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Metallic hydrogen

Peng Zhou, Zehui Zhang
A new method was developed for the synthesis of secondary amines by the one-pot reductive amination of carbonyl compounds with nitro compounds with formic acid as the hydrogen donor over a heterogeneous non-noble metal catalyst (Co-Nx/C-800-AT). Both nitrogen and cobalt were of great importance in the transfer hydrogenation reactions with formic acid.
March 27, 2017: ChemSusChem
Tatsuya Shinagawa, Marcus Tze-Kiat Ng, Kazuhiro Takanabe
The development of cost-effective and active water-splitting electrocatalysts that work at mild pH is an essential step towards the realization of sustainable energy and material circulation in our society. Its success requires a drastic improvement in the kinetics of the anodic half-reaction of the oxygen evolution reaction (OER), which determines the overall system efficiency to a large extent. A simple electrochemical protocol has been developed to activate Ni electrodes, by which a stable NiOOH phase was formed, which could weakly bind to alkali-metal cations...
March 27, 2017: Angewandte Chemie
Ana Djuric, Aida Begic, Borko Gobeljic, Ana Pantelic, Goran Zebic, Ivana Stevanovic, Dragan Djurdjevic, Milica Ninkovic, Vera Prokic, Ivan Stanojevic, Danilo Vojvodic, Mirjana Djukic
The aim of the study was to investigate if alcohol and disulfiram (DSF) individually and in combination affect bioelements' and red-ox homeostasis in testes of the exposed rats. The animals were divided into groups according to the duration of treatment (21 and/or 42 days): C21/C42 groups (controls); OL21/OL42 groups (0.5 mL olive oil intake); A1-21 groups (3 mL 20% ethanol intake); DSF1-21 groups (178.5 mg DSF/kg/day); and A21+DSF22-42 groups (the DSF ingestion followed previous 21 days' treatment with alcohol)...
March 23, 2017: Food and Chemical Toxicology
Haohong Duan, Dongguo Li, Yan Tang, Yang He, Ji Shu Fang, Rongyue Wang, Haifeng Lv, Pietro P Lopes, Arvydas P Paulikas, Haoyi Li, Scott X Mao, Chong-Min Wang, Nenad M Markovic, Jun Li, Vojislav R Stamenkovic, Yadong Li
Search for active, stable and cost-efficient electrocataltysts for hydrogen production via water splitting could make substantial impact to the energy technologies that do not rely on fossil fuels. Here we report the synthesis of rhodium phosphide electrocatalyst with low metal loading in the form of nanocubes (NCs) dispersed in high surface area carbon (Rh2P/C) by a facile solvo-thermal approach. The Rh2P/C exhibit remarkable performance for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) compared to Rh/C and Pt/C catalysts...
March 26, 2017: Journal of the American Chemical Society
Maxim S Panov, Olga A Vereshchagina, Sergey S Ermakov, Ilya I Tumkin, Evgeniia M Khairullina, Mikhail Yu Skripkin, Andrey S Mereshchenko, Mikhail N Ryazantsev, Vladimir A Kochemirovsky
The synthesis of conductive gold and copper-gold microstructures with high developed surface based on the method of laser-induced metal deposition from solution was developed. The topology and crystallization phase of these structures were observed by means of scanning electron microscopy and X-ray diffraction, respectively. The electrochemical properties of the synthesized materials were investigated using cyclic voltamperometry and amperometry. According to the obtained results, it was found out that copper-gold microstructures demonstrate a linear dependence of Faraday current vs...
May 15, 2017: Talanta
Noor Zaouri, Leonardo Gutierrez, Laure Dramas, Daniel Garces, Jean-Philippe Croue
In the current study, the interfacial interactions between the high molecular weight (HMW) compounds of Skeletonema costatum (SKC) extracellular organic matter (EOM) and ZrO2 or Al2O3, were investigated by atomic force microscopy (AFM). HMW SKC-EOM was rigorously characterized and described as a hydrophilic organic compound mainly comprised of polysaccharide-like structures. Lipids and proteins were also observed, although in lower abundance. HMW SKC-EOM displayed attractive forces during approaching (i.e., leading to jump-to-contact events) and adhesion forces during retracting regime to both metal oxides at all solution conditions tested, where electrostatics and hydrogen bonding were suggested as dominant interacting mechanisms...
March 21, 2017: Water Research
Viruthasalam Maruthapandian, Mahendran Mathankumar, Velu Saraswathy, Balasubramanian Subramanian, Srinivasan Muralidharan
Catalysts for the oxygen evolution reaction (OER) play an important role in the conversion of solar energy to fuel of earth abundant water into H2 and O2 through splitting/electrolyzer. The heterogeneous electrocatalysts for hydrogen and oxygen evolution reactions (HER and OER) exhibit catalytic activity that depends on the electronic properties, oxidation states and local surface structure. Spinel ferrites (MFe2O4; M = Ni and Co) based materials have been attractive for the catalytic water oxidation due to their well-known stability in alkaline medium, easy synthesis, existence of metal cations with various oxidation states, low cost and tunable properties by the desired metal substitution...
