F-containing TiO2 nanopowders are synthesized using simple wet processes (precipitation-based and hydrothermal) from ammonium hexafluorotitanate (AHFT, (NH4)2TiF6) as a precursor to apply as a photocatalyst for the degradation of rhodamine B (RhB). The surface properties of the prepared samples are evaluated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The results confirm that the synthesized anatase TiO2 has sphere-like shapes, with numerous small nanoparticles containing fluorine on the surface. The photocatalytic activity of F-containing TiO2 compared with F-free TiO2 is characterized by measuring the degradation of RhB using a xenon lamp. The photocatalytic degradation of F-containing TiO2 exhibits improved photocatalytic activity, based on the positive effects of adsorbed F ions on the surface.

In this study, TiO2 powders are synthesized from ammonium hexafluoride titanate (AHFT, (NH4)2TiF6) as a precursor by heat treatment. First, we evaluate the physical properties of AHFT using X-ray diffraction (XRD), particle size analysis (PSA), thermogravimetric analysis (TGA), and field-emission scanning electron microscopy (FESEM). Then, to prepare the TiO2 powders, is heat-treated at 300-1300oC for 1 h. The ratio of anatase to rutile phase in TiO2 is estimated by XRD. The anatase phase forms at 500oC and phase transformation to the rutile phase occurs at 1200oC. Increase in the particle size is observed upon increasing the reaction temperature, and the phase ratio of the rutile phase is determined from a comparison with the calculated XRD data. Thus, we show that anatase and rutile TiO2 powders could be synthesized using AHFT as a raw material, and the obtained data are utilized for developing a new process for producing high-quality TiO2 powder.