current efficiency
If several reactions take place simultaneously at the electrode a partial electrode current density (c.d.) Math - text can be assigned to each reaction. It is given by the stoichiometry of the reaction and by the amount of substance of B reacting (per unit time and per unit electrode area) in the reaction considered. The current efficiency of reaction Math - text, Math - text is defined as the ratio of Math - text to the total c.d.:
Math - e
Note that Math - text may be larger than one if cathodic and anodic reactions take place simultaneously at the same electrode. However, Math - text still gives correctly the product yield, which is the quantity of industrial interest. The product yield is the amount of substance of B produced per unit charge and is equal to Math - ei (in the absence of a chemical reaction which is consecutive to the electrode reaction and which consumes or produces species B). Math - text is the charge number of electrode reactionMath - text. Note that in the case of simultaneous electrode reactions the distribution of the partial c.d. Math - text may be different from that of the total c.d., i.e. the function Math - ei may be different from Math - ei. In electroplating the term 'metal distribution' is sometimes used to designate the distribution Math - text of the partial c.d. for metal deposition.
PAC, 1981, 53, 1827 (Nomenclature for transport phenomena in electrolytic systems) on page 1836