Ti₃C₂T_x/Fe₃O₄ Nanocomposites For Highly Enhanced Electromagnetic Properties

Electromagnetic wave has been widely used in the fields of electronics,communication and national defense.At the same time,the popularity of electromagnetic wave also brings many problems such as electronic pollution and electromagnetic interference.Therefore,the preparation of electromagnetic wave absorbing or shielding materials with superior performance is of great significance to improve the living environment,maintain national security and protect human health.Due to the unique layered structure,high specific surface area,good mechanical and dielectric properties,Ti₃C₂T_x MXene has attracted more and more attention in the field of electromagnetic wave absorption and shielding.The response characteristics of Ti₃C₂T_x MXene with different spatial configurations to electromagnetic waves are still unclear,and there is still much room to optimize the electromagnetic wave absorption or shielding properties of Ti₃C₂T_x MXene based materials.In this paper,multilayer Ti₃C₂T_x MXene(m-Ti₃C₂T_x)and fewlayer Ti₃C₂T_x(f-Ti₃C₂T_x)with different morphologies were prepared by different etching methods.Then,Fe₃O₄/m-Ti₃C₂T_x and Fe₃O₄/f-Ti₃C₂T_x nanocomposites were prepared by hydrothermal method,ultrasonic dispersion and mechanical stirring method,respectively.Meanwhile,the morphology and composition of the nanocomposites were adjusted appropriately,the electromagnetic wave absorption and shielding properties of the composites were studied,and the mechanism of electromagnetic wave absorption and shielding was explored.The specific research contents and results are as follows:(1)M-Ti₃C₂T_x with uniform layer structure was prepared by HF solution etching Ti₃Al C₂ powder,and the layer structure was preserved by freeze-drying technology.Then,m-Ti₃C₂T_x/Fe₃O₄ nanocomposites with different morphologies were prepared by simple solvothermal method.The nucleation and growth mechanism of Fe₃O₄ in the interlayer and surface of Ti₃C₂T_x were analyzed.The results show that m-Ti₃C₂T_x/Fe₃O₄ nanocomposites exhibit better electromagnetic wave absorption properties than single Ti₃C₂T_x MXene and pure Fe₃O₄ nanoparticles.Among the four composites with different components,the performance of sample S2 is the best,and the minimum return loss(RL)is-50.48 d B(10.18 GHz),and the thickness of the absorber is only 1.7 mm;at the same time,the effective absorption band(EAB)reaches3.2 GHz when the thickness of the absorber is 1.3 mm.The good electromagnetic wave absorption properties of sample S2 are attributed to its unique layered structure,excellent conductivity,a large number of dipole polarization and interface polarization,and the synergistic loss effect caused by various loss mechanisms.(2)F-Ti₃C₂T_x with thin,translucent and good mechanical properties was prepared by Li F and HCl solution etching and ultrasonic dispersion.Then,f-Ti₃C₂T_x/Fe₃O₄nanocomposites with different morphologies were prepared by ultrasonic dispersion and mechanical stirring.Compared with pure phase f-Ti₃C₂T_x,the improvement of electromagnetic wave absorption performance of the f-Ti₃C₂T_x/Fe₃O₄ nanocomposites is not obvious,and the minimum reflection loss is less than-15 d B,which is mainly due to the mismatch between the absorber and free space impedance caused by the high dielectric constant of f-Ti₃C₂T_x,which leads to the reflection of most electromagnetic waves on the external surface of the absorber.However,the electromagnetic wave shielding performance of the composite has been greatly improved.When the coating thickness is 2.6 mm,the average electromagnetic interference shielding effectiveness(SE_total)of the sample S3 reaches 62.19 d B,and the maximum SE_total reaches 68.72 d B at 18 GHz,which has the potential to become an excellent electromagnetic wave shielding material.In conclusion,the electromagnetic properties of Ti₃C₂T_x MXene can be effectively improved by adjusting the micro morphology of Ti₃C₂T_x MXene and introducing magnetic materials.Therefore,this paper can provide a new idea for the preparation of excellent mxene based electromagnetic wave absorbing and shielding materials.