Synthesis of nitrogen-doped reduced graphene oxide/magnesium ferrite/polyaniline composite aerogel as a lightweight, broadband and efficient microwave absorber

The fabrication of graphene-based microwave absorbing materials with low density, small filling ratio, broad bandwidth and strong absorption remains a huge challenge. In this work, nitrogen-doped reduced graphene oxide/magnesium ferrite/polyaniline (NRGO/MgFe2O4/PANI) composite aerogel was synthesized by a three-step method of solvothermal reaction, in situ chemical oxidation polymerization and hydrothermal self-assembly. The results showed that the obtained aerogels had a unique three-dimensional (3D) porous network structure and low bulk density (11.1–13.0 mg cm−3). It was worth noting that in the NRGO/MgFe2O4/PANI ternary composite aerogel, MgFe2O4 coated with a thin PANI layer was anchored on the surface of NRGO sheets. Furthermore, the NRGO/MgFe2O4/PANI ternary composite aerogel showed much better microwave absorbing capacity compared with pure NRGO aerogel and NRGO/MgFe2O4 binary composite aerogel. When the filling ratio was as low as 11.5 wt.%, the obtained ternary composite aerogel exhibited the maximum effective absorption bandwidth of 7.0 GHz at a matching thickness of 2.1 mm, and the minimum reflection loss of -42.9 dB at a thickness of 3.57 mm. Additionally, the probable microwave dissipation mechanism was also elucidated. It was believed that this study would pave the way for the construction of 3D graphene-based composites as lightweight, broadband and efficient microwave absorbents.