Nest-Like Carbon Nanotube Network Derived from Fly Ash Cenosphere with Enhanced Microwave Absorption Performance

Carbon nanotubes (CNTs) are widely utilized as microwave absorption (MA) materials due to their low density and high loss capacity. However, the poor impedance match and single mechanism of CNTs limit the further development of CNT-based high-performance MA materials. Herein, inspired by the bird nest frame structure, we designed a nest-like CNT network derived from fly ash cenospheres. The fly ash cenosphere@CNTs depict good MA performances with an effective absorption band of 6.96 GHz and corresponding minimum reflection loss of −61.16 dB. The excellent MA properties may be attributed to the conduction loss, polarization loss, and magnetic loss resulting from the synergistic effect of their hollow heterogeneous, nest-like network structure, and magnetism/electricity components. The simulation of the far-field radar cross section further verifies the reliability of the fly ash cenosphere@CNTs in actual microwave environments. In this work, an approach is proposed to improve the MA properties of carbon-based materials.