Evaluating the microwave absorbing performance of polymer-free thin Fe3O4-MWCNT NCs in X-band region

In the past decade, hierarchical structure formation of magnetic (Fe3O4) and carbon based electrically conducting nanocomposites (NCs) has been widely used in microwave shielding applications due to the presence of lightweight, huge surface area, heterogenous interface surface etc. Current research is focused on reducing the thickness of the shielding material without compromising its performance. Herein, the fabrication of a 500 mu m thick, polymer-free, stand-alone electromagnetic interference (EMI) shielding pellets of Fe3O4 - amine functionalized multiwalled carbon nanotube (MWCNT) NCs is reported with an average shielding efficiency of 60.7 dB for 8 to 12 GHz. The amine-functionalized MWCNT has superior electric conductivity due to the presence of reduced surface oxidation groups and superior charge carrying by free electrons in the amine groups. The structural and magnetic properties of all the materials were confirmed by XRD, Raman, FESEM, HRTEM, VSM and VNA techniques. The chemical interaction of Fe3O4-MWCNT was confirmed by the presence of the Fe-O-C bond from the O 1s spectrum from XPS analysis. The Fe3O4 nanoparticles (NPs) are homogeneously incorporated on the MWCNT surface, forming composite structures, which improve interface polarization, electron charge carrying, and impedance matching due to the presence of chemical interaction.