In-situ growth of magnetic nanoparticles on honeycomb-like porous carbon nanofibers as lightweight and efficient microwave absorbers

To achieve the goal of both lightweight and strong absorption, tailoring the microstructure and components of microwave absorber had been regarded as a promising method. Herein, in-situ growth of magnetic Ni nanoparticles on honeycomb-like porous carbon nanofibers were prepared by electro-blowing spinning and subsequent high-temperature pyrolysis technique. The honeycomb-like porous structure of carbon nanofibers was formed by the decomposition of pore forming agent PTFE nanoparticles during carbonization process, and the effects of PTFE content on the specific surface area and pore size distribution were systematically studied. Simultaneously, the magnetic Ni nanoparticles were in-situ formed and homogenously dispersed in the fiber skeleton. The obtained fibers were connected into a three-dimensional (3D) interconnected macroscopic network, which could form an electrically conductive network to enhance the conductive loss, and induce multiple reflecting and scattering to consume electromagnetic waves. The honeycomb-like porous structure with large specific surface area could shorten the impedance gap with free space and endow the absorber with lightweight feature. In addition, the in-situ growth magnetic Ni nanoparticles introduced additional magnetic loss, which was also benefit to improve the impedance matching. Moreover, the formed heterojunctions at the interface of magnetic Ni nanoparticles and carbon nanofibers triggered intensive interfacial polarization. Under the synergistic effect of magnetic-dielectric loss, appropriate impedance matching, strong interfacial polarization and multiple reflecting and scattering, the optimal sample of Ni/PCNF-2 presented an excellent microwave absorption performance with the minimum RL of -40.48 dB at 1.5 mm thickness, and the effective absorption bandwidth reached to 4.0 GHz.