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Al Jubayl, Saudi Arabia

Sasaki K.,Brookhaven National Laboratory | Naohara H.,Toyota Motor Corporation | Choi Y.,Brookhaven National Laboratory | Choi Y.,Sabic Technology Center | And 4 more authors.
Nature Communications | Year: 2012

Stability is one of the main requirements for commercializing fuel cell electrocatalysts for automotive applications. Platinum is the best-known catalyst for oxygen reduction in cathodes, but it undergoes dissolution during potential changes while driving electric vehicles, thus hampering commercial adoption. Here we report a new class of highly stable, active electrocatalysts comprising platinum monolayers on palladium-gold alloy nanoparticles. In fuel-cell tests, this electrocatalyst with its ultra-low platinum content showed minimal degradation in activity over 100,000 cycles between potentials 0.6 and 1.0 V. Under more severe conditions with a potential range of 0.6-1.4 V, again we registered no marked losses in platinum and gold despite the dissolution of palladium. These data coupled with theoretical analyses demonstrated that adding a small amount of gold to palladium and forming highly uniform nanoparticle cores make the platinum monolayer electrocatalyst significantly tolerant and very promising for the automotive application of fuel cells. © 2012 Macmillan Publishers Limited. All rights reserved. Source

Alshaiban A.,Sabic Technology Center | Soares J.B.P.,University of Waterloo
Macromolecular Reaction Engineering | Year: 2013

The effect of adding hydrogen and/or electron donor on the microstructure of polypropylene polymerized with a 4th generation Ziegler-Natta catalysts at two temperatures on the molecular weight distribution, tacticity, and crystallinity of polypropylene is thoroughly investigated in this article. Polypropylene tacticity and crystallinity increases not only when external donors are added, but also when hydrogen is used as a chain transfer agent. The molecular weight distribution of the resins is deconvoluted into several Flory's most probable distributions to show how different active site types respond to the presence of electron donor and hydrogen. The effect of adding hydrogen (H) and/or an electron donor (D) on the microstructure of polypropylene produced with a 4th generation Ziegler-Natta catalysts at two temperatures on the molecular weight distribution and tacticity of polypropylene is thoroughly investigated in this paper. The figure shows how CEF (tacticity) profiles of polypropylene are significantly affected as these conditions are varied at 70°C. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

In this paper two time dimensional physics and scale invariance frequency based space-time discrete symmetry model has been introduced for unification of dynamical laws of microscopic and high scale objects of nature within one unified concept of classic physics. The physics with two time dimensions involves a new kind of discrete space-time dynamic symmetry with 2+2 D symmetric space and time dimensions forming background state for all of the forces. By discrete space-time symmetry concept gravitation is the conservation of energy distributed in the dynamic space-time frame, therefore it is time related phenomenon and can not be described by one time dimension. The two time dimensional physics is the necessary conceptual foundation for cyclic nature of events with conservation of energy and momentum within one conserved spacetime framework. Formation of space-time frame from uniform space-time annihilations generates an energetic field which through consequences of interactions of forces and particles moves the space-time portion back to the initial state of space-time annihilation. The model involves the correlation of the space-time discrete symmetry with the energy/momentum conservation which leads to the fundamental dynamic super symmetry concept for unification of forces. The concept that energy cannot be created and destroyed, following from Neother's theorem, in the case of dynamical events is to be extended with time translational symmetry of 2+2 D space-time frame to 3+1D with energy/momentum conservation. This concept involves a new mathematical idea of correlation of the space/time derivative operator with original space/time function as an extension of mathematical tool of differentiation. By space-time discrete symmetry concept the performance of nuclear is not regulated by continuum rotation of an electron around the nuclear, described by quantum model, but stable existence of nuclear is due to the cyclic high frequency discrete protonneutron annihilations. The discrete performance of proton/neutron pair involves the correlation and exchange of electromagnetic and gravitation forces with dynamic 2:1 resonance of "elementary quark ingredients" of nuclear and discrete isospin rotation of electron family ingredients. The classic discrete space-time symmetry concept of an electron presented in this paper describes the dynamics of appearance/disappearance model of universe in its cyclic performance. The phenomenal behavior of the background 2+2D space-time discrete symmetry generates the cyclic performance of nuclear and natural events. © EuroJournals Publishing, Inc. 2010. Source

Kuttiyiel K.A.,Brookhaven National Laboratory | Sasaki K.,Brookhaven National Laboratory | Choi Y.,Brookhaven National Laboratory | Choi Y.,Sabic Technology Center | And 3 more authors.
Nano Letters | Year: 2012

We describe a route to the development of novel PtNiN core-shell catalysts with low Pt content shell and inexpensive NiN core having high activity and stability for the oxygen reduction reaction (ORR). The PtNiN synthesis involves nitriding Ni nanoparticles and simultaneously encapsulating it by 2-4 monolayer-thick Pt shell. The experimental data and the density functional theory calculations indicate nitride has the bifunctional effect that facilitates formation of the core-shell structures and improves the performance of the Pt shell by inducing both geometric and electronic effects. Synthesis of inexpensive NiN cores opens up possibilities for designing of various transition metal nitride based core-shell nanoparticles for a wide range of applications in energy conversion processes. © 2012 American Chemical Society. Source

Hudson M.R.,U.S. National Institute of Standards and Technology | Hudson M.R.,University of Maryland University College | Queen W.L.,U.S. National Institute of Standards and Technology | Mason J.A.,University of California at Berkeley | And 5 more authors.
Journal of the American Chemical Society | Year: 2012

Low-pressure adsorption of carbon dioxide and nitrogen was studied in both acidic and copper-exchanged forms of SSZ-13, a zeolite containing an 8-ring window. Under ideal conditions for industrial separations of CO 2 from N 2, the ideal adsorbed solution theory selectivity is >70 in each compound. For low gas coverage, the isosteric heat of adsorption for CO 2 was found to be 33.1 and 34.0 kJ/mol for Cu- and H-SSZ-13, respectively. From in situ neutron powder diffraction measurements, we ascribe the CO 2 over N 2 selectivity to differences in binding sites for the two gases, where the primary CO 2 binding site is located in the center of the 8-membered-ring pore window. This CO 2 binding mode, which has important implications for use of zeolites in separations, has not been observed before and is rationalized and discussed relative to the high selectivity for CO 2 over N 2 in SSZ-13 and other zeolites containing 8-ring windows. © 2012 American Chemical Society. Source

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