Synthesis of Monodispersed rod-like and spherical CeO 2 particles by mild solution process

Abstract

Monodispersed rod-like and spherical ceria particles were successfully synthesized by a mild solution process followed by calcination treatment. The morphological control of cerium precursor was realized by using different cerium salts and precipitate reagents such as urea, hexamethylenetetramine and alkylamine. The effects of pre-aging temperature and time on the morphologies of final products were investigated in details. Monodispersed spherical precursor was obtained after pre-aging at 25 o C for 3 days, while rod-like cerium carbonate precursor was produced after pre-aging at 50 o C. Monodispersed rod-like cerium hydroxide precursor was formed by using triethanolamine as precipitant. Ceria particles with the same morphologies and similar particle size could be obtained after calcination in air at 400 o C. 1. Introduction Recently, synthesis of rare earth compounds with different morphologies such as nanoparticles, nanotubes, nanowires and nanorods has been drawn much attention due to their unique electronic, optical, chemical properties and their extensive applications in luminescent devices, optical communication and biochemical probes, etc[1-3]. Ceria is an important functional material with many attractive properties and has wide applications such as abrasives, oxygen sensors, solid electrolytes in solid oxide fuel cells, three-way automobile catalysts, ultraviolet absorbents, etc[4-8]. It is accepted that different morphologies of nanostructured materials exhibit unique physical-chemical properties which are different from those of bulk materials. In the past few years, well-defined ceria nanostructures with various morphologies such as nanoparticles[9,10], nanowires[9-11], flower-like structure[12], etc. have been successfully fabricated. Some novel applications such as water treatment and CO removal[12] photocatalyst[13] and normal catalyst[14] were also reported. In the present research, the morphological control of crystalline cerium oxide particles was realized by a mild solution process using different cerium salts and precipitate reagents such as urea, hexamethylenetetramine (HMT) and alkylamines followed by calcination in air at 400 o C. Monodispersed rod-like and spherical ceria particles were synthesized and characterized.