Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Efficient water oxidation catalysts based on readily available iron coordination complexes


Water oxidation catalysis constitutes the bottleneck for the development of energy-conversion schemes based on sunlight. To date, state-of-the-art homogeneous water oxidation catalysis is performed efficiently with expensive, toxic and earth-scarce transition metals, but 3d metal-based catalysts are much less established. Here we show that readily available, environmentally benign iron coordination complexes catalyse homogeneous water oxidation to give O2, with high efficiency during a period of hours. Turnover numbers >350 and >1,000 were obtained using cerium ammonium nitrate at pH 1 and sodium periodate at pH 2, respectively. Spectroscopic monitoring of the catalytic reactions, in combination with kinetic studies, show that high valent oxo-iron species are responsible for the O–O forming event. A systematic study of iron complexes that contain a broad family of neutral tetradentate organic ligands identifies first-principle structural features to sustain water oxidation catalysis. Iron-based catalysts described herein open a novel strategy that could eventually enable sustainable artificial photosynthetic schemes.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Transition metal complexes used in this study.
Figure 2: TON versus time.
Figure 3: Oxygen formation and cerium(IV) consumption monitored on-line by a pressure transducer and UV-vis spectrometry.
Figure 4: Postulated mechanism for water oxidation by iron complexes based on tetradentate nitrogen ligands.


  1. 1

    US Energy Information Administration. International Energy Outlook DOE/EIA-0484 (Office of Integrated Analysis and Forecasting, US Department of Energy).

  2. 2

    Hoffert, M. I. et al. Energy implications of future stabilization of atmospheric CO2 content. Nature 395, 881–884 (1998).

    CAS  Article  Google Scholar 

  3. 3

    Lewis, N. S. Energy and Transportation 33–39 (The National Academies Press, 2003).

    Google Scholar 

  4. 4

    Ciamician, G. The photochemistry of the future. Science 36, 385–394 (1912).

    CAS  Article  Google Scholar 

  5. 5

    Turner, J. A. Sustainable hydrogen production. Science 305, 972–974 (2004).

    CAS  Article  Google Scholar 

  6. 6

    Dempsey, J. L. et al. Molecular chemistry of consequence to renewable energy. Inorg. Chem. 44, 6879–6892 (2005).

    CAS  Article  Google Scholar 

  7. 7

    Yano, J. et al. Where water is oxidized to dioxygen: structure of the photosynthetic Mn4Ca cluster. Science 314, 821–825 (2006).

    CAS  Article  Google Scholar 

  8. 8

    Chen, X., Shen, S., Guo, L. & Mao, S. S. Semiconductor-based photocatalytic hydrogen generation. Chem. Rev. 110, 6503–6570 (2010).

    CAS  Article  Google Scholar 

  9. 9

    Magnuson A. et al. Biomimetic and microbial approaches to solar fuel generation. Acc. Chem. Res. 42, 1899–1909 (2009).

    CAS  Article  Google Scholar 

  10. 10

    Tong, L., Duan, L., Xu, Y., Privalov, T. & Sun, L. Structural modifications of mononuclear ruthenium complexes: a combined experimental and theoretical study on the kinetics of ruthenium-catalyzed water oxidation. Angew. Chem. Int. Ed. 50, 445–449 (2011).

    CAS  Article  Google Scholar 

  11. 11

    McDaniel, N. D., Coughlin, F. J., Tinker, L. L. & Bernhard, S. Cyclometalated iridium(III) aquo complexes: efficient and tunable catalysts for the homogeneous oxidation of water. J. Am. Chem. Soc. 130, 210–217 (2008).

    CAS  Article  Google Scholar 

  12. 12

    Hull, J. F. et al. Highly active and robust Cp* iridium complexes for catalytic water oxidation. J. Am. Chem. Soc. 131, 8730–8731 (2009).

    CAS  Article  Google Scholar 

  13. 13

    Lalrempuia, R., McDaniel, N. D., Müller-Bunz, H., Bernhard, S. & Albrecht, M. Water oxidation catalyzed by strong carbene-type donor–ligand complexes of iridium. Angew. Chem. Int. Ed. 49, 9765–9768 (2010).

    CAS  Article  Google Scholar 

  14. 14

    Enthaler, S., Junge, K. & Beller, M. Sustainable metal catalysis with iron: from rust to a rising star? Angew. Chem. Int. Ed. 47, 3317–3321 (2008).

    CAS  Article  Google Scholar 

  15. 15

    Ruettinger, W. F., Campana, C. & Dismukes, G. C. Synthesis and characterization of Mn4O4L6 complexes with cubane-like core structure: a new class of models of the active site of the photosynthetic water oxidase. J. Am. Chem. Soc. 119, 6670–6671 (1997).

