Tunable microwave absorptivity in reduced graphene oxide functionalized with Fe3O4 nanorods

Adjustable and high-performance microwave absorbing materials of three-dimensional (3D) reduced graphene oxide (RGO)@Fe 3 O 4 structure were realized with different compositions. 100 × 50 nm Fe 3 O 4 nanorods were anchored on both sides of RGO sheets uniformly which stop RGO sheets from re-stacking. Effective absorption bands shifted to higher frequencies and thinner thicknesses in 2–18 GHz due to the precisely controlled complex permittivity caused by the decreased content of RGO. The maximum reflection loss of RGO@Fe 3 O 4 composites was up to −56.25 dB at 12.62 GHz with a small thickness of 2.0 mm, and the absorption bandwidth below −10 dB was 5.40 GHz with only 20 wt% filler loading in the paraffin matrix. The dielectric loss was a primary factor in the superior absorption performance resulting from dipolar polarization, interfacial polarization and associated relaxation phenomena. Hence, the appropriate composition of the RGO@Fe 3 O 4 structure can consider both the microwave absorptivity and the absorption adjustability. This method can be apply to other graphene-based magnetic microwave absorption materials.