Facet effect of TiO2 nanostructures from TiOF2 and their photocatalytic activity

•Different TiO2 nanostructures were prepared from TiOF2 precursor.•The effect of the particles shape on phenol mineralization was investigated.•The (101) anatase surface was found to be more suitable for TOC removal than (001).•HF induced surface formation of TiO2–x additionally lowered TOC mineralization.•Formation of ortho-hydroxylated phenol was found to depend on the (001) presence. In this study, special attention is focused on the design of TiO2 morphology and microstructure in the two-step preparation procedure using TiOF2 as a precursor to study their photodegradation mineralization efficiency. Firstly, TiOF2 was synthesized by a simple solvothermal method using titanium(IV) tetrafluoride, which was further used as aprecursor in preparation of anatase 2D nanosheets, octahedral, decahedral, and rectangular prisms shape structures. The as-obtained nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller surface area analysis (BET), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy and photoluminescence spectroscopy. It was assumed that TiOF2 could be applied as a useful precursor for the preparation of nanostructured TiO2 with defined morphology. Simple controlling of the reaction environment, together with the stabilizing effect of the introduced substrates, resulted in the formation of TiO2 particles with different morphologies and consequently exposed crystal facets. The presence of {001}, {101} and {100} facets influence on their photocatalytic activity but mostly on their mineralization efficiency and the pathway of phenol degradation. From the obtained series, the TiO2 octahedra exposing {101} facets exhibited the highest photoactivity and mineralization efficiency under UV–Vis light irradiation, which decreases as the other facets appear and become more exposed. The obtained results were compared with a computational study on the ∙OH and ∙O2– attack on the phenyl ring. Overall results showed that the surface effects of the photocatalyst could be an influencing factor in both mineralization efficiency and photodegradation products formation.