Nano-platinum catalyst

The most successful binary catalyst for methanol oxidation is Pt-Ru alloy (Lin et al., 2009 Liu et al., 2008). On the other hand, investigations on a highly dispersed Pt-Ru alloy on a carbon-supported catalyst show that surface metal alloy domains of Ru Pt catalysts are the key for higher activity in DMFCs applications (Antolini and Cardellini, 2001 Sharma and PoUet, 2012). A proposed role for Ru in conjunction with Pt for methanol oxidation will be its function in enabling desorption of catalyst poisons from the Pt surface. For an optimum activity, Ru should be in sohd solution with Pt (Burstein et al., 1997). 

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Ordered mesoporous carbon-supported nano-platinum catalysts application in direct methanol fuel cells... 

Furthermore succeeds, with the support of hydrogen, the reductive transformation of supercritical carbon dioxide into nano-onions (CO2 -r2H2 C-F2H20). A platinum catalyst [Pt(T] -C,S-Ci2H8)(PEt3)2] is employed here which presumably releases [Pt(PEt3)2] as reactive species. The resultant carbon onions exhibit a partially spiral structure, or they form aggregates enclosed in a common shell. 

Moreover, in the specific case of ceria-supported platinum catalyst reduced at 1173 K or above, the HRTEM images have unequivocally shown the occurrence of an additional chemical/nano-structural effect consisting of the formation of an inter-metallic CePts phase. This implies the incorporation of heavily reduced cerium into the Pt lattice. No similar effect could be detected on Rh/Ce02 [353], By contrast, in Pd/Ce02 catalysts, though no inter-metallic phases have been observed, shifts in the XRD diffraction peaks assigned to Pd has been interpreted as due to some dissolution of Ce into the palladium lattice [401,415]. 

I. Ivanov, P. Petrova, V. Georgiev, T. Batakliev, Y. Karakirova, V. Serga, L. Kulikova, A. Eliyas, S. Rakovsky, Comparative study of ceria supported nano-sized platinum catalysts synthesized by extractive-pyrolytic method for low-temperature WGS reaction, Catal. Lett. 

In the present article, the size and the loading efficiency of metal particles were investigated by changing the preparation method of carbon-supported platinum catalysts. First, the effect of acid/base treatment on carbon blacks supports on the preparation and electroactivity of platinum catalysts. Secondly, binary carbon-supported platinum (Pt) nanoparticles were prepared using two types of carbon materials such as carbon blacks (CBs) and graphite nanofibers (GNFs) to check the influence of carbon supports on the electroactivity of catalyst electrodes. Lastly, plasma treatment or oxyfluorination treatment effects of carbon supports on the nano structure as well as the electroactivity of the carbon supported platinum catalysts for DMFCs were studied. 

In the present study, the size and the loading efficiency of metal particles were investigated by changing the preparation method of carbon-supported platinum catalysts. Furthermore, acld/base treatment effects of carbon blacks on the nano-structure as well as the electroactivity of the carbon-supported platinum catalysts for DMFCs were studied. 

In spite of the success in the optimization of platinum catalysts, a major breakthrough in the field of fuel cells is yet to be achieved. Especially, the desire for a significant cost reduction by the replacement of platinum motivates international research activities investigating new catalyst concepts for cathodes. Thereby, the cathodes have to be sufficiently stable under fuel cell conditions the alternative non-noble metal catalysts (NNMC) need to have a high selectivity for direct reduction of oxygen to water. The US department of energy (DOE) defined 25% of the achievable current density of a commercial platinum catalyst as target value for 2015. For fuel cell application, the catalysts should be producible in such a nano-structured form that suitable gas diffusion structures can be built. 

For most PEM fuel cell catalysts, carbon black and other order carbon materials (such as carbon nanotubes) are usually used as support materials. These supports can give catalysts good electron conductivity, a very important feature in a fuel cell catalyst. Platinum and its alloys are popular active components, generally highly dispersed on the surface of support materials as micro- and nano-particles. Catalyst performance is related not only to the conductivity and supporting amounts of noble metals, but also, and more importantly, to the dispersion and composition of the active components. Because the hydrogen molecule is small and easily diffused in catalysts, in general the catalyst pore structure is not more important than the surface area. 

Fujitsu has developed a MEA based on an aromatic hydrocarbon solid electrolyte material, coated with a high density of highly active platinum-based nano-particle catalyst, having less than one-tenth of the methanol crossover rate encountered with typical fluorinated polymers. Fig. 10 shows Fujitsu s 15 W micro fuel cell based on a new hydrocarbon solid electrolyte material that enables use of 30% methanol powering a note book PC. The basic specification of a 3.78 W prototype micro fuel cell is given in Table 2. 

EfiBdent hydrogen supply iiom decalin was only accomplished by the si terheated liquid-film-type catalysis under reactive distillation conditions at modaate heating tempaatures of 210-240°C. Caibcm-supported nano-size platinum-based catalysts in the si ietheated liquid-film states accelerated product desorption fixjm file catalyst surface due to its temperature gradient under boiling conditions, so that both hi reaction rates and conversions were obtained simultaneously. 

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