Optimizing the microwave absorption properties of core–shell NiO@FeNiMo nanocomposites by regulating the oxide shell thickness

•The thickness of the NiO shell of NiO@FeNiMo nanocomposites could be regulated.•This oxide coated core-shell NiO@FeNiMo nanocomposite is a promising absorber.•The oxidation synthetic process is easy to implement, the industrial production could be expected. Oxide coated nanocomposite NiO@FeNiMo with core–shell structure were fabricated by plasma arc-discharging and oxidative heat treatment method. By optimizing the impedance matching, the absorbing properties of the oxide coated core–shell NiO@FeNiMo were improved significantly. By varying the coating thickness from 1.0 ∼ 5.0 mm, the reflectivity of less than −10 dB, in the frequency range of 4–17 GHz, was obtained in NiO@FeNiMo nanocomposites oxidized at 473 and 498 K. The minimum reflectivity of −54.0 dB at 12.8 GHz (d = 1.47 mm) was achieved by oxidizing the sample at 473 K. The oxide coated core–shell NiO@FeNiMo absorber reported in this paper have the potential be a powerful candidate for microwave absorbing materials for its excellent absorption, simple preparation process, and high stability in complex environments.