Facile synthesis of core-shell FeSe2/MoSe2 composites with tunable microwave absorption at low filler mass loading

Transition metal dichalcogenides (TMDs) are typical dielectric materials with a large specific surface area and unique electronic properties, offering potential microwave absorption capabilities. In this study, a series of FeSe₂/MoSe₂ core-shell composites were successfully constructed via a simple one-step hydrothermal reaction. By incorporating FeSe₂ into MoSe₂ nanosheets, interface/dipole polarization and conductive loss are precisely tuned. The gradual increase in FeSe₂ content within the MoSe₂ nanosheets effectively optimizes their impedance matching characteristics and enhances their microwave attenuation capability. The synthesized FeSe₂/MoSe₂ composites demonstrate outstanding microwave absorption performance. Notably, the well-designed FeSe₂/MoSe₂ composite achieves a minimum reflection loss (RL_min) of -58.57 dB at 12.48 GHz with a relatively low filler mass loading (25 wt.%), and an effective absorption bandwidth (EAB, RL<-10.0 dB) of 4.80 GHz (10.56-15.36 GHz) at the thickness of 2.10 mm. When the matching thickness is reduced to 1.82 mm, RL_min reaches -52.62 dB at 14.72 GHz, with a corresponding EAB as high as 5.44 GHz (12.56-18.00 GHz), nearly covering the entire Ku-band. Various microwave attenuation mechanisms, including multiple scattering, interfacial polarization loss, dipole polarization loss, and conductive loss, contribute to the enhanced microwave absorption performance. This work provides a feasible approach for designing tunable microwave absorbers in the field of electromagnetic protection.