Fabrication of nitrogen-doped reduced graphene oxide/porous magnesium ferrite@silica dioxide composite with excellent dual-band electromagnetic absorption performance

In order to solve the increasingly serious problem of electromagnetic radiation pollution, it is urgent to develop advanced electromagnetic wave (EMW) absorbers with low filling ratio, wide bandwidth and strong absorption. In this work, nitrogen-doped reduced graphene oxide/porous magnesium ferrite@silicon dioxide (NRGO/MgFe2O4@SiO2) composite was prepared by a three-step route of solvothermal reaction, Stöber method and hydrothermal synthesis. The results of microscopic morphology analysis showed that a large number of MgFe2O4@SiO2 core–shell microspheres were uniformly distributed on the wrinkled surface of NRGO in the ternary composite. Furthermore, the effect of dielectric SiO2 coating on the electromagnetic parameters and EMW absorption performance of NRGO/MgFe2O4 composite was also investigated. Significantly, the EMW absorption capacity of the obtained ternary composite was better than that of the other two binary composites. When the filling ratio was 20.0 wt.% and the matching thickness was 2.0 mm, the ternary composite exhibited the widest absorption bandwidth of 6.2 GHz and the strong absorption strength of -58.8 dB at 14.6 GHz (Ku band). It was worth noting that when the thickness was increased to 4.2 mm, the optimal reflection loss of -61.0 dB was achieved at 5.8 GHz (C band). In addition, the potential EMW absorption mechanism was also proposed. Therefore, this work would provide a valuable reference for the preparation of graphene-based magnetic composites as lightweight, broadband and efficient EMW absorbers.