Ultra‐Low Loading of Ultra‐Small Fe3O4 Nanoparticles on Nonmodified CNTs to Improve Green EMI Shielding Capability of Rubber Composites

Abstract From a material design perspective, the incorporation of Fe 3 O 4 @carbon nanotube (Fe 3 O 4 @CNT) hybrids is an effective approach for reconciling the contradictions of high shielding and low reflection coefficients, enabling the fabrication of green shielding materials and reducing the secondary electromagnetic wave pollution. However, the installation of Fe 3 O 4 nanoparticles on nonmodified and nondestructive CNT walls remains a formidable challenge. Herein, a novel strategy for fabricating the above‐mentioned Fe 3 O 4 @CNTs and subsequently assembling segregated Fe 3 O 4 @CNT networks in natural rubber (NR) matrices is proposed. The advanced and unique structure, magnetism, and lossless conductivity endow the as‐obtained Fe 3 O 4 @CNT/NR with a shielding effectiveness (SE) of 63.8 dB and a low reflection coefficient of 0.24, which indicates a prominent green‐shielding capability that surpasses those of previously reported green‐shielding materials. Moreover, the specific SE reaches 531 dB cm −1 , exceeding that of those of previously reported carbon/polymer composites. Meanwhile, the outstanding conductivity enables the composite to reach a saturation temperature of ≈95 °C at a driving voltage of 1.5 V with long‐term stability. Therefore, the as‐fabricated Fe 3 O 4 @CNT/rubber composites represent an important development in green‐shielding materials that are applied in cold environment.