Effect of concentration and temperature on electrochemical oscillations during sulfide oxidation on Ti/Ta2O5–IrO2 electrodes

The impact of current density, concentration, and temperature on the potential oscillations observed during the anodic oxidation of sulfide on Ti/Ta2O5–IrO2 oxide electrodes is investigated. Electrochemical methods including: cyclic voltammetry, linear voltammetry, linear galvanic voltammetry, galvanostatic technique and electrochemical impedance spectroscopy are used in this study. The observed potential oscillations are caused by the periodic formation/removal of sulfur from the electrode surface. Increasing current density has the effect of increasing the frequency of oscillations as well as increasing the onset potential. Both increasing concentration and temperature gave rise to significant increases in current density prior to the onset of potential oscillations. The activation energy for electrochemical oxidation of sulfide was estimated from the temperature studies. Lifetime experiments were also conducted and demonstrated that potential oscillations have a detrimental impact on the electrode lifetime.