PtRu nanoparticles

PtRu nanoparticles can be prepared by w/o reverse micro-emulsions of water/Triton X-lOO/propanol-2/cyclo-hexane [105]. The bimetallic nanoparticles were characterized by XPS and other techniques. The XPS analysis revealed the presence of Pt and Ru metal as well as some oxide of ruthenium. Hills et al. [169] studied preparation of Pt/Ru bimetallic nanoparticles via a seeded reductive condensation of one metal precursor onto pre-supported nanoparticles of a second metal. XPS and other analytical data indicated that the preparation method provided fully alloyed bimetallic nanoparticles instead of core/shell structure. AgAu and AuCu bimetallic nanoparticles of various compositions with diameters ca. 3 nm, prepared in chloroform, exhibited characteristic XPS spectra of alloy structures [84]. 

PtRu nanoparticle electrocatalyst with bulk alloy properties prepared through a sono-chemical method Langmuir 22 10446-10450. 

Basnayake R, Li Z, Katar S, Zhou W, Rivera H, Smotkin ES, Casadonte DJ, Korzeniewski C Jr (2006) PtRu nanoparticle electrocatalyst with bulk alloy properties prepared through a sonochemical method. Langmuir 22 10446-10450... 

Fig. 7 Current density vs. Ru composition for PtRu nanoparticle electrodes at 0.3 V (A) and 0.4 V (B) vs. SHE measured after 20 hr of oxidation in 0.5 M methanol. The dashed line indicates a commercial Johnson Matthey catalyst.125... 

Wu, B., et al., Functionalization of carbon nanotubes by an ionic-liquid polymer Dispersion ofPt and PtRu nanoparticles on carbon nanotubes and their electrocatalytic oxidation of methanol. Angewandte Chemie International Edition, 2009. 48(26) p. 4751-4754. 

Some strategies for developing a polyol process capable of generating well-dispersed alloyed PtRu nanoparticles deposited on carbon supports have been also investigated. " Recently, Sau et alf reported how, by careful selection of the polyol, reaction pH, temperature, and modality of combining the reactants, it was possible to control not only the size and dispersion of the bimetallic nanoparticles but also the relative spatial distribution of the two elements. 

The microemulsion method has been also developed for preparing PtRu nanoparticles. Aqueous phase should contain platinum and ruthenium salts, with reducing agent and surfactants for microemulsification being located in organic phase. Triton X-100 and isopropanol were used for the latter purpose. ... 

The synthesis methods used for the preparation of carbon supported PtRuMo nanoparticles could be classified as adsorption of metal colloids onto the carbon surface, or impregnation of carbon support with metals precursor solution. Additionally, the incorporation of the metals has been carried out in a (1) one step method or with simultaneous incorporation of the three metals, and in (2) two step methods or sequential incorporation of Mo and PtRu nanoparticles ... 

Besides, ILs unit could be attached to the sidewall of CNTs by radical grafting, in which acid-oxidation pretreatment of CNTs could be avoided. Chen et al. reported that thermal-initiation free radical polymerization of the IL monomer 3-ethyl-l-vinylimidazolium tetrafluoroborate ([VEIM]BF4] on the CNT surface (Fig. 4.18a] [62]. Then under similar method, the Pt and PtRu nanoparticles with narrow size distribution (average diameter (1.3 0.4] nm for PtRu, (1.9 0.5] nm for Pt] are dispersed uniformly on the CNTs and show better performance in methanol electrooxidation than that without ILs units (Fig. 4.18b]. 

In the case of commercial MWCNTs as ftRu support, Jeng et al. [31] used this kind of support previously activated by chemical treatment. Well dispersed PtRu 1 1 nanoparticles of 3.5-4 nm were obtained by a polyol synthesis method. The fuel cell test showed a performance 50 % higher than that of a commercial PtRu on Vulcan support (E-TEK). Similar results were found by Prabhuram et al. [32] for PtRu on oxidized MWCNT, where well dispersed nanoparticles of 4 nm were obtained by the NaBH4 method. The DMFC performance test of PtRu supported on MWCNTs showed a power density ca. 35 % higher than that using the Vulcan carbon support. Outstanding results were obtained by Tsuji et al. [33] with PtRu nanoparticles supported on carbon nanofibers prepared by polyol method and tested in a DMFC. They obtained a performance 200 % higher than standard PtRu on Vulcan carbon from Johnson Matthey. 

OMC carbons obtained from replication of structured mesoporous silicas show a narrow pore size distribution, but with mesopores smaller (< 15 nm) than those obtained from colloidal replication. PtRu nanoparticles supported on ordered mesoporous carbon CMK-3 were analyzed by Din et al. [63] Although a good nanoparticle dispersion was obtained, the catalyst synthesized showed a worse performance than nanoparticles supported on Vulcan XC-72 for methanol oxidation. 

As it was discussed above, the carbon with small mesopores used as support produce high dispersion of the PtRu nanoparticles. However, in the fuel cell test they can show a poorer performance than the catalysts supported on Vulcan. Catalyst nanoparticles deposited in a tight pore might be tmconnected to the perfluorosulfonate ionomer and inaccessible to the methanol. However, other factors affect the triple phase boundary and in consequence the performance of the cell using small mesopores carbon supports. For example, the method of catalyst layer formation, including ink formation and dispersion of the catalyst... 

