Cerium valence state conversion: Fabrication and environmental remediation of modified CeO2 mater ials

Rare earth elements are highly applicable in photocatalysis due to their partially filled 4f orbitals, existing in electronic structures that facilitate the transfer of electrons during the reaction process. Among these materials, CeO2 has a distinctive external electronic structure (4f15d16s2), abundant oxygen vacancies, and strong conversion ability of Ce4+/Ce3+, which makes it an attractive candidate in the field of photocatalysis. To broaden its practical applications in the visible region, the drawbacks of a wide band gap and a slow Ce4+/Ce3+ cycle have been addressed through the modification of CeO2, thereby accelerating light absorption and self-circulation, and enhancing photocatalytic activity. This paper presents a review of the preparation of modified CeO2 catalysts and their application in the conversion of cerium valence state in the photocatalytic degradation of pollutants in water. Furthermore, this paper presents a summary of the most recent development and current challenges, as well as prospect for the application of modified CeO2-based materials. (c) 2025 Published by Elsevier B.V. on behalf of Chinese Society of Rare Earths.