Ideally polarizable interface

A typical example of an ideal polarizable interface is the mercury-solution interface [1,2]. From an experimental point of view it is characterized by its electrocapillary curve describing the variation of the interfacial tension 7 with the potential drop across the interface, 0. Using the thermodynamic relation due to Lippmann, we get the charge of the wall a (-a is the charge on the solution side) from the derivative of the electrocapillary curve ... 

The situation that no charge transfer across the interface occurs is named the ideal polarized or blocked interface. Such interfaces do not permit, due to thermodynamic or kinetic reasons, either electron or ion transfer. They possess Galvani potentials fixed by the electrolyte and charge. Of course, the ideal polarizable interface is practically a limiting case of the interfaces with charge transfer, because any interface is always permeable to ions to some extent. Therefore, only an approximation of the ideal polarizable interface can be realized experimentally (Section III.D). 

When we discussed the double-layer properties of metal electrodes in contact with an electrolyte solution, we introduced the notion of an ideally polarizable interface, which is marked by the absence of charge-... 

Ideal polarizable interfaces are critical for the interpretation of electrochemical kinetic data. Ideality has been approached for certain metal electrode-solution interfaces, such as mercury-water, allowing for the collection of data that can be subjected to rigorous theoretical analysis. 

Under these circumstances [12, 13], the ITIES behaves as an ideally polarizable interface, i.e. within a certain range of electrical potential values between water and the organic phase, attains the value applied from an external source. 

Mercaptohexadecanol, adsorption, 979 Mercury in electrode kinetics, 1093, 1195 Mercury solution interface, ideal polarizable interface, 848 Metal capacity, 888 determination. 890 -water interactions, 896, 897... 

Fig. 6.33. (a) The equivalent circuit for an electrified interface is a capacitor and resistor connected in parallel, (b) In the equivalent circuit for an ideally polarizable interface, the resistance tends to infinity, and fora nonpolarizable interface, the resistance tends to zero. 

Consider mercury as the liquid metal under study. One of the advantages of this metal is that the mercuiy/solution interface approaches closest to the ideal polarizable interface (see Section 6.3.3) over a range of 2 V. What this means is that this interface responds exactly to all the changes in the potential difference of an external source when it is coupled to a nonpolarizable interface, and there are no complications of charges leaking through the double layer (charge-transfer reactions). 

In Section 6.3.3 the polarizability of an interface was discussed. To revise what was said earlier, the ideal polarizable interface is one in which, when the potential on the metal side is forced to move in the positive or negative direction, there is a change of potential across the interpliasial region, but no consequent passage of charge across the interface. 

Impedance spectroscopy a single interface. Draw the equivalent circuits for the following electrode/electrolyte interfaces, then derive their impedance expression and explain what their Cole-Cole plot will look like (a) An ideally polarizable interface between electrode and electrolyte, (b) An ideally nonpolarizable interface between electrode and electrolyte, (c) A real-life electrode/... 

The liquid metal mercury-solution interface presents the advantage that it approaches closest to an ideal polarizable interface and, therefore, it adopts the potential difference applied between it and a non-polarizable interface. For this reason, the mercury-solution interface has been extensively selected to carry out measurements of the surface tension dependence on the applied potential. In the case of other metal-solution interfaces, the thermodynamic study is much more complex since the changes in the interfacial area are determined by the increase of the number of surface atoms (plastic deformation) or by the increase of the interatomic lattice spacing (elastic deformation) [2, 4]. 

The thermodynamic properties of an ideally polarizable interface are most easily examined by considering an electrochemical cell with one polarizable electrode and one non-polarizable electrode. An example of such a system is... 

Ideally Polarizable Interface with Supporting Electrolytes. 

Potentiometric Results. As shown earlier, a single salt concentration variation has no effect on the interfacial potential. Thus, to study the effect of the dye cation on the interfacial potential, other ions must be present. Supporting electrolytes, selected in such a way that an ideally polarizable interface is formed when the dye is absent, are conveniently used. 

The total capacitance in the walls of the pores is given by C, = c,L. This capacitance is attributed to double-layer effects, so it is usually a function of the potential. It can also be used to describe the space-charge polarization at the semiconductor-liquid junction if the spatial distribution of electrical charge as a function of potential is known. An ideally polarizable interface with charge transfer can be described by considering the charge transfer as a resistance, ret, which goes in parallel to the capacitance so that the impedance element yields an impedance such as ... 

The principal object of electrochemical interest is given by another type of electrified interface, contacts of an electronic (liquid or solid metal, semiconductor) and an ionic (liquid solution, SEs, membranes, etc) conductor. For numerous contacts of this kind, one can ensure such ionic composition of the latter that there is practically no dc current across the interface within a certain interval of the externally apphed potential. Within this potential interval the system is close to the model of an ideally polarizable interface, the change of the potential is accompanied by the relaxation current across the external circuit and the bulk media that vanishes after a certain period. For sufficiently small potential changes, d , the ratio of the integrated relaxation current, dQ, to dE is independent of the amplitude and it determines the principal electrochemical characteristics of the interface, its differential capacitance per unit surface area, C ... 

Fig. 1 An arbitrary scheme of the structure of a perfectly polarizable interface between two immiscible liquids (a, b, c, d) and an ideally polarizable interface (b, c).

At the ideally polarizable interface, the ions of each group are separated by the... 

---