Structural and Carbonized Design of 1D FeNi/C Nanofibers with Conductive Network to Optimize Electromagnetic Parameters and Absorption Abilities

The optimized electromagnetic (EM) parameters are highly indispensable for outstanding microwave absorbers. Generally speaking, it is very necessary to suitably improve permittivity and permeability of the materials. The combination of magnetic/dielectric materials is a good choice. Herein, the irregular shaped FeNi/C composites were synthesized in N2 atmosphere with unsatisfied EM parameters. To further optimize EM parameters and enhance microwave absorption abilities, constructing one-dimensional (1D) structure is also an excellent scheme. 1D FeNi/C nanofibers were successfully obtained by electrospinning technology combined with heat treatment. Enhanced microwave absorption abilities can be fulfilled by conductive network structure, better dielectric loss, and stronger interface polarization intensity. Moreover, carbonized time toward nanofibers plays a key role in microwave absorption, which could influence complex permittivity and dielectric loss of materials. It is found that FeNi/C nanofibers with highly carbonized degree display better microwave absorbing properties. The reflection loss (RL) values less than −10 dB can be observed in 12.8–17.2 GHz (a broad bandwidth of 4.4 GHz) with an absorber thickness of only 1.8 mm. The absorber with a thickness of 2.7 mm has the minimum RL value of −24.8 dB at 9.4 GHz. In this regard, these nanofibers are very likely to be used as EM-wave absorbers in practical application. Furthermore, this work provides a useful strategy to optimize electromagnetic parameters and absorption abilities of metal/carbon absorbers. It may promote the development of 1D metal/carbon composites in microwave absorption field.