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.