Effect of preparation methods on the properties of titania nanoparticles: solvothermal versus sol-gel

Titania (TiO2) nanoparticles (NP's) have been prepared by solvothermal and sol-gel techniques using different surfactants such as acetic acid (AA), oleylamine (OM), and AA + OM. The solution was thermally treated at growth temperature 180 degrees C in solvothermal method. TiO2 powder, prepared using both methods, was subjected to post heat treatment at 550 and 950 degrees C. The effect of surfactants on the morphology of TiO2 NP's was studied by transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). The structural and thermal properties of titania NP's are investigated by means of X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, and differential scanning calorimetry (TGA/DSC). TEM and FESEM images illustrated various shapes of titania NP's such as irregular spherical, rounded rectangular, truncated rhombic, oval, and rod-like structure in presence of different surfactants. Moreover, TiO2 particles prepared by sol-gel method were almost 40 times greater than those prepared by solvothermal method. In addition to the improvement in the crystallinity, thermal stability has been enhanced due to consolidation of individual particles at higher annealing temperature in solvothermal technique. Furthermore, a reduction in the degradation temperature and phase transformation of TiO2 NP's were conspicuously corroborated after post-heat treatment.