High efficiency fabrication of Co nanosheets deposited by SiO2 layer with controllable permittivity toward superior electromagnetic wave absorption

Abstract

In this study, Co nanosheets covered by SiO2 nanoparticles were synthesized by employing microwave plasma assisted reduction (MPAR) technique, which was high-efficiency and energy-saving. The diagonal dimensions of the prepared nanosheets were in the range of 3–7 µm uniformly on a large scale. It was demonstrated that the flaky morphology with high aspect ratio could inherit well from self-sacrificing precursor, further benefitting for acquiring high complex permeability in the gigahertz frequency region. Meanwhile, the complex permittivity could be effectively engineered by adjusting the deposited amount of SiO2 nanoparticles, which could support sufficient dielectric loss to enhance the attenuation competence and improve the impedance matching. Consequently, the minimum reflection loss could reach up to −53 dB with only 1.5 mm thickness. Furthermore, a wide effective bandwidth from 2.6 to 18 GHz could be achieved by integrating the thickness from 1.0 ∼ 5.0 mm. Such excellent microwave absorption performances supplied the opportunity for applications in the fields of radar stealth and electromagnetic shielding. Besides, it is believed that the developed MPAR method provide new insights for the design and preparation of novel microwave absorption materials with desirable morphologies.