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Metallic hydrogen

Deborah Brazzolotto, Marcello Gennari, Nicolas Queyriaux, Trevor R Simmons, Jacques Pécaut, Serhiy Demeshko, Franc Meyer, Maylis Orio, Vincent Artero, Carole Duboc
Hydrogen production through water splitting is one of the most promising solutions for the storage of renewable energy. [NiFe] hydrogenases are organometallic enzymes containing nickel and iron centres that catalyse hydrogen evolution with performances that rival those of platinum. These enzymes provide inspiration for the design of new molecular catalysts that do not require precious metals. However, all heterodinuclear NiFe models reported so far do not reproduce the Ni-centred reactivity found at the active site of [NiFe] hydrogenases...
November 2016: Nature Chemistry
M Ibrahim, M A S Garcia, L L R Vono, M Guerrero, P Lecante, L M Rossi, K Philippot
The solution synthesis of rhodium nanoparticles (Rh NPs) was achieved from the organometallic complex [Rh(η(3)-C3H5)3] under mild reaction conditions in the presence of a polymer (PVP), a monophosphine (PPh3) and a diphosphine (dppb) as a stabilizer, leading to very small Rh NPs of 2.2, 1.3 and 1.7 nm mean size, with PVP, PPh3 and dppb, respectively. The surface properties of these nanoparticles were compared using a model catalysis reaction namely, hydrogenation of cyclohexene, first under colloidal conditions and then under supported conditions after their immobilization onto an amino functionalized silica-coated magnetite support...
October 21, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Libin Yang, Kunyang Wang, Gu Du, Wenxin Zhu, Liang Cui, Chengxiao Zhang, Xuping Sun, Abdullah M Asiri
Hydrogen has been considered as an ideal energy carrier for replacing fossil fuels to mitigate global energy crises. Hydrolysis of sodium borohydride (NaBH4) is simple and effective for hydrogen production but needs active and durable catalysts to accelerate the kinetics. In this paper, we demonstrate that cobalt phosphide nanowall arrays supported on carbon cloth (CoP NAs/CC) efficiently catalyze the hydrolytic dehydrogenation of NaBH4 with an activation energy of 42.1 kJ mol(-1) in alkaline media. These monolithic CoP NAs/CC show a maximum hydrogen generation rate of [Formula: see text] and are robust with superior durability and reusability...
October 21, 2016: Nanotechnology
Deven P Estes, Georges Siddiqi, Florian Allouche, Kirill V Kovtunov, Olga E Safonova, Alexander L Trigub, Igor V Koptyug, Christophe Copéret
The activation and conversion of hydrocarbons is one of the most important challenges in chemistry. Transition-metal ions (V, Cr, Fe, Co…) isolated on silica surfaces are known to catalyze these processes. The mechanisms of these processes are currently unknown but are thought to involve C-H activation as the rate determining step. Here, we synthesize well-defined Co(II) ions on a silica surface using a metal siloxide precursor followed by thermal treatment under vacuum at 500°C. We show that these isolated Co(II) sites are catalysts for a number of hydrocarbon conversion reactions, such as the dehydrogenation of propane, the hydrogenation of propene, and the trimerization of terminal alkynes...
October 21, 2016: Journal of the American Chemical Society
Benjamin S Gelfand, Racheal P S Huynh, Roger K Mah, George K H Shimizu
A crystalline and permanently porous copper phosphonate monoester framework has been synthesized from a tetraaryl trigonal phosphonate monoester linker. This material has a surface area over 1000 m(2)  g(-1) , as measured by N2 sorption, the highest reported for a phosphonate-based metal-organic framework (MOF). The monoesters result in hydrophobic pore surfaces that give a low heat of adsorption for CO2 and low calculated selectivity for CO2 over N2 and CH4 in binary mixtures. By careful manipulation of synthetic conditions, it is possible to selectively remove some of the monoesters lining the pore to form a hydrogen phosphonate while giving an isomorphous structure...
October 21, 2016: Angewandte Chemie
Zhuolei Zhang, Shenqiang Ren
Luminescent network: Colloidal excimer superstructures with unique optical and electronic properties have recently been described. Ground-state gold cluster cores were held together by the hydrogen-bonding network formed by their capping ligands, which enabled excimer formation.
October 20, 2016: Angewandte Chemie
Zhe Lv, Nasir Mahmood, Muhammad Tahir, Lun Pan, Xiangwen Zhang, Ji-Jun Zou
Transition metal dichalcogenides (TMDs) are emerging as promising materials, particularly for electrochemical and photochemical catalytic applications, and among them molybdenum sulfides have received tremendous attention due to their novel electronic and optoelectronic characteristics. Several review articles have summarized the recent progress on TMDs but no critical and systematic summary exists about the nanoscale fabrication of MoS2 with different dimensional morphologies. In this review article, first we will summarize the recent progress on the morphological tuning and structural evolution of MoS2 from zero-dimension (0D) to 3D...
