Modification Design Of MoS₂ Based Composite Materials And Research On Their Electromagnetic Wave Absorption Performanc

The rapid advancement of science and technology has brought tremendous convenience to human life and production,but it has also introduced electromagnetic wave pollution as a new source of pollution that is more challenging to mitigate than water,air,and noise pollution.Studies indicate that prolonged exposure to electromagnetic wave pollution can cause direct damage to the immune system and central nervous system of the human body through electromagnetic wave energy.Moreover,electronic radiation can interfere with other electronic systems,leading to the malfunctioning of other electronic devices.Therefore,the development of effective electromagnetic wave absorption materials to prevent and control electromagnetic pollution is a pressing research topic.Currently,the most prevalent design strategy involves improving the impedance matching properties of absorption materials and endowing them with more loss mechanisms to meet the requirements of“lightweight,wide bandwidth,and strong attenuation ability”starting with structural design and component regulation.MoS₂,a typical transition metal dichalcogenide（TMD）,boasts an ultrathin layered structure,excellent electronic performance,and a large specific surface area,making it a sought-after material for high-quality absorption materials.Structural design and component regulation of MoS₂ can fully leverage the material’s loss mechanisms to attain excellent impedance matching characteristics and attenuation ability.This article specifically focuses on the attenuation mechanisms of MoS₂ in different systems to establish a universal framework for MoS₂ to attenuate electromagnetic waves.The primary research objectives are as follows:（1）Uniformly sized Cu-CuFe₂O₄ nanoparticles were prepared through a simple hydrothermal process,and CuFe₂O₄ nanoparticles were obtained by etching the Cu element with Fe³⁺through an oxidation-reduction reaction.A flower-like CuFe₂O₄/MoS₂composite was then created using a two-step hydrothermal method,which involved uniformly coating CuFe₂O₄ nanoparticles with MoS₂ nanoparticles.The crystal structure and micro-morphology of the material were characterized using XRD,Raman spectroscopy,and scanning and transmission electron microscopy.The structure and wave absorption properties of the CuFe₂O₄/MoS₂ composite were also investigated.The composite exhibits excellent impedance matching and electromagnetic wave absorption performance due to the synergistic effect of conduction loss,polarization loss（dipole polarization,interface polarization）,and magnetic loss（natural resonance and exchange resonance）.Specifically,the CuFe₂O₄/MoS₂ wave absorber demonstrates an effective absorption bandwidth（EAB）of 8.16 GHz（9.84 GHz～18 GHz）at 2.3 mm,which means that the wave absorber can effectively absorb the entire Ku band and some X-band electromagnetic waves.Additionally,the optimum reflection loss(RL_min)at 2.7 mm is-49.43 d B.（2）Structural engineering and component control are effective strategies for designing high performance electromagnetic wave absorbers.However,the challenge of understanding the structure-component-property relationship and developing efficient microwave absorbers remains a great challenge.In this section,we propose the use of microemulsion phase transitions to design dielectric absorbers with different structures.By adjusting the ratio of water and oil phases,three different structures of Mo O₂/C（MC）microspheres with solid,egg yolk shell and hollow structures can be prepared.And Mo O₂/MoS₂/C（MSC）trilayer dielectric microspheres with Schottky barrier were prepared by a subsequent vulcanization process,which achieved the control of interface and vacancy through component modulation.The analysis shows that the sensitivity of different structures to component modulation varies greatly,mainly in the number of vacancies generated during the vulcanization process.This difference is determined by the free space of the microspheres and the amount of effective medium.Among them,the RLmin of 50%sulfided Mo O₂/MoS₂/C yellow-shell microspheres（YSMSC）is-80.73d B at a thin thickness of 1.7 mm;the EAB of fully sulfided MoS₂/C hollow microspheres（HMSC）is 7.04 GHz at 2.2 mm.（3）Interfacial polarization is an important mechanism for the attenuation of electromagnetic waves in electromagnetic wave absorbers,but the degree of interfacial polarization contribution of absorbers is not clear today.We achieve the modulation of the interfacial type by adjusting the phase structure of the two-dimensional transition metal sulfide MS₂（M=Mo,V,W）,where 1T-MS₂ exhibits metallic properties and 2H-MS₂has semiconducting properties.Precise modulation of the interfacial polarization type can be achieved by changing the conductor properties of MS₂.In order to exclude the contribution of the intrinsic properties of a single MS₂ material,we investigated three TMDs that also possess phase transitions:MoS₂,VS₂,and WS₂.1T-MS₂（M=Mo,V,W）composites exhibit excellent electromagnetic wave absorption properties under the synergistic effect of conduction loss and interfacial polarization.1T-MoS₂/MOF-A exhibits the best electromagnetic wave absorption performance with RLmin of-61.07 d B at a thickness of 3.0 mm and EAB of 7.2 GHz at 2.3 mm.in addition,1T-VS₂/MOF-A has an EAB of 5.2 GHz at 2.1 mm and 1T-WS₂/MOF-A has an EAB of 5.84 GHz at 2.1mm.by The crystal structure as well as the microscopic morphology of the materials were characterized by XRD,Raman spectroscopy and scanning and transmission electron microscopy to establish the theoretical model of wave absorption of the composites from the microscopic level and to investigate the electromagnetic wave harvesting and absorption mechanism.