Multiple polarization loss and permittivity adjusting of halloysite/BN Co-doped carbon/cobalt composites

Halloysite hybridized B-N co-doped C/Co composites (HNT/BNC/Co) for microwave absorption were prepared via a one-step pyrolysis method. The results indicate that the samples are consisted of halloysite nanotubes (HNT), cobalt nanoparticles and B-N co-doped carbon nanotubes (CNTs). Benefiting from unique hollow tubular structure and the polarization between multiple components, the 0.15HNT/BNC/Co composites with 40 wt% in wax matrix exhibit remarkable microwave absorption properties. A maximum reflection loss up to -40.86 dB with the thickness 1.51 mm at 17.12 GHz, and an effective absorption bandwidth (<-10 dB) up to 4.8 GHz (in the range 12.16-16.96 GHz) can be achieved in this sample. The unique hollow tubular morphology of halloysite and CNTs make it possible to obtain suitable complex permittivity when the sample doping content is 40 wt.%. Furthermore, it was found that the halloysite can be used to adjust complex permittivity of the composites, which were derived from the electromagnetic parameters of composites with different contents of halloysite and the changed doping amounts in paraffin-wax hybrids. This study can provide a new strategy for designing novel carbon and halloysite hybridized microwave absorption materials.