Synthesis of large-pore mesoporous nanocrystalline TiO2 microspheres

Thermally stable mesoporous nanocrystalline TiO2 with strongly pronounced spherical morphology was obtained in the presence of crown ether as structure-directing agent using sol–gel synthesis in combination with hydrothermal treatment. Introduction of small amount of surfactant additive to reaction mixture leads to increasing degree of crystallization and modification of texture of titanium oxide. Anatase is the only crystal phase formed at calcination temperatures up to 500°C. The samples were characterized by XRD, SEM, TEM, and nitrogen adsorption–desorption methods. Microspheres with diameters ranging from 1.8 to 2.3μm are assembled by aggregation of spherical particles (~45nm) that were actually formed by primary spherical anatase particles with average crystallite size 8.3nm. The specific surface area of nanocrystalline TiO2 is 120m2/g with a pore size of 11.3nm and pore volume of 0.34cm3/g. [Display omitted] ► Mesoporous (11.3nm) nanocrystalline anatase microspheres (≈2μm) were obtained. ► Anatase microspheres consist of aggregates of spherical crystallites (10nm). ► Addition of surfactant increases degree of crystallinity and modifies texture.