Double layer effects in the electroreduction of transition metal ions

Experimental data for the reduction of transition metal complex ions obtained recently at mercury and single-crystal gold electrodes are reviewed. It is shown that the effective charge on the reactant is generally not the same as the nominal charge, but that it may be found on a basis of an analysis of the kinetic data together with the appropriate double layer data. In addition, the effective charge on the product is usually smaller than the nominal value. As a result, the analysis of the double layer effect involves the construction of corrected Tafel plots, which differ significantly from those described in the early work of Frumkin.