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

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

The interest in nanoscale materials stems from the fact that new properties are acquired at this length scale and, equally important, that these properties * To whom correspondence should be addressed. Phone, 404-8940292; fax, 404-894-0294; e-mail, mostafa.el-sayed@ chemistry.gatech.edu. † Case Western Reserve UniversitysMillis 2258. ‡ Phone, 216-368-5918; fax, 216-368-3006; e-mail, burda@case.edu. § Georgia Institute of Technology. 1025 Chem. Rev. 2005, 105, 1025−1102

Chemistry and properties of nanocrystals of different shapes.

This review focuses on the synthesis, protection, functionalization, and application of magnetic nanoparticles, as well as the magnetic properties of nanostructured systems. Substantial progress in the size and shape control of magnetic nanoparticles has been made by developing methods such as co-precipitation, thermal decomposition and/or reduction, micelle synthesis, and hydrothermal synthesis. A major challenge still is protection against corrosion, and therefore suitable protection strategies will be emphasized, for example, surfactant/polymer coating, silica coating and carbon coating of magnetic nanoparticles or embedding them in a matrix/support. Properly protected magnetic nanoparticles can be used as building blocks for the fabrication of various functional systems, and their application in catalysis and biotechnology will be briefly reviewed. Finally, some future trends and perspectives in these research areas will be outlined.

Magnetic nanoparticles: Synthesis, protection, functionalization, and application

Nanocrystals are fundamental to modern science and technology. Mastery over the shape of a nanocrystal enables control of its properties and enhancement of its usefulness for a given application. Our aim is to present a comprehensive review of current research activities that center on the shape-controlled synthesis of metal nanocrystals. We begin with a brief introduction to nucleation and growth within the context of metal nanocrystal synthesis, followed by a discussion of the possible shapes that a metal nanocrystal might take under different conditions. We then focus on a variety of experimental parameters that have been explored to manipulate the nucleation and growth of metal nanocrystals in solution-phase syntheses in an effort to generate specific shapes. We then elaborate on these approaches by selecting examples in which there is already reasonable understanding for the observed shape control or at least the protocols have proven to be reproducible and controllable. Finally, we highlight a number of applications that have been enabled and/or enhanced by the shape-controlled synthesis of metal nanocrystals. We conclude this article with personal perspectives on the directions toward which future research in this field might take.

Shape‐Controlled Synthesis of Metal Nanocrystals: Simple Chemistry Meets Complex Physics?

Core/Shell Nanoparticles: Classes, Properties, Synthesis Mechanisms, Characterization, and Applications

Preparation of aluminium doped zinc oxide particles by chemical vapor deposition

Vapor condensation on nanoparticle with radius smaller than the Kelvin radius is considered as fluctuation or as the heterogeneous nucleation. The expression for steady-state heterogeneous nucleation rate is obtained.

Heterogeneous Condensation on Nanoparticle

Submicron particles of Au-Ag (gold-silver) binary alloy were directly prepared using an ultrasonic spray pyrolysis (SP) method. A stable solution of Au(OH)3/HNO3 and AgNO3/HNO3 was prepared without hydrochloric acid. The particles prepared were spherical in shape and had prescribed composition ratio of Au-Ag. The applications of Au-Ag particles as electronic and ornamental materials were investigated by fabricating electrode pastes as well as paint for use in pottery. The electrode made by the present alloy particles had a higher heat resistance than those of mechanically mixed Au/Ag particles. The paint on the pottery plate derived from Au/Ag alloy particles was slightly-blue mat gold color.

https://www.jstage.jst.go.jp/article/sptj1978/41/4/41_4_246/_pdf

Preparation of Au/Ag Alloy Particles by Spray Pyrolysis and Its Applications

Two component metal oxide nanoparticles such as lithium cobalt oxides (LiCoO2), indium tin oxides (ITO) were synthesized from aqueous aerosol precursors by the flame spray pyrolysis. A high enough flame temperature was used for the complete thermal decomposition of the aerosol precursor. Molar concentration of the aqueous precursor solution, and the flow rate of combustion gas such as hydrogen are varied to control particle size, size distribution and crystal structure. Crystalline LiCoO2 and ITO nanoparticles with the average particle diameter ranging from 11 to 35 nm and from 11 to 20 nm were synthesized, respectively.

Kikuo Okuyama

Papers

Preparation of aluminium doped zinc oxide particles by chemical vapor deposition

Heterogeneous Condensation on Nanoparticle

Preparation of Au/Ag Alloy Particles by Spray Pyrolysis and Its Applications

Synthesis of binary component metal oxide nanoparticles by flame spray pyrolysis (第3回日韓資源リサイクル・材料科学に関する国際シンポジウム特集号)

Experimental Control of Preparation of Thin Film and Fine Particles by CVD [Translated] †

Kikuo Okuyama

Papers

Preparation of aluminium doped zinc oxide particles by chemical vapor deposition

Heterogeneous Condensation on Nanoparticle

Preparation of Au/Ag Alloy Particles by Spray Pyrolysis and Its Applications

Synthesis of binary component metal oxide nanoparticles by flame spray pyrolysis (第3回 日韓資源リサイクル・材料科学に関する国際シンポジウム特集号)

Experimental Control of Preparation of Thin Film and Fine Particles by CVD [Translated] †

Synthesis of binary component metal oxide nanoparticles by flame spray pyrolysis (第3回日韓資源リサイクル・材料科学に関する国際シンポジウム特集号)