Nanoparticles synthesis methods

T able 1 Upconverting nanoparticles, synthesis methods and ligands... 

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... 

Liquid-phase reductive deposition as a novel nanoparticle synthesis method and its application to supported noble metal catalyst preparation, Y. Sunagawa, K. Yamamoto, H. Takahashi, and A. Muramatsu, Catal Today, 2008,132, 81. 

In the XRD patterns of the unprotected metal nanoclusters prepared by the alkaline EG synthesis method, no signals derived from their corresponding oxides could be detected. XPS measurements also revealed that the prepared metals nanoparticles had the binding energies close to those of their corresponding zero valence species, 70.9 eV for Pt 4f7/2, 280.0 eV for Ru 3ds/2, 307.1 eV for Rh 3d5/2 and 50.0 eV for Os 4f7/2, respectively, indicating that the metal species were in a metallic state. 

Xin and co-workers modified the alkaline EG synthesis method by heating the metal hydroxides or oxides colloidal particles in EG or EG/water mixture in the presence of carbon supports, for preparing various metal and alloy nanoclusters supported on carbon [20-24]. It was found that the ratio of water to EG in the reaction media was a key factor influencing the average size and size distribution of metal nanoparticles supported on the carbon supports. As shown in Table 2, in the preparation of multiwalled carbon nanotube-supported Pt catalysts... 

The small metal particle size, large available surface area and homogeneous dispersion of the metal nanoclusters on the supports are key factors in improving the electrocatalytic activity and the anti-polarization ability of the Pt-based catalysts for fuel cells. The alkaline EG synthesis method proved to be of universal significance for preparing different electrocatalysts of supported metal and alloy nanoparticles with high metal loadings and excellent cell performances. 

Among various methods to synthesize nanometer-sized particles [1-3], the liquid-phase reduction method as the novel synthesis method of metallic nanoparticles is one of the easiest procedures, since nanoparticles can be directly obtained from various precursor compounds soluble in a solvent [4], It has been reported that the synthesis of Ni nanoparticles with a diameter from 5 to lOnm and an amorphous-like structure by using this method and the promotion effect of Zn addition to Ni nanoparticles on the catalytic activity for 1-octene hydrogenation [4]. However, unsupported particles were found rather unstable because of its high surface activity to cause tremendous aggregation [5]. In order to solve this problem, their selective deposition onto support particles, such as metal oxides, has been investigated, and also their catalytic activities have been studied. 

Doping is important for semiconductors in order to tune their optical and electrical properties for the potential applications in biotechnology and solar cells [65]. Ag-doped hexagonal CdS nanoparticles were successfully obtained by an ultrasound-assisted microwave synthesis method. Here, the doping of Ag in to CdS nanoparticles induced the evolution of crystal structure from cubic to hexagonal. Further support from photocatalytic experiment also clearly indicates the doping of Ag clusters into the CdS matrix. 

What are the advantages of Bonnemann s method of colloidal nanoparticle synthesis ... 

In this chapter, the first section will focus on the designs of different structures of DDSNs. The basic synthesis methods of pure silica nanoparticles will be briefly summarized at the beginning. The general methods for doping dye molecules into a silica matrix will then be covered followed by the introduction of several DDSN designs. The second section will be a major focus of this chapter. Various advantageous properties of DDSNs will be discussed. These discussions will involve reaction kinetics, solubility, photostability, and fluorescence intensity including quantum yield and lifetime, as well as toxicity. With the rapid development of DDSNs, more features and functionalities of DDSNs are expected in the near future. 

Fe(CO)s], [Fe2(CO)g], [Co2(CO)8] and [Os3(CO)i2]) have been reacted with dicyanobenzene to form intrazeolite [M(Pc)] complexes [140]. Another class of materials prepared by the intrazeolite template synthesis method has been mixed ligand metal carbonyls and metal carbonyl clusters, frequently by reductive car-bonylation of metal ions in zeolite cages [175]. However, because these are frequently decomposed in situ to form, for example, nanoparticles, they are outside the scope of this chapter, and will be considered here only when they are used as precursors for metal complexes. 

There are various methods available for the synthesis of 1-100 nm diameter nanoparticles. Whatever the synthesis method, it is important to consider their stability in terms of composition and size. 

The advances in nanotechnology and synthesis methods have enabled nanomaterials to be produced in various shapes and structures. Coating of a luminescent layer activated by lanthanide ions on nanoparticles such as SiC>2 or AI2O3 is one of such approaches to develop new nanophosphors. In section 6, we review recent work on interesting spectroscopic features and luminescence dynamics of lanthanide ions in other novel low-dimensional nanostructures including core-shell, one-dimensional (ID) nanowires and nanotubes, two-dimensional (2D) nanofilms, hollow nanospheres, 2D nanosheet and nanodisk which have also attracted extensive attention. 

---