current efficiency

If several reactions take place simultaneously at the electrode a partial electrode current density (c.d.) $j k$ 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 $k$ , $ɛ k$ is defined as the ratio of $j k$ to the total c.d.:

$ɛ k = j k ∑ m j m$

Note that $ɛ k$ may be larger than one if cathodic and anodic reactions take place simultaneously at the same electrode. However, $ɛ k$ 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 $ɛ k ν B , k n k F$ (in the absence of a chemical reaction which is consecutive to the electrode reaction and which consumes or produces species B). $n k$ is the charge number of electrode reaction $k$ . Note that in the case of simultaneous electrode reactions the distribution of the partial c.d. $j k$ may be different from that of the total c.d., i.e. the function $j k x j = f k x$ may be different from $j x j = f x$ . In electroplating the term 'metal distribution' is sometimes used to designate the distribution $f k x$ of the partial c.d. for metal deposition.

Source:

PAC, 1981, 53, 1827 (Nomenclature for transport phenomena in electrolytic systems) on page 1836

current efficiency

Also contains definition of: metal distribution