Triple-functional FeCl3-crosslinked carbon aerogel: synchronous strengthening, ultra-broadband wave absorption, and thermal insulation

Electromagnetic pollution poses growing threats to electronic equipment, data security, and human health, yet developing lightweight absorbers that simultaneously achieve high mechanical strength, broadband absorption, and thermal insulation remains challenging. To address this gap, we report a triple-functional FeCl 3 -crosslinked carbon aerogel (CA-Fe) fabricated by integrating hydrazine-modified polyacrylonitrile (PAN) nanofibers into a chitosan matrix, followed by freeze-drying and carbonization. Fe 3 ⁺ serves dual roles as crosslinker and graphitization catalyst, reducing the ID/IG ratio from 2.75 (in Fe-free CA) to 2.6 and enhancing electrical conductivity. The resulting CA‐Fe achieves a compressive strength of 0.62 MPa—a 121% increase over CA—and outstanding electromagnetic wave absorption with a minimum reflection loss (RLmin) of − 61.2 dB at 3.0 mm thickness and an effective absorption bandwidth (EAB) of 5.8 GHz. These properties stem from optimized impedance matching (Z values in the 0.8–1.2 range) facilitated by the introduction of magnetic loss, synergistic conductive networks from catalytic graphitization, and multi-polarization losses induced by structural defects and Fe/N-doping. Moreover, CA-Fe exhibits low thermal conductivity (0.049 W m −1  K −1 at 25 °C), demonstrating its potential for thermal management in aerospace electronics, stealth technology, and next-generation communication devices. This work provides a viable strategy for designing lightweight, robust, and high-efficiency multifunctional EMW absorbers.