March 24, 2017: ACS Applied Materials & Interfaces
Minghao Zhuang, Yao Ding, Xuewu Ou, Zhengtang Luo
The edge and corner atoms of 2D transition metal dichalcogenides (TMDCs) are the main electrocatalytically active sites for electrochemical reaction. Here, we demonstrate an approach to generate abundant edge/corner atoms in molybdenum diselenide (MoSe2) nanocrystals supported by nitrogen-doped graphene (NG) which consequently leads to significantly enhanced hydrogen evolution reaction (HER) activity. These structures were fabricated by firstly absorbing the Mo-containing precursor within polymer-functionalized graphene oxide, then selenized to obtain MoSe2 nanocrystals on the surface, and finally H2 etching was performed to form perforated structures...
March 24, 2017: Nanoscale
Quan Shuai, Sven Kaufmann, Daniel J Auerbach, Dirk Schwarzer, Alec M Wodtke
The dissociative adsorption reaction of hydrogen on noble metals is believed to be well-described within the Born-Oppenheimer approximation. In this work, we have experimentally derived translational energy distributions for selected quantum states of H2 and D2 formed in associative desorption reactions at a Au(111) surface. Using the principle of detailed balance, we compare our results to theory carried out at the same level of sophistication as was done for the reaction on copper. The theory predicts translational excitation that is much higher than is seen in experiment and fails to reproduce the experimentally observed isotope effect...
March 27, 2017: Journal of Physical Chemistry Letters
Patrick Steiger, Renaud Delmelle, Debora Foppiano, Lorenz Holzer, Andre Heel, Maarten Nachtegaal, Oliver Kröcher, Davide Ferri
Perovskite-type oxides have shown the ability to reversibly segregate precious metals from their structure. This reversible segregation behavior was explored for a commonly used catalyst metal, Ni, to prevent Ni sintering, which is observed on most catalyst support materials. TPR, XRD, XAS, electron microscopy and catalytic activity tests were used to follow the extent of reversible Ni segregation. LaFe1 xNixO3±δ (0 ≤ x ≤ 0.2) was synthesized using a citrate based solution process. After reduction at 600°C metallic Ni particles were displayed on the perovskite surfaces, which showed to be active towards the hydrogenation of CO2...
March 24, 2017: ChemSusChem
V S Anithaa, R Shankar, S Vijayakumar
The functionalization of graphene with transition metals is of great interest due to its wide range of applications, such as hydrogen storage, spintronics, information storage, etc. Due to its magnetic property adsorption of Mn atom on graphene has a high consequence on the electronic properties of graphene. The increase in size of the graphene sheet with hydrogen termination has a high impact on the transformation of electronic properties of the graphene sheet. Hence in this work, we investigate the size as well as change in structural and electronic properties of pristine/defective graphene sheets on adsorption of Mn atom using density functional theory methods...
April 2017: Journal of Molecular Modeling
Hasan Pašalić, Adelia J A Aquino, Daniel Tunega, Georg Haberhauer, Martin H Gerzabek, Hans Lischka
Cation-π interactions were systematically investigated for the adsorption of H(+) and alkali metal cations M(+) to pyrene by means of Møller-Plesset perturbation theory (MP2) and density functional theory (DFT). The main aims were to determine the preferred adsorption sites and how the microhydration shell influences the adsorption process. The preferred adsorption sites were characterized in terms of structural parameters and energetic stability. Stability analysis of the M(+)-pyrene complexes revealed that the binding strength and the barrier to transitions between neighboring sites generally decreased with increasing cation size from Li(+) to Cs(+)...
April 2017: Journal of Molecular Modeling
Ying Chen, Hongqi Sun, Wenchao Peng
Photocatalysis have attracted great attention due to their useful applications for sustainable hydrogen evolution and pollutants degradation. Transition metal dichalcogenides (TMDs) such as MoS₂ and WS₂ have exhibited great potential as cocatalysts to increase the photo-activity of some semiconductors. By combination with graphene (GR), enhanced cocatalysts of TMD/GR hybrids could be synthesized. GR here can act as a conductive electron channel for the transport of the photogenerated electrons, while the TMDs nanosheets in the hybrids can collect electrons and act as active sites for photocatalytic reactions...