October 20, 2016: Nanoscale
Jian-Cheng Wang, Yu-Hong Hu, Gong-Jun Chen, Yu-Bin Dong
Two copper-loaded MOF materials, namely Cu(ii)@Ui-O-66-NH2 (1) and Cu(0)@UiO-66-NH2 (2), are reported. They can, respectively, serve as highly efficient heterogeneous catalysts for olefin oxidation and hydrogenation under mild conditions. Complete styrene hydrogenation occurs in 15 min at ambient temperature with quantitative yield.
October 20, 2016: Chemical Communications: Chem Comm
Vahid Sokhanvaran, Saeid Yeganegi
The quantum mechanics (QM) method and Grand Canonical Monte Carlo (GCMC) simulations were performed to study the effect of lithium cation doping on the adsorption and separation of CO2, CH4 and H2 on 2-fold interwoven metal-organic framework (MOF) Zn2(NDC)2(diPyNI). The second order Moller-Plesset (MP2) calculations on the (Li+-diPyNI) cluster model showed that the energetically most favorable lithium binding site is above the pyridine ring side and at a distance of 1.817 Å from the oxygen atom. The results revealed that the adsorption capacity of Zn2(NDC)2(diPyNI) for carbon dioxide is higher than that of hydrogen and methane at room temperature...
October 19, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Ravdeep Kaur, Poonam Yadav, Ashwani Kumar Thukral, Amandeep Walia, Renu Bhardwaj
Plant growth regulator-assisted phytoremediation has been assessed as a novel strategy to improve phytoremediation potential of plants. In the present work, potential of castasterone, a plant growth regulator, combined with citric acid was explored for phytoremediation of cadmium in Brassica juncea seedlings. The seedlings were raised under controlled laboratory conditions for 7 days. Results revealed that 0.6 mM cadmium exposure induced toxicity in the seedlings, which was reflected through root growth inhibition, accumulation of hydrogen peroxide and malondialdehyde, and loss of cell viability...
October 17, 2016: Environmental Science and Pollution Research International
Maciej Ptak, Mirosław Mączka, Anna Gągor, Adam Sieradzki, Bartosz Bondzior, Przemysław Dereń, S Pawlus
We report the synthesis, crystal structure, dielectric, vibrational and emission spectra of heterometallic MOFs, [C2H5NH3][Na0.5Cr0.5(HCOO)3] (EtANaCr), [C2H5NH3][Na0.5Al0.5(HCOO)3] (EtANaAl) and [C2H5NH3][Na0.5Al0.475Cr0.025(HCOO)3] (EtANaAlCr). These compounds crystallize in non-centrosymmetric monoclinic polar structures (space group Pn) and undergo order-disorder phase transitions upon heating to the monoclinic centrosymmetric structure (space group P21/n) at 369 (EtANaAl) and 373 K (EtANaCr). In principle, they are ferroelectric below these temperatures...
October 18, 2016: Physical Chemistry Chemical Physics: PCCP
Marco Sturaro, Enrico Della Gaspera, Niccolò Michieli, Carlo Cantalini, Seyed Mahmoud Emamjomeh, Massimo Guglielmi, Alessandro Martucci
Highly doped wide band gap metal oxides nanocrystals have recently been proposed as building blocks for applications as transparent electrodes, electrochromics, plasmonics, and optoelectronics in general. Here we demonstrate the application of gallium doped zinc oxide (GZO) nanocrystals as novel plasmonic and chemiresistive sensors for the detection of hazardous gases including hydrogen (H2) and nitrogen dioxide (NO2). GZO nanocrystals with a tunable surface plasmon resonance in the near infrared are obtained using a colloidal heat-up synthesis...
October 18, 2016: ACS Applied Materials & Interfaces
Yassine Oumellal, Karine Provost, Camelia Matei Ghimbeu, Alicia Martinez de Yuso, Claudia Zlotea
In-depth clarification of hydrogen interaction with noble metal nanoparticles and nanoalloys is essential for further development and design of efficient catalysts and hydrogen storage nanomaterials. This issue becomes even more challenging for nanoalloys of bulk-immiscible metals. The hydrogen interaction with bulk-immiscible Pd-Rh nanoalloys (3-6 nm) supported on mesoporous carbon is studied by both laboratory and large scale facility techniques. X-ray diffraction (XRD) reveals a single phase fcc structure for all nanoparticles confirming the formation of nanoalloys in the whole composition range...
October 17, 2016: Nanotechnology
Nongnuch Artrith, Wutthigrai Sailuam, Sukit Limpijumnong, Alexie M Kolpak
Water electrolysis is a key technology for the replacement of fossil fuels by environmentally friendly alternatives, but state-of-the-art water oxidation catalysts rely on rare elements such as Pt groups and other noble metals. In this article, we employ first-principles calculations to explore the potential of modified barium titanate (BaTiO3), an inexpensive perovskite oxide that can be synthesized from earth-abundant precursors, for the design of efficient water oxidation electrocatalysts. Our calculations identify Fe and Ni doping as a means to improve the electrical conductivity and to reduce the overpotential required for water oxidation over BaTiO3...
