title: Molecular Insight in Structure and Activity of Highly Efficient, Low-Ir Ir-Ni Oxide Catalysts for Electrochemical Water Splitting (OER).
abstract: Mixed bimetallic oxides offer great opportunities for a systematic tuning of electrocatalytic activity and stability. Here, we demonstrate the power of this strategy using well-defined thermally prepared Ir-Ni mixed oxide thin film catalysts for the electrochemical oxygen evolution reaction (OER) under highly corrosive conditions such as in acidic proton exchange membrane (PEM) electrolyzers and photoelectrochemical cells (PEC). Variation of the Ir to Ni ratio resulted in a volcano type OER activity curve with an unprecedented 20-fold improvement in Ir mass-based activity over pure Ir oxide. In situ spectroscopic probing of metal dissolution indicated that, against common views, activity and stability are not directly anticorrelated. To uncover activity and stability controlling parameters, the Ir-Ni mixed thin oxide film catalysts were characterized by a wide array of spectroscopic, microscopic, scattering, and electrochemical techniques in conjunction with DFT theoretical computations. By means of an intuitive model for the formation of the catalytically active state of the bimetallic Ir-Ni oxide surface, we identify the coverage of reactive surface hydroxyl groups as a suitable descriptor for the OER activity and relate it to controllable synthetic parameters. Overall, our study highlights a novel, highly active oxygen evolution catalyst; moreover, it provides novel important insights into the structure and performance of bimetallic oxide OER electrocatalysts in corrosive acidic environments.
authors.affiliation: Department of Chemistry, Chemical and Materials Engineering Division, The Electrochemical Energy, Catalysis and Materials Science Laboratory, Technische Universität Berlin , Straße des 17. Juni 124, 10623 Berlin, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Reier
authors.affiliation: Department of Chemistry, Chemical and Materials Engineering Division, The Electrochemical Energy, Catalysis and Materials Science Laboratory, Technische Universität Berlin , Straße des 17. Juni 124, 10623 Berlin, Germany.
authors.forename: Zarina
authors.initials: Z
authors.lastname: Pawolek
authors.affiliation: Department of Interface Chemistry and Surface Engineering, Max-Planck-Institut für Eisenforschung GmbH , Max-Planck-Straße 1, 40237 Düsseldorf, Germany.
authors.forename: Serhiy
authors.initials: S
authors.lastname: Cherevko
authors.affiliation: Institute for Applied Materials and Karlsruhe Nano Micro Facility, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Bruns
authors.affiliation: Department of Inorganic Chemistry, Fritz-Haber-Institute of the Max-Planck-Society , Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: Travis
authors.initials: T
authors.lastname: Jones
authors.affiliation: Department of Inorganic Chemistry, Fritz-Haber-Institute of the Max-Planck-Society , Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: Detre
authors.initials: D
authors.lastname: Teschner
authors.affiliation: Zentraleinrichtung Elektronenmikroskopie, Technische Universität Berlin , D-10623 Berlin, Germany.
authors.forename: Sören
authors.initials: S
authors.lastname: Selve
authors.affiliation: Department of Chemistry, Chemical and Materials Engineering Division, The Electrochemical Energy, Catalysis and Materials Science Laboratory, Technische Universität Berlin , Straße des 17. Juni 124, 10623 Berlin, Germany.
authors.forename: Arno
authors.initials: A
authors.lastname: Bergmann
authors.affiliation: Department of Chemistry, Chemical and Materials Engineering Division, The Electrochemical Energy, Catalysis and Materials Science Laboratory, Technische Universität Berlin , Straße des 17. Juni 124, 10623 Berlin, Germany.
authors.forename: Hong Nhan
authors.initials: HN
authors.lastname: Nong
authors.affiliation: Department of Inorganic Chemistry, Fritz-Haber-Institute of the Max-Planck-Society , Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Schlögl
authors.affiliation: Department of Interface Chemistry and Surface Engineering, Max-Planck-Institut für Eisenforschung GmbH , Max-Planck-Straße 1, 40237 Düsseldorf, Germany.
authors.forename: Karl J J
authors.initials: KJ
authors.lastname: Mayrhofer
authors.affiliation: Department of Chemistry, Chemical and Materials Engineering Division, The Electrochemical Energy, Catalysis and Materials Science Laboratory, Technische Universität Berlin , Straße des 17. Juni 124, 10623 Berlin, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Strasser