Nanoparticle characterization methods

Principally purification and characterization methods of monometallic nanoparticles are directly applied to those of bimetallic nanoparticles. Purification of metal nanoparticles dispersed in solution is not so easy. So, in classical colloid chemistry, contamination is carefully avoided. For example, people used pure water, distilled three times, and glass vessels, cleaned by steam, for preparation of colloidal dispersions. In addition, the reagents which could not byproduce contaminates were used for the preparation. Recently, however, various kinds of reagents were used for the reaction and protection. Thus, the special purification is often required especially when the nanoparticles are prepared by chemical methods. 

After purification, the bimetallic nanoparticles are offered to characterization. The characterization techniques were well reviewed previously in literatures [1,2]. In this section, we highlight recent reports on the characterization methods of bimetallic nanoparticles after presenting some previous researches again. 

A) Elaboration of PLLA-based superparamagnetic nanoparticles Characterization, magnetic behavior study and in vitro relaxivity evaluation Abstract. Oleic acid-coated magnetite has been encapsulated in biocompatible magnetic nanoparticles (MNP) by a simple emulsion evaporation method. 

Transmission electron microscopy (TEM) can provide valuable information on particle size, shape, and structure, as well as on the presence of different types of colloidal structures within the dispersion. As a complication, however, all electron microscopic techniques applicable for solid lipid nanoparticles require more or less sophisticated specimen preparation procedures that may lead to artifacts. Considerable experience is often necessary to distinguish these artifacts from real structures and to decide whether the structures observed are representative of the sample. Moreover, most TEM techniques can give only a two-dimensional projection of the three-dimensional objects under investigation. Because it may be difficult to conclude the shape of the original object from electron micrographs, additional information derived from complementary characterization methods is often very helpful for the interpretation of electron microscopic data. 

In the case of LASIP with clay nanoparticles, polystyrene was grafted using a DPE coinitiator. The montmorillonite clay surface and intergallery interfaces were intercalated with 1,1-diphenylethylene (DPE) modified to be an organic cation as shown in Fig. 4. Its intercalation was confirmed by a series of characterization methods including X-ray diffraction (XRD), FT-IR spectroscopy, TGA, and XPS. The results showed a complete replacement of... 

Just as DENs particle sizes have some distribution (albeit relatively narrow), there is surely some distribution in particle compositions for bimetallic DENs. This is a fundamentally important aspect of DENs, particularly with regard to their catalytic properties however, there are presently no reliable characterization methods for evaluating particle composition distributions. One method that has been applied to PdAu [21] and PtPd [19] DENs, as well as dendrimer-templated PtAu [24] is to collect single particle EDS spectra from several (15-20) nanoparticles. These experiments indicate that individual particle composition distributions may vary widely, but the difficulty in obtaining data from the smallest particles may skew the results somewhat. EDS spectra collected over large areas, which sample tens or hundreds of particles, generally agree well with the bulk composition measurements [24] and with stoichiometries set in nanoparticle synthesis [19,21,24]. 

The combined information obtained by the different characterization methods applied allows the conclusion that deposits of ruthenium oxide at BDD, ranging from approximately one hundredth of a monolayer, maintain the physicochemical properties of RUO2, which proves the very limited degree of chemical interaction with the support. The deposits are most probably organized in nanoparticles growing around nucleation sites. When particles and clusters of particles reach a size of 50-60 nm, their charge-storage and catalytic behavior closely resembles that of thick oxide films. 

Solution combustion method is a single step process that produces nanoparticles characterized by their high surface area. The NS-Ti02 produced by this method has been successfully applied in the... 

Several aerosol nanoparticle reactors have been built and characterized in which one or more convenient process parameters can be used to control the particle size distribution, including particle diameter and number concentration. To address the diverse needs of the NOSH Consortium membership, various aerosol nanoparticle synthesis methods have been employed, including thermal decomposition of hquid precursor vajxrrs, spray atomization of hquids of soluble materials or solid susjjensions, and thermal vaporization of solid metals. These aerosol nanoparticle reactors are used in subsequent NOSH Consortium activities as detailed in the remaining... 

Myers VS, Weir MG, Carino EV, Yancey DF, Pande S, Crooks RM (2011) Dendrimer-encapsulated nanoparticles new synthetic and characterization methods and cattilytic applications. Chem Sci 2 1632... 

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