Ferroferric oxide/multiwalled carbon nanotube vs polyaniline/ferroferric oxide/multiwalled carbon nanotube multiheterostructures for highly effective microwave absorption

Light-weight nanocomposites filled with carbon nanotubes (CNTs) are developed for their significant potentials in electromagnetic shielding and attenuation for wide applications in electronics, communication devices, and specific parts in aircrafts and vehicles. Specifically, the introduction of a second phase into/onto CNTs for achieving CNT-based heterostructures has been widely pursued due to the enhancement in either dielectric loss or magnetic loss. In this work, ferroferric oxide (Fe₃O₄) was selected as the phase in multiwalled carbon nanotube (MWCNT)-based composites for enhancing magnetic properties to obtain improved electromagnetic attenuation. A direct comparison between the two-phase heterostructures (Fe₃O ₄/MWCNTs) and polyaniline (PANI) coated Fe₃O ₄/MWCNTs, namely, three-phase heterostructures (PANI/Fe ₃O₄/MWCNTs), was made to investigate the interface influences of Fe₃O₄ and PANI on the complex permittivity and permeability separately. Compared to PANI/Fe₃O ₄/MWCNTs, Fe₃O₄/MWCNTs exhibited enhanced magnetic properties coupled with increased dielectric properties. Interfaces between MWCNTs and heterostructures were found to play a role in the corresponding properties. The evaluation of microwave absorption of their wax composites was carried out, and the comparison between Fe₃O ₄/MWCNTs and PANI/Fe₃O₄/MWCNTs with respect to highly efficient microwave absorption and effective absorption bandwidth was discussed.