A Facile Method for the Synthesis of Metal Oxide Nanoparticles in Supercritical Water: Optimized Procedure for Cerium Oxide

Abstract

Metal oxide nanoparticles have been used for numerous applications in industry. The cerium oxide (CeO2) NPs were synthesized in the supercritical water (SCW) using its nitrate salt as a precursor. The response surface methodology (RSM) with the central composite design (CCD) was used to model the data as well as to optimize the synthesis procedure. The effect of different process parameters including reaction temperature (400–500 °C), concentration of the precursor solution (0.1–0.5 M), and reaction time (20–100 min) on the crystallite size and yield of the synthesis was studied. The results suggest that the precursor solution concentration had a significant effect on both the crystallite size and the reaction yield, while the temperature and reaction time significantly affected the crystallite size and the reaction yield, respectively. The achieved optimal conditions for the synthesis of CeO2 NPs were 500 °C, a reaction time of 73.26 min, and an initial precursor concentration of 0.28 M, where a crystallite size of 21.19 nm and a yield of 87.53% were achieved.