Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 42: Poster Session II (Nanostructures at surfaces: arrays; Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: Other; Nanostructures at surfaces: Wires, tubes; Metal substrates: Adsorption of O and/or H; Metal substrates: Clean surfaces; Metal substrates: Adsorption of organic/bio moledules; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsorption of inorganic molecules; Metal substrates: Epitaxy and growth; Heterogeneous catalysis; Surface chemical reactions; Ab-initio approaches to excitations in condensed matter; Organic, polymeric, biomolecular films– also with adsorbates; Particles and clusters)
O 42.85: Poster
Mittwoch, 25. März 2009, 17:45–20:30, P2
Nanoporous Gold: XPS and In-situ XPS Investigation — •Karifala Dumbuya1, Arne Wittstock2,3, Volkmar Zielasek2, Jürgen Biener3, Alex Hamza3, Marcus Bäumer2, Michael Gottfried1, and Hans-Peter Steinrück1 — 1Universität Erlangen-Nürnberg, Lehrstuhl für Physikalische Chemie II, Egerlandstr. 3, 91058 Erlangen, Germany — 2Institute for Applied and Physical Chemistry, University of Bremen, Leobener Strasse NW2, 28359 Bremen, Germany — 3Nanoscale Synthesis and Characterization Laboratory, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550, United States of America
Recent reports [1] have revealed that monolithic nanoporous gold (npAu) exhibits remarkably high catalytic activity for CO oxidation. This observation is surprising because the traditional catalyst is of the oxide-supported type. The specific particle-support interactions, which apparently play important roles in the standard Au catalyst, are absent for the nanoporous Au. If this is the case, then why does it display such high activity? The answer is most likely related to traces of residual Ag in the npAu. To highlight the role played by each metal in the catalytic process,we have investigated npAu with respect to changes in the chemical and electronic states of both metals with and without CO and O2 using in-situ XPS (1 mbar) and XPS, respectively. Our results confirm previous XPS results in that segregation of Ag occurs in the surface region. HP-XPS data suggests that this residual Ag plays a significant role in activating molecular oxygen. [1] V. Zielasek et al., Angew. Chem. Int. Ed. 2006, 45, 8241-8244.