Subject rotating disc electrodes

In many respects, similar to the diffusion layer concept, there is that of the hydrodynamic boundary layer, <5H. The concept was due originally to Prandtl [16] and is defined as the region within which all velocity gradients occur. In practice, there has to be a compromise since all flow functions tend to asymptotic limits at infinite distance this is, to some extent, subjective. Thus for the rotating disc electrode, Levich [3] defines 5H as the distance where the radial and tangential velocity components are within 5% of their bulk values, whereas Riddiford [7] takes a figure of 10% (see below). It has been shown that... 

The purpose of the present book is to satisfy this need. The book starts by covering the basic subjects of interfacial electrochemistry. This is followed by a description of some of the most important techniques (such as cyclic voltammetry, the rotating disc electrode, electrochemical impedance spectroscopy, and the electrochemical quartz-crystal microbalance). Finally, there is a rather detailed discussion of electroplating (including alloy deposition), corrosion, and electrochemical energy conversion devices (batteries, fuel cells and super-capacitors). 

In the model developed, the rates of mass-transfer processes are described in terms of the rotation frequency of a RDE. Under the conditions in which the experiments were performed the electrolyte flow at the surface of the magnetite disc electrode is laminar. Consequently, the quantitative treatment of the mass-transfer process would have to be modified in order use the model to predict the rate of magnetite dissoiution from pipe wails subject to turbulent flow. 

In a typical experiment with semiconductor-liquid junctions, one of the most important experimental problems is the differentiation between reactions that involve chemical changes at the semiconductor electrode (corrosion with insoluble products) and chemical changes in the electrolyte that might be subject to mass transfer limitations. The technique of Rotating Ring Disc Electrode (RRDE) (17-19) provides an opportunity to differentiate between these two types of reactions under controlled hydrodynamic conditions. In its simplestform, the metallic ring is isolated... 

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