In situ synthesis of novel urchin-like ZnS/Ni3S2@Ni composite with a core-shell structure for efficient electromagnetic absorption

A novel urchin-like ZnS/Ni3S2@Ni composite with a core-shell structure was successfully synthesized by a facile two-stage method. The structure and morphology were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive spectrometry. The influence of reaction temperature on the structure and morphology of the ZnS/Ni3S2@Ni products was investigated by the aid of XRD and SEM techniques. A plausible formation mechanism for the core-shell urchin-like architectures was proposed based on temperature dependent experiments. Electromagnetic absorption measurements show that the urchin-like ZnS/Ni3S2@Ni composite possesses outstanding electromagnetic absorption properties compared with other ZnS/Ni3S2@Ni composites. The optimal reflection loss of -27.6 dB can be observed at 5.2 GHz and the effective absorption (below -10 dB, 90% electromagnetic absorption) bandwidth is 2.5 GHz (12.2-14.7 GHz) with a thickness of only 1.0 mm. The location of the minimum reflection loss can be tuned between 4.6 GHz and 18.0 GHz for the absorber by tuning the thickness between 0.8-2.5 mm. The enhanced electromagnetic absorption properties were attributed to a synergistic effect between dielectric loss and magnetic loss, multiple interfacial polarization resulting from the heterogeneous structure of the core-shell ternary ZnS/Ni3S2@Ni composite, good impedance matching and a unique urchin-like structure.