Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 51: Surface chemical reactions I

O 51.5: Vortrag

Donnerstag, 26. März 2009, 17:15–17:30, SCH A01

Theoretical investigations on the electrochemical hydrogen evolution on Pt-hydride surfaces — •Fedor Strigunov, John Keith, and Timo Jacob — Institut für Elektrochemie, Universität Ulm, 89081 Ulm

Noble metals are a common component of electrodes that drive electrochemical reactions. Despite their nobility, electrode surfaces may take on many different structures or morphologies under electrochemical environments. Using periodic density functional theory, we calculated the surface free energies for several different surfaces of a variety of bulk Pt-hydride morphologies. In combination with the extended ab initio thermodynamics approach [1,2] we present a first phase diagram showing under which experimental temperature, activity, and electrode potential conditions hydrogen is present on the surface and which Pt-hydride surface orientation and structure is stabilized. On the basis of the most relevant Pt-hydride surfaces we then evaluated the adsorption of atomic hydrogen as well as the barriers for hydrogen evolution. This data will be used as the grounds for further understanding reactions on electrochemical electrodes.

[1] M. Scheffler, J. Dabrowski, Phil. Mag., A 58, 107 (1988). [2] T. Jacob, J. Electroanal. Chem., 607, 158, (2007).