Preparation And Performance Study Of Core-shell Structure Co_xFe_3-xO₄@MoS₂ Composite

The so-called absorbing material refers to a kind of material which can absorb or greatly weaken the electromagnetic wave energy and thus reduce the electromagnetic interference.In practical application,the excellent absorbing materials not only require high absorptivity to electromagnetic waves in a wide frequency band,but also require its light weight,temperature resistance,moisture resistance,corrosion resistance and so on.In order to obtain the excellent comprehensive properties of microwave absorbers,core@shell structured Co_0.6Fe_2.4O₄@MoS₂ nanocomposites were elaborately constructed and synthesized by a facile two-step hydrothermal method.Due to the independence of the two-step processes,the method could be applied to produce different categories of Mo S₂ based nanocomposites.The obtained results demonstrated that the as-prepared Co_0.6Fe_2.4O₄@MoS₂ nanocomposites exhibited superior electromagnetic wave absorption performances with very low minimum reflection loss(RL_min)value and broad absorption bandwidth at thin matching thicknesses.Impressively:（1）The optimal RL_min value reached-79.9 d B at 11.2 GHz with a thickness of2.73 mm.In addition,the effective bandwidth of 5.96 GHz was observed with thicknesses of 2.34 mm and 2.98 mm.（2）Taking into account their the low cost of production,high stability and controllability,the obtained results demonstrated that the Co_0.6Fe_2.4O₄@MoS₂ nanocomposites achieved in this study are very attractive candidates for new types of high performance microwave absorbers.Moreover,we believe that constructing core@shell structured Mo S₂-based nanocomposites is a reliable strategy to accelerate advancements of microwave absorbers.Herein,positive and reverse core@shell structure Co_xFe_3-xO₄@Mo S₂（x=1.5,0.75 and 0.5）and Mo S₂@Co_xFe_3-xO₄（x=0.5）nanocomposites were elaborately produced through an inexpensive two-step hydrothermal process.（1）It was found that the Co_xFe_3-xO₄@Mo S₂ samples exhibited a much smaller optimal RL_min value and a broader frequency bandwidth（f_b）with the lower value of matching thickness（d_m）when the Co_xFe_3-xO₄@Mo S₂ loadings were raised to 60 from30 wt%.With the x value decreasing from 1.5 to 0.5,the obtained Co_xFe_3-xO₄@Mo S₂samplesdisplayed a much smaller RL_min value with a thinner d_m and a much larger f_bvalue with the thin d_m（～2 mm）.（2）The sample consisting of 60 wt%Co_xFe_3-xO₄@Mo S₂（x=0.5）exhibited an RL_min value of-66.83 d B with the d_m of merely 1.57 mm,and its corresponding f_bvalue could reach 6.64 GHz with the d_m of 2.02 mm.Moreover,compared with the Mo S₂@Co_xFe_3-xO₄（x=0.5）sample,the Co_xFe_3-xO₄@Mo S₂（x=0.5）sample displayed evidently better microwave absorbing comprehensive performances in terms of low RL_min value,large f_b value,and high chemical stability.Generally,the obtained results demonstrated that the designed Co_xFe_3-xO₄@Mo S₂ nanocomposites could act as microwave absorbers with outstanding comprehensive properties.