Synthesis of ZnS quantum dots and CoFe₂O₄ nanoparticles co-loaded with graphene nanosheets as an efficient broad band EM wave absorber

In order to obtain the high-performance electromagnetic (EM) wave absorber, nanocomposites have been applied to absorbing field. In our research, hybrid reduced graphene oxide (RGO)/CoFe₂O₄/ZnS nanocomposites were successfully synthesized via a facile hydrothermal process in combination with the co-precipitation route. The crystal structure, chemical composition and morphology of the as-prepared nanocomposites have been detailedly investigated. The ZnS quantum dots and CoFe₂O₄ nanoparticles with an average diameter of 3–8 nm and 10–20 nm, respectively, were homogeneously anchored on graphene sheets. Moreover, the EM parameters of both RGO/CoFe₂O₄ and RGO/CoFe₂O₄/ZnS nanocomposites were measured using a vector network analyzer. The EM wave absorption properties of RGO/CoFe₂O₄/ZnS nanocomposites are significantly improved compared with RGO/CoFe₂O₄ nanocomposites, with the maximum reflection loss as high as −43.2 dB at only 1.8 mm and the maximum absorption bandwidth (<−10 dB) of 5.5 GHz (from 10.2 to 15.7 GHz) at 2.0 mm. And the absorption bandwidth (<−20 dB) is up to 6.3 GHz with a thickness in the range of 1.5–2.5 mm. Moreover, the absorption bandwidth (<−10 dB) almost covers the whole frequency range (from 3.6 to 18.0 GHz) with the thickness range of 1.5–5.0 mm. Consequently, it is believed that the as-prepared nanocomposites could be used as promising materials for stealth camouflage techniques.