Control over the morphology of TiO2 hierarchically structured microspheres in solvothermal synthesis

Hierarchically structured spherical TiO2 particles were synthesized in a two-step process. Firstly, amorphous spherical TiO2 precursor particles with narrow size distribution and good dispersibility were obtained by hydrolysis from Ti(SO4)2 using polyvinylpyrrolidone (PVP) as surfactants. The surface microstructures of the TiO2 precursors were modified in different solvothermal conditions. The results showed that lychee-like TiO2 crystals were formed using dimethylformamide (DMF) and Ethylene glycol (EG) solvents by solvothermal treatment at 180 °C for 2 h. When choosing cetyltrimethylammonium bromide (CTAB) as the surfactant, TiO2 crystals with an orange peel-like surface were obtained. The hierarchically spherical TiO2 showed good photodegradation rate in methylene blue (MB) solution under UV irradiation. These amorphous spherical TiO2 particles are also the precursors to form the similarly shaped perovskite titanate through A-site ion-exchange reactions.