Fe3C-Coated Nitrogen-Doped Carbon Nanotube/Cattail-Derived Carbon Microtube Composites for Efficient Microwave Absorption
Carbon materials suffer from limited dielectric loss, resulting in poor impedance matching and inadequate microwave attenuation. To address this, hierarchical structures with synergistic loss mechanisms are sought. Here, biomass cattail serves as a sustainable precursor for nitrogen-doped carbon nanotube arrays decorated with Fe3C nanoparticles via chemical vapor deposition, yielding Fe3C@NCNTs/CMTs composites. The crystallinity, tuned by calcination temperature, critically influences microwave absorption. At 800 °C, the composite achieves a minimum reflection loss of –35.8 dB and an effective absorption bandwidth of 7.02 GHz at a thickness of only 1.7 mm, with an ultralow filler loading of 10 wt%, covering the entire Ku band and part of the X band. This performance stems from enhanced magnetic loss and multiple dielectric polarization mechanisms. The study demonstrates a promising strategy for designing biomass-derived carbon-based broadband microwave absorbers.