title: The electronic structure of iridium oxide electrodes active in water splitting.
abstract: Iridium oxide based electrodes are among the most promising candidates for electrocatalyzing the oxygen evolution reaction, making it imperative to understand their chemical/electronic structure. However, the complexity of iridium oxide's electronic structure makes it particularly difficult to experimentally determine the chemical state of the active surface species. To achieve an accurate understanding of the electronic structure of iridium oxide surfaces, we have combined synchrotron-based X-ray photoemission and absorption spectroscopies with ab initio calculations. Our investigation reveals a pre-edge feature in the O K-edge of highly catalytically active X-ray amorphous iridium oxides that we have identified as O 2p hole states forming in conjunction with Ir(III). These electronic defects in the near-surface region of the anionic and cationic framework are likely critical for the enhanced activity of amorphous iridium oxides relative to their crystalline counterparts.
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany. trjones@fhi-berlin.mpg.de and Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Elektronenspeicherring BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Pfeifer
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany. trjones@fhi-berlin.mpg.de.
authors.forename: T E
authors.initials: TE
authors.lastname: Jones
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany. trjones@fhi-berlin.mpg.de and Max-Planck-Institut für Chemische Energiekonversion, Stiftstr. 34-36, 45470 Mülheim a. d. Ruhr, Germany.
authors.forename: J J
authors.initials: JJ
authors.lastname: Velasco Vélez
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany. trjones@fhi-berlin.mpg.de and Max-Planck-Institut für Chemische Energiekonversion, Stiftstr. 34-36, 45470 Mülheim a. d. Ruhr, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Massué
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany. trjones@fhi-berlin.mpg.de.
authors.forename: M T
authors.initials: MT
authors.lastname: Greiner
authors.affiliation: Diamond Light Source Ltd, Harwell Science & Innovation Campus, Didcot, Oxfordshire OX 11 0DE, UK.
authors.forename: R
authors.initials: R
authors.lastname: Arrigo
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany. trjones@fhi-berlin.mpg.de.
authors.forename: D
authors.initials: D
authors.lastname: Teschner
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany. trjones@fhi-berlin.mpg.de.
authors.forename: F
authors.initials: F
authors.lastname: Girgsdies
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany. trjones@fhi-berlin.mpg.de and Max-Planck-Institut für Chemische Energiekonversion, Stiftstr. 34-36, 45470 Mülheim a. d. Ruhr, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Scherzer
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany. trjones@fhi-berlin.mpg.de.
authors.forename: J
authors.initials: J
authors.lastname: Allan
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany. trjones@fhi-berlin.mpg.de.
authors.forename: M
authors.initials: M
authors.lastname: Hashagen
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany. trjones@fhi-berlin.mpg.de.
authors.forename: G
authors.initials: G
authors.lastname: Weinberg
authors.affiliation: Instituto Officina dei Materiali (CNR-IOM), c/o SISSA - Scoula Internazionale Superiore di Studi Avanzati, Via Bonomea 267, 34136 Trieste, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Piccinin
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany. trjones@fhi-berlin.mpg.de and Max-Planck-Institut für Chemische Energiekonversion, Stiftstr. 34-36, 45470 Mülheim a. d. Ruhr, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Hävecker
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany. trjones@fhi-berlin.mpg.de.
authors.forename: A
authors.initials: A
authors.lastname: Knop-Gericke
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany. trjones@fhi-berlin.mpg.de and Max-Planck-Institut für Chemische Energiekonversion, Stiftstr. 34-36, 45470 Mülheim a. d. Ruhr, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Schlögl