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Atomic-scale insights into surface species of electrocatalysts in three dimensions

Abstract

The topmost atomic layers of electrocatalysts determine the mechanism and kinetics of reactions in many important industrial processes, such as water splitting, chlor-electrolysis or fuel cells. Optimizing the performance of electrocatalysts requires a detailed understanding of surface-state changes during the catalytic process, ideally at the atomic scale. Here, we use atom probe tomography to reveal the three-dimensional structure of the first few atomic layers of electrochemically grown iridium oxide, an efficient electrocatalyst for the oxygen evolution reaction. We unveil the formation of confined, non-stoichiometric Ir–O species during oxygen evolution. These species gradually transform to IrO2, providing improved stability but also a decrease in activity. Additionally, electrochemical growth of oxide in deuterated solutions allowed us to trace hydroxy-groups and water molecules present in the regions of the oxide layer that are favourable for the oxygen evolution and iridium dissolution reactions. Overall, we demonstrate how tomography with near-atomic resolution advances the understanding of complex relationships between surface structure, surface state and function in electrocatalysis.

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Fig. 1: Activity and stability of electrochemically formed Ir oxides and their surface electronic state.
Fig. 2: Schematic of the sample and edge-on surface oxide morphology of Ir after exposure to anodic oxidation for 69 h.
Fig. 3: APT data of as-deposited Ir film and Ir oxides formed by anodic oxidation for 4 h, 69 h and 120 h.
Fig. 4: Schematic representation of the gradual changes observed during anodic polarization of Ir under OER conditions.

References

  1. 1.

    Stamenkovic, V. R., Strmcnik, D., Lopes, P. P. & Markovic, N. M. Energy and fuels from electrochemical interfaces. Nat. Mater. 16, 57–69 (2017).

    CAS  Article  Google Scholar 

  2. 2.

    Seh, Z. W. et al. Combining theory and experiment in electrocatalysis: insights into materials design. Science 355, eaad4998 (2017).

    Article  Google Scholar 

  3. 3.

    Grimaud, A. et al. Activation of surface oxygen sites on an iridium-based model catalyst for the oxygen evolution reaction. Nat. Energy 2, 16189 (2016).

    Article  Google Scholar 

  4. 4.

    Grimaud, A. et al. Activating lattice oxygen redox reactions in metal oxides to catalyse oxygen evolution. Nat. Chem. 9, 457–465 (2017).

    CAS  Article  Google Scholar 

  5. 5.

    McCrory, C. C. et al. Benchmarking hydrogen evolving reaction and oxygen evolving reaction electrocatalysts for solar water splitting devices. J. Am. Chem. Soc. 137, 4347–4357 (2015).

    CAS  Article  Google Scholar 

  6. 6.

    McCrory, C. C., Jung, S., Peters, J. C. & Jaramillo, T. F. Benchmarking heterogeneous electrocatalysts for the oxygen evolution reaction. J. Am. Chem. Soc. 135, 16977–16987 (2013).

    CAS  Article  Google Scholar 

  7. 7.

    Reier, T., Oezaslan, M. & Strasser, P. Electrocatalytic oxygen evolution reaction (OER) on Ru, Ir, and Pt catalysts: a comparative study of nanoparticles and bulk materials. ACS Catal. 2, 1765–1772 (2012).

    CAS  Article  Google Scholar 

  8. 8.

    Beni, G., Schiavone, L. M., Shay, J.L., Dautremont-Smith, W. C. & Schneider, B. S. Electrocatalytic oxygen evolution on reactively sputtered electrochromic iridium oxide films. Nature 282, 281–283 (1979).

    CAS  Article  Google Scholar 

  9. 9.

    Cherevko, S. et al. Oxygen and hydrogen evolution reactions on Ru, RuO2, Ir, and IrO2 thin film electrodes in acidic and alkaline electrolytes: a comparative study on activity and stability. Catal. Today 262, 170–180 (2016).

