Structural Engineering of Trifunctional Carbon Micro Cages for Efficient Electromagnetic Wave Absorption

With the growing demand for electromagnetic protection and stealth in modern technologies, carbon nanotubes (CNTs) have emerged as a promising research hotspot in electromagnetic wave absorption owing to their high conductivity, lightweight, and large specific surface area. However, single-component CNTs suffer from an impedance mismatch. To address this limitation, we used magnetic fly ash (MFA) as a sacrificial template to grow carbon micro cages, leveraging its abundant iron content to catalyze CNT growth. The resulting carbon micro cage structure, composed of CNTs and carbon nanowires, yielded an optimized material with a thickness of 2.4 mm, achieving an exceptional minimum reflection loss of -53.38 dB and a broad effective absorption bandwidth of 6.32 GHz (11.52-17.84 GHz). The presence of abundant bamboo nodes introduced numerous polarization-attenuation sites, exemplifying the core strategies of component diversification and structural heterogeneity in the design of wave-absorbing materials. This study offers a scalable approach for converting high-value solid waste into lightweight, broadband wave-absorbing materials. In addition, the waterproof and flame-retardant properties of the carbon micro cage material underscore its strong potential for applications in electromagnetic stealth and protection.