Synthesis and characterization of thermally stable large-pore mesoporous nanocrystallineanatase

Thermally stable mesoporous nanocrystalline ТiО2 with a pure anatase structure was obtained by sol–gel synthesis (in combination with hydrothermal treatment) using titanium tetrabutoxide and dibenzo-18-crown-6 as a structure-directing agent in presence of surfactant and/or La3+ ions additives. Nanocrystalline TiO2 demonstrates various textures with a well-defined spherical morphology (micro- and nanospheres), a crystallite size of no greater than 10 nm (XRD), and a narrow pore size distribution. Spherical particles of micrometer scale in the presence of La3+ ions do not form. TiO2 calcined (at 500 °C) after hydrothermal treatment (at 175 °C) has a significantly more developed porous structure as compared with TiO2 which was not treated hydrothermally. For example, specific surface area amounts 137 m2 g−1 and 69 m2 g−1, pore volume 0.98 cm3 g−1 and 0.21 cm3 g−1, pore diameter 17.5 nm and 12.5 nm respectively for samples hydrothermally treated and not treated.

Graphical abstractLarge-pore mesoporous nanocristalline anatase.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Large-pore mesoporous nanocrystalline TiO2 was obtained by sol–gel synthesis. ► Crown ether was used as template in presence of surfactant and/or La3+ ions. ► Anatase (crystalline size<11 nm) is the only crystalline phase present in TiO2. ► TiO2 shows well-defined homogeneous spherical morphology (micro- and nano-spheres).