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Identifying high-spin hydroxyl-coordinated Fe3+N4 as the active centre for acidic oxygen reduction using molecular model catalysts

Nature Catalysis volume 8, pages 422–435 (2025)Cite this article

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Abstract

Fe–N–C catalysts are the most promising alternative to Pt for the acidic oxygen reduction reaction (ORR), yet the electronic structure of their active centres remains elusive. Here we synthesize and characterize a conjugate-bridged iron phthalocyanine (FePc) dimer model catalyst with identical Fe sites and catalytic activity comparable to actual catalysts. A high-spin trivalent FeN4 with an axial hydroxyl ligand, denoted as OH–Fe3+N4 (S = 5/2), is identified as the active state. By contrast, monomer and non-conjugated dimer manifest the OH–Fe3+N4 (S = 3/2) state with an excessive adsorption energy of ORR intermediates. Polymerized FePc is composed of 35% of the S = 5/2 state and 65% of the Fe2+N4 (S = 0 or 1) state, showing a general weaker adsorption energy. Both overly strong and weak adsorption energy hinder the ORR. Theoretical calculations indicate that π–d interaction between Fe and the conjugated carbon plane dictates the spin state. This study will help to precisely design Fe-based ORR catalysts.

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Fig. 1: Synthesis and characterization of FePc=FePc.
Fig. 2: Spin and ORR behaviours of FePc=FePc.
Fig. 3: Characterization of five molecular catalysts.
Fig. 4: Spin of five molecular catalysts.
Fig. 5: Electrochemical behaviours of different spin states.
Fig. 6: Theoretical calculations.

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Data availability

Data for Figs. 1b,d–g, 2a–f, 3c–h, 4a–d, 5a–c and 6a–e,g and the atomic coordinates of the optimized computational models are available via Figshare at https://doi.org/10.6084/m9.figshare.28465688 (ref. 82). Supplementary Figs. 1–19 will be made available upon request to the corresponding authors. Source data are provided with this paper.

References

  1. Xu, L. et al. Formation of active sites on transition metals through reaction-driven migration of surface atoms. Science 380, 70–76 (2023).

    Article  CAS  PubMed  Google Scholar 

  2. Vogt, C. & Weckhuysen, B. M. The concept of active site in heterogeneous catalysis. Nat. Rev. Chem. 6, 89–111 (2022).

    Article  PubMed  Google Scholar 

  3. Gu, J., Hsu, C.-S., Bai, L., Chen, H. M. & Hu, X. Atomically dispersed Fe3+ sites catalyze efficient CO2 electroreduction to CO. Science 364, 1091–1094 (2019).

    Article  CAS  PubMed  Google Scholar 

  4. Li, R. & Wang, D. Understanding the structure–performance relationship of active sites at atomic scale. Nano Res. 15, 6888–6923 (2022).

    Article  CAS  Google Scholar 

  5. Lu, B., Liu, Q. & Chen, S. Electrocatalysis of single-atom sites: impacts of atomic coordination. ACS Catal. 10, 7584–7618 (2020).

    Article  CAS  Google Scholar 

  6. Cao, L. et al. Identification of single-atom active sites in carbon-based cobalt catalysts during electrocatalytic hydrogen evolution. Nat. Catal. 2, 134–141 (2019).

    Article  CAS  Google Scholar 

  7. Giulimondi, V., Mitchell, S. & Pérez-Ramírez, J. Challenges and opportunities in engineering the electronic structure of single-atom catalysts. ACS Catal. 13, 2981–2997 (2023).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  8. Liu, K. et al. Insights into the activity of single-atom Fe–N–C catalysts for oxygen reduction reaction. Nat. Commun. 13, 2075 (2022).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  9. Zhuo, H.-Y. et al. Theoretical understandings of graphene-based metal single-atom catalysts: stability and catalytic performance. Chem. Rev. 120, 12315–12341 (2020).

    Article  CAS  PubMed  Google Scholar 

  10. Mehmood, A. et al. High loading of single atomic iron sites in Fe–NC oxygen reduction catalysts for proton exchange membrane fuel cells. Nat. Catal. 5, 311–323 (2022).

