# Growing CeO$$_2$$ Nanoparticles within the Nano-Porous Architecture of the SiO$$_2$$ Aerogel

Caddeo, Francesco, Loche, Danilo, Casula, Maria F., Corrias, Anna (2020) Growing CeO$$_2$$ Nanoparticles within the Nano-Porous Architecture of the SiO$$_2$$ Aerogel. Frontiers in Chemistry: Nanoscience, 8 . ISSN 2296-2646. (doi:10.3389/fchem.2020.00057) (KAR id:79603)

In this study, new CeO$$_2$$-SiO$$_2$$ aerogel nanocomposites obtained by controlled growth of CeO$$_2$$ nanoparticles within the highly porous matrix of a SiO$$_2$$ aerogel are presented. The nanocomposites have been synthesized via a sol-gel route, employing cerium (III) nitrate as the CeO$$_2$$ precursor and selected capping agents to control the growth of the CeO$$_2$$ nanoparticles, which occurs during the supercritical drying of the aerogels. Samples with different loading of the CeO$$_2$$ dispersed phase, ranging from 5 to 15%, were obtained. The nanocomposites showed the morphological features typical of the SiO$$_2$$ aerogels such as open mesoporosity with surface area values up to 430 m$$^2$$·g$$^{-1}$$. TEM and XRD characterizations show that nanocrystals of the dispersed CeO$$_2$$ 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$$_2$$ 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$$_2$$ 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.