Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 58: Poster Session III (Solid/liquid interfaces; Metals; Semiconductors; Oxides and insulators)

O 58.49: Poster

Mittwoch, 28. März 2012, 18:15–21:45, Poster B

Charge Localization Dynamics Induced by Oxygen Vacancies on the TiO2(110) Surface and Titania and Gold-promoted Titania Surfaces Interaction with small molecules — •Matteo Farnesi Camellone — Ruhr-Universität Bochum D-44780 Bochum

We use ab initio molecular dynamics to investigate the dynamics of an F--center created by an oxygen vacancy on the TiO2(110) rutile surface. The simulations uncover a truly complex, time-dependent behavior of fluctuating electron localization topologies in the vicinity of the oxygen vacancy. Although the two excess electrons are found to populate preferentially the second subsurface la<x>yer, they occasionally visit surface sites and also the third subsurface layer [1]. We then study the interaction of CO with the (110) Au supported (110) TiO2 surface catalysts. The structural, electronic, dynamical and thermodynamic properties of the gold promoted titania surfaces are investigated by means of density functional theory calculations that account for the on site Coulomb interaction via the inclu sion of a Hubbard term (GGA+U). The interaction between gold and substrate is accompained by an extensive charge reorganization at the metal-oxide contact wich leads to Au oxidation and the reduction of the titanum dioxide substrate. It is shown that the catalytic activity of the (110) TiO2 substrate is efficiently improved by supported and dispersed Au adatoms on the same substrate. [2]

[1] P. M. Kowalski, M. Farnesi Camellone, N. N. Nair, B. Meyer, and D. Marx, Phys. Rev. Lett. , 146405 (2010). [2] M. Farnesi Camellone, P. M. Kowalski, and D. Marx, Phys. Rev. B 84, 035413 (2011)