Synthesis, structural and optical properties of CeO2 nanoparticles synthesized by a simple polyvinyl pyrrolidone (PVP) solution route

This paper reports the synthesis and characterization of CeO2 nanoparticles by a simple polymer complex method using cerium (III)) acetate hydrate and polyvinyl pyrrolidone (PVP) as the starting chemicals. The precursor was calcined at 500 °C for 2 h to obtain CeO2 nanoparticles. The XRD, FTIR, Raman and electron diffraction analysis results indicated that the calcined CeO2 sample has the fluorite structure of CeO2. TEM revealed that the CeO2 sample consists of crystalline particles of 5–10 nm which are weakly aggregated. UV–vis spectroscopy was also performed to study the optical properties of the synthesized CeO2 sample. The sample exhibited a strong absorption below 400 nm (3.10 eV) with a well defined absorbance peak at around 285 nm (4.35 eV). The estimated band gap of the CeO2 sample was 3.44 eV and this value is higher than that of the bulk CeO2 powders (Eg = 3.19 eV) due to quantum confinement effect. The synthesized CeO2 nanoparticles also exhibited room temperature photoluminescence (PL). The spectrum of the CeO2 sample dispersed in methanol exhibits a broad-band character from 325 to 550 nm with four emission bands: a strong broad emission band at ∼406 nm (3.06 eV), a strong blue band at 420 nm (2.95 eV), blue-green band at ∼483 nm (2.57 eV), and a weak green band at 530 nm (2.34 eV). A peak centered at 406 nm for the CeO2 sample originates from the defect states existing extensively between the Ce 4f state and O 2p valence band.