Microstructure design of magnetic-dielectric MCHS@Co@CNTs composites with tunable conductive loss for high-performance microwave absorption

Developing the synergistic magnetic-dielectric composites with multiple loss mechanism as excellent microwave absorber is the goal pursued by researchers, but the effective regulation of specific mechanism still remains a challenge. In this work, we fabricated the customized composites of mesoporous carbon hollow sphere (MCHS)@Co@carbon nanotubes (CNTs) for high-performance microwave absorption (MA). First, MCHS with hierarchical porous structure was selected as light dielectric substrate. Then, metal Co nanoparticles were introduced into the pores of MCHS to provide magnetic loss and as catalyst. Last, the CNTs are in-situ grafted on MCHS to serve as electrons transportation channels to reinforce conductive loss. The obtained magnetic-dielectric composites integrated multiple loss mechanism present excellent MA performance with strong absorption intensity of –37.3 dB and wide effective absorption bandwidth of 8.0 GHz under low filling ratio of 20%. Moreover, the conductive loss can be tuned through regulating the length of CNTs. It is confirmed that the appropriate length of CNTs can endow the composites with feasible microwave attenuation ability and impedance matching feature. This work provides a new way to control loss mechanism from microstructure design to optimize MA capability.