Different surfactants such as sodium dodecyl sulfate (SDS), polyethylene glycol (PEG), and cetyltrimethyl ammonium bromide (CTAB,) assisted cerium oxide (CeO2) nanoparticles were synthesized by using cerium chloride and potassium hydroxide as the starting materials via facile hydrothermal route. The powder X-ray diffraction (XRD) shows that cubic fluorite-type structure of pure CeO2 and the average crystallite sizes were calculated to be ~12–16？nm. Raman spectra of various surfactants assisted CeO2 consist of a single triply degenerated F2g mode characteristic of the fluorite structure. The elongated spherical-like morphology of SDS assisted CeO2 samples was observed from the SEM and TEM studies. Optical absorption spectra showed a blue shift by the capped CeO2 due to the quantum confinement effect. Photoluminescence (PL) emission studies shows that there is a change in the intensity of emission peaks by the capping agents, which indicates that the capping layers did result in size changes or increased surface defect. 1. Introduction Synthesis of nanomaterials with controlled morphology, size, chemical composition, and crystal structure, and in large quantity, is a key step toward nanotechnological applications [1]. Nanocrystalline cerium oxide (CeO2) materials have received much attention owing to their physical and chemical properties, which are markedly different from those of the bulk materials [2]. Ceria is an important rare-earth oxide with rapidly increasing applications in several fields due to its high refractive nature, strong UV absorption property [3], and high transparency in the visible and IR region [4]. Due to these properties, it has been widely used for a variety of applications such as fuel cells, gas sensors, NO removal, glass polishing material, and UV-blockers and filters [3–7]. It is well known that the new properties and applications of materials are related to their shapes and sizes [8]. Moreover, the morphology of the product can be controlled, through proper choice of the surfactants. A variety of methods, including spray pyrolysis, microwave-hydrothermal, sol-gel, and hydrothermal and chemical precipitation route, have been successfully used to create ceria nanoparticles [7–12]. Among the other methods, the hydrothermal approach is a better alternative with the advantages of the simplicity of the process, high purity, easy scaleup, narrow particle size distribution, chemical homogeneity, and low environmental pollution. Cationic, anionic, and nonionic surfactants can play an important role in synthesizing the nanomaterial in
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