Metallic nanocrystals synthesized in solution: a brief review of crystal shape theory and crystallographic characterization

Kappes, Branden B.; Leong, G. Jeremy; Gilmer, George H.; Richards, Ryan M.; Ciobanu, Cristian V.

doi:10.1002/crat.201500163

Cited by 5 publications

(7 citation statements)

References 74 publications

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“…The resulting Wulff shape is enclosed by the smallest set of surfaces capable of covering the entire volume. , Our unstrained Wulff shapes generally agree with those generated by the Crystallium database . We note that this approach does not account for growth or metastability kinetics, which can come into play especially at high temperatures and in the presence of surfactants . Size-dependent stress may also influence the morphology of nanoparticles …”

Section: Methodssupporting

confidence: 64%

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Theoretical Investigations of Transition Metal Surface Energies under Lattice Strain and CO Environment

2018

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An understanding of the relative stability of surface facets is crucial to develop predictive models of catalyst activity and to fabricate catalysts with a controlled morphology. In this work, we present a systematic density functional theory study of the effect of lattice strain and CO environment on the surface formation energies of Cu, Pt, and Ni. First, we show that both compressive and tensile lattice strains favor the formation of stepped versus low-index terraces such as (111) and (100). Then, we investigate the effect of the CO environment using configurations of CO at various coverages, determined using a greedy, systematic approach, inspired by forward stepwise feature selection. We find that the CO environment favors stepped facets on Ni, Cu, and Pt. These trends are illustrated with the corresponding equilibrium Wulff shapes at various strains and CO pressures. In general, the surface energies of the studied transition metals are highly sensitive to strain and CO coverage, which should be considered when rationalizing trends in the catalytic activity.

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Section: Methodssupporting

confidence: 64%

“…26 We note that this approach does not account for growth or metastability kinetics, which can come into play especially at high temperatures and in the presence of surfactants. 34 Sizedependent stress may also influence the morphology of nanoparticles. 35 2.5.…”

Section: Methodsmentioning

confidence: 99%

Theoretical Investigations of Transition Metal Surface Energies under Lattice Strain and CO Environment

2018

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“…S8 , see the Supplementary Information for detail explanation and Supplementary Results ). As the reaction temperature approaches the melting temperature of nanoparticles, the energy difference between facets decreases, creating spherical particles even with thermodynamically controlled growth 3 , 46 , 47 . In this study, we focus on the third regime, as spherical QDs are preferred in most optoelectronic applications with their superior optical and electronic properties.…”

Section: Resultsmentioning

confidence: 99%

Controllable modulation of precursor reactivity using chemical additives for systematic synthesis of high-quality quantum dots

et al. 2020

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The optical and electronic performance of quantum dots (QDs) are affected by their size distribution and structural quality. Although the synthetic strategies for size control are well established and widely applicable to various QD systems, the structural characteristics of QDs, such as morphology and crystallinity, are tuned mostly by trial and error in a material-specific manner. Here, we show that reaction temperature and precursor reactivity, the two parameters governing the surface-reaction kinetics during growth, govern the structural quality of QDs. For conventional precursors, their reactivity is determined by their chemical structure. Therefore, a variation of precursor reactivity requires the synthesis of different precursor molecules. As a result, existing precursor selections often have significant gaps in reactivity or require synthesis of precursor libraries comprising a large number of variants. We designed a sulfur precursor employing a boron-sulfur bond, which enables controllable modulation of their reactivity using commercially available Lewis bases. This precursor chemistry allows systematic optimization of the reaction temperature and precursor reactivity using a single precursor and grows high-quality QDs from cores of various sizes and materials. This work provides critical insights into the nanoparticle growth process and precursor designs, enabling the systematic preparation of high-quality QD of any sizes and materials.

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“…The MgO(111) facet contains oxygen defect sites and exposed oxygen anions and is stabilized by surface hydroxyl groups, resulting in a surface that is markedly different from its (100) or (110) counterparts. A metal oxide’s chemical properties, including catalytic activity, selectivity, and interactions (adsorption or binding) with atoms or molecules are directly correlated to its surface properties. , Specifically, for example, gold deposited on MgO(111) showed improved activity for the aerobic oxidation of benzyl alcohol relative to gold deposited on an MgO aerogel, with the difference attributed gold’s different interactions with the two supports …”

Section: Introductionmentioning

confidence: 99%

“…A metal oxide's chemical properties, including catalytic activity, selectivity, and interactions (adsorption or binding) with atoms or molecules are directly correlated to its surface properties. 23,24 Specifically, for example, gold deposited on MgO(111) showed improved activity for the aerobic oxidation of benzyl alcohol relative to gold deposited on an MgO aerogel, with the difference attributed gold's different interactions with the two supports. 25 Understanding of metal−support interactions is imperative for further optimization of materials such as catalysts.…”

Section: ■ Introductionmentioning

confidence: 99%

Iridium Atoms Bonded to Crystalline Powder MgO: Characterization by Imaging and Spectroscopy

et al. 2019

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Samples with low loadings of metals on well-defined supports provide some of the best opportunities to determine the metal–support structure and bonding. We illustrate methods for characterizing atomically dispersed heavy metals on metal oxide supports by aberration-corrected scanning transmission electron microscopy (STEM) complemented by fluorescence detection extended X-ray absorption fine structure and infrared spectroscopies. STEM images of Ir atoms derived from Ir(C2H4)2(acac) (acac = acetylacetonato) on high-surface-area MgO powder were obtained with minimized electron beam damage by quickly recording images near where the focus had been established. The images show that iridium at a loading of 1.0 wt % on MgO calcined at 1073 K was atomically dispersed, populating much of the surface of the MgO particles, which had irregular shapesconsequently the Ir atoms were bonded at various sites to two or three surface O atoms. In contrast, MgO calcined at 1273 K consisted of almost perfectly cubic crystals, and Ir atoms at a loading of only 0.01 wt % on this nearly ideal support were anchored preferentially at edges and corners of the (100) faces and bonded to three surface O atoms. The latter results indicate a path forward for the determination of precise structures of atomically dispersed metals on crystalline metal oxide supports.

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Metallic nanocrystals synthesized in solution: a brief review of crystal shape theory and crystallographic characterization

Cited by 5 publications

References 74 publications

Theoretical Investigations of Transition Metal Surface Energies under Lattice Strain and CO Environment

Theoretical Investigations of Transition Metal Surface Energies under Lattice Strain and CO Environment

Controllable modulation of precursor reactivity using chemical additives for systematic synthesis of high-quality quantum dots

Iridium Atoms Bonded to Crystalline Powder MgO: Characterization by Imaging and Spectroscopy

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