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Liang H.,University of Quebec | Chen G.,University of Quebec | Desinan S.,University of Quebec | Rosei R.,University of Trieste | And 5 more authors.
International Journal of Hydrogen Energy | Year: 2012

Ligand-free Ru nanoclusters supported on carbon black have been synthesized in situ for the first time from the reduction of RuCl 3 by ammonia-borane concomitantly with its hydrolysis process at room temperature, and their catalytic activity has been investigated. Well dispersed Ru nanoclusters (∼1.7 nm) are stabilized and immobilized by carbon black. Due to the small size and the absence of ligands on the surface, the Ru catalysts exhibit high catalytic activity, which is partly retained after 5 reaction cycles. A kinetic study shows that the catalytic hydrolysis of ammonia-borane is first order with respect to Ru catalyst concentration; the turnover frequency is 429.5 mol H 2 min -1 mol -1 Ru. The activation energy for the hydrolysis of ammonia-borane in the presence of Ru/C catalysts has been measured to be 34.81 ± 0.12 kJ mol -1, which is smaller than most of the values reported for other catalysts, including those based on Ru, for the same reaction. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source

Brown C.P.,University of Oxford | Brown C.P.,University of Rome Tor Vergata | Brown C.P.,University of Quebec | Brown C.P.,Italy Quebec Joint Laboratory in Nanostructured Materials for Energy | And 10 more authors.
ACS Nano | Year: 2012

Spider silk is a fascinating natural composite material. Its combination of strength and toughness is unrivalled in nature, and as a result, it has gained considerable interest from the medical, physics, and materials communities. Most of this attention has focused on the one to tens of nanometer scale: predominantly the primary (peptide sequences) and secondary (β sheets, helices, and amorphous domains) structure, with some insights into tertiary structure (the arrangement of these secondary structures) to describe the origins of the mechanical and biological performance. Starting with spider silk, and relating our findings to collagen fibrils, we describe toughening mechanisms at the hundreds of nanometer scale, namely, the fibril morphology and its consequences for mechanical behavior and the dissipation of energy. Under normal conditions, this morphology creates a nonslip fibril kinematics, restricting shearing between fibrils, yet allowing controlled local slipping under high shear stress, dissipating energy without bulk fracturing. This mechanism provides a relatively simple target for biomimicry and, thus, can potentially be used to increase fracture resistance in synthetic materials. © 2012 American Chemical Society. Source

Chen G.,INRS - Institute National de la Recherche Scientifique | Desinan S.,INRS - Institute National de la Recherche Scientifique | Nechache R.,INRS - Institute National de la Recherche Scientifique | Rosei R.,University of Trieste | And 5 more authors.
Chemical Communications | Year: 2011

Core-shell structured Ni@Ru bimetallic nanoparticles are demonstrated as a bifunctional nanoplatform system for the hydrolysis reaction of ammonia-borane and also for magnetic separation. © 2011 The Royal Society of Chemistry. Source

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