    CAS  Article  Google Scholar 

  16. 16

    Brimblecombe, R., Swiegers, G. F., Dismukes, G. C. & Spiccia, L. Sustained water oxidation photocatalysis by a bioinspired manganese cluster. Angew. Chem. Int. Ed. 47, 7335–7338 (2008).

    CAS  Article  Google Scholar 

  17. 17

    Dismukes, G. C. et al. Development of bioinspired Mn4O4-cubane water oxidation catalysts: lessons from photosynthesis. Acc. Chem. Res. 42, 1935–1943 (2009).

    CAS  Article  Google Scholar 

  18. 18

    Limburg, J. et al. A functional model for O–O bond formation by the O2-evolving complex in photosystem II. Science 283, 1524–1527 (1999).

    CAS  Article  Google Scholar 

  19. 19

    Kanan, M. W. & Nocera, D. G. In situ formation of an oxygen-evolving catalyst in neutral water containing phosphate and Co2+. Science 321, 1072–1075 (2008).

    CAS  Article  Google Scholar 

  20. 20

    Yin, Q. et al. A fast soluble carbon-free molecular water oxidation catalyst based on abundant metals. Science 328, 342–345 (2010).

    CAS  Article  Google Scholar 

  21. 21

    Huang, Z. et al. Efficient light-driven carbon-free cobalt-based molecular catalyst for water oxidation. J. Am. Chem. Soc. 133, 2068–2071 (2011).

    CAS  Article  Google Scholar 

  22. 22

    Ellis, W. C., McDaniel, N. D., Bernhard, S. & Collins, T. J. Fast water oxidation using iron. J. Am. Chem. Soc. 132, 10990–10991 (2010).

    CAS  Article  Google Scholar 

  23. 23

    Company, A. et al. Alkane hydroxylation by a nonheme iron catalyst that challenges the heme paradigm for oxygenase action. J. Am. Chem. Soc. 129, 15766–15767 (2007).

    CAS  Article  Google Scholar 

  24. 24

    Company, A. et al. Modeling the cis-oxo-labile binding site motif of non-heme iron oxygenases: water exchange and oxidation reactivity of a non-heme iron(IV)–oxo compound bearing a tripodal tetradentate ligand. Chem. Eur. J. 17, 1622–1634 (2011).

    CAS  Article  Google Scholar 

  25. 25

    Garcia-Bosch, I. et al. Evidence for a precursor complex in C–H hydrogen atom transfer reactions mediated by a manganese(IV)–oxo complex. Angew. Chem. Int. Ed. 50, 5648–5653 (2011).

    CAS  Article  Google Scholar 

  26. 26

    Fukuzumi, S. et al. Crystal structure of a metal ion-bound oxoiron(IV) complex and implications for biological electron transfer. Nature Chem. 2, 756–759 (2010).

    CAS  Article  Google Scholar 

  27. 27

    Morimoto, Y. et al. Metal ion-coupled electron transfer of a nonheme oxoiron(IV) complex: remarkable enhancement of electron-transfer rates by Sc3+. J. Am. Chem. Soc. 133, 403–405 (2011).

    CAS  Article  Google Scholar 

  28. 28

    Chen, Z. et al. Nonaqueous catalytic water oxidation. J. Am. Chem. Soc. 135, 17670–17673 (2010).

    Article  Google Scholar 

  29. 29

    Fukuzumi, S., Kotani, H., Lee, Y-M. & Nam, W. Sequential electron-transfer and proton-transfer pathways in hydride-transfer reactions from dihydronicotinamide adenine dinucleotide analogues to non-heme oxoiron(IV) complexes and p-chloranil. Detection of radical cations of NADH analogues in acid-promoted hydride-transfer reactions. J. Am. Chem. Soc. 130, 15134–15142 (2008).

    CAS  Article  Google Scholar 

  30. 30

    Comba, P., Fukuzumi, S., Kotani, H. & Wunderlich, S. Electron-transfer properties of an efficient nonheme iron oxidation catalyst with a tetradentate bispidine ligand. Angew. Chem. Int. Ed. 49, 2622–2625 (2010).

    CAS  Article  Google Scholar 

  31. 31

    Wang, D., Zhang, M., Bühlmann, P. & Que, L. Jr Redox potential and C–H bond cleaving properties of a nonheme Fe(IV)=O complex in aqueous solution. J. Am. Chem. Soc. 132, 7638–7644 (2010).

    CAS  Article  Google Scholar 

  32. 32

    Jensen, M. P. et al. High-valent nonheme iron. Two distinct iron(IV) species derived from a common iron(II) precursor. J. Am. Chem. Soc. 127, 10512–10525 (2005).

