应用循环伏安和交流阻抗技术研究了 16烷基硫醇自组装膜修饰的金电极在Fe(CN) 63 - /Fe(CN) 64 - 溶液中的电化学行为 .无“针孔”缺陷的自组装膜对溶液与基底间的界面电子转移具有强烈的阻碍作用 ,当过电位较大时 ,In(I/ η)对 η1/2 之间具有良好的线性关系 .通过对Au/SAM /Hg模拟体系的电流———电压曲线进行测定 ,得到了自组装膜膜电阻的特征 .指出由于膜电阻的存在 ,自组装膜修饰电极在Fe(CN) 63 - /Fe(CN) 64 - 溶液中的行为实质上反映了膜自身的电阻特征
The electrochemical behavior of gold electrode modified by hexadecanethiol self_assembled monolayer (SAM) in the solution of Fe(CN) 6 3- /Fe(CN) 6 4- was investigated by cyclic voltammetry and ac impedance spectroscopy. The pinhole_free SAM_modified gold electrode has excellent blocking properties to the interfacial electron transfer from redox couple in solution to the substrate. The current increased exponentially with the overpotential at the high potential region. A good linear relationship between ln( I/η ) and η 1/2 was observed. A model system Au/SAM/Hg was constructed and its I～V curve was measured. Similar phenomena were observed. There was also a linear relationship between ln( I/V ) and V 1/2 at high voltage region. It is proposed that the characteristic of pinhole_free SAM_modified gold electrode in solution of Fe(CN) 6 3- /Fe(CN) 6 4- mainly belongs to the resistance of the self_assembled monolayer itself.
[1] UlmanA .Formationandstructureofself_Assembledmonolayers[J].Chem.Rev.,1996,96:1533～1554.
[2] JanekRP ,FawcettWR ,UlmanA .Impedancespectroscopyofself_assembledmonolayersonAu(111):sodiumferrocyanidechargetransferatmodifiedelectrodes[J].Langmuir,1998,14:3011～3018.
[3] ZhaoJian_wei,DongShao_jun,LiuZhong_fan.Simulationofcharacteristicelectrochemicalbehaviorofa zobenzenederivativeself_assembledmonolayers(InChinese)[J].ChineseJournalofAnalyticalChemistry,2000,28(6):661～665.
[4] PorterMD ,BrightTB ,AllaraDL ,ChidseyCED .Spontaneouslyorganizedmolecularassemblies.4.Structuralcharacterizationofn_alkylthiolmonolanyersongoldbyopticalellipsometry,infraredspectroscopy,andelectrochemistry[J].J.Am.Chem.Soc.,1987,109:3559～3568.
[5] NahirTM ,BowdenEF .Impedancespectroscopyofelectroinactivethiolatefilmsadsorbedongold[J].Elec trochim.Acta.,1994,39:2347～2352.
[6] TetsuyaOsaka,ZhiyuJiang,ToshiyukiMomma,HimekoKanagawa.Stabilityofconductanceinelectroinac tivepolypyrrole[J].ThinSolidFilm,1994,237:268～271.
[7] SabataniE ,Cohen_BoulakiaJ ,BrueningM ,RubinsteinI .Thioaromaticmonolayersongold:anewfamilyofself_assembledmonolayers[J].Langmuir,1993,9:2974～2981.
[8] RampiMA ,SchuellerOJA ,WhitesidesGM .Alkanethiolself_assembledmonolayersasthedielectricofca pacitorswithnanoscalethickness[J].Appl.Phys.Lett.,1998,72:1781～1783.
[9] HaagR ,RampiMA ,HolmlinRE ,WhitesidesGM .Electricalbreakdownofaliphaticandaromaticself_as sembledmonolayersusedasnanometer_thickorganicdielectrics[J].J .Am.Chem.Soc.,1999,121:7895～7906.
[10] XieHong,YanManming,JiangZhiyu.TransitionofpolypyrrolefromelectroactivetoelectroinactivestateinvestigatedbyuseofinsituFTIRspectroscopy[J].Electrochim.Acta.,1997,42(15):2361～2367.
[11] ColemanRV ,BellLD ,DragosetRA ,JohnsonAM ,LuHao_An,PhillipsES .Barrierheightsandelec tric_field_inducedbarriershiftsindopedtunneljunctions[J].Phys.Rev.B ,1984,29:4246～4259.
[12] BaiChun_li.Thetheoryandapplicationsofscanningtunnelingmicroscopy(InChinese)[M ].Shanghai:ScienceandtechnologypressofShanghai.,1992.10:18～19.
[13] KrzysztofSlowinski,HaroldKYFong,MarcinMajda.Mercury_mercurytunnelingjunctions.1.Electrontunnelingacrosssymmetricandasymmetricalkanethiolatebilayers[J].J .Am.Chem.Soc.,1999,121:7257～7261
