Hydrothermal synthesis of flower-like hierarchical TiO₂ microspheres from titanium sulfate and hexafluorosilicic acid

Flower-like hierarchical TiO₂ microspheres assembled by nanosheets with exposed {001} facets were prepared through a cost-effective hydrothermal synthesis method, using cheap Ti(SO₄)₂ as the feedstock and hexafluorosilicic acid as the capping agent. These hierarchical microspheres were assembled by numerous and cross-linked nanosheets. The fine structure of hierarchical microspheres could be easily controlled by adjusting the concentration of hexafluorosilicic ions. The growth process of the microspheres was examined through XRD and SEM characterizations, and a possible formation mechanism was proposed. Compared with other solvothermal synthesis methods, this cost-effective hydrothermal synthesis route is attractive and can be potentially applied in the production of flower-like TiO₂ hierarchical microspheres in large scale. The as-prepared flower-like TiO₂ hierarchical microspheres exhibit good photocatalytic ability to degrade methyl orange dye.