Non-Faradaic Processes. Capacitive Currents

Based on the way in which an electrode process has been illustrated, until now it would seem reasonable to assume that the only source of electron flow between the electrode and the species in solution might be attributed to faradaic processes of the type Ox + e = Red. It has already been mentioned in Section 2.3, however, that non-faradaic currents exist. Let us discuss their origin. 

When a difference of potential AE is applied to the two plates, an excess q of electrons accumulates on one of them (which is equal to the 

AE = the difference of potential applied between the two plates (in volts), 

In other words, when one applies a difference of potential between the two plates of a capacitor, a current flows through the circuit until the capacitor is charged this current is called the capacitive current. 

This is just what happens in an electrochemical cell when a potential is applied between the working and the reference electrodes the double layer setting up at the working electrode/solution interface generates capacitive currents. 

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