NO Oxidation Catalysis on Pt Clusters: Elementary Steps, Structural Requirements, and Synergistic Effects of NO2 Adsorption Sites
| Autor: | Brian M. Weiss, Enrique Iglesia |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
Chemistry
Inorganic chemistry chemistry.chemical_element Photochemistry Oxygen Dissociation (chemistry) Surfaces Coatings and Films Electronic Optical and Magnetic Materials Catalysis Metal General Energy Adsorption Reaction rate constant visual_art Desorption Vacancy defect visual_art.visual_art_medium Physical and Theoretical Chemistry |
| Zdroj: | The Journal of Physical Chemistry C. 113:13331-13340 |
| ISSN: | 1932-7455 1932-7447 |
| Popis: | Kinetic and isotopic methods show that NO oxidation on supported Pt clusters involves kinetically relevant reaction of O2 with vacancy sites on surfaces nearly saturated with oxygen adatoms (O*). The oxygen chemical potential at Pt surfaces that determines the O* coverage is rigorously described by an O2 virtual pressure and determined by the thermodynamics of NO2−NO interconversion reactions. NO oxidation and oxygen isotopic exchange processes are described by the same rate constant, consistent with similar kinetically relevant O2 dissociation steps for both reactions. NO oxidation, NO2 decomposition, and 16O2−18O2 exchange rates increased markedly with increasing Pt cluster size (1−8 nm); these clusters remain metallic at all O2 virtual pressures prevalent during NO oxidation. These effects of cluster size reflect the higher vacancy concentrations and more facile oxygen desorption on larger Pt clusters, which bind oxygen adatoms weaker than more coordinatively unsaturated surface Pt atoms on smaller clu... |
| Databáze: | OpenAIRE |
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