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Main Title: The electronic structure of iridium and its oxides
Author(s): Pfeifer, Verena
Jones, Travis E.
Velasco Vélez, Juan J.
Massué, Cyriac
Arrigo, Rosa
Teschner, Detre
Girgsdies, Frank
Scherzer, Michael
Greiner, Mark T.
Allan, Jasmin
Hashagen, Maike
Weinberg, Gisela
Piccinin, Simone
Hävecker, Michael
Knop-Gericke, Axel
Schlögl, Robert
Type: Article
Language Code: en
Is Part Of:
Abstract: Iridium-based materials are among the most active and stable electrocatalysts for the oxygen evolution reaction. Amorphous iridium oxide structures are found to be more active than their crystalline counterparts. Herein, we combine synchrotron-based Xray photoemission and absorption spectroscopies with theoretical calculations to investigate the electronic structure of Ir metal, rutile-type IrO2, and an amorphous IrOx. Theory and experiment show that while the Ir 4f line shape of Ir metal is well described by a simple Doniach–Šunji´c function, the peculiar line shape of rutile-type IrO2 requires the addition of a shake-up satellite 1 eV above the main line. In the catalytically more active amorphous IrOx, we find that additional intensity appears in the Ir 4f spectrum at higher binding energy when compared with rutile-type IrO2 along with a pre-edge feature in the OK-edge. We identify these additional features as electronic defects in the anionic and cationic frameworks, namely formally OI􀀀 and IrIII, which may explain the increased activity of amorphous IrOx electrocatalysts. We corroborate our findings by in situ X-ray diffraction as well as in situ X-ray photoemission and absorption spectroscopies.
Issue Date: 2015
Date Available: 4-Apr-2019
DDC Class: 541 Physikalische Chemie
Subject(s): iridium oxide
conduction electron screening
Journal Title: Surface and interface analysis
Publisher: Wiley
Publisher Place: Chichester [u.a.]
Volume: 48
Issue: 5
Publisher DOI: 10.1002/sia.5895
Page Start: 261
Page End: 273
EISSN: 0142-2421
ISSN: 1096-9918
Appears in Collections:FG Technische Chemie » Publications

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