Coordination activation enhanced photocatalytic performance for levofloxacin degradation over defect-rich WO3 nanosheets.

The defect-rich ultrathin WO 3 nanosheets are successfully prepared as photocatalysts via heating treatment for the pristine WO 3 nanosheets (NS) in vacuum (NSV) and N 2 atmosphere (NSN). The increment of degradation efficiencies of levofloxacin (LVX) over NS (49.9 %) <NSN (75.9 %) <NSV (84.3 %) under visible light is mainly due to the increase of oxygen vacancies (O VS). These O VS have the potential to generate more unsaturated W centers (Lewis acid sites) which are beneficial to activate the C O of carboxyl and the C-N of piperazinyl in LVX molecules via W ^... O C and W ^... N-C coordination. LC ^- MS result further demonstrates that the LVX molecules breakdown are mainly initiated by cleaving the activated C O and C-N bonds. More O VS can adsorb and activate more O 2 molecules which shall be converted to •O 2 ⁻ by photogenerated electron. The photogenerated holes are transferred on the catalysts surface to form •OH via oxidizing water or directly degrade the activated LVX molecules. Finally, a possible mechanism is proposed to understand the pathway for photocatalytic degradation LVX at molecular scale. This study highlights the significant role of coordination activation for the photocatalytic degradation of antibiotics. [Display omitted] • Defect-rich ultrathin WO 3 nanosheets (≈ 4.8 nm) are synthesized as an active photocatalyst for the efficient degradation of levofloxacin (LVX). • LVX molecules are activated on the catalysts via W ^... O C and W ^... N-C coordination, improving the degradation efficiency of antibiotics. • Oxygen vacancies can adsorb more O 2 molecules which is converted to •O 2 ⁻ by photogenerated electron reduction. • A mechanism is proposed to understand the pathway for photocatalytic degradation LVX at molecule scale. [ABSTRACT FROM AUTHOR]