Solvothermal synthesis of TiO2 with exposed (001) facets, mixed-phase and small particle size by using mixture of water and acetic anhydride as solvent. (21st December 2017) - Cao, Yue
Abstract: In this work, TiO2 nanoparticles with exposed (001) facets, mixed-phase and particle size as small as ∼20 nm were prepared via solvothermal process by using mixture of water and acetic anhydride as solvent and HF as shape directing agent. The as prepared TiO2 was characterized by X-ray diffraction (XRD), electron microscopes, elemental analysis (EA) and X-ray fluorescence (XRF), thermalgravimetric analysis and differential scanning calorimetry (TG-DSC), and nitrogen adsorption/desorption isotherms. The results indicated that the uncalcined sample which obtained after solvothermal process contained amorphous carbon, TiOF2, H2 Ti2 O5 ·H2 O, and Ti-containing organometallic compound. When calcined at temperature lower than 750 °C, a mixture of anatase and rutile was obtained. The photocatalytic activity of as prepared TiO2 was tested as H2 evolution rate from water containing methanol as sacrificial agent. The photocatalytic activity for TiO2 prepared by using H2 O/Ac2 O as solvent was about 6 times higher than that of sample prepared by using HAc as solvent. The H2 evolution rate over TiO2 sample prepared under optimum condition was 7.65 mmol·g -1 ·h -1, which was almost 50% higher than that of commercial P25. The influence of solvent, solvothermal temperature and calcination temperature on the morphology, particle size, phase composition and photocatalytic activity of as-synthesized TiO2 was discussed in detail. Graphical abstract: Highlights: (001) facets exposed anatase TiO2 with particle size as small as ∼20 nm was prepared. The mere change of solvent led to a 600% increase in photocatalytic water splitting activity of product TiO2 . The photocatalytic activity of TiO2 prepared under the optimum condition was ∼50% higher than that of P25.