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Selective electrocatalytic synthesis of urea using entangled iron porphyrins in covalent organic frameworks

Nature Synthesis volume 4, pages 720–729 (2025)Cite this article

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Abstract

Electrocatalytic urea production from nitrate (NO3−) and carbon dioxide (CO2) provides a promising alternative to the traditional energy-intensive industrial process. However, promoting electrocatalytic carbon–nitrogen coupling and suppressing side reactions remains challenging. Here we report an efficient urea synthesis via electrochemical coupling of NO3− and CO2 using entangled iron porphyrins in three-dimensional covalent organic frameworks. The porous iron catalyst concentrates and cooperatively activates reactants, achieving a high Faradaic efficiency of 90.0%, a nitrogen selectivity of 92.4% and nearly 100% carbon selectivity. The catalyst achieves a urea yield rate of \(135.6\,{\mathrm{mmol}}\,{\mathrm{g}}_{\mathrm{cat}}^{-1}\,{\mathrm{h}}^{-1}\), while maintaining activity for >100 h. Experiments and theoretical calculations suggest the plentiful Fe–N4 sites within porphyrins efficiently facilitate the conversions of CO2 to *CO and NO3− to *NH2, and the spatial localization of twin iron sites overcomes the unordered transfer of intermediates, enabling vectored carbon–nitrogen coupling.

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Fig. 1: Design and synthesis of entangled framework catalysts with subnanoscale twin metal sites.
Fig. 2: Characterization of entangled framework catalysts with subnanoscale twin metal sites.
Fig. 3: Performance evaluation of catalysts for the electrosynthesis of urea.
Fig. 4: Unravelling the mechanism of electrocatalytic urea production involving twin iron sites.

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Data availability

All data are available in the main text or the Supplementary Information. Supplementary crystallographic data for PCOF-34-Fe, PCOF-90-Fe, PCOF-34 and PCOF-90 can be obtained free of charge via the Cambridge Crystallographic Data Centre at www.ccdc.cam.ac.uk/data_request/cif (CCDC 2345501, 2345502, 2345503 and 2345504, respectively).

References

  1. Zhang, X. et al. Managing nitrogen for sustainable development. Nature 528, 51–59 (2015).

    Article  CAS  PubMed  Google Scholar 

  2. Erisman, J. W., Sutton, M. A., Galloway, J., Klimont, Z. & Winiwarter, W. How a century of ammonia synthesis changed the world. Nat. Geosci. 1, 636–639 (2008).

    Article  CAS  Google Scholar 

  3. Qiao, J., Liu, Y., Hong, F. & Zhang, J. A review of catalysts for the electroreduction of carbon dioxide to produce low-carbon fuels. Chem. Soc. Rev. 43, 631–675 (2014).

    Article  CAS  PubMed  Google Scholar 

  4. Barzagli, F., Mani, F. & Peruzzini, M. From greenhouse gas to feedstock: formation of ammonium carbamate from CO2 and NH3 in organic solvents and its catalytic conversion into urea under mild conditions. Green Chem. 13, 1267–1274 (2011).

    Article  CAS  Google Scholar 

  5. Comer, B. M. et al. Prospects and challenges for solar fertilizers. Joule 3, 1578–1605 (2019).

    Article  CAS  Google Scholar 

  6. Li, J., Zhang, Y., Kuruvinashetti, K. & Kornienko, N. Construction of C–N bonds from small-molecule precursors through heterogeneous electrocatalysis. Nat. Rev. Chem. 6, 303–319 (2022).

    Article  CAS  PubMed  Google Scholar 

  7. Chen, C. et al. Coupling N2 and CO2 in H2O to synthesize urea under ambient conditions. Nat. Chem. 12, 717–724 (2020).

    Article  CAS  PubMed  Google Scholar 

  8. Regnier, P., Resplandy, L., Najjar, R. G. & Ciais, P. The land-to-ocean loops of the global carbon cycle. Nature 603, 401–410 (2022).

    Article  CAS  PubMed  Google Scholar 

  9. Schulte-Uebbing, L. F., Beusen, A. H. W., Bouwman, A. F. & de Vries, W. From planetary to regional boundaries for agricultural nitrogen pollution. Nature 610, 507–512 (2022).

    Article  CAS  PubMed  Google Scholar 

  10. Lv, C. et al. Selective electrocatalytic synthesis of urea with nitrate and carbon dioxide. Nat. Sustain. 4, 868–876 (2021).

    Article  Google Scholar 

  11. Wei, X. et al. Oxygen vacancy-mediated selective C–N coupling toward electrocatalytic urea synthesis. J. Am. Chem. Soc. 144, 11530–11535 (2022).

