Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 10: Solid-liquid Interfaces I

O 10.4: Talk

Monday, March 31, 2014, 11:15–11:30, WIL A317

Implicit solvation model for the first-principles description of methanol electro-oxidation on Pt electrodes — •Sung Sakong and Axel Groß — Institut für Theoretische Chemie, Universität Ulm, 89069 Ulm, Germany

Within a conventional density functional theory (DFT) framework, the atomistic description of the electrochemical reactions in a direct methanol fuel cell often ignores the presence of the aqueous environment or the dispersion interactions between reaction intermediates and electrode that can be crucial for a realistic modeling. Recently, Arias has introduced a joint scheme to treat solute/solvent simultaneously with combining DFT calculations and an implicit solvent based on the polarizable continuum model [Modelling Simul. Mater. Sci. Eng. 21 (2013) 074005], which allows to assess electrochemical systems including the electrolyte within a first-principles approach.

Using the method, we address the electro-oxidation of methanol on Pt electrodes and compare it to the corresponding reaction steps at Pt in vacuum. Practically, we model the electrode as a Pt(111) surface and investigate the energetics of the reaction intermediates with and without implicit solution. Furthermore, we test the influence of an explicit water bilayer at the interface in addition to the implicit solution on the energetics. The contribution of dispersion interaction to the stability of reaction intermediates and the height of reaction barriers in both vacuum and an aqueous environment will also be addressed using a correction scheme suggested by Tkatchenko and Scheffler [Phys. Rev. Lett. 102 (2009) 073005].