Controllable synthesis of TiO₂ nanoparticles and their photocatalytic activity in dye degradation

Titanium dioxide nanoparticles were synthesized by hydrolyzing titanium tetrachloride (TiCl₄) in a controlled manner using a homemade glass apparatus. The structural properties and chemical composition were studied using X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, Brunauer-Emmett-Teller surface area analysis, selected area electron diffraction, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. The X-ray diffraction pattern and the high-resolution transmission electron microscope analyses confirmed that the TiO₂ nanoparticles are composed of photo-active anatase and brookite phases. The photocatalytic activity of the TiO₂ nanoparticles was demonstrated by photo-degradation of methylene blue and congo red under UV–Vis light illumination. Studying how pH affects the degradation of methylene blue revealed that its photocatalytic degradation on TiO₂ nanoparticles is more efficient under alkaline conditions, whereas the congo red degradation is more efficient under acidic conditions.