Intercalating Hybrids of Sandwich-like Fe₃O₄–Graphite: Synthesis and Their Synergistic Enhancement\nof\nMicrowave Absorption

Abstract

Rational\ndesign on the components and microstructures of microwave-absorbing\nmaterials can pave the way for upgrading their performances in electromagnetic\npollution prevention. In this study, Fe₃O₄–graphite\nintercalation hybrids (Fe₃O₄-GIH) with unique\nsandwich-like microstructure are fabricated by a molten salt route\nand subsequent temperature reduction. It is found that the gaseous\nFeCl₃ molecules at high temperature can diffuse into the\ngraphite interlayer plane to obtain FeCl₃-GIH, and the\nintercalated FeCl₃ is then transferred into Fe₃O₄ nanoparticles under high temperature reduction, which\ncan prop open the graphite interlayer, thus achieving sandwich-like\nFe₃O₄-GIH. Therefore, one-step synthesis can\ngive perfect features, such as transformation of graphite into graphene\nsheets, introduction of a magnetic component, and construction of\nmultiple interfaces, which are a benefit to the microwave absorption\n(MA). As a result, the maximum reflection loss of the as-obtained\nFe₃O₄-GIH can be up to −51 dB at 4.3\nGHz with a matching thickness of 4.8 mm. Furthermore, the MA performances\ncan be tuned by regulating the interlayer spacing of Fe₃O₄-GIH. The excellent microwave absorption performance\nmay attribute to the synergistic effect between Fe₃O₄ nanoparticles with magnetic loss, graphite with dielectric\nloss, and novel interfacial polarization originating from the sandwich-like\nFe₃O₄-GIH. Additionally, it can be supposed\nthat these sandwich structures are more beneficial for scattering\nthe incident electromagnetic wave due to their large spacing and porous\nfeatures.