Sonochemical preparation, nanoparticles

Okitsu K, Nagaoka S, Tanabe S, Matsumoto H, Mizukoshi Y, Nagata Y (1999) Sonochemical preparation of size-controlled palladium nanoparticles on alumina surface. Chem Lett 28 271-272... 

Okitsu K, Yue A, Tanabe S, Matsumoto H (2000) Sonochemical preparation and catalytic behavior of highly dispersed palladium nanoparticles on alumina. Chem Mater 12 3006-3011... 

Vinodgopal K, He Y, Ashokkumar M, Grieser F (2006) Sonochemically prepared platinum-ruthenium bimetallic nanoparticles. J Phys Chem B 110 3849-3852... 

Mizukoshi Y, Seino S, Okitsu K, Kinoshita T, Otome Y, Nakagawa T, Yamamoto TA (2005) Sonochemical preparation of composite nanoparticles of Au/y—Fe203 and magnetic separation of glutathione. Ultrason Sonochem 12 191-195... 

Mizukoshi Y, Okitsu K, Yamamoto T, Oshima J, Nagata Y, Maeda Y (1997) Sonochemical preparation of bimetallic nanoparticles of gold/palladium in aqueous solution. J Phys Chem B 101 7033-7037... 

Sonochemical Preparation of Monometallic, Bimetallic and Metal-Loaded Semiconductor Nanoparticles... 

Abstract A convenient method to synthesize metal nanoparticles with unique properties is highly desirable for many applications. The sonochemical reduction of metal ions has been found to be useful for synthesizing nanoparticles of desired size range. In addition, bimetallic alloys or particles with core-shell morphology can also be synthesized depending upon the experimental conditions used during the sonochemical preparation process. The photocatalytic efficiency of semiconductor particles can be improved by simultaneous reduction and loading of metal nanoparticles on the surface of semiconductor particles. The current review focuses on the recent developments in the sonochemical synthesis of monometallic and bimetallic metal nanoparticles and metal-loaded semiconductor nanoparticles. 

Takagi E, Mizukoshi Y, Oshima R, Nagata Y, Bandow H, Maeda Y (2001) Sonochemical preparation of noble metal nanoparticles in the presence of various surfactants. Stud Surf Sci Catal 132 335-338... 

Dhas NA, Zaban A, Gedanken A (1999) Surface synthesis of zinc sulfide nanoparticles on silica microspheres sonochemical preparation, characterization, and optical properties. Chem Mater 11(3) 806-813... 

Salkar RA, Jeevanandam P, Aruna ST, Yuri K, Gedanken A (1999) The sonochemical preparation of silver nanoparticles. J Mater Chem 9 1333-1335... 

Y. Koltypin, S. I. Nikitenko, and A. Gedanken, The sonochemical preparation of tungsten oxide nanoparticles, J. Mater. Chem. 12, 1107-1110 (2002). 

Gedanken and his group were searching to replace the Ni(CO)4, which was the source for the preparation of nickel, and is known to be a hazardous material. They found [67] a new precursor for the sonochemical preparation of amorphous nickel, Ni(cyclooctadiene)2, which yielded relatively large (200 nm) amorphous nanoparticles composed of nickel and carbon atoms. Small nickel particles were dispersed all over the particle. When these particles were heated slightly above their crystallization temperature, much smaller particles (5 nm) of encapsulated crystalline nickel in amorphous carbon were obtained. The XPS spectrum reveals that the crystallization process is also accompanied by the reduction of the surface Ni+ ions by the amorphous carbon atoms. The DSC measurements substantiate this assumption. 

A long list of oxides was prepared sonochemically. Almost all the above-mentioned oxides were synthesized in organic solvents. The other oxides that will be discussed from here on were all prepared in aqueous solutions. Submicron size spheres of silica and alumina prepared by well-known methods were coated sonochemically by nanoparticles of oxides of europium and terbium using the same concentration of ions [81]. We have also used sonochemistry to prepare nanoparticles of silica and alumina doped with the same rare-earth ions for comparison. The highest luminescence intensities were observed for europium and terbium doped in nanoparticles of alumina of dimension 20-30 run. The intensities are comparable or higher than in commercial phosphors. 

