Role of Urea in the Preparation of Highly Porous Nanocomposite Aerogels

Abstract
The preparation of highly porous CoFe2O4−SiO2 nanocomposite aerogels was successfully achieved by a novel sol−gel procedure involving urea-assisted co-gelation of the precursor phases. This method allows fast gelation, giving rise to an aerogel with 97% porosity. The formation of CoFe2O4 nanocrystals homogeneously distributed within the matrix occurs after calcination at 750 °C and is complete at 900 °C. Despite the high temperature required for the formation of the CoFe2O4 nanocrystals, the high porosity typical of aerogels is still retained.