title: Electrochemical Catalyst-Support Effects and Their Stabilizing Role for IrOx Nanoparticle Catalysts during the Oxygen Evolution Reaction.
abstract: Redox-active support materials can help reduce the noble-metal loading of a solid chemical catalyst while offering electronic catalyst-support interactions beneficial for catalyst durability. This is well known in heterogeneous gas-phase catalysis but much less discussed for electrocatalysis at electrified liquid-solid interfaces. Here, we demonstrate experimental evidence for electronic catalyst-support interactions in electrochemical environments and study their role and contribution to the corrosion stability of catalyst/support couples. Electrochemically oxidized Ir oxide nanoparticles, supported on high surface area carbons and oxides, were selected as model catalyst/support systems for the electrocatalytic oxygen evolution reaction (OER). First, the electronic, chemical, and structural state of the catalyst/support couple was compared using XANES, EXAFS, TEM, and depth-resolved XPS. While carbon-supported oxidized Ir particle showed exclusively the redox state (+4), the Ir/IrOx/ATO system exhibited evidence of metal/metal-oxide support interactions (MMOSI) that stabilized the metal particles on antimony-doped tin oxide (ATO) in sustained lower Ir oxidation states (Ir(3.2+)). At the same time, the growth of higher valent Ir oxide layers that compromise catalyst stability was suppressed. Then the electrochemical stability and the charge-transfer kinetics of the electrocatalysts were evaluated under constant current and constant potential conditions, where the analysis of the metal dissolution confirmed that the ATO support mitigates Ir(z+) dissolution thanks to a stronger MMOSI effect. Our findings raise the possibility that MMOSI effects in electrochemistry-largely neglected in the past-may be more important for a detailed understanding of the durability of oxide-supported nanoparticle OER catalysts than previously thought.
authors.affiliation: The Electrochemical Energy, Catalysis, and Materials Science Laboratory, Department of Chemistry, Chemical Engineering Division, Technical University Berlin , Berlin 10623, Germany.
authors.forename: Hyung-Suk
authors.initials: HS
authors.lastname: Oh
authors.affiliation: The Electrochemical Energy, Catalysis, and Materials Science Laboratory, Department of Chemistry, Chemical Engineering Division, Technical University Berlin , Berlin 10623, Germany.
authors.forename: Hong Nhan
authors.initials: HN
authors.lastname: Nong
authors.affiliation: The Electrochemical Energy, Catalysis, and Materials Science Laboratory, Department of Chemistry, Chemical Engineering Division, Technical University Berlin , Berlin 10623, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Reier
authors.affiliation: The Electrochemical Energy, Catalysis, and Materials Science Laboratory, Department of Chemistry, Chemical Engineering Division, Technical University Berlin , Berlin 10623, Germany.
authors.forename: Arno
authors.initials: A
authors.lastname: Bergmann
authors.affiliation: The Electrochemical Energy, Catalysis, and Materials Science Laboratory, Department of Chemistry, Chemical Engineering Division, Technical University Berlin , Berlin 10623, Germany.
authors.forename: Manuel
authors.initials: M
authors.lastname: Gliech
authors.affiliation: The Electrochemical Energy, Catalysis, and Materials Science Laboratory, Department of Chemistry, Chemical Engineering Division, Technical University Berlin , Berlin 10623, Germany.
authors.forename: Jorge
authors.initials: J
authors.lastname: Ferreira de Araújo
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft , Abteilung Anorganische Chemie, Berlin 14195, Germany.
authors.forename: Elena
authors.initials: E
authors.lastname: Willinger
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft , Abteilung Anorganische Chemie, Berlin 14195, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Schlögl
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft , Abteilung Anorganische Chemie, Berlin 14195, Germany.
authors.forename: Detre
authors.initials: D
authors.lastname: Teschner
authors.affiliation: The Electrochemical Energy, Catalysis, and Materials Science Laboratory, Department of Chemistry, Chemical Engineering Division, Technical University Berlin , Berlin 10623, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Strasser