Abstract
Rare earth metal oxides (REMOs) have gained considerable attention in recent years owing to their distinctive properties and potential applications in electronic devices and catalysts. Particularly, cerium dioxide (CeO2), also known as ceria, has emerged as an interesting material in a wide variety of industrial, technological, and medical applications. Ceria can be synthesized with various morphologies, including rods, cubes, wires, tubes, and spheres. This comprehensive review offers valuable perceptions into the crystal structure, fundamental properties, and reaction mechanisms that govern the well-established surface-assisted reactions over ceria. The activity, selectivity, and stability of ceria, either as a stand-alone catalyst or as supports for other metals, are frequently ascribed to its strong interactions with the adsorbates and its facile redox cycle. Doping of ceria with transition metals is a common strategy to modify the characteristics and to fine-tune its reactive properties. DFT-derived chemical mechanisms are surveyed and presented in light of pertinent experimental findings. Finally, the effect of surface termination on catalysis by ceria is also highlighted.
Highlights
Rare earth (RE) elements have gained considerable interest due to the distinguished electronic configuration triggered by their 4f electrons
It is worth mentioning that from an atomistic point of view, numerous density functional theory (DFT)-based studies with various functionals such as the HSE06 (Heyd– Scuseria–Ernzerhof hybrid functional) and the DFT+U approach (U corresponds to Hubbard parameter describing the on-site Coulomb interactions) have been reported
This use is supported by high bandgap energy, high refractive index [178], high optical transparency in the visible region [179], and excellent oxygen storage capacity resulting from the easy conversion of cerium ions between reduced and oxidized states (Ce3+–Ce4+) through fast creation and removal of oxygen vacancies in CeO2
Summary
Rare earth (RE) elements have gained considerable interest due to the distinguished electronic configuration triggered by their 4f electrons They differ from other elements in that their valance electrons can occupy more than one shell, offering them several possible oxidation states. Along the same line of inquiry, the valence of cerium displays a significant influence on the structure of cerium dioxides in that tetravalent Ce comprises cerium dioxide (CeO2) that exhibits a cubic fluorite lattice (Fm3m space group) and the oxygen anions occupy the eight tetrahedral 8c sites, whereas trivalent cerium displays the sesquioxide Ce2O3. The latter displays a hexagonal lattice (P3m1 space group). It is revealed that the oxides of rare earth metals, mainly Ce, La, and Y, could enhance the high-temperature orxairdeaetaiortnhrmeseisttaalns,cemoafinvlayriCoue,sLmae, taanldalYlo,ycsoupldtoen1h0a0n0c°eCth[8e].high-temperature oxidation resistance of various metal alloys up to 1000 ◦C [8]
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