Mechanically Robust Fe₇S₈/C@PVA@ANF Aerogels with Superior Microwave Absorption and Infrared Stealth Performance

Carbon aerogel materials exhibit unique advantages in electromagnetic microwave absorption (EMA) applications due to their exceptional low density, tailorable three-dimensional porous architecture, and remarkable dielectric loss capabilities. However, developing carbon aerogel materials with robust mechanical strength and superior microwave absorption performance remains a significant challenge. Herein, this study employs a simple mechanical foaming and freeze-drying process to successfully construct mechanically robust Fe7S8/C@PVA@ANF aerogel composite materials, which feature a surface macroporous skin and internally interconnected honeycomb porous structure. Benefiting from the reinforced aramid nanofiber (ANF) skeleton, the bonding reinforcement effect of poly(vinyl alcohol) (PVA), and the unique one-dimensional (1D) Fe7S8/C nanorod building blocks, the fabricated aerogels demonstrate exceptional mechanical properties, delivering an outstanding elastic recovery rate exceeding 90% after 100 compression cycles at 40% strain. Additionally, it achieved an ultralow density of 0.02 g/cm3. Leveraging the biomass sodium alginate-derived Fe7S8/C nanorods and the abundant porosity of the aerogels, the composite materials enable the regulation and optimization of impedance matching. Furthermore, the internally interconnected honeycomb porous structure establishes a three-dimensional (3D) conductive network, facilitating multiple reflections and the scattering of electromagnetic waves. The optimized aerogels exhibit remarkable EMA performance, achieving a minimum reflection loss (RLmin) of −42.68 dB at 10.05 GHz and an effective absorption bandwidth (EAB) of 7.35 GHz at a thickness of 3.5 mm. Concurrently, the optimized aerogels demonstrate excellent infrared (IR) stealth capability, with their surface temperature rising merely from 24.3 to 26.1 °C after 60 min of IR irradiation on an 80 °C heating platform. Such well-designed Fe7S8/C@PVA@ANF aerogels demonstrate significant potential in radar and infrared stealth applications for personnel protection and weapon systems.