Hydrodynamic voltammetry rotating disc electrode

The last of these is the impedance which has been considered throughout this chapter. We now consider forced convection. For low frequencies the diffusion layer thickness due to the a.c. perturbation is similar to that of the d.c. diffusion layer in these cases convection effects will be apparent in the impedance expressions. For the rotating disc electrode these frequencies are lower than 40 Hz33. For higher frequencies where the two diffusion layers are of quite different thicknesses, the advantage of hydrodynamic electrodes is that transport is well defined with time, as occurs with linear sweep voltammetry. 

Examples of electrode reaction mechanisms consisting of extensive combinations of E and C steps 42 Hydrodynamic voltammetry 44 Rotating-disc electrodes 46 Channel electrodes 48 Wall jet electrodes 52 Electron-transfer processes 53... 

As discussed in Section 2 material may reach the electrode surface by diffusion or convection. In cyclic voltammetry at a stationary electrode, and assuming that migration can be neglected, diffusion is the sole form of mass transport. However, material may additionally be transported to the electrode by convection. This genre of voltammetry, where convection is a dominant form of mass transport, is described as hydrodynamic voltammetry. The focus in Section 4 will be on the use of rotating disc and channel electrodes in studies... 

This book is aimed at students, researchers and professors in the broad area of electrochemistry who wish to simulate electrochemical processes in general, and voltammetry in particular. It has been written as a result of numerous requests over recent years for assistance in getting started on such activity and aims to lead the novice reader who has some prior experience of experimental electrochemistry at least, from a state of zero knowledge to being realistically able to embark on using simulation to explore nonstandard experiments using cyclic voltammetry, microdisc electrodes and hydrodynamic electrodes such as rotating discs. 

An armoury of powerful electrochemical methods is available. Potential step techniques such as differential pulse DP or square-wave SW voltammetry offer advantages in sensitivity and resolution. Hydrodynamic techniques involving use of rotating disc or rotating ring-disc electrodes allow the chemical steps of the electrode process to be separated from mass transport. Electrochemical transformations may be monitored optically with spectroelectrochemical methods. Even the electrode interface itself is amenable to study by in situ spectroscopic techniques. Detailed descriptions of these methods are to be found in appropriate texts [1-4]. 

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