Preparation And Microwave Absorption Properties Of RGO/MWCNT/Fe₃O₄ Nanocomposites

In recent years,the development of electronic information technology is faster and faster.The technology brings us a lot of convenience in military and civil fields.The electromagnetic interference and radiation problems are also increased correspondingly.The problem of electromagnetic pollution has negative impact on the normal operation of electronic equipment,and it has a lot of potential damages to human health.Therefore,it is an effective way to solve the problem of electromagnetic pollution to develop effective microwave absorption?MA?materials.Graphene has been widely used in the field of MA materials,which owing to its characteristics of light weight,large specific surface area and adjustable relative complex dielectric constant.Carbon nanotubes have the characteristics of unique one-dimensional linear structure,which has a good bridging effect.And carbon nanotubes have been widely used in the field of MA materials too.Fe₃O₄ nanomaterial is one of the traditional ferrite-based MA materials,which has the advantages of simple preparation process,low cost and large-scale production.However,single-component material is difficult to meet the requirements of comprehensive properties of the current MA materials.In this paper,graphene,carbon nanotubes and Fe₃O₄ nanoparticles were combined to prepare carbon-based magnetic MA nanocomposite.By effectively regulating the electromagnetic parameters of the nanocomposite,the high efficiency of MA performances can be obtained.The main research contents were as follows:?1?Fe₃O₄ nanoparticles and MWCNT/Fe₃O₄?MFs?nanocomposites were synthesized via in situ one-pot solvothermal method.The effects of the content of Fe₃O₄ on the electromagnetic parameters and microwave absorption properties were investigated.When the content of Fe₃O₄ was 60 wt.%,the thickness of the sample was 5.5 mm,the reflection loss of Fe₃O₄ appears bimodal.The peakes position were at 5.8 GHz and 17.3 GHz respectively.The minimum reflection loss was-16.3dB,and the other reflection loss peak was-13.4 dB.The effective absorption bandwidth?RL <-10 dB?were 4.1-7.0 GHz and 17.0-18.0 GHz.The effects of the content of MWCNT of MWCNT/Fe₃O₄ nanocomposites on the electromagnetic parameters and microwave absorption properties were investigated.The MFs exhibited a minimum reflection loss?RL?value of-38.1 dB at 9.8 GHz with a thickness of 2.5 mm when the content of MWCNT was 6.4 wt.%.The RL values?<-10 dB?were observed to be in the range of 8.2-11.1 GHz.The effective microwave absorption bandwidth was tunable from 2.7 to 18 GHz by changing the sample thickness.?2?RGO/MWCNT/Fe₃O₄ nanocomposites?GMFs?were prepared by simple solvent thermal reaction.The effects of RGO content and reaction time on the electromagnetic parameters and MA performance of GMFs nanocomposites were studied.The GMFs exhibited a minimum reflection loss?RL?value of-61.29 dB at 10.5 GHz with a thickness of 2.6 mm when the contents of RGO and MWCNT were 6.3 and 1.3 wt.%,respectively.The RL values?<-10 dB?were observed to be in the range of 8.9-12.3 GHz,and the effective microwave absorption bandwidth was tunable from 3.5 to 18 GHz by changing the sample thickness.The results showed that the multi-interface,porous and multi-bridge structures of the composites are beneficial to the absorption of electromagnetic waves by the nanocomposites.Graphene,MWCNT and Fe₃O₄ have synergistic effects,and the combined effect of multiple loss mechanism can better improve the absorption efficiency of incident electromagnetic waves of nanocomposites.Furthermore,the absorption properties of nanocomposites can be regulated by the contents of MWCNT and RGO.The reaction time also had a certain influence on the MA properties of nanocomposites.Since no toxic solvents were used,this method is environmentally friendly.Moreover,it can be prepared in large quantity and has potential for large-scale production.The prepared MFs and GMFs may have a wide range of applications in microwave absorption materials against electromagnetic pollution.