2D/2D MoS₂/Ti₃C₂T_x-based Nanocomposites For Enhanced Microwave Absorption Properties

With the development of science and technology,the military and civilian fields have more and more urgent demands for lightweight,wide-band,and strong-absorbing new microwave absorption materials.Two-dimensional nanomaterials have the characteristics of large specific surface area,adjustable surface chemical groups,and rich functional groups,which have become a hot spot in the current research on microwave absorbing materials.In this paper,a series of "thin,light,wide and strong" nanocomposite absorbers are obtained by adjusting the composition ratio of MoS₂ and Ti₃C₂T_x,introducing the third phase,and microwave-assisted heating.The main content and research results are as follows:(1)Ti₃C₂T_x material was prepared by traditional hydrofluoric acid etching method.The MoS₂ nanosphere structure and TiO₂/Ti₃C₂T_x layered structure nanocomposites were obtained under hydrothermal conditions at 200 ? for 15 h,respectively.MoS₂-60wt% composites exhibit microwave absorbing performance with an effective absorbing bandwidth of 1.8 GHz at 3.0 mm and an optimal reflection loss of-11.2 d B.(2)MoS₂/TiO₂/Ti₃C₂T_x composites with different MoS₂ contents were prepared using the above hydrothermal conditions.It was found that MoS₂ nanosheets were grown vertically between Ti₃C₂T_x layers and on the surface,and TiO₂ crystals were mainly distributed at the edges of the layers.When the theoretical mass ratio of MoS₂ to Ti₃C₂T_x is 1:1 and the mass fraction of MoS₂/TiO₂/Ti₃C₂T_x composite material is60wt%,the lightweight absorbing material with thin coating(1.0 mm),wide band(3.0GHz)and strong absorption(-30.7 d B)is obtained.This excellent absorbing performance can be explained in terms of structure,impedance matching,and microloss mechanism.The multilayer structure of Ti₃C₂T_x can give rise to multiple reflection and scattering of incident waves.MoS₂ and TiO₂ optimize impedance matching,form a large number of defects and heterogeneous interfaces,strengthen the behavior of dipole polarization and interface polarization,and then enhance the polarization loss.At the same time,the conduction loss of Ti₃C₂T_x also plays an important role.(3)C/MoS₂/Ti₃C₂T_x composites were prepared by one-step hydrothermal method.When the added amount of D-glucose is 200 mg,the specific performance of C200 is as follows: at a thickness of 1.5 mm,the minimum reflection loss is-42.7 d B;at a thickness of 1.0 mm,its effective absorbing bandwidth reaches 3.2 GHz.Comprehensive analysis shows that the surface modification of carbon nano-plating can effectively enhance the conductance loss,induce dipole and interface polarization,multiple reflection absorption and other mechanisms,thereby significantly improving the microwave absorption performance.(4)Since the conventional hydrothermal method is time-consuming and Ti₃C₂T_x is prone to oxidation,MoS₂/Ti₃C₂T_x composites were rapidly prepared by microwaveassisted hydrothermal technique with 800 W power and 200 ? hydrothermal condition with 30 min holding time.When the theoretical mass ratio of MoS₂ to Ti₃C₂T_x is 6:1,the material has the best absorbing performance: when the thickness is 2.0 mm,the reflection loss extreme value reaches-41.5 d B,and the bandwidth is 3.6 GHz.