Structural examination and magnetic-microwave absorption properties of Fe₃O₄NPs/rGO composites derived from natural ironsand and coconut shell

This study shows a green method for making Fe₃O₄NPs/rGO nanocomposites using iron sand, a natural material from Indonesia, and biomass from coconut shells. X-ray diffraction (XRD) examination confirmed the effective preparation of the magnetite phase and Fe₃O₄NPs/rGO nanocomposites. The structural integrity of both Fe₃O₄ and rGO was maintained in the composite, as indicated by the characteristic absorbance bands in the FTIR spectra and the well-defined interface observed in the HRTEM images. Incorporating rGO reduced magnetic saturation and initial magnetic susceptibility while increasing the composite coercivity, remanence, and magnetic domain size. A microwave absorption peak was detected at approximately 10.55 GHz, indicating enhanced and tunable electromagnetic wave absorption in the Fe₃O₄NPs/rGO system. The synergistic integration of Fe₃O₄ as the magnetic component and rGO as the dielectric component offers the advantage of simultaneously modulating magnetic dipole alignment and electric dipole polarization, making the composite suitable for targeted electromagnetic applications.