An official website of the United States government
The aspect ratio-dependent properties of gold nanorods are used in a variety of applications, but the cause of anisotropic nanorod growth remains unclear. Measurements utilizing single-crystal electrodes were collected to determine what additive(s) in pentatwinned gold nanorod syntheses are responsible for facet-selective atomic addition. With cetyltrimethylammonium in the absence of bromide, the rate of atomic addition to Au(100) and Au(111) single crystals was the same, and isotropic nanoparticles were produced. The addition of increasing concentrations of bromide suppressed the rate of atomic addition to Au(100) relative to Au(111) and increased the aspect ratio of gold nanorods. Bromide was a more effective passivator of Au(100) in the absence of cetyltrimethylammonium, indicating cetyltrimethylammonium does not cause facet-selective atomic addition. Cetyltrimethylammonium surfactant is still necessary for gold nanorod growth because it reduces the rate of gold ion reduction and stabilizes suspended nanoparticles against aggregation.
more »
« less
This content will become publicly available on September 9, 2026
Molten salt synthesis of increased (100)-facet and polycrystalline nickel oxide nanoparticles for the oxygen evolution reaction: impact of facet and crystallinity on electrocatalysis
Nickel oxide nanocubes with increased (100) surface facet presence (NiO(100)) were synthesized through a molten salt synthesis procedure in order to investigate the relationship between the surface facet and OER performance.
more »
« less
- Award ID(s):
- 2139971
- PAR ID:
- 10637895
- Publisher / Repository:
- Royal Society of Chemistry
- Date Published:
- Journal Name:
- RSC Applied Interfaces
- Volume:
- 2
- Issue:
- 5
- ISSN:
- 2755-3701
- Page Range / eLocation ID:
- 1448 to 1460
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
ABSTRACT We report a facile method to fabricate CuNi nano-octahedra and nanocubes using a colloidal synthesis approach. The CuNi nanocrystals terminated with exclusive crystallographic facets were controlled and achieved by a group of synergetic capping ligands in a hot solution system. Specifically, the growth of {111}-bounded CuNi nano-octahedra is derived by a thermodynamic control, whereas the generation of {100}-terminated CuNi nanocubes is steered by a kinetic capping of chloride. Using a reduction of 4-nitrophenol with sodium borohydride as a model reaction, CuNi nano-octahedra and nanocubes demonstrated a strong facet-dependence due to their different surface energies although both exhibited remarkable catalytic activity with the high rate constant over mass (k/m). A kinetic study indicated that this is a pseudo first-order reaction with an excess of sodium borohydride. CuNi nanocubes as the catalysts showed better catalytic performance (k/m = 385 s -1 •g -1 ) than the CuNi nano-octahedra (k/m = 120 s -1 •g -1 ), indicating that 4-nitrophenol and hydrogen were adsorbed on the {100} facets with their molecules parallel to the surface much easier than those on {111} facets.more » « less
-
Abstract Oxide supports with well‐defined shapes enable investigations on the effects of surface structure on metal–support interactions and correlations to catalytic activity and selectivity. Here, a modified atomic layer deposition technique was developed to achieve ultra‐low loadings (8–16 ppm) of Pt on shaped ceria nanocrystals. Using octahedra and cubes, which expose exclusively (111) and (100) surfaces, respectively, the effect of CeO2surface facet on Pt‐CeO2interactions under reducing conditions was revealed. Strong electronic interactions result in electron‐deficient Pt species on CeO2(111) after reduction, which increased the stability of the atomically dispersed Pt. This afforded significantly higher NMR signal enhancement in parahydrogen‐induced polarization experiments compared with the electron‐rich platinum on CeO2(100), and a factor of two higher pairwise selectivity (6.1 %) in the hydrogenation of propene than any previously reported monometallic heterogeneous Pt catalyst.more » « less
-
Abstract Facet‐selective etching and deposition, as determined by the landscape of surface energy, represent two powerful methods for the transformation of noble‐metal nanocrystals into nanostructures with complex shapes or morphologies. This review highlights the use of these two methods, including integration of them, for the fabrication of novel monometallic and bimetallic nanostructures with enhanced properties. We start with an introduction to the role of surface capping in controlling the facet‐selective etching or deposition on the surface of Ag nanocrystals, followed by a case study of how to maneuver etching and deposition at different facets of Pd nanocrystals for the fabrication of nanoframes. We then introduce the use of galvanic replacement to accomplish selective etching and deposition on two different facets in an orthogonal manner, transforming Pd nanocubes into Pd−Pt octapods. By complementing galvanic replacement with a chemical reduction reaction, it is also feasible to control the rates of these two reactions for the conversion of Ag nanocubes into Ag@Ag−Au concave nanocubes and Ag@Au core‐shell nanocubes. These transformation methods not only greatly increase the shape diversity of metal nanocrystals but also offer nanocrystals with enhanced plasmonic and/or catalytic properties.more » « less
-
Faceted interfaces are omnipresent on the web to support data exploration and filtering. A facet is a triple: a domain (e.g., Book), a property (e.g., author, language), and a set of property values (e.g., Austen, Beauvoir, Coelho, Dostoevsky, Eco, Kerouac, Suskind, ..., French, English, German, Italian, Portuguese, Russian, ... ). Given a property (e.g., language), selecting one or more of its values (English and Italian) returns the domain entities (of type Book) that match the given values (the books that are written in English or Italian). To implement faceted interfaces in a way that is scalable to very large datasets, it is necessary to automate facet extraction. Prior work associates a facet domain with a set of homogeneous values, but does not annotate the facet property. In this paper, we annotate the facet property with a predicate from a reference Knowledge Base (KB) so as to maximize the semantic similarity between the property and the predicate. We define semantic similarity in terms of three new metrics: specificity, coverage, and frequency. Our experimental evaluation uses the DBpedia and YAGO KBs and shows that for the facet annotation problem, we obtain better results than a state-of-the-art approach for the annotation of web tables as modified to annotate a set of values.more » « less
