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O: Fachverband Oberflächenphysik
O 50: Oxide and Insulator Surfaces I
O 50.3: Vortrag
Mittwoch, 2. April 2014, 11:00–11:15, WIL A317
Water Adsorption at the Tetrahedral Titania Surface Layer of SrTiO3(110)-(4×1): An STM and Photoemission Study. — •Stefan Gerhold1, Zhiming Wang1, Xianfeng Hao1, Zbynek Novotny1, Cesare Franchini2, Eamon McDermott3, Karina Schulte4, Michael Schmid1, and Ulrike Diebold1 — 1Institute of Applied Physics, Vienna University of Technology, Austria — 2Center for Computational Materials Science, University of Vienna, Austria — 3Institute of Materials Chemistry, Vienna University of Technology, Austria — 4MAX IV Laboratory, Lund University, Sweden
The interaction of water with oxide surfaces is of great interest for both fundamental sciences and applications. We present a combined theoretical [density functional theory (DFT)] and experimental [Scanning Tunneling Microscopy (STM), photoemission spectroscopy (PES)] study of water interaction with the two-dimensional titania overlayer that terminates the SrTiO3(110)-(4 × 1) surface and consists of TiO4 tetrahedra. STM, core-level and valence band PES show that H2O neither adsorbs nor dissociates on the stoichiometric surface at room temperature, while it dissociates at oxygen vacancies. This is in agreement with DFT calculations, which show that the energy barriers for water dissociation on the stoichiometric and reduced surfaces are 1.7 and 0.9 eV, respectively. We propose that two-dimensional tetrahedrally coordinated titania overlayers are generally hydrophobic. In addition, enhanced reactivity due to deposited Sr adatoms is discussed. This work was supported by the Austrian Science Fund (FWF, project F45).