    Article  CAS  Google Scholar 

  11. Wan, X. et al. Fe–N–C electrocatalyst with dense active sites and efficient mass transport for high-performance proton exchange membrane fuel cells. Nat. Catal. 2, 259–268 (2019).

    Article  CAS  Google Scholar 

  12. Jiao, L. et al. Chemical vapour deposition of Fe–N–C oxygen reduction catalysts with full utilization of dense Fe–N4 sites. Nat. Mater. 20, 1385–1391 (2021).

    Article  CAS  PubMed  Google Scholar 

  13. Jin, Z. et al. Understanding the inter-site distance effect in single-atom catalysts for oxygen electroreduction. Nat. Catal. 4, 615–622 (2021).

    Article  CAS  Google Scholar 

  14. Chung, H. T. et al. Direct atomic-level insight into the active sites of a high-performance PGM-free ORR catalyst. Science 357, 479–484 (2017).

    Article  CAS  PubMed  Google Scholar 

  15. Li, J. et al. Identification of durable and non-durable FeNx sites in Fe–N–C materials for proton exchange membrane fuel cells. Nat. Catal. 4, 10–19 (2021).

    Article  Google Scholar 

  16. Zitolo, A. et al. Identification of catalytic sites for oxygen reduction in iron- and nitrogen-doped graphene materials. Nat. Mater. 14, 937–942 (2015).

    Article  CAS  PubMed  Google Scholar 

  17. Zhang, Z. et al. Regulating spin states in oxygen electrocatalysis. Angew. Chem. Int. Ed. 62, e202216837 (2023).

    Article  CAS  Google Scholar 

  18. Ni, L. et al. Identification of the catalytically dominant iron environment in iron- and nitrogen-doped carbon catalysts for the oxygen reduction reaction. J. Am. Chem. Soc. 144, 16827–16840 (2022).

    Article  CAS  PubMed  Google Scholar 

  19. Kramm, U. I., Lefèvre, M., Bogdanoff, P., Schmeißer, D. & Dodelet, J.-P. Analyzing structural changes of Fe–N–C cathode catalysts in PEM fuel cell by Mößbauer spectroscopy of complete membrane electrode assemblies. J. Phys. Chem. Lett. 5, 3750–3756 (2014).

    Article  CAS  PubMed  Google Scholar 

  20. Chen, Z. et al. Unraveling the origin of sulfur-doped Fe–N–C single-atom catalyst for enhanced oxygen reduction activity: effect of iron spin-state tuning. Angew. Chem. Int. Ed. 60, 25404–25410 (2021).

    Article  CAS  Google Scholar 

  21. Wei, X. et al. Tuning the spin state of Fe single atoms by Pd nanoclusters enables robust oxygen reduction with dissociative pathway. Chem 9, 181–197 (2023).

    Article  CAS  Google Scholar 

  22. Zhao, K.-M. et al. Insight into the mechanism of axial ligands regulating the catalytic activity of Fe–N4 sites for oxygen reduction reaction. Adv. Energy Mater. 12, 2103588 (2022).

    Article  CAS  Google Scholar 

  23. Liu, S. et al. Atomically dispersed iron sites with a nitrogen–carbon coating as highly active and durable oxygen reduction catalysts for fuel cells. Nat. Energy 7, 652–663 (2022).

    Article  CAS  Google Scholar 

  24. Cai, H. et al. Highly active sites of low spin FeIIN4 species: the identification and the ORR performance. Nano Res. 14, 122–130 (2021).

    Article  CAS  Google Scholar 

  25. Yang, G. et al. Regulating Fe-spin state by atomically dispersed Mn–N in Fe–N–C catalysts with high oxygen reduction activity. Nat. Commun. 12, 1734 (2021).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  26. Fei, H. et al. General synthesis and definitive structural identification of MN4C4 single-atom catalysts with tunable electrocatalytic activities. Nat. Catal. 1, 63–72 (2018).

    Article  CAS  Google Scholar 

  27. Guo, D. et al. Active sites of nitrogen-doped carbon materials for oxygen reduction reaction clarified using model catalysts. Science 351, 361–365 (2016).

