Synergistic Advancements in Electromagnetic Interference Shielding: Harnessing Fe3O4 Nanoparticles and Biomass-Derived N-Doped Carbon-Layered Structure for Next-Generation Nanocomposites

The study reports on the microwave electromagnetic (EM) shielding performance of Fe3O4 nanoparticles (NPs) and the layered structure of nitrogen-doped sugar cane bagasse (N-SCB) derived from sugarcane waste product. However, the nitrogen-doped SCB is prepared through a high-temperature pyrolysis process under N2 and H2 gases, resulting in a structure that resembles graphene. Three nanocomposites (NCs) are synthesized by varying Fe3O4 NPs and N-SCB ratios to study their impact on electromagnetic interference (EMI) shielding performance, optimizing conductivity, stability, homogeneity, etc. The presence of a strong chemical interaction between Fe3O4 NPs and N-SCB was confirmed through the observation of Fe–O–C bonding in the O 1s spectra obtained through XPS analysis. The chemically incorporated Fe3O4 NPs into the N-SCB layer, resulting in a doped layer with three-dimensional network structures, thereby enhancing the electrical conductivity. Additionally, the superior magnetic saturation value (Ms = 67.63 emu/g) of Fe3O4 NPs was confirmed via VSM analysis, indicating their superparamagnetic nature. Furthermore, the surface area of N-SCB (236.80 m2/g) and the surface decoration of Fe3O4 NPs on N-SCB are examined through BET and HRTEM analyses. Notably, the microwave complex relative permittivity (εr′–jεr″ = 97.98–j58.93) and permeability (μr′–jμr″ = 0.46–j1.08) of the Fe3O4–N-SCB (1:2) ratio were found to be higher than those of the pure material and other different ratio NCs. This was attributed to the homogeneous particulate decoration and reduced particulate agglomeration in this specific NC. Moreover, the enhanced εr′–jεr″ and μr′–jμr″ of the 1:2 ratio material resulted in a high EMI total shielding effectiveness of 48.59 dB at 8 GHz in the X-band region, even with a thickness of only 0.5 mm.