Homogeneous precipitation of cerium dioxide nanoparticles in alcohol/water mixed solvents

In this work, the CeO2 nanoparticles were synthesized by homogeneous precipitation in alcohol/water mixed solvents. Six alcohols, including methanol, ethanol, n-propanol, iso-propanol, tert-butanol, and ethylene glycol (EG), were separately mixed with water as the solvents. The effects of nature and composition of alcohol on the resultant CeO2 nanoparticles were under investigation. From the experimental results, it is found that the CeO2 nanoparticles obtained from alcohol/water mixed solvent were primary particles confirmed by quite good consistency in the particle sizes from TEM, XRD and BET analyses. The results also reveal that the CeO2 nanoparticles are non-porous. Besides, no matter what kind of alcohol is used, the prepared CeO2 nanoparticles exhibit cubic fluorite structures. In pure water environment, the size of CeO2 particles is about 15 nm, whereas it reduces to about 7 nm in the 67% ethanol/water solution. Especially in the EG/water solvent system, the resultant samples are extremely smaller than those in other systems. As the vol.% of alcohol increases, the particle size decreases for all solvent systems, and the reverse, the specific surface area increases. This alteration in particle size can be approximately interpreted by the changes in electrostatic interactions and nucleation rate with varying the dielectric constant of mixed solvent.