Okitsu K, Mizukoshi Y, Bandow H, Maeda Y, Yamamoto T, Nagata Y. Formation of the noble metal nanoparticles by ultrasonic irradiation. Ultrason Sonochem. 1996 3 S249-51. Okitsu K, Bandow H, Maeda Y. Sonochemical preparation of ultrafine palladium nanoparticles. Chem Mater. 1996 8 315-7. 

The hydrazinium nickel hydrazine carboxylate complex, (N2H5)Ni (N2H3C00)3-H20, is also used as precursor for the synthesis of metallic Ni in the sonochemical preparation of Ni-Mo-S/Al203, since volatile Ni precursors such as Ni(CO)4 are exceptionally toxic and dangerous to use [24]. Similarly, copper hydrazine carboxylate is used to prepare nanoparticles of copper by the sonication method [25]. The presence of a zwitterionic surfactant in the synthesis procedure causes the formation of elongated nanoparticles of aspect ratio 10, which is of significance for electrical applications. In the absence of the zwitterionic surfactant only spherical particles result [26]. 

Other one-pot preparations of bimetallic nanoparticles include NOct4(BHEt3) reduction of platinum and ruthenium chlorides to provide Pto.sRuo.s nanoparticles by Bonnemann et al. [65-67] sonochemical reduction of gold and palladium ions to provide AuPd nanoparticles by Mizukoshi et al. [68,69] and NaBH4 reduction of dend-rimer—PtCl4 and -PtCl " complexes to provide dend-rimer-stabilized PdPt nanoparticles by Crooks et al. [70]. 

Vinodgopal et al. prepared Pt/Ru bimetallic nanoparticles by sonochemical reduction of Pt(II) and Ru(III) in aqueous solutions. TEM images indicated that sequential reduction of the Pt(II) followed by the Ru(III) produced Pt-core/Ru-shell bimetallic nanoparticles. In the presence of sodium dodecyl sulfate (SDS), as a stabilizer, the nanoparticles had diameters between 5 and 10 nm. When PVP was used as the stabilizer, the rate of reduction is much faster, giving ultrasmall bimetallic nanoparticles of ca. 5nm diameter [141]. 

Kan et al. reported preparation of Au-core/Pd-shell bimetallic nanoparticles by successive or simultaneous sonochemical irradiation of their metal precursors in ethylene glycol, respectively. In the successive method, Pd clusters or nanoparticles are first formed by reduction of Pd(N03)2, followed by adding HAUCI4 solution. As a result, Au-core/Pd-shell structured particles are formed, although Pd-core/Au-shell had been expected. In their investigations, the successive method was more effective than the simultaneous one in terms of the formation of the Au-core/Pd-shell nanoparticles [143]. 

Aqil A, Serwas H, Delplancke JL (2008) Preparation of stable suspensions of gold nanoparticles in water by sonoelectrochemistry. Ultrason Sonochem 15 1055-1061... 

It has been reported that bimetallic nanoparticles with core/shell structure can be prepared by ultrasonic irradiation. Mizukoshi et al. reported the formation of bimetallic nanoparticles of Au core/Pd shell structure [42,43] from the sonochemical reduction of Au(III) and Pd(II), where the stepwise reduction of metal ions was observed to proceed during ultrasonic irradiation. That is, the reduction of Pd(II) started after the reduction of Au(III) finished. Vinodgopal et al. reported... 

Catalytic activities of Au core/Pd shell bimetallic nanoparticles have also been investigated [43,44], Okitsu et al. reported that catalytic activities are closely related to the nanostructure of bimetallic nanoparticles [44], where Au core/Pd shell bimetallic nanoparticles on and inside Si02 are prepared by consecutive sonochemical and sol-gel processes. 

As described in this chapter, the sonochemical reduction technique appears to be a promising method for the preparation of various types of metal nanoparticles in an aqueous solution. By choosing more efficient organic additives, easily-reducible metal precursors, supports and templates with an appropriate role, more advanced functional nanoparticles could be synthesized successfully using the sonochemical reduction technique. In future, it is also possible to develop effective synthetic methods by combining the sonochemical method with other chemical methods. 

Mizukoshi Y, Takagi E, Okuno H, Oshima R, Maeda Y, Nagata Y (2001) Preparation of platinum nanoparticles by sonochemical reduction of the Pt(IV) ions role of surfactants. Ultrason Sonochem 8 1-6... 

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