Preparation and microwave absorption properties of ZnO@Fe₃O₄@RGO composites

Different processes are used to design unique microstructures of absorbing materials to meet the requirements of "thin, light, wide and strong" and improve the absorption efficiency of electromagnetic waves. The ZnO@Fe₃O₄ nanomaterial with a unique spindle flower structure was successfully prepared by a hydrothermal method and an annealing process. Then, the ZnO@Fe₃O₄@RGO composite was obtained by loading the prepared ZnO@Fe₃O₄ nanomaterial on the RGO surface. The crystal structure, morphology, electromagnetic parameters and microwave absorption properties of the synthesized nanocomposites were characterized by changing the amounts of Zn(CH₃COO)·2H₂O and GO, respectively. The wave absorption properties of pure Fe₃O₄, ZnO@Fe₃O₄ and ZnO@Fe₃O₄@RGO composites were compared. It was found that the ZnO@Fe₃O₄@RGO composite exhibits stronger microwave absorption performance. When mixed with paraffin wax at 50 wt%, the thickness of the absorption layer was only 2.5 mm, the reflection loss (RL) at 11.36 GHz reached -57.91 dB, and the effective absorption bandwidth was 4.24 GHz (9.44-13.68 GHz). ZnO@Fe₃O₄ nanocrystals can inhibit the agglomeration of RGO and improve the impedance matching between the heterostructural interface and RGO. Therefore, the composite can be used as an effective microwave absorber.