RuO2-CeO2@Ti Anode for Electrocatalytic Degradation of Acid Orange 3: Performance Evaluation and Mechanistic Study

Acid Orange 3 (AO3) is a widely used azo dye in leather, paper, and textile dyeing. Untreated direct discharge into water bodies severely threatens human health and aquatic ecosystems, yet efficient degradation remains challenging for conventional technologies. In this work, RuO2/CeO2 heterostructure was synthesized and immobilized on a Ti substrate via controlled hydrothermal and annealing treatments, yielding RuO2/CeO2@Ti electrode. The electrode showed electrocatalytic activity for the oxygen evolution reaction (OER) over a wide pH range. Under optimized conditions (47 mA/cm2, pH 6, 0.25 M NaCl), 150 mg/L AO3 was degraded by 95.89% within 180 min. The degradation mechanism was elucidated by GC-MS and DFT (density functional theory) calculations. The degradation process was dominated by indirect oxidation, sequentially involving azo bond cleavage, heterocyclic ring opening, desulfurization, denitrification, benzene ring cleavage, and mineralization of small molecules into H2O and CO2.