Metal nanoparticles, sonochemical synthesis solution

Although various techniques have been reported, sonochemical reduction technique for the synthesis of metal nanoparticles in an aqueous solution are reviewed in this chapter. 

It is also observed in Fig. 5.3 that Pd(II) ions are partly adsorbed on AI2O3 before ultrasonic irradiation the concentration of Pd(II) just before irradiation becomes ca. 0.8 mM, although 1 mM Pd(II) was added in the sample solution. From a preliminary adsorption experiment, the rate of Pd(II) adsorption on A1203 was found to be slow compared with those of Pd(II) reduction in the presence of alcohols. Therefore, it is suggested that the sonochemical reduction of Pd(II) in the presence of alcohols mainly proceeds in the bulk solution. The mechanism of the Pd/Al203 formation is also described in the section of sonochemical synthesis of supported metal nanoparticles. 

Metal nanoparticles can be prepared in a myriad of ways, e.g., by pulse radiolysis [110], vapor synthesis techniques [111], thermal decomposition of organometallic compounds [112], sonochemical techniques [113,114], electrochemical reduction [115,116], and various chemical reduction techniques. Some of the most frequently used reducing agents include alcohols [117,118], citrate [119,120], H2 [121], borohydrides [122], and, more recently, superhydride [123]. The chosen experimental conditions determine the size, size distribution, shape, and stability of the particles. Because naked metal particles tend to aggregate readily in solution, stabilizing the nanoparticles is the key factor for a successful synthesis. Sometimes the solvent can act as a stabilizer, but usually polymers and surfac-... 

Various groups have employed a range of sonochemical approaches to s mthesize metal sulfate nanoparticles in aqueous solution. Wang et al. [194] have reported the sonochemical synthesis of CdS nanoparticles by irradiation of a mixture of cadmium chloride, sodium thiosulfate, and 2-propanol. Dhas et al. [191] have reported the surface synthesis of CdS nanoparticles on silica microspheres by using cadmium sulfate and thiourea as precursors. The mechanism of the sonochemical growth of metal particles consists of several steps. For example, ZnO/CdS core/shell-type composite particles are formed by four steps [195] ... 

Abstract This chapter discusses the effect of ultrasound propagation in water and aqueous solutions, in the atmosphere of inert and reactive gases. Sonochemical studies of aqueous solutions of divalent and trivalent metal ions and their salts have been reviewed and the precipitation behaviour of hydroxides of metal ions has been discussed. Synthesis of nanoparticles of many metals using ultrasound and in aqueous solutions has also been discussed briefly. Besides, the nephelometric and conductometric studies of sonicated solutions of these metal ions have been reported. 

The synthesis of nanostructured inorganic materials by sonochemical had already been synthesized a large number of nanostructures of different compositions with comparable or better than the properties of the same when summed with other preparation methods. The versatility of this method also extends to the relative flexibility of reaction conditions such as the nature of the precursors and their solutions, the possibility of addition of auxiliaries, and the presence of traps (species immobilized) to the nanoparticles. All types of metallic nanostructured materials synthesized by sonochemical described (powders, colloids, or nanoparticles supported) can also be obtained for other classes of compounds such as oxides [58-60], sulfides [61], Suslick [20, 62], and more recently selenides [63, 64] and tellurides [65]. 

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