Preparstion And Electromagnetic Interference Shielding Properties Of Lightweight Graphene And MXene Aerogels

The increasing of electromagnetic pollution has seriously affected human health and the normal function of precision electronic systems.With the rapid development of the aerospace industry,electromagnetic interference shielding materials are moving toward lighter and higher performance.The development technology of electromagnetic interference shielding materials in our country is very slow,especially in the aerospace field,the stealth shielding technology lags far behind the western developed countries,so the production of lightweight and high-performance electromagnetic interference shielding materials is extremely urgent.In this paper,a lightweight aerogel was constructed based on graphene oxide and a new two-dimensional material MXene.The electromagnetic interference shielding performance of the prepared material was investigated in detail:In this paper,a large single layer graphene oxide which was prepared by modified methods of Hummers,and then add pyrrole and hydrogen peroxide to the graphene oxide solution,using a simple hydrothermal method,freeze-drying technology and heat treatment methods to prepare the light porous structure of graphene aerogels.In the hydrothermal process,hydrogen peroxide can etch nano-scale pores on the surface of graphene oxide.After heat treatment,the decomposition of polypyrrole can make N element doping into graphene,thus further promoting the conductivity of the resulting graphene aerogel.With the increase of the amount of pyrrole,the volume of aerogels increased,and the electromagnetic interference shielding effectiveness of aerogels increased at the same time.When the amount of pyrrole added to 50?L,the electromagnetic interference shielding performance of graphene aerogel can reach 23.3dB at 8.2 GHz.The methods of direct hydrofluoric acid etching and in-situ hydrofluoric acid etching for the preparation of high quality MXene were studied.The effects of etching time and reaction temperature on the quality of the final product were discussed.It was finally shown that in-situ hydrofluoric acid etching method can produce high-yield and low-defect single-layer MXene,and the MXene sheet size reaches the micron level.Then,the MXene films prepared by in-situ hydrofluoric acid method were tested for electromagnetic interference shielding performance.The results show that the electromagnetic interference shielding performance of the prepared MXene films increase with the thickness.And when the MXene films thickness are 8?m,the electromagnetic interference shielding effectiveness of the material can reach as high as60 dB,the amount of attenuation is up to 99.9%,and the SSE/t value is up to 19531.1cm² g^-1,this value is significantly better than most current literature reported on electromagnetic interference shielding materials.By using the characteristics that graphene oxide sheets are easily overlapped to form aerogels,graphene oxide is introduced into the MXene system,and a composite aerogel with a three-dimensional network structure of MXene and graphene is designed.The density of composite aerogels decreases with the increase of graphene oxide,but the electrical conductivity decreases and the electromagnetic interference shielding performance also decreases significantly.When the mass ratio of GO to MXene was 1:1,the conductivity of MX-rGO_1:1:1 composite aerogels was as high as 1250 S m^-11 with the density is only 7.2 mg cm^-3.Moreover,the electromagnetic interference shielding effectiveness of the composite aerogels at 8.2 GHz are 30.6 dB,and up to 50 dB at 12.4GHz.In addition,the SSE/t of MX-rGO_1:1:1 is as high as 4166 cm³ g^-11 at 8.2 GHz,which is far superior to most of the electromagnetic interference shielding materials that have been reported.