Synthesis and Structure of Carbon/Silica Hybrid Aerogels

Abstract

Hybrid hydrogels were synthesized by sol-gel polymerization of resorcinol and formaldehyde added by colloidal silica solutions. Carbon/silica hybrid aerogels were prepared from the hydrogels by supercritical drying and carbonization. Carbon aerogels and silica aerogels were obtained by removing silica with HF etching and carbon with air burning from the hybrid aerogels respectively. Carbon xerogels were prepared by ambient drying,carbonization and HF etching from the hydrogels. The microstructures of the four kinds of gels were characterized by TEM and N2 adsorption. It is found that the carbon and silica frameworks are continuous and interpenetrated each other. The silica framework can improve the strength of hybrid gels,which can decrease the volume shrinkages by preventing collapse of the hybrid framework during supercritical drying and carbonization,resulting in carbon aerogels with high specific surface area of 934m2/g and large total pore volume of 3.9cm3/g.