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O: Fachverband Oberflächenphysik

O 75: Metal Substrates: Growth Studies

O 75.5: Vortrag

Mittwoch, 18. März 2020, 16:00–16:15, WIL C107

Investigation of the stability of bimetallic surface alloys: A kinetic Monte Carlo study — •David Mahlberg and Axel Groß — Institut für Theoretische Chemie, Universität Ulm, 89069 Ulm, Germany

Bimetallic surfaces are attractive substrates for catalytic purposes, due to the possibility to tailor their structure and hence, their stability and reactivity on an atomic scale. This offers great potential, e.g., with respect to rational catalyst design. However, operation conditions are often extreme in terms of temperature and pressure. Therefore, it is necessary to have detailed knowledge about the properties and stability of surface alloys when composition and/or temperature is modified. In our work, we use first principles-based kinetic Monte-Carlo (kMC) simulations to analyse AgPd/Pd(111), PtRu/Ru(0001), and InCu/Cu(100) bimetallic surface alloys.

We have studied the stability of these surface alloys by monitoring the changes that occur via vacancy diffusion. In order to simulate vacancy diffusion, first-principles electronic structure calculations are used to derive the energy barriers that enter kMC simulations. Thus, the structure formation of surface alloys on macroscopic time scales and mesoscopic length scales as a function of composition and temperature can be monitored for varying concentrations of the alloyed metal, respectively. The energy barriers and diffusion behaviour are analysed in terms of the interaction between constituents that change with the particular local arrangements.