Synthesis of Mixed-Phase TiO₂ Powders in Salt Matrix and Their Photocatalytic Activity

Abstract

Three mixed-phase TiO₂ powders, containing ∼80 volume % anatase and ∼20 volume % rutile, were prepared from amorphous titanium hydroxide and three different salt matrices—pure sodium chloride, pure Na₂CO₃, and pure disodium hydrogen phosphate (DSP). Amorphous titanium hydroxide and salt mixtures were heat treated at 875°C in a rapid thermal annealing system for different times, according to the time–temperature phase transformation graphs. Time-dependent UV degradation of aqueous solutions of methylene blue dye (15 ppm) in the presence of mixed-phase powders was used to monitor the activity of the catalysts. Microstructural study of the powders by scanning electron microscope and transmission electron microscope combined with phase analysis by XRD and optical absorbance by UV-absorption spectroscopy indicated that the higher photocatalytic activity of the powder obtained from pure DSP salt could be explained by its smaller rutile particle size and anatase–rutile interparticle bonding.

Keywords:

• Microstructure
• Molten
• Nano
• Photocatalyst
• Salt
• Synthesis
• TiO₂
• XRD

ACKNOWLEDGMENTS

The authors gratefully thank Birla Institute of Technology and Science (BITS-Pilani), Pilani Campus, and Indian Institute of technology (IIT), Kharagpur, for the support of this work.