3D Nest-Like Architecture of Core-Shell CoFe₂O₄@1T/2H-MoS₂ Composites with Tunable Microwave Absorption Performance

As a promising microwave absorber filler, molybdenum disulfide (MoS₂), because of the unique structure, high electrical conductivity, and polarization effect, is receiving more and more interest. Developing MoS₂-based composites with specific structure and morphology is a hot top in the field of microwave absorbers, because of its strong multiple scattering and reflecting for microwaves as well as its unique interfacial characteristics. Now, with a facile solvothermal method, a novel core-shell CoFe₂O₄@1T/2H-MoS₂ composite is synthesized, where the CoFe₂O₄ nanospheres are entirely embedded in a special three-dimensional (3D) nest-like 1T/2H phase MoS₂. Notably, in comparison with superparamagnetic CoFe₂O₄ nanospheres, the coercivities of as-synthesized CoFe₂O₄@1T/2H-MoS₂ composites greatly increase. Here, 1T/2H-MoS₂ exhibits ferromagnetism superimposed onto large diamagnetism. It is noted that, by adjusting the content of 1T/2H-phase MoS₂, the microwave absorption performance of as-synthesized composites can be effectively tuned. The combination of 1T/2H-MoS₂ with CoFe₂O₄ helps to adjust the permittivity and optimize the impedance matching of the composites. Impressively, a minimum reflection loss (RL_min) of -68.5 dB for the as-synthesized composites with a thickness of 1.81 mm is gained at 13.2 GHz; meanwhile, a broad effective bandwidth of 4.56 GHz ranged from 13.2 to 17.76 GHz is achieved at 1.6 mm. Further, the overall effective bandwidth (RL < -10 dB) is obtained up to 14.5 GHz from 3.5 to 18.0 GHz, covering more than 90% of the measured frequency range. The high microwave absorption performance is ascribed to the special structure design with the core of magnetic CoFe₂O₄ nanospheres and the shell of dielectric nest-like 1T/2H-MoS₂ as well as their appropriate impedance matching. From the perspective of basic research and practical microwave application, this study provides another feasible and effective pathway to design novel MoS₂-based magnetic/dielectric microwave absorbers.