Alloy nanoparticle

Bimetallic nanoparticles, either as alloys or as core-shell structures, exhibit unique electronic, optical and catalytic properties compared to pure metallic nanopartides [24]. Cu-Ag alloy nanoparticles were obtained through the simultaneous reduction of copper and silver ions again in aqueous starch matrix. The optical properties of these alloy nanopartides vary with their composition, which is seen from the digital photographs in Fig. 8. The formation of alloy was confirmed by single SP maxima which varied depending on the composition of the alloy. 

M1M2 - All kinds of bimetallic nanoparticles including random alloy nanoparticles. In this case Mi and M2 should be arranged in an alphabetical order. 

Ag-core/Au-shell bimetallic nanoparticles were prepared by NaBH4 reduction method [124]. UV-Vis spectra were recorded and compared with various ratios of AuAg alloy nanoparticles. The UV-Vis spectra of bimetallic nanoparticles suggested the formation of core/shell structure. Furthermore, the high-resolution transmission electron microscopy (HRTEM) image of the nanoparticles confirmed the core/shell type configuration directly. 

By XPS spectra, Endo et al. [96] confirmed that formation of binary structure prevented Pd atoms from oxidation in the AuPd and PtPd bimetallic nanoparticles which exhibited higher catal5hic activity than monometallic ones. Wang et al. [112]. characterized PtCu bimetallic alloy nanoparticles Ijy XPS. XPS revealed that both elements in the nanoparticles are in zero-valence and possess the characteristic metallic binding energy. 

Digestive Ripening as a Route to Create Alloy Nanoparticles Silver-Gold and Copper-Gold [59]... 

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. 

Scheme 3. Reaction mechanism of Au-Ag alloy nanoparticle formation.

Table 3 shows properties of Au-Ag alloy nanoparticles obtained by this preparative procedure. 

The solvent-free controlled thermolysis of metal complexes in the absence or presence of amines is the simple one-pot synthesis of the metal nanoparticles such as gold, silver, platinum, and palladium nanoparticles and Au-Ag, Au-Pt, and Ag-Pd alloy nanoparticles. In spite of no use of solvent, stabilizer, and reducing agent, the nanoparticles produced by this method can be well size regulated. The controlled thermolysis in the presence of amines achieved to produce narrow size dispersed small metal nanoparticles under milder condition. This synthetic method may be highly promising as a facile new route to prepare size-regulated metal nanoparticles. Finally, solvent-free controlled thermolysis is widely applicable to other metal nanoparticles such as copper and nickel... 

Wang G, Van Hove MA, Ross PN, Baskes MI. 2005. Quantitative prediction of surface segregation in bimetaUic Pt-M alloy nanoparticles (M = Ni, Re, Mo). Prog Surf Sci 79 28-45. 

In order to obtain high mass activity of Pt, it is essential to disperse Pt or alloy nanoparticles on high surface area supports. Some questions then arise. What kind of alloys and composition should we choose Is there any good parameter for screening the catalysts What size of catalyst particles should we prepare to obtain the maximum performance Unfortunately, there has been much controversy about such issues in the literature. 

Yang H, Vogel W, Lamy C, Alonso-Vante N. 2004. Structure and electrocatalytic activity of carbon-supported Pt-Ni alloy nanoparticles toward the oxygen reduction reaction. J Phys ChemB 108 11024-11034. 

Dabala M, Pollet BG, Zin V et al (2008) Sonoelectrochemical (20 kHz) production of Co65Fe35 alloy nanoparticles from Aotani solutions. J Appl Electrochem 38 395-402... 

Liu YC, Yang KH, Yang SJ (2006) Sonoelectrochemical synthesis of spike-like gold-silver alloy nanoparticles from bulk substrates and the application on surface-enhanced Raman scattering. Anal Chim Acta 572 290-294... 

Chen YH, Yeh CS (2001) A new approach for the formation of alloy nanoparticles laser synthesis of gold-silver alloy from gold-silver colloidal mixtures. Chem Commun 371-372... 

Chimentao RJ, Cota I, Dafinov A, Medina F, Sueiras JE (2006) Synthesis of silver-gold alloy nanoparticles by a phase-transfer system. Mater Res 21 105-111... 

Some of the reports are as follows. Mizukoshi et al. [31] reported ultrasound assisted reduction processes of Pt(IV) ions in the presence of anionic, cationic and non-ionic surfactant. They found that radicals formed from the reaction of the surfactants with primary radicals sonolysis of water and direct thermal decomposition of surfactants during collapsing of cavities contribute to reduction of metal ions. Fujimoto et al. [32] reported metal and alloy nanoparticles of Au, Pd and ft, and Mn02 prepared by reduction method in presence of surfactant and sonication environment. They found that surfactant shows stabilization of metal particles and has impact on narrow particle size distribution during sonication process. Abbas et al. [33] carried out the effects of different operational parameters in sodium chloride sonocrystallisation, namely temperature, ultrasonic power and concentration sodium. They found that the sonocrystallization is effective method for preparation of small NaCl crystals for pharmaceutical aerosol preparation. The crystal growth then occurs in supersaturated solution. Mersmann et al. (2001) [21] and Guo et al. [34] reported that the relative supersaturation in reactive crystallization is decisive for the crystal size and depends on the following factors. 

Synthesis of gold, silver and their alloy nanoparticles using bovine serum albumin as foaming and stabilizing agent. Journal of Materials Chemistry, 15, 5115-5121. 

Figure 15.21 shows a schematic representation of the SCCO2 treatment effect for promoting the internal diffusion of metal ions to prepare Rh and RhPt alloy nanoparticles in mesoporous FS-16 and HMM-1. The supercritical phase displays both liquid and gas properties at the same time. SCFs can also dissolve various metal precursors, which promotes their mobiUty and surface-mediated reaction to form nanoparticles by the hydrogen reduction in the mesoporous cavities of... 

Zhou S, Yin H, Wu Z et al (2008) NiAu alloy nanoparticles for preparing highly active Au/ NiOx CO oxidation catalysts. Chem Phys Chem 9 2475-2479... 

Liu Z, Jackson G, Eichhom B (2010) PtSn intermetallic, core-shell and alloy nanoparticles as CO-tolerant electrocatalysts for H2 oxidation. Angew Chem Int Ed 49 3173-3176... 

Maye MM, Luo J, Han L, Kariuki N, Rab Z, Khan N, Naslund HR, Zhong C-J (2004) Gold and alloy nanoparticle catalysts in fuel cell reactions. Div Fuel Chem 49 938-939... 

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