Regensburg 2010 – scientific programme
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O: Fachverband Oberflächenphysik
O 12: Oxides and insulators: Adsorption
O 12.5: Talk
Monday, March 22, 2010, 16:00–16:15, H33
A comparative study of short-chained alcohols and water adsorbed on TiO2(110) by He atom scattering and DFT — •David Silber1, Franziska Traeger1, Christof Wöll3, Piotr Kowalski2, and Dominik Marx2 — 1Department for Physical Chemistry I at the university of Bochum — 2Department for Theoretical Chemistry at the university of Bochum — 3Institute of Functional Interfaces Karlsruhe at the Karlsruher Institute of Technology
In this combined experimental and theoretical study the adsorption of methanol and ethanol on well defined TiO2(110) was investigated. Theoretical and experimental results will prove that methanol adsorbs molecularly in a c(2x2)-superstructure. Heating the surface to 300 K leads to the deprotonation of methanol. Further heating to 350 K (binding energy - 1 eV) leads to a recombinative desorption process in which solely methanol is detected. In additional experiments predosing of D2O was performed to fill bridge bonded oxygen vacancy sites and to investigate the interaction of water with methanol. TDS reveals that water and methanol compete for adsorption sites, but a pure methanol layer was never formed on water precovered TiO2. These experimental finding is supported by our DFT calculation, which proves that a mixed methanol and water structure is stable. This work is complemented by the analogue investigation of ethanol adsorption on clean and water precoverd TiO2. On clean rutile solely the desorption of ethanol in a recombinative desorption process was detected. Like methanol ethanol competes with water for adsorption sites, but unlike methanol, ethanol is able to completely replace water in the first layer.