Interface compatibility engineering of Multi-shell Fe@C@TiO2@MoS2 heterojunction expanded microwave absorption bandwidth

Abstract Due to the unique interfacial polarization and the synergy magnetic-dielectric loss, multi-component core-shell microspheres have been attracting extensive attention as microwave absorption (MA) materials. However, the combination of different dielectric shells to regulate the wider microwave frequency response range still remains a huge challenge, which limits the final practical application. Herein, a hierarchical multi-shell Fe@C@TiO2@MoS2 (FCTM) microsphere is fabricated via an in-situ reduction process. By tuning the types and numbers of dielectric shell surrounding on the magnetic Fe core, the complex permittivity of obtained core-shell MA microspheres could be optimized to extend the absorption bandwidth. In our FCTM microspheres, the hierarchical interfacial polarization can be significantly promoted by forming compatible interfaces involving Fe-C, C-TiO2 and TiO2-MoS2. Dielectric dissipation was much promoted via the designed intermitted carbon layer which contributes remarkable conduction loss, while the magnetic loss capability was boosted by the coupling effects among adjacent microspheres. Consequently, the multi-shell Fe@C@TiO2@MoS2 composites exhibit an excellent MA performance with the minimum reflection loss (RLmin) of -54.2 dB at 2.5 mm. Importantly, the efficient absorption bandwidth (RL