Lightweight and robust aerogel assembling with aramid nanofibers and biomass-derived magnetic carbon nanoparticles toward advanced microwave absorption and infrared stealth

Carbon aerogel exhibits unique advantages in microwave absorption and infrared stealth applications owing to its ultralow density, high porosity, and continuous three-dimensional conductive networks. Nevertheless, developing carbon aerogel with excellent mechanical robustness to meet the practical application demands remains a significant challenge. Herein, a lightweight and robust aerogel assembling with biomass-derived magnetic nickel/carbon (Ni/C) nanoparticles and aramid nanofibers (ANF) is successfully constructed. The magnetic Ni/C nanoparticles are synthesized via an innovative wet-spraying technique that fully exploits the strong chelation capability of biomass sodium alginate toward metallic nickel ions. After high-temperature carbonization, this process yields magnetic Ni/C nanoparticles with high specific surface area, and offers advantages of simple processing procedures and high yield. Concurrently, the ANF is fabricated by a scalable top-down deprotonation approach, acting as a supportive skeleton to ensure structural integrity and mechanical robustness. The optimized aerogel delivers a unique lamellar network architecture with an ultra-low density of 0.0168 g/cm³ and outstanding elastic recovery exceeding 95 % after 100 cycles at 40 % strain. Consequently, the optimized aerogel delivers remarkable electromagnetic microwave absorption (EMA) performance, achieving a minimum reflection loss (RL_min) of −49.497 dB at 14.87 GHz, and an effective absorption bandwidth (EAB) of 5.41 GHz at a thickness of 2.0 mm. Simultaneously, the optimized aerogel exhibits excellent infrared (IR) stealth capability. After being exposed to IR radiation for 60 min on a heating platform at 80 ℃, the surface temperature of the optimized aerogel only rise from 25.3 ℃ to 26.9 ℃. This study provides a strategic paradigm for designing aerogel material with balanced mechanical properties and multi-functional performance.