Hannover 2016 – wissenschaftliches Programm
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MS: Fachverband Massenspektrometrie
MS 3: Ion Traps, Ion Storage Rings, Molecules, Clusters, Decays and Reactions
MS 3.1: Hauptvortrag
Montag, 29. Februar 2016, 15:15–15:45, f128
Mass-Spectroscopic Trace of Transient Reaction Kinetics of CO Oxidation Catalyzed by Uni-Sized Pt Clusters Directly Bound to Si Surface — •Hisato Yasumatsu — Cluster Research Laboratory, Toyota Technological Institute: in East Tokyo Laboratory, Genesis Research Institute, Inc. 717-86 Futamata, Ichikawa, Chiba 272-0001, Japan
I will present mass-spectroscopic studies on low-temperature and anti-poisoning catalytic activity driven by uni-sized Pt clusters directly bound to a Si substrate surface, PtN/Si (N=10−71). A tandem Quadruple mass spectrometer was employed; the first one (16000 Da) selects the cluster size, N, so that uni-sized PtN+ are impacted onto a Si(111) surface for their fixation on the surface, and the second one (500 Da with high transmittance) analyzes catalysis products. The highly selective, sensitive and reproducible detection of the products allows tracing their intensity transients after changing the partial pressures of reactants. In CO oxidation as an example, the transient measurements in combination with numerical simulation led to reaction rate constants of the four elemental steps; CO adsorption/desorption, O2 dissociative adsorption and Langmuir-Hinshelwood reaction for the CO2 production. It was found that Pt60/Si and Pt30/Si possess the catalytic activity 40-K lower than the Pt(111) single-crystal surface. This result was interpreted as the CO anti-poisoning nature of the monatomic-layered PtN/Si due to efficient activation of oxygen by electrons accumulated in a Schottky barrier junction at the sub-nano interface between PtN and the Si surface.