    Article  CAS  PubMed  Google Scholar 

  28. Boudart, M. Model catalysts: reductionism for understanding. Top. Catal. 13, 147–149 (2000).

    Article  CAS  Google Scholar 

  29. Yang, X.-D. et al. Modeling Fe/N/C catalysts in monolayer graphene. ACS Catal. 7, 139–145 (2017).

    Article  CAS  Google Scholar 

  30. Li, W., Yu, A., Higgins, D. C., Llanos, B. G. & Chen, Z. Biologically inspired highly durable iron phthalocyanine catalysts for oxygen reduction reaction in polymer electrolyte membrane fuel cells. J. Am. Chem. Soc. 132, 17056–17058 (2010).

    Article  CAS  PubMed  Google Scholar 

  31. Bhunia, S., Ghatak, A., Rana, A. & Dey, A. Amine groups in the second sphere of iron porphyrins allow for higher and selective 4e−/4H+ oxygen reduction rates at lower overpotentials. J. Am. Chem. Soc. 145, 3812–3825 (2023).

    Article  CAS  PubMed  Google Scholar 

  32. Marshall-Roth, T. et al. A pyridinic Fe-N4 macrocycle models the active sites in Fe/N-doped carbon electrocatalysts. Nat. Commun. 11, 5283 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  33. Deng, D. et al. A single iron site confined in a graphene matrix for the catalytic oxidation of benzene at room temperature. Sci. Adv. 1, e1500462 (2015).

    Article  PubMed  PubMed Central  Google Scholar 

  34. Vujačić, A., Bugarčić, Ž. D., Schiller, J., Vasić, V. & Petković, M. Matrix-assisted laser desorption and ionisation time-of-flight mass spectrometry of Pt(II) and Pd(II) complexes. Polyhedron 28, 2905–2912 (2009).

    Article  Google Scholar 

  35. Cook, P. L., Liu, X., Yang, W. & Himpsel, F. J. X-ray absorption spectroscopy of biomimetic dye molecules for solar cells. J. Chem. Phys. 131, 194701 (2009).

    Article  PubMed  Google Scholar 

  36. Alsudairi, A. et al. Resolving the iron phthalocyanine redox transitions for ORR catalysis in aqueous media. J. Phys. Chem. Lett. 8, 2881–2886 (2017).

    Article  CAS  PubMed  Google Scholar 

  37. Wagner, S. et al. Elucidating the structural composition of an Fe–N–C catalyst by nuclear- and electron-resonance techniques. Angew. Chem. Int. Ed. 58, 10486–10492 (2019).

    Article  CAS  Google Scholar 

  38. Mineva, T. et al. Understanding active sites in pyrolyzed Fe–N–C catalysts for fuel cell cathodes by bridging density functional theory calculations and 57Fe mössbauer spectroscopy. ACS Catal. 9, 9359–9371 (2019).

    Article  CAS  Google Scholar 

  39. Bletsa, E., Solakidou, M., Louloudi, M. & Deligiannakis, Y. Ambient O2 is a switch between [1-electron/1-radical] vs. [2–electron] oxidative catalytic path in Fe-phthalocyanines. Chem. Phys. Lett. 743, 137180 (2020).

    Article  CAS  Google Scholar 

  40. Kobayashi, N., Shirai, H. & Hojo, N. Iron(III) phthalocyanines: oxidation and spin states of iron in iron phthalocyanines with carboxyl groups. J. Chem. Soc. Dalton Trans. 1984, 2107–2110 (1984).

    Article  Google Scholar 

  41. Bominaar, E. L. et al. Structural, Moessbauer, and EPR investigations on two oxidation states of a five-coordinate, high-spin synthetic heme. Quantitative interpretation of zero-field parameters and large quadrupole splitting. Inorg. Chem. 31, 1845–1854 (1992).

