Abstract
The NiO/NiCo2O4 mixtures with unique yolk-shell structure were synthesized by a simple hydrothermal route and subsequent thermal treatment. The elemental distribution, composition, and microstructure of the samples were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and scanning electron microscope (SEM), respectively. The microwave absorption property was investigated by using vector network analysis (VNA). The results indicated that the excellent electromagnetic wave absorption property of the NiO/NiCo2O4 mixtures was achieved due to the unique yolk-shell structure. In detail, the maximum reflection loss (RL) value of the sample reached up to − 37.0 dB at 12.2 GHz and the absorption bandwidth with RL below − 10 dB was 4.0 GHz with a 2.0-mm-thick absorber. In addition, the NiO/NiCo2O4 mixtures prepared at high temperature, exhibited excellent thermal stability. Possible mechanisms were investigated for improving the microwave absorption properties of the samples.
Highlights
With arising and development of wireless communication and the wide application of electronic devices, electromagnetic contamination has become serious problems to the electronic equipment [1]
The X-ray diffraction (XRD) patterns show that the NiO/NiCo2O4 mixtures are successfully synthesized by using the raw materials mentioned in the experiment
In the hydrothermal reaction stage, due to the participation of urea, we obtain a small amount of NiCO3, which can be decomposed to NiO and CO2 at high temperature
Summary
With arising and development of wireless communication and the wide application of electronic devices, electromagnetic contamination has become serious problems to the electronic equipment [1]. High-power electromagnetic wave in regional environment can interfere with each other, which can result in the damage of communication system or even cause serious accidents, such as missile error, aircraft crash, and other disastrous consequences. To develop a high-efficiency electromagnetic wave absorption (EMW) absorber with strong absorption, wide bandwidth, small thickness, and lightweight is highly desirable. 13.4 GHz. the method used in the preparation of the NiO/NiCo2O4 hybrid process is too complicated to be suitable for mass production. The development of a facile method for the preparation yolk-shell NiO/NiCO2O4 mixtures with excellent EMW performance is still an intriguing topic
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