Preparation of ordered mesoporous F-H2Ti3O7 nanosheets using orthorhombic HTiOF3 as a precursor and their highly efficient degradation of tetracycline hydrochloride under simulated sunlight

In this study, the transformation relationship between HTiOF3 and TiOF2 under hydrothermal conditions was discussed first. With the progress of hydrothermal reaction, HTiOF3 with small hexagonal structure gradually transformed into TiOF2 with large cubic structure. Secondly, the effects of alkaline hydrothermal treatment and ion-exchange treatment on the phase and morphology of HTiOF3 and TiOF2 were investigated. It was confirmed that hexagonal HTiOF3 can be used as precursor to prepare fluorine doped H2Ti3O7 (F-H2Ti3O7) nanosheets with ordered mesoporous structure by simple alkaline hydrothermal and ion-exchange methods. The prepared F-H2Ti3O7 nanosheets have ordered mesoporous structure, providing a high specific surface area of 404.08 m(2)/g and a macroporous volume of 0.46 cm(3)/g. F-H2Ti3O7 can be adsorb tetracycline hydrochloride (TCH) on its surface and then degraded it via photocatalytic processes. Furthermore, herein for the first time the photocatalytic degradation path of TCH by F-H2Ti3O7 through the synergistic effect of sensitization and LMCT was proposed. Besides, the reusability study showed that F-H2Ti3O7 has the ability to degrade the tetracycline hydrochloride efficiently after five cycles and slightly its high degradation rate change from 92.90% to 82.10% under simulated sunlight. In addition, F-H2Ti3O7 has good sedimentation performance, which provides the possibility for the practical application of the photocatalyst.