Preparation And Microwave Absorbing Properties Of Fe Modified Molybdenum Selenide Nanocomposites

With the rapid development of information technology in the civilian and military fields,electromagnetic interference and pollution have become one of the key issues that needs to be resolved urgently all over the world.Therefore,researchers are dedicated to find"thin,light,wide,and strong"electromagnetic wave absorbing materials.Among many microwave absorbing materials,two-dimensional materials have a good response to electromagnetic waves,because induced electrons can transfer along the two-dimensional molecular network to form a dissipation current under the alternating electromagnetic field.Molybdenum diselenide has attracted the interest of researchers due to its special two-dimensional molecular structure and excellent intrinsic conductivity.Therefore,this work investigates the microwave absorption performance and mechanism of molybdenum diselenide,and then prepare MoSe₂-FeSe₂ and MoSe₂-Fe₂O₃ nanocomposites,respectively,to further improve its microwave absorption performance.This work used hydrothermal method to synthesize ultra-thin MoSe₂,and explored the influence of hydrothermal temperature and time on the morphology and microwave absorption properties.The experimental fingings show that the as-prepared MoSe₂ has ultra-thin and curly lamellar structure,increasing the transmission paths of the electromagnetic wave in the material.This leads to enhanced microwave loss.In addition,the phase composition of the as-prepared MoSe₂ is different.The existence of 1T phase in the as-prepared MoSe₂ increases the conductivity,leading to an increase in the current caused by carriers in the electromagnetic field of the material,which is conducive to the conversion of electromagnetic energy into thermal energy.The reflection loss of MoSe₂ synthesized at 200?and 20 h is-52.1 d B,when the matching thickness is 2.29mm at 13.36 GHz.In order to improve the microwave absorption performance of the material,a one-step hydrothermal method was used to prepare the MoSe₂-FeSe₂ nanocomposite by introducing an iron source.The as-prepared MoSe₂-FeSe₂ nanocomposite has a interface which contributes to enhance the dielectric loss of the material.Through XRD,SEM,Raman,TEM and BET analysis,the effects of morphology and phase on the microwave absorption properties of the material was studied.The as-prepared MoSe₂-FeSe₂ nanocomposite not only retains the lamellar structure,but also possesses interface between MoSe₂-FeSe₂,which enhances the dielectric loss.When Mo:Fe=1:1,the as-prepared MoSe₂-FeSe₂ nanocomposite has the best microwave absorption performance.At 13.92 GHz,when the matching thickness is 1.71 mm,the reflection loss of the material is-52.26 d B.Importantly,compared with ultra-thin MoSe₂,the matching thickness of the material is significantly reduced.In order to explore the influence of magnetic loss on material properties,MoSe₂-Fe₂O₃ nanocomposite was synthesized by a two-step hydrothermal method.The introduction of Fe₂O₃ not only enhances the interface loss of the material,but also introduces magnetic loss.As a result,the as-prepared MoSe₂-Fe₂O₃ nanocomposite presents the improved impedance matching condition and enhances the microwave absorption performance.When MoSe₂:Fe₂O₃=4:1,the reflection loss is-56.14 d B at 12.72 GHz when the matching thickness is 1.63 mm.Even at lower matching thickness of 1.2 mm,the reflection loss is-52.14 d B at 16.96 GHz.Therefore,the effective absorption width of the material reaches about 4 GHz.The introduction of Fe₂O₃ contributes natural resonance and eddy current loss to the microwave absorption.