current efficiency

Also contains definition of: metal distribution
If several reactions take place simultaneously at the electrode a partial electrode @C01452@ (c.d.) \(j_{k}\) can be assigned to each reaction. It is given by the @S06026@ of the reaction and by the @A00297@ 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.: \[ɛ_{k}=\frac{j_{k}}{\sum _{\begin{array}{c} m \end{array}}j_{m}}\] 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 @A00297@ of B produced per unit charge and is equal to \(\frac{ɛ_{k}\ \nu _{B,k}}{n_{k}\ F}\) (in the absence of a @C01033@ which is consecutive to the @E01960@ and which consumes or produces species B). \(n_{k}\) is the @C00993@ of @E01960@ \(k\). 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 \(\frac{\left(j_{k}\right)_{\text{x}}}{j}=f_{k}\left(x\right)\) may be different from \(\frac{j_{\text{x}}}{j} = f(x)\). In electroplating the term 'metal distribution' is sometimes used to designate the distribution \(f_{k}\left(x\right)\) of the partial c.d. for metal deposition.
PAC, 1981, 53, 1827. (Nomenclature for transport phenomena in electrolytic systems) on page 1836 [Terms] [Paper]