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O: Fachverband Oberflächenphysik
O 45: Solid-Liquid Interfaces II: Reactions and Electrochemistry
O 45.11: Vortrag
Dienstag, 17. März 2020, 13:15–13:30, WIL C107
A DFT study of early steps of Au island nucleation on c(2×2)-Cl Au(001) surface — •Alexandra C. Dávila and Eckhard Pehlke — Institut für Theoretische Physik und Astrophysik, CAU Kiel, Germany
Electrodeposition experiments of Au on a Au(001) electrode in a Cl− containing electrolyte have shown a dependence of the growth mode on sample potential and Au deposition rate [1]. While island nucleation is essential for layer-by-layer growth, a detailed atomic-scale description of the early steps leading to the formation of Au ad-structures on the c(2×2)-Cl covered Au(001) electrode surface is still lacking (for Au adsorption structures at low Cl coverage see [2]). We present DFT calculations, carried out with PWscf [3], of Aun adatom structures for n≤4 on the c(2×2)-Cl Au(001) surface without as well as in the presence of a small number of Cl vacancies, and investigate the stability as a function of Cl chemical potential. The electrolyte has not been included in the simulations. In the absence of Cl vacancies AuadCl2 chains form on the surface. In the range of Cl chemical potential where Cl vacancies become part of the equilibrium atomic adsorption structure, we find Cl vacancies to modify and to bind to the Au ad-structures. In this case, the energy gain due to the addition of a Auad monomer increases from about 0.06 eV to about 0.23 eV. I.e, the presence of Cl vacancies tends to promote Au ad-structure formation.
[1] K. Krug et al., Phys. Rev. Lett. 96, 246101 (2006).
[2] Mesgar et al., ChemPhysChem 11, 1395 (2010).
[3] P. Giannozzi et al., J. Phys. Condens. Matter 21, 395502 (2009).