October 17, 2016: Physical Chemistry Chemical Physics: PCCP
Monserrat Alfonso, Helen Stoeckli-Evans
The title isotypic complexes, bis-[μ-5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carboxylato]-κ(4)N(1),O(2),N(6):O(3);κ(4)O(3):N(1),O(2),N(6)-bis-[di-aqua-manganese(II)] tetra-hydrate, [Mn2(C16H8N4O4)2(H2O)4]·4H2O, (I), and bis-[μ-5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carboxyl-ato]-κ(4)N(1),O(2),N(6):O(3);κ(4)O(3):N(1),O(2),N(6)-bis-[di-aqua-iron(II)] tetrahydrate, [Fe2(C16H8N4O4)2(H2O)4]·4H2O, (II), are, respectively, the mangan-ese(II) and iron(II) complexes of the ligand 5,6-bis-(pyridin-2-yl)-pyrazine-2,3-di-carb-oxy-lic acid...
October 1, 2016: Acta Crystallographica. Section E, Crystallographic Communications
Jong Won Shin, Dong Won Lee, Dae-Woong Kim, Dohyun Moon
The title compound, [CuCl2(C10H16N2O)], has been synthesized and characterized by synchrotron single-crystal X-ray diffraction and FT-IR spectroscopy. The 2-methyl-2-[(pyridin-2-ylmeth-yl)amino]-propan-1-ol (mpmapOH) ligand, including pyridine, amine and hy-droxy groups, was synthesized by the reaction of 2-amino-2-methyl-propan-1-ol with pyridine-2-carbaldehyde and was characterized by NMR spectroscopy. In its Cu(II) complex, the metal ion has a distorted square-pyramidal coordination geometry with two N and one O atom of the mpmapOH ligand and one chloride anion in the equatorial plane, and the second chloride in an axial position...
October 1, 2016: Acta Crystallographica. Section E, Crystallographic Communications
Petra Martini, Alessandra Boschi, Gianfranco Cicoria, Licia Uccelli, Micòl Pasquali, Adriano Duatti, Gaia Pupillo, Mario Marengo, Massimo Loriggiola, Juan Esposito
The design and fabrication of a fully-automated, remotely controlled module for the extraction and purification of technetium-99m (Tc-99m), produced by proton bombardment of enriched Mo-100 molybdenum metallic targets in a low-energy medical cyclotron, is here described. After dissolution of the irradiated solid target in hydrogen peroxide, Tc-99m was obtained under the chemical form of (99m)TcO4(-), in high radionuclidic and radiochemical purity, by solvent extraction with methyl ethyl ketone (MEK). The extraction process was accomplished inside a glass column-shaped vial especially designed to allow for an easy automation of the whole procedure...
October 5, 2016: Applied Radiation and Isotopes
Paolo Pirovano, Erik R Farquhar, Marcel Swart, Aidan Richard McDonald
Two metastable NiIII complexes, [NiIII(OAc)(L)] and [NiIII(ONO2)(L)] (L = N,N'-(2,6-dimethylphenyl)-2,6-pyridinedicarboxamidate, OAc = acetate), were prepared, adding to the previously prepared [NiIII(OCO2H)(L)], with the purpose of probing the properties of terminal late-transition metal oxidants. These high-valent oxidants were prepared by the one-electron oxidation of their NiII precursors ([NiII(OAc)(L)]- and [NiII(ONO2)(L)]-) with tris(4-bromophenyl)ammoniumyl hexachloroantimonate. Fascinatingly, the reaction between any [NiII(X)(L)]- and NaOCl/acetic acid (AcOH) or cerium ammonium nitrate ((NH4)2[CeIV(NO3)6], CAN), yielded [NiIII(OAc)(L)] and [NiIII(ONO2)(L)], respectively...
October 14, 2016: Journal of the American Chemical Society
Wolfgang W Schoeller, Guido D Frey
The oxidative addition of π- and σ-bonds is studied by means of quantum chemical investigations at a MCSCF and density functional level of sophistication. The title compound (AlNacNac) induces first-order strong donor-acceptor abilities in the triplet state, giving rise to biradicaloid adducts. At second-order, it reveals carbene character. The energy barriers for the 1,2-addition reactions are fairly small, resulting from an oxidative addition, which differs from the classical 1,2-addition reaction of a carbene to an olefin...
October 14, 2016: Inorganic Chemistry
Giacomo M Lari, Olivier G Gröninger, Qiang Li, Cecilia Mondelli, Núria López, Javier Pérez-Ramírez
Sugar alcohols are applied in the food, pharmaceutical, polymer, and fuel industries and are commonly obtained by reduction of the corresponding saccharides. In view of the rarity of some sugar substrates, epimerization of a readily available monosaccharide has been proposed as a solution, but an efficient catalytic system has not yet been identified. Herein, a molybdenum heteropolyacid-based catalyst is developed to transform glucose, arabinose, and xylose into less-abundant mannose, ribose, and lyxose, respectively...
October 14, 2016: ChemSusChem
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