Mechanism and Performance of Electrocatalytic Oxidation on RuO₂-IrO₂@Ti Anode in Alkaline Phenol Wastewater

Phenol, a highly biotoxic organic pollutant, is widely present in alkaline wastewater from industries such as petrochemical and coking plants. However, its efficient degradation remains challenging with existing technologies. In this study, a RuO₂-IrO₂@Ti electrode was fabricated by a coating method, achieving an oxygen evolution potential of 2.0 V vs RHE (Reversible Hydrogen Electrode). Under alkaline conditions (pH = 10) with optimized operating parameters (38 mA/cm² current density and 0.25 M NaCl electrolyte), the degradation efficiency of 125 mg/L phenol reached 92.33% within 180 min. Mechanistic investigations, including radical quenching experiments, GC-MS analysis of intermediates, and Fukui function-based reactive site analysis, confirmed that indirect oxidation dominated the degradation process. The primary degradation pathway involved electrophilic substitution by ClO^-, synergistically enhanced by oxidation via superoxide radicals (^•O₂ ^-). The electrode exhibited outstanding stability, maintaining a degradation efficiency of 90% after 30 consecutive cycles, while the electrochemically active surface area (ECSA) increased from 0.17 cm² to 0.44 cm², demonstrating its potential for industrial applications.