Preparation And Electromagnetic Interference Shielding Properties Of Ti₃C₂T_x And Core@shell Structured Ti₃C₂T_x@Ni Particles

Ti₃C₂T_x MXene,a new type of two-dimensional(2D)nanomaterial with high conductivity,high specific surface area,good hydrophilic character,and excellent electrochemical performance,is one of the most promising 2D nanomaterials after graphene,and has wide applications in the fields of supercapacitors,batteries,electromagnetic shielding and stealth.At present,acid etching of Ti₃Al C₂ is commonly used to obtain 2D Ti₃C₂T_x,but long preparation time limits its applications.In the present study,process parameters were optimized to shorten the preparation time,and thermal stability and electromagnetic(EMI)shielding performance of Ti₃C₂T_x were investigated.In addition,electroless plating technology was adopted to modify Ti₃C₂T_x.A core@shell structured Ti₃C₂T_x@Ni with excellent electromagnetic shielding performance was successfully obtained.By studying the relationship between the electrical conductivity,magnetic properties and electromagnetic parameters of the modified powder and the electromagnetic shielding performance,the electromagnetic shielding mechanism was revealed.This article has achieved the following innovative results:(1)The optimized conditions for preparing Ti₃C₂T_x were determined by systematically studying the influences of etching solution concentration,etching temperature and time on the etching effect of Ti₃Al C₂.The results showed that 2D Ti₃C₂T_xcan be successfully obtained by etching of 200 mesh Ti₃Al C₂ for only 0.5 h at 50°C in40 wt.%HF acid solution.This is the shortest time for preparing Ti₃C₂T_x in the reported literature.(2)Thermal stability of Ti₃C₂T_x in air and vacuum atmospheres was studied to confirm its application temperatures.In air condition,Ti₃C₂T_x is stable to 300°C;at above this temperature,it will be oxidized to Ti O₂.Ti₃C₂T_x has better stability under vacuum condition,stable up to 800°C.But it will gradually undergo a phase transformation as the temperature exceeds 800°C.(3)A core-shell structured Ti₃C₂T_x@y Ni(y=10-80 wt.%)powder with adjustable Ni content was obtained by optimization of electroless Ni plating process.Among them,Ti₃C₂T_x@80Ni has the best magnetic properties,electrical conductivity and EMI shielding efficiency.When the content of Ti₃C₂T_x@80Ni in paraffin wax was up to 80wt.%,its electrical conductivity and EMI shielding effectiveness were 19338.8 S/m and74.14 d B,respectively,greatly higher than those of Ti₃C₂T_x with the same content.(4)The EMI shielding mechanism of Ti₃C₂T_x@Ni/wax is mainly the absorption loss,together with the reflection loss.Compared with pure Ti₃C₂T_x,the improvement of EMI shielding performance of Ti₃C₂T_x@Ni is due to the significant improvement of conductivity and the introduction of multiple magnetic loss mechanisms.In addition,the formation of a large number of Ti₃C₂T_x/Ni heterogeneous interfaces also contributes to the improvement of EMI wave dissipation through the interface polarization and the multiple reflection loss.