Tuning Branching in Ceria Nanocrystals

Abstract

Branched nanocrystals (NCs) enable high atomic surface exposure within a crystalline network that provides optimized transport properties. Herein we report on the colloidal synthesis of branched ceria NCs by means of a ligand-mediated overgrowth mechanism. In particular, the differential coverage of oleic acid as X-type ligand at ceria facet with different atomic density, atomic coordination deficiency and oxygen vacancy density, results in a preferential growth in the [111] direction and thus in the formation of ceria octapods. Alcohols, through and esterification alcoholysis reaction, promote faster growth rates that translate into nanostructures with higher geometrical complexity, increasing the branch aspect ratio and triggering the formation of side branches. The presence of water on the other hand resulted in a significant reduction of the growth rate, decreasing the reaction yield and eliminating side branching, which we associate to a displacement of the alcoholysis reaction. Overall, adjusting the amounts of each chemical, well-defined branched ceria NCs with tuned number, thickness and length of the branches and with overall size ranging from 5 to 45 nm could be produced. We further demonstrate such branched ceria NCs to provide higher surface areas and related oxygen storage capacities (OSC) than quasi-spherical NCs obtained in the presence of only oleylamine.

Tin Selenide Molecular Precursor for the Solution Processing of Thermoelectric Materials and Devices

“…At relatively high OAc concentrations, OAc/OAm>0.2, dendritic structures were produced, which we associate with a selective binding of the carboxylic group in OAc to particular facets during crystal growth. [44][45] Through AFM analysis, the thickness of plates and dendritic structures supported on a substrate was measured to be in the range 100-150 nm, which is slightly larger than values obtained from SEM statistics (Figure 3e)…”

Metal Oxide Aerogels with Controlled Crystallinity and Faceting from the Epoxide-Driven Cross-Linking of Colloidal Nanocrystals

“…Quasi-spherical ceria NCs with an average size of 7  1 nm were produced following our previously reported procedure. 35 In brief, NCs were obtained through the decomposition at 300 °C of cerium nitrate hexahydrate in an ODE solution containing OAm (Figure 1a). The presence of OAm at the surface of the ceria NCs limited their growth and rendered them soluble in non-polar organic solvents.…”

“…The gelation approach here proposed was also used to produce NC-based ceria aerogels employing NCs with other sizes and geometries, and particularly hyperbranched ceria NCs ( Figure 7). 35 Hyperbranched ceria NCs were characterized by an intrinsic porous structure that provides them with specific surface areas up to 157 m 2 /g. 35 As for spherical ceria NCs, the surface of ceria hyperbranched NCs was in a first step functionalized with Gln to render the NCs soluble in polar solvents.…”

“…Ceria NCs were synthesized though the thermal decomposition of cerium(III) nitrate within ODE in the presence of OAm, according to a procedure we previously reported. 35 Briefly, 0.434 g (1 mmol) of cerium(III) nitrate hexahydrate were mixed with 2 mL (6 mmol) of OAm in 4 mL of ODE in a 25 mL three neck flask and under magnetic stirring. After degassing the mixture for 30 minutes at 80 °C, the obtained brown colour solution was heated under argon flow up to 300 °C at a rate of 15 °C/min.…”

You Talking to Me? Cadherin and Integrin Crosstalk in Biomaterial Design

“…All of these AJ reinforcements, together with actomyosin remodeling, provide cells with the necessary information to regulate embryo morphogenesis, [ 57 ] barrier maintenance, [ 48 ] proliferative control in adult tissue, or collective migration. [ 58 ] Also, mechanical forces that are sensed via the cell–cell junctions provide a mode of cell–cell communication that complements better understood modes of communication such as gap junctions or secreted factors.…”