Heterogeneous and hierarchical ni/C/SiO2 composite with tunable electromagnetic wave absorption

Structure design, conductivity regulation and electromagnetic matching are important to optimize the electromagnetic wave (EMW) absorbing properties. Therefore, exploring a strategy which kill these three birds with one stone is extraordinary. In this work, the heterogeneous and hierarchical Ni/C/SiO2 composite with tunable EMW absorption properties was synthesized through a simple calcination process. The introduction of SiO2 and Ni prompted a relatively large hole generated in the center of carbon fiber and formed hierarchical porous structure with the circumambient small holes which extended the propagation path of EMW, realized multiple reflection and scattering and endowed sufficient interfacial polarization. Meanwhile, the SiO2 and Ni nanoparticles played an important role in conductivity regulation and electromagnetic matching. Owing to the ingenious hierarchical porous structure and synergistic effect of multiple loss mechanisms, the Ni/C/SiO2-0.5 exhibited the optimal absorption properties with the maximum reflection loss (RL) of -47.65 dB at 3.1 mm with the filler content of 10 wt%. This research would provide a novel strategy for the exploitation route of the EMW absorbing materials.