Electrochemical and Bioelectrochemistry

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Anal.Chem.2004,76,4960-4967

ElectrochemicalandBioelectrochemistry

PropertiesofRoom-TemperatureIonicLiquidsandCarbonCompositeMaterials

FengZhao, XueeWu, MingkuiWang, YingLiu, LianxunGao, andShaojunDong*,

StateKeyLaboratoryofElectroanalyticalChemistry,andStateKeyLaboratoryofPolymerPhysicsandChemistry,ChangchunInstituteofAppliedChemistry,ChineseAcademyofSciences,Changchun130022,China

Room-temperatureionicliquids(RTILs)areliquidsatroomtemperatureandrepresentanewclassofnonaque-ousbutpolarsolventswithhighionicconductivity.Theconductivitypropertyofcarbonnanotubes/RTILsandcarbonmicrobeads/RTILscompositematerialshasbeenstudiedusingacimpedancetechnology.EnzymecoatedbyRTILs-modifiedgoldandglassycarbonelectrodesallowefficientelectrontransferbetweentheelectrodeandtheproteinandalsocatalyzethereductionofO2andH2O2.

Room-temperatureionicliquids(RTILs)areionicmediaresultingfromthecombinationoforganiccationsandvariousanions;theyareliquidsatroomtemperatureandrepresentanewclassofnonaqueousbutpolarsolventswhichareabletodissolvemanycompounds.Theyhaveionicconductivity,nonvolatility,andflameresistanceandpossessnovaporpressure.1-3RTILsaresuchaninterestingseriesofmaterialsthattheinvestigationofRTILshasgainedincreasingattentionwithsometimesremarkableresults.ThephasetransitionandrheologicalpropertiesofgelsformedafterbeinggroundwithRTILsandcarbonnanotubeshavebeenreportedrecentlybyAidaetal.4Thegelsdonotshrivelandshowthermalstabilityandtheapplicationforthefabricationofahighlyelectroconductivepolymer/nanotubecompositematerial.AnothermostexcitingrecentdevelopmentistheapplicationofbiocatalysisinRTILs.AnenzymecoatedbyRTILsshowinghigherselectivity,fasterrate,andgreatenzymestability5isdescribedasausefulcatalystforbiocatalysis.ThefurtherversatilityofRTILs

*Correspondingauthor.E-mail:dongsj@http://www.77cn.com.cn.Fax:+86-431-5689711.

StateKeyLaboratoryofElectroanalyticalChemistry.

StateKeyLaboratoryofPolymerPhysicsandChemistry.

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4960AnalyticalChemistry,Vol.76,No.17,September1,2004

wasdemonstratedbySummersetal.6whofoundimprovedproteinrefoldinginsimpleRTILs.

Mostofcarbon-basedmaterialsareelectricallyconductive;RTILsshowthepropertyofhighionicconductivity,buttherehasbeennoextensiveinvestigationintothemixedionicandelectricalpropertiesofhybridRTILs-carboncompositematerialsthatarealsoveryinteresting.

Immobilizationsofenzymesonelectrodesurfacesusingsol-gel,7polyelectrolyteorpolyions,8nanoparticles,9orcarbonnano-tube10,11conductingpolymers12orelectroactivepolymers10havebeendeveloped.TherehasbeennoreportaboutthedirectelectrochemistryofaproteinwithaRTILs-modifiedelectrodethoughRTILsshowspecialpropertiesforbiochemistry.

Inthepresentwork,weproposeanovelstrategyforinvestigat-ingtheelectrical-ionicpropertiesofRTILsandcarboncompositematerialsformedbymixingRTILsandcarbonmaterialsoftwotypes:oneismultiwallcarbonnanotubes(MWNTs)withatubeshapeandtheotherismesocarbonmicrobeads(MCMB)withabeadshape.ThehybridMWNTs/RTILsandMCMB/RTILsmaterialsshowadifferentconductivitymechanismdeterminedbyacimpedancetechnology.TheRTILsandcarboncompositematerialscanalsobeusedtoactasmodifiersinthedirectelectrochemistryofproteinandcatalyzethereductionofO2andH2O2.

EXPERIMENTALSECTION

InstrumentsandChemicals.Multiwallcarbonnanotubes(MWNTs,purity>95%,40-60nmdiameter,ShenzhenNanotech.PortCo.Ltd.China)andmesocarbonmicrobeads(MCMB,15-20µmdiameter,ShanshanCo.,China)werepurchased.Asrepresentativeenzymes,microperoxidase(MP-11,Sigma,Sydney,

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10.1021/ac0494026CCC:$27.50

©2004AmericanChemicalSociety

PublishedonWeb08/06/2004

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Figure1.Nyquistplot(a)andBodeplot(b)of[bmim]PF6atambienttemperature;thehigh-frequencyresponsehasbeenscale-expandedintheinset.Thefrequencyrangeisfrom105to0.01Hz,andtheperturbationsignalis5mV.

Australia)andperoxidasefromhorseradish(HRP,ShanghaiChem.Co.,China,250U)werepurchased.

TheacimpedancemeasurementswerecarriedoutwithanAutolab/PG30electrochemicalanalyzersystem(http://www.77cn.com.cnherlands)inagroundedFaradaycageatambienttemper-ature.Thesamplesweresandwichedbytwoparallelblockingplatinumelectrodesintoasealedglasscell.13Thear …… 此处隐藏：16193字，全部文档内容请下载后查看。喜欢就下载吧 ……