Dresden 2014 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 49: Surface Chemical Reactions and Heterogeneous Catalysis III

O 49.1: Vortrag

Mittwoch, 2. April 2014, 10:30–10:45, PHY C 213

Hydrogen adsorption on bimetallic PdAg/Pd(111) surface alloys — •Luis Mancera and Axel Groß — Institute of Theoretical Chemistry, University of Ulm, D-89069 Ulm, Germany

Hydrogen adsorption on metallic surfaces has been a very active field of research due to the wide range of technical applications, in areas such as heterogeneous catalysis, energy storage and energy conversion. Bimetallic surface alloy catalysts have in various cases been found to show superior catalytic properties compared to those of the individual species, with the additional advantage of being tunable by doing changes in their compositions. In this contribution, we investigate hydrogen adsorption on PdAg/Pd(111) bimetallic surface alloys, a system that has been found to be thermodynamically stable and to exhibit a catalytic performance that is related to the size of the palladium ensembles [1]. We use periodic density functional theory (DFT) in order to elucidate mechanisms for molecular hydrogen dissociation and to identify active sites for adsorption as a function of palladium ensemble size and hydrogen coverage. In most of cases, similarly to adsorption on pure Pd(111), hydrogen atoms adsorb preferentially at threefold-coordinated hollow sites of palladium ensembles, while adsorption of molecular hydrogen is observed only at top position of isolated Pd atoms in the surface alloy.

[1] L. Mancera et al., Phys. Chem. Chem. Phys. 15, 1497 (2013).