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O: Fachverband Oberflächenphysik
O 109: Heterogeneous Catalysis on Metal Oxides
O 109.8: Vortrag
Donnerstag, 19. März 2020, 16:45–17:00, TRE Phy
Trends in Oxidation of Transition-Metal Surfaces at Realistic Temperature and Pressure Conditions — •Zhong-Kang Han1,2, Santiago Rigamonti3, Maria Troppenz3, Claudia Draxl3, Matthias Scheffler2, and Sergey V. Levchenko1,2 — 1Skolkovo Institute of Science and Technology, Moscow, RU — 2Fritz-Haber-Institut der MPG, Berlin, DE — 3Humboldt Universität zu Berlin, Berlin, DE
Oxidation of transition-metal surfaces is a ubiquitous phenomenon, but its thermodynamics is still not fully understood. Using the all-electron FHI-aims code, we present a systematic DFT study (comparing various xc approximations) of the adsorption of oxygen at different elemental and alloyed metal surfaces. The effects of configurational entropy are evaluated by combining a cluster expansion (CE) model with Monte Carlo sampling and the Wang-Landau algorithm, as implemented in our python package CELL [1]. Configurational disorder for both alloy components and adsorbates within several atomic layers of the surface is explicitly taken into account. We show that long-range repulsive interactions between the negatively charged oxygen anions are essential to explain the stability of ordered structures of adsorbed O atoms at (110) and (111) surfaces of elemental metals. The stronger the repulsive interaction is, the higher is the temperature of order-disorder phase transitions. The structures of adsorbed O at the Pd- or Pt-alloyed Cu surfaces exhibit a larger variety of patterns depending on coverage, with Pd/Pt segregating to the surface at low oxygen coverages. 1. http://sol.physik.hu-berlin.de/cell