CeO2

CeO2, or cerium(IV) oxide, commonly called ceria, is a pale yellow-white solid oxide of cerium. It adopts the fluorite-type lattice and is the most stable oxide form of cerium. The material readily undergoes reduction from Ce4+ to Ce3+, creating oxygen vacancies in the lattice that enable rapid oxygen exchange. This redox flexibility gives ceria a high oxygen storage capacity and makes it useful in redox catalysis and sensing.

Structure and properties

Ceria has a cubic fluorite structure with Ce4+ ions in a face-centered cubic array and oxide ions occupying the tetrahedral sites. The lattice accommodates nonstoichiometry CeO2−x, where x reflects the amount of oxygen vacancy formation under reducing conditions. The Ce4+/Ce3+ couple drives catalytic activity and oxygen buffering. Doping ceria with aliovalent cations (for example Gd3+, Sm3+) enhances ionic conductivity, enabling its use as an electrolyte in intermediate-temperature solid oxide fuel cells.

Synthesis and forms

Commercial ceria is produced as fine powders and can be synthesized by precipitation, hydrothermal methods, sol–gel processes, or combustion techniques. It forms stable powders, nanomaterials, and supported catalysts. Doped ceria materials (CeO2 doped with trivalent metals) are common for electrochemical and fuel-cell applications.

Applications

Ceria is used as a catalyst and catalyst support in automotive exhaust systems, in oxidation and reforming reactions, and as an oxygen storage component. It serves in gas and chemical sensors and in polishing slurries for glass and optics. In energy devices, doped ceria-based electrolytes enable IT-SOFCs due to higher ionic conductivity at intermediate temperatures.

Safety and handling

Ceria particles are generally considered low toxicity, but inhalation of fine dust should be avoided. Standard laboratory and industrial hygiene practices apply.

See also: cerium, doped ceria, fluorite structure.