Self-Sensing NiFe@N-doped Carbon Aerogel: Integrating Excellent Radar Stealth, Inherent Structural Health Monitoring, Thermal Management, and Flame Retardancy

Abstract Biomass carbon-based aerogels derived from collagen protofibrils are gaining considerable attention in electromagnetic protection. However, achieving a well-designed microstructure, optimized magnetic and dielectric loss components, and integrated multifunctionality within a single material system remains a significant challenge. Herein, a three-dimensional (3D) hierarchically biomimetic honeycomb-like porous magnetic NiFe@N-doped carbon aerogel (NFNCA) is obtained via a simple strategy involving in situ growth, freeze-drying, and pyrolysis carbonization. Driven by the synergy of a 3D conductive networking structure, magnetic and dielectric multi-components, numerous heterogeneous interfaces, and diverse loss pathways, the optimized NFNCA exhibits exceptional electromagnetic wave attenuation capability, evidenced by a minimum reflection loss ( R L ) of −53.49 dB at 1.93 mm and an effective absorption bandwidth of 6.24 GHz (11.76–18.00 GHz). Furthermore, the exceptional radar stealth, infrared thermal stealth, thermal management, and flame retardancy characteristics of NFNCA render it a promising candidate for multiple applications in demanding environments. Interestingly, the 3D cross-linked conductive network of NFNCA can serve as strain sensors to detect changes in the internal structure of carbon aerogels. Hence, this work provides a feasible design strategy for developing lightweight, high-efficiency, and multifunctional biomass-based carbon aerogel electromagnetic wave absorbing materials for various application scenarios.