Hierarchical graphene@Fe3O4nanocluster@carbon@MnO2 nanosheet array composites: Synthesis and microwave absorption performance

The fabrication of novel hierarchical graphene@Fe₃O₄ nanocluster@carbon@MnO₂ nanosheet array composites has been successfully carried out for the first time. The fabrication process involves the deposition of Fe₃O₄ nanoclusters on graphene's surface using a simple in situ hydrothermal method, subsequent introduction of carbon on the surface of graphene@Fe3O4 nanoclusters by combining the hydrothermal reaction and thermal treatment process, and finally formation of the hierarchical composites via a simple in situ redox replacement reaction between potassium permanganate (KMnO4) and carbon on the surface of graphene@Fe₃O₄ nanoclusters. Moreover, the microwave absorption properties of both graphene@Fe₃O₄ nanoclusters and hierarchical graphene@Fe₃O₄ nanocluster@carbon@MnO₂ nanosheet array composites were investigated between 2 and 18 GHz microwave frequency bands. The electromagnetic data demonstrate that graphene@Fe₃O₄ nanocluster@carbon@MnO₂ nanosheet array hierarchical composites exhibit significantly enhanced microwave absorption properties compared with graphene@Fe₃O₄nanoclusters, which probably originate from the unique hierarchical structure and larger surface area.