Ni/CNTs and carbon coating engineering to synergistically optimize the interfacial behaviors of TiO 2 for thermal conductive microwave absorbers

With the coming of 5G era, endowing the microwave absorbers with a light weight and a high thermal conductivity is crucial yet challenging. Combining dielectric/magnetic components with the abundant heterointerfaces has been considered as a promising approach for the development of functional materials with excellent microwave absorption (MA) performances. Herein, we successfully constructed a hierarchical heteronanobrush architecture with carbon-coated TiO2 as a backbone decorated by Ni-catalyzed carbon nanotubes (TiO2@C-Ni/CNTs) for excellent MA and thermal management application, and investigated the influence of the Ni/CNTs content on its MA property. CNTs and the well-distributed Ni nanoparticles on top can promote dielectric behaviors and magnetic performances of composites, which is beneficial to the formation of dielectric and magnetic coupling network. Furthermore, the multiple core-shell structures included in TiO2@C-Ni/CNTs composites have the vast heterogeneous interfaces, which can result in multiple relaxation and effective interfacial polarization. Under the synergic action of the conductive loss, interface polarization, and threedimensional spatial network structure, as-synthesized TiO2@C-Ni/CNTs nanobrushes possess superior MA performances with the minimum reflection loss (RL) of -32.3 dB at 17.3 GHz with a thickness of 1.6 mm and the broadest effective absorption bandwidth (EAB) of 5.5 GHz with a thickness of 1.8 mm. Furthermore, the thermal conductivities and diffusivities of the TiO2@C-Ni/CNTs/nature rubber hybrids are also effectively enhanced. This work provides an idea to design magnetic-dielectric composite nanostructures for MA and thermal management materials.