Clean Synthesis of Silver-Silica Aerogels via Supercritical Drying and Impregnation

Abstract

A simple and clean route to synthesize nano-scale mesoporous silver-silica composite aerogels was described here. The composite aerogels were obtained by adding a silver colloid to an about-to-gel silica sol prepared and then dried in supercritical anhydrous ethyl alcohol. The silver colloid and composite aerogels with silver content of 0wt%, 0.5wt%, 1wt% and 3.5wt% were characterized by UV-visible absorption spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD) and N2 Brunauer-Emmett-Teller (BET). The results show that silver nanoparticles with size about 40nm are successfully impregnated into the spongy porous structure of silica. The surface area decreases from 845 to 443m2/g with the increase of silver content. And the nanoscopic surface and bulk properties of each component are retained in the solid composite.