Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 81: Oxide and Insulator Surfaces: Adsorption II
O 81.10: Vortrag
Mittwoch, 22. März 2017, 18:15–18:30, WIL C107
Adsorption of Oxygen on Ruthenate Perovskite Surfaces — •Florian Mittendorfer, Wernfried Mayr-Schmölzer, Josef Redinger, Daniel Halwidl, and Ulrike Diebold — Institute of Applied Physics, TU Vienna
The surface chemistry of perovskite oxides plays a central role for promising applications, such as solid oxide fuel cells. In a recent study, we could demonstrate a high chemical activity of strontium ruthenate surfaces for the adsorption of CO [1] and H2O[2].In this presentation, I will discuss the adsorption of oxygen (O2) on the (001) surface of the Ruddlesden-Popper perovskites Sr3Ru2O7(SRO) and Ca3Ru2O7 (CRO) on the basis of density functional theory (DFT) calculations. Oxygen adsorbes as a charged molecular species on both surfaces, yet our results display pronounced differences between the two systems. In the low coverage case, the calculations predict a slight tilting of the O2 molecule on the SRO (001) surface, and the surface is uniformly covered at higher coverages. In contrast, the additional tilting of the Ru octahedra at the bare CaO terminated CRO (001) surface leads to a striped pattern of wide and narrow rows. This pattern strongly influences the respective adsorption energies of the O2 molecule, as the adsorption in the wide channels is significantly more stable than the adsorption in the narrow channels. Thus, in agreement with experiment, the saturation coverage is already reached at an oxygen coverage of 0.5 ML, where the occupation of symmetry- equivalent sites leads to the formation of a zig-zag arrangement of the O2 molecules. [1] Phys. Rev. Lett 113, 116101 (2014) [2] Nature Materials 15, 450 (2016)