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 m2 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≡[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 °C. The physical properties of the titania samples obtained in this study suggest they might be well suited for catalytic applications.

Graphical abstractMild solvothermal synthesis of nanoscale TiO2 in ethanol with designed volume of water produces phase-pure anatase with ultrahigh surface area and tunable physical properties.Figure optionsDownload full-size imageDownload as PowerPoint slide