Design of porous FeNi-carbon nanosheets by a double-effect synergistic strategy for electromagnetic wave absorption

The electromagnetic pollution problem caused by the wide application of electromagnetic waves has seriously affected human life and prompted people to research efficient electromagnetic absorption materials. In this work, a porous FeNi-carbon nanosheet was designed and synthesized by a double-effect synergistic strategy. The three raw materials achieved perfect structural synergy, organically combining the magnetic medium with carbon materials. FeNi nanoparticles are evenly distributed on hierarchical pore carbon nanosheets. This unique structure dramatically reduces the materials’ density and improves impedance matching. The minimum density of porous FeNi-carbon nanosheets (FeNi-CNSs) is 36.3 mg cm3, comparable to that of carbon aerogels. More importantly, the synergistic attenuation mechanism of dielectric loss and magnetic loss promotes the efficient attenuation of FeNi-CNSs to electromagnetic waves. The minimum reflection loss (RLmin) of FeNi-CNSs is −47.27 dB at 3.0 mm, and the effective absorption bandwidth (EAB) is as high as 7.1 GHz at 2.5 mm. More surprisingly, when the thickness is in the range of 1.8–3.0 mm, the average EAB reaches 6.22 GHz, which expands the operational range of practical applications and provides the possibility for the application and promotion of lightweight magnetic carbon nanosheet microwave absorbing materials.