Ultra-low-density GNS/CA composite aerogels with ultra-high specific surface for dye removal

Abstract

Ultra-low-density graphene nanosheet (GNS)/carbon composite aerogels (CAs) were prepared via GO (graphene oxide)/RF (resorcinol–formaldehyde) aerogel composite, supercritical fluid drying, and carbonization. Graphene oxide was found to act as an efficient anti-shrinkage additive in the carbonization process, making the linear shrinkage ratios decrease from 78 % to only 10 % (25 % GO content). The density of the aerogels thus decreases from 115 to 24.4 mg cm−3. 25 % GO-composited aerogel exhibits over two times modulus increase and over 11 times specific modulus increase in comparison with pure carbon aerogel. The microstructure results show that GO is fully cross-linked with RF polymers, makes the reaction more sufficient and ultimately strengthens the nanostructure to withstand the damage of carbonization. The resultant composite carbon aerogels exhibited super high specific surface area (as high as 2899 m2 g−1), good mechanical property, and high adsorption capacity of 403 mg g−1 for methylene blue.