    Article  CAS  Google Scholar 

  42. Shiroka, T. Introduction to solid state physics. Contemp. Phys. 61, 221–222 (2020).

    Article  Google Scholar 

  43. Hutchison, P., Kaminsky, C. J., Surendranath, Y. & Hammes-Schiffer, S. Concerted proton-coupled electron transfer to a graphite adsorbed metalloporphyrin occurs by band to bond electron redistribution. ACS Cent. Sci. 9, 927–936 (2023).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  44. Wan, L. et al. Molecular degradation of iron phthalocyanine during the oxygen reduction reaction in acidic media. ACS Catal. 12, 11097–11107 (2022).

    Article  CAS  Google Scholar 

  45. Li, X. & Xiang, Z. Identifying the impact of the covalent-bonded carbon matrix to FeN4 sites for acidic oxygen reduction. Nat. Commun. 13, 57 (2022).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  46. Bai, L., Hsu, C.-S., Alexander, D. T. L., Chen, H. M. & Hu, X. A cobalt–iron double-atom catalyst for the oxygen evolution reaction. J. Am. Chem. Soc. 141, 14190–14199 (2019).

    Article  CAS  PubMed  Google Scholar 

  47. Deng, D. et al. Catalysis with two-dimensional materials and their heterostructures. Nat. Nanotech. 11, 218–230 (2016).

    Article  CAS  Google Scholar 

  48. Peng, P. et al. In situ charge exfoliated soluble covalent organic framework directly used for Zn-air flow battery. ACS Nano 13, 878–884 (2019).

    Article  PubMed  Google Scholar 

  49. Peng, P. et al. A pyrolysis-free path toward superiorly catalytic nitrogen-coordinated single atom. Sci. Adv. 5, eaaw2322 (2019).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  50. Burattini, S. et al. A healable supramolecular polymer blend based on aromatic π-π stacking and hydrogen bonding interactions. J. Am. Chem. Soc. 143, 10016–10017 (2021).

    Article  CAS  PubMed  Google Scholar 

  51. Hocking, R. K. et al. Fe L-edge X-ray absorption spectroscopy of low-spin Heme relative to non-heme Fe complexes: delocalization of Fe d-electrons into the porphyrin ligand. J. Am. Chem. Soc. 129, 113–125 (2007).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  52. Nematollahi, P. et al. Identification of a robust and durable FeN4Cx catalyst for ORR in PEM fuel cells and the role of the fifth ligand. ACS Catal. 12, 7541–7549 (2022).

    Article  CAS  Google Scholar 

  53. Li, G. et al. Revealing surface fine structure on PtAu catalysts by an in situ ATR-SEIRAS CO-probe method. J. Mater. Chem. A 11, 14043–14051 (2023).

    Article  CAS  Google Scholar 

  54. Kunimatsu, K., Golden, W. G., Seki, H. & Philpott, M. R. Carbon monoxide adsorption on a platinum electrode studied by polarization modulated FT-IRRAS. 1. CO adsorbed in the double-layer potential region and its oxidation in acids. Langmuir 1, 245–250 (1985).

    Article  CAS  Google Scholar 

  55. Gomez, R., Rodes, A., Perez, J. M., Feliu, J. M. & Aldaz, A. Electrochemical and in situ FTIR studies of the CO adsorption at palladium and rhodium multilayers deposited on platinum single crystal surfaces. I. Pt(110) substrate. Surf. Sci. 327, 202–215 (1995).

    Article  CAS  Google Scholar 

  56. Wasileski, S. A., Koper, M. T. M. & Weaver, M. J. Field-dependent chemisorption of carbon monoxide on platinum-group (111) surfaces: relationships between binding energetics, geometries, and vibrational properties as assessed by density functional theory. J. Phys. Chem. B 105, 3518–3530 (2001).

    Article  CAS  Google Scholar 

  57. Medford, A. J. et al. From the Sabatier principle to a predictive theory of transition-metal heterogeneous catalysis. J. Catal. 328, 36–42 (2015).

    Article  CAS  Google Scholar 

  58. Meng, H., Jaouen, F., Proietti, E., Lefevre, M. & Dodelet, J.-P. pH-effect on oxygen reduction activity of Fe-based electro-catalysts. Electrochem. Commun. 11, 1986–1989 (2009).

