Self-templating synthesis and photocatalytic activity of hollow TiO2 microspheres prepared by the sol–gel + solvothermal method

The microstructure of TiO2 hollow microspheres has a significant impact on the photocatalytic activity, especially the diameter, thickness, specific surface area and crystallinity, which are key factors for structure regulation. In this study, a self-template synthesis strategy for preparing hollow TiO2 hydrate microspheres by the sol–gel+ (methanol) solvothermal method was proposed. With the increase of the H2O/TBOT molar ratio (Rw) in the range of 0.75 ∼ 3.75, amorphous TiO2 colloidal microspheres with flower-like, hollow and solid structures of different sizes were prepared, and the control of TiO2 hydrate hollow microsphere diameters in the range of 1000 nm ∼ 1800 nm was realized. After calcination at 600 °C for 2 h, the structure was not damaged and had good crystallinity. TiO2 hollow spheres of Rw = 1.5 were used for ultraviolet photocatalytic degradation of 20 mg·L-1 phenol for 120 min, and the mineralization rate was >99%, which was better than P25. A series of analyses shows that under the experimental conditions, the hydrolysis rate can be controlled by regulating the H2O/TBOT molar ratio, which is the key factor in the synthesis of different structural sizes.