    CAS  Article  Google Scholar 

  10. 10.

    Seitz, L. C. et al. A highly active and stable IrO x /SrIrO3 catalyst for the oxygen evolution reaction. Science 353, 1011–1014 (2016).

    CAS  Article  Google Scholar 

  11. 11.

    Willinger, E., Massué, C., Schlögl, R. & Willinger, M. -G. Identifying key structural features of IrO x water splitting catalysts.J. Am. Chem. Soc. 139, 12093–12101 (2017).

    CAS  Article  Google Scholar 

  12. 12.

    Spöri, C., Kwan, J. T. H., Bonakdarpour, A., Wilkinson, D. P. & Strasser, P. Stabilitätsanforderungen von Elektrokatalysatoren für die Sauerstoffentwicklung: der Weg zu einem grundlegenden Verständnis und zur Minimierung der Katalysatordegradation. Angew. Chem. Int. Ed. 129, 6088–6117 (2017).

    Article  Google Scholar 

  13. 13.

    Danilovic, N. et al. Activity–stability trends for the oxygen evolution reaction on monometallic oxides in acidic environments. J. Phys. Chem. Lett. 5, 2474–2478 (2014).

    CAS  Article  Google Scholar 

  14. 14.

    Minguzzi, A. et al. Easy accommodation of different oxidation states in iridium oxide nanoparticles with different hydration degree as water oxidation electrocatalysts. ACS Catal. 5, 5104–5115 (2015).

    CAS  Article  Google Scholar 

  15. 15.

    Reier, T. et al. Molecular insight in structure and activity of highly efficient, low-Ir Ir–Ni oxide catalysts for electrochemical water splitting (OER). J. Am. Chem. Soc. 137, 13031–13040 (2015).

    CAS  Article  Google Scholar 

  16. 16.

    Kötz, R., Neff, H. & Stucki, S. Anodic iridium oxide films: XPS‐studies of oxidation state changes and O2 evolution. J. Electrochem. Soc. 131, 72–77 (1984).

    Article  Google Scholar 

  17. 17.

    Pfeifer, V. et al. The electronic structure of iridium oxide electrodes active in water splitting. Phys. Chem. Chem. Phys. 18, 2292–2296 (2016).

    CAS  Article  Google Scholar 

  18. 18.

    Sanchez Casalongue, H. G. et al. In situ observation of surface species on iridium oxide nanoparticles during the oxygen evolution reaction. Angew. Chem. Int. Ed. 53, 7169–7172 (2014).

    CAS  Article  Google Scholar 

  19. 19.

    Reier, T., Nong, H. N., Teschner, D., Schlögl, R. & Strasser, P. Electrocatalytic oxygen evolution reaction in acidic environments—reaction mechanisms and catalysts. Adv. Energy Mater. 7, 1601275 (2017).

    Article  Google Scholar 

  20. 20.

    Wertheim, G. K. & Guggenheim, H. J. Conduction-electron screening in metallic oxides: IrO2. Phys. Rev. B 22, 4680–4683 (1980).

    CAS  Article  Google Scholar 

  21. 21.

    Chen, Y.-S. et al. Direct observation of individual hydrogen atoms at trapping sites in a ferritic steel. Science 355, 1196–1199 (2017).

    CAS  Article  Google Scholar 

  22. 22.

    Alia, S. M. et al. Activity and durability of iridium nanoparticles in the oxygen evolution reaction. J. Electrochem. Soc. 163, F3105–F3112 (2016).

    CAS  Article  Google Scholar 

  23. 23.

    Massue, C. et al. High-performance supported Ir-oxohydroxide water oxidation electrocatalysts. ChemSusChem 10, 1943–1957 (2017).

    CAS  Article  Google Scholar 

  24. 24.

    Gault, B. & Moody, M. P. & Cairney, J. M. & Ringer, S. P. Atom Probe Microscopy Vol. 160 (Springer Science & Business Media, New York, 2012).

