Control synthesis and formation mechanism of sphere-like titanium dioxide

Using a simple hydrothermal method without surfactants and templates, different morphologies of titanium dioxide (TiO₂) have been synthesised such as nanocubes, nanosheets and microspheres. The effects of the addition of hydrofluoric acid (HF) and hydrogen peroxide (H₂O₂) in the preparation of TiO₂ were studied. It was found that more H₂O₂ may accelerate the formation of a spherical morphology and that HF has three roles: dissolving Ti powder, retarding the hydrolysis of titanium precursor and reducing surface energy. Reaction time has a significant effect on morphological transformation. The aggregation of microstructures is described, the effects of the addition of HF and H₂O₂ on the condition of aggregation have been studied. Photocatalysis measurements showed that sphere-like TiO₂ consisting of nanocubes exhibited the highest activity for degrading rhodamine B under UV light.