Chain-like Fe3O4@void@mSiO2@MnO2 composites with multiple porous shells toward highly effective microwave absorption application

Abstract High-efficiency microwave absorbers have become in heavy demand together with the development of 5G information technology, for they can defend against serious electromagnetic interference and radiation. Here, chain-like Fe3O4@void@mSiO2@MnO2 composites with multiple porous shells have been successfully prepared and applied in the field of microwave absorption. Due to the special microstructure and components, these composites are endowed with a high specific surface area of 201.50 m2/g and saturation magnetization of 28.6 emu/g. With loading 40 wt % absorbers in the paraffin, Fe3O4@void@mSiO2 composites can possess broader absorbing bandwidth of 6.80 GHz while Fe3O4@void@mSiO2@MnO2 composites exhibit effective absorption in the range of 10.49–15.62 GHz (5.13 GHz) at the thinner layer thickness, moreover, the latter ones can acquire the minimum reflection loss value of −45.76 dB. The results demonstrate that the introduction of hierarchical MnO2 shells contributes to improving the microwave absorption properties, meanwhile, it is implied that construction of multiple porous shells benefits broadband microwave absorption. Analyses of electromagnetic parameters reveal that microwave absorption mechanisms mainly involve impedance matching, abundant interfacial polarization, multiple scattering and reflections, natural resonance, and exchange resonance. This work provides a new strategy to achieve broadband microwave absorbers.