  25. 25.

    Moody, M. P., Tang, F., Gault, B., Ringer, S. P. & Cairney, J. M. Atom probe crystallography: characterization of grain boundary orientation relationships in nanocrystalline aluminium. Ultramicroscopy 111, 493–499 (2011).

    CAS  Article  Google Scholar 

  26. 26.

    Fortes, M. A. & Ralph, B. The growth of oxide on field-Ion specimens of iridium. Proc. R. Soc. Lond. A 307, 431–448 (1968).

    CAS  Article  Google Scholar 

  27. 27.

    Li, T., Bagot, P. A. J., Marquis, E. A., Tsang, S. C. E. & Smith, G. D. W. Characterization of oxidation and reduction of Pt–Ru and Pt–Rh–Ru alloys by atom probe tomography and comparison with Pt–Rh. J. Phys. Chem. C. 116, 17633–17640 (2012).

    CAS  Article  Google Scholar 

  28. 28.

    Binninger, T. et al. Thermodynamic explanation of the universal correlation between oxygen evolution activity and corrosion of oxide catalysts. Sci. Rep. 5, 12167 (2015).

    CAS  Article  Google Scholar 

  29. 29.

    Geiger, S. et al. Activity and stability of electrochemically and thermally treated iridium for the oxygen evolution reaction. J. Electrochem. Soc. 163, F3132–F3138 (2016).

    CAS  Article  Google Scholar 

  30. 30.

    Özer, E., Spöri, C., Reier, T. & Strasser, P. Iridium(111), iridium(110), and ruthenium(0001) single crystals as model catalysts for the oxygen evolution reaction: insights into the electrochemical oxide formation and electrocatalytic activity. ChemCatChem 9, 597–603 (2016).

    Article  Google Scholar 

  31. 31.

    Chen, D., Chen, C., Baiyee, Z. M., Shao, Z. & Ciucci, F. Nonstoichiometric oxides as low-cost and highly-efficient oxygen reduction/evolution catalysts for low-temperature electrochemical devices. Chem. Rev. 115, 9869–9921 (2015).

    CAS  Article  Google Scholar 

  32. 32.

    Kasian, O., Grote, J.-P., Geiger, S., Cherevko, S. & Mayrhofer, K. J. J. The common intermediates of oxygen evolution and dissolution reactions during water electrolysis on iridium. Angew. Chem. Int. Ed. 57, 2488–2491 (2018).

    CAS  Article  Google Scholar 

  33. 33.

    Klemm, S. O. et al. Time and potential resolved dissolution analysis of rhodium using a microelectrochemical flow cell coupled to an ICP-MS. J. Elecroanal. Chem. 677–680, 50–55 (2012).

    Article  Google Scholar 

Download references

Acknowledgements

T.L. and O.K. acknowledge the Alexander von Humboldt Foundation. S.Z. and C.S thank the German Science Foundation within the Priority Programme SPP 1613 (DFG SCHE 634/12-2).

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K.J.J.M. and B.G. initiated the project. O.K. prepared Ir oxide films, performed the electrochemical and XPS measurements and carried out data analysis. T.L. prepared the APT and TEM samples, conducted the APT experiment and analysed the APT data. S.Z. carried out the TEM experiment. T.L, O.K., B.G., S.C., D.R. and K.J.J.M. wrote the paper. All authors discussed the results and their interpretation.

Corresponding authors

Correspondence to B. Gault or K. J. J. Mayrhofer.

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The authors declare no competing interests.

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Supplementary Information

Supplementary Notes 1–6, Supplementary Figures 1–8, Supplementary Table 1, Supplementary References

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Li, T., Kasian, O., Cherevko, S. et al. Atomic-scale insights into surface species of electrocatalysts in three dimensions. Nat Catal 1, 300–305 (2018). https://doi.org/10.1038/s41929-018-0043-3

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