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The stability number as a metric for electrocatalyst stability benchmarking

Abstract

Reducing the noble metal loading and increasing the specific activity of the oxygen evolution catalysts are omnipresent challenges in proton-exchange-membrane water electrolysis, which have recently been tackled by utilizing mixed oxides of noble and non-noble elements. However, proper verification of the stability of these materials is still pending. Here we introduce a metric to explore the dissolution processes of various iridium-based oxides, defined as the ratio between the amounts of evolved oxygen and dissolved iridium. The so-called stability number is independent of loading, surface area or involved active sites and provides a reasonable comparison of diverse materials with respect to stability. The case study on iridium-based perovskites shows that leaching of the non-noble elements in mixed oxides leads to the formation of highly active amorphous iridium oxide, the instability of which is explained by the generation of short-lived vacancies that favour dissolution. These insights are meant to guide further research, which should be devoted to increasing the utilization of highly durable pure crystalline iridium oxide and finding solutions to stabilize amorphous iridium oxides.

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Fig. 1: Crystal structure of the investigated materials.
Fig. 2: XPS results for pristine Ba2PrIrO6, amorphous IrOx and crystalline IrO2.
Fig. 3: Investigation of iridium dissolution during OER.
Fig. 4: Comparison of the investigated materials in terms of activity.
Fig. 5: Online observation of lattice oxygen evolution.
Fig. 6: Sketch of the simplified OER reaction mechanism with dissolution pathways.
Fig. 7: Investigation of S–number and lifetime depending on the current load.

References

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

    Article  CAS  PubMed  Google Scholar 

  2. Diaz-Morales, O. et al. Iridium-based double perovskites for efficient water oxidation in acid media. Nat. Commun. 7, 12363 (2016).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  3. 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).

    Article  CAS  PubMed  Google Scholar 

  4. Lettenmeier, P. et al. Nanosized IrOx–Ir catalyst with relevant activity for anodes of proton exchange membrane electrolysis produced by a cost-effective procedure. Angew. Chem. Int Ed. 55, 742–746 (2016).

    Article  CAS  Google Scholar 

  5. Sun, W., Song, Y., Gong, X.-Q., Cao, L.-m. & Yang, J. An efficiently tuned d-orbital occupation of IrO2 by doping with Cu for enhancing the oxygen evolution reaction activity. Chem. Sci. 6, 4993–4999 (2015).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  6. Sun, W. et al. OER activity manipulated by IrO6 coordination geometry: an insight from pyrochlore iridates. Sci. Rep. 6, 38429 (2016).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  7. Nong, H. N. et al. Oxide-supported IrNiOx core–shell particles as efficient, cost-effective, and stable catalysts for electrochemical water splitting. Angew. Chem. Int Ed. 54, 2975–2979 (2015).

    Article  CAS  Google Scholar 

  8. Sun, W., Song, Y., Gong, X. Q., Cao, L. M. & Yang, J. Hollandite structure Kx≈0.25IrO2 catalyst with highly efficient oxygen evolution reaction. ACS Appl. Mater. Interfaces 8, 820–826 (2016).

    Article  CAS  PubMed  Google Scholar 

  9. Pourbaix, M. Atlas of Electrochemical Equilibria in Aqueous Solutions (National Association of Corrosion Engineers, 1974).

  10. 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).

    Article  CAS  Google Scholar 

  11. Abbott, D. F. et al. Iridium oxide for the oxygen evolution reaction: correlation between particle size, morphology, and the surface hydroxo layer from operando XAS. Chem. Mater. 28, 6591–6604 (2016).

    Article  CAS  Google Scholar 

  12. 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).

    Article  CAS  Google Scholar 

  13. Bockris, J. O. M. & Otagawa, T. The electrocatalysis of oxygen evolution on perovskites. J. Electrochem. Soc. 131, 290–302 (1984).

    Article  CAS  Google Scholar 

  14. Suntivich, J., May, K. J., Gasteiger, H. A., Goodenough, J. B. & Shao-Horn, Y. A perovskite oxide optimized for oxygen evolution catalysis from molecular orbital principles. Science 334, 1383–1385 (2011).

    Article  CAS  PubMed  Google Scholar 

  15. Zhu, L., Ran, R., Tadé, M., Wang, W. & Shao, Z. Perovskite materials in energy storage and conversion. Asia-Pac. J. Chem. Eng. 11, 338–369 (2016).

    Article  CAS  Google Scholar 

  16. Petrie, J. R., Jeen, H., Barron, S. C., Meyer, T. L. & Lee, H. N. Enhancing perovskite electrocatalysis through strain tuning of the oxygen deficiency. J. Am. Chem. Soc. 138, 7252–7255 (2016).

    Article  CAS  PubMed  Google Scholar 

  17. May, K. J. et al. Influence of oxygen evolution during water oxidation on the surface of perovskite oxide catalysts. J. Phys. Chem. Lett. 3, 3264–3270 (2012).

