Regensburg 2013 – scientific programme
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O: Fachverband Oberflächenphysik
O 56: Oxide Surfaces I
O 56.9: Talk
Wednesday, March 13, 2013, 18:00–18:15, H45
Water adsorption on ultra-thin ZrO2/Pt3Zr — •joong il jake choi, hao li, christian weilach, ulrike diebold, and michael schmid — Technische Universität Wien, Wien, Austria
Despite its importance in many areas of industry such as catalysis, fuel cell technology and microelectronics, the surface properties of ZrO2 are yet not well understood. We have prepared ultra-thin ZrO2 films by oxidation of a Pt3Zr(0001) crystal [1] and studied adsorption and desorption of water on this surface by STM, XPS and AES. Water on ZrO2/Pt3Zr(0001) appears as a bright species on STM. Adsorption strongly depends on the structure of the substrate below the oxide; the lowest coverage is found in areas with unreconstructed Pt(111) below the oxide. Depending on the predominant substrate structures, we find a saturation coverage at room temperature between 0.14 and ≈ 0.25 ML with respect to the oxide lattice. The water species are adsorbed on equivalent sites of the oxide lattice, often also in equivalent sites with respect to the alloy substrate, thus influenced by the superstructure lattice (moiré). XPS suggests that the species observed by STM are the hydroxyl group. We have also created stable oxygen vacancies by electron irradiation of the ZrO2 film and studied the adsorption of H2O on this surface with defects.
[1] M. Antlanger et. al., Phys. Rev. B 86, 035451 (2012)