Applications
The RRDE setup allows for many additional experiments well beyond the capacity of a RDE. For example while one electrode conducts linear sweep voltammetry the other can be kept at a constant potential or also swept in a controlled manner. Step experiments with each electrode acting independently can be conducted. These as well as many other extremely elegant experiments are possible, including those tailored to the needs of a given system. Such experiments are useful in studying multi-electrons processes, the kinetics of a slow electron transfer, adsorption/desorption steps, and electrochemical reaction mechanisms.
The RRDE is an important tool for characterizing the fundamental properties of electrocatalysts used in fuel cells. For example, in a proton exchange membrane (PEM) fuel cell, dioxygen reduction at the cathode is often enhanced by an electrocatalyst comprising platinum nanoparticles. When oxygen is reduced using an electrocatalyst, an unwanted and harmful by-product, hydrogen peroxide, may be produced. Hydrogen peroxide can damage the internal components of a PEM fuel cell, so oxygen-reduction electrocatalysts are engineered in such a way as to limit the amount of peroxide formed. An RRDE "collection experiment" can be used to probe the peroxide generating tendencies of an electrocatalyst. In this experiment, the disk is coated with a thin layer bearing the electrocatalyst, and the disk electrode is poised at a potential which reduces the oxygen. Any products generated at the disk electrode are then swept past the ring electrode. The potential of the ring electrode is poised to detect any hydrogen peroxide that may have been generated at the disk.
Read more about this topic: Rotating Ring-disk Electrode