Influence of (RGO)/(ferrite) ratios and graphene reduction degree on microwave absorption properties of graphene composites

The reduced graphene oxide (RGO)/cobalt ferrite (CoFe2O4) composites with three different (RGO)/(CoFe2O4) ratios were synthesized by a one-pot hydrothermal route. To research the influence of graphene reduction degree on electromagnetic parameters of graphene composites, RGO/CoFe2O4-2 was treated further by reduction process with different reducing agents (N2H4/NaBH4). The crystalline structure, morphology, thermal stability, magnetic property of the synthesized samples were characterized by XRD, TEM, SEM, FT-IR, Raman, TG, VSM and XPS. The absorption properties of the RGO/CoFe2O4 composites were studied. The maximum R-L of RGO/COFe2O4-2 composite is -47.9 dB at 12.4 GHz with a thickness of 2.3 mm, and the absorption bandwidth with the R-L below -10 dB is up to 5.0 GHz (from 12.4 to 17.4 GHz) with a thickness of 2.0 mm. The results indicated that the RGO/CoFe2O4 composites have remarkably electromagnetic performance, which are attributed to effective complementarities between the dielectric loss and the magnetic loss. Additionally, the microwave absorption properties of the RGO/CoFe2O4 composites can be tuned easily by varying the (RGO)/(CoFe2O4) ratio, the reduction degree of graphene and layer thickness of the samples. (C) 2015 Elsevier B.V. All rights reserved.