Photothermal hierarchical carbon nanotube/reduced graphene oxide microspherical aerogels with radially orientated microchannels for efficient cleanup of crude oil spills

Abstract High viscosity and low fluidity of heavy crude oils usually hinder their rapid diffusion into porous adsorbents, causing a low efficiency of oil spill remediation. Photothermal effect is thus adopted to rapidly reduce the viscosity of heavy crude oil by in situ solar light heating. Photothermal carbon nanotube/reduced graphene oxide (CNT/RGO) microspherical aerogels are synthesized by fabrication of graphene oxide (GO)-based microspherical aerogels with numerous radially orientated microchannels, followed by growing CNTs inside the microchannels and high-temperature reduction of the GO components. Thanks to the efficient photothermal conversion effect and the rough and oleophilic surface of the microchannels with large surface area, such aerogels facilitate the solar light absorption and hence enhance the crude oil adsorption. Furthermore, the CNTs grown on the RGO skeleton by a chemical vapor deposition approach promote the photothermal conversion efficiency by trapping and absorbing broadband solar light. Under 1 sun irradiation, the surface temperature of the aerogel quickly rises to 83 °C in 1 min, resulting in a sharp decrease in crude oil viscosity. The optimal microspherical aerogels deliver an extraordinary adsorption capacity of heavy crude oil, up to 267 g g-1 within 10 min, superior to those of other oil adsorbents reported so far.