Size Control of Pt Clusters on CeO2 Nanoparticles via an Incorporation–Segregation Mechanism and Study of Segregation Kinetics
| Autor: | Agnese Carino, Andrea Testino, Antonio Cervellino, Christian Proff, Frank Pilger, Christian Ludwig, Anastasios Kambolis |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Absorption spectroscopy
Chemistry Reducing atmosphere Kinetics Analytical chemistry Ionic bonding 02 engineering and technology General Chemistry Activation energy Thermal treatment 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Catalysis 0104 chemical sciences Nanomaterials Chemical engineering 0210 nano-technology |
| Zdroj: | ACS Catalysis |
| ISSN: | 2155-5435 |
| DOI: | 10.1021/acscatal.6b00934 |
| Popis: | Recent literature on Pt/CeO2 catalysts reveals that ionic Pt species could be incorporated into the CeO2 lattice. Here we present a detailed study of Pt segregation in air and under a reducing atmosphere conducted on thermally treated samples by high resolution X ray diffraction (XRD) and X ray absorption spectroscopy. We further perform a kinetic study by in situ XRD measurements with the aim of estimating the activation energy for Pt cluster segregation and coalescence in air which was found to be ~3.88 eV. This high activation energy indicates that Pt clusters are strongly anchored on the CeO2 surface and that their mobility is activated only at >900 °C. We clearly show the correlation between the nature of the segregated Pt particles and the applied thermal treatment for Pt/CeO2 nanomaterials prepared by the wet chemical route. On the basis of thorough characterization we present a possible segregation pathway under oxidizing conditions as opposed to a mere surface reduction during a reducing treatment leading to the coalescence of less anchored Pt. The catalytic performances confirm the remarkable activity and thermal stability of entities obtained via an incorporation–segregation mechanism. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|