Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 18: Focus Session: Frontiers in Reducible Oxide Surface Science II
O 18.9: Vortrag
Montag, 12. März 2018, 17:45–18:00, HE 101
Activation of O2 adsorbed on (Ca,Sr)3Ru2O7 surfaces: a DFT study — •Wernfried Mayr-Schmölzer1,2, Daniel Halwidl2, Florian Mittendorfer1,2, Ulrike Diebold2, Josef Redinger1,2, and Michael Schmid2 — 1Center for Computational Materials Science, TU Wien, Vienna, Austria — 2Institute of Applied Physics, TU Wien, Vienna, Austria
Transition metal perovskite oxides are promising materials for a wide range of applications as diverse as fuel cells and catalysts. Surprisingly not much work has been done on their surface properties regarding oxygen transport and redox properties. Recently the adsorption of O2 as a charged molecule has been predicted by DFT on defective SrTiO3[1], and La2NiO4[2] surfaces. Here, we present a theoretical analysis including many-electron methods of O2 adsorption on defect-free rocksalt-like SrO and CaO surfaces of Ruddelsden-Popper type Sr3Ru2O7(001) and Ca3Ru2O7(001). We observe the adsorption of molecular O2 as a charged superoxo species on both defect-free materials. The DFT adsorption energies are high, up to 1.4 eV on both oxides, which we attribute to the overestimation of the electron affinity of O2 by standard semi-local functionals, making the charging of the O2 adsorbate too easy. Using beyond-DFT methods such as hybrid (HSE) functionals and advanced many-electron methods (RPA, G0W0) to properly describe the adsorption properties, we calculate an RPA adsorption energy of 0.72 eV in very good agreement with experimental values.
[1] Staykov, A., Chemistry of Materials, 27(24), 8273-8281.
[2] Akbay, T., J. Mater. Chem. A, 4(34), 13113-13124.