Degradation of iridium oxides via oxygen evolution from the lattice: Correlating atomic scale structure with reaction mechanisms

Kasian O, Geiger S, Li T, Grote JP, Schweinar K, Zhang S, Scheu C, Raabe D, Cherevko S, Gault B, Mayrhofer K (2019)

Publication Type: Journal article

Publication year: 2019

Journal

Energy and Environmental Science Royal Society of Chemistry

Book Volume: 12

Pages Range: 3548-3555

Journal Issue: 12

DOI: 10.1039/c9ee01872g

Abstract

Understanding the fundamentals of iridium degradation during the oxygen evolution reaction is of importance for the development of efficient and durable water electrolysis systems. The degradation mechanism is complex and it is under intense discussion whether the oxygen molecule can be directly released from the oxide lattice. Here, we define the extent of lattice oxygen participation in the oxygen evolution and associated degradation of rutile and hydrous iridium oxide catalysts, and correlate this mechanism with the atomic-scale structures of the catalytic surfaces. We combine isotope labelling with atom probe tomography, online electrochemical and inductively coupled plasma mass spectrometry. Our data reveal that, unlike rutile IrO2, Ir hydrous oxide contains -IrIIIOOH species which directly contribute to the oxygen evolution from the lattice. This oxygen evolution mechanism results in faster degradation and dissolution of Ir. In addition, near surface bulk regions of hydrous oxide are involved in the oxygen catalysis and dissolution, while only the topmost atomic layers of rutile IrO2 participate in both reactions. Overall our data provide a contribution to the fundamental understanding of the exceptional stability of Ir-oxides towards the oxygen evolution reaction. The proposed approach to a quantitative assessment of the degree of lattice oxygen participation in the oxygen evolution reaction can be further applied to other oxide catalyst systems.

Authors with CRIS profile

Karl Mayrhofer Lehrstuhl für Elektrokatalyse (HIERN)

Involved external institutions

Max-Planck-Institut für Eisenforschung GmbH (MPIE) / Max Planck Institute for Iron Research DE Germany (DE) Forschungszentrum Jülich / Research Centre Jülich (FZJ) DE Germany (DE) Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) DE Germany (DE)

How to cite

APA:

Kasian, O., Geiger, S., Li, T., Grote, J.-P., Schweinar, K., Zhang, S.,... Mayrhofer, K. (2019). Degradation of iridium oxides via oxygen evolution from the lattice: Correlating atomic scale structure with reaction mechanisms. Energy and Environmental Science, 12(12), 3548-3555. https://doi.org/10.1039/c9ee01872g

MLA:

Kasian, Olga, et al. "Degradation of iridium oxides via oxygen evolution from the lattice: Correlating atomic scale structure with reaction mechanisms." Energy and Environmental Science 12.12 (2019): 3548-3555.

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