Construction and properties of a continuously renewing platinum electrode

A continuously renewing platinum electrode is created by positioning two electrochemical cells symmetrically around a platinum ball so that opposite sides of the ball are pressed against gaskets situated in holes in the walls of the two cells. Thereby two opposite segments of the surface of the platinum ball are in contact with the electrolytes in the two cells and can be polarised independently with respect to the two electrolytes. When the ball is rotated the surface segment, which constitutes one electrode, is continuously being replaced by surface arriving from the segment, which constitutes the other electrode. By proper choice of electrolytes and potentials material deposited on the electrode surface in one cell may be released in the other cell. The effect is demonstrated with hydroxyl, sulfate and cupric ions. The transport of hydroxyl ions from one cell to the other is subject to anodic passivation caused by the formation of a surface layer of Pt-oxide. Continuous renewal of the catalytic activity of the platinum electrode due to continuous removal of inhibitory material is demonstrated with the electrooxidation of methanol. The oxidation of methanol is subject to anodic passivation caused by bound sulfate ions.