We have developed theory for cyclic
(staircase) voltammetry (CSCV)
of a two step reversible charge transfer (EE) mechanism for redox
species with unequal diffusion coefficients at rough electrodes. The
various surface microscopies provide details of random morphology
of the electrode which is characterized through the power spectrum
in our theory. For the finite fractal electrode model, anomalous enhancement
and scan rate dependence of the CSCV or CV response is caused by fractal
dimension (D
H
), lower
length scale of fractality (
), and topothesy
length (
τ). The peak current corresponding
to both charge transfer steps is enhanced with an increase in roughness
of the fractal electrode (through increase in D
H
or
τ or decrease in
). The onset
and offset of the anomalous
regime is controlled by
τ and
, respectively.
Results show that the electrode
roughness has the potential to enhance the sensitivity of CSCV as
an analytical technique. This is due to a decrease in the difference
between the peak currents of two charge transfer steps and an increase
in the ratio of the peak to the valley (minimum existing between the
two peaks) current in the presence of roughness. Finally, we show
that not accounting for roughness in data analysis may cause errors
in estimation of composition, diffusion coefficient, improper assignment
of electrode mechanism, and so forth.