Different heat treatment of CeO₂ nanoparticle composited with ZnO to enhance photocatalytic performance

In this study, ZnO/CeO₂ nanocomposites were prepared with four variations of the molar ratio of ZnO to CeO₂ nanoparticles. Both ZnO and CeO₂ nanoparticles were synthesized using the sol-gel method at low temperature, followed by different heat treatments for CeO₂ nanoparticles. Thermal phase transformation studies of the CeO₂ nanoparticles were observed at annealing temperatures of 400-800°C. The complete crystalline structure of CeO₂ nanoparticles was obtained at an annealing temperature of 800°C. The structural and optical properties of all samples were observed using several characterization techniques, such as X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectroscopy, and Brunauer, Emmett, and Teller (BET) surface area analysis. The structural characterization results revealed that the prepared CeO₂ nanoparticles were quite crystalline, with a cubic structure. The photocatalytic activities of all samples were tested under visible irradiation. The obtained results showed that ZnO/CeO₂ nanocomposites with a molar ratio 1:0.3 exhibited the highest photocatalytic activity. Further understanding of the role of primary active species underlying the reaction mechanism involved in photocatalytic activity were carried out in controlled experiments by adding several scavengers. The detailed mechanism and its correlation with the properties of ZnO/CeO₂ nanocomposites were discuss. (paper)