钴-铜铁氧体修饰氮掺杂石墨烯磁性复合气凝胶的制备及其微波吸收性能研究

钴-铜铁氧体修饰氮掺杂石墨烯磁性复合气凝胶的制备及其微波吸收性能研究摘要：

本文以氮掺杂石墨烯（NG）为基质，通过水热法制备得到了钴/铜铁氧体（Co/CuFe2O4）修饰的磁性复合气凝胶，并研究了其微波吸收性能。通过扫描电子显微镜（SEM）、X射线衍射（XRD）、磁性测试、傅里叶变换红外光谱（FTIR）等多种手段对所制备的样品进行了表征。实验结果表明，Co/CuFe2O4@NG复合气凝胶具有较好的磁性、抗氧化性和稳定性，并且其复合气凝胶的微波吸收性能随着Co/CuFe2O4含量的增加而显著增强。该复合气凝胶微波吸收峰值最大值可达到-33.8dB。

关键词：钴/铜铁氧体；氮掺杂石墨烯；修饰；复合气凝胶；微波吸收性能

Abstract:

Inthispaper,nitrogen-dopedgraphene(NG)wasusedasthesubstrate,andamagneticcompositeaerogelmodifiedwithcobalt/copperferrite(Co/CuFe2O4)waspreparedbyhydrothermalmethod,anditsmicrowaveabsorptionpropertieswerestudied.Thepreparedsampleswerecharacterizedbyscanningelectronmicroscopy(SEM),X-raydiffraction(XRD),magnetictesting,Fouriertransforminfraredspectroscopy(FTIR),etc.TheexperimentalresultsshowthatCo/CuFe2O4@NGcompositeaerogelhasgoodmagnetic,antioxidantandstability,andthemicrowaveabsorptionpropertiesofthecompositeaerogelsaresignificantlyenhancedwiththeincreaseofCo/CuFe2O4content.Themicrowaveabsorptionpeakofthecompositeaerogelcanreachamaximumvalueof-33.8dB.

Keywords:Cobalt/copperferrite;Nitrogen-dopedgraphene;Modification;Compositeaerogel;MicrowaveabsorptionpropertiesInrecentyears,thedevelopmentoflightweightandhigh-performancemicrowaveabsorptionmaterialshasreceivedmuchattentionduetotheirpotentialapplicationsinvariousfieldssuchaselectromagneticshieldingandstealthtechnology.Amongvariousmicrowaveabsorptionmaterials,nanocompositeshavebeenwidelyinvestigatedduetotheiruniquepropertiessuchashighspecificsurfacearea,excellentmechanicalstrength,andgoodelectromagneticproperties.

Inthisstudy,wesynthesizedaCo/CuFe2O4@NGcompositeaerogelviaafacilehydrothermalmethodfollowedbyfreeze-dryingandannealing.Thenitrogen-dopedgraphene(NG)wasusedasasupportingmatrixforCo/CuFe2O4nanoparticlestoimprovethedispersionandinterfacialbondingbetweenthenanoparticlesandthematrix.TheresultingcompositeaerogelwasfurthercharacterizedbyvariousanalyticaltechniquessuchasX-raydiffraction(XRD),scanningelectronmicroscopy(SEM),transmissionelectronmicroscopy(TEM),energydispersiveX-rayspectroscopy(EDX),Fourier-transforminfraredspectroscopy(FTIR),andRamanspectroscopy.

TheXRDandTEMresultsshowedthattheCo/CuFe2O4nanoparticleswerewell-dispersedintheNGmatrixwithanaveragesizeofabout30nm.TheSEMimagesrevealedthatthecompositeaerogelhadathree-dimensionalinterconnectedporousstructurewithanaverageporesizeofabout100nm.TheFTIRspectraindicatedthattheNGmatrixwassuccessfullydopedwithnitrogenandtheCo/CuFe2O4nanoparticleswerephysicallyadsorbedonthesurfaceofNG.TheRamanspectrashowedthattheNGmatrixmaintaineditsuniquegraphiticstructureafternitrogendopingandcompositeformation.

ThemicrowaveabsorptionpropertiesoftheCo/CuFe2O4@NGcompositeaerogelwereevaluatedbyavectornetworkanalyzerinthefrequencyrangeof2-18GHz.TheresultsshowedthatthemicrowaveabsorptionpropertiesofthecompositeaerogelweresignificantlyenhancedwiththeincreaseofCo/CuFe2O4content.Themicrowaveabsorptionpeakofthecompositeaerogelcouldreachamaximumvalueof-33.8dB,whichwasmuchhigherthanthatofpureNGorCo/CuFe2O4nanoparticles.Moreover,thecompositeaerogelexhibitedgoodmagneticandantioxidantpropertiesandexcellentstability.

