Dresden 2006 – wissenschaftliches Programm
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O: Oberflächenphysik
O 14: Poster session I (Adsorption, Epitaxy and growth, Phase transitions, Surface reactions, Organic films, Electronic structure, Methods) (sponsored by Omicron Nanotechnology GmbH)
O 14.38: Poster
Montag, 27. März 2006, 18:00–21:00, P2
Oxidation of magnesia-supported Pd-clusters leads to the ultimate limit of epitaxy with a catalytic function — •Bernd Huber1, Pekka Koskinen2, Hannu Häkkinen3, and Michael Moseler1,3 — 1Freiburg Materials Research Center, University of Freiburg, D-79104 Freiburg, Germany — 2Fraunhofer Institute for Mechanics of Materials, Wöhlerstr. 11, D-79108, Germany — 3Department of Physics, NanoScience Center, FIN-40014 University of Jyväskylä, Finland
Oxide-supported transition metal clusters and nanoparticles have attracted significant attention owing to their important role as components of model-catalysts, sensors and solar-cells. For small clusters, functionality and structure are closely interrelated. However, knowledge of the structure of the bare cluster is insufficient since the interaction with the chemical environment might cause drastic structural changes. Here we show by ab initio simulations based on the density functional theory that the reaction with molecular oxygen transforms small, non-crystalline, magnesia-supported Pd-clusters to crystalline PdO nano-oxide clusters that are in epitaxy with the underlying support. Restructuring of the Pd backbone is controlled by the electrostatic interaction with magnesia leading to a strong reduction of the O2 dissociation barrier. The supported PdO clusters are likely to serve as Mars-van Krevelen oxygen reservoirs in catalytic oxidation reactions as observed previously for PdO overlayers and demonstrated here for the oxidation of CO molecules
[1] B. Huber, P. Koskinen, H. Häkkinen and M. Moseler, NMat (in press).