    Article  CAS  Google Scholar 

  59. Ramaswamy, N. & Mukerjee, S. Influence of inner- and outer-sphere electron transfer mechanisms during electrocatalysis of oxygen reduction in alkaline media. J. Phys. Chem. C 115, 18015–18026 (2011).

    Article  CAS  Google Scholar 

  60. Ylvisaker, E. R., Pickett, W. E. & Koepernik, K. Anisotropy and magnetism in the LSDA plus U method. Phys. Rev. B 79, 035103 (2009).

    Article  Google Scholar 

  61. Solovyev, I. V., Dederichs, P. H. & Anisimov, V. I. Corrected atomic limit in the local-density approximation and the electronic structure of d impurities in Rb. Phys. Rev. B 50, 16861–16871 (1994).

    Article  CAS  Google Scholar 

  62. Xu, H., Cheng, D., Cao, D. & Zeng, X. C. Revisiting the universal principle for the rational design of single-atom electrocatalysts. Nat. Catal. 7, 207–218 (2024).

    Article  CAS  Google Scholar 

  63. Jensen, K. P. Bioinorganic chemistry modeled with the TPSSh density functional. Inorg. Chem. 47, 10357–10365 (2008).

    Article  CAS  PubMed  Google Scholar 

  64. Weymuth, T., Couzijn, E. P. A., Chen, P. & Reiher, M. New benchmark set of transition-metal coordination reactions for the assessment of density functionals. J. Chem. Theory Comput. 10, 3092–3103 (2014).

    Article  CAS  PubMed  Google Scholar 

  65. Maurer, L. R., Bursch, M., Grimme, S. & Hansen, A. Assessing density functional theory for chemically relevant open-shell transition metal reactions. J. Chem. Theory Comput. 17, 6134–6151 (2021).

    Article  CAS  PubMed  Google Scholar 

  66. Brumboiu, I. E. et al. Influence of electron correlation on the electronic structure and magnetism of transition-metal phthalocyanines. J. Chem. Theory Comput. 12, 1772–1785 (2016).

    Article  CAS  PubMed  Google Scholar 

  67. Lin, C.-Y., Zhang, L., Zhao, Z. & Xia, Z. Design principles for covalent organic frameworks as efficient electrocatalysts in clean energy conversion and green oxidizer production. Adv. Mater. 29, 1606635 (2017).

    Article  Google Scholar 

  68. Zeng, Y. et al. Tuning the thermal activation atmosphere breaks the activity–stability trade-off of Fe–N–C oxygen reduction fuel cell catalysts. Nat. Catal. 6, 1215–1227 (2023).

    Article  CAS  Google Scholar 

  69. Jiang, R., Qiao, Z., Xu, H. & Cao, D. Defect engineering of Fe–N–C single-atom catalysts for oxygen reduction reaction. Chin. J. Catal. 48, 224–234 (2023).

    Article  CAS  Google Scholar 

  70. 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 

  71. Goerigk, L. & Grimme, S. A thorough benchmark of density functional methods for general main group thermochemistry, kinetics, and noncovalent interactions. Phys. Chem. Chem. Phys. 13, 6670–6688 (2011).

    Article  CAS  PubMed  Google Scholar 

  72. VandeVondele, J. & Hutter, J. Gaussian basis sets for accurate calculations on molecular systems in gas and condensed phases. J. Chem. Phys. 127, 114105 (2007).

    Article  PubMed  Google Scholar 

  73. Weigend, F., Furche, F. & Ahlrichs, R. Gaussian basis sets of quadruple zeta valence quality for atoms H–Kr. J. Chem. Phys. 119, 12753–12762 (2003).

    Article  CAS  Google Scholar 

  74. Zhang, D. & Truhlar, D. G. Spin splitting energy of transition metals: a new, more affordable wave function benchmark method and its use to test density functional theory. J. Chem. Theory Comput. 16, 4416–4428 (2020).

    Article  CAS  PubMed  Google Scholar 

  75. Kresse, G. & Furthmuller, J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comput. Mater. Sci. 6, 15–50 (1996).

    Article  CAS  Google Scholar 

  76. Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).

