Glass Microsphere@NiFe2O4@PANI Core–Shell Composites for Electromagnetic Wave Absorption

Abstract

To meet the demand for high-efficiency electromagnetic wave absorbing materials, this work presents a ternary nanoscale composite with a glass microsphere@NiFe2O4@PANI (GM@NiFe2O4@PANI) core–shell architecture. The fabrication employs a strategy that combines interfacial cooperation with morphological inheritance. XRD and XPS analyses confirmed the formation of spinel nickel ferrite (NiFe2O4) as the dominant phase, with a minor amount of coexisting NiO, and a successful polyaniline (PANI) coating. SEM revealed that NiFe2O4 inherits the nanoflower-like morphology of its NiFe-LDH precursor, with ultrathin nanosheets uniformly anchored on the glass microsphere surfaces. The incorporation of PANI preserves this nanoscale porous structure while introducing additional heterojunction interfaces. The optimized GNFOP-6 composite achieves ideal impedance matching at a thickness of 2.35 mm, delivering an exceptional minimum reflection loss of −68.35 dB and a broad effective absorption bandwidth of 6.40 GHz. The nanoflower-like NiFe2O4 enhances magnetic loss through natural resonance and promotes multiple scattering via its nanoscale porous architecture. Meanwhile, the conductive PANI shell contributes to attenuation through conduction loss and dipole polarization. By synergistically optimizing dielectric and magnetic losses, this nanoscale core–shell design shows strong potential for electromagnetic protection in advanced communication systems and radar stealth.