title: Edge reactivity and water-assisted dissociation on cobalt oxide nanoislands.
abstract: Transition metal oxides show great promise as Earth-abundant catalysts for the oxygen evolution reaction in electrochemical water splitting. However, progress in the development of highly active oxide nanostructures is hampered by a lack of knowledge of the location and nature of the active sites. Here we show, through atom-resolved scanning tunnelling microscopy, X-ray spectroscopy and computational modelling, how hydroxyls form from water dissociation at under coordinated cobalt edge sites of cobalt oxide nanoislands. Surprisingly, we find that an additional water molecule acts to promote all the elementary steps of the dissociation process and subsequent hydrogen migration, revealing the important assisting role of a water molecule in its own dissociation process on a metal oxide. Inspired by the experimental findings, we theoretically model the oxygen evolution reaction activity of cobalt oxide nanoislands and show that the nanoparticle metal edges also display favourable adsorption energetics for water oxidation under electrochemical conditions.
authors.affiliation: Interdisciplinary Nanoscience Center, Aarhus University, DK-8000 Aarhus C, Denmark.
authors.forename: J
authors.initials: J
authors.lastname: Fester
authors.affiliation: Chemical Engineering and SLAC National Accelerator Laboratory, Stanford University, Stanford, California 94025, USA.|School of Chemistry, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: M
authors.initials: M
authors.lastname: García-Melchor
authors.affiliation: School of Chemistry, University of Manchester, Manchester M13 9PL, UK.
authors.forename: A S
authors.initials: AS
authors.lastname: Walton
authors.affiliation: Chemical Engineering and SLAC National Accelerator Laboratory, Stanford University, Stanford, California 94025, USA.
authors.forename: M
authors.identifier: 0000-0003-1168-8616
authors.initials: M
authors.lastname: Bajdich
authors.affiliation: Department of Physics and Astronomy, Institute for Storage Ring Facilities, Aarhus, DK-8000 Aarhus C, Denmark.
authors.forename: Z
authors.initials: Z
authors.lastname: Li
authors.affiliation: Interdisciplinary Nanoscience Center, Aarhus University, DK-8000 Aarhus C, Denmark.
authors.forename: L
authors.identifier: 0000-0002-3032-1476
authors.initials: L
authors.lastname: Lammich
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 220 South 33rd Street 311A Towne Building Philadelphia Pennsylvania, 19104, USA.
authors.forename: A
authors.initials: A
authors.lastname: Vojvodic
authors.affiliation: Interdisciplinary Nanoscience Center, Aarhus University, DK-8000 Aarhus C, Denmark.
authors.forename: J V
authors.initials: JV
authors.lastname: Lauritsen