Ring electrodes materials

Species generated at the disc electrode are transported by the flow already described above. Provided a suitably set ring electrode material and potential are applied, they can be detected there. In case of the electroreduction of Cu -ions, the stepwise reduction via Cu depending on the disc electrode potential becomes easily visible (Fig. 6). 

Figure 1. Rotating ring-disk electrode. 1 disk electrode material, 2 ring electrode material, 3 insulator, 4 metal support, r, disk radius, T2 inner ring radius, outer ring radius, r overall radius of the tip.

It is often convenient to make a number of studies with the same ring electrode but different disc materials for comparison purposes. Such ring-disc electrodes with demountable discs have been described based on press-fitting [105, 117, 118], cone-fitting [119, 120], and screw-thread [121] principles. 

As general trend, it can be observed that for most of the studied phenolic compounds the anodic oxidation at BDD was very fast and, if the applied current density was sufficiently high, the kinetics of the process was under mass-transfer control and it was not appreciably dependent on the nature of the substituting groups in the aromatic ring, as it was reported at more usual electrode materials, like platinum (Torres et al. 2003). 

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