Core-shell structured Fe/Fe₃O₄@TCNFs@TiO₂ magnetic hybrid nanofibers: Preparation and electromagnetic parameters regulation for enhanced microwave absorption

In this paper, a three-step method has been applied for preparation of Fe/Fe₃O₄@TCNFs@TiO₂ magnetic hybrid nanofibers (MHNFs) with three-layer core-shell structure. Firstly, tubular polymer nanofiber precursors with FeCl₃ embedded in axis (TPNFPs) are synthesized by a confined self-condensation system developed earlier. After high-temperature conversion, tubular magnetic carbon nanofibers loaded with Fe nanoparticles inside (Fe@TCNFs) are obtained. Finally, TiO₂ shell formation procedure is carried out by the hydrolysis of tetrabutyl titanate, and MHNFs with different TiO₂ loadings are successfully fabricated. This material possesses both magnetic and dielectric loss abilities that shows excellent microwave absorbing performance. Under filler content of 15 wt%, the minimum reflection loss reaches −44.8 dB@13.9 GHz, and the absorbing layer thickness is only 1.6 mm. In addition, the electromagnetic parameters of MHNFs can be regulated and optimized by adjusting TiO₂ loading. It brings better impedance matching property and improves microwave absorbing performance. Meanwhile, the composition, structure and electromagnetic parameters of MHNFs are systematically analyzed. The microwave attenuation mechanism is revealed. This study has guiding significance for the performance optimization of existing microwave absorbers.