Synthesis of Mesoporous Anatase TiO2 Sphere with High Surface Area and Enhanced Photocatalytic Activity

Mesoporous anatase TiO2 spheres with high surface area (119 m2 g−1) were successfully synthesized via a facile and green template-free method. The prepared TiO2 was characterized by X-ray diffraction (XRD), N2 adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis absorbance spectra. It was found that the prepared TiO2 is characterized by pure anatase phase, which shows uniform spheres and has a typical mesostructure with a high specific surface area and a large pore volume. The effects of complexant (acetylacetone) amount, crystallization temperature and calcination temperature were also investigated. Based on the results, a sketch for the preparation of mesoporous TiO2 was proposed. First, complex formed between tetrabutyl titanate and acetylacetone in ethanol. After introduction of aqueous of ammonia sulfate and urea, hydrolysis of tetrabutyl titanate would occur slowly, and sol of TiO2 was formed. Then, crystallization proceeded under hydrothermal conditions. Calcination process favored the formation of bigger TiO2 crystal through combining of the small crystals in TiO2. This led to the formation of bigger mesopores between TiO2 crystals. Photocatalytic activity of the prepared TiO2 was evaluated by decomposition of methyl orange.