Metal salts Nanomaterials

Ffirai and Toshima have published several reports on the synthesis of transition-metal nanoparticles by alcoholic reduction of metal salts in the presence of a polymer such as polyvinylalcohol (PVA) or polyvinylpyrrolidone (PVP). This simple and reproducible process can be applied for the preparation of monometallic [32, 33] or bimetallic [34—39] nanoparticles. In this series of articles, the nanoparticles are characterized by different techniques such as transmission electronic microscopy (TEM), UV-visible spectroscopy, electron diffraction (EDX), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) or extended X-ray absorption fine structure (EXAFS, bimetallic systems). The great majority of the particles have a uniform size between 1 and 3 nm. These nanomaterials are efficient catalysts for olefin or diene hydrogenation under mild conditions (30°C, Ph2 = 1 bar)- In the case of bimetallic catalysts, the catalytic activity was seen to depend on their metal composition, and this may also have an influence on the selectivity of the partial hydrogenation of dienes. 

Hydrogenation of Compounds with C=C Bonds Hirai and Toshima have published several papers on the synthesis of transition metal nanopartides by alcoholic reduction of metal salts in the presence of a polymer such as polyvinyl alcohol (PVA), poly(methyl vinyl ether) (PMVE) or polyvinylpyrrolidone (PVP) in methanol (or ethanol) /water mixtures or in pure alcohols. This simple and reproducible process has been applied for the preparation of rhodium nanopartides from rhodium (III) trichloride [15]. The particles size of metallic fee rhodium is distributed in a narrow range, 3-7nm and the average diameter is 4nm. The PVP-stabilized Rh nanoparticies are more stable. These nanomaterials are effident catalysts for olefin and diene hydrogenation in rruld conditions (30 C PH2=lbar) as shown in Table 11.1. 

The description presented here focused mainly on metal-based nanomaterials. However, the same principles can find application and extension to the preparation of nanostructures made of organic polymers, oxides, and salts. 

ZnO nanoflower morphologies usually include nanowires, nanorods, nanorings, nanoneedles, etc. The synthetic techniques of nanomaterials include oxidation of elemental metals, reduction of metal salts, thermal decomposition of relatively unstable compounds, or electrochemical route. Various other metal nanoflowers have also been synthesized by various workers from time to time. 

Sonochemical routes also have been used to produce electroactive NPs. For example, metal hydroxides containing Ni(II), Co(II) and mixtures of both have been prepared from the appropriate metal nitrate salts using ammonium hydroxide as the hydrolytic agent [33,34]. This route produces metal-hydroxide NPs with diameters in the range of 2-10 nm. This method has been extensively applied in the synthesis of a wide variety of materials, including nanomaterials [35]. 

The dissolution rate and stability ofNMs over time is another crucial issue. Kittler et al. [32] have shown that the release of silver ions from a dispersion of silver nanoparticles in water, and consequently the toxicity towards human mesenchymal stem cells, increases significantly with time. In addition, the temperature and the nature of the biological medium (e.g., the presence of salts or biomolecules) are important factors influencing the dissolution of metal nanomaterials. Unfortunately, measurement of the dissolution... 

The accessibility of the amine groups in the lamellar nanomaterials as well as their chelating ability toward transition metal or lanthanide anhydrous salts was... 

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