Preparation Of Three-dimensional Reduced Graphene Oxide Composite Material And Research Of Its Microwave Absorption Properties

In the civil and military fields,there is an urgent need to develop the electromagnetic wave absorption materials with good absorption effects and superior physical properties.Reduced graphene oxide(RGO)inherits the excellent physical properties of graphene.At the same time,its residual defects and oxygen-containing groups can effectively improve the impedance matching and enhance the polarization loss.Therefore,RGO is considered to have a strong application prospect in the field of microwave absorption.The two-dimensional RGO sheets are further stacked into a three-dimensional porous structure,which can become a framework for other materials to adhere to,bringing better absorbing effects.In this paper,three-dimensional RGO/PANI aerogel and three-dimensional reduced graphene oxide/iron@carbon are prepared by attaching sheet-shaped polyaniline(PANI)and iron/carbon nanobox(Fe@C)to graphene sheets,respectively.and theirs morphology,structure and electromagnetic properties have been studied.Then,using the successfully prepared RGO/PANI and RGO/Fe@C as the filler of the plate layer,a new type of double-layer absorber was designed,and its reflection loss and absorption mechanism are studied through software simulation.The specific research content is as follows:(1)RGO/PANI aerogel is prepared by a two-part self-assembly method.PANI nanosheets are evenly distributed on the RGO framework and form a PANI conductive network,expanding the conductive path of carriers.With the increase of PANI content in the RGO/PANI aerogel,the microwave absorption performance of the composite shows a trend of first enhancement and then deterioration.The change in conductivity is the main factor leading to this trend.The optimized RGO/PANI aerogel achieves the best absorption loss of-48 d B at a load of only 3% and the qualified absorption bandwidth covers the entire of 12-18 GHz.(2)The three-dimensional RGO/prussian blue precursor is prepared by a one-pot method.After further pyrolysis,the RGO/Fe@C aerogel was finally prepared.After pyrolysis,the organic ligands in Prussian blue are graphitized,and the iron ions and ferrous ions are reduced to iron.Finally,Prussian blue is transformed into Fe@C nanobox with a hollow cubic structure.Under the synergistic effect of the dielectric loss of three-dimensional graphene and the magnetic loss of elemental iron,the RGO/Fe@C composites material have achieved good impedance matching and electromagnetic attenuation capability.In this paper,the changes in the appearance and electromagnetic properties of RGO/Fe@C aerogels are explored by adjusting the amount of Fe@C in the composites.Finally,the minimum reflection loss of RGO/Fe-2 at a thickness of 2.5 mm is-43.5 d B.(3)Using the successfully prepared RGO/PANI aerogel and RGO/Fe@C aerogel as the sheet filler,a new type of the double-layer absorption coating is designed.According to the software simulation results,when the RGO/Fe@C aerogel(the weight ratio is 3%)is used as the matching layer with the thickness of 0.5 mm,and the RGO/PANI aerogel(the weight ratio is 3%)is used as the absorption layer with the thickness of 1.8 mm,the double-layer absorption coating achieves the best microwave absorption.Through the analysis of the absorption mechanism,it is found that the power loss is concentrated in the matching layer and the attenuation mechanism is mainly the dielectric loss.