Dresden 2017 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
O: Fachverband Oberflächenphysik
O 89: Oxide and Insulator Surfaces: Adsorption III
O 89.7: Talk
Thursday, March 23, 2017, 12:00–12:15, TRE Phy
Water adsorption at the Zirconia Surface on Pt3Zr — •Peter Lackner1, Jan Hulva1, Joong-Il J. Choi1,2, Gareth Parkinson1, Ulrike Diebold1, and Michael Schmid1 — 1Institute of Applied Physics, TU Wien, Vienna, Austria — 2Institute for Basic Science, KAIST, Daejeon, Republic of Korea
Oxidation of Pt3Zr(0001) single crystals leads to the formation of a ZrO2(111) trilayer on top of a Pt layer [1]. In scanning tunneling microscopy (STM), the ZrO2 layer shows a (√19x√19)R23.4∘ superstructure with 12 Zr atoms in every unit cell. The Zr layer is strongly buckled and the ZrO2 trilayer is distorted above substrate dislocation lines, thus creating different adsorption locations.
We have employed this ZrO2/Pt3Zr system as a model system for water adsorption studies on zirconia, combining temperature-programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS) and STM. In TPD, ≈90% of the adsorbed D2O contributes to the monolayer peak at 180 K (Eads = 0.5 – 0.6 eV). According to XPS, these adsorbates are bound in molecular form. The remaining 10% are bound in the form of hydroxyls. They have higher binding energies, which leads to a tail in the TPD spectrum reaching up to 550 K.
Repeated TPD measurements lead to a decrease of the monolayer peak area and to an increase of the tail area. Thus, water changes the surface structure, creating adsorption sites with higher adsorption energies. This surface change was examined by low-temperature STM.
[1] Antlanger et al., Phys. Rev. B 86, 035451 (2012).