Synthesis of Pd‐Rh Core–Frame Concave Nanocubes and Their Conversion to Rh Cubic Nanoframes by Selective Etching of the Pd Cores

Xie, Shuifen; Lü, Ning; Xie, Zhaoxiong; Wang, Jinguo; Kim, Moon J.; Xia, Younan

doi:10.1002/ange.201206044

Cited by 61 publications

(50 citation statements)

References 49 publications

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“…However,i nt he presence of aP d(100)specific capping agent such as Br À ions,the surface energy of Pd(100) can decrease to alevel so that g Pd(100) becomes lower than g Pd (111) . [68] In addition to binding strength, the degree of coverage also has agreat impact on the growth pattern. [68] In addition to binding strength, the degree of coverage also has agreat impact on the growth pattern.…”

Section: The Influence Of Capping Agentsmentioning

confidence: 99%

Seed‐Mediated Growth of Colloidal Metal Nanocrystals

et al. 2016

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Seed-mediated growth is a powerful and versatile approach for the synthesis of colloidal metal nanocrystals. The vast allure of this approach mainly stems from the staggering degree of control one can achieve over the size, shape, composition, and structure of nanocrystals. These parameters not only control the properties of nanocrystals but also determine their relevance to, and performance in, various applications. The ingenuity and artistry inherent to seed-mediated growth offer extensive promise, enhancing a number of existing applications and opening the door to new developments. This Review demonstrates how the diversity of metal nanocrystals can be expanded with endless opportunities by using seeds with well-defined and controllable internal structures in conjunction with a proper combination of capping agent and reduction kinetics. New capabilities and future directions are also highlighted.

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Section: The Influence Of Capping Agentsmentioning

confidence: 99%

Seed‐Mediated Growth of Colloidal Metal Nanocrystals

et al. 2016

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“…In the following discussion, we refer to them as "Pd cubic seeds" for simplicity. We chose them as seeds for two major reasons: (i) they had a well-defined shape, together with a set of low-index facets on the surface (8,9); and (ii) their side faces are blocked by Br -ions to ensure selective deposition of atoms onto the corner sites during seed-mediated growth (10)(11)(12). These two distinctive features allowed us to easily track the deposition of atoms and their surface diffusion during a growth process by analyzing the shape or morphology of the final product.…”

mentioning

confidence: 99%

On the role of surface diffusion in determining the shape or morphology of noble-metal nanocrystals

Xia

Xie

Liu

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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359

457

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Controlling the shape or morphology of metal nanocrystals is central to the realization of their many applications in catalysis, plasmonics, and electronics. In one of the approaches, the metal nanocrystals are grown from seeds of certain crystallinity through the addition of atomic species. In this case, manipulating the rates at which the atomic species are added onto different crystallographic planes of a seed has been actively explored to control the growth pattern of a seed and thereby the shape or morphology taken by the final product. Upon deposition, however, the adsorbed atoms (adatoms) may not stay at the same sites where the depositions occur. Instead, they can migrate to other sites on the seed owing to the involvement of surface diffusion, and this could lead to unexpected deviations from a desired growth pathway. Herein, we demonstrated that the growth pathway of a seed is indeed determined by the ratio between the rates for atom deposition and surface diffusion. Our result suggests that surface diffusion needs to be taken into account when controlling the shape or morphology of metal nanocrystals. seeded growth | shape control | noble metals S urface diffusion is a general process that involves the motion of adsorbed atoms (adatoms), molecules, or atomic clusters on the surface of a solid material (1, 2). Over the past decades, it has emerged as an important concept in many areas of surface science, including catalysis, epitaxial growth, and electromigration of voids (3-7). Here, we demonstrated that surface diffusion also plays a pivotal role in determining the growth pathway of a seed and thus the shape or morphology taken by the final product in a solutionphase synthesis of metal nanocrystals. Fig. 1 schematically illustrates four possible pathways for the growth of a cubic seed. As a model system, we focused on Pd nanocubes with slight truncation at corners and edges, together with six side faces passivated by chemisorbed Br -ions. In the following discussion, we refer to them as "Pd cubic seeds" for simplicity. We chose them as seeds for two major reasons: (i) they had a well-defined shape, together with a set of low-index facets on the surface (8, 9); and (ii) their side faces are blocked by Br -ions to ensure selective deposition of atoms onto the corner sites during seed-mediated growth (10-12). These two distinctive features allowed us to easily track the deposition of atoms and their surface diffusion during a growth process by analyzing the shape or morphology of the final product.The newly formed Pd atoms resulting from the reduction of a Pd precursor are expected to deposit at the corners of a cubic seed because the side faces are blocked by the chemisorbed Br -ions (Fig. 1A, 1). Upon deposition, there will be two different options for these adatoms: staying at the corner sites or migrating to other sites, including edges and side faces, through surface diffusion (Fig. 1A, 2 and 3). It should be pointed out that only surface diffusion was allowed here to move atoms from corners to edg...

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“…The core-frame structure allows for the exhibition of both materials on the surface of a catalyst. Using Pd nanocubes as a template, we demonstrated the synthesis of Pd-Rh bimetallic nanocubes with a core-frame structure and concave side faces through site-specific nucleation and growth of Rh at the corners and edges only (43). The key is the selective chemisorption of Br − ions on the {100} facets of a Pd cubic seed, which would block the deposition of the newly formed Rh atoms, and the involvement of a proper deposition rate for the Rh atoms.…”

Section: Core-frame Structurementioning

confidence: 97%

“…Alternatively, Ag octahedra, enclosed by {111} facets, will be obtained when sodium citrate or citric acid is used as a capping agent, owing to their selective affinity toward Ag{111} facets (42). Significantly, a capping agent can also be used to block certain regions on the surface of a seed, forcing the newly formed atoms to nucleate and grow from the bare facets only (43). This approach can be used to create bimetallic nanocrystals with a precise control over the spatial distribution of atoms deposited during the growth process, which may prove useful in generating a tandem catalyst to work with a set of reactions simultaneously, together with enhanced thermal stability.…”

Section: Shape-controlled Synthesis Of Metal Nanocrystalsmentioning

confidence: 99%

Shape-Controlled Metal Nanocrystals for Heterogeneous Catalysis

Ruditskiy

Peng

Xia

2016

Annu. Rev. Chem. Biomol. Eng.

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The ability to control the shape of metal nanocrystals allows us to not only maneuver their physicochemical properties but also optimize their activity in a variety of applications. Heterogeneous catalysis, in particular, would benefit tremendously from the availability of metal nanocrystals with controlled shapes and well-defined facets or surface structures. The immediate benefits may include significant enhancements in catalytic activity and/or selectivity along with reductions in the materials cost. We provide a brief account of recent progress in the development of metal nanocrystals with controlled shapes and thereby enhanced catalytic performance for several reactions, including formic acid oxidation, oxygen reduction, and hydrogenation. In addition to monometallic nanocrystals, we also cover a bimetallic system, in which the two metals are formulated as alloyed, core-shell, or core-frame structures. We hope this article will provide further impetus for the development of next-generation heterogeneous catalysts essential to a broad range of applications.

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Synthesis of Pd‐Rh Core–Frame Concave Nanocubes and Their Conversion to Rh Cubic Nanoframes by Selective Etching of the Pd Cores

Cited by 61 publications

References 49 publications

Seed‐Mediated Growth of Colloidal Metal Nanocrystals

Seed‐Mediated Growth of Colloidal Metal Nanocrystals

On the role of surface diffusion in determining the shape or morphology of noble-metal nanocrystals

Shape-Controlled Metal Nanocrystals for Heterogeneous Catalysis

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