Renewable, self-supporting bamboo-based composites for electromagnetic absorption and electrothermal management

Electromagnetic wave pollution has always been a problem that affects human health and the operation of precision instruments. The recent research focus has been on the preparation of effective electromagnetic wave absorbers using biomass materials. In this study, natural bamboo was utilized as the raw material, and an innovative strategy was established by combining delignification pretreatment with iron salt impregnation, followed by in-situ pyrolysis. Through this process, high-performance magnetic bamboo-based composites (BBCs) were successfully fabricated. The delignification process played a crucial role in modifying the hierarchical pore architecture of bamboo, thereby promoting more uniform iron salt infiltration and enhanced dispersion of magnetic nanoparticles during carbonization. Owing to these structural improvements, the BBC-1000 sample demonstrated outstanding electromagnetic wave absorption capability: at a thickness of just 2.1 mm, it achieved a minimum reflection loss of -57.6 dB and a broad effective absorption bandwidth (RL ≤ -10 dB) reaching 7.8 GHz. This study highlights that delignification not only improves impedance matching but also facilitates the formation of a three-dimensional conductive framework with well-distributed magnetic loss sites, resulting in a synergistic enhancement of both dielectric and magnetic losses. Moreover, CST simulations confirmed that BBC-1000 offers substantial radar wave attenuation across different incident angles when used as a coating material. At 5 V, the temperature of BBC-1000 rapidly increases to 166 °C.