title: Bridging the gap between nanoparticles and single crystal surfaces.
abstract: Using density functional theory calculations and the extended ab initio atomistic thermodynamics approach, we studied the adsorption of oxygen on the different surface faces, which are involved in the faceting of Ir(210). Constructing the (p,T)-surface phase diagrams of the corresponding surfaces in contact with an oxygen atmosphere, we find that at high temperatures the planar surfaces are stable, while lowering the temperature stabilizes those nano-facets found experimentally. Afterwards, we constructed the (a,T,deltaphi)-phase diagram for Ir(210) in contact with an aqueous electrolyte and found that the same nano-facets should be stable under electrochemical conditions. Motivated by this prediction from theory, experiments were performed using cyclic voltammetry and in-situ scanning tunneling microscopy. The presence of nanofacets for Ir(210) gives rise to a characteristic current-peak in the hydrogen adsorption region for sulfuric acid solution. Furthermore, first results on the electrocatalytic behavior of nano-faceted Ir(210) are presented.
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany.
authors.forename: Payam
authors.initials: P
authors.lastname: Kaghazchi
authors.forename: Felice C
authors.initials: FC
authors.lastname: Simeone
authors.forename: Khaled A
authors.initials: KA
authors.lastname: Soliman
authors.forename: Ludwig A
authors.initials: LA
authors.lastname: Kibler
authors.forename: Timo
authors.initials: T
authors.lastname: Jacob
mesh_terms: D002384:Catalysis; D003198:Computer Simulation; D003460:Crystallization / Q000379:methods*; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods; D004566:Electrodes; D004579:Electron Transport; D007495:Iridium / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D053758:Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D010984:Platinum / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D007495:Iridium; D010984:Platinum