Ni/CNTs and carbon coating engineering to synergistically optimize the interfacial behaviors of TiO2 for thermal conductive microwave absorbers

Abstract

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 hetero-nanobrush 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 three-dimensional 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.