Fe3C nanocrystals encapsulated in N-doped carbon nanofibers as high-efficient microwave absorbers with superior oxidation/corrosion resistance.

In addition to the demand of thin, lightweight, broadband and high-efficient characteristics, exploring microwave absorbents with superior resistance to oxidation and corrosion is urgently need for practical applications. Herein, carbon nanofibers embedded by α-Fe 2 O 3 , Fe or Fe 3 C nanocrystals are prepared through electrospinning technique followed by carbonization in different atmospheres. The one-dimensional structures can intertwine into three-dimensional conductive network, which is favored for energy dissipation. The Fe 3 C/N-doped carbon nanofibers show boosting microwave absorption properties compared to the bare carbon, α-Fe 2 O 3 /C and Fe/C nanofibers. The Fe 3 C/N-doped carbon nanofibers show an optimal reflection loss of −57.9 dB at 5.8 GHz with a thickness of 4.1 mm. Meanwhile, a reflection loss of −54.5 dB can be achieved at 17.8 GHz, when the absorber thickness is only 1.5 mm. The superior microwave absorption properties are attributed to the dipole polarization, interfacial polarization and ferromagnetic resonance, induced by the synergistic effect of Fe 3 C nanocrystals and carbon nanofibers. Moreover, acid-soaking and air-annealing treatments reveal that the Fe 3 C/N-doped carbon nanofibers show remarkable corrosion and oxidation resistance. This work suggests that encapsulating magnetic nanocrystals in dielectric carbon-based materials is an efficient strategy to construct high-efficient lightweight microwave absorbents with oxidation/corrosion resistance. [Display omitted] • Fe 3 C embedded in C nanofibers are fabricated by electrospinning-carbonization route. • Fe 3 C/N–C nanofibers show optimal RL values of −54.5 dB with a thickness of 1.5 mm. • The Fe 3 C/N–C nanofibers show superior resistance to corrosion and oxidation. [ABSTRACT FROM AUTHOR]