    Article  CAS  PubMed  Google Scholar 

  77. Blochl, P. E. The projector-augmented wave (PAW) method and dynamical properties of organometallic compounds. Abstr. Pap. Am. Chem. Soc. 209, 115 (1995).

    Google Scholar 

  78. Pueyo Bellafont, N., Vines, F., Hieringer, W. & Illas, F. Predicting core level binding energies shifts: suitability of the projector augmented wave approach as implemented in VASP. J. Comput. Chem. 38, 518–522 (2017).

    Article  CAS  PubMed  Google Scholar 

  79. Iyemperumal, S. K. & Deskins, N. A. Evaluating solvent effects at the aqueous/Pt(111) interface. ChemPhysChem 18, 2171–2190 (2017).

    Article  CAS  PubMed  Google Scholar 

  80. Walch, S. P. Effect of solvation on the oxygen reduction reaction on Pt catalyst. J. Phys. Chem. C 115, 7377–7391 (2011).

    Article  CAS  Google Scholar 

  81. Mathew, K., Sundararaman, R., Letchworth-Weaver, K., Arias, T. A. & Hennig, R. G. Implicit solvation model for density-functional study of nanocrystal surfaces and reaction pathways. J. Chem. Phys. 140, 084106 (2014).

    Article  PubMed  Google Scholar 

  82. Zhao, K.-M. et al. Identifying high-spin hydroxyl-coordinated Fe3+N4 as the active centre for acidic oxygen reduction using molecular model catalysts. figshare https://doi.org/10.6084/m9.figshare.28465688 (2025).

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Acknowledgements

We acknowledge the staff of the Beijing Synchrotron Radiation Facility (1W1B and 4B9A, BSRF) for their support in XAS measurements. We also thank BL10B in National Synchrotron Radiation Laboratory (NSRL) for characterization by synchrotron radiation. This work was supported by National Key Research and Development Program of China (2023YFA1509000 to Y.-C.W.), National Natural Science Foundation of China (22021001 to Z.-Y.Z., 22288102 to S.-G.S. and 22179116 to Y.-C.W.), Fundamental Research Funds for the Central Universities (20720220017 to Y.-C.W.) and China Postdoctoral Science Foundation (2021M691876 to K.-M.Z.).

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  1. These authors contributed equally: Kuang-Min Zhao, Dao-Xiong Wu, Wen-Kun Wu.

Authors and Affiliations

  1. State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China

    Kuang-Min Zhao, Jia-Bao Nie, Guang Li, Hai-Yan Shi, Zhi-You Zhou, Yu-Cheng Wang & Shi-Gang Sun

  2. School of Marine Science and Engineering, Hainan University, Haikou, China

    Dao-Xiong Wu

  3. Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, USA

    Wen-Kun Wu

  4. Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Electronic Science, East China Normal University, Shanghai, China

    Fu-Shan Geng

  5. Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province, Xiamen, China

    Sheng-Chao Huang, Zhi-You Zhou & Yu-Cheng Wang

  6. Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China

    Huan Huang & Jing Zhang

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Contributions

Y.-C.W. and K.-M.Z. designed the experiments. K.-M.Z. performed majority of the experiments. D.-X.W., W.-K.W. and J.-B.N. performed the theoretical calculation. G.L. performed the infrared test. S.-C.H. conducted the AFM testing. F.-S.G. analysed the EPR data. H.-Y.S. performed the Mössbauer test. H.H. and J.Z. performed the XAS test. Y.-C.W. wrote the manuscript. Z.-Y.Z. revised the manuscript. S.-G.S. supervised this work.

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Correspondence to Yu-Cheng Wang or Shi-Gang Sun.

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Nature Catalysis thanks Esen Alp, Tzonka Mineva and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Figs. 1–19, Tables 1–6 and references.

Supplementary Data 1 (download ZIP )

Atomic coordinates of optimized structure.

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Zhao, KM., Wu, DX., Wu, WK. et al. Identifying high-spin hydroxyl-coordinated Fe3+N4 as the active centre for acidic oxygen reduction using molecular model catalysts. Nat Catal 8, 422–435 (2025). https://doi.org/10.1038/s41929-025-01324-7

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