Bamboo-like Carbon Nanotubes Assisted Assembly of Magnetic-Dielectric Aerogels to Enhance Microwave Attenuation

Carbon aerogels have revolutionized the design of advanced electromagnetic wave absorbers by offering low density, multi-functionality, and versatility. However, traditional carbon aerogels face limitation due to their high electrical conductivity and reliance on single loss mechanism, which hinders their widespread applications. To overcome these challenges, a series of multilayered hierarchical CoNi/bamboo-like carbon nanotubes (BCNTs)/carbon nanofiber (CNFs) aerogels are prepared using directional freeze-drying, hydrothermal methods, and catalytic chemical vapor deposition. The effects of layer spacing and thermal growth on the microwave absorption properties of the hybrids are investigated by varying the content of aramid nanofibers and growth temperature. The synergistic effect of dielectric and magnetic loss optimizes the electromagnetic parameters and impedance matching of the samples, which obtains an optimal minimum reflection loss of −80.30 dB at only 2.07 mm. Furthermore, the composite aerogel demonstrates an ultra-wide effective absorption bandwidth of 6.60 GHz at 2.28 mm. The practical application capabilities of the samples are evaluated through theoretical analysis. Besides, the as-prepared aerogels exhibit excellent thermal insulation properties and the ability to adsorb light oils. This study presents an attractive strategy for fabricating CoNi/BCNTs-modified carbon aerogel absorbers, which hold great promise for applications in electromagnetic protection and thermal management devices.