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Identifying the oxygen evolution mechanism by microkinetic modelling of cyclic voltammograms

Geppert, Janis ORCID iD icon; Kubannek, Fabian ; Röse, Philipp ORCID iD icon; Krewer, Ulrike ORCID iD icon

Abstract:

Electrocatalytic water splitting is currently one of the most promising reactions to produce “green” hydrogen in a decarbonized energy system. Its bottleneck reaction, the oxygen evolution reaction (OER), is catalysed by hydrous iridium, a stable and active catalyst material. Improving the OER requires a better and especially quantitative understanding of the reaction mechanism as well as its kinetics. In this work, we present an experimentally validated microkinetic model that allows to quantify the mechanistic pathways, emerging surface species prior and during the OER, the reaction rates for the single steps and essential thermodynamic properties. Therefore, two mechanisms based on density functional theory and experimental findings are evaluated on which only simulation results of the theory-based one are found to be in full accordance with cyclic voltammograms even at different potential rates and, thus, able to describe the catalytic system. The simulation implies that oxygen is evolving mostly via a fast single site pathway (∗OO → ∗ + O2 ) with an effective reaction rate, which is several orders of magnitude faster compared to the slow dual site (2∗ O → 2∗ + O2) pathway rate. ... mehr


Verlagsausgabe §
DOI: 10.5445/IR/1000131384
Veröffentlicht am 21.12.2022
Originalveröffentlichung
DOI: 10.1016/j.electacta.2021.137902
Scopus
Zitationen: 15
Web of Science
Zitationen: 14
Dimensions
Zitationen: 16
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 01.06.2021
Sprache Englisch
Identifikator ISSN: 0013-4686, 1873-3859
KITopen-ID: 1000131384
Erschienen in Electrochimica Acta
Verlag Elsevier
Band 380
Seiten Art.-Nr.: 137902
Vorab online veröffentlicht am 03.02.2021
Nachgewiesen in Web of Science
Scopus
Dimensions
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