Achieving ultra-broadband electromagnetic absorption of Ag regulated hollow Ag/CuO@CuS through balancing conduction loss and impedance matching

Excellent impedance matching and high conduction loss are important factors for the preparation of high-performance electromagnetic wave (EMW) absorbing materials, but these two properties are often contradictory. In this work, three absorbers with unique hollow structures, H-Ag/CuO@CuS, H-O-Ag/CuO@CuS, and H-P-Ag/CuO@CuS, are designed and synthesized by adopting hollow CuO@CuS with double shell as carrier and silver nitrate as the structural regulator. The more voids coming from hollow structures, window-opened structures, and stacked pores improve the impedance matching of these absorbers, and the introduction of elemental Ag effectively regulates the conduction loss. Therefore, a balance between impedance matching and conduction loss is achieved to improve the reflection loss (RL) value and broadens the absorbing band of the absorbers. In comparison to H-Ag/CuO@CuS and HO-Ag/CuO@CuS (hollow structure with open window) in which elemental Ag is uniformly dispersed in the CuO layer, H-P-Ag/CuO@CuS exhibits more excellent EMW absorption performance due to more voids and an optimized conductive network arising from Ag/CuO pieces distributed between the hollow Ag/CuO@CuS particles and Ag distributed in the CuS layer. When the thickness is 2.3 mm, H-P-Ag/CuO@CuS provides an ultra-wide electromagnetic absorption band of 8.56 GHz (9.44–18 GHz), in which the RL < –10 dB and the minimum reflection loss of –41 dB.