北京大学电分析课件电分析化学原理、方法和应用.ppt

2.2 电池的电动势和电极电势 界面电势(绝对电势及绝对电势差) 内电势(Galvani, ?), 外电势(Volta, ?)和表面电势(?) 外电势(Volta, ?): 将单位正电荷从无穷远处的真空中移到物体 近旁距表面约10-4cm处作的功。(是可测的) 金属和电解质溶液界面外电势之差，叫做Volta电势： ?? =?电极 - ?溶液 表面电势(?)：将单位正电荷从物体表面附近的一点移到物体 相内所做的电功称之为表面电势(涉及到化学作用，是不可测 的)。 ? = ? + ? “电位” 与 “电势”的区别！ ?? = ?? +?? = ze? = ze? =ze? +ze? +? =ze? + ? (电化学势) Figure. A schematic diagram to illustrate that, in the interphase region (indicated by shading), there generally is net dipole orientation and net, or excess, charge density An electrode is like a giant central ion Electrode/electrolyte Double layer Double layers are characteristic of all phase boundaries 1V, 1nm, the field strength (gradient of potential) is enormous - it is of the order 107 V/cm. The effect of this enormous field at the electrode- electrolyte interface is, in a sense, the essence of electrochemistry! A ? (a)物质相的内电势、外电势和表面电势 (b)电极与溶液间的内电位差和外电位差 To measure the potential difference across a metal- solution electrified interface (see exploded view), one terminal of the potential- measuring instrument is connected to the metal electrode. What is to be done with the second terminal? All one can measure, in practice, is the potential difference across a system of interfaces, or cell, not the potential difference across one electrode-electrolyte interface. * Fundamentals of Electroanalytical Chemistry 电分析化学原理、方法和应用 Yuanhua Shao（邵元华，教授 Ph.D.） College of Chemistry and Molecular Engineering Peking University Outline: 1. Principles 2. Methods 3. Applications Part 1 Principles 1. Introduction 2. Electrochemical Cell: Thermodynamic Properties and Electrode Potentials 3. The Interfacial Region 4. Fundamentals of Kinetics and Mechanism of Electrode Reactions 5. Mass Transport 6. Kinetics and Transport in Electrode Reactions Part 2 Methods 1 Electrochemical Experiments 2 Hydrodynamic Electrodes 主要内容 Part 2 Methods 3 Cyclic Voltammetry and Linear Sweep Techniques 4