Simulation of impedance spectra of oxalic acid electroreduction to glyoxylic acid: effect of chemical activator, pH, activation energy, and reduction potential


Abstract: The aim of this study was to examine qualitatively the effect of important electrochemical parameters on the faradaic impedance spectra of oxalic acid electroreduction. The impedance spectrum of a 3-step oxalic acid electroreduction mechanism was simulated by the solution of a faradaic impedance equation based on 3 state variables. Before the solution of the faradaic impedance equation, the electroreduction mechanism was analyzed and it was seen that this mechanism can be represented by an electrical circuit composed of 2 resistors and a capacitance or inductance. The effect of chemical activator on the impedance spectrum was determined by using the relation between topological indices and electrode potential given in the literature. Simulation results indicated that the increase in the alkyl chain length in the chemical activator has a minor effect on the charge transfer resistance. On the other hand, pH drop could have a significant effect on the reduction in charge transfer resistance. In addition, inductive behavior can be seen if the electroreduction of adsorbed oxalic acid becomes the rate limiting step.

Keywords: Oxalic acid, glyoxylic acid, electroreduction, impedance

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