Hydrothermal Synthesis and Microwave Absorption Properties of Nickel Ferrite/Multiwalled Carbon Nanotubes Composites

It is well accepted that the microwave absorption performance of ferrite can be enhanced via the hybridization. However, it is still very challenging to design the hierarchical nanostructure of ferrite hybrids to fabricate wave absorbing composites with both the high efficiency and lightweight. Herein, we successfully realize the in-situ synthesis of nickel ferrite/multiwalled carbon nanotubes (NiFe2O4/MWCNTs) hybrids with a large-scale production by the hydrothermal method. The structural characteristics, morphology, electromagnetic and microwave absorption properties were analyzed by X-ray diffraction, scanning electron microscope and vector network analyzer. The morphological study shows that NiFe2O4 nanoparticles with a small size (tens of nanometers) are coated on the MWCNTs, leading to a three-dimensional hierarchical nanostructure. The NiFe2O4/MWCNTs hybrids show satisfied microwave absorption properties. Typically, the optimized sample shows the minimum reflection loss of −19 dB at 11.3 GHz, and the bandwidth of the reflectivity below −10 dB is 2.5 GHz with a thin thickness of 1.5 mm. This result shall be due to the improved dielectric losses or interface polarization etc. Our results demonstrate a facile approach for the design of ferrite-based microwave absorber to meet the requirements of lightweight, thin-thickness and high efficiency.