Evaluating the Impact of Oxygen Evolution on the Electrochemical Degradation of Organic Pollutants using Commercial Ti/RuO 2 -IrO 2 Anodes

This work evaluates the impact of the oxygen evolution reaction (OER) mechanism with surface pH and the generation of specific active sites on the anodic oxidation of methyl orange (MeO), a model organic pollutant, using Ti/RuO₂-IrO₂ anodes. The competing kinetics of MeO oxidation and the parasitic OER are investigated under acidic conditions (pH between 1.5 – 5.0) and at various applied potentials (between 1.60 – 1.80 V vs RHE) using linear sweep voltammetry, chronoamperometry, and UV-visible spectrometry. Tafel slope analysis reveals that OER kinetics are faster at pH 1.5, with the rate-determining step (rds) shifting from the formation of the OOH • adsorbate to the formation of the OH • adsorbate as pH increases. The degradation of MeO follows pseudo-zero order kinetics, indicating that the process is limited by charge transfer and the generation of active surface sites (MO x+1 ). A significant decrease in Faradaic efficiency for MeO oxidation is observed with increasing potential, dropping from 29.2% to 13.1% as the parasitic OER becomes dominant. These results show how establishing boundary conditions can enable energy-efficient industrial scale-up, moving beyond simple removal percentages to demonstrate that poor selectivity at high current densities is an intrinsic kinetic limitation. Thus, this methodology allows the definition of viable operational windows for sustainable, large-scale degradation processes.