Sonochemical Preparation of Ultrafine Particles

A central focus of recent work in material chemistry has been the preparation of ultrafine particles, for which a variety of chemical and physical methods has been applied metal evaporation, decomposition of organometallics, controlled reduction of salts. 5 gonochemical decomposition of organometallic 

When precursors are sonicated in high-boiling alkanes, e.g., decane or hexa-decane, nanostructured powders are formed. Using a polymeric ligand [e.g., polyvinylpyrrolidone (PVP)] or inorganic supports (silica, alumina, etc.), nanophase metal colloids, and nanostructured supported metal catalysts are generated, with very interesting catalytic activity. 

Cichowslav, A.A. Suslick, K.S. Division of Petroleum Chemistry Symp. Advanced Techniques in Catalyst Preparations, ACS Proc. National Meeting 1995. 

The runs reported in the figure above have been performed with a silica-supported nanostructured iron catalyst prepared under sonication (Fe loading wt% = 10.94, dispersion Dm% = 1.85) compared to the conventional silica-supported crystalline iron catalyst prepared by the incipient wetness method (Fe wt% = 9.91, Dm% = 1-86). The catalysts were tested with H2/CO = 3.48 and 1 bar. 

Many other examples dealing with the preparation of ultrafine particles are present in the literature, especially concerning the preparation of particles of noble metals. In particular, it was foimd that stable fine particles of palladium are readily produced from an aqueous solution of tetrachloropalladate ions and in the presence of a protective agent such as a surfactant or a water-soluble polymer.il jhis method was used for the preparation of gold particles from an aqueous solution of NaAuC. i In this case as well, the formation of such particles was accelerated in the presence of organic additives such as surfactants, water-soluble polymers, and aliphatic alcohols and ketones. The formation of 

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