Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 23: Solid-Liquid Interfaces II: Electrode Surfaces
O 23.6: Vortrag
Dienstag, 2. April 2019, 12:00–12:15, H5
DFT calculations of self-diffusion at an Au(001) electrochemical interface — •Alexandra C. Dávila and Eckhard Pehlke — Institut für Theoretische Physik und Astrophysik, CAU Kiel, Germany
In surface X-ray scattering experiments at the interface between an Au(100) electrode and HCl + HAuCl4 containing electrolyte Krug et al. [1] have observed that the growth mode depends on the electrode potential and Au-concentration. Transitions from 3D to layer-by-layer and to step-flow growth mode were observed at positive potentials (VAg/AgCl), where the unreconstructed substrate surface is stable. Pichardo-Pedrero et al. [2] have observed an increase of the decay rate of Au islands on Au(001) with sample potential and, in particular, when chloride is present the electrolyte. The atomic-scale mechanism of self-diffusion on coinage metal surfaces has been investigated by DFT calculations before [3, 4], however, the detailed role of the co-adsorbed anions on the diffusion is not yet fully understood. We present diffusion paths on c(√2× 2√2)R45∘-Cl and c(2×2)-Cl Au(001) surfaces. The dependence of the diffusion rate on sample potential as derived from the variation of the induced dipole moment along the paths gives an increase of the Au self-diffusion energy barrier with increasing potential. Thus, we speculate that other factors, like nucleation, determine the sample potential dependence of Au growth mode.
[1] K. Krug et al., Phys. Rev. Lett. 96, 246101 (2006).
[2] E. Pichardo-Pedrero et al., Appl. Phys. A, 87, 461 (2007).
[3] J. E. Müller et al., Phys. Rev. B 74, 085408 (2006).
[4] M. Mesgar et al., ChemPhysChem 14, 233 (2013).