    Article  CAS  PubMed  Google Scholar 

  12. Lv, C. et al. A defect engineered electrocatalyst that promotes high-efficiency urea synthesis under ambient conditions. ACS Nano 16, 8213–8222 (2022).

    Article  CAS  PubMed  Google Scholar 

  13. Geng, J. et al. Ambient electrosynthesis of urea with nitrate and carbon dioxide over iron-based dual-sites. Angew. Chem. Int. Ed. 62, e202210958 (2023).

    Article  CAS  Google Scholar 

  14. Meng, N. et al. Oxide-derived core–shell Cu@Zn nanowires for urea electrosynthesis from carbon dioxide and nitrate in water. ACS Nano 16, 9095–9104 (2022).

    Article  CAS  PubMed  Google Scholar 

  15. Leverett, J. et al. Tuning the coordination structure of Cu–N–C single atom catalysts for simultaneous electrochemical reduction of CO2 and NO3- to urea. Adv. Energy Mater. 12, 2201500 (2022).

    Article  CAS  Google Scholar 

  16. Zhang, X. et al. Identifying and tailoring C–N coupling site for efficient urea synthesis over diatomic Fe–Ni catalyst. Nat. Commun. 13, 5337 (2022).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  17. Tao, Z., Rooney, C. L., Liang, Y. & Wang, H. Accessing organonitrogen compounds via C–N coupling in electrocatalytic CO2 reduction. J. Am. Chem. Soc. 143, 19630–19642 (2021).

    Article  CAS  PubMed  Google Scholar 

  18. Jiang, M. et al. Review on electrocatalytic coreduction of carbon dioxide and nitrogenous species for urea synthesis. ACS Nano 17, 3209–3224 (2023).

    Article  CAS  PubMed  Google Scholar 

  19. Ji, Y. et al. Selective CO-to-acetate electroreduction via intermediate adsorption tuning on ordered Cu–Pd sites. Nat. Catal. 5, 251–258 (2022).

    Article  CAS  Google Scholar 

  20. Li, X. et al. Selective visible-light-driven photocatalytic CO2 reduction to CH4 mediated by atomically thin CuIn5S8 layers. Nat. Energy 4, 690–699 (2019).

    Article  CAS  Google Scholar 

  21. Côté, A. P. et al. Porous, crystalline, covalent organic frameworks. Science 310, 1166–1170 (2005).

    Article  PubMed  Google Scholar 

  22. Liu, R. et al. Covalent organic frameworks: an ideal platform for designing ordered materials and advanced applications. Chem. Soc. Rev. 50, 120–242 (2021).

    Article  CAS  PubMed  Google Scholar 

  23. Wang, X. et al. Homochiral 2D porous covalent organic frameworks for heterogeneous asymmetric catalysis. J. Am. Chem. Soc. 138, 12332–12335 (2016).

    Article  CAS  PubMed  Google Scholar 

  24. Xu, X., Cai, P., Chen, H., Zhou, H.-C. & Huang, N. Three-dimensional covalent organic frameworks with she topology. J. Am. Chem. Soc. 144, 18511–18517 (2022).

    Article  CAS  PubMed  Google Scholar 

  25. Meng, Y. et al. 2D and 3D porphyrinic covalent organic frameworks: the influence of dimensionality on functionality. Angew. Chem. Int. Ed. 59, 3624–3629 (2020).

    Article  CAS  Google Scholar 

  26. Li, H. et al. Three-dimensional covalent organic frameworks with dual linkages for bifunctional cascade catalysis. J. Am. Chem. Soc. 138, 14783–14788 (2016).

    Article  CAS  PubMed  Google Scholar 

  27. Lin, S. et al. Covalent organic frameworks comprising cobalt porphyrins for catalytic CO2 reduction in water. Science 349, 1208–1213 (2015).

    Article  CAS  PubMed  Google Scholar 

  28. Lv, F. et al. Near-unity electrochemical conversion of nitrate to ammonia on crystalline nickel porphyrin-based covalent organic frameworks. Energy Environ. Sci. 16, 201–209 (2023).

    Article  CAS  Google Scholar 

  29. Shan, Z. et al. 3D covalent organic frameworks with interpenetrated pcb topology based on 8-connected cubic nodes. J. Am. Chem. Soc. 144, 5728–5733 (2022).

    Article  CAS  PubMed  Google Scholar 

  30. Gong, C. et al. Synthesis and visualization of entangled 3D covalent organic frameworks with high-valency stereoscopic molecular nodes for gas separation. Angew. Chem. Int. Ed. 61, e202204899 (2022).

    Article  CAS  Google Scholar 

  31. Zhu, Y. et al. Unravelling surface and interfacial structures of a metal–organic framework by transmission electron microscopy. Nat. Mater. 16, 532–536 (2017).

