Electrochemistry. Current-potential characteristics: theory (part 1)

As pointed out in the general introduction , the design and development of any electrochemical process must begin with an analytical study to characterize the processes involved, using an experimental methodology known as voltammetry, which consists in determining the variation of the electrolysis current at one electrode (independently of what is happening at the other electrode) as a function of its potential (voltammogram, expressing the electrode current-potential relationship).

The characterization obtained is global, i.e. it integrates the contributions of all the physico-chemical processes that take place at the electrode in question and in the electrolyte in contact with it, under the conditions that must be those of the electrolysis envisaged. Interpretation of the experimental voltammetric characteristic therefore provides an insight into these processes. But, conversely, this global characterization is suitable for selecting the conditions for carrying out an electrochemical operation, such as those which give rise to industrial processes.

The current-electrode potential relationship can be the subject of a predictive study based on the theoretical characteristics of electrochemical processes, which have been set out in the article "Electrochemistry. Laws governing processes". The purpose of this article is now to describe (briefly) the predictable morphology of electrode current-potential characteristics, considering in particular their dependence on various physical and especially chemical factors (chemical influence of the electrolytic medium on electroactive constituents in solution, depending on their acid-base properties or their ability to form complexes and/or insoluble compounds).

Observable current-potential characteristics for electrochemical systems involving metals are discussed in the paper [J 1 607], which is a direct sequel to this article.

The principles and methodology of voltammetry –– are described in articles [P 2 125] et seq. in the "Electrochemical methods" section of the "Analysis and characterization" treatise. The reader is referred to the specific article on voltammetry in this section for the experimental procedure for this study method, which will not be described again here.