Preparation And Properties Of Flower-Like Electromagnetic Wave Absorbing Composite Materials Based On MXene

The rapid development of wireless technology,especially electronic equipment or artificial intelligence,provides us with a convenient life,but also causes more and more electromagnetic wave pollution,therefore,can provide physical protection and equipment anti-interference electromagnetic wave absorption materials become more and more urgent.However,it is difficult for a single component electromagnetic wave absorbing material to achieve the requirements of"wide,light,thin and strong".Therefore,this paper focuses on the design of multi-component electromagnetic wave absorbing material and the design of its morphology,so that the composite material can show good electromagnetic wave absorption characteristics.In this paper,two kinds of electromagnetic wave absorbing materials have been designed successively,and a series of Ti₃C₂T_x MXene based composite absorbing materials have been prepared by hydrothermal method and electrospinning method,and their structure and properties have been studied.Firstly,in Chapter 3,a series of ZnO/TiO₂/Ti₃C₂T_x MXene composite wave absorbent materials with special regular flowers were prepared by self-assembly using a simple hydrothermal method,and their structure and morphology were characterized.The results show that the content of Ti₃C₂T_xand the optimal growth direction of ZnO determine the formation of different special morphologies,and the introduction of TiO₂and the construction of three-dimensional layered micro-nano structures with multiple interfaces can obviously optimize the impedance matching.The unique three-dimensional flower morphology and the heterogeneous interface,high specific surface area,local sag and functional groups generated by the multi-petal layer structure as well as partially oxidized TiO₂are the main reasons for the polarization loss and dipole loss of the material to the electromagnetic wave.The introduced multi-components make the composite show excellent electromagnetic wave absorption performance.When the thickness is 2.5mm and 8.8 GHz,The RL_minvalue can reach-31.96d B,and the corresponding effective bandwidth is 1.4GHz when RL≤-10d B.The flower-like ZnO/TiO₂/Ti₃C₂T_x MXene composites have better electromagnetic wave absorption ability at relatively thin thickness.Although ZnO/TiO₂/Ti₃C₂T_x MXene composite has excellent electromagnetic wave absorption performance,its absorption bandwidth is narrow,which is difficult to meet the requirements of"wide,light,thin and strong"electromagnetic wave absorption materials.Therefore,porous carbon nanofiber materials are introduced in Chapter 4.The electromagnetic wave absorbing materials are further studied from the aspects of composition and morphology design.In this chapter,porous carbon nanofibers were obtained by electrospinning method,and the composite of porous carbon nanofibers with ZnO/TiO₂/Ti₃C₂T_x MXene was continued by hydrothermal method in Chapter 3 to prepare porous carbon nanofibers@ZnO/TiO₂/Ti₃C₂T_x MXene composites with 3D mesh and flower structure.The porous structure can increase the reflection and scattering effect of electromagnetic wave in porous media,and the high specific area,high porosity and special three-dimensional connection network of nanofibers make them have low density while maintaining a certain conductivity,which is conducive to obtaining good impedance matching.The combination of ZnO/TiO₂/Ti₃C₂T_x MXene and porous carbon nanofibers can construct a multi-layer and multi-interface three-dimensional structure,further enhance the reflection,polarization loss and dielectric loss of electromagnetic wave of the composite material,and then improve the absorption performance of electromagnetic wave,so that electromagnetic wave can better enter the material.The effective absorption bandwidth of@ZnO/TiO₂/Ti₃C₂T_x MXene with 3D mesh-flower structure is 13.95GHz for ZTC5,8.39GHz for ZTC16 and 10.3GHz for ZTC45.The effective absorption range is greater than 8GHz.The thickness of ZTC5is 3mm,the RL_minat 8.73 GHz is-39.45 GHz,and the effective bandwidth is 3.86GHz.When the thickness of ZTC5 is only 2mm,its effective absorption bandwidth can reach 6.1 GHz,accounting for 38.13%of the whole absorption band.When the thickness of ZTC16 is 5mm,the RL_minis-42.27 GHz and the effective bandwidth is2.25 GHz at 3.98GHz.The thickness of ZTC45 is 4mm,the RL_minat 5.26 GHz is-23.75 GHz,and the effective bandwidth is 2.8 GHz.By comparison,it can be judged that ZTC5 has the best wave-absorbing performance.After the addition of carbon fiber,the network structure carried by carbon nanofibers and the layered nanoflowers grown on the surface contribute to the scattering and reflection of incident electromagnetic wave,which helps to broaden the transmission path of electromagnetic wave.Moreover,the addition of carbon nanofibers can also enhance the dielectric loss ability.Its multi-interface porous structure helps to improve impedance matching and thus enhance electromagnetic wave absorption.A series of flower-like Ti₃C₂T_x MXene based absorbing materials prepared in this work is a kind of excellent electromagnetic wave absorbing materials.The exploration and construction of its structure system has certain inspiration for the design and preparation of new absorbing materials.