Temperature‐Driven EMW Absorption and EMI Shielding via 3D Conductive and Magnetic–Dielectric Networks in PVDF/NiFe2O4@CNTs

The rapid advancement of electronic and communication technologies has led to a significant increase in electromagnetic (EM) pollution, necessitating the development of efficient electromagnetic interference (EMI) shielding materials to mitigate adverse effects on both human health and electronic systems. In this study, a series of ternary nanocomposites comprising NiFe 2 O 4 @carbon nanotubes (NFO@CNTs) was synthesized via the solvothermal method. Subsequently, NiFe 2 O 4 @CNTs were incorporated into polyvinylidene fluoride (PVDF) to fabricate PVDF/NiFe 2 O 4 @CNTs composites. The CNTs content was varied from 1 to 5 wt.% w.r.t NiFe 2 O 4 to optimize electrical conductivity and impedance matching, while tuning the synthesis temperature. X‐ray diffraction (XRD) and Raman analysis confirmed the successful formation of NiFe 2 O 4 @CNTs composites, while transmission electron microscopy (TEM) images revealed the uniform functionalization of CNTs, the anchoring of NiFe 2 O 4 nanoparticles on CNTs walls, and the formation of a 3D conductive network. Ternary composite NTC10(5) exhibited maximum EMI shielding effectiveness (SE T ) of 16.20 dB, equivalent to 97.61% attenuation, which further increased to 22 dB (> 99% attenuation) upon optimizing the processing temperature to 100°C. Additionally, electromagnetic wave (EMW) absorption performance was evaluated by introducing a metallic backing layer. The NTC7(1) sample demonstrated the highest reflection loss (RL min ) of −30 dB, corresponding to greater than 99.9% EMW absorption.