Abstract. CeO 2 /ZnO composite nanoparticles are synthesized by using in-situ precipitation method, without any stabilizers, via conventional i.e. non-ultrasound (NUS) and ultrasound-assisted processing technique (US). The structure, morphology, particle size and % weight loss of the synthesized nanoparticles were analyzed by using X-ray powder diffraction (XRD), Thermogravimetric Analysis (TGA), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) to establish the formation of core shell type nanomaterials with an average particle size under 15 nm. The effectiveness of the synthesized core shell morphology of CeO 2 /ZnO (catalyst) for the photocatalytic degradation of Rhodamine B (RhB) dye has also been investigated. It has been observed that the catalysts prepared by sonochemical method exhibit higher photocatalytic activity as compared to the catalysts prepared by the conventional method. It was also found that the ultrasound-assisted technique is an energy efficient method as it saves more than 80% of energy along with a substantial reduction in reaction time, as compared to conventional synthesis technique.

Individual CeO2, ZnO and bimetal oxide core shell CeO2/ZnO composite nanoparticles are synthesized without any stabilizers using in-situ precipitation technique. The structure, morphology and particle size of the synthesized nanoparticles were analyzed by using X-ray powder diffraction, scanning electron microscopy and Transmission electron microscopy. Results reveal that the phase structures of CeO2/ZnO are composited by cubic (fluorite) phase of CeO2 and hexagonal (wurtzite) phase of ZnO. Structure characterization of core shell particles by Transmission electron microscopy indicates that the ZnO shell is around 5 nm in thickness and CeO2 core is 9 nm in diameter. The effectiveness of the synthesized CeO2/ZnO used as catalysts for the photocatalytic well as sonocatalytic degradation of Rhodamine B dye has also been investigated. The results showed that Photocatalysis was more efficient than sonocatalysis in degradation of Rhodamine B.