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O: Fachverband Oberflächenphysik

O 40: Semiconductor substrates: Adsorption

O 40.1: Vortrag

Dienstag, 13. März 2018, 15:15–15:30, MA 005

Defect density dependence of partial oxidation and deoxygenation reactions of small organic compounds on rutile TiO₂ (110) surfaces — •Lars Mohrhusen, Milena Osmić, and Katharina Al-Shamery — Carl von Ossietzky University of Oldenburg, Institute of Chemistry, D-26129 Oldenburg, Germany

Though titanium dioxide is among the most interesting (photo-) catalyst materials, many structural details of the occurring thermic and photo-stimulated reactions remain unclear. For our mechanistic studies under ultra-high vacuum (UHV) conditions we use a rutile TiO₂ (110) single crystal surface to investigate the adsorption and reaction of small organic molecules such as methanol or methylamine with respect to the defect density.

Defect states like bridging oxygen vacancies as well as Ti^+III interstitials can easily be introduced to this material via argon ion sputtering and subsequent annealing in UHV. Around 300 K the Ti^+III interstitials start to be mobile and can diffuse towards the surface. We shall present our latest results illustrating the importance of such diffusive bulk defects for thermal reactions of organic molecules such as deoxygenation C-C coupling reactions or partial oxidation in different temperature regimes for alcohols in comparison to amines. Furthermore, we demonstrate the importance of different oxygen species present at the surface for these reactions, using low energy electron diffraction (LEED), temperature programmed desorption spectroscopy (TPD) and in addition Fourier-transformation polarized infrared reflection-absorption spectroscopy (FT-IRRAS).