Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 118: Metal substrates: Structure, epitaxy and growth

O 118.2: Vortrag

Freitag, 16. März 2018, 11:15–11:30, MA 005

Surface segregation and electromechanical coupling at the Ag-Au (111) surface — •Sandra Hoppe and Stefan Müller — Institute of Advanced Ceramics, Hamburg University of Technology, Hamburg, Germany

Recently, the sponge-like nanoporous gold (npAu) has attracted the attention for heterogeneous catalysis due to its promising characteristics, such as high catalytic activity at ambient temperature and pressure and a high surface-to-volume ratio¹. Residual silver that is left after the fabrication process has been found to influence the catalytic activity and selectivity of npAu². In order to better understand this phenomenon, it is crucial to analyze the way silver is distributed in the Ag-Au alloy surface and how segregation affects the surface composition. For this purpose, we have employed a combination of first-principles calculations and statistical physics to investigate surface segregation at the Ag-Au (111) surface. Interestingly, we obtain Au enrichment in the topmost layer, which we explain with a charge transfer from Ag to Au, stabilizing Au in the surface layer. Furthermore, we analyzed the influence of the surface composition and Ag surface concentration on the electromechanical coupling behavior, which offers an opportunity to alter the catalytic activity by applying strain to a surface.

[1] B. Zielasek et al. Angew. chem. Int. Ed. 45 (2006) 8241.

[2] L.-C. Wang et al. Beilstein J. Nanotechnol. 4 (2013) 111.