Microwave absorption properties of Co/C and Ni/C composite nanofibers prepared by electrospinning

Carbon nanofibers with Co, Ni nanoparticle were synthesized by a two-step process involving electrospinning and heat treatment. Their phase composition, microstructure, elemental composition and electromagnetic characteristics were characterized using x-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and vector network analyzer (VNA). The microwave absorption performance of these carbon nanofibers was also studied. The results indicate that these composite nanofibers are intact and consist of amorphous carbon and face-centered cubic structured magnetic metals. The resultant metal nanoparticles are uniformly dispersed along carbon-based nanofibers which enhance the synergistic and interfacial effects between magnetic loss and dielectric loss. When the thicknesses of the absorbers are 1.5 mm, the absorption bandwidths (RL <= -10 dB) are approximately 4 GHz and 2.5 GHz for the Co/C, Ni/C composite nanofibers, respectively, which are obviously superior to pure carbon nanofibers. Co/C composite nanofibers exhibit a wider absorption band range and stronger microwave absorption intensity compared to Ni/C composite nanofibers, attributed to their excellent electromagnetic impedance matching and attenuation characteristics. This indicates that the Co/C composite nanofibers are promising candidates for novel microwave absorbing materials.