Precisely dominating oxygen vacancy of Magnéli phase titanium suboxides to efficiently remove quinolone antibiotics under visible light

Oxygen vacancy modulation is often applied to the modification of photocatalysts as a typical technique that affects the electronic structure, light absorption properties, and surface adsorption properties of semiconductor materials. Titanium suboxide, a titanium oxide rich in oxygen vacancies, is hardly ever used for photocatalytic degradation due to the difficulty of obtaining a single phase. In this study, the Magnéli phases Ti4O7 and Ti3O5 were used as novel photocatalysts exhibiting effective photodegradation of quinolone antibiotics. The removal rate of levofloxacin (LEV) by visible light irradiation of Ti4O7 and Ti3O5 reached 91.2% and 87.3%, superior to most of the titanium oxide photocatalysts reported in the literature, whereas the P25 presented a decomposition rate of 13.0%. This prominent effect is attributed to the contribution of oxygen vacancies extending the light response range and enhancing the separation efficiency of photogenerated carriers. Meanwhile, oxygen vacancies as electron trapping centers also reduce the recombination of photogenerated electron-hole pairs and enable the generation of superoxide radicals, which dominate photocatalysis. The reaction pathways and reusability of Ti4O7 photocatalysts for mineralization of LEV were further analyzed. The visible photocatalysis of P25 by photosensitization, which is different from the photocatalytic mechanism of titanium suboxide, was also verified. This work certifies that titanium suboxide materials have promising applications in photocatalysis.