PNNL

Abstract

Nanoparticles of ceria have numerous practical applications in catalysis and fuel cells, as gas sensors and as therapeutics for numerous biomedical treatments. In all cases, the selectivity of the desired application is driven by uniformity in the size and chemical composition of the nanoparticles. Here we report radiation-induced preparation of homogeneously distributed Ce(III) nanostructures in an in-situ liquid cell for the transmission electron microscope (TEM). The chemical environment necessary to promote uniform growth is achieved through high electron beam currents on aqueous solutions containing cerium ions. Compared to previous radiolytic synthesis routes in aqueous solution for other metal or metal oxide nanoparticles, the chemical pathways leading to Ce(III) nanostructures require an increase in the local pH. This is achieved here by a set of catalytic reactions that are driven by the intrinsic instability of Ce0 in aqueous solutions. These results indicate that a wide range of chemical conditions can be induced by radiolysis and used to synthesize oxidized nanostructures from solution.