Synthesis of a multifunctional graphene–carbon nanotube aerogel and its strong adsorption of lead from aqueous solution

Abstract

Mechanically enhanced aerogels of graphene sheets and carbon nanotubes (CNTs) were prepared via hydrothermal reduction of graphene oxide and CNTs in the presence of ferrous ions (FeSO₄ solution). The resultant graphene–CNT aerogels possess a 3-D network of carbon structures containing micro-sized pores and α-FeOOH nanorods within the matrix. The CNTs may act as a scaffold in the aerogels to resist compressive stress and prevent them from collapse. The aerogels have very low density (0.011–0.087 g cm⁻³), depending on the amount of ferrous ions used in the synthesis. In addition, the aerogels also have excellent mechanical properties with elastic modulus between 0.011 and 0.29 MPa. Because of their porous structures, the graphene–CNTs aerogels showed excellent removal ability to aqueous lead with rates between 230 and 451 mg g⁻¹ and thus could be potentially used as a promising adsorbent for many environmental applications.