Co-assembly of ferrocene-terminated and alkylthiophene thiols.pdf

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1、JournalofElectroanalyticalChemistryJournalofElectroanalyticalChemistry563(2004)291–298www.elsevier.com/locate/jelechemCo-assemblyofferrocene-terminatedandalkylthiophenethiolsongoldanditsredoxchemistrymodulatedbysurfactantadsorptionZhangquanPeng,XiaohuQ

2、u,ShaojunDong*StateKeyLaboratoryofElectroanalyticalChemistry,ChangchunInstituteofAppliedChemistry,ChineseAcademyofSciences,Changchun,Jilin130022,PRChinaReceived17May2003;receivedinrevisedform4September2003;accepted16September2003AbstractCoadsorptionoff

3、errocene-terminatedalkanethiols(FcCO(CH)SH,Fc¼(g5-CH)Fe(g5-CH))withalkylthiophenethiols2285554(2-mercapto-3-n-octylthiophene)yieldsstable,electroactiveself-assembledmonolayersongold.Theresultingmixedmonolayerprovidesanenergeticallyfavorablehydrophobics

4、urfacefortheadsorptionofthesurfactantaggregatesinaqueoussolution.Theadsorptionshavebeencharacterizedviatheireffectontheredoxpropertiesofferrocenylalkanethiolsimmobilizedasminoritycomponentsinthemonolayersandontheinterfacialcapacitanceoftheelectrode.Surf

5、actantadsorptioncausesadecreaseintheoverallcapacitanceattheelectrodeanddramaticallyshiftstheredoxpotentialforferroceneoxidationinapositiveornegativedirectiondependingontheidentityofthesurfactantemployed.Astructuralmodelisproposedinwhichthealkanechainso

6、ftheadsorbedsurfactantsinterdigitatewiththoseoftheunderlyingself-assembledmonolayer,leadingtotheformationofahybridbilayermembrane.Ó2003ElsevierB.V.Allrightsreserved.Keywords:Monolayer;Bilayer;Goldelectrode;Cyclicvoltammetry;Doublelayer;Formalpotential1

7、.Introductiondominatethefaradaicresponseoftheblockingmono-layerinthepresenceofelectroactivespeciesfreelydif-Spontaneousadsorptionofsulfur-containingmole-fusinginelectrolytesolution.Butinanelectroactiveculesfromsolutionorthevaporphaseontooxide-freemonol

8、ayerthefaradaiccurrentduetoredoxcentersatmetals(especiallygold)toformclose-packedandori-ornearpinholesanddefectsbecomesanegligiblecom-entedmonolayersprovidesaconvenientmethodtoas-ponentofthetotalfaradaiccurrent,whichprovidessigndesiredc