Designable synthesis of reduced graphene oxide modified using CoFe2O4 nanospheres with tunable enhanced microwave absorption performances between the whole X and Ku bands

Facing the increasingly serious electromagnetic radiation, synthesis of graphene-containing microwave absorber with strong reflection loss (RL) and broad effective absorption bandwidth (EAB) have attracted tremendous interest due to their potential application in various areas. Herein, CoFe2O4@rGO hybrid nanocomposites composed of reduced graphene oxide (rGO) and embedded CoFe2O4 nanospheres were synthesized through an one-step solvothermal strategy. Enhanced microwave absorption properties of the nanocomposites with different CoFe2O4 nanospheres contents were investigated systematically, the RL value as well as the corresponding EAB could be effectively tuned by adjusting the filler contents of CoFe2O4@rGO hybrid nanocomposites. Remarkably, the minimal RL value of 67.58 dB accompanying with the corresponding EAB of 6.3 GHz (almost covering the whole Ku band) and the minimal RL value of 55.70 dB accompanying with the EAB of 4.0 GHz (almost covering the whole X band) can be achieved by the optimal sample with 10 wt% filler content at 2.1 mm and 2.7 mm matching thickness, respectively. The synergistic effect of impedance matching, hybrid microstructure together with various loss mechanisms are of crucial significance to enhance the absorption performances. The results suggest that the hybrid nanocomposites can serve as a promising lightweight and high-efficiency candidate absorber, and the simple synthesis technique gives a valuable clue for obtaining ideal microwave absorber.