Recent interest in titanium dioxide (TiO₂) nanomaterials has been largely driven by the photocatalytic properties exhibited by the anatase and rutile phases. We have concentrated on the relationship between the synthetic pathways to TiO₂ and the properties of the resulting products, demonstrating that the control of the relative reactant diffusion rates during solvothermal reaction leads to the prediction and control of the phase, size and nanostructures type. This degree of control has made it possible for the systematic synthesis of TiO₂ nanostructures by varying parameters such as solvent chain length, reaction temperature and time, and the addition of surfactants into the reaction mixture. Each of these parameters has been found to play a distinct role in the synthetic mechanism and judicious variation allows for the tailoring of nanostructures, vital for the optimisation of nanostructure for specific photocatalytic applications.

The photocatalytic activity of the TiO₂ samples were evaluated by the photo-degradation of the organic dye methylene blue (MB) in aqueous solution with TiO₂ nanoparticles. We found no significant relationship between the particle size and the rate of MB degradation, despite the large difference in surface area of the photocatalyst. These studies also showed that whilst pure anatase samples degrade MB reasonably well, rutile samples were found to be inactive. In contrast, mixed-phase TiO₂ particles resulted in an increased rate of photo-degradation.

The custom synthesis of TiO₂ nanostructures can lead to significant differences in photocatalytic activities, making it of particular interest in tuning the properties of TiO₂ for potential applications.