Morphological evolution for CeO2 nanoparticles synthesized by precipitation technique

In this article, the morphological evolutions of crystalline CeO2 nanoparticles prepared by isothermal and 2-stage non-isothermal precipitations are presented. Also, this paper demonstrates a simple way to obtain differently shaped CeO2 nanoparticles by adjusting the reaction temperature course. The morphology and structure of the resulting products are characterized by TEM, HRTEM, ED and XRD techniques. Furthermore, the particle formation mechanisms under different reaction conditions are also investigated. The experimental results show that the initial Ce(OH)3 precipitate plays an important role on determining the morphology and structure of the final products. At the earlier stage of precipitation, the Ce(OH)3 precipitates are sphere-like at 0 °C, but are needle-like at 90 °C. By either isothermal or non-isothermal precipitations over the studied conditions, most of the final products with size of 6.9-23.3 nm are particulate, e.g., sphere-like or hexagonal. However, needle-like CeO2 particles can only be achieved by the proposed 2-stage non-isothermal precipitation via topotactic mechanism.