Cation Dopants in Ceria: A Perspective on Current Research and a Case Study Using CeO₂ Aerogels

Substitutional or interstitial metal-cation dopants in CeO₂ play key roles in catalytic, sensing, and energy applications. Cation dopants with a valency less than 4+ create charge-compensating oxygen vacancies in the lattice that boost ionic conductivity and act as reactant adsorption/dissociation sites. These cation dopants also modify the optical properties of CeO₂, enabling the normally high-bandgap oxide to more effectively harvest visible light. In this perspective, we highlight the key progress made using dopants in CeO₂ and the challenges that remain. We briefly summarize common roles that cation dopants play in the CeO₂ lattice, including how their speciation and solubility affect materials properties. We also report how the structural and optical properties of CeO₂ aerogels vary when doped with transition metals (Co, Ni) or lanthanides (Y, La, Gd, Tb, Ho, and Er), thereby providing a rare look at the effects of a diverse group of dopants on a single morphologically fixed system.