Fabrication of nitrogen-doped reduced graphene oxide/cobalt ferrite hybrid nanocomposites as broadband electromagnetic wave absorbers in both X and Ku bands

Abstract

In this work, nitrogen-doped reduced graphene oxide decorated by magnetic cobalt ferrite (NRGO/CoFe2O4) hybrid nanocomposites were fabricated through solvothermal and hydrothermal two-step processes. Results of structure and micromorphology analysis manifested that numerous nanosized CoFe2O4 particles were uniformly anchored on the wrinkled surfaces of flake-like NRGO, and considerable nitrogen atoms had been doped into the crystal lattice of RGO. Moreover, the influences of additive amounts of CoFe2O4 and hybridization with NRGO on the electromagnetic parameters and absorption properties were carefully examined. Significantly, the as-synthesized nanocomposite with the content of NRGO of 13.76 wt% exhibited the optimal electromagnetic absorption capacity, i.e. the minimum reflection loss achieved −48.4 dB and broadest absorption bandwidth reached 6 GHz (12–18 GHz) under a small matching thickness of merely 1.9 mm and low filler content of 30 wt%. It should be mentioned that full absorption of both X and Ku bands was realized in the as-fabricated nanocomposites by facilely modulating the additive amounts of CoFe2O4 and matching thicknesses. Furthermore, the hybrid nanocomposites showed strong absorption intensity (≤ −20 dB, 99% absorption) in a wide thickness range of 1.9–5 mm. Besides, the potential electromagnetic absorption mechanisms were uncovered. Therefore, our results opened a novel idea for designing RGO-based dielectric/magnetic hybrid nanocomposites as high-performance electromagnetic absorbers.