High-performance EMI shielding effectiveness of Fe 3 O 4 -3D rPC nanocomposites: a systematic optimization in the X-band region.

In this work, the microwave absorption (MWA) performance of a Fe 3 O 4 -3D reduced porous carbon nanocomposite (3D rPC NC) in the X-band region is reported. Three different shields are fabricated by altering the ratio of Fe 3 O 4 nanoparticles (NPs) and 3D rPC and evaluating their microwave (MW) shielding performance with appropriate in-wearing instruments due to their minimum thickness. The chemical interaction between Fe 3 O 4 NPs and 3D rPC is examined from chemical composition analysis of Fe 3 O 4 -3D rPC (1 : 2 ratio), which is confirmed by the presence of the Fe-O-C bond in the O 1s spectrum obtained from XPS analysis and subsequent analysis using FESEM images. Furthermore, it is found from N 2 adsorption/desorption analysis that 3D rPC possesses a huge surface area of 787.312 m 2 g -1 and showcases a type-V isotherm (mesoporous and/or microporous) behavior. The dielectric and magnetic losses of Fe 3 O 4 -3D rPC with a 1 : 2 ratio (tan  δ ε r = 1.27 and tan  δ μ r = 5.03) are higher than those of Fe 3 O 4 NPs, 3D rPC and their NCs due to its magnetic and electrical conducting pathways modifying the material's polarization and dipole moment. The lightweight, polymer-free Fe 3 O 4 -3D rPC (1 : 2) NCs with minimum thickness on the order of 0.5 mm exhibited a higher total shielding effectiveness (SE T = 41.285 dB), and it effectively blocked 99.9963% of the transmittance due to electric and magnetic polarization resulting from the presence of a heterogeneous interface surface.