Construction of core-shell ZnO@ZnO/FeNi microrods with improved impedance matching and electromagnetic wave absorption performance

Functional core-shell heterostructure, which can integrate the characteristics of multiple components to achieve synergistic effects, have been widely explored in electromagnetic wave (EMW) absorption materials. In this work, core-shell ZnO@ZnO/FeNi microrods (MRs) derived from ZnO@ZnFeNi hydroxide (ZnFeNi OH) are prepared by a simple hydrothermal reaction and subsequent pyrolysis process. The introduction of FeNi alloy helps to optimize the impedance matching of ZnO, thus improving the EMW absorption performance. The different impedance matching properties of core-shell ZnO@ZnO/FeNi MRs are realized by adjusting the ZnO/ FeNi shell thickness by changing the hydrothermal reaction time. When the hydrothermal time is 10 h, the core-shell ZnO@ZnO/FeNi MRs supplies the optimal EMW absorption performance with the minimum reflection loss of-53.7 dB and the widest absorption bandwidth of 5.3 GHz at a filler content of 33%. The synergistic effect of ZnO-FeNi interfacial polarization and the strong dielectric-magnetic loss are responsible for its superior EMW absorption performance. This work provides a valuable strategy for constructing core-shell dielectric@ magnetic composites to obtained high efficiency absorber.