Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 9: Solid-Liquid Interfaces: Structure, Spectroscopy I

O 9.1: Vortrag

Montag, 20. März 2017, 10:30–10:45, WIL C307

Self-Diffusion Mechanisms of Surface Defects at Copper-Water Interfaces — •Suresh Kondati Natarajan and Jörg Behler — Lehrstuhl für Theoretische Chemie, Ruhr Universität Bochum, Germany

The self-diffusion mechanisms of surface defects at metal-water interfaces have to be studied for understanding heterogeneous catalysis, electrochemistry and corrosion. Although a number of studies in the literature have been dedicated to the investigation of these mechanisms at metal-vacuum interfaces, there are hardly any studies for metal-water interfaces. Here, we unravel the surface adatom and vacancy diffusion mechanisms at several copper-water interfaces using a high dimensional neural network potential based on density functional theory [1]. In case of the low index surfaces such as (111), (100) and (110), the adatom diffusions by means of a simple hop and an exchange with a surface atom are investigated and we find that the free energy barrier to the hopping mechanism is much smaller than the barrier to the exchange mechanism. We find that the interfacial water molecules assist in the adatom diffusion processes. The adatoms at stepped surfaces like (311) and (211) hop along the step edge more frequently compared to the hop across the step edge. Finally, the vacancy hop at (100) surface is found to be twice as probable as the hop at (111) and (110) surfaces in the presence of water.

[1] S. K. Natarajan and J. Behler, Phys. Chem. Chem. Phys. 18, 28704 (2016).