Morphology Design of Co-electrospinning MnO-VN/C Nanofibers for Enhancing the Microwave Absorption Performances.

To enhance microwave loss abilities, constructing composites with one-dimensional (1D) structure is an excellent scheme. In this work, a high-efficiency microwave absorber of MnO nanograins decorated vanadium nitride/carbon nanofibers (MnO-VN/C NFs) was successfully prepared for the first time via co-electrospinning technology and subsequent nitriding treatment. Studying in detail the specific relationship between nitriding time and the morphology of the as-prepared NFs, the precipitations of MnO nanoparticles with tailored structures were attached on the surface of VN/C NFs to optimize their electromagnetic parameters. When the nitriding time was 2.0 h at 600 °C, the MnO-VN/C NFs displayed good microwave absorption performances: the minimum reflection loss (RL) value was -63.2 dB at 8.8 GHz, and the bandwidth of RL < -10 dB was up to 6.4 GHz from 11.6 to 18 GHz at the thickness of 2.8 mm. Meanwhile, the absorption bandwidth (RL< -10 dB) could cover the whole X and Ku band by adjusting the thickness, respectively. The outstanding performances could be attributed to the good impedance matching and various loss pathways including conductive loss and interfacial and dipole polarizations. In these regards, MnO-VN/C NFs are likely to be utilized as a high-efficiency microwave absorber. And the strategy in this work can provide great help to design other 1D structural microwave absorbers with a broader absorbing band.