Tunable microwave absorbing property of RGO/Fe₃O₄/SiO₂ nanocomposites by effective regulation of eddy current effect

The ternary RGO/Fe₃O₄/SiO₂ composites were prepared through a hydrothermal method and an annealing process. The Fe₃O₄ and SiO₂ particles were in situ grown on the surface of reduced graphene oxide (RGO). The RGO, Fe₃O₄, and SiO₂ were properly assembled to realize comprehensive electromagnetic wave-absorbing performance, which not only achieve synergy between the dielectric loss and the magnetic loss, but also possess satisfactory impedance matching. Based on the analysis of absorbing properties, the RGO/Fe₃O₄/SiO₂-0.5 composite exhibits the optimal wave absorbing performance with the maximum reflection loss of −34.36 dB and an effective absorption bandwidth of 7.76 GHz at a matching thickness of 2.9 mm. The introduction of wave transparent and insulated SiO₂ increases the propagation paths and optimizes the conductivity. Meanwhile, the construction of a heterogeneous interface promotes the interfacial polarization. The appropriate conductive network and the defect sites of RGO guarantee the conduction loss and dipole polarization. The natural resonance and exchange resonance from Fe₃O₄ jointly contribute to the magnetic loss. Therefore, this work provides a simple and flexible method for the synthesis and design of the heterostructure with multiple dissipation mechanism as a high-efficiency absorbent.