Porous graphene-based materials by thermolytic cracking

Porous graphene monolith and porous composites of graphene oxide (GO) and silica were prepared by thermolytic cracking of graphene-coated, or GO/silica-coated polystyrene (PS) spheres. The spheres were synthesized through in situ precipitation polymerization of styrene using GO and poly (vinylpyrrolidone) as stabilizing agents. During polymerization, GO adsorbed to the surface of the PS particle due to its amphiphilicity as well as spontaneous grafting on GO basal plane. The GO-coated PS spheres were either reduced by hydrazine to graphene-coated PS spheres, or underwent a sol-gel reaction with tetraethyloxysilane (TEOS). These materials were finally subjected to thermolytic cracking in a thermogravimetry instrument or in a furnace under nitrogen up to 550 or 700 degrees C, resulting in graphene-based porous materials in which the pores are surrounded by graphene or GO/silica walls. The factors affecting the specific surface area were discussed. The method may serve as a new approach to fabricate 3D graphene-based porous materials.