Morphological Phase Diagram of Biocatalytically Active Ceria Nanostructures as a Function of Processing Variables and Their Properties

Abstract

We rationalize how fluorite‐structured CeO2, which is crystallographically isotropic, can grow anisotropically (without templates) to form nanoparticles, rods, and cubes. In particular, single‐crystalline and monodispersed cubic CeO2 nanoparticles, nanorods, and nanocubes have been selectively synthesized by a very simple, efficient, and economical hydrothermal process using different NaOH concentrations, and Ce(NO3)3 as the cerium precursor. High‐resolution transmission electron microscopy reveals nanomaterials with differently exposed crystal planes: {111} and {100} for nanoparticles, {110} and {100} for nanorods, and {100} for nanocubes. During the preparation of the CeO2 nanomaterials, the formation of intermediate anisotropic Ce(OH)3 species under basic conditions and their conversion into CeO2 at higher temperature are key factors responsible for the shape evolution. Atomistic computer simulations were used to help rationalize how the synthetic conditions impact upon the morphology of the nanomaterial. The synthesized CeO2 nanoparticles and nanorods demonstrate higher catalase mimetic activities than the nanocubes.

In-situ observation of radiation physics and chemistry of nanostructured cerium oxide in water

“…Ceria nanoparticulate powders are sampled from pre-manufactured nanoparticle dispersions for liquid cell TEM observation, followed by specific in-situ electron irradiation procedures. Particles are either 10-40 nm size commercial ceria nanoparticles (CeO 2 , purity >99.9%), characterised earlier [32], or ceria nanorods fabricated as described earlier [33,34]. Ceria nano-particles are suspended in DI water to be placed into the liquid cell (model Protochips Poseidon P500 [35]) comprising a microfluidic cell of two Si 3 N 4 membranes.…”

“…Due to the complex dissolution found for CNPs of various roundness, it is of interest to compare nanoparticles with ceria nanorods (CNRs) as dissolution targets, see Figure 3. CNRs are suggested to result from needle-shape hydroxide nucleation events during ex-situ synthesis before transforming to ceria during hydrothermal ageing [33,34]. With the cylindrical symmetry pre-existing, volume losses can be quantified easily from a suitably chosen cylindrical segment.…”

Morphology and Crystal Planes Effects on Supercapacitance of CeO2 Nanostructures: Electrochemical and Molecular Dynamics Studies

“…Synthesis Procedure : The procedure to selectively synthesize different morphologies, CNPs, CNRs, and CNCs, used a template‐free hydrothermal process by varying the caustic condition, time, and temperature of the reaction. The details of which can be found in Sakthivel et al Briefly, appropriate amounts of Ce(NO 3 ) 3 .6H 2 O and NaOH were separately mixed to 20 mL of deionized water (DI H 2 O). The two solutions were then mixed together with vigorous stirring.…”

“…Recently, we reported the shape‐controlled synthesis of different CeO 2 nanostructures by a one‐step hydrothermal synthesis method and also established a morphological phase diagram for the same . However, the relationship between the morphology of nanostructured CeO 2 and crystal plane effect on charge storage capacity has not yet been reported.…”

The Change in Antioxidant Properties of Dextran‐Coated Redox Active Nanoparticles Due to Synergetic Photoreduction–Oxidation

“…On the other hand, in the case of Dex-CNPs exposed to light, the agglomeration indicated by noticeable overlapping of nanoparticles on exposure to light can be evidently observed, without compromisingt he crystallinity,s hapea nd size of nanoparticles. Cerium oxide has af luo-rite structure with signature peaks corresponding to the planes( 111), (200), (220), (311), (222), (400) and (331) (JCPDS 34-0394) [13] as showni nF igure 2B.T he XRD spectrum of Dex-CNPs kept in the dark and Dex-CNPs exposed to light indicates that the peaks corresponding to (111), (200), (220)a nd (311) planeso ft he CNPs fluorite structure [14] were retained when coated with dextrana nd the exposure to the light did not diminish the crystallinity or the intrinsic structure of the CNPs. The broadening of the peak in case of Dex-CNPs may be due to the smaller size of CNPs.…”