Morphology-controllable synthesis and characterization of CeO2 nanocrystals

CeO2 nanocrystals with different morphologies were synthesized by adjusting the pH value of the starting solution in water-in-oil microemulsion. The obtained samples were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis and different thermal analysis (TGA/DTA), Brunauer-Emmet-Teller (BET) surface area measurement, ultraviolet-visible absorption (UV-vis) spectroscopy and photoluminescence (PL) spectroscopy. Results show that the morphologies of CeO2 were transformed from granular to spherical and to rod-like while the pH of the starting solution varied from 5 to 8 and to 11. All samples were indexed to the phase of CeO2 and Ce(OH)(4), and the molar ratio of CeO2 to Ce(OH)(4) was deduced to be about 0.25. The morphologies of CeO2 nanocrystals had but slight influence on their specific surface areas, UV-vis spectra and PL spectra. The band gap energies of different morphological samples were estimated by UV-vis spectroscopic method. (C) 2010 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.