Synthesis of the morphology-controlled porous Fe₃O₄ nanorods with enhanced microwave absorption performance

The porous Fe₃O₄ nanorods have been successfully fabricated via a facile and energy-efficient hydrothermal method based on SiO₂-coated β-FeOOH nanorods as a precursor. The effect of SiO₂ coating on the phase structure and morphology of as-prepared samples have been systematically characterized by X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscope (TEM). SEM and TEM results reveal that the Fe₃O₄ nanorods possess one-dimension configuration and the porous structure. The complex permittivity and permeability of the sample are studied in the frequency range of 2.0–18.0 GHz with 55 wt% of porous Fe₃O₄ nanorods in paraffin. For the Fe₃O₄ nanorods, the maximum reflection loss (RL) is − 41.5 dB at 10.24 GHz and the effective absorption bandwidth below − 10 dB can achieve 5.2 GHz (9.28–14.48 GHz) with a matching thickness of 2.4 mm. The enhanced microwave absorption performance is mainly originated from multi-reflection between nanorods and interface polarization, which is related to special rod configuration and the porous structure of the porous Fe₃O₄ nanorods. This work proposes a promising method to tune the microwave absorption performance via morphology control.