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O: Fachverband Oberflächenphysik
O 121: Solid-Liquid Interface IV: Structure and Spectroscopy
O 121.5: Vortrag
Freitag, 20. März 2020, 11:45–12:00, TRE Phy
Understanding metal dissolution at Mg/H2O interfaces from first-principles modelling — •Sudarsan Surendralal, Mira Todorova, and Jörg Neugebauer — Deparment of Computational Materials Design, Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf-40237, Germany
The fundamental reaction that governs the corrosion of metals in an aqueous environment is the electrochemical dissolution reaction. Using our recently developed ab initio potentiostat scheme [1], we study the atomistic mechanism of metal dissolution at the vicinal Mg(1 2 -3 15)/water interface using density functional theory based molecular dynamics simulations under conditions of anodic polarization. Our results show water dissociation and the subsequent adsorption of OH groups at low coordinated kink sites of the electrode. This adsorption process is found to make these sites prone to dissolution. Analysis of our calculated trajectories confirms that a kink Mg atom dissolves as a divalent cation with a six-fold solvation shell. In addition, the anomalous hydrogen evolution reaction reported for anodically polarized Mg/H2O interfaces is also observed. Based on our observations, we propose a reaction mechanism of Mg dissolution involving water dissociation.
[1] S. Surendralal, M. Todorova, M. W. Finnis, J. Neugebauer, Phys. Rev. Lett. 120, 246801 (2018)