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Main Title: Reactive oxygen species in iridium-based OER catalysts
Author(s): Pfeifer, Verena
Jones, Travis E.
Wrabetz, Sabine
Massué, Cyriac
Velasco Vélez, Juan J.
Arrigo, Rosa
Scherzer, Michael
Piccinin, Simone
Hävecker, Michael
Knop-Gericke, Axel
Schlögl, Robert
Type: Article
Language Code: en
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Abstract: Tremendous effort has been devoted towards elucidating the fundamental reasons for the higher activity of hydrated amorphous IrIII/IV oxyhydroxides (IrOx) in the oxygen evolution reaction (OER) in comparison with their crystalline counterpart, rutile-type IrO2, by focusing on the metal oxidation state. Here we demonstrate that, through an analogy to photosystem II, the nature of this reactive species is not solely a property of the metal but is intimately tied to the electronic structure of oxygen. We use a combination of synchrotron-based X-ray photoemission and absorption spectroscopies, ab initio calculations, and microcalorimetry to show that holes in the O 2p states in amorphous IrOx give rise to a weakly bound oxygen that is extremely susceptible to nucleophilic attack, reacting stoichiometrically with CO already at room temperature. As such, we expect this species to play the critical role of the electrophilic oxygen involved in O–O bond formation in the electrocatalytic OER on IrOx. We propose that the dynamic nature of the Ir framework in amorphous IrOx imparts the flexibility in Ir oxidation state required for the formation of this active electrophilic oxygen.
Issue Date: 2016
Date Available: 25-Apr-2017
DDC Class: 541 Physikalische Chemie
Subject(s): reactive oxygen
Journal Title: Chemical Science
Publisher: RSC
Publisher Place: Cambridge
Volume: 2016
Issue: 7
Publisher DOI: 10.1039/c6sc01860b
Page Start: 6791
Page End: 6795
ISSN: 1478-6524
Appears in Collections:FG Technische Chemie » Publications

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