Structural and Optical Properties of CeO 2 Nanoparticles Synthesized by Modified Polymer Complex Method

Abstract

Ceria nanoparticles (Ceria-NPs) were synthesized using a modified polymer complex method and their structural and optical properties were evaluated. The solids were heated at 550 °C and characterized using Raman, UV?Vis absorption, diffuse reflectance, X-ray photoelectron and photoluminescence spectroscopies, X-ray diffraction (XRD) and scanning and transmission electron microscopy. The primary particles obtained presented a size of ~ 10 nm. The XRD indicated that CeO 2 was the only crystalline phase. From the UV?Vis and diffuse reflectance spectra, energy values of 3.8 eV and 3.4 eV were obtained, values that can be associated with band?band electronic transitions and/or with those that involve ionized states located within the gap caused by defects and isolated atoms of Ce 3+ . Photoluminescence spectra reiterated the existence of localized states in the gap. Raman spectra revealed the existence of peroxide (O 2 2− ) and superoxide (O 2 − ) over the surface of the ceria-NPs. The XPS results indicated that the concentrations of Ce 3+ and Ce 4+ were ∼ 20.5% and ∼79.5% respectively, and that the stoichiometry of oxygen was 1.9 per atom of Ce. The results obtained from the characterization of CeO 2 -NPs synthesized make it as promising material for environmental remediation, biomedicine, gas sensing and optoelectronic applications.