Preparation And Wave Absorbing Property Of Graphene Based Sulfide Composites

Nowadays,with the rapid development of information technology,various electronic devices have become an integral part of our life and are closely related to our life.However,these convenient devices also bring us inRCeasingly serious electromagnetic wave pollution when they make our life better,which not only infects our life and production,but also endangers our healthy.The effective way to solve electromagnetic pollution problem is electromagnetic wave absorbing material.But,at present,the most important problems is that the density of electromagnetic wave absorbing materials is large and the effective absorbing bandwidth is narrow.As a new type of electromagnetic wave absorbing material,transition metal sulfide has shown its excellent performance.However,it has the problem of high filling amount in the matrix and narrow effective absorption bandwidth.In this paper,the coating structure of cobalt sulfide and zinc sulfide with graphene was studied to improve the absorption performance of electromagnetic waves.The main research contents are as follows:(1)Graphite oxide was prepared by chemical method and reduced by hydrazine hydrate.RGO sheets were successfully obtained.The morphology and structure of graphene were observed by SEM and TEM.The results showed that before reduction,the graphene sheets were relatively thick and stacked together.After reduction,the graphene sheets were transparent and showed obvious folds.This indicates that graphite oxide has been successfully reduced to graphene.Graphene/paraffin composite ring samples were prepared by mixing graphene with paraffin to study its electromagnetic absorption performance.The vector network analyzer was used to simulate the reflection loss of the material when the filling amount of graphene was 5%,10%,15% and 20% and the thickness was 2 mm and 3mm.The results show that when the filling amount is 15%,it has the best absorbing performance.When the thickness is 3 mm,the reflection loss peak at 7.9 GHz is-20 dB,and the absorption bandwidth below-10 dB is 3.7 GHz.In addition,graphene coatings were prepared,and the measured reflection loss of 2mm and 3mm coating was studied when the graphene content was 5%,10%,15% and 20%.The results show that the measured reflection loss is blew to the simulated electromagnetic wave performance.Moreover,when the filling amount is 15% and the thickness is 2mm,the maximum reflection loss is-18.2dB and the absorption bandwidth below-10 dB is 2.8GHz when the reflection loss is less than-10 dB.(2)The graphene coating cobalt sulfide(CoS@RGO)composite miRCospheres obtained and the morphology and chemical composition were studied by SEM,TEM and Raman characterization methods,the results show that the CoS@RGO is three-dimensional(3D)flower structure and the surface has a thin layer structure,using the vector network analyzer to test the absorbing performance of graphene with the different concentration coated CoS.The result shows that the concentration of 0.8 mg/mL graphene coated CoS@RGO composite material has the best effect of absorbing,After further study in paraffin matrix with different filling amounts(15%,20%,25%,30%),the results show that when the filling amount is 20%,the miRCowave absorption performance of the composite material is the best,the reflection loss value at 12.1 GHz is-36.5dB,and the thickness is 2.0 mm.In addition,the material has an excellent absorption bandwidth of 12.5GHz(4.7-17.2 GHz)(the reflection loss is lower than-10dB).(3)The ZnS miRCospheres was prepared by the hydrothermal method successfully,and coted it with a layer of graphene on the surface,and use XRD,SEM,TEM and XPS characterization methods characterizing the morphology and chemical composition of the material,the results showed that zinc sulfide graphene composites(ZnS@RGO)have the coated structure,there are many convex part on the surface of zinc sulfide,whit the diameter about 400 nm and relatively uniform size distribution.The ZnS@RGO composite was mixed with paraffin in different filling amounts(15%,20%,25%,30%)to produce ring samples,which were tested by the coaxial method to obtain the electromagnetic parameters of the material and its corresponding simulated reflection loss.The results show that the ZnS@RGO composite can achieve the best absorbing performance when the coating thickness is 2 mm and the filling amount is 30%.At 11.2 GHz,the maximum reflection loss reaches to-21 dB,and the bandwidth below-10 dB is 2.5 GHz...