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

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