Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 8: Metal Substrates I: Adsorption and Reactivity

O 8.4: Vortrag

Montag, 1. April 2019, 11:15–11:30, H25

Modeling the formation and reactivity of surface oxide islands on metal surfaces — •Albert Bruix and Karsten Reuter — Technical University of Munich (Germany)

The surfaces of many transition metals are oxidized under ambient conditions or at increased oxygen pressures, which has strong implications for corrosion and catalysis. Stable O-enriched states resulting from oxidation may consist of the metal surface with high concentration of adsorbed O atoms, the corresponding metal-oxide, or something in between. The latter include surface oxides, i.e. ultrathin oxide layers formed on the surface of the metal.

A quantitative atomistic modeling of oxidation reactions catalyzed on such transition metals therefore requires an understanding of the chemical properties and formation mechanisms of the oxidized surfaces. In this work, PdO(101) surface oxide islands on the Pd(100) surface are studied by means of Density-Functional Theory calculations. We first establish a thermodynamic model for the formation and growth of surface oxide islands, focusing on the stability of different island edge types. We then use a multi-lattice microkinetic modeling approach to investigate the role of the metal and surface oxide phases, and how their coexistence under different operation conditions affects catalytic performance. Our approach also allows probing the relevance of sites at the interface between the two phases and the effect of phase transitions on the overall reactivity.