Design of conical hollow ZnS arrays vertically grown on carbon fibers for lightweight and broadband flexible absorbers.

High-performance electromagnetic (EM) absorbers are necessary for military and industry application in view of the extensive utilization of EM devices. Carbon fibers (CFs) have been considered as promising candidates in electromagnetic wave (EMW) absorption materials, while the single carbon fiber material cannot achieve satisfactory EMW absorption performance because of its limited impedance matching. Herein, electrodeposition and hydrothermal methods were used to fabricate vertical hollow ZnS nanoarrays on carbon cloth (CC) substrate, and then one kind of novel flexible EM composite absorbers with excellent performance was obtained through adjusting morphology of hollow ZnS nanoarrays by easily changing the synthesis parameters of the precursor. Noteworthy, the miniaturized cone-shaped hollow ZnS nanoarray composite absorber shows excellent EMW absorption performance of strong absorption and wide absorption band. The maximum reflection loss value is -52.5 dB and the effective absorption bandwidth reaches 5.1 GHz when the thickness is only 1.9 mm. At the same time, the composite possesses the characteristics of light weight and thin thickness. The excellent properties of the composite absorbers are mainly attributed to their morphological structure. The unique hollow ZnS nanoarray structure enhances the interface polarization and multiple reflections, meanwhile also giving it the properties of metamaterials with resonant absorption. Furthermore, the adjustment of the ZnS nanoarray morphology can not only change the transmission behavior of EMW but also affect the resonance frequency and intensity of the ZnS nanoarray unit. This study obtains high-performance absorbing materials with flexible characteristics as well as highlights the importance of the adjustment of the morphological structure to improve the EMW absorption performance.