Visible-light-driven N-doped TiO/BiOI heterojunction with synergistic dual-active-sites for ofloxacin degradation: Combined theoretical and experimental insights.

Due to the increasing levels of ofloxacin (OFL) in environmental waters, the urgent need for ofloxacin removal has also received more attention. In this study, an N-doped N-TiO/BiOI visible light catalyst was prepared to remove residual ofloxacin from water by its photocatalytic properties. According to the characterization and experimental results, the doping of non-metallic nitrogen elements improved the photocatalytic performance of the catalyst. The degradation result illustrates that 94.65 % of OFL was degraded under simulated natural light (500 W xenon lamp) using a catalyst dosage of 0.3 g/L, with an initial OFL concentration of 5 mg/L at pH 7.0. It showed that the mechanism of the photocatalyst N-TiO/BiOI degrading OFL under visible light was mainly related to free radicals: superoxide radicals (•O) generated by the conduction band of N-TiO, the holes and hydroxyl radicals (•OH) produced at the valence band of N-TiO and BiOI, these active species, oxidize them to inorganic acids, CO and HO by continuously cleaving the bonds of the OFL molecule. During this process, the bonds connecting the carboxyl and methyl groups in the OFL are preferentially broken. The theoretical analysis of the photocatalytic performance and degradation mechanism of the catalyst is consistent with the experimental results. Moreover, N-TiO/BiOI maintained high photocatalytic activity after five cycles.