Berlin 2018 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 88: Gerhard Ertl Young Investigator Award

O 88.2: Hauptvortrag

Donnerstag, 15. März 2018, 11:00–11:30, MA 005

Catalytic reactivity of binary alloys studied by field emission techniques — •Cédric Barroo, Yannick De Decker, Luc Jacobs, and Thierry Visart de Bocarmé — Université Libre de Bruxelles

Field emission techniques are well-suited to study the dynamics of catalytic reactions occurring at the surface of a nanosized metal tip which represents a good model of a single catalytic nanoparticle. Here, field ion microscopy (FIM) is used to determine the structure of the alloys, and field emission microscopy (FEM) to study the dynamics of reactions during the ongoing processes. We studied the NO2+H2 reaction on Pt-Rh. Previous experiments on Pt and Rh proved the presence and robustness of nonlinear dynamics, such as self-sustained periodic oscillations and propagation of chemical waves. On the Pt-Rh alloy, non-linear behaviors were observed: the characteristics of the oscillations lie between the features on pure Pt and Rh. The existence of periodic oscillations during the NO2+H2 reaction on Pt, Rh and Pt-Rh samples suggest that the mechanism behind the occurrence of those oscillations is robust and seems to mostly depend on the reaction itself and less on the nature of the substrate. The mechanism of reaction is discussed. We also studied the N2O+H2 reaction on Au-Ag, where N2O serves as a supplier of O(ads) since the ability to supply adsorbed oxygen is the key for activity/selectivity on gold surfaces. The reactive behavior can be observed via the appearance of new field emission patterns. These results prove the relevance of field emission techniques to study the catalytic activity of alloys.