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          Institute: MPI für bioanorganische Chemie     Collection: MPI für bioanorganische Chemie     Display Documents

ID: 720463.0, MPI für bioanorganische Chemie / MPI für bioanorganische Chemie
The electronic structure of iridium and its oxides
Authors:Pfeifer, Verena; Jones, Travis E.; Velasco-Vélez, Juan Jesus; 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
Date of Publication (YYYY-MM-DD):2016
Title of Journal:Surface and Interface Analysis
Journal Abbrev.:Surf.Interface Anal.
Issue / Number:5
Start Page:261
End Page:273
Review Status:Internal review
Audience:Experts Only
Abstract / Description: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 X-ray 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-Sunji function, the peculiar line shape of rutile-type IrO2 requires the addition of a shake-up satellite 1eV 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 O K-edge. We identify these additional features as electronic defects in the anionic and cationic frameworks, namely, formally OI- and Ir-III, 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. Copyright (c) 2015 John Wiley & Sons, Ltd.
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für bioanorganische Chemie
Identifiers:ISI:000373935900006 [ID No:1]
ISSN:0142-2421 [ID No:2]
DOI:10.1002/sia.5895 [ID No:3]
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