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1、液/液界面电化学及电 分析化学简介,邵元华, 教授,College of Chemistry and Molecular Engineering Peking University,二00二年十一月,1.液/液界面电化学的发展历史 2.液/液界面电化学的基本原理 3.液/液界面电化学的主要研究方法 及仪器设备 4.液/液界面电化学的现状 5.液/液界面电化学的未来展望,主要内容,参考书和文献： 1. 液/液界面电化学， P.Vanysek 著， 罗颖华 译，汪尔康 审校， 吉林大学出版社， 1987年 2. H.H.Girault and D.J.Schiffrin, in Electroan
2、alytical Chemistry, A.J.Bard., Ed.; Vol:15, p.1, Marcel Dekker, New York ,1989 3. H.H.Girault, in Modern Aspects of Electrochemistry, J.O.Bockris, B.E.Conway, R.E.White, Eds.; Plenum Press, New York, 1993, Vol:25, p.1 4. J.Koryta, Electrochemical polarization phenomena at the interface of two immisc
3、ible electrolyte solutions. Electrochimica Acta, 24(1979)293-300 5. J.Koryta, Electrochemical polarization phenomena at the interface of two immiscible electrolyte solutions. II. Progress since 1978. Electrochimica Acta, 29(1984)445-452 6. Volkov A G, Deamer D W. Liquid-liquid interfaces. Theory and
4、 Methods. California: CRC Press, 1996.,1. Brief Introduction of Electrochemistry at Liquid/Liquid Interfaces,应用电化学方法研究电荷在液/液界面上的转移 反应 - 液/液界面电化学. 它是电化学及电分析化学的一个重要分支，也 是生物电化学的一个重要组成部分。,Charge (electron and ion) transfer across Liquid/ Liquid (L/L) interfaces, or Oil/Water interfaces, or the interface
5、 between two immiscible electrolyte Solutions (ITIES) is one of the most fundamental physicochemical processes.,Brief history: 1902, Nernst and Riesenfeld 1906, Cremer pointed out that the analogy between the water/oil/water concentration cells and biological membrane 1939, Verwey and Niessen, first
6、 theoretical paper on the electrical double layer and potential distribution at ITIES 1970s, Gavach et al. in France 首先认识到 L/L 界面在一定 的实验条件下可以被极化， 并用Chronopotentiometry 对 一些简单离子在Water/Nitrobenzene (W/NB)的转移行为进 行了研究。同时用Modified Verwey-Niessen (MVN)对实验 结果进行了分析。随后 Koryta et al. 发展了滴水电极及相 应的实验装置，并首先研究了中性
7、载体加速离子转移反 应。Samec et al. in 1979设计了具有iR降补偿性质的四电极 恒电位仪，用来记录离子转移反应的伏安图。这样L/L界 面电化学才在世界各地得到普及和蓬勃发展。,1980s, 汪尔康先生等是中国第一个从事L/L界面电化学 研究的group 1986, Girault et al. 第一个将微-L/L界面支持在 Micropipettes 上 1991, Corn et al. 应用SHG研究L/L界面 1995，Mirkin and Bard et al. 应用SECM 研究L/L界面 1997, Y.Shao et al. 第一个将纳米级-L/L界面支持在 N
8、anopipettes 上 最近几年各种光谱技术也应用于此领域的研究,Gold，Pt，C,NB 1,2-DCE,The difference between L/L interface and Electrode/Electrolyte interface,Electrochemistry of L/L interfaces,O + e = R,Redox Reactions,O + e = R,Redox Reactions,MZ (w) = MZ(o),Ion Transfer,the conventional Electrochemistry,The difference between
9、 Electrochemistry at L/L interface and the conventional Electrochemistry,Electrochemistry at L/L Interfaces is the bridge between the conventional electrochemistry and Chemical sensors,Electrochemistry at Liquid/Liquid Interfaces is a fast way to select receptors for making chemical sensors,Electrod
10、e,O,Biological Membrane Model,L/L Interface,Electrode/electrolyte,Membrane /solution,Artificial ,supported membrane and BLM,Electrochemistry at L/L Interfaces,New Branch of Electrochemistry,Mechanism of Chemical sensors,Phase Transfer catalytic reactions,Mimicking biological membranes,Research Signi
11、ficance and applications of Electrochemistry at L/L Interfaces,Extraction Mechanism,2.液/液界面电化学的基本原理,2.1.Equilibrium conditions and Nernst potential In general at Liquid/Liquid interfaces, there are two types of charge partition: (A) the transfer of an ion M with the charge number z from the phase w
12、to the phase o and the reverse: MZ(w) = MZ(o) M+(w) + L(o) = ML+(o) (B) the electron transfer between a redox couple O1/R1 in the phase w and a redox couple O2/R2 in the phase o, which can be represented as: O1(w) + R2(o) = R1(w) + O2(o),Nernst Equations,Liquid/Liquid interfaces have been classified
13、 into the ideal-polarized interface and no-polarized interface.,2.2.Single ion Gibbs energy of transfer TATB assumption,2.3.Solvation of Ion Born equation,2.4.Interfacial structure and the ion transfer mechanism (A)MVN MODEL (B)GS MODEL,2.5.Solvents and base electrolytes There are over 20 organic so
14、lvents which have been tested in the ITIES studies so far. As pointed out by Koryta et.al., the following three requirements have been commonly used to choose the organic solvent: (1). The solubility of solvent in water and water in the solvent must be very small. (2). The solvent must be sufficient
15、ly polar to promote sufficient dissociation of the supporting electrolyte and thus keeping enough conductivity of the solution. (3). The density of the solvent should differ significantly from that of aqueous phase in order to get a physically stable l/l interface.,At present, the most commonly used
16、 organic solvents are nitrobenzene(NB) and 1,2-dichloroethane (1,2-DCE). Some other solvents have been tried in the past two decades, for example, propiophenone, 4-isopropyl-1-methyl-2-nitrobenzene, dichloro- methane,nitrotulene, chloroform, aniline etc. In order to get more flexible choice, organic solvent mixtures have been also employed, for example, nitrobenzene + chlorobenzene, NB + benzonitrile and NB + benzene. Base electrolytes: TBATPB (tetrabutylammon
