Photoelectrocatalytic Oxidation of Diuron in Ethanol: Performance, Synergy, and Toxicity Assessment of Ti‐Based Mixed‐Metal‐Oxides Anodes

This work evaluates Ti/Ti 0.7 Ru 0.3 O 2 , Ti/Ti 0.7 Ir 0.3 O 2 , and Ti/Ti 0.7 Nb 0.3 O 2 mixed‐metal‐oxide (MMO) anodes for the degradation of the herbicide diuron in a non‐aqueous ethanolic medium using electrocatalysis, photocatalysis, and photoelectrocatalysis. Except for the commercial Ti/RuO 2 DSA, all anodes were prepared by thermal decomposition and characterized by XRD, UV–Vis DRS, and FEG‐SEM/EDS to correlate crystalline, optical, and morphological features with electrochemical behavior. Degradation performance was assessed by removal efficiency, pseudo‐first‐order kinetics, synergy index, and energy consumption. Electrocatalysis, Ti/RuO 2 , achieved the highest diuron removal (60.3%). Under photocatalytic conditions, removals of 98.2%, 87.2%, and 91.5% were obtained for Ti/RuO 2 , Ti/IrO 2 , and Ti/Nb 2 O 5 , respectively. Photoelectrocatalysis, Ti/RuO 2 , and Ti/IrO 2 reached 98.5% and 98.2% removal, whereas Ti/Nb 2 O 5 attained only 78.6%, indicating limited benefit from process coupling due to poor conductivity. Only Ti/IrO 2 exhibited a pronounced synergistic effect (SI = 1.45), enhancing degradation kinetics without additional energy demand, while Ti/RuO 2 and Ti/Nb 2 O 5 showed non‐synergistic behavior (SI < 1). LC–MS revealed several intermediates, including ethoxylated and hydroxylated species and the more toxic 3,4‐dichloroaniline, suggesting that high degradation efficiency is not directly correlated with a reduction in ecotoxicological risk. Overall, Ti/RuO 2 is an efficient benchmark, and Ti/IrO 2 is a promising MMO for ethanol‐based photoelectrocatalytic treatment when toxicity evolution is carefully monitored.