Graphene–carbon nanotube aerogel as an ultra-light, compressible and recyclable highly efficient absorbent for oil and dyes

Abstract

Carbon nanotubes (CNTs) have good toughness and hydrophobicity. The embedding of CNTs into a graphene aerogel (GA) network could modify various properties of the GA. In this work, we report a facile and green approach to synthesize graphene–CNT aerogels (GCAs) by a one-step hydrothermal redox reaction. The prepared aerogels possess ultra-light densities ranging from 6.2–12.8 mg cm⁻³. The incorporation of CNTs into the GA could not only improve the morphologies, specific surface areas and hydrophobic properties but also enhance the adsorption capacity and mechanical properties of the GA. Under optimized GO/CNT mass ratio (7 : 1 and 3 : 1) conditions, adsorption capacities 100–270 times of their own weight could be achieved depending on the density of the adsorbed organics. The same trend also appeared in the adsorption of dyes including methylene blue (MB) and methyl orange (MO). Especially, the obtained GCAs exhibited excellent reusability and mechanical strength on the basis of absorption–combustion and adsorption–squeezing experiments. Even after 10 cycles, the macroscopic shape of the aerogels is well kept and almost no decrease in adsorption capacity was observed. Based on the facile preparation process, high adsorption capacity and stable cyclic performance, the GCAs could have promising widespread applications in practical water purification and oil remediation.