Preparation And Properties Of CoNi-based MoS₂ Composites With Core-shell Structur

With the booming of nanotechnology,microwave absorbing materials have demonstrated many advanced electromagnetic functions,including radiation protection and anti-radar stealth.Tremendous efforts have been devoted to regulating microstructure because of the advantages of interface polarization and magnetic dielectric synergy for the improvement of electromagnetic wave attenuation capability.Considering the coexistence of multiple loss mechanisms and synergistic effects brought by the compounding of magnetic and dielectric materials,we have chosen the magnetic metal alloy CoNi as the substrate and compounded it with the two-dimensional dielectric material MoS₂,which has a unique energy band structure and good semiconductor properties.And the core-shell structure can both modulate the microstructure and utilize the interfacial effect between the core and the shell to enhance the properties of the materials.Herein,the core-shell structure CoNi-based MoS₂ complexes were designed to achieve multiple loss mechanisms through multi-material composite and morphology optimization.A large amount of literature has been researched and the mechanisms involved have been carefully analyzed.（1）Firstly,the flower-like core@shell structured CoNi₂S₄/Co₉S₈@MoS₂nanocomposites were synthesized through an in-situ hydrothermal reaction between the Moand S sources on the surface of CoNi nanoparticles.By changing the hydrothermal temperature,the flower-like geometrical morphology of samples could be effectively optimized.Although the excellent microwave absorption performance of the sample was achieved due to the excellent interface effect,the introduction of MoS₂led to the sulfuration of CoNi during the preparation process.（2）Therefore,in order to effectively utilize the magnetic-dielectric synergy and interface engineering,CoNi@void@C and CoNi@void@C@MoS₂ magnetic multicomponent nanocomposites with yolk-shell structure were prepared by an in-situ pyrolysis of cubic CoNi Prussian blue analogs（PBAs）followed by hydrothermal process on a large scale,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 displayed very outstanding electromagnetic wave absorption performances including strong absorption capabilities,broad absorption bandwidth and thin matching thicknesses.Furthermore,the as-prepared CoNi@void@C and CoNi@void@C@MoS₂ well maintained the cubic configuration of CoNi PBAs even after the pyrolysis and hydrothermal processes.The formed carbon layers effectively prevent the corrosion of internal CoNi alloys during the formation of MoS₂,and CoNi@void@C@MoS₂ with different MoS₂ contents could be synthesized by controlling the hydrothermal temperature.The obtained results revealed that the electromagnetic parameters,dielectric and magnetic loss capabilities of CoNi@void@C@MoS₂ could be tuned by controlling hydrothermal temperature and filler loading,which made their outstanding electromagnetic wave absorption performances achievable in different frequency regions.