Magnetic carbon nanofibers containing uniformly dispersed Fe/Co/Ni nanoparticles as stable and high-performance electromagnetic wave absorbers

Carbon nanofibers with ferromagnetic metal nanopartictes (CNF-M, M = Fe, Co, and Ni) have been synthesized by carbonizing electrospun polyacrylonitrile nanofibers including metal acetytacetonate in an argon atmosphere, and their phase composition, microstructure, magnetic properties and electromagnetic (EM)-wave absorbability have been studied. The microstructure analysis shows that the in situ formed metal nanopartictes are well distributed along carbon-based nanofibers and encapsulated by ordered graphite layers. The investigation of magnetic properties and EM-wave absorbability reveals that the as-synthesized CNF-M has typical characteristics of ferromagnetic materials and exhibits excellent EM-wave absorption properties (reflection loss exceeding -20 dB) from the C-band to the Ku-band (4-18 GHz) over an absorber thickness of 1.1-5.0 mm due to the efficient complementarities of complex permeability and permittivity resulting from the magnetic metal nanoparticles and lightweight carbon, as well as the particular particle/graphite core/shell microstructures in CNF-M. Moreover, a minimum reflection loss value of -67.5, -63.1, and -61.0 dB is achieved at 16.6, 12.9, and 13.1 GHz with a matching thickness of 1.3, 1.6, and 1.7 mm for CNF-Fe, CNF-Co, and CNF-Ni, respectively. These magnetic carbon nanofibers are attractive candidates for the new type of high performance EM-wave absorbing materials.