Controllable synthesis and formation mechanism of 3D flower-like TiO₂ microspheres

The high recombination rate of electrons and holes has been one of the important reasons for limiting photocatalytic efficiency. In order to improve the photocatalytic performance, the reduction of the recombination probability can be achieved by regulating the morphology of the microspheres. 3D flower-like TiO₂ microspheres were successfully prepared by a one-step hydrothermal method using tetrabutyl titanate (TBT) as titanium source, glacial acetic acid (HAc) as solvent and capping agent. The TiO₂ microspheres were analyzed by XRD, SEM, and N₂ adsorption–desorption isotherm for structure and morphology characterization. The results show that the samples were self-assembled by nanosheets to form the anatase TiO₂ microspheres with mesoporous structure and the surface area of TiO₂ can reach 356 m²/g. As the heat treatment temperature increases, the nanosheets were destroyed. The methylene orange (MO) was degraded 99% in 2 h, and the catalyst could be reused many times over. The formation mechanism of flower-like TiO₂ microspheres was discussed in detail based on the above investigations.