Preparation and evaluation of Au nanoparticle–silica aerogel nanocomposite

•TMOS/ethanol solution was gelled together with Au nanoparticles.•The wet gel was dried in supercritical carbon dioxide.•The characteristics of the original aerogel were maintained in the nanocomposite.•The characteristics of Au nanoparticles were maintained in the aerogel nanocomposite.

A Au nanoparticle–silica aerogel nanocomposite was prepared by the gelling of a tetramethyl orthosilicate (TMOS)/ethanol solution together with Au nanoparticles and drying the wet gel in supercritical carbon dioxide. The aerogel nanocomposite contained Au nanoparticles at a concentration of 0.268 ppm. The bulk density, porosity, and specific surface area of the obtained nanocomposite were 0.126 g/cm3, 94%, and 890 m2/g, respectively. The nanocomposite was reddish-violet in color and transparent, and had a relative permittivity of approximately 6 with a dielectric loss of ca. 1 × 10−3 in the range of 10 MHz to 1 GHz.