Honeycomb-reinforced gradient carbon nanotube/aramid nanofiber aerogel metamaterial with excellent electromagnetic wave absorption and load-bearing performance

Porous aerogels have emerged as promising candidates for lightweight electromagnetic wave absorption (EMWA) materials, yet their practical performance and engineering deployment are severely constrained by three long-standing bottlenecks: the inherent trade-off between interfacial impedance matching and internal electromagnetic dissipation, the strong angular dependence of EMWA performance, and the insufficient mechanical load-bearing capability. Herein, we developed a novel dot-matrix cold-source ice-templating technique in conjunction with honeycomb skeleton reinforcement to fabricate waxberry-like gradient porous aerogel/honeycomb metamaterials (WGPA/H). The influences of critical structural parameters, including aerogel pore structure and honeycomb cell size, were systematically investigated. The optimal WGPA/H delivers an exceptional minimum reflection loss (RL_min) of −78.5 dB and an ultrabroad effective absorption bandwidth (EAB) of 12.4 GHz. More notably, WGPA/H retains a stable ultrabroad EAB at oblique incidence angles from 5° to 60°, demonstrating excellent angle-insensitive EMWA behavior. This outstanding comprehensive EMWA performance is attributed to the synergistic coupling effect between the unique waxberry-like gradient porous structure and the periodic honeycomb array. Furthermore, WGPA/H integrates high thermostability and a compressive strength up to 4.1 MPa, fully satisfying the service requirements of complex high-temperature and high-loading scenarios. The resultant WGPA/H well preserves the intrinsic lightweight characteristic of aerogels, breaks the trade-off between impedance matching and electromagnetic loss, realizes wide-angle EMWA stability, and simultaneously achieves significantly enhanced mechanical load-bearing performance. This work provides a new structural design strategy for multifunctional EMWA devices, facilitating their practical engineering applications.