After polishing, the electrode was repeatedly washed with high purity water and subjected to sonication for 10 to 20 s. To provide effective removal of any residual alumina powder, after the initial sonication, the electrode was carefully wiped with a clean wet polishing cloth, again washed with water and sonicated for 10 to 20 s in high purity water. Finally, the working electrode was dried under a nitrogen stream. As far as possible, each electrode preparation was undertaken under identical conditions; nevertheless, the electrode kinetics differ substantially from experiment to experiment. However, of course the history of the electrode could be important since the electrode used for experiment ten will have a more extensively polished electrode than that used in experiment one.