How does a reversible electrode respond in a.c. voltammetry? Part 2: solutions for the periodic current amplitudes

• Published in: Journal of solid state electrochemistry 2019-07, Vol.23 (7), p.2061-2071
• Main Authors: Myland, Jan C., Oldham, Keith B.
• Format: Article
• Language: English
• Subjects: Amplitudes; Analytical Chemistry; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Computer simulation; Condensed Matter Physics; Electrochemistry; Electrodes; Energy Storage; Fourier transforms; Mathematical models; Original Paper; Physical Chemistry; Sine waves; Time dependence; Voltammetry
• ISSN: 1432-8488; 1433-0768
• DOI: 10.1007/s10008-019-04238-0

In a.c. voltammetry, a programmed electrical potential—a linear ramp modulated by a sine wave of frequency ω and modest amplitude—is applied to the working electrode of a voltammetric cell. If the electrolyte solution contains a solute that undergoes a reversible electron exchange at the electrode, then the ensuing faradaic current incorporates two aperiodic components, together with a pseudosinusoidal component of every frequency that is an integer multiple of ω . An exact mathematical model is presented that predicts how the time-dependent amplitudes of each of these latter harmonic currents evolve during the experiment. This analytical model, which does not invoke simulation or Fourier transformation, is useful only at early voltammetric times, but a numerical scheme extends the solution to encompass the entire scan. Amazingly, the time-dependent amplitudes of the periodic currents match their semiintegrals in shape.