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

Abstract

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.