In situ formation of 1D nanostructures from ceria nanoparticle dispersions by liquid cell TEM irradiation

Abstract

Deliberate electron irradiation of cerium oxide nanoparticles in water is used to trigger chemical reactions in a liquid cell transmission electron microscope. Formation of nanorods and nanoneedles is observed starting from predominantly octahedral shape nanoparticles. Detailed morphologies found include free-standing needles, needles connected to specific octahedral ceria facets and star-shaped multi-needle patterns. It is found that rod-axis orientations and crystallographic directions are aligned. It is suggested that high ion and radical concentration of radiolysed water dissolves layers of the original CeO 2 particles which rearrange as needles in the direction of energetically preferred facets.

Design strategies for ceria nanomaterials: untangling key mechanistic concepts

“…132,133 The low stability and presence of the dipole for the former of these two oxygen-terminated (and hence negatively charged) planes [134][135][136][137] explain the preferential adsorption of the anionic ligand on the {100} planes; this epitaxial attachment has been observed before. 138 So face-toface adsorption occurs by the preceding processes but with annihilation of {100} planes, resulting in a zigzag nanostructure, which is required for h110i growth directions. The surface area decreases through growth of the outer {111} and remaining {100} planes, followed by coalescence and Ostwald ripening to establish a single crystal with a hexagonal prism consisting of a {111} rhombic prism and one {100} pinacoid, again with h110i growth directions.…”

Radiation Chemistry Provides Nanoscopic Insights into the Role of Intermediate Phases in CeO2 Mesocrystal Formation

“…At the same time, the diameters of the primary particles remain unchanged even at such high doses (≈3 nm). Further growth may happen due to the aggregation of the mesocrystals [46] …”

“…Further growth may happen due to the aggregation of the mesocrystals. [46] To deepen our understanding of the early events of the process,weanalyzed the electron radial distribution functions obtained from zero-loss energy filtered electron diffraction patterns (EF-eRDF). Figure 4(b) shows the evolution of the EF-eRDFs with respect to the absorbed dose.T he signal starts to differ from that of the pure carbon support at doses !…”