PNNL

Abstract

To obtain greater molecular and structural understanding of chemical state transformations previously reported for ceria ˜ 3 nm nanoparticles (CNPs) in response to changing solution conditions, microXRD and Raman measurements were made for various solution conditions. The particles were observed to undergo a reversible transformation from a defected ceria structure to a non-ceria amorphous oxy-hydroxide phase in response to the addition of 30% hydrogen peroxide. For CNPs made up of 8 nm crystallites, a partial transformation was observed and no transformation was observed for CNPs made up of ˜ 40 nm crystallites. These observations of differences in size dependent transition behavior may help explain the benefits of smaller CNPs size on the regenerative behaviors and the frequently reported importance of surface ligands on CNP transformations.