Solvothermal synthesis and characterization of anatase TiO2 nanocrystals with ultrahigh surface area
Phase-pure, ultrafine nanocrystalline anatase with high specific surface area (up to 250 m(2) g(-1)) was obtained upon injection of a titanium alkoxide precursor into ethanol with designed volume of water under mild solvothermal conditions (<200 degrees C, 2 h). Primary particle sizes were tuned by adjusting various reaction parameters, with the smallest grain sizes occurring at low temperatures (140-150 degrees C), low initial alkoxide concentrations, and intermediate hydrolysis ratios (r identical with[H2O]/[Ti(OR)4]=5-10). Additionally, variations in the reaction temperature result in changes in particle morphology and distribution, with high-temperature samples exhibiting bimodal distributions of small spherical and larger cubic particles that suggest grain growth via Ostwald ripening. A crystalline product with high thermal stability and specific surface area up to 5 times that of commercial nano-titania can be obtained at a relatively low temperature of 150 degrees C. The physical properties of the titania samples obtained in this study suggest they might be well suited for catalytic applications.