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

Ultrathin TiO2 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 center dot center dot center dot Ti-intermediates, resulting in the activation of ENR. OVs on NST can adsorb and activate more O2 molecules to accelerate the generation of O2- 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.

Automated summary

Ultrathin TiO2 nanosheets containing Ti3+ sites were used as a photocatalyst to degrade enrofloxacin (ENR) under visible light with a high efficiency of 98.6%. The higher degradation efficiency of ENR over NST is attributed to the increased Ti3+ and oxygen vacancies (OVs). Ti3+ sites on NST can form surface coordination intermediates with ENR molecules, activating ENR. The OVs on NST can adsorb and activate more O2 molecules, accelerating the generation of O2- by photogenerated electrons reduction. The photogenerated holes quickly transfer to the catalyst surface to directly degrade the activated ENR. A mechanism is proposed to explain the synergistic effect of coordination activation and photocatalysis over NST at a molecular level. This study emphasizes the important role of coordination activation in the photocatalytic degradation of antibiotics.