Improving photocatalytic degradation of enrofloxacin over TiO2 nanosheets with Ti3+ sites by coordination activation.

Ultrathin TiO 2 nanosheets (NST) containing Ti3+ sites are developed as a photocatalyst that exhibits high degradation efficiencies (98.6%) for the degradation of enrofloxacin (ENR) under visible light. The increment of degradation efficiencies for ENR over NST is mainly due to the increase of Ti3+ and oxygen vacancies (OVs). Ti3+ sites on the surface of NST can be associated with ENR molecules through the formation of surface coordination species -COO∙∙∙Ti- intermediates, resulting in the activation of ENR. OVs on NST can adsorb and activate more O 2 molecules to accelerate the generation of O 2 - by photogenerated electrons reduction. The photogenerated holes quickly transfer to the surface of the catalyst to directly degrade the activated ENR. Finally, a possible mechanism about the synergistic effect of coordination activation and photocatalysis is proposed over NST at a molecule level. This study highlights the significant role of coordination activation in the photocatalytic degradation of antibiotics. [Display omitted] • TiO 2 nanosheets with Ti3+ sites and oxygen vacancies are synthesized for the efficient degradation of enrofloxacin (ENR). • ENR molecules are activated on the catalysts via surface -COO∙∙∙Ti- coordination species. • O 2 molecules can be adsorbed and activated on oxygen vacancies to generate O 2 - by photo-generated electron reduction. • A synergistic mechanism of coordination activation and photocatalysis is proposed. [ABSTRACT FROM AUTHOR]