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 42.95: Poster
Mittwoch, 25. März 2009, 17:45–20:30, P2
DFT Studies of TiO2 (110) and Cu Surfaces — •Piotr Kowalski1, Bernd Meyer2, and Dominik Marx1 — 1Lehrstuhl fuer Theoretische Chemie, Ruhr-Universitaet Bochum, D-44780 Bochum — 2Interdisziplinäres Zentrum für Molekulare Materialien und Computer-Chemie-Centrum, Department Chemie und Pharmazie, Friedrich-Alexander-Universität Erlangen-Nürnberg
Using DFT-based ab-initio calculations in combination with a thermodynamic formalism we investigate the properties of TiO2 (110) and Cu surfaces. We have calculated the relative stability of various structural models of the nonpolar, mixed-terminated TiO2 (110) surface in contact with a surrounding gas phase at finite temperature and pressure. Adsorption and desorption of H, H2O, CO, simple alcohols as well as the formation of O vacancies were considered. Assuming thermodynamic equilibrium between the surface and an oxygen, hydrogen and water containing atmosphere, we constructed a phase diagram of the lowest free energy surface structures. Cu surfaces are interesting from technological point of view as methanol, a key material for the synthesis of organic materials, is made catalytically from gas containing CO, CO2 and H2 in presence of a Cu/ZnO/Al2O3 catalyst. It is believed that the morphological changes of the Cu particles on the ZnO support due to a strong metal-support interaction (wetting/dewetting) is the source of higher catalytic activity. We use DFT-based ab-initio calculations to identify the reactive sites on the Cu particles. In particular we investigate the adsorption of hydrogen and dissociated formic acid on clean as well as defective (steps/terraces) Cu surfaces.