Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 24: Focus Session: Structure and Chemistry of Metal-Oxide Surfaces I
O 24.8: Vortrag
Dienstag, 13. März 2018, 13:00–13:15, MA 005
Transition metal clusters on tetragonal and monoclinic zirconia (ZrO2) surfaces — •Zhiyu Zou, Peter Lackner, Sabrina Mayr, Ulrike Diebold, and Michael Schmid — Institute of Applied Physics, TU Wien, 1040, Vienna, Austria
Zriconia (ZrO2) is widely used in heterogeneous catalysis, gas sensors and solid oxide fuel cells, where it is interfaced to transition metals. However, most investigations of ZrO2/metal systems focus on powder samples, where surface-science techniques of high spatial (e.g. STM) or energetic (e.g. XPS) resolution are limited by the morphology and insulating nature of the samples.
We have developed a method to prepare clean, atomically flat ZrO2 films (5-6 trilayers) with a precise control of phases (tetragonal or monoclinic) on Rh(111). The films are thin enough for STM and XPS measurements, yet show bulk-like crystallography. Transition metal (Rh, Fe, Au, Ag) clusters were deposited on both phases of ZrO2. STM and XPS indicate Ag has the weakest interaction with the substrates, and Fe the strongest. In comparison with ultrathin (single-trilayer) ZrO2 films on Pt3Zr and Pd3Zr[1], here Fe and Au are less affected by the underlying metallic substrate, resulting in higher density of Fe clusters and 3D cluster growth of Au. On tetragonal films, XPS shows small shifts of Zr3d and O1s core-level peaks; they shift much more on monoclinic films. Our work indicates the possibility of tailoring the electronic properties of transition metals by manipulating oxide support thickness and phases.
[1] J. J. Choi, et al. J. Phys. Chem. C 2016, 120, 9920