RESUMO

The current study is focused on the systematic characterization and catalytic evaluation of ceria (CeO₂) nanorods (NRs) and zinc oxide (ZnO) nanoparticles decorated on CeO₂ nanorods (i.e., ZnO/CeO₂ NRs) for CO oxidation. Pure CeO₂ NRs were successfully synthesized by a hydrothermal method, and the ZnO nanoparticles were deposited following the wet-impregnation method. The crystalline structure, morphology, composition, and surface physicochemical properties of the investigated catalysts were systematically characterized by various analytical techniques. X-ray diffraction studies confirmed doping of a few amounts of Zn²⁺ ions into the CeO₂ lattice. More oxygen vacancies were formed in the ZnO/CeO₂ NRs as evidenced by Raman and photoluminescence studies. Transmission electron microscope images revealed that ZnO nanoparticles (~ 6.5 ± 0.5 nm) were well dispersed along the edges of the CeO₂ NRs. This significant decoration led to enhanced reducibility of ZnO/CeO₂ NRs, as indicated by the H₂ temperature-programmed reduction results. According to the ultraviolet-visible diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy results, ZnO/CeO₂ NRs exhibited a higher concentration of Ce³⁺ species and were deficient in oxygen/adsorbed oxygen species. The results of the catalytic tests indicated enhanced activity for ZnO/CeO₂ NRs in comparison to pure CeO₂ NRs. More surface oxygen vacancies with a higher concentration of Ce³⁺ species, and low-temperature reducibility due to the interaction of ZnO and CeO₂, were found to contribute to the observed excellent catalytic activity and stability (up to 45 h) of ZnO/CeO₂ NRs in the CO oxidation.