Kinetics and Mechanism of Efficient Degradation of Oxytetracycline by Fe-Decorated Ti₄O₇ Electrode

Oxytetracycline (OTC), a tetracycline antibiotic frequently detected in aquatic environments, poses persistent ecological risks due to its resistance to conventional biodegradation. In this study, a novel iron-modified titanium suboxide electrode (Fe/Ti₄O₇) was successfully developed via a facile high-temperature solid-phase reduction method, and its electrocatalytic performance for the removal of OTC from wastewater was systematically evaluated. X-ray photoelectron spectroscopy (XPS) analysis revealed that the introduction of the Fe²⁺/Fe³⁺ redox couple significantly enhanced the interfacial charge transfer kinetics of the electrode. Under optimized conditions (pH = 7, 100 mM Na₂SO₄, current density of 20 mA·cm^-2), the Fe/Ti₄O₇ electrode achieved 99.7% degradation of 10 mg·L^-1 OTC within 20 min, with a total organic carbon (TOC) removal efficiency of 76.4%. Notably, the electrode exhibited excellent long-term stability, maintaining a degradation efficiency of over 90% after 36 consecutive cycles, while reducing energy consumption by 44.1% compared to the pristine Ti₄O₇ electrode. This demonstrates that the Fe/Ti₄O₇ electrode not only achieves higher degradation efficiency but also reduces the energy consumption required for electrocatalytic pollutant degradation, which is crucial for the industrialization of electrochemical wastewater treatment. Mechanistic studies confirmed that hydroxyl radicals (•OH) were the dominant reactive species, and the oxygen evolution side reaction was effectively suppressed by broadening the operating potential window of the electrode. Furthermore, intermediate analysis and toxicity assessment demonstrated that the electrocatalytic process significantly mitigated the ecological risks associated with OTC and its transformation products. This study provides an effective strategy for the design of high-performance electrocatalysts and offers a viable technical pathway for the advanced treatment of antibiotic-contaminated wastewater.