Oxygen vacancy/Ti3+ engineered TiO2 nanotube arrays prepared by in-situ exfoliation with H2 bubbles: A visible-light-driven self-supporting photocatalyst for detoxfication of chloraphenicol.

Oxygen vacancy/Ti³⁺ engineered TiO 2 nanotube arrays were prepared through electrochemical strategy at high potential (−6 V). The electrons surging from DC power initiate the valance decline of Ti⁴⁺, and countless H 2 bubbles released from TiO 2 surface lead to the in-situ exfoliation of some TiO 2 tiny debris, generating point defects containing Ti³⁺ inside the TiO 2 and oxygen vacancy (OV) embedded on TiO 2. The generated Ti³⁺/ OV help TiO 2 to increase the harvest toward visible light and serve as active sites for activating molecular oxygen to form superoxide radical (·O 2 ^-). Besides, as improved separation of electron-hole pairs endowed by the defects, the yield of hydroxyl radicals (·OH) is enhanced compared with the pristine TiO 2. Chloramphenicol (CAP, an antibiotic) molecules can be efficiently degraded with the reduced TiO 2 under the visible light with its degradation and evolution pathway expounded in detail. Fukui index is employed to anticipate the probable sites that are subjected to oxidation by·OH and the MS spectra evidence that the·OH governs the decomposition routes of CAP molecules. ECOSAR simulation evaluates the toxicity of CAP and the intermediates, demonstrating that the final products from the photocatalysis do not post any hazardous risk on ecosystem. [Display omitted] • Oxygen vacancy/Ti³⁺ engineered TiO 2 nanotube arrays were constructed by in-situ exfoliation. • Oxygen vacancy and Ti³⁺ serve as intrinsic active sites. • Hydroxyl radicals govern the degradation pathway of CAP molecule. • Final products from the photocatalysis do not pose any hazardous risk on ecosystem. [ABSTRACT FROM AUTHOR]