Construction of titanium-based nanomaterials with a coral-like HTiOF3 template and their photocatalytic performance

Recently, the treatment of wastewater to remove antibiotics, such as oxytetracycline hydrochloride (OTC), has attracted much attention. In this work, coral-like HTiOF3 was used as a template to construct the small-scale nanomaterials {001}-TiO2, TiOF2/HTiOF3, and F-H2Ti3O7via different solvothermal methods. The crystal forms, structures, morphologies, optical properties, and charge separation properties of the obtained materials were thoroughly characterized using several techniques. Of these materials, F-H2Ti3O7 (KOH-HTF), synthesized via an alkali thermal synergistic ion exchange method, showed excellent OTC degradation activity (92%). The three-dimensional (3D) flower-like morphology of KOH-HTF enhances its OTC adsorption capacity. The co-modification of lattice fluorine and surface fluorine introduced in situ during the preparation of KOH-HTF brings a significant surface fluorine effect, which is not only conducive to the generation of Ti3+ and oxygen vacancies (Vos), but also conducive to the activation of OTC molecules and the migration of photogenerated electrons and holes. In addition, O2− has been proven to be the main active species in the photocatalytic process. It is proposed that the ligand-to-metal charge transfer effect between KOH-HTF and OTC is the key to improving the visible light response and carrier separation. A possible photocatalytic mechanism is also investigated.