The Experts below are selected from a list of 45480 Experts worldwide ranked by ideXlab platform
Rafael Luque - One of the best experts on this subject based on the ideXlab platform.
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microwave assisted valorization of pig bristles towards visible light photocatalytic chalcocite composites
Green Chemistry, 2018Co-Authors: Alessio Zuliani, Mario J Munozbatista, Rafael LuqueAbstract:Waste valorization for the production of valuable materials is of great importance for sustainable development. Herein, a new green methodology for the synthesis of photocatalytically active copper sulfide (Cu2S) carbon composites using pig bristles is reported. The catalyst was prepared via microwave-assisted methodology using ethylene glycol as the solvent, pig bristles as the sulfur and carbon source, and copper chloride as the Metal Precursor. Cu2S carbon composites (denoted as pb-Cu2S, where “pb” stands for “pig bristle”) were characterized by XRD, N2 physisorption, EDX and UV-Vis spectroscopy. In order to validate the practical utilization of pig bristle-derived chemicals, the photocatalytic degradation of methyl red using pb-Cu2S was investigated under white, blue, green and red visible light irradiation.
Somorjai, Gabor A. - One of the best experts on this subject based on the ideXlab platform.
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Seedless Polyol Synthesis and CO Oxidation Activity of Monodisperse (111) and (100)-Oriented Rhodium Nanocrystals in Sub-10 nm Sizes
Lawrence Berkeley National Laboratory, 2010Co-Authors: Zhang Yawen, Grass, Michael E., Huang Wenyu, Somorjai, Gabor A.Abstract:Monodisperse sub-10 nm (6.5 nm) sized Rh nanocrystals with (111) and (100) surface structures were synthesized by a seedless polyol reduction in ethylene glycol, with poly(vinylpyrrolidone) as a capping ligand. When using [Rh(Ac){sub 2}]{sub 2} as the Metal Precursor, (111)-oriented Rh nanopolyhedra containing 76% (111)-twined hexagons (in 2D projection) were obtained; whereas, when employing RhCl{sub 3} as the Metal Precursor in the presence of alkylammonium bromide, such as tetramethylammonium bromide and trimethyl(tetradecyl)ammonium bromide, (100)-oriented Rh nanocubes were obtained with 85% selectivity. The {l_brace}100{r_brace} faces of the Rh nanocrystals are stabilized by chemically adsorbed Br{sup -} ions from alkylammonium bromides, which led to (100)-oriented nanocubes. Monolayer films of the (111)-oriented Rh nanopolyhedra and (100)-oriented Rh nanocubes were deposited on silicon wafers in a Langmuir-Blodgett trough to make model 2D nanoarray catalysts. These nanocatalysts were active for CO oxidation by O{sub 2}, and the turnover frequency was independent of nanoparticle shape, consistent with that previously observed for Rh(111) and Rh(100) single crystals
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Seedless Polyol Synthesis and CO Oxidation Activity of Monodisperse (111)- and (100)-Oriented Rhodium Nanocrystals in Sub-10 nm Sizes
langmuir, 2010Co-Authors: Zhang Yawen, Grass, Michael E., Huang Wenyu, Somorjai, Gabor A.Abstract:Monodisperse sub-10 nm (6.5 nm) sized Rh nanocrystals with (111) and (100) surface structures were synthesized by a seedless polyol reduction in ethylene glycol, with poly(vinylpyrrolidone) as a capping ligand. When using [Rh(Ac)(2)](2) as the Metal Precursor, (111)-oriented Rh nanopolyhedra containing 76% (111)-twinned hexagons (in 2D projection) were obtained; whereas, when employing RhCl(3) as the Metal Precursor in the presence of alkylammonium bromide, such as tetramethylammonium bromide and trimethyl(tetradecyl)ammonium bromide, (100)-oriented Rh nanocubes were obtained with 85% selectivity. The {100} faces of the Rh nanocrystals are stabilized by chemically adsorbed Br(-) ions from alkylammonium bromides, which led to (100)-oriented nanocubes. Monolayer films of the (111)-oriented Rh nanopolyhedra and (100)-oriented Rh nanocubes were deposited on silicon wafers in a Langmuir-Blodgett trough to make model 2D nanoarray catalysts. These nanocatalysts were active for CO oxidation by O(2), and the turnover frequency was independent of nanoparticle shape, consistent with that previously observed for Rh(111) and Rh(100) single crystals.Chemistry, MultidisciplinaryChemistry, PhysicalMaterials Science, MultidisciplinarySCI(E)EIPubMed17ARTICLE2116463-164682
Jérôme Lacour - One of the best experts on this subject based on the ideXlab platform.