    Article  CAS  Google Scholar 

  18. Risch, M. et al. Structural changes of cobalt-based perovskites upon water oxidation investigated by EXAFS. J. Phys. Chem. C 117, 8628–8635 (2013).

    Article  CAS  Google Scholar 

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

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  20. 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  CAS  Google Scholar 

  21. Sen, F. G. et al. Towards accurate prediction of catalytic activity in IrO2 nanoclusters via first principles-based variable charge force field. J. Mater. Chem. A 3, 18970–18982 (2015).

    Article  CAS  Google Scholar 

  22. Gottesfeld, S. & Srinivasan, S. Electrochemical and optical studies of thick oxide layers on iridium and their electrocatalytic activities for the oxygen evolution reaction. J. Electroanal. Chem. Interfacial Electrochem. 86, 89–104 (1978).

    Article  CAS  Google Scholar 

  23. Reier, T., Weidinger, I., Hildebrandt, P., Kraehnert, R. & Strasser, P. Electrocatalytic oxygen evolution reaction on iridium oxide model film catalysts: influence of oxide type and catalyst substrate interactions. ECS Trans. 58, 39–51 (2013).

    Article  CAS  Google Scholar 

  24. Pfeifer, V. et al. The electronic structure of iridium and its oxides. Surf. Interface Anal. 48, 261–273 (2016).

    Article  CAS  Google Scholar 

  25. 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).

    Article  CAS  Google Scholar 

  26. Fu, W. T. & Ijdo, D. J. W. On the space group of the double perovskite Ba2PrIrO6. J. Solid State Chem. 178, 1312–1316 (2005).

    Article  CAS  Google Scholar 

  27. Strasser, P. Free electrons to molecular bonds and back: closing the energetic oxygen reduction (ORR)–oxygen evolution (OER) cycle using core–shell nanoelectrocatalysts. Acc. Chem. Res. 49, 2658–2668 (2016).

    Article  CAS  PubMed  Google Scholar 

  28. 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).

    Article  CAS  Google Scholar 

  29. Jovanovič, P. et al. Electrochemical dissolution of iridium and iridium oxide particles in acidic media: transmission electron microscopy, electrochemical flow cell coupled to inductively coupled plasma mass spectrometry, and X-ray absorption spectroscopy study. J. Am. Chem. Soc. 139, 12837–12846 (2017).

    Article  CAS  PubMed  Google Scholar 

  30. Trasatti, S. & Petrii, O. A. Real surface area measurements in electrochemistry. J. Electroanal. Chem. 327, 353–376 (1992).

    Article  CAS  Google Scholar 

  31. 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).

    Article  CAS  Google Scholar 

  32. Minguzzi, A. et al. Observing the oxidation state turnover in heterogeneous iridium-based water oxidation catalysts. Chem. Sci. 5, 3591 (2014).

    Article  CAS  Google Scholar 

  33. Pickup, P. G. & Birss, V. I. A model for anodic hydrous oxide growth at iridium. J. Electroanal. Chem. Interfacial Electrochem. 220, 83–100 (1987).

    Article  CAS  Google Scholar 

  34. Burke, L. D. & Whelan, D. P. A voltammetric investigation of the charge storage reactions of hydrous iridium oxide layers. J. Electroanal. Chem. Interfacial Electrochem. 162, 121–141 (1984).

    Article  CAS  Google Scholar 

  35. Fabbri, E., Habereder, A., Waltar, K., Kötz, R. & Schmidt, T. J. Developments and perspectives of oxide-based catalysts for the oxygen evolution reaction. Catal. Sci. Technol. 4, 3800–3821 (2014).

    Article  CAS  Google Scholar 

  36. 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 (2016).

    Article  CAS  Google Scholar 

  37. Rong, X., Parolin, J. & Kolpak, A. M. A fundamental relationship between reaction mechanism and stability in metal oxide catalysts for oxygen evolution. ACS Catal. 6, 1153–1158 (2016).

    Article  CAS  Google Scholar 

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

  39. Pfeifer, V. et al. Reactive oxygen species in iridium-based OER catalysts. Chem. Sci. 7, 6791–6795 (2016).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  40. Pfeifer, V. et al. In situ observation of reactive oxygen species forming on oxygen-evolving iridium surfaces. Chem. Sci. 8, 2143–2149 (2017).

    Article  CAS  PubMed  Google Scholar 

  41. Willinger, E., Massue, C., Schlogl, R. & Willinger, M. G. Identifying key structural features of IrOx water splitting catalysts. J. Am. Chem. Soc. 139, 12093–12101 (2017).

