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 300-1300°C for 1 h. The ratio of anatase to rutile phase in TiO₂ is estimated by XRD. The anatase phase forms at 500°C and phase transformation to the rutile phase occurs at 1200°C. 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.

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• Photocatalytic activity of rutile TiO2 powders coupled with anatase TiO2 nanoparticles using surfactant
  Jong Min Byun, Chun Woong Park, Young In Kim, Young Do Kim
  journal of Korean Powder Metallurgy Institute.2018; 25(3): 257.     CrossRef