Superparamagnetic Fe₃O₄ nanoparticles on graphene-polyaniline: Synthesis, characterization and their excellent electromagnetic absorption properties

The ternary nanocomposites of graphene-polyaniline-Fe₃O ₄ (GN-PANI-Fe₃O₄) have been prepared via a two-step method, the chemical oxidative polymerization of aniline and subsequent in situ generation of superparamagnetic Fe₃O₄ nanoparticles by a co-precipitation method. The obtained ternary nanocomposites were characterized by XRD, FETEM, Raman spectroscopy, XPS, VSM and TG analysis. TEM studies reveal that Fe₃O₄ nanoparticles with the size in the range of 5-20 nm are uniformly dispersed on the surfaces of GN-PANI. The absorption mechanism of the ternary nanocomposites was also discussed. The investigation of the electromagnetic absorbability reveals that GN-PANI-Fe ₃O₄ exhibits enhanced electromagnetic absorption properties compared to GN-PANI and GN-Fe₃O₄, which is mainly ascribed to the improved impedance matching, the geometric effect and the enhanced interfacial effects. The maximum reflection loss of the ternary nanocomposites is up to -43.9 dB at 11.4 GHz with absorber thickness of 2.5 mm. When the matching thicknesses vary from 2 to 4 mm, all the maximum reflection loss values are less than -24.2 dB. Our findings pave a different way to design excellent electromagnetic absorption materials.