Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 23: Nanostructures at surfaces: Dots, particles, clusters

O 23.5: Vortrag

Dienstag, 23. März 2010, 11:30–11:45, H33

Oxygen-induced shape changes of Pt nanoparticles on MgO(100) — •Uta Hejral, Andreas Stierle, Alina Vlad, Mélissa Delheusy, and Helmut Dosch — Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart, Germany

Platinum nanoparticles on oxide carrier materials are used in heterogenous catalysis and are applied successfully in reactions like the oxidation of hydrocarbons or carbon monoxide [1]. In order to achieve better catalyst efficiency, lifetime and selectivity it is important to comprehend catalytic processes on an atomic basis. Thus, the interplay between particle shape, adsorbed oxygen, bulk oxides and catalytic activity needs to be understood. Therefore Pt nanoparticles have been grown epitaxially on MgO(100) substrates under controlled conditions. It has previously been reported that Rh nanoparticles undergo reversible shape changes induced by surface oxides [2]. We have studied oxygen-induced shape changes of Pt nanoparticles on MgO(100) by means of in situ x-ray diffraction. The experiment was performed at 300°C and oxygen pressures ranging from UHV to 500 mbar. The experimental results are compared to the theoretically predicted ones reported in [3].

[1] G. Rupprechter, in: Advances in Catalysis, eds. B. Gates and

H. Knözinger, Vol. 51 (Elsevier, Amsterdam, (2007) p.134).

[2] P. Nolte et al., Science 321, 1654 (2008).

[3] N. Seriani et al., Journal of Physics: Condensed Matter 20, 184023

(2008).