Defect and interface engineering are efficient approaches to adjust the physical and chemical properties of nanomaterials. In order to effectively utilize these strategies for the improvement of microwave absorption properties (MAPs), in this study, we reported the synthesis of hollow carbon shells and hollow carbon@MoS₂ nanocomposites by the template-etching and template-etching-hydrothermal methods, respectively. The obtained results indicated that the degree of defect for hollow carbon shells and hollow carbon@MoS₂ could be modulated by the thickness of hollow carbon shell, which effectively fulfilled the optimization of electromagnetic parameters and improvement of MAPs. Furthermore, the microstructure investigations revealed that the precursor of hollow carbon shells was encapsulated by the sheet-like MoS₂ in high efficiency. And the introduction of MoS₂ nanosheets acting as the shell effectively improved the interfacial effects and boosted the polarization loss capabilities, which resulted in the improvement of comprehensive MAPs. The elaborately designed hollow carbon@MoS₂ samples displayed very outstanding MAPs including strong absorption capabilities, broad absorption bandwidth, and thin matching thicknesses. Therefore, this work provided a viable strategy to improve the MAPs of microwave absorbers by taking full advantage of their defect and interface engineering.

In order to effectively utilize the magnetic-dielectric synergy and interfacial engineering, in this paper, yolk–shell structured magnetic multicomponent nanocomposites (MCNCs) including CoNi@void@C and CoNi@void@C@MoS₂ were produced in large scale by in-situ pyrolysis of cubic CoNi Prussian blue analogs (PBAs) followed by the hydrothermal process, respectively. Because of their unique structures, excellent synergistic effect between dielectric and magnetic loss, the as-prepared CoNi@void@C and CoNi@void@C@MoS₂ MCNCs displayed very outstanding electromagnetic wave absorption performances (EMWAPs) including strong absorption capabilities, broad absorption bandwidth and thin matching thicknesses. Furthermore, the as-prepared CoNi@void@C and CoNi@void@C@MoS₂ MCNCs well maintained the cubic configuration of CoNi PBAs even after the thermal treatment and hydrothermal processes. The unique structure and formed carbon layers effectively prevented the corrosion of internal CoNi alloy during the formation of MoS₂, and CoNi@void@C@MoS₂ MCNCs with different MoS₂ contents could be synthesized by controlling the hydrothermal temperature. The obtained results revealed that the EM parameters, dielectric and magnetic loss capabilities of CoNi@void@C@MoS₂ MCNCs could be tuned by controlling hydrothermal temperature and filler loading, which made their outstanding EMWAPs could be achieved in different frequency regions. Taking account of simple process, low density and high chemical stability, our findings provided a new and effective pathway to develop the strong wideband microwave absorbers.