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.