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 42.121: Poster

Mittwoch, 25. März 2009, 17:45–20:30, P2

Growth and Characterization of Pt Nanoparticles on CeO₂ (111) Films on Cu(111) by STM — •Thorsten Staudt¹, Yaroslava Lykhach¹, Lutz Hammer², M. Alexander Schneider², and Jörg Libuda¹ — ¹Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg — ²Lehrstuhl für Festkörperphysik, Friedrich-Alexander-Universität Erlangen-Nürnberg

Precious metal nanoparticles supported on ceria films are widely used in many important applications, including three-way automotive catalysts and the catalytic oxidation of hydrocarbons. The use of ceria is motivated by its unique ability to store and release oxygen, while it is well known that metal particles supported on oxides can exhibit different chemical reactivity depending upon their size and structure.

Here we present a scanning tunnelling microscopy study on the growth of Pt nanoparticles on CeO₂(111) films. These films are grown by physical vapour deposition (PVD) of cerium on a Cu(111) substrate in O₂ at 520 K. The recipe has been adopted from the one suggested by Matolin and coworkers [1] and modified by the use of a higher oxidation temperature to form atomically flat terraces. LEED measurements reveal a well-ordered film with a (1.5x1.5) superstructure in orientation to the underlying substrate. A Volmer-Weber growth mode of ceria is identified by STM measurements. In a next step we investigate the nucleation behaviour and growth of Pt nanoparticles, prepared by PVD. Finally, the thermal stability of these particles is studied and it is found that they are transformed into flat islands upon annealing. [1] V. Matolin et al., Thin Solid Films 516 (2008) 6120-6124