Magnetic nanoparticles, such as Fe₃O₄ and Co₃O₄, play a vital role in the research on advanced microwave absorbing materials, even if problems such as high density and narrow band impedance matching are still unsolved. Herein, the study of lightweight hollow Fe₃O₄@reduced graphite oxide (RGO) nanocomposites synthesized via the solvothermal method is presented. The microstructure and crystal morphology of the materials were characterized by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses. Single crystalline hollow Fe₃O₄ spheres were grown onto RGO flakes, leading to the formation of heterojunction, which further influenced the microwave absorption properties. The latter were evaluated by standard microwave characterization in the frequency range of 2⁻18 GHz. It was found that, for a specific Fe₃O₄@0.125 g RGO composite, the minimum reflection loss can reach -41.89 dB at 6.7 GHz, while the reflection loss was less than -10 dB from 3.4 GHz to 13.6 GHz for a nanocomposite sample thickness in the range of 1⁻4 mm. The combination of these two materials thus proved to give remarkable microwave absorption properties, owing to enhanced magnetic losses and favorable impedance matching conditions.
Keywords: heterojunction; hollow Fe3O4; microwave absorption; solvothermal.