The i–V response of an electrochemical cell comprising two polarizable microelectrodes and the influence of impurities on the cell response

The steady-state i–V behavior of an electrochemical cell comprising two polarizable Au microelectrodes in a mixed redox solution containing reversible and soluble redox species (FcCH2OH and Ru(NH)63+) is reported. Analytical solutions describing the cell i–V response in the absence of a well-poised reference electrode are presented, and these expressions are shown to agree with the experimental i–V results. Depending on the relative areas of the electrodes, the i–V response in the absence of a reference electrode is particularly sensitive to the presence of redox impurities. Specifically, we demonstrate that FcCH2OH+ impurity in the solution yields diffusion limited current plateaus that are equal to the currents for the primary redox species present in nearly 100-fold excess.

► We describe the voltammetric response of a cell comprising two polarizable microelectrodes.
► The computed i–V response is in excellent agreement with experimental data.
► Impurity species dominate the behavior for cells with electrodes of unequal areas.