Mechanism of methylene blue degradation by three-dimensional particle electrodes: contribution of surface-bound radicals and direct electron transfer

In this study, Ti-Sn-Sb/γ-Al₂O₃ particle electrodes were prepared by sol–gel method and a three-dimensional electrocatalytic system was constructed to treat methylene blue (MB) dye wastewater. The experimental results demonstrate that the degradation of methylene blue conforms to the pseudo-first order reaction kinetics and had a low activation energy (E_a = 36.97 kJ/mol). Through quenching experiments, linear voltammetry tests, and radical trapping experiments utilizing benzoic acid as a probe, we have determined that the oxidation of MB by the particle electrode is primarily induced through direct surface electron transfer (86 ~ 88%) and surface-bound radicals (12 ~ 14%).

Methylene blue undergoes degradation through the synergistic interplay of direct electron transfer (86% ~ 88%) and surface-bound radicals ·OH_ads (12% ~ 14%) on the particle electrode’s surface.