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Journal ArticleDOI

Bimetallic nanoparticles—novel materials for chemical and physical applications

01 Jan 1998-New Journal of Chemistry (The Royal Society of Chemistry)-Vol. 22, Iss: 11, pp 1179-1201
TL;DR: In this article, a review on the preparation, characterization and application of polymer- or ligand-stabilized bimetallic nanoparticles in dispersion, emphasizing their own work and introducing recent progress of this area is presented.
Abstract: A new class of materials for catalysis have been intensively investigated, that is, ‘bimetallic nanoparticles’. Extensive studies of non-supported bimetallic nanoparticle dispersions, stabilized by polymers or ligands, started only about 10 years ago. Many preparative procedures have been proposed, and detailed characterizations have been carried out on bimetallic nanoparticles, thanks to the rapid improvement of analytical technology on surface and nanoscale materials. In this review, we focus on the preparation, characterization and application to catalysis of polymer- or ligand-stabilized bimetallic nanoparticles in dispersion, emphasizing our own work and introducing recent progress of this area.

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TL;DR: A review of gold nanoparticles can be found in this article, where the most stable metal nanoparticles, called gold colloids (AuNPs), have been used for catalysis and biology applications.
Abstract: Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

11,752 citations

Journal ArticleDOI
TL;DR: Nanoalloys of Group 11 (Cu, Ag, Au) 865 5.1.5.2.
Abstract: 5.1. Nanoalloys of Group 11 (Cu, Ag, Au) 865 5.1.1. Cu−Ag 866 5.1.2. Cu−Au 867 5.1.3. Ag−Au 870 5.1.4. Cu−Ag−Au 872 5.2. Nanoalloys of Group 10 (Ni, Pd, Pt) 872 5.2.1. Ni−Pd 872 * To whom correspondence should be addressed. Phone: +39010 3536214. Fax:+39010 311066. E-mail: ferrando@fisica.unige.it. † Universita di Genova. ‡ Argonne National Laboratory. § University of Birmingham. | As of October 1, 2007, Chemical Sciences and Engineering Division. Volume 108, Number 3

3,114 citations

Journal ArticleDOI
TL;DR: The Review presents the recent developments and the use of NP catalysis in organic synthesis, for example, in hydrogenation and C--C coupling reactions, and the heterogeneous oxidation of CO on gold NPs.
Abstract: Interest in catalysis by metal nanoparticles (NPs) is increasing dramatically, as reflected by the large number of publications in the last five years. This field, "semi-heterogeneous catalysis", is at the frontier between homogeneous and heterogeneous catalysis, and progress has been made in the efficiency and selectivity of reactions and recovery and recyclability of the catalytic materials. Usually NP catalysts are prepared from a metal salt, a reducing agent, and a stabilizer and are supported on an oxide, charcoal, or a zeolite. Besides the polymers and oxides that used to be employed as standard, innovative stabilizers, media, and supports have appeared, such as dendrimers, specific ligands, ionic liquids, surfactants, membranes, carbon nanotubes, and a variety of oxides. Ligand-free procedures have provided remarkable results with extremely low metal loading. The Review presents the recent developments and the use of NP catalysis in organic synthesis, for example, in hydrogenation and C--C coupling reactions, and the heterogeneous oxidation of CO on gold NPs.

2,790 citations

Journal ArticleDOI
TL;DR: This work has shown that coherent oscillations of conduction electrons on a metal surface excited by electromagnetic radiation at a metal -dielectric interface can be associated with surface plasmons, which have potential applications in miniaturized optical devices, sensors, and photonic circuits.
Abstract: Surface plasmons (SPs) are coherent oscillations of conduction electrons on a metal surface excited by electromagnetic radiation at a metal -dielectric interface. The growing field of research on such light -metal interactions is known as ‘plasmonics’. 1-3 This branch of research has attracted much attention due to its potential applications in miniaturized optical devices, sensors, and photonic circuits as well as in medical diagnostics and therapeutics. 4-8