March 15, 2017: Nanomaterials
Marcel Neeleman, Nissim Kanekar, J Xavier Prochaska, Marc Rafelski, Chris L Carilli, Arthur M Wolfe
Gas surrounding high-redshift galaxies has been studied through observations of absorption line systems toward background quasars for decades. However, it has proven difficult to identify and characterize the galaxies associated with these absorbers due to the intrinsic faintness of the galaxies compared with the quasars at optical wavelengths. Using the Atacama Large Millimeter/Submillimeter Array, we report on detections of [C ii] 158-μm line and dust-continuum emission from two galaxies associated with two such absorbers at a redshift of z ~ 4...
March 24, 2017: Science
Hoik Lee, Duy-Nam Phan, Myungwoong Kim, Daewon Sohn, Seong-Geun Oh, Seong Hun Kim, Ick Soo Kim
Palladium (Pd) metal is well-known for hydrogen sensing material due to its high sensitivity and selectivity toward hydrogen, and is able to detect hydrogen at near room temperature. In this work, palladium-doped carbon nanofibers (Pd/CNFs) were successfully produced in a facile manner via electrospinning. Well-organized and uniformly distributed Pd was observed in microscopic images of the resultant nanofibers. Hydrogen causes an increment in the volume of Pd due to the ability of hydrogen atoms to occupy the octahedral interstitial positions within its face centered cubic lattice structure, resulting in the resistance transition of Pd/CNFs...
November 29, 2016: Nanomaterials
David Thompson, David Kranbuehl, Eliane Espuche
This paper presents a continuous single-step route that permits preparation of a thermostable polymer/metal nanocomposite film and to combine different functional properties in a unique material. More precisely, palladium nanoparticles are in situ generated in a polyimide matrix thanks to a designed curing cycle which is applied to a polyamic acid/metal precursor solution cast on a glass plate. A metal-rich surface layer which is strongly bonded to the bulk film is formed in addition to homogeneously dispersed metal nanoparticles...
October 18, 2016: Nanomaterials
Hak Ki Yu
We have developed self-assembled copper (Cu) micro-labyrinth (ML) with graphene skin for transparent flexible electrodes of optoelectronic devices. The Cu ML is simply formed by heating a thin Cu film with a 100-nm thickness on a SiO₂/Si substrate at 950 °C under hydrogen ambient to block the oxidation. Moreover, the Cu ML can have graphene skin at the surface by inserting carbo-hydroxyl molecules (CxHy) during heating due to the catalytic decomposition of C-H bonds on the Cu surface. The Cu ML with graphene skin (Cu ML-G) has superior sheet resistivity below 5 Ω/sq and mechanical flexibility without cracks at the bending radius of 0...
September 1, 2016: Nanomaterials
Soundarrajan Chandrasekaran, Thomas Nann, Nicolas H Voelcker
The performance of silicon for water oxidation and hydrogen production can be improved by exploiting the antireflective properties of nanostructured silicon substrates. In this work, silicon nanowires were fabricated by metal-assisted electroless etching of silicon. An enhanced photocurrent density of -17 mA/cm² was observed for the silicon nanowires coated with an iron sulphur carbonyl catalyst when compared to bare silicon nanowires (-5 mA/cm²). A substantial amount of 315 µmol/h hydrogen gas was produced at low bias potentials for the silicon nanowires coated with an iron sulphur carbonyl catalyst...
August 5, 2016: Nanomaterials
Ju Ying Li, Qing Song Mei
TiAl₃ and TiN composite nanoparticles were continuously synthesized from Ti-48Al master alloy by hydrogen plasma-metal reaction in a N₂, H₂ and Ar atmosphere. The phase, morphology, and size of the nanoparticles were studied by X-ray diffraction (XRD) and transmission electronic microscopy (TEM). X-ray photoelectron spectroscopy (XPS) and evolved gas analysis (EGA) were used to analyze the surface phase constitution and oxygen content of the nanoparticles. The as-synthesized nanopowders were mainly composed of nearly spherical TiAl₃ and tetragonal TiN phases, with a mean diameter of ~42 nm and mass fractions of 49...
June 1, 2016: Nanomaterials
Xun Cui, Peng Xiao, Jing Wang, Ming Zhou, Wenlong Guo, Yang Yang, Yanjie He, Zewei Wang, Yingkui Yang, Yunhuai Zhang, Zhiqun Lin
Three-dimensional (3D) interconnected metal alloy nanostructures possess superior catalytic performance owing to their advantageous characteristics, including improved catalytic activity, corrosion resistance, and stability. Hierarchically structured Ni-Cu alloys composed of 3D network-like microscopic branches with nanoscopic dendritic feelers on each branch were crafted by a facile and efficient hydrogen evolution-assisted electrodeposition approach. They were subsequently exploited for methanol electrooxidation in alkaline media...
March 23, 2017: Angewandte Chemie
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