    CAS  Article  Google Scholar 

  33. 33

    Company, A. et al. Olefin-dependent discrimination between two nonheme HOFe(V)=O tautomeric species in catalytic H2O2 epoxidations. Chem. Eur. J. 15, 3359–3362 (2009).

    CAS  Article  Google Scholar 

  34. 34

    Bassan, A., Blomberg, M. R. A., Siegbahn, P. E. M. & Que, L. Jr A density functional study of O–O bond cleavage for a biomimetic non-heme iron complex demonstrating an FeV-intermediate. J. Am. Chem. Soc. 124, 11056–11063 (2002).

    CAS  Article  Google Scholar 

  35. 35

    Quinonero, D., Morokuma, K., Musaev, D. G., Mas-Balleste, R. & Que, L. Jr Metal–peroxo versus metal–oxo oxidants in non-heme iron-catalyzed olefin oxidations: computational and experimental studies on the effect of water. J. Am. Chem. Soc. 127, 6548–6549 (2005).

    CAS  Article  Google Scholar 

  36. 36

    Dau, H. et al. The mechanism of water oxidation: from electrolysis via homogeneous to biological catalysis. ChemCatChem 2, 724–761 (2010).

    CAS  Article  Google Scholar 

  37. 37

    Garcia-Bosch, I., Company, A., Fontrodona, X., Ribas, X. & Costas, M. Efficient and selective peracetic acid epoxidation catalyzed by a robust manganese catalyst. Org. Lett. 10, 2095–2098 (2008).

    CAS  Article  Google Scholar 

  38. 38

    Costas, M. & Que, L. Jr Ligand topology tuning of iron-catalyzed hydrocarbon oxidations. Angew. Chem. Int. Ed. 41, 2179–2181 (2002).

    CAS  Article  Google Scholar 

  39. 39

    Suzuki, K., Oldenburg, P. D. & Que L. Jr Iron-catalyzed asymmetric olefin cis-dihydroxylation with 97% enantiomeric excess. Angew. Chem. Int. Ed. 47, 1887–1889 (2008).

    CAS  Article  Google Scholar 

  40. 40

    Britovsek, G. J. P., England, J. & White, A. J. P. Non-heme iron(II) complexes containing tripodal tetradentate nitrogen ligands and their application in alkane oxidation catalysis. Inorg. Chem. 44, 8125–8134 (2005).

    CAS  Article  Google Scholar 

  41. 41

    Lim, M. H. et al. An FeIV=O complex of a tetradentate tripodal nonheme ligand. Proc. Natl Acad. Sci. USA 100, 3665–3670 (2003).

    CAS  Article  Google Scholar 

  42. 42

    Nam, W., Ho, R. Y. N. & Valentine, J. S. Iron–cyclam complexes as catalysts for the epoxidation of olefins by 30% aqueous hydrogen peroxide in acetonitrile and methanol. J. Am. Chem. Soc. 113, 7052–7054 (1991).

    CAS  Article  Google Scholar 

  43. 43

    Roelfes, G. et al. End-on and side-on peroxo derivatives of non-heme iron complexes with pentadentate ligands: models for putative intermediates in biological iron/dioxygen chemistry. Inorg. Chem. 42, 2639–2653 (2003).

    CAS  Article  Google Scholar 

Download references


We thank R. Hage, X. Ribas and P. Lahuerta for reading this work and for comments. We thank the European Research Foundation for project FP7-PEOPLE-2010-ERG-268445 (J.Ll.), El Ministerio de Ciencia e Innovación for project CTQ2009-08464 (M.C.), for a Ramon y Cajal contract (J.Ll.) and for a PhD grant (I.G-B.), Generalitat de Catalunya for an ICREA Academia Award and the European Research Council for Project ERC-2009-StG-239910 (M.C.). RahuCat is acknowledged for giving the tritosylTACN.

Author information




J.Ll. and M.C. devised the initial concept for the work and designed the experiments. Z.C., I.G-B., L.G. and J.Ll. carried out the experiments. J.J.P. and J.Ll. designed the differential pressure transducer hardware and software. Z.C., I.G-B. and J.Ll. analysed the data. J.Ll. and M.C. co-wrote the manuscript.

Corresponding authors

Correspondence to Julio Lloret Fillol or Miquel Costas.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary information

Supplementary information (PDF 2359 kb)

Supplementary information

Supplementary Movie S1 (MP4 13596 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Fillol, J., Codolà, Z., Garcia-Bosch, I. et al. Efficient water oxidation catalysts based on readily available iron coordination complexes. Nature Chem 3, 807–813 (2011).

Download citation

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing