Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 9: Solid-Liquid Interfaces: Structure, Spectroscopy I
O 9.6: Vortrag
Montag, 20. März 2017, 11:45–12:00, WIL C307
Stability and Structure of TiO2 Rutile (011) Surface Exposed to Liquid Water — •Jan Balajka, Martin Setvín, Martin Čalkovský, Zdeněk Jakub, Matthias Müllner, Stijn Mertens, Michael Schmid, and Ulrike Diebold — Institute of Applied Physics, TU Wien, Austria
Understanding the interface between titanium dioxide (TiO2) and liquid water is important for many practical applications such as photocatalytic water splitting.
The (011) termination of TiO2 rutile is the second lowest energy facet and exhibits a (2x1) reconstruction when prepared in UHV. Based on DFT predictions [1] the (2x1) structure should no longer be favorable in a liquid water environment.
A TiO2 rutile (011) sample, prepared and characterized in UHV, was exposed to liquid water and consequently analyzed with STM, XPS, LEIS and LEED. For this purpose a dedicated UHV system was used that allows controlled and clean transfer of the samples between the UHV and an electrochemical cell.
The results indicate a surface restructuring upon contact with liquid water. An overlayer of dissociated water is formed with a c(2x1) symmetry. As the splitting of the LEED spots corresponding to the (2x1) structure was observed while the bulk (1x1) spots did not change it is likely that the (2x1) substrate is also affected by the presence of liquid water. By combining XPS and LEIS the possibility of contaminant-induced restructuring was excluded.
[1] U. Aschauer, A. Selloni, PRL 106 (2011), 166102.