High-performance EMI shielding effectiveness of Fe3O4-3D rPC nanocomposites: a systematic optimization in the X-band region

In this work, the microwave absorption (MWA) performance of a Fe<INF>3</INF>O<INF>4</INF>-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<INF>3</INF>O<INF>4</INF> 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<INF>3</INF>O<INF>4</INF> NPs and 3D rPC is examined from chemical composition analysis of Fe<INF>3</INF>O<INF>4</INF>-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<INF>2</INF> adsorption/desorption analysis that 3D rPC possesses a huge surface area of 787.312 m2 g-1 and showcases a type-V isotherm (mesoporous and/or microporous) behavior. The dielectric and magnetic losses of Fe<INF>3</INF>O<INF>4</INF>-3D rPC with a 1 : 2 ratio (tan delta<INF>epsilon<INF>r</INF></INF> = 1.27 and tan delta<INF>mu<INF>r</INF></INF> = 5.03) are higher than those of Fe<INF>3</INF>O<INF>4</INF> 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<INF>3</INF>O<INF>4</INF>-3D rPC (1 : 2) NCs with minimum thickness on the order of 0.5 mm exhibited a higher total shielding effectiveness (SE<INF>T</INF> = 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.