Electrochemical noise analysis on multiple dissimilar electrodes: Theoretical analysis

► A method for analyzing the electrochemical noise produced by multiple dissimilar electrodes is presented. ► The introduction of the concept of virtual electrode reduces the analysis to the case of two dissimilar electrodes. ► The use of two dissimilar pairs of identical electrodes enables estimation of the electrode impedances. The electrochemical potential and current noise generated by multiple electrodes are analyzed by considering the current flowing across each electrode and the electrochemical potential of the electrode array. By introducing the concept of a “virtual electrode”, the analysis of the electrochemical noise generated by an array of electrodes is reduced to the case of two dissimilar electrodes. For each electrode, an apparent impedance, Zρ*, can be determined as the square root of the power spectral density of potential divided by the power spectral density of the individual electrode current. When two dissimilar pairs of nominally identical electrodes are used and it is possible to assume that the pair of electrodes corroding more produces higher noise levels and displays lower impedance, the actual electrode impedance can be obtained with acceptable precision from the value of the nominal impedance. Further, the asymmetry between the two dissimilar pairs can also be quantitatively evaluated.