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1、物理化學(xué)學(xué)報(WuliHuaxueXuebao)MayActaPhys.一Chim.Sin.,2010,26(5):1239—12481239[Article】www.whxb.pku.edu.cn電極/離子液體界面電容趙娣黃青金先波,魏獻軍陳政L'(武漢大學(xué)化學(xué)與分子科學(xué)學(xué)院,武漢430072;ZDepartmentofChemicalandEnvironmentalEngineeringFacultyofEngineering,TheUniversityofNottingham,NottinghamNG72RD,UK)摘要:用電化學(xué)阻抗方法研究了鉑片
2、電極在BMIMPF6,BMIMBF4,BMIMC10,BMIMTf2N,BMIMC1,BMIMBr,C3OHMIMBG.C3OHMIMC104和BMMIMPF6MIM:1-buty1-3-methylimidazolium;C3OHMIM:1-0一hydroxypropy1)-3-methylimidazolium;BMMIM:1-butyl-2..methyl--3--methylimidazolium;Tf2N:bis(trifluoromethylsulfony1)amide)離子液體中的界面電容及結(jié)構(gòu).結(jié)果表明:當(dāng)陰、陽離子半徑相差不大且不存在特
3、性吸附時,在零電荷電勢附近,電極腐子液體界面的電容一電勢曲線將出現(xiàn)電容單峰或者雙峰.電極的零電荷電勢對應(yīng)于單峰的峰電勢或者雙峰之間的谷電勢.當(dāng)電極電勢遠離零電荷電勢時,電極/離子液體界面成緊密層結(jié)構(gòu),可由緊密層理論來描述.如果存在離子的特性吸附,相應(yīng)的電容峰可能不再出現(xiàn),而表現(xiàn)為雙層電容隨電極電勢對零電荷電勢的偏離而單調(diào)增加.還研究了添加小的Li+離子對電極廠離子液體界面電容的影響.通過向BM1MTf2N中加入LiTf2N,發(fā)現(xiàn)Li璃子可以改變電極腐子液體界面的雙層結(jié)構(gòu),但無助于界面電容的提高,甚至可能引起電容的降低.最后探討了不同條件下,尤其考慮陰陽離
4、子特性吸附時,電極,離子液體的界面結(jié)構(gòu).關(guān)鍵詞:電化學(xué)電容;離子液體;電極/電解液界面;界面離子排列;電化學(xué)阻抗譜中圖分類號:0646CapacitanceattheElectrode/IonicLiquidInterfaceZHAODiHUANGQingJINXian—Bo,WEIXian—JunCHENGeorgeZ.衛(wèi)(CollegeofChemistryandMolecularScience,WuhanUniversity,Wuhan430072,P.R.China;2DepartmentofChemicalandEnvironmentalEng
5、ineering.FacultyofEngineering,TheUniversityofNottingham,NottinghamNG72RD,UK)Abstract:TheinterfacialstructureandcapacitanceofaPtfoilelectrodewereinvestigatedbyelectrochemicalimpedancespectroscopyinvariousionicliquidsincludingBMIMPFe,BMIMBF“BMIMC10~BMIMTf2N,BMIMC1,BMIMBr,C3OHMIMBF4
6、,C30HMIiV~C104andBMMIMP(BMIM:1-butyl一3一methylimidazolium,C30HMIM:1一(3一hydroxypropy1)一3一methylimidazolium,BMMIM:1-bu哆l一2一methyl一3一methylimidazolium,Tf2N:bis(trifluoromethylsu—fony1)amide).Theresultsindicatethatwhentheanionandcationoftheionicliquidareofcomparablesizeanddonotadsorbs
7、pecificallyontheelectrode,the“capacitance—potential’’curvenearthepotentialofzerochargeexhibitseitheronepeakortwopeaks.Thepotentialofzerochargecorrespondstoeitherthepeakpotentialorthevalleypotentialonthecapacitance-potentialcurvewithonepeakortwopeaks,respectively.Whenthepotentiali
8、spositiveornegativetothepotentialofzeroc