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Microkinetic Barriers of the Oxygen Evolution on the Oxides of Iridium, Ruthenium and their Binary Mixtures

Geppert, Janis ORCID iD icon 1; Röse, Philipp ORCID iD icon 1; Pauer, Swantje ORCID iD icon 1; Krewer, Ulrike ORCID iD icon 1
1 Institut für Angewandte Materialien – Keramische Werkstoffe und Technologien (IAM-KWT1), Karlsruher Institut für Technologie (KIT)

Abstract:

The performance of electrocatalytic water splitting in polymer electrolyte membrane electrolysis is substantially determined by the microkinetic processes of the oxygen evolution reaction (OER). Even highly active catalysts such as the nanoparticulated transition metal oxides IrO$_{2}$, RuO$_{2}$ and their mixtures, Ir$_{x}$Ru$_{1-x}$O$_{2}$, exhibit overpotentials up to several hundreds of millivolts. The surface of the oxide mixtures Ir$_{x}$Ru$_{1-x}$O$_{2}$ is found to consist of actives sites of both Ir and Ru on which the OER mechanism is processed independently and at different overpotentials. By applying microkinetic modelling and parameterization via cyclic voltammograms we show that there is a correlation between performance and the relative Ir content, that can be explained by two different deprotonation steps. These are in particular the formation of the adsorbate species *OOH on rutile RuO$_{2}$ and *OO on IrO$_{2}$. The respective free reaction energies are quantified to 1.44 eV and 1.58 eV, which are the highest values of the process and thus determining the overpotential. The additional finding of adsorbed oxygen *O covering >40 % of the active sites during the OER suggests that subsequent water adsorption is the major performance limiting step. ... mehr


Verlagsausgabe §
DOI: 10.5445/IR/1000151830
Veröffentlicht am 04.11.2022
Originalveröffentlichung
DOI: 10.1002/celc.202200481
Scopus
Zitationen: 6
Web of Science
Zitationen: 5
Dimensions
Zitationen: 6
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Angewandte Materialien – Elektrochemische Technologien (IAM-ET1)
Institut für Angewandte Materialien – Keramische Werkstoffe und Technologien (IAM-KWT1)
Publikationstyp Zeitschriftenaufsatz
Publikationsdatum 26.10.2022
Sprache Englisch
Identifikator ISSN: 2196-0216
KITopen-ID: 1000151830
HGF-Programm 38.03.02 (POF IV, LK 01) Power-based Fuels and Chemicals
Erschienen in ChemElectroChem
Verlag John Wiley and Sons
Band 9
Heft 20
Seiten Art.Nr. e202200481
Vorab online veröffentlicht am 29.09.2022
Nachgewiesen in Web of Science
Scopus
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