Preparation Of Heterostructured CNTs-based Composites And Their Absorbing Properties

In recent years,intense efforts have being devoted to the development of nanomaterials with low reflection loss(RL),thin matching thickness(d_m),wide bandwidth(f_b)and low density aimed at improving their microwave absorption efficiency and simultaneously employing simple preparation process.In this paper,we synthesized a new class of microwave absorbing materials by constructing van der Waals heterostructures and combining various components with different properties.Below are the specifics of this research:(1)In order to improve the microwave absorption performance of the material,we reported a simple hydrothermal route to synthesize heterostructure CNTs@Mo S₂nanocomposites.By controlling the amounts of initial Mo and S sources,different Mo S₂ contents of CNTs@Mo S₂nanocomposites were selectively produced.The results showed that the CNTs@Mo S₂nanocompo sites displayed excellent microwave absorption properties owing to synergistic effects of heterostructures and unique nanoflower morphology of Mo S₂.The microwave absorption properties could be improved significantly by optimizing the Mo S₂ contents and the filler loadings.Impressively,when the filler loading is 40 wt%,the CNTs@Mo S₂ sample could simultaneously displayed the minimal reflection loss(RL_min)value of-54.75 d B with the very thin d_m of 1.49 mm,and f_b value of 4.0 GHz at the low thicknesses of 1.26 mm.The investigations revealed that the designed CNTs@Mo S₂ displayed extraordinary comprehensive microwave absorption properties,which could provide a reliable strategy to design high-performance microwave absorbers considering the low cost and high stability.(2)In order to exploit the advantage of the double loss mechanism,multiple interface structures and fascinating properties of carbon materials,we propose a simple strategy to elaborately design and produce the heterostructure Fe@Fe₃C@CNTs/reduced graphene oxide(RGO)nanocomposites by a combined method of hydrothermal reaction and chemical vapor deposition.The regulation of CNTs'content indicated that the electromagnetic and microwave absorption properties of the nanocomposites could be designed by controlling the decomposition temperature.The Fe@Fe₃C@CNTs/RGO nanocomposites simultaneously presented extremely strong microwave absorption capabilities and large absorption bandwidth with very thin d_m.In particular,the samples obtained at 500 and 550?simultaneously displayed very low RL_min values of-62.29 d B at 15.16 GHz with the d_m value of 1.79mm and-74.31 d B at 11.56 GHz with the d_m value of 2.14 mm,respectively.Their f_bvalues were 6.00 GHz with the d_m value of 1.87 mm and 6.00 GHz with the d_m value of1.85 mm.Compared to the previously reported related microwave absorbers,the designed heterostructure Fe@Fe₃C@CNTs/RGO nanocomposites could be utilized as good lightweight and high efficiency microwave absorbers as it displays superior comprehensive electromagnetic wave absorption properties.