Fabrication of graphene aerogel and graphene/carbon nanotube composite aerogel by freeze casting under ambient pressure and comparison of their properties

Graphene aerogels are super lightweight and highly compressible 3D graphene structure. In this research, graphene aerogels and graphene/single-walled carbon nanotubes (G/SWCNTs) nanocomposite aerogels were produced by freeze casting under ambient pressure without the need for vacuum apparatus. The mechanical experiments showed that both aerogels can withstand a strain of up to 90%, but in general, G/SWCNTs aerogels have greater elasticity than the pure graphene aerogels. It was found that graphene aerogels had better electrical conductivity than G/SWCNTs aerogels and there was a threshold voltage of approximately 2 V, below which no electrical current could be established but by applying stress, the electrical current increased almost linearly by increasing the stress. Adsorption capacity of diesel oil, petroleum, edible oil and ethanol by graphene and G/SWCNTs aerogels were measured and found that among them, the diesel oil uptake by the aerogels was the highest. The highest adsorption capacity of graphene and G/SWCNTs aerogels were measured 85.5 gg(-1) and 30.5 gg(-1), respectively.