Solvothermal synthesis and characterization of anatase TiO 2 nanocrystals with ultrahigh surface area

Abstract

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 °C, 2 h). Primary particle sizes were tuned by adjusting various reaction parameters, with the smallest grain sizes occurring at low temperatures (140–150 °C), low initial alkoxide concentrations, and intermediate hydrolysis ratios ( r ≡ [H 2O]/[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 °C. The physical properties of the titania samples obtained in this study suggest they might be well suited for catalytic applications.