| AVS 55th International Symposium & Exhibition | |
| Surface Science | Tuesday Sessions |
| Session SS2-TuA |
| Session: | Dynamics and Novel Probes |
| Presenter: | J. Haubrich, University of Bonn, Germany |
| Authors: | J. Haubrich, University of Bonn, Germany D. Loffreda, Ecole Normale Supérieure de Lyon, France F. Delbecq, Ecole Normale Supérieure de Lyon, France Y. Jugnet, Ecole Normale Supérieure de Lyon, France P. Sautet, Ecole Normale Supérieure de Lyon, France C. Becker, University of Bonn, Germany K. Wandelt, University of Bonn, Germany |
| Correspondent: | Click to Email |
Studies on catalysis such as the selective hydrogenation of α,β -unsaturated aldehydes on transition metal surfaces represent a challenge to both experimentalists and theoreticians. In order to elucidate the underlying elementary reactions, the assignment of the adsorption structures of complex molecules on model-catalyst surfaces is a fundamental step. Insight into the molecule-surface bonding of these structures is crucial for instance to understand the different hydrogenation activities and selectivities of multifunctional molecules on various catalysts. Furthermore introducing alloying effects to catalyst surfaces can change the properties of catalysts significantly and, thereby give rise to additional modifications of the molecule-surface interaction. Here we present a complementary experimental and theoretical study on the molecule-surface interaction of different organic molecules including ethene, butadiene and the α,β-unsaturated aldehydes crotonaldehyde and prenal on Pt(111) and two ordered Pt-Sn surface alloys. With the combination of HREELS (high-resolution electron energy loss spectroscopy) experiments carried out on the three model-catalysts and complimentary density-functional theory (DFT) calculations of vibrational spectra, we identified the stable adsorption structures on Pt(111) as well as the Pt2Sn/Pt(111) and the Pt3Sn/Pt(111) surface alloys. Surprisingly, we find that the changes in the vibrational shifts for corresponding structures on the three surfaces induced by the alloying cannot be satisfactorily correlated with the changes in the adsorption energies. However, with a detailed energetic analysis of the molecule-surface bonding, new insights on the interaction strength with the substrate are obtained that allow to rationalize the behavior of the vibrational properties.