Blue Hierarchical TiO₂ Nanotube Array for Significantly Enhanced Electrochemical Oxidation Performance and Stability of Tetracycline Degradation

BlueTiO(2) exhibited excellent electrocatalytic activityfor degrading various organic pollutants in wastewater. However, itscrystal structure and morphology considerably affected the electrocatalyticactivity of blue TiO2. In this study, a blue hierarchicalTiO(2) nanotube array (B-HTNA) was synthesized utilizingTi foam by ice-water bath anodic oxidation and cathodic reduction.Benefiting from a higher concentration of doped Ti3+, theprepared B-HTNA exhibited greater electron transport capability. B-HTNAeffectively degraded tetracycline with a high removal rate of morethan 90% within 60 min under 20 mA cm(-2). The resultsof free radical quenching experiments revealed the effects inducedunder different experimental conditions, wherein the electrochemicaloxidation of pollutants with B-HTNA mainly relied on the oxidationof hydroxyl radicals. In addition, B-HTNA exhibited a longer servicelife of up to 85.4 h, surpassing other anodes with a bare and fragilenanotube array. B-HTNA displayed enhanced stability owing to the hierarchicalstructure with uniform nanoparticles adhering to a porous layer, whichcould prevent chemical erosion of the anode and charge leakage fromthe top of the nanotube during cathodic polarization, thereby enhancingself-doping and stability.