Determination of the Particle Size, Available Surface Area, and Nature of Exposed Sites for Silica−Alumina-Supported Pd Nanoparticles: A Multitechnical Approach
| Autor: | A. Zecchina, Serena Bertarione, Carlo Lamberti, Riccardo Pellegrini, Luca Bertinetti, G. Leofanti, Giovanni Agostini, Elena Groppo |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
Materials science
Extended X-ray absorption fine structure nanoparticle Coordination number Analytical chemistry particle size chemisorption HR-TEM Surfaces Coatings and Films Electronic Optical and Magnetic Materials EXAFS Crystallography General Energy Chemisorption Particle-size distribution Particle Particle size Physical and Theoretical Chemistry Fourier transform infrared spectroscopy Dispersion (chemistry) |
| Zdroj: | The Journal of Physical Chemistry C. 113:10485-10492 |
| ISSN: | 1932-7455 1932-7447 |
| DOI: | 10.1021/jp9023712 |
| Popis: | In this work we used several complementary techniques (TEM, TPR, CO chemisorption, EXAFS and FTIR spectroscopy) to understand the effects of the activation temperature and activation atmosphere (air or H2) on the particle size distribution, the fraction, and the type of exposed surface sites of Pd nanoparticles supported on a high surface area SiO2−Al2O3 (SA) support. Pd particle distribution has been carefully determined by a high statistic TEM study, from which the cuboctahedral-like shape of the metal particles is demonstrated. Assuming a model of perfect cuboctahedral particles, from the TEM particle size distribution we estimated the expected average Pd first shell coordination number. This value is slightly larger than that directly found by EXAFS owing to the fraction of very small Pd particles (d < 6−8 A) that basically escape TEM detection. The same geometrical model allows prediction, from TEM particle size distribution, of the metal dispersion observed by CO chemisorption (S/VChemi). The S/VChe... |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|