru2II,III diphosphonato complex with a metal–metal bond for water oxidation. Dalton Trans. 50, 2018–2022 (2021).

    Article  CAS  PubMed  Google Scholar 

  37. Yang, J. et al. From Ru-bda to Ru-bds: a step forward to highly efficient molecular water oxidation electrocatalysts under acidic and neutral conditions. Nat. Commun. 12, 373 (2021).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  38. Shen, J., Wang, M., Zhang, P., Jiang, J. & Sun, L. Electrocatalytic water oxidation by copper(ii) complexes containing a tetra- or pentadentate amine-pyridine ligand. Chem. Commun. 53, 4374–4377 (2017).

    Article  CAS  Google Scholar 

  39. Chen, Q. et al. CoO nanoparticle decorated N-doped carbon nanotubes: a high-efficiency catalyst for nitrate reduction to ammonia. Chem. Commun. 58, 5091–5904 (2022).

    Article  Google Scholar 

  40. Zhu, D., Zhang, L., Ruther, R. E. & Hamers, R. J. Photo-illuminated diamond as a solid-state source of solvated electrons in water for nitrogen reduction. Nat. Mater. 12, 836–841 (2013).

    Article  CAS  PubMed  Google Scholar 

  41. Frisch, M. J. et al. Gaussian 16, Revision C.01 (Gaussian Inc., 2016).

  42. Adamo, C. & Barone, V. Toward reliable density functional methods without adjustable parameters: The PBE0. model. J. Chem. Phys. 110, 6158–6170 (1999).

    Article  CAS  Google Scholar 

  43. Grimme, S., Ehrlich, S. & Goerigk, L. Effect of the damping function in dispersion corrected density functional theory. J. Comput. Chem. 32, 1456–1465 (2011).

    Article  CAS  PubMed  Google Scholar 

  44. Weigend, F. & Ahlrichs, R. Balanced basis sets of split valence, triple zeta valence and quadruple zeta valence quality for H to Rn: Design and assessment of accuracy. Phys. Chem. Chem. Phys. 7, 3297–3305 (2005).

    Article  CAS  PubMed  Google Scholar 

  45. Weigend, F. Accurate Coulomb-fitting basis sets for H to Rn. Phys. Chem. Chem. Phys. 8, 1057–1065 (2006).

    Article  CAS  PubMed  Google Scholar 

  46. Marenich, A. V., Cramer, C. J. & Truhlar, D. G. Universal solvation model based on solute electron density and on a continuum model of the solvent defined by the bulk dielectric constant and atomic surface tensions. J. Phys. Chem. B 113, 6378–6396 (2009).

    Article  CAS  PubMed  Google Scholar 

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Acknowledgements

We thank G.-L. Liang from Southeast University, Z.-M. Yang from Nankai University and Q.-G. Wang from Tongji University for their encouragement, motivation and very fruitful discussions. We also thank Y.-W. Lin from the University of South China, L. Yu from the High Magnetic Field Laboratory of the Chinese Academy of Sciences for the EPR measurement and discussion and Z.-C. Zhang from Huaiyin Normal University for refinement of single crystal structures. X.-Y.Y. acknowledges the National Natural Science Foundation of China (21571190), the Foundation of Central South University Research Programme of Advanced Interdisciplinary (2023QYJC019) and the Natural Science Foundation of Hunan Province of China (2022JJ30689). G.C. thanks the Postgraduate Scientific Research Innovation Project of Hunan Province (CX20210170).

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Authors and Affiliations

  1. College of Chemistry and Chemical Engineering, Central South University, Changsha, People’s Republic of China

    Guo Chen, Piao He, Chao Liu, Xiu-Fang Mo, Jing-Jing Wei, Ze-Wen Chen, Tao Cheng, Li-Zhi Fu & Xiao-Yi Yi

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Contributions

X.-Y.Y. as the corresponding author contributed to project design and paper revision. G.C. mainly contributed to synthesis and electrocatalysis studies of the CSU complexes and writing the paper. P.H. mainly contributed to the DFT calculations. C.L. mainly contributed to X-ray diffraction analysis of the solid-state structures. X.-F.M., J.-J.W., Z.-W.C., T.C. and L.-Z.F. assisted with synthesis and characterization of complexes, CPC experiments and gas chromatography experiments and so on.

Corresponding author

Correspondence to Xiao-Yi Yi.

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Competing interests

Y.-X.Y. and G.C. have filed patents based on the work described here (China patent application no. 202111584527.X, international application no. PCT/CN2022/139184, US patent application no. 18272369, European patent application no. 22909854.6, Korean patent application no. 10-2023-7024287, Japanese patent application no. 2023-524432).

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Nature Catalysis thanks Jeffrey W. Bacon, Victor Batista, Ignacio Funes-Ardoiz, Sungho Park and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–82, Tables 1–4 and Note 1.

Supplementary Video 1

H2, N2H4 and N2 production in CPC experiments. Electrolytic conditions: 0.01 mM CSU-2 in NH3-saturated MeCN solutions at a constant potential of 0.76 V versus Cp2Fe+/0 at room temperature.

Supplementary Data 1

The atomic coordinates of the optimized models of CSU-1, CSU-2 and intermediates.

Supplementary Data 2

cif file of CSU-1.

Supplementary Data 3

cif file of CSU-2.

Source data

Source Data Fig. 2

Source data of Fig. 2

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Chen, G., He, P., Liu, C. et al. Direct synthesis of hydrazine by efficient electrochemical ruthenium-catalysed ammonia oxidation. Nat Catal 6, 949–958 (2023). https://doi.org/10.1038/s41929-023-01025-z

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