A multi-layer core-shell structure CoFe₂O₄@Fe₃C@NiO composite with high broadband electromagnetic wave-absorption...

Enhancing the absorption strength of electromagnetic waves and broadening the absorption band are constant goals in designing and preparing absorbing materials. The use of composites has shown to be a very efficient method for acquiring broadband-absorbing materials, while the construction of a core-shell structure has demonstrated a significant enhancement in absorption capability. In this paper, the nanocomposite metal-organic framework (MOF) derivative CoFe₂O₃@C with a double core-shell structure and the nanocomposite MOF derivative CoFe₂O₄@Fe₃C@NiO with a three-layered core-shell structure have been prepared using a chemical compound. The multi-layer structure provides more active sites for the multiple reflection and scattering of electromagnetic waves, effectively improving the attenuation capability. The effective absorption band (EAB) (reflection loss (RL) ≤ -5 dB) of both CoFe₂O₃@C and CoFe₂O₄@Fe₃C@NiO are broadened compared to that of the ZIF-67 derivative. In particular, the minimum reflection loss (RL_min) of CoFe₂O₃@C was -52.7 dB at 13.3 GHz and 2.04 mm, and the EAB (RL ≤ -5 dB) is as wide as 9.35 GHz. Compared with the ZIF-67 derivative, the EAB exhibits a twofold rise, accompanied by a corresponding thickness increase of just 0.24 mm. At a matched thickness of 2.2 mm, the EAB of CoFe₂O₄@Fe₃C@NiO can even reach 11.9 GHz.