Bionic hierarchical porous carbon fibers with honeycomb-like skeleton and surface cactus-spine-like hollow nanotubes for high-performance electromagnetic wave absorption

To address the escalating electromagnetic wave (EMW) pollution, the development of advanced absorbers with lightweight property, broad bandwidth, and strong attenuation capabilities is urgently required. This study fabricates bionic hierarchical porous carbon fiber (HPCF) featuring a honeycomb-like skeleton and surface cactus-spine-like hollow nanotubes for high-performance electromagnetic wave absorption (EMWA). The HPCF is synthesized via an integrated process combining electro-blowing spinning, hydrothermal reaction, and carbonization technique. The honeycomb-like skeleton of the porous carbon fiber forms an electrically conductive network, enhancing conductive loss. The surface cactus-spine-like hollow nanotubes create abundant interfaces and sharp conductive tips, promoting interfacial and dipole polarization loss. The synergistic honeycomb-like/cactus-spine-like structure offers a large specific surface area and high porosity, which not only facilitates multiple reflection/scattering to dissipate EMW energy, but also traps high volume fraction of air to improve impedance matching. Notably, at a low filler loading of 15 wt% and a thin thickness of 1.5 mm, the optimized HPCF -2 achieves an ultra-strong reflection loss (RL) of −55.35 dB, and an effective absorption bandwidth (EAB, RL < −10 dB) of 3.80 GHz. This work presents a bionic strategy for developing lightweight, broadband, and high-efficiency absorbers for next-generation stealth and shielding applications.