Structure and performance of Ni@Ni₃S₂ foam for microwave absorption

To achieve impedance matching for microwave absorption, multi-component powder absorbers have attractive aspects. However, conventional designs require mixing the absorber with an adhesive to coat the protected device, resulting in the risk of the coating peeling, and limiting the potential applications of the absorber and expansion of the production scale. Hence, developing a high-performance absorber with an easy fabrication method and low cost is a significant goal. In this paper, a series of Ni@Ni₂S₃ foams of varied Ni/S ratios were synthesized by a one-step in situ hydrothermal reaction. The foams of different composition had different morphologies that were investigated by x-ray diffraction, x-ray photoelectron spectroscopy, and scanning electron microscopy. The results reveal that Ni@Ni₂S₃ foam possesses a wide, effective attenuation bandwidth (<  −10 dB reflection loss (RL) from 12.75 to 18.0 GHz)) and an intense RL (−50.7 dB) as an electromagnetic (EM) wave absorber for a thickness of 3.6 mm. In addition, compared to powder absorbers, Ni@Ni₂S₃ foam possesses unique advantages. With a simplified formation process, it is a promising multifunctional material, which in addition to protecting against EM wave pollution, can improve mechanical properties as a result of the metal skeleton it provides. (paper)