Development of Fe/Fe3O4@C composite with excellent electromagnetic absorption performance

Abstract In this work, core-shell shaped Fe3O4@C composites have been firstly prepared by in-situ polymerization of phenolic resin on the surface of Fe3O4 and subsequent high-temperature carbonization. The core of Fe3O4 nanoparticles can be partial or totally reduced to metallic Fe in a N2/H2 atmosphere and resulted in Fe3O4-Fe@C and Fe@C products. These as-prepared Fe-Fe3O4@C and Fe@C products are analyzed by X-ray diffraction (XRD), and transmission electron microscopy (TEM). Furthermore, the electromagnetic microwave absorption properties of the core-shell nanocomposites are investigated in terms of the theory of transmission lines. Compared with pristine Fe3O4, Fe3O4@C and Fe@C, the Fe3O4-Fe@C ternary heterostructures exhibit the outstanding microwave absorption properties. The minimum reflection loss (RL) of −29.3 dB can be observed at the frequency of 12.6 GHz with the thickness of 3.9 mm. The bandwidth (RL ≤ −10 dB) can be monitored in the frequency of 3.6–18 GHz with the thickness of 1.5–4.0 mm. The excellent absorption is attributed to the synergistic effect of dielectric and magnetic loss, multiple interfacial polarization resonances, and good impedance match.