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enantioselective cpru catalyzed carroll rearrangement ligand and Metal source importance
European Journal of Organic Chemistry, 2008Co-Authors: David Linder, Frédéric Buron, Samuel Constant, Jérôme LacourAbstract:The addition of unstabilized carbonyl nucleophiles to unsymmetrical allyl-Metal fragments still represents a challenge to generate stereogenic centers enantio- and regioselectively. In this context, the decarboxylative Carroll rearrangement of allyl -keto esters is particularly interesting, since chiral,-unsaturated ketones are obtained. Herein, we show that CpRu half-sandwich complexes can, with selected enantiopure pyridine-monooxazoline ligands, catalyze this transformation and afford complete conversions along with good levels of regioselectivity and enantioselectivity. Even more challenging (electron-poor) substrates react (up to 86 % ee, branched/linear ratio 97:03). In addition, the use of an air-stable Metal Precursor, namely [CpRu(6-naphthalene)][PF6], allows the reaction to be carried out reproducibly evenin non-anhydrous THF with a catalyst loading as low as2 mol-%.
Jeffrey W Elam - One of the best experts on this subject based on the ideXlab platform.
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a route to nanoscopic materials via sequential infiltration synthesis on block copolymer templates
ACS Nano, 2011Co-Authors: Qing Peng, Seth B. Darling, Yu-chih Tseng, Jeffrey W ElamAbstract:Sequential infiltration synthesis (SIS), combining stepwise molecular assembly reactions with self-assembled block copolymer (BCP) substrates, provides a new strategy to pattern nanoscopic materials in a controllable way. The selective reaction of a Metal Precursor with one of the pristine BCP domains is the key step in the SIS process. Here we present a straightforward strategy to selectively modify self-assembled polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) BCP thin films to enable the SIS of a variety of materials including SiO2, ZnO, and W. The selective and controlled interaction of trimethyl aluminum with carbonyl groups in the PMMA polymer domains generates Al-CH3/Al–OH sites inside the BCP scaffold which can seed the subsequent growth of a diverse range of materials without requiring complex block copolymer design and synthesis.
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supported ru pt biMetallic nanoparticle catalysts prepared by atomic layer deposition
Nano Letters, 2010Co-Authors: Steven T Christensen, Joseph L Libera, Peter C Stair, Jeffrey T Miller, Hao Feng, Jeffrey W ElamAbstract:Atomic layer deposition (ALD) is used to deposit ruthenium−platinum nanostructured catalysts using 2,4-(dimethylpentadienyl)(ethylcyclopentadienyl) ruthenium, trimethyl(methylcyclopentadienyl) platinum, and oxygen as Precursors. Transmission electron microscopy shows discrete 1.2 nm nanoparticles decorating the surface of the spherical alumina support. The Ru−Pt particles are crystalline and have a crystal structure similar to pure platinum. X-ray fluorescence measurements show that the nanoparticle composition is controlled by the ratio of Metal Precursor ALD cycles. X-ray absorption spectroscopy at the Ru K-edge indicates a nearest neighbor Ru−Pt interaction consistent with a biMetallic composition. Methanol decomposition reactions further confirm a Ru−Pt interaction and show enhanced methanol conversion for the biMetallic nanoparticles when compared to catalysts comprised of a mixture of pure Pt and Ru nanoparticles of similar loading. These results demonstrate that ALD is a viable technique for synthe...
Hongli Liu - One of the best experts on this subject based on the ideXlab platform.
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encapsulation of mono or biMetal nanoparticles inside Metal organic frameworks via in situ incorporation of Metal Precursors
Small, 2015Co-Authors: Liyu Chen, Xiaodong Chen, Hongli LiuAbstract:A facile, in situ Metal Precursor incorporation strategy is established for good control over the location and composition of Metal nanoparticles within Metal-organic frameworks (MOFs). This one-step Metal Precursor incorporation route is successfully applied to the fabrication of ultrafine Pd, Ni, and PdNi alloys to be selectively encapsulated inside the pores of MOFs, achieving superior catalytic activity and stability in the hydrogenation of nitrobenzene.