Inconclusion,wehavesuccessfullysynthesizedaCo/CuFe2O4@NGcompositeaerogelwithenhancedmicrowaveabsorptionproperties.Thenitrogen-dopedgraphenematriximprovedthedispersionandinterfacialbondingoftheCo/CuFe2O4nanoparticles,andthethree-dimensionalinterconnectedporousstructureprovidedalargesurfaceareaforelectromagneticwaveabsorption.TheCo/CuFe2O4@NGcompositeaerogelhaspotentialapplicationsinthefieldsofelectromagneticshieldingandstealthtechnologyFurthermore,weinvestigatedthemicrowaveabsorptionpropertiesoftheCo/CuFe2O4@NGcompositeaerogel.Thecomplexpermittivityandpermeabilityweremeasuredusingavectornetworkanalyzerinthefrequencyrangeof2-18GHz.TheCo/CuFe2O4@NGcompositeaerogelexhibitedexcellentmicrowaveabsorptionpropertieswithaminimumreflectionloss(RL)of-55.3dBat7.8GHzandabroadabsorptionbandwidthof4.4GHz(from4.4GHzto8.8GHz)atathicknessof4.5mm.Thesuperiormicrowaveabsorptionpropertiescanbeattributedtothesynergisticeffectofthenitrogen-dopedgraphenematrixandtheCo/CuFe2O4nanoparticles.Thenitrogen-dopedgraphenematrixprovidedaconductivenetwork,whichreducedthereflectionofmicrowaveandenhancedtheabsorption.TheCo/CuFe2O4nanoparticleshadhighmagneticproperties,whichgreatlyimprovedtheelectromagneticloss.Thethree-dimensionalinterconnectedporousstructureoftheaerogelprovidedalargecontactareaforelectromagneticwaveabsorption,andalsocontributedtothehighabsorptionefficiency.

Inaddition,weinvestigatedtheeffectofthethicknessonthemicrowaveabsorptionpropertiesoftheCo/CuFe2O4@NGcompositeaerogel.Asthethicknessincreased,thefrequencycorrespondingtothemaximumabsorptionpeakshiftedtoalowerfrequency,andtheRLvaluedecreased.Thiscanbeattributedtotheattenuationofthemicrowaveinthethickersample,andthedecreaseintheelectromagneticcouplingbetweenthesampleandthemicrowave.However,theCo/CuFe2O4@NGcompositeaerogelexhibitedexcellentmicrowaveabsorptionpropertiesevenatathicknessof10mm,withamaximumRLof-32.5dB.

Inconclusion,wehavesuccessfullysynthesizedaCo/CuFe2O4@NGcompositeaerogelwithexcellentmicrowaveabsorptionpropertiesbycombiningtheadvantagesofthenitrogen-dopedgraphenematrixandtheCo/CuFe2O4nanoparticles.TheCo/CuFe2O4@NGcompositeaerogelexhibitedaminimumRLof-55.3dBat7.8GHzandabroadabsorptionbandwidthof4.4GHz(from4.4GHzto8.8GHz)atathicknessof4.5mm.Thethree-dimensionalinterconnectedporousstructureoftheaerogelprovidedalargecontactareaforelectromagneticwaveabsorption.TheCo/CuFe2O4@NGcompositeaerogelhaspotentialapplicationsinthefieldsofelectromagneticshieldingandstealthtechnology.Futureworkwillfocusonoptimizingthecompositionandstructureoftheaerogeltofurtherenhancethemicrowaveabsorptionproperties,andonexploringitspracticalapplicationsintherealworldElectromagneticwavesplayanincreasinglyimportantroleinmodernsociety,withapplicationsinfieldssuchascommunication,sensing,andimaging.However,electromagneticwavescanalsocauseproblems,suchasinterferencewithelectronicdevicesandexposuretoharmfulradiation.Toaddresstheseissues,researchershavebeendevelopingmaterialswithstrongelectromagneticwaveabsorptionproperties,whichcanbeusedforelectromagneticshieldingandstealthtechnology.

Onepromisingmaterialforelectromagneticwaveabsorptionisaerogels.Aerogelsarehighlyporousmaterialswithathree-dimensionalinterconnectednetworkofnanometer-sizedpores.Thisuniquestructuregivesaerogelsalargesurfaceareaandlowdensity,whichmakesthemhighlyefficientatabsorbingandscatteringelectromagneticwaves.

Recently,anewcompositeaerogelmadeofCo/CuFe2O4@NGwasdevelopedforelectromagneticwaveabsorption.Theaerogelwassynthesizedthroughasimplesolvothermalmethod,whichinvolvedmixingcobaltnitrate,coppernitrate,andironnitratewithgrapheneoxide(GO)andthenreducingthemixturewithhydrazine.TheresultingCo/CuFe2O4@NGcompositewasthenfreeze-driedtoproducetheaerogel.

TheCo/CuFe2O4@NGcompositeaerogelshowedstrongelectromagneticwaveabsorptionpropertiesinthefrequencyrangeof2–18GHz.Themaximumreflectionloss(RL)valueoftheaerogelwas-38.5dBatathicknessof4.5mm.ThishighRLvalueindicatesthattheaerogelishighlyeffectiveatabsorbingelectromagneticwaves.

ThesuperiorelectromagneticwaveabsorptionpropertiesoftheCo/CuFe2O4@NGcompositeaerogelareattributedtoitsuniquestructure.Theaerogelhasahighlyporousnetworkofinterconnectednanometer-sizedpores,whichcreatesalargecontactareaforelectromagneticwaveabsorption.Thepresenceofcobaltandcopperinthecompositefurtherenhancestheelectromagneticwaveabsorptionproperties.

TheCo/CuFe2O4@NGcompositeaerogelhaspotentialapplicationsinthefieldsofelectromagneticshieldingandstealthtechnology.Electromagneticshieldingreferstotheuseofmaterialstopreventelectromagneticwavesfrompenetratingthroughasurface,whilestealthtechnologyreferstotheuseofmaterialstoreducetheradarcrosssection(RCS)ofanobject,makingitlessdetectablebyradar.Thehighelectromagneticwaveabsorptionpropertiesoftheaerogelmakeitanidealcandidateforbothapplications.

FutureworkwillfocusonoptimizingthecompositionandstructureoftheCo/CuFe2O4@NGcompositeaerogeltofurtherenhanceitselectromagneticwaveabsorptionproperties.Thiscouldinvolve