Preparation Of CoS₂ With Different Morphologies And Research On Electromagnetic Wave Absorption Properties Of Their Composite Material

Human beings are developing and society is progressing.Electronic products bring convenience and harm at the same time.The consequent electromagnetic wave pollution and electromagnetic wave radiation have become urgent problems to be solved.When people are exposed to electromagnetic wave pollution for a long time,studies have shown that electromagnetic wave energy will cause direct damage to the central nervous system,immune deficiency system and cardiovascular system of the human body.And because parasitic radiation can create obstacles to electronic systems,other electronic devices may not work properly.In addition,electromagnetic wave pollution and leakage will also cause fatal damage to national security.In order to cope with this situation,the research of electromagnetic wave absorbing materials with light weight,wide bandwidth and strong attenuation ability has become the top priority.CoS₂ is a typical transition metal halide（TMDs）with diverse morphologies,excellent conductivity,semi gold properties,inherent chemical and structural stability in acidic and alkaline environments.Using CoS₂ with different morphologies as the base material and compounding with materials such as transition metal sulfides and magnetic particles can fully exploit the loss mechanism of the material,resulting in excellent impedance matching characteristics and attenuation capabilities.In this paper,by selecting CoS₂ and its composites with different morphologies and structures,the effects of different composite mechanisms on the microwave absorbing properties and mechanisms were studied.The main research contents and conclusions are as follows:（1）Preparation of ternary composites by multiple hydrothermal methods and hydrogen reduction.Sheet-like MoS₂ self-assembles on the surface of CoS₂ microspheres,and Fe Ni alloy nanoparticles are freely distributed on the surface of flower-like MoS₂.The crystal structure,defects and microscopic morphology of the material were characterized by XRD,confocal Raman spectrometer and scanning and transmission electron microscope.The synergistic effect of chemical loss（dipole polarization,interface polarization）and magnetic loss（natural resonance and exchange resonance）has excellent electromagnetic wave absorption performance.Specifically,the ternary Fe Ni@MoS₂@CoS₂ composite exhibits remarkable electromagnetic wave absorption performance at 14.32 GHz with a thickness of 2.25 mm,with a RL_min value of-46.8 d B and an EAB of 6.32 GHz.Furthermore,a maximum EAB of 6.96 GHz is achieved at 2.20 mm.（2）M-CoS₂@C（M=Fe,Co,Ni,Cu）composites were prepared by wet impregnation method and high temperature carbon reduction.Firstly,CoS₂ hollow microspheres were prepared by soft template method,and then self-polymerization and high temperature carbonization of dopamine hydrochloride were carried out on CoS₂ microspheres.Finally,M-CoS₂@C（M=Fe,Co,Ni,Cu）composites were obtained by doping and reducing different metals by wet impregnation method.Under the coordination of multiple absorption mechanisms,the ternary composite exhibits remarkable electromagnetic wave absorption performance at a thickness of 2.23 mm at 10.88 GHz,with a RL_min value of-48.90 d B.Furthermore,a maximum EAB of 5.04 GHz is achieved at 1.98 mm.The reason for the excellent electromagnetic wave absorption ability may be the synergistic effect of the material’s conductivity loss and multiple refraction.（3）FeCoS₂@CoS₂ composites were prepared by wet impregnation method and multiple calcinations.Co（CO₃）_0.5（OH）·0.11H₂O hollow sea urchin spheres were first prepared by soft template method,and then calcined twice to obtain CoS₂ with no obvious change in morphology.Then,FeCoS₂@CoS₂ composites were obtained by wet impregnation on CoS₂ hollow sea urchin spheres,sulfided heterobimetallic,and calcined.Under the coordination of multiple absorption mechanisms,the composite exhibits remarkable electromagnetic wave absorption performance at a thickness of 1.97 mm at16.88 GHz with an RL_min value of-75.23 d B.Furthermore,a maximum EAB of 5.76 GHz is achieved at 2.12 mm.The reason for the excellent electromagnetic wave absorption ability may be caused by the synergistic effect of the dielectric loss and magnetic loss of the material,as well as the conductance loss and multiple refraction.