Ostwald ripening in a Pt/SiO2 model catalyst studied by in situ TEM

Sintering of Pt nanoparticles dispersed on a planar SiO2 support was studied by in situ transmission electron microscopy (TEM). A time-lapsed TEM image series of the Pt nanoparticles, acquired during the exposure to 10 mbar synthetic air at 650 °C, reveal that the sintering was governed by the Ostwald ripening mechanism. The in situ TEM images also provide information about the temporal evolution of the Pt particle size distribution and of the growth or decay of the individual nanoparticles. The observed Pt nanoparticle changes compare well with predictions made by mean-field kinetic models for ripening, but deviations are revealed for the time-evolution for the individual nanoparticles. A better description of the individual nanoparticle ripening is obtained by kinetic models that include local correlations between neighboring nanoparticles in the atom-exchange process.

Sintering of Pt nanoparticles on SiO2 support was studied by in situ transmission electron microscopy (TEM) under oxidizing conditions. Time-lapsed TEM images reveal that the sintering is governed by Ostwald ripening and is better described by kinetic models, including local correlations between the Pt particles.Figure optionsDownload high-quality image (143 K)Download as PowerPoint slideHighlights
► Oxygen-induced sintering in a Pt/SiO2 model catalyst is studied by in situ TEM.
► Time-resolved TEM images show that Pt sintering was governed by Ostwald ripening.
► The time-evolution of the nanoparticles compared with kinetic ripening models.
► The ripening is influenced by local correlations between neighboring particles.