Simple Hydrothermal Synthesis of Ultra-Small Cerium Oxide Nanoparticles

Cerium oxide, CeO₂ nanoparticles (NPs) have been synthesized through various methods to achieve the desired physicochemical properties. However, high temperatures, pressure and long reaction time were involved. In this study, ultra-small CeO₂ NPs were successfully synthesized using the hydrothermal method but under a favourably low temperature (70 ℃) for 4 hours using cerium nitrate hexahydrate, Ce(NO₃)₃ • 6 H₂O and sodium hydroxide, NaOH as the precursors while deionized water was used as the solvent. The synthesized ultra-small CeO₂ NPs were characterized using field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), energy dispersive X-ray (EDX), ultraviolet visible (UV-Vis) spectrometer, Fourier transform infrared (FTIR) spectroscopy, X-Ray Diffraction (XRD) and Brunauer-Emmett-Teller (BET) method. The synthesized ultra-small CeO₂ NPs were determined to have an average particle size of 3.54 nm, crystallite size of 3.05 nm and a high specific surface area of 185 m² g^-1. UV-Vis spectrum also showed absorption peak at 310 nm and FTIR spectrum intense peak at 447.20 cm^-1 indicating the presence of CeO₂ NPs. FTIR, EDX and XRD diffraction pattern have proved that the synthesized CeO₂ NPs is of high purity. This study has successfully synthesized ultra-small CeO₂ NPs with optimal conditions of hydrothermal treatment at 70℃ for 4 hours and a percent yield of ~99%.