Ferromagnetic hierarchical carbon nanofiber bundles derived from natural collagen fibers: truly lightweight and high-performance microwave absorption materials

Abstract

High-performance microwave absorption materials with a broad bandwidth and strong intensity have significant applications in both civil and military areas. To obtain the desired materials, the current strategy mainly relies on increasing the thickness of the materials to prolong the transmission routes of microwaves so as to tune the frequency and intensity of absorbed microwave. Unfortunately, these approaches inevitably lead to the increase of mass weight of microwave absorption materials, and the microwave absorbing band may go beyond the targeted bandwidth due to the wave shift caused by the change of the absorber thickness. Herein, a biotemplated synthesis method is developed to fabricate 3D ferromagnetic hierarchical carbon nanofiber bundles (FHCNBs) using natural collagen fibers as the biotemplate, in which ferromagnetic nanoaprticles (NPs) are embedded on the HCNBs with high dispersity. For the as-prepared FHCNBs, the hierarchically nanofibrous structure induced-multiple reflection and scattering are able to enlarge the transmission routes of microwaves, which dramatically improves the microwave attenuation capacity of the ferromagnetic NPs exposed on the FHCNB surface. In this way, a low loading amount of active components (as low as 38.1%) is required for achieving excellent microwave absorption performances (e.g. −36 to −57 dB of reflection loss, 8.6–14 GHz with reflection loss exceeding −10 dB). Importantly, the bandwidth and absorption intensity of microwaves can be effectively tuned by changing the ferromagnetic species (Fe₃O₄, Fe₃N, α-Fe, FeTiO₃/Fe₃O₄ and ZrO₂/Fe₃O₄) embedded on FHCNBs, which therefore provides a new pathway for the rational realization of truly lightweight and high-performance microwave absorption materials.