How Long Does It Take a Microelectrode To Reach a Voltammetric Steady State?

Though steady-state conditions offer a number of voltammetric advantages, the degree to which the steady state is attained is often in experimental doubt. A theoretical study of the long-time voltammetric behavior of microelectrodes leads to the conclusion that steady states are reached in similar times by potentiostatic and galvanostatic routes. For reversible processes, the time to reach the steady state is Independent of the position of the target point on the voltammetric wave, but for irreversible processes the steady state is attained much faster toward the bottom of the wave than near its plateau. Hemispherical and disk microelectrodes of equivalent size take the same length of time to reach steady states. Experimental confirmation is reported for the reversible oxidation of ferrocene in acetonitrile at a microdisk electrode.