Micronano synergistic design constructs sea-urchin-like hollow SiO₂ internal filled conductive network structure for electromagnetic wave absorption

Carbon nanotubes (CNTs), functioning as wave-absorbing materials, see their wave-absorbing capability diminish owing to poor impedance matching and the skin effect. To address this issue, this study innovatively adopts a bionic design and prepares CNT@SiO₂ composites (CSC) with a sea urchin-like core-shell structure through the combined technology of phase separation emulsification and in-situ sintering. It is noteworthy that the SiO₂ outer shell of CSC and the embedded CNTs form an impedance system with nano-micro composite scales, which not only solves the problem of electromagnetic wave reflection by traditional CNTs but also strengthens the interfacial polarization and dipole polarization effects through the multi-level conductive networks and numerous heterogeneous interfaces constructed by CNTs inside and outside the shell layer, thus realizing the synergistic optimization of loss capacity and matching performance. Benefiting from the synergistic coupling of structural design and compositional regulation, the optimized sample achieves a minimum reflection loss of −58.72 dB at 9.68 GHz and an effective absorption bandwidth of 5.12 GHz at a thickness of 2 mm. This work offers a novel paradigm for the rational design of carbon-based absorbers, integrating bio-inspired architecture and multi-scale loss mechanisms to advance the development of next-generation high-performance electromagnetic wave absorbing materials.