Chapter 5 Hydrodynamic Electrodes

Abstract

Publisher Summary This chapter describes the application of hydrodynamic electrodes to the study of electrode kinetics and the kinetics of electrode and coupled homogeneous reactions. Combination of hydrodynamic electrodes and non-steady-state techniques, though more complex to analyze theoretically, is very powerful in its application with increased sensitivity. To be able to describe quantitatively the flux of electrons at an electrode, the flux of material reaching the electrode, which can result from convection, diffusion, and migration processes, should be known. Double electrodes are, particularly useful in kinetic studies. Intermediates produced on the generator (upstream) electrode are transported to the downstream electrode where they react further. This is useful for the study of short-lived species, the quantity reaching the second electrode depending on any homogeneous reactions or decomposition occurring in solution. Certain criteria have to be met in the construction of hydrodynamic electrodes, such that the laminar flow pattern, which is used in the derivation of the theoretical equations, is conformed to. Three-electrode control systems are widely available in the market, and there are also four-electrode systems for double working electrodes. Electrochemically generated radicals may be photochemically active, measurable by Electron-Spin Resonance (ESR) techniques, or both. Conversely, species generated photochemically in solution may be electrochemically active. By using hydrodynamic electrodes with known flow patterns, the kinetics of these systems can be studied more easily.