Chemometrics assisted resolving of net faradaic current contribution from total current in potential step and staircase cyclic voltammetry

Numerical Resolving of Net Faradaic Current in Fast-Scan Cyclic Voltammetry Considering Induced Charging Currents

In this paper, we study theoretically and experimentally the effect of induced charging currents on the fast-scan cyclic voltammetry. As explained in this paper, the phenomenon originates from the coupling between faradaic and capacitive currents in the presence of uncompensated resistance. Due to the existence of induced charging currents, the capacitive contribution to the total current is different from the capacitive current measured in the absence of electroactive species. In this paper, we show that this effect is particularly important when the ratio of the capacitive current and the total current is close to unity, even for a relatively low cell time constant. Consequently, the conventional background subtraction method may be inaccurate in these situations. In this work, we develop a method that separates the faradaic and capacitive currents, combining simulation and experimental data. The method is applicable even in the presence of potential-dependent capacitance. The theoretical results are compared with some previously reported results and with experiments carried out on the potassium ferrocyanide/ferricyanide redox couple. Platinum disk electrodes of different diameters and NaClO₄ support electrolyte of different concentrations were used to obtain different cell time constants. The proposed method allowed us to separate the real capacitive current even in the situations where the conventional background subtraction used in many published papers is clearly inappropriate.