Facile synthesis of nitrogen-doped reduced graphene oxide/nickel-zinc ferrite composites as high-performance microwave absorbers in the X-band

Nowadays, developing high-performance microwave absorbers with thin thickness, strong absorbing, broad bandwidth and low filler loading is of great importance for solving the problem of electromagnetic pollution. Herein, nitrogen-doped reduced graphene oxide/nickel-zinc ferrite (NRGO/Ni0.5Zn0.5Fe2O4) composite was synthesized using graphene oxide (GO) as a template by a facile two-step strategy. Results of morphology observations revealed that well-designed entanglement structure consisting of Ni0.5Zn0.5Fe2O4 microspheres and crumpled NRGO was clearly observed in the as-prepared NRGO/Ni0.5Zn0.5Fe2O4 composite. Moreover, the effects of complexing of NRGO and filler loadings on the microwave absorption properties of NRGO/Ni0.5Zn0.5Fe2O4 composite were carefully investigated. It was found that the complexing of NRGO notably enhanced the microwave absorption properties of Ni0.5Zn0.5Fe2O4 microspheres. Significantly, the obtained NRGO/Ni0.5Zn0.5Fe2O4 composite demonstrated the optimal minimum reflection loss of −63.2 dB with a matching thickness of 2.91 mm in the X-band and effective absorption bandwidth of 5.4 GHz (12.0–17.4 GHz) almost covering the whole Ku-band with a thin thickness of merely 2.0 mm. Furthermore, the relationship between filler loading and refection loss was carefully clarified. Besides, the underlying microwave absorption mechanisms of as-prepared composite were proposed. It was believed that our results could shed light on the design and fabrication of graphene-based magnetic composites as high-efficient microwave absorbers.