Blue Hierarchical TiO<sub>2</sub> Nanotube Array for Significantly Enhanced Electrochemical Oxidation Performance and Stability of Tetracycline Degradation
Yuqing Su, Zhen Yu, Ruonan Gu, Wei Wu, Shaoling Dai, Shaoan Cheng
Abstract
Blue TiO 2 exhibited excellent electrocatalytic activity for degrading various organic pollutants in wastewater. However, its crystal structure and morphology considerably affected the electrocatalytic activity of blue TiO 2 . In this study, a blue hierarchical TiO 2 nanotube array (B-HTNA) was synthesized utilizing Ti foam by ice–water bath anodic oxidation and cathodic reduction. Benefiting from a higher concentration of doped Ti 3+, the prepared B-HTNA exhibited greater electron transport capability. B-HTNA effectively degraded tetracycline with a high removal rate of more than 90% within 60 min under 20 mA cm –2 . The results of free radical quenching experiments revealed the effects induced under different experimental conditions, wherein the electrochemical oxidation of pollutants with B-HTNA mainly relied on the oxidation of hydroxyl radicals. In addition, B-HTNA exhibited a longer service life of up to 85.4 h, surpassing other anodes with a bare and fragile nanotube array. B-HTNA displayed enhanced stability owing to the hierarchical structure with uniform nanoparticles adhering to a porous layer, which could prevent chemical erosion of the anode and charge leakage from the top of the nanotube during cathodic polarization, thereby enhancing self-doping and stability.