Construction of three-dimensional hierarchical porous nitrogen-doped reduced graphene oxide/hollow cobalt ferrite composite aerogels toward highly efficient electromagnetic wave absorption

Abstract

The development of graphene-based composites with low density, robust absorption, wide bandwidth and thin thickness remained a great challenge in the field of electromagnetic (EM) absorption. In this work, nitrogen-doped reduced graphene oxide/hollow cobalt ferrite (NRGO/hollow CoFe₂O₄) composite aerogels were constructed by a solvothermal and hydrothermal two-step route. Results demonstrated that the as-fabricated composite aerogels had the ultralow density and a unique three-dimensional (3D) network structure, and lots of hollow CoFe₂O₄ microspheres were almost homogeneously distributed on the wrinkled surfaces of lamellar NRGO. Moreover, superior EM absorbing capacity could be achieved by modulating the ferrite structure, addition amounts of hollow CoFe₂O₄ and thicknesses. It was noteworthy that the NRGO/hollow CoFe₂O₄ composite aerogel with the addition amount of ferrite of 15.0 mg possessed the minimum reflection loss of -44.7 dB and maximum absorption bandwidth of 5.2 GHz (from 12.6 to 17.8 GHz) at a very thin thickness of 1.8 mm and filling ratio of 15.0 wt.%. Furthermore, the possible EM attenuation mechanism had been proposed. The results of this work would be helpful for developing RGO-based 3D composites as lightweight, thin and highly efficient EM wave absorbers.