The electromagnetic wave (EMW) absorbing materials used in harsh working environments are susceptible to thermal degradation and dielectric constant drift caused by humidity fluctuation, which severely restricts their practical applicable in aerospace, marine engineering and advanced electronics. Herein, a hierarchical nanoarchitecture consisting of silica-coated carbon nanofibers uniformly anchored with NiFe₂O₄ nanosheets (denoted as CFNOS) is fabricated via a combined electrospinning-hydrothermal-carbonization route. This ternary structural design circumvents the inherent drawbacks of pristine carbon nanofibers through synergistic dielectric and magnetic loss: NiFe₂O₄ introduces dominant magnetic loss, while the outer silica shell strengthens interfacial polarization to realize efficient EMW dissipation. The optimized CFNOS-2 delivers a minimum reflection loss (RL_min) of -59.10 dB at 1.68 mm, together with an effective absorption bandwidth (EAB) of 5.04 GHz at 1.60 mm, exceeding most previously reported carbon-based absorbers. Benefiting from the protective silica layer, CFNOS-2 possesses robust environmental adaptability, featuring a water contact angle of 139.1°, residual mass exceeding 80% upon heating to 800°C, as well as favorable thermal insulation and infrared stealth performance (surface temperature maintained at 120°C over 45min). This work provides a facile structural strategy toward high-performance EMW absorbers applicable for extreme environments, paving a feasible route for next-generation stealth devices and high-density electronic packaging.

The regulation of pore structures plays a crucial role in optimizing the electromagnetic wave absorption performance of porous materials by facilitating multiple reflection/scattering effects and improving impedance matching. Among lightweight absorbers, morphable biomass-derived porous carbon has emerged as a research hotspot due to its shape-tunable morphology, adjustable porosity, low density, cost-effectiveness, and facile fabrication. In this study, tofu was employed as a precursor to prepare sponge-like tofu and porous carbon (PCM) with varying pore sizes and densities by controlling compression pressure. The results demonstrate that moderate compression pressure induces an optimized pore architecture, which effectively enhances conductive loss, polarization loss, and synergistic multiple reflection/scattering mechanisms. The optimized PCM-4K sample achieves a minimum reflection loss (RL_min) of −41.14 dB at a matching thickness of 1.3 mm, along with the broadest effective absorption bandwidth (EAB) of 4.08 GHz at 1.4 mm. This work not only presents a novel biomass-derived carbon synthesis strategy for precise pore structure engineering but also elucidates the porous-structure-mediated absorption mechanism, providing valuable insights for the design and optimization of next-generation lightweight electromagnetic wave absorbers.