Preparation, characterization, and properties of graphene-based composite aerogels via in situ polymerization and three-dimensional self-assembly from graphene oxide solution

Abstract

Three-dimensional reduced graphene oxide/phenolic resin (RGO/PR) composite aerogels were synthesized through a simple and facile one-pot polymerization-induced phase separation (PIPS) of a phenolic prepolymer with hexamethylenetetramine (HMTA) as a catalyst in an ethylene glycol (EG) suspension of graphene oxide (GO), followed by solvent exchange and ambient pressure drying. The RGO/PR composite aerogels showed an interpenetrating framework with high meso- and macroporosity. By adjusting the amounts of GO in the co-precursor solution, aerogels with different textural properties were prepared. A self-assembly mechanism based on the adsorption and chemical interactions between GO sheets, PR and HMTA, as well as PIPS in the precursor solution was proposed to explain the formation of the composite aerogels. Furthermore, enhancement of GO on the thermal stability of the RGO/PR composite aerogels were studied, the characteristic thermal degradation temperature and char yield of the RGO/PR composite aerogels are higher than that of the as-prepared PR aerogels. The anchored effect of chemical bonds and π–π stacking of PR polymer chains at the interface of GO sheets and PR resin, and the induced effect of GO on PR char formation and graphitization should be a contributing factor to the enhancement. Graphene/carbon composite aerogels were also fabricated by carbonization of the aerogels at 1000 °C in argon. A hierarchical porous microstructure with large micropores was achieved by pyrolysis gas evolution, phenolic particle shrinkage and preservation of the meso- and macroporous structure during the carbonization.