    Article  CAS  PubMed  Google Scholar 

  32. Zhang, D. et al. Atomic-resolution transmission electron microscopy of electron beam-sensitive crystalline materials. Science 359, 675–679 (2018).

    Article  CAS  PubMed  Google Scholar 

  33. Li, Y. et al. Atomic structure of sensitive battery materials and interfaces revealed by cryo-electron microscopy. Science 358, 506–510 (2017).

    Article  CAS  PubMed  Google Scholar 

  34. Dong, C., Kou, T., Gao, H., Peng, Z. & Zhang, Z. Eutectic-derived mesoporous Ni–Fe–O nanowire network catalyzing oxygen evolution and overall water splitting. Adv. Energy Mater. 8, 1701347 (2018).

    Article  Google Scholar 

  35. Wang, D. et al. Fe–N4 and Co–N4 dual sites for boosting oxygen electroreduction in Zn–air batteries. J. Mater. Chem. A 9, 13678–13687 (2021).

    Article  CAS  Google Scholar 

  36. Zhang, R. et al. Edge-site engineering of defective Fe–N4 nanozymes with boosted catalase-like performance for retinal vasculopathies. Adv. Mater. 34, 2205324 (2022).

    Article  CAS  Google Scholar 

  37. Kobayashi, H., Maeda, Y. & Yanagawa, Y. Mössbauer spectra of iron tetraphenylporphins. Bull. Chem. Soc. Jpn. 43, 2342–2346 (1970).

    Article  CAS  Google Scholar 

  38. Genoux, A. et al. Well-defined iron sites in crystalline carbon nitride. J. Am. Chem. Soc. 145, 20739–20744 (2023).

    Article  CAS  PubMed  Google Scholar 

  39. Zhu, K. et al. Unraveling the role of interfacial water structure in electrochemical semihydrogenation of alkynes. ACS Catal. 12, 4840–4847 (2022).

    Article  CAS  Google Scholar 

  40. Xu, M. et al. Atomically dispersed Cu sites on dual-mesoporous N-doped carbon for efficient ammonia electrosynthesis from nitrate. ChemSusChem 15, e202200231 (2022).

    Article  CAS  PubMed  Google Scholar 

  41. Wu, Z.-Y. et al. Electrochemical ammonia synthesis via nitrate reduction on Fe single atom catalyst. Nat. Commun. 12, 2870 (2021).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  42. Lin, G. et al. 3D porphyrin-based covalent organic frameworks. J. Am. Chem. Soc. 139, 8705–8709 (2017).

    Article  CAS  PubMed  Google Scholar 

  43. Ren, W.-X. et al. A covalent organic framework with a self-contained light source for photodynamic therapy. Chem. Commun. 58, 5245–5248 (2022).

    Article  CAS  Google Scholar 

  44. Liu, X. et al. Carbon nanotubes with fluorine-rich surface as metal-free electrocatalyst for effective synthesis of urea from nitrate and CO2. Appl. Catal. B 316, 121618 (2022).

    Article  CAS  Google Scholar 

  45. Liu, S. et al. AuCu nanofibers for electrosynthesis of urea from carbon dioxide and nitrite. Cell Rep. Phys. Sci. 3, 100869 (2022).

    Article  CAS  Google Scholar 

  46. Zhang, D., Xue, Y., Zheng, X., Zhang, C. & Li, Y. Multi-heterointerfaces for selective and efficient urea production. Natl Sci. Rev. 10, nwac209 (2023).

    Article  CAS  PubMed  Google Scholar 

  47. Yuan, M. et al. Unveiling electrochemical urea synthesis by co-activation of CO2 and N2 with Mott–Schottky heterostructure catalysts. Angew. Chem. Int. Ed. 60, 10910–10918 (2021).

    Article  CAS  Google Scholar 

  48. Yuan, M. et al. Highly selective electroreduction of N2 and CO2 to urea over artificial frustrated Lewis pairs. Energy Environ. Sci. 14, 6605–6615 (2021).

    Article  CAS  Google Scholar 

  49. Yuan, M. et al. Host–guest molecular interaction promoted urea electrosynthesis over a precisely designed conductive metal–organic framework. Energy Environ. Sci. 15, 2084–2095 (2022).

    Article  CAS  Google Scholar 

  50. Yu, Y. et al. Activation of Ga liquid catalyst with continuously exposed active sites for electrocatalytic C–N coupling. Angew. Chem. Int. Ed. 63, e202402236 (2024).

