Controlled synthesis and optical properties of CeO2 nanoparticles by a N2H4[middle dot]H2O-assisted hydrothermal method

Abstract

Ceria (CeO2) nanoparticles were successfully synthesised by a novel hydrothermal synthesis process using Ce(NO3)3·6H2O as cerium source and hydrazine hydrate (N2H4·H2O) as mineraliser. The crystal phases, surface morphology and optical properties of CeO2 nanoparticles were characterised by X-ray diffraction, scanning electron microscope, UV-vis spectrophotometer and fluorescence spectrometer. The particle size (ranging from 10 to 20 nm) decreases with the increase of N2H4·H2O from 2 to 8 ml and its mechanism has been proposed and can be mainly attributed to the effect of N2H4·H2O on OH− ionic concentration in the solution. The lattice parameter (∼0.54 nm) decreases with the increase of the crystallite size that can be attributed to both lattice relaxation and valence effect of Ce ions. The absorbance in UV light region increases with the increases of N2H4·H2O from 2 up to 6 ml and then decreases when the dosage of N2H4·H2O is 8 ml. The bandgap energy increases from 3.13 to 3.23 eV with the increases of N2H4·H2O from 2 up to 6 ml because of electrostatic potential effect and then decreases to 2.97 eV when the dosages of N2H4·H2O is 8 ml. The emission intensity increases with the increase of N2H4·H2O from 2 ml up to 6 ml and then unobviously decreases when dosage of N2H4·H2O is 8 ml.