Ultralight pyrolytic carbon foam reinforced with amorphous carbon nanotubes for broadband electromagnetic absorption

For the electromagnetic wave absorbing materials, the extreme value of absorption at a specific frequency is constantly breaking through, but enhancing the absorption properties in the entire band is still a challenge. In this work, a three-dimensional porous pyrolytic carbon (PyC) foam matrix is obtained by template method. Then amorphous carbon nanotubes (CNTs) are in-situ grown on the surface to get ultralight CNTs/PyC foam. The amorphous CNTs are able to distribute uniformly and can be controlled by the catalytic growth time. The interface polarization and conduction loss of the composites can be enhanced by in-situ grown CNTs. When electromagnetic wave enter the internal holes of the material, electromagnetic energy can be completely attenuating under the combined action of polarization, conductivity loss mechanism, and multiple reflections. The density of the ultralight CNTs/PyC foam is merely 22.0 mg·cm^-3, and reflection coefficient is lower than -13.3 dB in the whole X-band (8.2~12.4 GHz), which is better than the conventional standard of effective absorption bandwidth (≤-10 dB). The results provide ideas for researching ultralight and strong electromagnetic wave absorbing materials in X-band.