Joo and co-workers [22] have discussed a new type of composite membrane, consisting of functionalised carbon nanotubes (CNT) and sulfonated polyarylene sulfone (sPAS) for direct methanol fuel cell applications. The CNT modified with sulfonic acid or platinum-rubidium (PtRu) nanoparticles were dispersed within the sPAS matrix by a solution casting method to give SOs-CNT-sPAS or PtRu-CNT-sPAS composite membranes, respectively. Characterisation of the composite membranes revealed that the functionalised CNT were homogeneously distributed within the sPAS matrix and the composite membranes contained smaller ion clusters than the neat sPAS. The composite membranes exhibited enhanced mechanical properties in terms of tensile strength, strain and toughness, which leads to improvements in ion conductivity and methanol permeability compared with the neat sPAS membrane, which demonstrates that the improved properties of the composite membranes induce an increase in power density. The strategy for CNT-sulfonated composite membranes in this work can potentially be extended to other CNT-polymer composite systems. 

Bonnemann H, Brinkmann R, Kinge S, Ely TO, Armand M (2004) Chloride free Pt- and PtRu-nanoparticles stabilised by Armand s ligand as precursors for fuel cell catalysts. Fuel Cells 4 289-296... 

The most widely studied conducting polymer support is polyaniline (PANl), which has been shown to decrease the poisoning of Pt by COads [88]. Gharibi et al. have recently explored the factors responsible for the enhanced formic acid oxidation activity of Pt supported on a carbon/PANI composite [89]. They concluded that improvements in both electron and proton conductivities, as well as the increased methanol diffusion coefficient and decreased catalyst poisoning, could be involved. A carbon nanotubes/PANI composite [90], poly(o-methoxyaniline) [91], and polyindole [92] have recently been reported as effective supports for formic acid oxidation at Pt nanoparticles, while polycarbazole [93] has also been used to support PtRu nanoparticles. 

Wang H, Alden LR, Di Salvo FJ, Abruna HD (2009) Methanol electrooxidation on PtRu bulk alloys and carbon-supported PtRu nanoparticle catalysts a quantitative OEMS study. Langmuir 25 7725-7735... 

Ahn H-J, Moon WJ, Seong TY, Wang D (2009) Three-dimensional nanostructured carbon - nanotube array/PtRu nanoparticle electrodes for micro-fuel cells. Electrochem Commun 11 635-638... 

Zhao Y Gao Y, Zhan D, Liu H, Zhao Q, Kou Y, Shao Y, Li M, Zhuang Q, Zhu Z (2005) Selective detection of dopamine in the presence of ascorbic acid and uric acid by a carbon nanotubes-ionic liquid gel modified electrode. Talanta66(l) 51-57 Boennemann H, Brinkmann R, Kinge S, Ely TO, Armand M (2004) Chloride free Pt- and PtRu- nanoparticles stabilised by armand s ligand as precursors for fuel cell catalysts. Fuel Cells 4(4) 289-296... 

Kim et al. synthesized mesoporous earbon xerogels by sol-gel polymerization of resorcinol and formaldehyde using colloidal silica particles of 12 nm diameter as templates [275]. The main pore size range of the resulting carbon xerogels was between about 30—40 mn, and the BET surface areas varied as a function of the preparation pH between 321 m g" (at pH 1.5) and 654 m g (at pH 9). The PtRu nanoparticles synthesized and deposited on the support had diameters between 2.2 and 2.8 nm (the larger the support surface area, the smaller the catalyst particle size). 

Selvaraj V, Alagar M. Pt and PtRu nanoparticles decorated polypyrrole/multiwalled carhon nanotuhes and their catalytic activity towards methanol oxidation. Electrochem Comm 2007 9 1145-53. 

Figure 10.11. TEM images of microwave-sjmthesized PtRu nanoparticles supported on different carbon samples (a) Vulcan XC72 carbon (b) carbon nanotubes (nominal Pt loading, 20 wt% Ru loading, 10 wt%) [113]. (Reprinted with permission from Langmuir 2004 20 181-7. Copyright 2004 American Chemical Society.)...

Rojas S, Garcia-Garcia FJ, Jaras S, Martinez-Huerta MV, Fierro JLG, Boutonnet M. Preparation of carbon supported Pt and PtRu nanoparticles from microemulsion electrocatalysts for fuel cell applications. Appl Catal A 2005 285 24-35. 

Liu ZL, Lee JY, Chen WX, Han M, Gan LM. Ph5rsical and electrochemical characterizations of microwave-assisted polyol preparation of carbon-supported PtRu nanoparticles. Langmuir 2004 20 181-7. 

Deivaraj TC, Lee JY. Preparation of carbon-supported PtRu nanoparticles for direct methanol fuel cell applications - a comparative study. J Power Sources 2005 142 43-9. 

Chen W-X, Lee JY, Liu Z. Preparation of Pt and PtRu nanoparticles supported on carbon nanotubes by microwave-assisted heating polyol process. Mater Lett 2004 58 3166-9. 

He ZB, Chen JH, Liu DY, Zhou HH, Kuang YF. Elecfrodeposition of PtRu nanoparticles on carbon nanotubes and their electrocatalystic properties for methanol electrooxidation. Diam Relat Mater 2004 13 1764-79. 

Liu Z, Ling XY, Su X, Lee JY. Carbon-supported Pt and PtRu nanoparticles as catalysts for a direct methanol fuel cell. J Phys Chem B 2004 108 8234--40. 

Gomez de la Fuente, XL., Martinez-Huerta, M.M, Rojas, S., Terreros, R, Fierro, J.L.G. Pena, M.A. Enhanced methanol electrooxidation activity of PtRu nanoparticles supported on H2O2-functionalized carbon black. Carbon 43 (2005), pp. 3002-3005. 

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