| In the 21 st century,wireless communication equipment plays an important role in people’s life.Accompanied with the rapid development of various electronic devices,electromagnetic pollution has been becoming a serious environmental issue,which will cause data loss,system failure even threaten human health etc.Electromagnetic interference(EMI)shielding materials have been extensively developed to avoid undesirable electromagnetic radiation,which can cut off the transmission of electromagnetic waves.However,with the miniaturization and diversification of information equipment,traditional EMI shielding materials(such as metals,etc.)can no longer meet the demand of miniaturization and lightweight.Thus,exploring excellent EMI shielding materials with ultrathin,lightweight,high-strength,and flexible has become an emergent topic for the development of information technology.The MXene with two-dimensional layered structure has been considered as a promising EMI shielding material because of its excellent electrical conductivity,large specific surface area and excellent processability.Recently,much efforts have been devoted to improving the conductivity of materials for superior electromagnetic shielding effectiveness.But this way will be limited by the intrinsic properties of the material.Therefore,a key issue is to improve the shielding performance furtherly for the development and application of MXene.Herein,we optimize the EMI shielding performance of MXene by material design in microscale,nanoscale,and atomic-scale,which enhance the absorption attenuation of electromagnetic waves.The details are demonstrated in the following:(1)Microscale structures are constructed for optimizing electromagnetic shielding efficiency.MXene sheets are adhered to the three-dimensional fiber surface of the non-woven fabric by chemical impregnation.The microscale holes can be formed by the interlacement of fibers,where multiple reflection interfaces are induced after adhesion of conductive MXene sheets.Such a structure can increase the loss of electromagnetic waves by reflection,scattering and interference phase cancellation.Thus,the method of constructing microscale three-dimensional structures increases the attenuation efficiency of electromagnetic waves by increasing the structural loss of materials.It provides a new idea for the efficient shielding materials.(2)Nanoscale defects are introduced to achieve superior electromagnetic shielding performance.Defects and dislocations are introduced into MXene nanosheet by acid corrosion method.With the increase of defects and dislocation concentration,internal stress will gather in MXene film,which will induce the formation of non-artificial wrinkles.KPFM and first-principles calculations show that electric dipoles can be formed on the surface of the film after the formation of wrinkles,and these electric dipoles greatly enhance the absorption of incident electromagnetic waves.Then,the accumulation of wrinkled film is used to enhance the absorption of electromagnetic waves by electric dipoles for achieving excellent electromagnetic shielding efficiency at a small thickness.This work provides a new way for designing highly efficient electromagnetic shielding materials.(3)Atomic-scale doping is introduced to regulate the absorption peak of electromagnetic waves.Single atoms are incorporated into the MXene material by costirring.Atomic-scale intrinsic vacancies will be introduced into the material inevitably in the process of chemical etching,where we can incorporated single atom by stirring the solution of MXene and metal cation salt.We found that the resulting electromagnetic shielding material has different absorption peaks by regulating the types of doped atoms.This work provides a design idea for the controllable absorption frequency and broadband absorption performance of shielding materials. |
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