2,284 citations

Journal ArticleDOI
TL;DR: In this article, a photoactive molecule (e.g., pyrene) is added to a metal nanoparticle to enhance the photochemical activity and render the organic−inorganic hybrid nanoassemblies suitable for light harvesting and optoelectronic applications.
Abstract: Unique electronic and chemical properties of metal nanoparticles have drawn the attention of chemists, physicists, biologists, and engineers who wish to use them for the development of new generation nanodevices. Metal nanoparticles such as gold and silver show noticeable photoactivity under UV−visible irradiation as is evident from the photoinduced fusion and fragmentation processes. Binding a photoactive molecule (e.g., pyrene) to metal nanoparticle enhances the photochemical activity and renders the organic−inorganic hybrid nanoassemblies suitable for light-harvesting and optoelectronic applications. The nature of charge-transfer interaction of fluorophore with gold surface dictates the pathways with which the excited-state deactivates. Obtaining insight into energy and electron-transfer processes is important to improve the charge separation efficiencies in metal−fluorophore nanoassemblies and photocatalytic activity of metal−semiconductor composites.

1,870 citations

References
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Journal ArticleDOI
TL;DR: In this paper, a preliminary survey with the electron microscope of various preparations of colloidal gold, a study was made of the process of nucleation and growth in gold colloids, and it was shown that nucleating agents may be identified with reducing agents which form a mixed polymer with chlorauric ion before the reduction to the nucleus takes place.
Abstract: After a preliminary survey with the electron microscope of various preparations of colloidal gold, a study was made of the process of nucleation and growth in gold colloids. It was shown that nucleating agents may be identified with reducing agents which form a mixed polymer with chlorauric ion before the reduction to the nucleus takes place. It was also shown that the law of growth is exponential. The average size, the deviation from the average size and the character of the particle size distribution curve are determined by the amount of gold, the nucleation process and the law of growth.

6,593 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of surface modification on colloidal metal particles in aqueous solution were investigated. And the resulting changes in the chemical, photochemical, and optical properties were discussed.
Abstract: The study of nanometer and subnanometer colloidal metal particles in aqueous solution complements the investigation of small particles in molecular beams, frozen solutions, and inorganic clusters. The electronic properties of the metal particles are changed by surface modification, for example by chemisorption of a nucleophilic molecule or by deposition of a second metal. The resulting changes in the chemical, photochemical, and optical properties are discussed. Methods are described which enable one to store excess electrons or positive holes on the particles in a controlled manner and to investigate the accompanying changes in the optical properties. Metal particles carrying excess electrons initiate electrochemical reactions such as the reduction of water or the deposition of metals

1,633 citations

Journal ArticleDOI
TL;DR: In this article, a review of catalysis by metal clusters and colloids is presented, covering the period from 1980 to mid-1992, with a focus on the use of the terms colloid and cluster.
Abstract: This review covers catalysis by metal clusters and colloids. Any system that is a continuous phase is considered. Specifically not covered will be supported catalysts or heterogeneous catalysts except as they serve as comparative examples. Polymer-stabilized clusters and colloids are considered if they are soluble. The review will roughly cover the period from 1980 to mid-1992. Essential to this review is the establishment of definitions for the terms cluster and colloid. There are certain intuitive definitions for cluster and colloid. Recent work discussed below shows that the terms cluster and colloid are not clearly distinguishable. This review uses cluster and colloid interchangeably. However, several studies describe methods for distinguishing homogeneous from heterogeneous catalysts where heterogeneous catalysts may include colloids. For purposes of this review, a heterogeneous catalyst is defined as one where the catalyst is a separate phase, usually a filterable solid from a liquid phase. The distinction between mononuclear or low nuclearity clusters and large clusters or colloids does not necessarily distinguish homogeneous from heterogeneous catalysts. Methods for distinguishing whether a reaction is catalyzed by a mononuclear species or one where metal-metal bonds are present are described. The paper discusses the following: structure of large clusters and small colloids;more » onset to metallic properties; mononuclear vs. cluster catalysis; hydrogenation; CO activation; hydroformylation; H-H and C-H activation; hydrosilylation; isomerization; oligomerization; redox reactions; photocatalysis; water activation; oxidation; electrochemistry and electroless metal deposition; and ammonia synthesis and related nitrogen chemistry. 402 refs.« less

1,339 citations

BookDOI
24 Feb 1994

916 citations