Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 41: Poster Session I (Semiconductor Substrates: Epitaxy and growth; Semiconductor Substrates: Adsorbtion; Semiconductor Substrates: Solid-liquid interfaces; Semiconductor Substrates: Clean surfaces; Oxides and insulators: Epitaxy and growth; Oxides and insulators: Adsorption; Oxides and insulators: Clean surfaces; Organic, polymeric and biomolecular films - also with adsorbates; Organic electronics and photovoltaics, Surface chemical reactions; Heterogeneous catalysis; Phase transitions; Particles and clusters; Surface dynamics; Surface or interface magnetism; Electron and spin dynamics; Spin-Orbit Interaction at Surfaces; Electronic structure; Nanotribology; Solid/liquid interfaces; Graphene; Others)
O 41.49: Poster
Dienstag, 23. März 2010, 18:30–21:00, Poster B1
Locally resolved kinetics of catalytic CO oxidation on polycrystalline platinum — •Diana Vogel1,2, Christian Spiel1, Yuri Suchorski1, Wolfgang Drachsel1, Robert Schlögl2, and Günther Rupprechter1 — 1Institute of Materials Chemistry, Vienna University of Technology, Austria — 2Fritz Haber Institute (Max-Planck-Gesellschaft), Berlin, Germany
In this contribution we present a microscopic study of the kinetics of the catalytic CO oxidation reaction on a polycrystalline Pt foil consisting of (100)-, (110)- and (111)-type domains (∼100 µm) under reaction conditions (reactants pressure ∼10−5 mbar ). The study was performed by combination of photoemission electron microscopy (PEEM) with mass-spectroscopy (MS). PEEM allows an in situ observation of the local kinetic phase transitions in the reaction, MS, in turn, provides the global kinetics. By combining the laterally resolved (PEEM) and global (MS) data we elucidate the role of the individual domains in the reaction and elaborate the contributions of the particular domains to the global kinetics. We show that the global kinetic phase diagram can be composed as a superposition of the local kinetic phase diagrams of the individual domains.
Furthermore, we compare the catalytic behaviour of the polycrystalline Pt foil with that of a Pt(111) single crystal and a sputtered Pt foil to show the influence of the surface morphology on the reaction kinetics. Increasing surface roughness shifts the kinetic phase diagram to lower temperature and higher partial CO pressure.