Preparation Of Group VB Transition Metal Dichalcogenides And Research On Their Electromagnetic Wave Absorption Properties

In recent years,the increasing varieties and numbers of electronic products and communication devices has exacerbated the phenomenon of hidden harmful electromagnetic radiation pollution.The development and application of wave absorbing materials is a highly visible and active research topic in materials science.In the civilian field,electromagnetic protection can reduce the impact of electromagnetic radiation on the body and life,and improve public health indicators.In the military field,electromagnetic protection allows military units and weapons to evade radar detection,enhancing combat effectiveness and longevity.Transition metal disulfides(TMDs),the star material in two-dimensional(2D)dielectric materials,are a fundamental building block in the design of wave absorbing materials.Currently,the most common materials used for wave absorbing material construction are Group VIB TMDs represented by molybdenum disulphide(MoS₂)and tungsten disulphide(WS₂).However,the few active sites of these materials are located only at the edges of the nanosheets and the poor electrical conductivity of the Group VIB TMDs cannot achieve a high impedance match,which seriously hinders development in the field of electromagnetic wave absorption.Recent studies have found that VB group TMDs with more electrochemically active sites at the edges and inside of the nanosheets have more unique advantages,and we believe that VB group TMDs have better prospects for applications in the field of electromagnetic wave absorption.In addition,different materials respond differently to electromagnetic waves.The study of VB group TMDs provides a richer base material for the design of wave absorbing materials and provides a good basis for subsequent in-depth studies of wave absorbing properties.This work presents a detailed analysis of the preparation process,wave absorption properties and absorption mechanisms of two typical VB group TMDs,vanadium disulfide(VS₂)and niobium disulfide(NbS₂),with different morphologies of respectively.(1)Explore the optimal preparation process for VS₂ nanomaterials with excellent wave absorption properties.VS₂ nanosheets with certain wave absorption properties were prepared by the simple one-step hydrothermal method using ammonium metavanadate as the vanadium source,thiourea and thioacetamide as the main sulphur sources,polyvinylpyrrolidone as the surfactant to modulate the morphology.After hydrothermal reaction at 210 ? for 24 h,the coaxial stacked VS₂ nanosheets were obtained,and the electromagnetic parameters and properties of the nanosheets were analysed.The results show that VS₂ has excellent wave absorption properties and achieves dual frequency microwave absorption in the C and Ku bands,which can be further applied to develop a good filter and open up new avenues for the development of materials with excellent wave absorption properties.(2)Explore the process of preparing NbS₂ nanomaterials using solvent heat and investigate the potential wave absorption mechanism.This work pioneered the synthesis of NbS₂ using the facile solvent heat.Organic solvents such as trichloromethane were used as the reaction system,niobium pentachloride and various sulphur sources were employed as reaction precursors to explore the synthesis pathway of NbS₂.The reaction temperature,reaction time and other process parameters of the solvent heat were optimized to explore and prepare NbS₂ nano-absorbing materials with excellent wave absorption performance.The results show that the obtained hollow spheres resembling ideal black bodies,and NbS₂ hollow open-hole nanomicrospheres with large specific surface area and small aperture opening structure have excellent wave absorption performance,achieving effective absorption performance covering the entire 12-18 GHz broadband at a thickness of 2.0 mm.