Electrochemical techniques, classification

FIGURE 4-27 Classification of composite electrodes used in controlled-potential electrochemical techniques. (Reproduced with permission from reference 87.)... 

In order to give an overview of the many electrochemical techniques, it is convenient to classify them. Table 5.1 is an example of such a classification. All electro-... 

The classification of chemical structure using electrochemical techniques, is a challenging problem. Voltammetric responses lack fine structure and probably will never compete with spectroscopic methods in qualitative analysis. The complex dependence of an electrochemical response on many variables, and theoretical... 

At first sight, electrochemical textbooks [21, 22] contain a dazzling number of techniques, each of them described by the appropriate mathematics, and it can be difficult to recognize the special features that makes a technique suitable for some particular purpose. Therefore, a certain classification will be useful. 

Refs. [i] Kolthoff IM, Lingane JJ (1952) 2nd edn. Polarography. Polarographic analysis and voltammetry. Amperometic titrations. Interscience, New York, vol. 2, pp 887 [ii] Heyrovsky J, Kuta J (1966) Principles of polarography. Academic Press, New York, pp 267 [Hi] Classification and nomenclature of electroanalytical techniques (1976) Pure Appl Chem 45 81 [iv] Bard AJ, Faulkner LR (2001) Electrochemical methods, 2nd edn. Wiley, New York, pp 437... 

A large number of electrochemical methods exist which are or have the potential to be useful in the study of reactive intermediates. The methods are conveniently categorized according to the quantity measured, usually the current, potential, or some optical property of the reactants or the intermediates. A further classification arises from the manner in which experiments are conducted, i.e. transient or steady state measurements. In this brief survey only those techniques which have been reduced to useful practice are discussed and even then the coverage is not exhaustive. More detailed discussion can be found in several excellent references sources (Bard, 1966-present MacDonald, 1977 Bard and Faulkner, 1980). 

Most electrochemical studies carried out today make use of online computers for control of experiments and for data acquisition and analysis, including the techniques described earlier. Examples of the application of computer evaluation of experimental results include, for instance, pattern recognition [151] and the recording of current-time profiles of the form A(lni)/A(lnt) versus t for mechanistic classification [152] as well as nonlinear regression techniques [153-155]. Efforts have also been made to use knowledge-based systems for the elucidation of reaction mechanisms [156]. 

Chemistry (lUPAC) titled "Classification and Nomenclature of Elec-troanal)d icar Techniques" [1], "Recommended Terms, Symbols, and Definitions for Electroanal Aical Chemistry" [2], and "Recommended Terms, Symbols, and Definitions for Electroanal d ical Chemistry (Recommendations 1985)" [3] and in Compendium of Analytical Nomenclature The Orange Book [4]. Some special articles characterize electrochemical sensors [5]. A special lUPAC technical report, "Electrochemical Biosensors Recommended Definitions and Classification" [6], deals with techniques and terms of electrochemical biosensors. 

Three broad classifications of electrochemical methods are used in this chapter. Po-tentiometric methods include zero-current potentiometry and methods in which current of controlled magnitude is apphed to the working electrode, such as in potentiometric stripping analysis (PSA). Amperometric methods consider all techniques in which current is measured these include constant-potential amper-ometry and amperometric measurements made in response to a variety of applied potential waveforms in voltammetric methods. Impedimetric methods comprise a final classification in these methods, faradaic currents are generally absent, and impedance, conductance, or capacitance is the measured property. 

K. Toth, K. Stulik, W. Kutner, Z. Feher, E. Linder, Electrochemical detection in liquid flow analytical techniques characterization and classification (lUPAC technical report). Pure Appl. Chem. 76 (2004) 119-1138. 

We present an introduction to sol-gel processing with an emphasis on sih-cate formation. Dip- and spin-coatings, the two most nsefnl thin-tilm processing techniques for electrochemical applications, are briefly described. The section on thin films also includes an expanded account of recent developments in sol-gel electrodeposition of functional silicates, a field that has recently attracted considerable scientific attention. A classification of ways to electrodeposit thin films is provided. 

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