Novel Air@rGO€Fe₃O₄ microspheres with excellent microwave absorbing properties and corrosion resistance were synthesized by a W/O emulsion technique followed by a calcination process.

High-performance, lightweight, and broadband microwave absorption materials have drawn significant research focus. Graphene aerogels may give us inspiration for the design of highly efficient synergistic microwave absorption materials due to their low density and adjustable dielectric properties along with tunable porosity, providing abundant active sites for supporting functional magnetic components. Herein, we report a facile chemical reduction-assembly route, followed by in situ thermal decomposition for the fabrication of super-hydrophobic magnetic graphene aerogels. Owing to the improved attenuation characteristic and the synergistic effect, the fabricated magnetic graphene aerogels exhibited greatly enhanced microwave absorption performance. The hybrids with only 4.25 wt% of functional fillers reached a minimum reflection loss value of −51.6 dB at 14.6 GHz with an absorber thickness of 2.4 mm and a maximum effective absorption bandwidth (EAB, below −10 dB) of 6.5 GHz. Compared with other reported graphene-based absorbers, such high-performance synergistic microwave absorbers that are super-hydrophobic and lightweight with low filler loading may rapidly increase the research interest for future practical applications.

In this study, we report a simple and efficient two-step method consisting of water-in-oil (W/O) emulsion technique and subsequent annealing process for synthesizing the hollow reduced graphene oxide microspheres embedded with Co nanoparticles (Air@rGO€Co). The microspheres showed good electromagnetic properties because of the coexistence of magnetic loss and dielectric loss to microwaves. The minimum reflection loss (RL_min) value of S_1.5 reaches −68.1 dB at 13.8 GHz with a thickness of 2.2 mm, and the absorption bandwidth (lower than −10 dB) is 7.1 GHz covering from 10.9 GHz to 18.0 GHz. More interestingly, we can easily controll the microwave absorbing properties of the microspheres by changing the ratio of the two components in the composites. The excellent electromagnetic match at the corresponding resonance peaks for dielectric and magnetic loss play an important role in improving microwave absorption property. Our study provides a good potential method for preparation of lightweight microwave absorbing materials.

The efficient preparation of electromagnetic wave absorbing materials with low density and excellent electromagnetic wave absorption remains a considerable challenge. In this study, reduced graphene oxide (RGO) wrapped Fe₃O₄ nanoparticles (NPs) were synthesized based on one-step reaction by the reduction of graphene oxide (GO), and the generation of super-fine Fe₃O₄ NPs was achieved. The phase structure, chemical composition, micromorphology, and magnetism were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscope (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM), and vibrating sample magnetometer (VSM), respectively. The electromagnetic characteristics were evaluated on a vector network analyzer by the coaxial line method. The results showed that super-fine Fe₃O₄ NPs with an average size of 6.18 nm are densely distributed on the surface of graphenes. The RGO/Fe₃O₄ nanocomposites exhibited excellent microwave absorption properties with a minimum reflection loss (RL) of up to −55.71 dB at 6.78 GHz at 3.5 mm thickness and the highest effective absorption bandwidth with RL values exceeding −10 dB is 4.76 GHz between 13.24 and 18 GHz at 1.7 mm thickness. This work provides a concise method for the development of RGO supported super dense Fe₃O₄ nanocomposites for high performance electromagnetic absorption applications.