Fabrication of Titanium Dioxide Materials with Enhanced Optical Properties

Abstract

Photocatalysis has presented extensive opportunities for applications in environmental and industrial processes due to its ability to facilitate chemical transformations under light irradiation. Titanium dioxide (TiO₂), a widely utilised photocatalyst, offers advantages such as chemical stability, affordability, and high efficiency. However, its photocatalytic activity has predominantly remained limited to the ultraviolet (UV) region, constraining its performance under low energy UV, and natural sunlight. This study aimed to explore the strategies to modify titanium dioxide optical properties and study its photocatalytic behaviour under various illumination conditions. The study focused on Rhodamine B, Fluorescein, and Thionine dyes as organic chromophores, owing to their functional groups amino (–NH₂), carbonyl (–C=O), phenol (Ph–OH), and sulphur (S), which promote strong interaction with the TiO₂ surface and facilitate electron transfer.The solvothermal synthesis has been chosen to prepare TiO₂-dye nanocomposites in three media: i) ammonia solution, ii) acetic acid, and iii) formic acid to explore the influence of structural variations on optical properties. The characterisation by techniques such as powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) has been carried out to evaluate the physical, chemical, and optical properties of the synthesised composites. Photocatalytic performance has been assessed using methylene blue (MB) as a model pollutant under UV, visible, and UV-Vis irradiation conditions. The findings have indicated that dye-modified TiO₂ nanocomposites exhibit enhanced photocatalytic activity by improving light absorption and reducing electron-hole recombination. These results have suggested that the dye-TiO₂ nanocomposites could offer promising potential in addressing environmental challenges such as water purification and pollutant degradation. Future investigations could focus on exploring alternative sensitisation materials, optimising synthesis conditions, and integrating these composites into scalable applications to broaden their utility and impact in sustainable technologies.