A typical procedure for synthesizing submicrometer and micrometer TiO2 spheres is as follows. Volumes of 0.47, 0.4, and 0.3 mL of valeric acid were injected into the 20 mL of ethanol respectively, and then 0.3 mL (1 mmol) of TTIP was added. The solution was then heated at 85 °C for 6 h under reflux in air.