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O: Fachverband Oberflächenphysik
O 86: Heterogeneous catalysis I
O 86.5: Vortrag
Donnerstag, 17. März 2011, 17:30–17:45, WIL B122
Non-equilibrium surface pattern formation during catalytic reactions with nanoscale resolultion — Jean-Sabin McEwen1, •Pierre Gaspard1, Thierry Visart de Bocarmé2, and Norbert Kruse2 — 1Center for Nonlinear Phenomena and Complex Systems, Université Libre de Bruxelles, Campus Plaine CP 231, 1050 Bruxelles, Belgium — 2Chemical Physics of Materials, Université Libre de Bruxelles, Campus Plaine CP 243, 1050 Bruxelles, Belgium
Despite the large progress made in the recent years to provide a sound understanding of the oscillatory behavior of various catalytic surface reactions, there still are a number of questions apparently unsolved. One of these open questions concerns the gap between the choice of catalyst in surface science studies and those used in heterogeneous catalysis. Indeed, in surface science, oriented single crystals are mainly used while multi-facetted metal particles are present in catalysis. A field emitter tip on the other hand can be regarded as a good approximation of a nanometer-sized metal particle. Stunningly, a field emitter tip is also large enough to allow the emergence of regular oscillations from the molecular fluctuations. This is the case when a rhodium nanosized crystal is exposed to hydrogen and oxygen. Here, we show that the observed nonequilibrium oscillatory patterns find their origin in the different catalytic properties of all of the nanofacets that are simultaneously exposed at the tip’s surface. These results suggest that the underlying surface anisotropy, rather than a standard reaction-diffusion mechanism, plays a major role in determining the self-organizational behavior of multifaceted nanostructured surfaces.