17.3 - Electrochemistry at liquid/liquid interfaces

Abstract

Charge (electron and ion) transfer at a liquid/liquid (L/L) interface, or at an oil/water (O/W) interface, or at an interface between two immiscible electrolyte solutions (ITIES) is one of the most fundamental physicochemical processes. When two electrically conducting phases such as w (water) and o (organic) are in contact, the partition of the charge carriers (electron and ion) between the two adjoining phases occurs due to the difference in energy of the carriers in both phases. Thus, an interfacial region is built up. The distribution of the potential at the interfacial region is related to the structure of the interface. One of the characteristics of electrochemistry at liquid/liquid interfaces is the diversity of charge transfer reactions which can be studied by electrochemical methodologies. These charge transfer reactions can be classified into three main categories: (a) ion transfer (IT) reaction; (b) facilitated ion transfer (FIT) reaction; (c) electron transfer (ET) reaction. Various methodologies and techniques such as the four-electrode system, two-electrode system, and three-electrode system may be used for electrochemical measurements at a liquid/liquid interface. Charge transfer reactions at liquid/ liquid interfaces find their application in pharmacokinetics, amperometric sensors, and electrochemical imaging. An important aspect of charge transfer reactions at a L/L interface is that all three types of transfer reactions can be employed to obtain imaging of various kinds of substrates and information about reactivity.