CeO2 nanoparticles growth by chemical bath and its thermal annealing treatment in air atmosphere

A novel synthesis of CeO2 powder by using chemical bath (CB) as green method is presented. The process was completed by thermal annealing (TA) at 1000 °C during 2 h. CeO2 growth was confirmed by: X-ray diffraction (XRD), UV-vis spectra, Energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and Raman spectra. By FTIR, bands associated with CO32−and OH− ions were identified, disappearing with the TA process. The X-ray diffraction (XRD) patterns of the as grown and CeO2 TA samples showed the reflection characteristic of CeO2 structure with a cubic symmetric pattern. By XRD diffractograms the grain size calculated were ∼2.7 nm and ∼28.5 nm for as-grown and CeO2 TA samples, respectively. The grain size of ∼2.7 nm is the smallest among the reported values for CeO2. Absorbance of as-grown spectra showed three bands located at ∼382, ∼357 and ∼271 nm while the CeO2 TA sample displayed only two bands at ∼271 and ∼320 nm. Direct optical energy gap were Eg = 4.4 eV and Eg = 4.3 eV for as-grown and CeO2 TA samples, respectively, showing quantum size effect of CeO2 nanoparticles. Raman spectra indicated that the as-grown and CeO2 samples have the fluorite structure.