    Article  CAS  Google Scholar 

  51. Zhao, Y. et al. Efficient urea electrosynthesis from carbon dioxide and nitrate via alternating Cu–W bimetallic C–N coupling sites. Nat. Commun. 14, 4491 (2023).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  52. Luo, Y. et al. Selective electrochemical synthesis of urea from nitrate and CO2 via relay catalysis on hybrid catalysts. Nat. Catal. 6, 939–948 (2023).

    Article  CAS  Google Scholar 

  53. Gao, Y. et al. Tandem catalysts enabling efficient C–N coupling toward the electrosynthesis of urea. Angew. Chem. Int. Ed. 63, e202402215 (2024).

    Article  CAS  Google Scholar 

  54. Liu, Y. et al. C-bound or O-bound surface: which one boosts electrocatalytic urea synthesis? Angew. Chem. Int. Ed. 62, e202300387 (2023).

    Article  CAS  Google Scholar 

  55. Xu, M. et al. Kinetically matched C–N coupling toward efficient urea electrosynthesis enabled on copper single-atom alloy. Nat. Commun. 14, 6994 (2023).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

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Acknowledgements

This work was financially supported by the National Key R&D Program of China (2021YFA1501501, 2021YFA1200402 and 2022YFE0113800), the National Natural Science Foundation of China (22331007, 22375179 and 223B2117), the Key Project of Basic Research of Shanghai (22JC1402000), and a start-up grant (project number 2019125016829) from Zhejiang University of Technology. Y.Z. acknowledges the National Natural Science Foundation of China (22075250, 22122505, 21771161). W.Y. acknowledges the University Leading Talents Program of Zhejiang Province (4095C502222140203). We gratefully acknowledge the staff of BL16B1 at the Shanghai Synchrotron Light Source for their assistance with the synchrotron radiation measurements.

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Author notes

  1. These authors contributed equally: Chengtao Gong, Yongwu Peng, Mengqiu Xu, Xiaofei Wei.

Authors and Affiliations

  1. College of Materials Science and Engineering and College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, People’s Republic of China

    Chengtao Gong, Yongwu Peng, Guan Sheng, Jialiang Liu & Yihan Zhu

  2. College of Material, Chemistry and Chemical Engineering, Key Laboratory of Organosilicon Chemistry and Material Technology, Ministry of Education, Hangzhou Normal University, Hangzhou, People’s Republic of China

    Mengqiu Xu & Wei Ye

  3. School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao, People’s Republic of China

    Xiaofei Wei & Fangna Dai

  4. School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, People’s Republic of China

    Xiaowei Wu, Xing Han, Jinqiao Dong & Yong Cui

  5. Stoddart Institute of Molecular Science, Department of Chemistry, State Key Laboratory of Silicon and Advanced Semiconductor Materials, Zhejiang University, Hangzhou, People’s Republic of China

    Zhijie Chen

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Contributions

Y.C. and Y.P. conceived and designed the research project. C.G. designed, synthesized and characterized the materials. G.S. and Y.Z. performed low-dose cryo-EM measurements. M.X. and W.Y. conducted the catalytic experiments. X. Wei. and F.D. performed the theoretical calculations. J.L. assisted in the conduct of the experiment. X. Wu., X.H., J.D. and Z.C. helped with discussion of the paper. C.G., M.X., X. Wei., W.Y., Y.P. and Y.C. co-wrote and revised the paper. All authors contributed to this work and read the paper.

Corresponding authors

Correspondence to Yongwu Peng, Yihan Zhu, Wei Ye or Yong Cui.

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Nature Synthesis thanks the anonymous reviewers for their contribution to the peer review of this work. Primary Handling Editor: Alison Stoddart, in collaboration with the Nature Synthesis team.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–127, Discussion and Tables 1–10.

Supplementary Video 1

Assembly and metallization of PCOF-34.

Supplementary Video 2

Electrocatalytic urea synthesis processes via twin iron sites.

Supplementary Data 1

Structure model data for PCOF-34-Fe, CCDC 2345501.

Supplementary Data 2

Structure model data for PCOF-90-Fe, CCDC 2345502.

Supplementary Data 3

Structure model data for PCOF-34, CCDC 2345503.

Supplementary Data 4

Structure model data for PCOF-90, CCDC 2345504.

Source data

Source Data Fig. 1

Source data for Fig. 1.

Source Data Fig. 2

Source data for Fig. 2.

Source Data Fig. 3

Source data for Fig. 3.

Source Data Fig. 4

Source data for Fig. 4.

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Gong, C., Peng, Y., Xu, M. et al. Selective electrocatalytic synthesis of urea using entangled iron porphyrins in covalent organic frameworks. Nat. Synth 4, 720–729 (2025). https://doi.org/10.1038/s44160-025-00742-6

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