CYCLIC VOLTAMMETRY INVOLVING AMALGAM FORMATION AT MERCURY FILM MICROELECTRODES

Cyclic voltammetry involving amalgam formation at mercury microelectrodes is described experimentally and theoretically for reversible systems. Silver microdisks were used to support the mercury deposit during the preparation of electrodes. The ratio of the mercury film thickness to the disk radius is much lower than 1 (e.g., a 1 μm thick layer of Hg on a silver disk with a radius of 15 μm) justifies the name mercury film microelectrode. When the substrate is present in the solution, the original shape of the cyclic voltammograms (one or more cathodic waves followed by one or more anodic symmetrical peaks) is the result of the combination of spherical diffusion in the solution and restricted diffusion in the mercury film. When the substrate is present initially in the mercury phase, an anodic symmetrical peak is followed by a negligibly small cathodic peak. The alternate dimension implicit and the alternate direction Galerkin methods were used in the calculations. Copyright © 1990 VCH Publishers, Inc.