    Article  CAS  PubMed  Google Scholar 

  42. Fierro, S., Nagel, T., Baltruschat, H. & Comninellis, C. Investigation of the oxygen evolution reaction on Ti/IrO2 electrodes using isotope labelling and on-line mass spectrometry. Electrochem. Commun. 9, 1969–1974 (2007).

    Article  CAS  Google Scholar 

  43. Rossmeisl, J., Qu, Z. W., Zhu, H., Kroes, G. J. & Nørskov, J. K. Electrolysis of water on oxide surfaces. J. Electroanal. Chem. 607, 83–89 (2007).

    Article  CAS  Google Scholar 

  44. Ooka, H., Takashima, T., Yamaguchi, A., Hayashi, T. & Nakamura, R. Element strategy of oxygen evolution electrocatalysis based on in situ spectroelectrochemistry. Chem. Commun. 53, 7149–7161 (2017).

    Article  CAS  Google Scholar 

  45. Bockris, J. O. M. Kinetics of activation controlled consecutive electrochemical reactions: anodic evolution of oxygen. J. Chem. Phys. 24, 817 (1956).

    Article  CAS  Google Scholar 

  46. Cherevko, S. et al. Dissolution of noble metals during oxygen evolution in acidic media. ChemCatChem 6, 2219–2223 (2014).

    Article  CAS  Google Scholar 

  47. Mefford, J. T. et al. Water electrolysis on La1–xSrxCoO3–δ perovskite electrocatalysts. Nat. Commun. 7, 11053 (2016).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  48. Cherevko, S., Geiger, S., Kasian, O., Mingers, A. & Mayrhofer, K. J. J. Oxygen evolution activity and stability of iridium in acidic media. Part 2. – Electrochemically grown hydrous iridium oxide. J. Electroanal. Chem. 774, 102–110 (2016).

    Article  CAS  Google Scholar 

  49. 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 

  50. 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).

    Article  CAS  Google Scholar 

  51. Kim, Y.-T. et al. Balancing activity, stability and conductivity of nanoporous core–shell iridium/iridium oxide oxygen evolution catalysts. Nat. Commun. 8, 1449 (2017).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  52. Oh, H.-S., Nong, H. N. & Strasser, P. Preparation of mesoporous Sb-, F-, and In-doped SnO2 bulk powder with high surface area for use as catalyst supports in electrolytic cells. Adv. Funct. Mater. 25, 1074–1081 (2015).

    Article  CAS  Google Scholar 

  53. Li, Z. Z., Schneegans, O. & Fruchter, L. Synthesis of perovskite SrIrO3 thin films by sputtering technique. Preprint at http://arxiv.org/abs/1610.03722 (2016).

  54. Klemm, S. O., Topalov, A. A., Laska, C. A. & Mayrhofer, K. J. J. Coupling of a high throughput microelectrochemical cell with online multielemental trace analysis by ICP-MS. Electrochem. Commun. 13, 1533–1535 (2011).

    Article  CAS  Google Scholar 

  55. Grote, J. P., Zeradjanin, A. R., Cherevko, S. & Mayrhofer, K. J. Coupling of a scanning flow cell with online electrochemical mass spectrometry for screening of reaction selectivity. Rev. Sci. Instrum. 85, 104101 (2014).

    Article  CAS  PubMed  Google Scholar 

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Acknowledgements

The authors acknowledge funding by the German Federal Ministry of Education and Research (BMBF) within the Kopernikus Project P2X and a further project (Kz: 033RC1101A). S.G. acknowledges financial support from BASF. O.K. acknowledges financial support from the Alexander von Humboldt Foundation. E.P. and T.O. acknowledge financial support from the IMPRS-SurMat doctoral program. K.J.J.M. acknowledges financial support from the DFG under project number MA4819/4-1. L.F. and Z.L. acknowledge support from the Agence Nationale de la Recherche grant SOCRATE ANR-15-CE30-0009-01. Additional thanks go to K. Hengge and T. Gänsler for carrying out the TEM and SAED measurements.

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Contributions

S.G. composed the manuscript and performed electrochemical dissolution measurements. O.K. carried out OLEMS measurements, IrO2-sputtering and XPS. A.M.M. carried out ICP-MS analysis. W.T.F. and O.D.-M. synthesized double-perovskite powders. Z.L. and L.F. synthesized SrIrO3 films. T.O. and A.L. contributed by allocating sputtered iridium dots. S.G., O.K., M.L., E.P., M.T.M.K., K.J.J.M. and S.C. contributed through scientific discussions and revision of the manuscript.

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Correspondence to Simon Geiger or Serhiy Cherevko.

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Supplementary Notes 1–6; Supplementary Methods; Supplementary Figures 1–14; Supplementary Table 1; Supplementary References

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Geiger, S., Kasian, O., Ledendecker, M. et al. The stability number as a metric for electrocatalyst stability benchmarking. Nat Catal 1, 508–515 (2018). https://doi.org/10.1038/s41929-018-0085-6

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