Growing CeO Nanoparticles Within the Nano-Porous Architecture of the SiO Aerogel.

In this study, new CeO-SiO aerogel nanocomposites obtained by controlled growth of CeO nanoparticles within the highly porous matrix of a SiO aerogel are presented. The nanocomposites have been synthesized via a sol-gel route, employing cerium (III) nitrate as the CeO precursor and selected surfactants to control the growth of the CeO nanoparticles, which occurs during the supercritical drying of the aerogels. Samples with different loading of the CeO dispersed phase, ranging from 5 to 15%, were obtained. The nanocomposites showed the morphological features typical of the SiO aerogels such as open mesoporosity with surface area values up to 430 m·g. TEM and XRD characterizations show that nanocrystals of the dispersed CeO nanophase grow within the aerogel already during the supercritical drying process, with particle sizes in the range of 3 to 5 nm. TEM in particular shows that the CeO nanoparticles are well-distributed within the aerogel matrix. We also demonstrate the stability of the nanocomposites under high temperature conditions, performing thermal treatments in air at 450 and 900°C. Interestingly, the CeO nanoparticles undergo a very limited crystal growth, with sizes up to only 7 nm in the case of the sample subjected to a 900°C treatment.